PLANT CANADA 2003

Forests of Land and Sea Forets de Terre et Mer

Joint Annual Meetings/Les Congres Annuels

Canadian Botanical Association/ Association Botanique du Canada Canadian Society of Plant Physiologists/Societe Canadienne de Ia

Physiologie V egetale

With the

11th New Phytologist Symposium

Plant Speciation

St. Francis Xavier University, Antigonish, NS June 25-29, 2003

ABSTRACT BOOK

ABSTRACTS OF PAPERS PRESENTED AT PLANT CANADA 2003 AND THE 11TH NEW PHYTOLOGIST

SYMPOSIUM, PLANT SPECIATION

St. Francis Xavier University Antigonish, Nova Scotia

June 25-29, 2003

Edited by:

David J. Garbary

&

Moira E. Galway

Department of Biology, St. Francis Xavier University

Copyright 2003 by Plant Canada

l

Table of Contents -Abstracts

Symposium Forests of Land and Sea ..................................................... I

Symposium Invasive plants: The Problems and Potential Solutions ........... 3

Symposium Light, Signal Transduction and Gene Expression ................... 6

Plenary lectures Tales of fish and forests: Paleolimnology and nutrient dynamics John Smol ..................................................................... 9 Videomicroscopy of living diatoms Jeremy Pickett-Heaps ................................................................ 9

Weresub Lecture Micro-fungi and large buildings: What have air quality investigations taught us about micro-fungi? A mycologist's perspective Thomas Rand .............................................................. 10

Plant Canada Contributed oral presentations ......................................... 11 Contributed poster presentations ...................................... 39

Plant Speciation Symposium Contributed oral presentations ......................................... 62 Contributed poster presentations ....................................... 74

Index of authors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..................... 94

11

All Conference Symposium

Forests of Land and Sea

1 Hydraulic architecture and tree performance TYREE, M.T. U.S. Forest Service, 705 Spear St. PO Box 968, Burlington, VT 05402 USA I will review literature on the hydraulic architecture of trees and tree performance. There is increasing evidence that tree performances measured in terms of gas exchange, net carbon gain and growth rate are controlled by the hydraulic sufficiency of roots and stems to conduct water to leaves, i.e. what is called the hydraulic architecture of trees. I will also give examples how stresses (such as drought and frost) can cause xylem dysfunction and reduce the hydraulic properties of wood.

2 Cascading ecological and evolutionary effects of seaweed chemical defenses HAY, MARK E. School of Biology, Georgia Institute of Technology, Atlanta, GA 30332-0230, USA Seaweeds evolve chemical defenses to deter larger consumers like fishes and urchins. However, these defended seaweeds then become sites of evolutionary opportunity for small, sedentary herbivores that can escape or deter their own consumers by associating with chemically noxious algae. These smaller consumers evolve tolerance to seaweed defenses and commonly use the compounds that deter fishes to recognize their preferred hosts. Thus, "feeding" specialization is really "habitat" specialization, and is driven by the need for small sedentary herbivores to escape predation rather than by nutritional traits of the host. Chemical defenses also show strong geographic patterns (more in tropical than in temperate species), local patterns (more in herbivore-rich than in herbivore-poor sites), and within thallus patterns (concentrated in parts of the plant, or at times of the season or even day when herbivores are more active). Some intraspecific variance in defenses is caused by variance in physical stress or induction of defenses following attack by small herbivores. In some cases, geographic variance in herbivore feeding choices, behavior, and evolution is driven by the indirect effects of seaweed defenses. Thus, chemical defenses often produce cascading effects that impact the ecology and evolution of marine systems as a whole.

3 How are algal extracellular matrices related to cell walls of degenerate land algae (land plants) GRETZ, MICHAEL R. Dept. Biological Sciences, Michigan Technological University, Houghton, Ml 49931 The algae do things a little differently as far as their extracellular polymers are concerned. Some algae produce cellulose microfibrils in much the same way as higher plants, from hexagonal rosette structures (terminal complexes) in the plasma membrane, whereas others utilize linear terminal complexes to create microfibrils of exceptional size, shape and crystallinity. Some algae cannot even confine synthesis of the world's

ABSTRACTS

most abundant biological macromolecule to the cell surface, but have the audacity to create cellulosic scales in Golgi cisternae. Cyanobacterial cellulose synthases are closely related to those of higher plants, which implys an ancient origin of eukaryotic CesAs. Algae can't be content with the variety of hemicellulosic polymers in higher plants, they produce a diverse collection including xyloglucans, xylans, mannans, glucomannans and others. Several green algae have polymers with pectin epitopes and the prasinophycean algae produce pectinlike carbohydrate containing unusual 2-keto-sugar acids found also in higher plants, but the red algae produce a startling variety of sulphated galactans that serve as their major ionic polymers. Whereas the fungi are perfectly content to place their alpha-chitin into vesicles and then into the cell wall, certain diatoms produce long, highly crystalline beta-chitin fibrils at the plasma membrane that project through the silica frustule. The biomineralization process that leads to the intricately detailed silica "house" that surrounds the protoplasm is being dissected today with the delineation of a novel group of diatom proteins, frustulins and silaffins. Discovery of the nature of the polymers involved in diatom and cyanobacterial motility has recently highlighted the fact that algae use their extracellular polymers not only for the mundane functions assigned to higher plant cell walls such as regulating cell volume and determining cell shape.

4 Will work for food: fungal symbionts of plants and seaweeds DECKERT, R.J. Department of Biological Sciences, Northern Arizona University, Flagstaff AZ, 86004 Photosynthetic autotrophs and fungi share a long history of association that began in the sea and continued with the colonization of terrestrial environments. Importantly, fungal symbionts are often key mutualists that have facilitated the movement of plants into new niches and stressful environments. Today, root mutualistic fungal symbioses, the mycorrhizas, are recognized as virtually obligate partnerships between plants and fungi in most terrestrial ecosystems. Other fungi that asymptomatically inhabit the aerial tissues of plants, or endophytes, are potentially important symbionts that, in some cases, form obligate conjunctive associations with their host to produce composite organisms. The impetus behind the development of plant -fungal mutual isms are the challenges presented by biotic and abiotic factors in the environment in which the exhabitant lives. Because the nature of the challenges faced in marine and terrestrial habitats is fundamentally different, this is reflected in the different nature of the mutualistic associations that arise between autotrophs and fungi in the two biomes. Indications are that these mutual isms can be of tremendous importance to ecosystem function as well as a large source of cryptic biodiversity in both marine and terrestrial environments.

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5

CBA/ABC Symposium

Invasive Plants: The Problem and Potential Solutions

Symposium Co-ordinator- Pamela Krannitz Environment Canada, Canadian Wildlife Service, Delta, BC

Patterns of plant invasions: The rich get richer STOHLGREN, T.J. 1

, BARNETT, D.T. 1, KARTESZ, J.T.2 & #KRANNITZ P.G.3

1National Institute of Invasive Species Science, USGS, Fort Collins, CO; 2Biota ofNorth America Program, University of North Carolina, NC; 3 Environment Canada, Canadian Wildlife Service, Delta, BC. Observations from islands, small-scale experiments, and mathematical models have generally supported a long held paradigm in ecology that habitats of low plant diversity in natural areas are more vulnerable to plant invasions than areas of high plant diversity. The theory held that competitive exclusion, through the pre-emption of natural resources by native species, immunizes species-rich areas from invasion by plant species from other countries. We summarize two large, independent datasets to show exactly the opposite pattern at multiple spatial scales, but more significant (and alarming) at larger spatial scales: hotspots of native plant diversity have been far more heavily invaded than areas of low plant diversity in most parts of the United States. Our findings suggest that we cannot expect hotspots of native plant species richness to repel invasions and that the threats of species invasion are significant and predictably greatest in species-rich areas. The same pattern has been observed in a study comparing species richness of l 0 sites in British Columbia.

6 Invasive plants in urban environments: City of Toronto control programs WEBSTER, C.L. City of Toronto, Urban Forestry Services, Toronto, ON Invasive plants are being recognized globally as a significant threat to natural areas. In urban environments, invasive plant effects are intensified by ongoing land development, increasing human populations and pollution. The City of Toronto, Urban Forestry Services has acknowledged the need for active management by implementing invasive plant control programs in selected parks and ravines. Management priorities are determined by environmental and economic factors, such as invasive species ranking, extent of population establishment, quality of surrounding plant communities and staff requirements. A combination of prescribed burns, manual removals and herbicide applications are being used in city parks to control the spread of invasive plants. Public education regarding these methods has been challenging due to the high visibility and accessibility of these urban parks. High Park has been set up as a test pilot project to assess the possibility of controlling invasive plants to allow native plant regeneration on a landscape scale. The isolation of High Park from other natural areas and the presence of rare Black Oak savannah habitat within the park make it an ideal test location. Across Canada, other municipalities have started similar programs, however, public education and further resources will be needed to expand and link these programs.

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7 Invasive plants of Canadian woodlands- scientific challenges BAZEL Y, DAWN R., J. FIRANSKI, CARRIE & KOH, SAEW AN Department of Biology, York University, 4700, Keele Street, Toronto, Ontario MJJ 1 PJ. About 28% of the Canadian flora are non-indigenous species (NIS). What is their impact on woodlands? There are some spectacular introduced invasive plants in North America, such as Tamarix, which is a keystone species capable of altering ecosystem structure and function. However, most NIS simply add to the species richness of an area. How should we measure their ecological impact? Is it realistic to try to eradicate introduced species? Such questions are best evaluated in the context of a multi-scale ecological approach that allows for adaptive management. Using examples of both management programmes and our own research from parks in the deciduous forest region of Ontario we will illustrate the effectiveness of this approach. We have found that one so-called invasive plant species, garlic mustard, Alliaria petiolata, was not having a major impact on forest plant communities in two sites, and that ecosystem and landscape-level disturbances were of much greater significance in determining plant community composition. Nevertheless, it is vital to remember that eradication of any invasive plant species has never been achieved, except at regional and local scales, at great cost, and that this is for a very few plant species. Thus, the main take home message about NIS is a cautious one - "when in doubt, keep them out!"

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Facilitative interactions between alien species mediate an ecosystem phase shift from Laminaria forests to Codium meadows on the Atlantic coast of Nova Scotia SCHEIBLING, R.E. Department of Biology, Dalhousie University, Halifax, NS, BJH 4Jl. As accidental introductions of alien species to coastal ecosystems accelerate on a global scale, there is growing concern about potential threats to biodiversity and the integrity of native marine communities. Along the Atlantic coast ofNova Scotia, major changes in the structure of the rocky subtidal community have occurred during the past two decades. These "ecosystem phase shifts" are associated with sequential introductions of three non-native species: 1) a pathogenic amoeba (Parameoba invadens) that kills sea urchins (the dominant herbivores), enabling kelps and other seaweeds to thrive; 2) an epiphytic bryozoan (Membranipora membranacea) that encrusts kelps, causing severe defoliation of kelp forests; and 3) a green alga (Codiumfragi/e spp. tomentosoides) that exploits windows of opportunity created by the former species to become established and spread rapaciously. These aliens appear to have acted synergistically to facilitate transitions between alternative phases of this ecosystem: from sea urchin barrens to kelp forests and, most recently, to what is perhaps the most insidious and persistent phase, Codium meadows. I will examine interactions between native and introduced species that mediate the phase shifts and discuss implications of these changes for the structure and functioning of the ecosystem, and the resources we extract from it.

9 Towards preventing the introduction of more invasive horticultural species NICHOLLS, WILF Botanical Garden, Memorial University of Newfoundland, St. John's, NL, A I C 5S7 New products are crucial to most industries. Be it cars, soap or paper towels, the promotion of new or improved products or ingredients is ubiquitous. The horticultural industry is no different; new introductions are in demand and ornamental R&D programs abound at seed companies, nurseries, government facilities, botanical gardens and the backyards of hobbyists. Plant exploration, whence came so many garden favourites, continues to deliver exciting novelties albeit at a more selective and restrained pace than in the halcyon days of Farrer, Banks, the Hookers and Douglas. Few will argue that some serious invasive plants are the result of horticultural introductions

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but oft-time fervent blame laid at the feet of gardeners and industry may obscure factors, decisions and actions of other parties, some dating back a century. It is, today, a shared responsibility demanding a shared response. As countries develop lists and policies, it behoves us to be proactive, co-operative and communicative; the nursery industry can and should do its part to address the situation or risk more external impositions of restrictions. Botanical Gardens can and should develop collection policies, local awareness and educational programs. Cities, restoration and highway planners must be part of the solution. Action and decision-making must be based on skilled observation, evaluation and cooperation between regulatory bodies and user-groups through common sense and practicable guidelines.

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10

CSPP/SCPV Symposium

Light, Signal Transduction and Gene Expression

Symposium Co-ordinator - Robert Ireland Department of Biology, Mount Allison University, Sackville, NB

Control of chloroplast redox by the IMMUT ANS terminal oxidase RODERMEL, S.R. Department of Genetics, Development and Cell Biology, Iowa State University, Ames, /A 50014 The immutans (im) variegation mutant of Arabidopsis has green and white leaf sectors due to the lack of the IMMUT ANS (IM) protein. Sectoring is dependent on light intensity-the higher the light, the more white sectors that form. Plastids in the white im sectors lack an organized lamellar system and accumulate phytoene, a non­colored carotenoid biosynthetic intermediate. Cloning has revealed that IM is a novel plastid homolog of the mitochondrial alternative oxidase. IM has quinol oxidase activity in vitro, and because desaturation of phytoene by phytoene desaturase requires plastoquinone and molecular oxygen, our working hypothesis is that IM is a terminal oxidase in plastid membranes, where it acts to transfer electrons from the plastoquinol pool to molecular oxygen. Although IM plays a role in carotenogenesis, its function does not appear to be limited to this process, inasmuch as IM is expressed in all plant organs, even in those that do not accumulate carotenoids. Consistent with the idea that IM plays a general role in plastid metabolism, recent studies have shown that IM might be the elusive terminal oxidase of chlororespiration. IM might also act as a more general electron sink, providing a safety valve for photosynthesis under conditions of environmental stress. Leaf development is markedly altered in im, reflecting a defect in mechanisms that signal the nucleus about the developmental state of the plastid (plastid-to-nucleus signal transduction). In addition, the green sectors ofim have enhanced rates of photosynthesis, perhaps to compensate for a lack of photosynthesis in the white sectors. The green sectors also attempt to avoid photodamage by mechanisms that are characteristic of plants exposed to high light intensities. It is concluded that immutans is a model for studying source-sink interactions.

11 Chloroplast to nucleus communication triggered by Mg-protoporphyriniX accumulation STRAND, ASA1

'3

, ASAMI, TADA02 & CHORY, JOANNE1

1 Plant Biology Laboratory and Howard Hughes Medical Institute, The Salk Institute, La Jolla, CA, USA; 1Plant Functions Lab, RIKEN, Wako, Japan, 3Umea Plant Science Centre, Department of Forest Genetics and Plant Physiology (SLU), Umea, Sweden Plant cells co-ordinately regulate the expression of nuclear and plastid genes that encode components of the photosynthetic apparatus. Nuclear genes that regulate chloroplast development and chloroplast gene expression provide part of this co-ordinate control. There is also compelling evidence that information flows in the opposite direction, from chloroplasts to the nucleus. To date, at least three different signalling pathways have been identified that originate in the plastid and control nuclear gene expression; however, the molecular nature of these signals has remained unknown. Here we demonstrate that the tetrapyrrole intermediate Mg-protoporphyrin (Mg-ProtoiX) acts as a signalling molecule in one of the signalling pathways between the chloroplast and nucleus. Accumulation of Mg-ProtolX is both necessary and sufficient to regulate the expression of a large number of nuclear genes encoding chloroplastic proteins associated with photosynthesis.

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12 Excitation pressure modulates the redox potential of QB in photosystem II reaction centres SANE, P.V., IVANOV, A. G., POCOCK, T., KROL, M., OQUIST, G. 1

,

#HUNER, N. Department of Biology, University of Western Ontario, London, ON N6A 5B7, I Umea Plant Science Centre, Department of Plant Physiology, University ofUmea, Umea, Sweden S-901 87 A common feature of fluctuations in temperature, irradiance and nutrient status is exposure to excess light energy

or high excitation pressure. Photosynthetic organisms sense excitation pressure through modulation of redox status of the plastoquinone pool and the transthylakoid pH gradient. Antenna quenching through the xanthophyll cycle is one important mechanism to dissipate excess energy non-photochemically to protect photosystem II (PSII). However, antenna quenching can not account for all of the nonphotochemical quenching capacity. Thermoluminescence monitors charge recombination between electron acceptors and donors within PSII reaction centres. Using this technique, we show that the redox potential ofQB shifts to values closer to that ofQA upon exposure to high excitation pressure in Synechococcus, Chlamydomonas reinhardtii and Arabidopsis thaliana. This is a completely reversible phenomenon which increases the probability of PSII charge recombination and dissipation of energy under any condition that causes the accumulation of reduced QA. This is called reaction centre quenching. A bioenergetic model is presented to explain how adjustments in the redox potential ofQB enables the photosynthetic reaction centre to dissipate excess energy nonphotochemically and minimize photodamage.

13 Regulation of Light-harvesting complex gene expression: insights into the photoacclimation mechanisms in Chlamydomonas reinhardtii DURNFORD, DION, PRICE, JULIE, McKIM, SARAH & SARCHFIELD, MICHELLE Department of Biology, University of New Brunswick, P. 0. Bag Service 45111, Fredericton, N.B. E3B 6£1 To compensate for increases in photon flux density (PFD), photosynthetic organisms are able to photoacclimate, meaning they possess mechanisms for reversibly modulating their photosynthetic apparatus that brings light harvesting and utilization back into balance to minimize photodamage. The genes encoding components of the photosynthetic apparatus are encoded by both nuclear and chloroplast genomes; therefore, this process requires a coordinated expression of genes within different cellular compartments. The light-harvesting complex (Lhc) genes form a nuclear multi-gene family and are tightly regulated in response to changes in the light environment. In Chlamydomonas reinhardtii, an increase in PFD causes a predictable reduction in the amount of chlorophyll and light-harvesting complexes (LHC) per cell over the course of 24h. The expression of different members of Lhc gene family-Lhcb, Lhcb4, and Lhca- were examined and the mRNA abundance of all declined by approximately by 75% within the frrst I to 2 h of high light exposure. The mR.NA abundance did, however, soon recovered to their low light (LL) concentrations within 6 to 8 h even though LHC protein levels continued to decline. The mechanisms underlying these dynamic responses were determined to be a combination of transcriptional regulation and changes in mRNA stability. Although there are short-term alterations in transcription and transcript stability, the long-term acclimation of the light-harvesting antennae to HL occurs primarily at the translationaVpost-translationallevel.

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14 Photosynthetic acclimation under environmental and developmental constraints CAMPBELL, DOUGLAS A. Department of Biology, Mount Allison University, Sackville NB, E4L 1 G7, dcampbell@mta.ca Photosynthesis in natural communities occurs within constraints imposed by nutrient limitations or developmental programs, that limit organismal potentials for acclimation. At the cellular level intragenerational acclimation involves re-allocations of protein resources within existing cells, and so can function even in non-growing cells. In contrast intergenerational acclimation is a growth dependent process involving generation of new cells through division. We have recently studied three contrasting cases of photosynthetic acclimation. In lichens long-lived, non-dividing algal cells show an extreme example of intra generational acclimation through large reallocations of macromolecular resources, to maintain photosynthetic performance under a wide range of temperature and light. In the salt marsh grass Spartina in the Bay of Fundy, a rapid developmental program pre-empts photosynthetic performance in mid-summer, even though environmental conditions are favourable. The eutrophilic, fast-growing cyanobacteria Synechococcus sp. PCC 7942 shows complex, interacting responses to inorganic carbon, nitrogen and light levels through both intra- and intergenerational acclimation. In Synechococcus the composition of the photosynthetic system is most strongly influenced by carbon and nitrogen levels, whereas changes in light provoke short-term physiological responses.

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Plenary Lectures

15 Tales of fish and forests: Paleolimnology and nutrient dynamics SMOL, J.P. 1

, FINNEY, B.P.2, GREGORY-EAVES, 1. 1

, DOUGLAS, M.S.V.3 & SWEETMAN, J. I 1 Paleoecological Environmental Assessment and Research Laboratory ( P.E.A.R.L.), Department of Biology, Queen's University, Kingston, Ontario, Canada; 2 Institute of Marine Science, University of Alaska Fairbanks, Fairbanks, Alaska, USA; 3Paleoenvironmental Assessment Laboratory (P.A.L.), Department of Geology, University ofToronto, Toronto, Ontario, Canada Research on nutrient dynamics plays a critical role in our understanding of a wide spectrum of ecological and environmental issues. However, one of the major challenges that scientists face is the lack of long-term environmental monitoring data. Paleolimnology, the multi-disciplinary science that uses the physical, chemical, and biological data preserved in lake sediments, provides a method to reconstruct these missing data sets. Past nutrient levels in lakes can often be inferred in a statistically robust and ecologically sound manner using fossil diatom assemblages. For most ecosystem studies, it is generally assumed that nutrients travel "down hill" (e.g. runoff from agriculture). However, nutrients can also travel "up hill", when mediated by, for example, anadromous fish populations, such as Pacific sockeye salmon. New approaches have been developed that can track changes in the returns of adult spawners by using diatom and N isotope signatures preserved in nursery lake sediment cores. Not only do returning sockeye dramatically affect the ecology of their nursery lakes by nutrient release following spawning, but sockeye salmon are also integral to the terrestrial ecosystem (e.g. food for bears and scavengers) and ultimately as fertilizer for riparian vegetation. Using our diatom and isotope-based paleolimnological techniques, we have tracked sockeye salmon populations over 2 millennia, and have shown dramatic changes in populations that can be related to both human and natural causes.

16 Video microscopy of living diatoms PICKETT-HEAPS, J.D. School of Botany, University of Melbourne, Parkville, Victoria Australia 3052

For over 100 years, diatoms have been favorite objects for light and electron microscopy. We have been recording the behaviour of living cells at all stages of their life cycles, on video and mostly in time-lapse. This presentation is a preview of a video in final stages of production. The theme centers upon the remarkable ways these cells circumvent the numerous problems inherent in living in walls made of silica, whilst exploiting its refractory properties. Topics covered include cell organelles, motility, mitosis, cell division, morphogenesis of valves and spines, the mechanism of growth, secretion of chitin and adhesives, biofouling and sexual reproduction.

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Weresub Lecture

17 Micro-fungi and large buildings: What have air quality investigations taught us about micro-fungi? A mycologist's perspective

RAND, THOMAS Department of Biology, Saint Mary's University, Halifax, NS

Building contamination by fungi is clearly not a new problem. However, over the past decade fungi in indoor environments have become the focus of considerable research attention which has led to increased understanding of their significance in this environment. This presentation aims to describe some of the advances in our understanding of these indoor associated fungi.

Indoor air quality studies have illustrated that fungi are common and important constituents of indoor environments and that the composition of the building associated mycoflora is greatly dependent on building-material moisture content and composition. They have shown that the molds growing on wet building materials not only impact on the structural integrity of the building environment but also affect the comfort and health of the human occupants in ways different from those associated with outdoor mold exposures. This is because molds growing on building materials comprise a narrow group of toxin-producing species. The epidemiological signals are not associated with "mold" but rather toxin-producing species that are also allergenic. That indoor associated molds can lead to adverse health effects through mechanisms other than infection and allergic reactions is a newly evolving medical concept. Animal and cell culture studies have revealed that effects of exposure to these toxin producing fungi are manifest in both species- and strain-specific ways. Exposure outcome is also related to several components of the spores, including toxins, beta-glucan and pro teases additional to the physical damage resulting from inhalation of organic materials.

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Plant Canada - Contributed Oral Presentations

18 Growth promoting effects of the diazotroph Azorhizobium caulinodans on Canadian wheat cultivars ARCHAMBAULT, D.J., 11 ANYIA A.O., SLASKI, J.J. Environmental Technologies, Alberta Research Council, Vegrevil/e, Alberta, T9C 1 T4 Canada, Phone: (780) 632-8604, Fax: (780) 632-8620 Production of wheat typically requires intensive use of fertilizers. Reliance on fertilizers may be decreased by exploitation of plant growth promoting organisms. This work examines the responsiveness of Canadian wheat cultivars to inoculation with Azorhizobium caulinodans, a diazotroph isolated from the legume Sesbania rostrata. This bacterium has been shown to colonize wheat roots through crack entry. Inoculation of wheat cultivar CDC Teal grown in field soil caused increases in grain yield and total biomass of 34 and 49%, respectively. Inoculated plants produced more tillers and had greater leaf area than un-inoculated plants. A screening program has been initiated to establish whether the effects of inoculation are common within Canadian wheat cultivars. The parental lines of CDC Teal are being tested to identify the source of plant/microbe compatibility and crosses between responsive and non-responsive cultivars will be used to gain insight into the genetic complexity of compatibility. Nitrogenase activity is being measured to determine whether the observed effects can be attributed to nitrogen fixation. We have hypothesized that the observed effects may be caused by other growth promoting mechanisms. For example, we have observed changes in root morphology that may increase nutrient and water use efficiencies and drought tolerance.

19 Npq4-1 mutant of Arabidopsis thaliana exhibits altered photosystem photochemistry as measured by thermoluminescence *BALSERIS, A. 1

, KROL, M. 1, NIYOGI, K.K.2

, SAVITCH, L.V.3 & HUNER, N.P.A. 1

1 Department of Biology, University of Western Ontario, London, Ontario, N6A 5B7, Canada; 2 Department of Plant and Microbial Biology, University of California, Berkeley, Koshland Hall, Berkeley, California 94720, USA; 3 ECORC, Agriculture and Agri-Food Canada, Ottawa, Ontario, NJA OC6, Canada Photoautotrophs have evolved the capacity for antenna quenching of excess absorbed light by dissipating excess light non-photochemically (NPQ) as heat through xanthophyll cycle. The npq4-l mutant of Arabidopsis tha/iana lacks the capacity for antenna quenching. We show that npq4-l lacks PsbS, a protein required for NPQ, exhibits normal xanthophyll cycle activity but is more sensitive to photoinhibition than wild type (WT). However, the mutant shows no morphological differences compared with WT. Our hypothesis is that npq4-l may dissipate excitation energy by photosystemii (PS.II) reaction centre quenching which can be measured by thermoluminescence (TL). A shift in TL peak temperatures indicates a change in the redox potential of the recombining species. In the npq4-l mutant grown at 150J.LE and 20°C, the TL peak temperatures for S2QA. recombination were 17.6°C compared to 22.5°C and 34.2°C compared to 40°C for S2Q8 ' recombination in npq4-l and WT respectively. These data indicate a possible change in the redox potentials of both QA and Q8 in the PSII reaction centre of npq4-l. We suggest that this may reflect and increased probability for reaction centre quenching in the npq4-l mutant compared to WT.

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20 Folate synthesis in plants: The first step of the p-aminobenzoate branch is mediated by a bifunctional aminodeoxychorismate synthase 11BASSET, G., QUINLIVAN, E., RA VANEL, S., NICHOLS, B., ZIEMAK, M., GREGORY, J. &HANSON, A. PMCB, Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA p-Aminobenzoate (pABA), a precursor of the vitamin folate, is synthesized only in plants, fungi and microorganisms. In bacteria, it is formed through three enzymatic steps: First, a glutamine-amidotransferase (PabA) and an ADC-synthase (PabB) interact together to transfer the amide group of glutamine to chorismate, forming aminodeoxychorismate (ADC). Subsequently, an ADC-lyase (PabC) catalyses the elimination of the pyruvoyl group and aromatization yieldingpABA. In yeast and plants, the homologous PabA and PabB components are fused together, resulting in a bifunctional enzyme called 'pABA-synthase'. Because there are no obvious eukaryotic homologes of the PabC enzyme, the 'pABA-synthase' was assumed to be sufficient for de novo pABA biosynthesis. We identified an Arabidopsis eDNA specifying -94-kDa protein homologous to the yeast 'pABA-synthase', plus a typical chloroplast targeting peptide. This eDNA encodes a functional enzyme as demonstrated by complementation of both an E. coli pabA"B. double mutant and a yeast 'pABA-synthase' disruptant. However, in vitro the recombinant plant enzyme did not form any pABA unless the bacterial PabC enzyme was added to the assay. This demonstrates that the plant 'pABA-synthase' forms ADC and notpABA. We therefore propose to rename this enzyme ADC synthase.

21 Alkaloid biosynthesis in the sieve tube members of Papaver somniferum *BIRD, DAVID A. 1

, FRANCESCHI, VINCENT2 & FACCHINI, PETER J. 1

1 Department of Biological Sciences, University of Calgary, Calgary Alberta T2N 1 N4 2School of Biological Sciences, Washington State University, Pullman Washington 99164-4236 Two branch pathways ofbenzylisoquinoline alkaloid biosynthesis in opium poppy produce the pharmaceuticals morphine and sanguinarine. (S)-N-methylcoclaurine 3 '-hydroxylase (CYP808 1) is a P450-dependant monooxygenase operating in the common pathway leading to both alkaloids. In contrast, berberine bridge enzyme (BBE) represents the first committed step in the sanguinarine branch pathway, whereas the penultimate step in morphine biosynthesis is catalyzed by codeinone reductase (COR). Morphine is a major component of the alkaloid­rich latex in opium poppy. The latex is the cytoplasmic contents oflaticifers, which form an internal secretory system associated with the phloem. Previous studies have suggested that Jaticifers are the site not only of alkaloid accumulation, but also of biosynthesis. We have raised antibodies against CYP8081, BBE, and COR and used these to localize alkaloid biosynthesis in opium poppy. Our results show that morphine and sanguinarine biosynthesis occurs in the same cell type, which are sieve tube members. Moreover, we have localized the messenger mRNA of these genes to the supporting companion cells. Thus, not only is the latex not the site of alkaloid biosynthesis as previously suggested, we have shown that the sieve tube members, common to all higher plants, has the additional role of alkaloid biosynthesis in opium poppy.

22 Activity of the Arabidopsis HSPJ OJB promoter located in a nonautonomous Mutator-like element *BONHAM-SMITH, P.C., WILEN, R.W. 1 & YOUNG, L.W. Department of Biology, 1 Department of Plant Sciences, University of Saskatchewan, Saskatoon, SK, S7N 5E2 We have investigated the transcriptional activity of a 573 bp fragment of Arabidopsis HSPJOJ that is incorporated into a Mutator-Like Element (MULE) transposon. This MULE-HSPlOl has a high level of identity to the promoter, 5'UTR exon and ORF, but a lower level of identity within the 5'UTR intron of HSPJOJ. Collectively, the HSPlOl ORF, MULE 5' Terminal Inverted Repeat (TIR) and the 1.3 kb immediately upstream of the TIR was

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named HSP101B. Using RT-PCR, we have shown that the HSP101B ORF is strongly transcribed in the leaves and inflorescences of high temperature stress (HTS) treated Arabidopsis. Stable trans formants of Linum usitatissimum (flax) and Brassica napus (canola) as well as Arabidopsis plants transiently transformed with a HSP101B promoter:GUS construct showed both low temperature stress (LTS) and HTS induced or constitutive GUS expression. L TS induced transcription was due to four low temperature response elements in the HSP 101 B promoter sequence. Preliminary results suggest that an altered methylation pattern of the HSP 101 B:GUS trans gene may have been the cause of the altered regulation of transcription when compared to endogenous HSP101B activity.

23 Converging evidence that 4-aminobutyrate accumulation in plants deters invertebrate infestation and feeding .-11. ~ ;I) ~to oo \- 2.. @..:11-n

0 I 2 ~ I BOWN, A.W. & SHELP, B.J. 1Biological Sciences, Brock Univ. St Catharines ON; 1Plant Agriculture, Univ. of Guelph, Guelph ON In invertebrates 4-aminobutyrate (GABA) is an inhibitory neuromuscular transmitter, and many insecticides function as agonists or antagonists of the GABA gated chloride channel. Stress stimulated GABA accumulation in plants may function to deter insect feeding (Bown et al. 2002. Plant Physiol. 1430-1434). We have examined three

;sd: testable predictions of this hypothesis. 1 Ingested GABA will disrupt the normal growth and development of insect ~,~I!!~ larvae. 2. Larval activity on leaves will result in elevated GABA levels. 3. Transgenic plants with an enhanced

~(\"#\" capacity for stress stimulated GABA accumulation will deter feeding. The experimental data will be presented.

~~·~Q Theyar:;nsistentw~th~ehypothesis. ~phyll ~EVA~<-<-} a-\b~o-1.1 ~r eo~~

t ~'> ~ ~8>.: ~Cfi ' ~ ><td.,_ F cLbl\ '1 ,f.oo~ . ~ 1P 0 "<~" ?f ---~ ~"f,d. G.A-M "<J"K..:. ~t; , >- -'hoof _ .WW.~~ . ,.,~Jl.,..;,~ ~:~J-'24 p; ~~ pfW>~ J:o ~ ~nUiC/lll) c{ p.tok.})2.k <.n~ • .b,~ . r Structural and kinetic properties of a phosphate-starvation inducible intracellular purple

acid phosphatase from tomato suspension cells BOZZO, G.G. 1

, RAGHOTHAMA, K.G.3 & PLAXTON, W.C. 1•2

Departments of1 Biology and 2 Biochemistry, Queen's University, Kingston, ON, K7L 3N6; 3Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN Purple acid phosphatase (PAP) catalyses the hydrolysis of Pi from a wide range ofP-monoesters under acidic pH. Previously, we described the purification and characterization of two secreted monomeric PAPs (SAPl and SAP2) from the culture media filtrate Pi-starved (-Pi) of tomato suspension cells (Eur. J. Biochem. 269, 6278-6286). In the current study, Pi deprivation of the tomato cells for 8-d increased intracellular PAP (lAP) activity from 0.45 to 2.2 U•mg protein·• . lAP of -Pi cells was purified 262-fold to homogeneity and a final specific activity of 576 U•mg protein·'. Non-denaturing and SDS-PAGE and CNBr peptide mapping revealed that lAP is a 142 kDa heterodimer composed a 1: 1 ratio of structurally unrelated 63 and 59 kDa subunits. Similar to both SAPs, lAP spectral properties and insensitivity to tartrate inhibition indicate that it is a PAP. In contrast, lAP displayed a pH optimum of 5.1, and was heat labile. Although lAP exhibited wide substrate specificities, the enzyme exhibited efficient hydrolysis of various nucleoside di- and triphosphates. lAP demonstrated potent competitive inhibition by molybdate and fluoride, and mixed inhibition by Pi. lAP displayed significant peroxidase activity, which was optimal at pH 9.0, suggesting lAP to be a bifunctional protein. To our knowledge, lAP is the first heterodimeric PAP to be reported and is thought to function in the remobilization and scavenging of Pi from intracellular P-esters during Pi deprivation in tomato.

ABSTRACTS 13

25 An update and new chloroplast DNA information on phylogenetic relationships in the Caesalpinioideae (Leguminosae) *BRUNEAU, A., FOUGERE-DANEZAN, M. & FAUBERT, E.A. 1nstitut de recherche en biologie vegetale, Universite de Montreal, 4101 Sherbrooke est, Montreal, Quebec, H1X 2B2 Traditionally the basal subfamily Caesalpinioideae has been subdivided into five tribes, Cassieae, Caesalpinieae, Cercideae, Detarieae and Macrolobieae. Our recent cladistic analyses of chloroplast trnL intron sequences support the monophyly of Cercideae and of a broadly defined Detarieae that includes Macrolobieae. Cassieae and Caesalpinieae are considered to be polyphyletic, although several infrageneric groupings may be supported as monophyletic. These relationships are further supported with the addition of the sequences from the chloroplast trnL-F inter-genic spacer, and of morphological and anatomical data. However, several groups remain poorly resolved and relationships are sometimes ambiguous. In order to better resolve relationships in the Caesalpinioideae, and especially in tribe Detarieae s.l. that includes over half of the genera in the subfamily, we have examined the chloroplast matK and flanking trnK region. Preliminary analyses suggest levels of divergence among taxon pairs that are slightly lower than those obtained from the trnL intron and trnL-F spacer data, but with less homoplasy than the trnL-F sequences. The matK analyses overall support as monophyletic the same groups (e.g., Dialiinae s.l., Macrolobieae clade, Detarium group) as previously, but add resolution and increased support for other clades. Combined with information from nuclear sequences and morphological data, these analyses are contributing significantly to our understanding of phylogenetic relationships in the morphologically diverse, basal and paraphyletic subfamily Caesalpinioideae.

26 Insect attack and wounding induce traumatic resin duct development and terpene synthase gene expression in Sitka spruce BYUN MCKAY, A. 1

, HUNTER W. 1, TOUDEHFALLAH, M. 1

, DIGUISTINI, S. 1,

BOHLMANN, 1.2 & PLANT, A.L. 1

1 Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, B.C., V5A 1 S6. 2 Biotechnology Laboratory, Department of Botany, and Department of Forest Sciences, University of British Columbia, 237-6174 University Boulevard, Vancouver, B.C., V6T 1Z3 Conifer oleoresin is a complex mixture of monoterpene, sesquiterpene, and diterpene resin acids that provide both chemical and physical protection against browsing herbivores, pathogen attack, and stem boring insects. These terpenoids are produced through an electrophilic cyclization catalyzed by class-specific terpene synthases (TPS) to produce the mono-, sesqui-, and diterpenoid resin components. We have investigated whether genes encoding TPS are induced in Sitka spruce in response to simulated insect and actual attack by the white pine weevil, currently the most serious insect threat to both natural stands and plantations of Sitka spruce in coastal BC. We have used cDNAs encoding mono-, di-, or sesquiterpene synthases isolated from Sitka spruce to assess expression of the corresponding genes in response to simulated or actual weevil attack. Given the high degree of nucleotide sequence relatedness between TPS, PCR-based techniques are being used to discriminate between related TPS transcripts. A major goal of this research is to address whether induced TPS expression, as part of the induced resinosis response in spruce spp., contributes to resistance to the white pine weevil. Thus far our data suggest that induced TPS expression plays a significant role in the defense response deployed by Sitka spruce to insect attack and mechanical wounding.

14 Plant Canada 2003

27 Characterization of two pathogen-induced calmodulin-related proteins in Arabidopsis thaliana ·cHIASSON, D.M. & SNEDDEN, W.A. Department of Biology, Queens University, Kingston, ON, K7L 3N6 Calmodulin (CaM) is a highly conserved Ca2+ -binding eukaryotic protein which regulates a wide variety of cellular targets during Ca2+ signal transduction. Unlike most eukaryotes, plants possess a large repertoire of CaM-related proteins. The role of most of these proteins remains unknown and our lab is interested in elucidating their cellular functions. We have cloned and examined two CaM-like genes, AtAcre1 and AtAcre2, from the Arabidopsis genome that are highly homologous to a previously identified tomato gene, ACRE31 (Avr9/Qf-9 rapidly ~licited), which is upregulated during tomato host-pathogen incompatible interactions. Both AtAcre f.roteins contain three putative Ca2+-binding domains and undergo conformational rearrangement upon binding Ca +,similar to CaM. AtAcrel (23 kDa) and AtAcre2 (24 kDa) are larger than conserved CaM (17 kDa) and possess an extended N­terminus and a (predicted) flexible central helix region. Reverse transcription-PeR and GUS-reporter assays suggest that AtAcrel is expressed solely in the root cap, while AtAcre2 is expressed throughout the plant. Both AtAcrel and AtAcre2 were upregulated in rosette leaves in response to the pathogen Pseudomonas syringae pv. tomato (Pst) DC3000 (avrRpt2) which is avirulent on Arabidopsis Col-O. Genetic and biochemical data will be presented which suggest an important role for AtACREs in the plant immune response.

28 Targeted plant hormone metabolite profiling by liquid chromatography-electrospray ionization tandem mass spectrometry: A comparison of wild type and etrl-2 mutant seeds during seed dormancy and germination in Arabidopsis thaliana CHIWOCHA, SHEILA D.S. 1

, YANG, JENNY1, FEURTADO, J. ALLAN1

, ABRAMS, SUZANNE, R.2

, AMBROSE, STEVEN J. 2, CUTLER, ADRIAN J. 2

, ROSS, ANDREW R?, ZAHARIA, IRINA2

, GALKA, MAREK M.2, McCOURT, PETER3 & KERMODE, ALLISON

R.l 1 Department of Biological Sciences, Simon Fraser University, Burnaby, B. C. Canada V5A I S6. 2 Plant Biotechnology Institute, National Research Council of Canada, I I 0 Gymnasium Place, Saskatoon, SK Canada, S7N OW9. 3 Department of Botany, University of Toronto, Toronto, ON Canada, M5S 3B2 The ETR 1 gene encodes an ethylene receptor in Arabidopsis. The etr 1-2 mutation confers ethylene insensitivity and results in more dormant seeds than the wild type (WT). Endogenous levels of fifteen plant hormones and metabolites were analyzed by HPLC-ESIIMS/MS in WT seeds and compared to those of etr1-2 during dormancy and germination. Dormant seeds were imbibed (DI) under germination conditions or exposed to a moist chilling (MC) dormancy breaking period prior to incubation under germination conditions. WT seeds contained twice the amount of ABA compared to etr1-2. ABA declined in both DI and MC seeds, which was accompanied by slight increases in PA and ABA-GE in both genotypes. An initial increase in ABA after ld ofMC in etrl-2 was not observed in the WT. A further decrease in ABA during early germination in both genotypes was accompanied by noticeable increases in PA and ABA-GE, with PA increasing to a greater extent in the WT. GA3 levels were higher than GA. in DI seeds and during MC and both increased further during germination; however etr 1-2 contained three times and twice the amounts ofGA3 and GA., respectively, compared to WT. The cytokinin profiles ofDI and MC seeds were similar for the WT and etrl-2. During germination, zeatin riboside increased to a greater extent in WT seeds, while zeatin and isopentenyladenosine levels were similar. IAA levels were higher in DI seeds and after ld ofMC in the WT. IAA and IAAsp levels increased during germination, however, IAAsp accumulated to higher levels in etrl-2. These results indicate differences in levels of plant hormones and metabolites in WT and etr 1-2 mutant seeds during dormancy and germination in Arabidopsis.

ABSTRACTS 15

29 Multispecies point pattern analysis: Temperate and tropical forests DALE, M.R.T. & LEGENDRE, P. Department of Biological Sciences, University of Alberta, & Departement de sciences biologiques, Universite de Montreal We review a range of approaches to the analysis of multispecies point pattern and then focus on the use of a hierarchical set of six neighbour networks. In two sets of data, consisting of the locations and species of trees in eastern North American temperate forests, we found a significant tendency for neighbouring stems to belong to the same species, for most definitions of a tree's neighbours. In contrast, tree species in a tropical rainforest in Malaysia, while clumped at relatively small scales, did not exhibit a tendency to be network neighbours. The use of a hierarchy of neighbour networks provides greater insight into the spatial relationships among species. The examples illustrate the prevalence of nonstatwnarity in the forest communities studied by plant ecologists and the need to evaluate its affects on analysis and interpretation.

30 Interactions between Frankia and Paxillus involutus on a shared Alnus rubra host. DAY, MELISSA & MARKHAM, JOHN Department of Botany, University of Manitoba, Winnipeg, MB, R3T 2N2 Alnus rubra forms two simultaneous mutualisms with soil microbes: one with the nitrogen fixing actinomycete Frankia and one with the ectomycorrhizal fungus Paxillus involutus. Although much is known about the interaction between the host and each endosymbiont, little is known about the relationship between the two endosymbionts. To investigate this relationship, Alnus rubra was grown alone, with Frankia, with Paxillus involutus, and with both endosymbionts under 5 phosphorus/nitrogen conditions: OmM P-5mM N, 5mM P-5mM N, lOrn¥ P-5mM N, 5mM P-OmM N, and 5mM P-10 mM N. The changing phosphorous levels manipulated the Alnus rubra-Paxillus involutus system while the changing nitrogen levels manipulated the Alnus-rubra-Frankia system. Data will be presented on the response of one endosymbiont to manipulation of the other endosymbiont in an attempt to determine the nature of the relationship between Frankia and Paxil/us involutus on a shared host.

31 Whirly: a new family of plant transcription factors involved in disease resistance DESVEAUX, D.', SUBRAMANIAM, R.2, ALLARD, J. 1

, MESS, J.-N. 1, DESPRES, C.3

,

FOBET, P.3, SYGUSCH, J.\ DANGL, J? & #BRISSON, N.1

1 Dept. of Biochemistry, Universite de Montreal, Montreal, Qc.; 2 Dept of Biology, Univ. of North Carolina, Chapel Hill, NC; 3 Plant Biotech. Institute, NRC, Saskatoon, Sk Transcriptional activation of the potato defence gene PR-JOa involves the nuclear DNA binding protein PBF-2. PBF-2 is a homotetramer offour 24 kD subunits (p24), homologs of which are present in species throughout the plant kingdom. We have solved the crystal structure ofPBF-2 to 2.3 A resolution, revealing that the p24 protomers assemble to form a tetramer with cyclic C4 symmetry. Assembly of the protomers in PBF-2 produces a quaternary structure with a whirligig-like appearance, which inspired the name 'Whirly' for this family of plant proteins. Three genes with homology to p24 are present in the genome of Arabidopsis thaliana. Functional analysis of TILLING mutations in At Why 1, the Arabidopsis gene most similar to potato p24, indicates that the encoded protein plays a significant role in defence against the oomycete Pernospora parasitica. The eDNA for p24 encodes a protein of 30 kD with a predicted chloroplast transit peptide. Confocal microscopy of cells transformed with a p24-GFP fusion protein confirmed that p24 could localize to both the nucleus and the chloroplast. Moreover, the chloroplast localization of p24 is in the form of speckles that co-localize with chloroplast nucleoids. Our data suggest a role for the Whirlies in both the chloroplast and the nucleus.

16 Plant Canada 2003

32 Crataegus and Mespilus: two genera or one? DICKINSON, T.A., NGUYEN, S. & TALENT, N. Green Plant Herbarium (TRT), Center for Biodiversity & Conservation Biology, Royal Ontario Museum, Toronto ON M5S 2C6 and Department of Botany, University of Toronto, Toronto ON M5S3B2 Hawthorns and medlars are members of the monophyletic subfamily Maloideae in the Rosaceae. They appear to be sister genera, as they share both morphological and molecular characters that distinguish them from other genera in the subfamily. Prior to the description of the Arkansas endemic M. canescens by J. B. Phipps in 1990 Mespilus was monotypic, represented only by the Eurasian species M. germanica. In contrast, Crataegus is conservatively estimated to have over 200 species, distributed around the northern hemisphere, primarily, in temperate habitats. Both generic names go back to Theophrastus, and were recognized by both Tournefort and Linnaeus (and used almost interchangeably in the course of the 19th c.). Nevertheless, it is unclear whether the supposed differences between the genera are real, or are consequences at least in part of the way in which medlars have been cultivated for centuries, unlike most hawthorn species. Morphological comparisons of the two genera suggest that the variation exhibited by Mespilus is merely a subset of that seen in Crataegus. For this and other reasons it appears that continuing to recognize Mespilus as a distinct genus is unwarranted.

33 The status and ecology of Agalinis kingsii (Scrophulariaceae), a poorly known endemic to Grand Cayman, Cayman Islands, B.W.I. DIOCHON, A.C. & GARBARY, D.J. Department of Biology, St. Francis Xavier University, Antigonish, NS, B2G 2 W5 Approximately 80 island groups worldwide contain significant endemic floras (interpreted as five or more endemics) that are vulnerable to extinction due to their restricted geographic range and the pressures imposed by intensive land use for tourism and agriculture. Twenty-one of the 601 vascular plant species known from the Cayman Islands are endemic. Based on field work in 1999 we describe the ecology of one of these endemics, Agalinis kingsii Raf., which is restricted to two populations on Grand Cayman. One population of 43,000 plants is in a wetland within a nature reserve managed by the National Trust for the Cayman Islands; the second population has 500 plants and is on a private land parcel managed by the Cayman Islands government. This study provides a revised account of the morphology and taxonomy of A. kingsii and describes population structure, vegetation associations, and natural history of A. kingsii in the wetland nature reserve. While the wetland population appears stable, the results suggest that the structure of the vegetation community might be sensitive to minor changes in environmental conditions. Development in the surrounding area therefore has the potential to change the structure of the wetland community, potentially eliminating A. kingsii. Conservation strategies will be discussed.

34 Localization and physiological roles of thiol methyl transferases in relation to the glucosinolate-myrosinase defense system in plants *ETIENNE C., KOONJUL, P.K. & SAINI H.S. Institut de recherche en biologie vegetale, Universite de Montreal, 4101, Sherbrooke est Montreal, QC, H1X 2B2 Our group has recently described a novel class of plant enzymes- thiol methyltransferases (TMTs)- that constitute a putative third component of the glucosinolate-myrosinase defense system in Brassicaceae and other families. In the present work, spatial organization ofTMTs in relation to myrosinase in Brassica and Tropaeolum majus (nasturtium) was determined using in situ hybridization, immunolocalization and myrosinase activity assay on tissue imprints. In both species, the TMT transcript and/or protein were localized primarily in the phloem and to a lesser extent in the epidermis, paralleling the location of myrosinase. Two roles for TMTs have been postulated: detoxification of reactive thiols produced upon glucosinolate hydrolysis and production of volatiles that further

{

ABSTRACTS 17

defend the plant against pests. We found that plants and bacteria containing TMTs had greater tolerance to exogenously applied thiocyanate -a major glucosinolate hydrolysis product in Brassica. In addition, as TMTs can also methylate and volatilize halides, we tested their efficiency in detoxifYing these ions. TMT-containing organisms were indeed more tolerant to iodide ions. These results from ongoing experiments are consistent with the view that TMTs are part of the glucosinolate-based defense against pests and are involved in metabolic detoxification.

35 Response of the lichen Cladonia p/eurota to heavy metal deposition near Sudbury, Ontario FAHSELT, DIANNE & BACKOR, MARTIN Department of Biology, University of Western Ontario, London, Ontario N6A 5B7 The recovery of lichen communities on metal-rich historical ore-roasting beds west of Sudbury has been slow, and our objective was to compare the performance of the most frequently encountered lichen species, on the roast bed, in the stunted forest adjacent and in a control site 60 km upwind. Inductively coupled plasma-atomic absorption spectroscopy showed significantly higher concentrations of heavy metals in affected substrates than in the control site, and particulates incorporated into the thallus on or near the roast bed also contained high iron, aluminum, copper and nickel. Wavelength-dispersive x-ray spectrometry indicated potentially toxic levels of copper, nickel, iron and aluminum in both the mycobiont and photobiont of Cladonia pleurota, and samples collected on or near the roast bed showed decreased concentrations of chlorophyll a, chlorophyll b and total carotenoids. Chlorophyll a was subject to phaeophytinization and the yield of photosystem II, as measured by Fv/Fm, was significantly less in metal-rich sites. Experiments under controlled conditions indicated that copper was instrumental in changing physiological parameters such as pigment content and photosynthetic efficiency oflichens. Thin-layer densitometry and UV spectrophotometry showed no significant difference in the amount of usnic acid between affected and control sites, but collections from the roast bed area showed heavy metals associated with crystals of usnic acid, possibly forming complexes.

36 Population genetics of speciation in the Hawaiian endemic plant genus Schiedea FILATOV, DMITRY A. School of Biosciences, University on Birmingham, Edgbaston, Birmingham B 15 21T, UK The genus Schiedea (Caryophyllaceae) includes over thirty species endemic to Hawaii, and represents striking diversity in morphology, breeding system and habitat. This genus is a convenient model to study speciation process, since it represents one of the largest recent adaptive radiations with relatively well characterised biogeography. Here we report the level and the patterns of nuclear DNA diversity and divergence in the populations of S. globosa from Oahu and Maui islands. Unlike most other Schiedea species, S. g/obosa inhabits several islands in the Hawaiian archipelago. Phenotypic differences between the S. globosa plants from different islands suggest that populations of this species represent a case of on-going speciation due to colonization of several islands in the Hawaiian archipelago. Overall, the species-wide average heterozygosity per silent site (p) is relatively high, 0.3%. The silent DNA diversity on the older island of Oahu (p = 0.24%) is almost twice higher than on the younger Maui (p = 0.14%). Consistent with this, the haplotype phylogeny suggests a more recent origin of the Maui populations. Our data suggest that Oahu and Maui populations of this species are fairly isolated from each other (Fst = 0.57, P<O.OOO 1) and that the populations are sufficiently old to recover after the founder effect, which may have followed the colonization of the islands, and to accumulate phenotypic differences in isolation, supporting Mayr's model of allopatric speciation rather than founder effect speciation models.

18 Plant Canada 2003

37 Phylogenetic relationships among resin-producing Detarieae s.I. (Caesalpinioideae: Leguminosae) *FOUGERE-DANEZAN, M. 1

'2, MAUMONT, S.2 & BRUNEAU, A. 1

1/nstitut de Recherche en Biologie Vegetale, Universite de Montreal, 4101 Sherbrooke est, Montreal, Quebec, H1X 2B2 Canada; 2Laboratoire d'Ecologie Terrestre, Universite Paul Sabatier, Bat 4Rl//, 118 route de Narbonne, 31062 Toulouse cedex 4, France We use three different regions from chloroplast and nuclear DNA combined with morphological data to resolve relationships among the resin-producing genera of Detarieae s.l. Among the four tribes of the subfamily Caesalpinioideae (Leguminosae) Detarieae s.l., including Macrolobieae, is considered as monophyletic. These resin-producing genera of this tribe fall in two clades, the Prioria clade and the Detarieae s.s. clade, in previously published tmL intron analyses. But these analyses did not resolve relationships among those two clades, the Arnherstieae clade, and the genera Schotia and Barnebydendron. Phylogenetic analyses of the nuclear ITS and the chloroplast trnL-F spacer together with tmL intron data provide greater resolution. We combined molecular and morphological data to give a better support to our hypotheses. Although our results lack support concerning the monophyly of resin-producing Detarieae s.l., we suspect that the production of resins arose only once in Detarieae s.l. Recent taxonomic revisions are discussed from a phylogenetic perspective. Some of these revisions are strongly supported but others need further study. The two resin-producing clades are well represented in Asia, Africa and tropical America as well. Our results suggest a complex biogeographical history involving probable American­African exchanges via the North-Atlantic bridge and Asian-African exchanges via the Arabian peninsula.

38 Ecology of the invasive green alga Codium fragile: the 'oyster-thier is now the 'eelgrass­thier *FRASER, S.F. & GARBARY, D.J. Department of Biology, St. Francis Xavier University, Antigonish, NS, B2G 2W5 Growth of the invasive green alga Codium fragile was studied in estuaries in the southern Gulf of St. Lawrence, and a new prostrate growth form is described. Experiments were conducted at Caribou Harbour, Nova Scotia in which thalli were attached to plastic mesh in situ, and horizontal and lateral growth measurements were taken during 2001 and 2002. Horizontal axes of C. fragile elongated up to 30 em, and formed up to 120 upright laterals. Asexual reproduction by fragmentation was conspicuous in Caribou Harbour, and thousands of propagules were present in the intertidal and shallow subtidal zones in May-June. C. fragile typically attaches to hard substrata, such as a rocks or shells, and we quantified the different substrata at various locations in Nova Scotia and Prince Edward Island. In Caribou Harbour, about 30% of the drift plants were attached to rhizomes or shoot bases of Zostera marina (eelgrass) and had apparently removed the eelgrass from the substratum. Laboratory experiments conducted in a tank culture replicated many of the field observations. As C. fragile spreads through eastern Canada it may have an impact on population densities of Z. marina, a species experiencing major regional decline as a consequence of activity of the green crab, Carcinus maenus.

39 Observations on vascular bundles and resin canals in Lodgepole Pine FREDEEN, A.L. & MADILL, R.W. Ecosystem Science & Management, University of Northern British Columbia, Prince George, B.C. V2N 4Z9 New unopened buds were excised from lodegpole pine seedlings and trees of various ages in spring of2001 and 2002. Buds were obtained from different orders of branches, beginning with 0-order (terminal apical buds) to as far as 7th-order branches off of lateral branches. Transverse sections were made at 3-4 mm intervals along the apical buds and examined under an Olympus sZ40 dissecting microscope and images recorded using a mounted digital camera. The number of resin canals was counted in each section, and if possible, their relationship to the

ABSTRACTS 19

number of vascular bundles recorded. The data obtained will be related to previous work and hypothesis (Fredeen et al. 2002. CJB 80: 166-175) where tree-level phyllotactic direction in pine was found to be associated with direction of wood-grain angle.

40 Cadmium tolerance in Brassica species *GADAPATI, W. & MACFIE, S. Department of Biology, University of Western Ontario, London, Ontario, N6A5B7 Heavy metals, such as cadmium (Cd), are non-degradable, bioaccumulating and toxic. In view of the low cost associated with phytoremediation, a number of plant species are being screened for tolerance and hyperaccumulation and studied to understand the mechanisms of tolerance, which range from immobilization in roots and cell walls to intracellular binding to organic acids, proteins and peptides. Objectives of this study include correlating metal-accumulation and the production ofphytochelatins (PCs), cystein-rich polypeptides, with stress responses such as reduced biomass, apoptosis and reduced photosystem II efficiency in both Cd-tolerant B. juncea and Cd-sensitive B. nap us. Plants were grown hydroponically and treated with 0-200 _ M Cd for 4 days. The amount ofCd in the tissue and the PCs were quantified by ICP-OES and HPLC, respectively. While both the species accumulated the same amount of Cd, B. juncea produced four times more PC2 than B. napus. So, one expects B. napus to show more signs of stress. But, surprisingly, no significant differences in dry weight or photosystem II efficiency were noticed for either species during the 4 day exposure period. However, it is expected that differences will emerge when Cd exposure is for a longer period.

41 Patterns of rarity in the vascular flora of the Northern Rockies of Alberta *GOULD, J. 1

, MACDONALD, S.E.1 & BELLAND, RJ? 1 Department of Renewable Resources, University of Alberta, Edmonton, AB T6G 2H 1; 2 Devonian Botanic Garden, University of Alberta, Edmonton, AB T6G 2El Currently over 400 species of vascular plant are rare in Alberta however our detailed knowledge of the status of populations of these taxa is limited. Few species can be assessed each year therefore it is crucial that scientific methodologies be used to determine priorities for conservation of species and habitats. Our research is focused on examining patterns of rarity;-where do plants occur on the landscape, what factors are responsible for that and do rare plants co-occur as suites of species across the landscape? Field assessments of a number of different sites and habitats were conducted in the northern Rocky Mountains of Alberta in 2001 and 2002. The results of a series of multivariate techniques including cluster analysis (flexible beta), ordination (non-metric multidimensional scaling) and indicator species analysis suggest that some rare species do co-occur across the landscape and that there is a high fidelity to habitat. Other rare species appear to be distributed more independently across the landscape.

42 Metabolomic analysis of cold acclimation in Arabidopsis thaliana GRAY\ G.R., HEATH2

, D. & WHITEHEAD1, C.L.

1 Department of Biochemistry, University of Saskatchewan, Saskatoon, SK, S7N 5E5; 2 Phenomenome Discoveries Inc., 204-407 Downey Rd., Saskatoon, SK, S7N 4L8 Metabolomics is the study of the set of small molecules or metabolome, in a given tissue or organism. Non­targeted analysis of metabolites gives a direct insight into the actual components of a phenotype, which is a step beyond information generated by genomics and proteomics. Fourier Transform Ion Cyclotron Mass Spectrometry (FT-MS) has the highest mass resolution and accuracy to allow positive identification of metabolites, based on their masses. This unbiased approach was used to study the changes in metabolite levels in leaf samples of Arabidopsis tha/iana plants grown under varying conditions of cold acclimation, deacclimation, and cold reacclimation. The results of these metabolic phenotyping studies will be presented.

20 Plant Canada 2003

43 Molecular phylogeny of the tropical tree family Dipterocarpaceae provides evidence for a Gondwanic origin of Asian rainforest flora *GUNASEKARA, S. & DAY ANANDAN, S. Biology Department, Concordia University, Montreal, QC, H3G JM8 Despite long-standing debates, the evolution of high tree species richness in tropical rainforests remains poorly understood. It has been hypothesized that the ancestors of the majority of the far eastern tropical flora arrived from Africa via a south Asian Gondwana fragment (Deccan plate), dispersed into southeast Asia, and diversified during the last ten million years. To test this hypothesis, we performed molecular phylogenetic and phytogeographic analyses of Dipterocarpaceae, a pantropical tree family with high species richness in Asian rainforests. The taxa confined to Africa and Madagascar (Monotes and Marquesia) occupied a basal position, whereas species of the Asian forests formed terminal clades with relatively short branch lengths. The phylogeny, phytogeography, and fossil records are consistent with the hypothesis that Dipterocarps originated in Gondwana and spread to Laurasia via the Deccan plate, where their diversification gave rise to the present-day high species richness in far eastern rainforests.

44 Molecular phylogeny of Populus (Salicaceae) reveals reticulate evolution *HAMZEH, M. & DAY ANANDAN, S. Biology Department, Concordia University, Montreal, QC, H3G JM8 Species of forest tree genus Populus, collectively known as poplars, are widely distributed over the northern hemisphere, and well known for their ecological, economical, and evolutionary importance. Extensive inter-species hybridization and high morphological diversity of this group pose great difficulties for systematics and comparative evolutionary studies. In order to understand the evolutionary relationships of poplars and to provide a framework for biosystematic classification, we reconstructed the phylogeny of genus Populus based on DNA sequences of selected regions of the chloroplast and nuclear genomes. The resulting phylogenetic trees showed evidence for polyphyly of sections Tacamahaca and Aigeiros. The chloroplast DNA sequence of P. nigra was similar to that of species of section Populus, whereas nuclear DNA sequence data suggested close affinity of P. nigra to species of sections Tacamahaca and Aigeiros, suggesting a possible hybrid origin for P. nigra. Incongruity between nuclear DNA- and chloroplast DNA-based phylogenetic trees suggest reticulate evolution in genus Populus.

45 Expression of a vaccine protein in plants using a geminivirus-based replicon system HEFFERON, KATHLEEN L. Cornell Research Foundation, Cornell University, 20 Thornwood Dr., Ithaca, NY. USA. 14850. klh22@cornell.edu Edible vaccines produced in plants successfully evoke an immune response through oral immunization. They are relatively inexpensive, safe and easy to produce. In the past, edible vaccines have been generated from both transgenic plants as well as plant viral vectors. Either system has its own advantages and limitations. In this study, we have taken the best attributions of both systems and designed a minimalized version of the Bean Yellow Dwarf Gemini virus (Be YDV)-based replicon consisting of the cis-acting elements required for Be YDV replication as a means to express foreign genes in plant tissues at high levels. We present here a refmed geminivirus-based replicon system which possesses a versatility superior to other systems presently available. Construction of an expression cassette encoding a vaccine gene and analysis of expression levels of a novel vaccine protein in a plant system is described.

ABSTRACTS 21

46 Functional characterization of a phosphate-starvation responsive serine/threonine protein kinase from Arabidopsis thaliana *HETU, M.-F., HANNOUFA, A., MALBOOBI, M.A., TREMBLAY, L.J., TRUESDELL, P.F. & LEFEBVRE, D.D. Department of Biology, Queen's University, Kingston, ON, K7L 3N6 The mechanisms of plant response to nutrient limitation are of great interest for agricultural reasons. A novel Arabidopsis thaliana phosphate starvation-responsive gene, Atpsr 1, encoding a serine/threonine protein kinase, was cloned and expressed using the Escherichia coli pGEX-His expression system. AtPSRl contains a unique acidic C-terminus of unknown function. Its transcription was induced by P;, S04, and N deprivation in root tissue. Myosin heavy chain was identified as a general substrate for GST-AtPSRl. GST-AtPSRl kinase activity assays using MHC and l 2P-A TP revealed autophosphorylation and phosphorylation of a 25 kDa protein on serine residues. Eight mutations were generated and analyzed for their effect on GST-AtPSRl activity. Mutations that lowered activity included: a mutation in the ATP-binding site, a mutation upstream from the catalytic activating segment, and deletion of 47 amino acid residues from the distal C-terminus. Mutations that had no effect on activity consisted of: a mutation at a conserved aspartic acid in the active site and mutations at three potential phosphorylation sites. Notably, when a conserved lysine in the ATP-binding site was changed to glutamic acid, it increased the activity by 70%. Modeling using crystal structures derived from PKA and JNK3 was employed to simulate possible functional effects of this mutation.

47 Host specificity and growth of kelp gametophytes (Phaeophyceae) symbiotic with filamentous red algae (Ceramiales, Rhodophyta) HUBBARD, C.B. & GARBARY, D.J. Department of Biology, St. Francis Xavier University, Antigonish, NS, B2G 2W5 Kelp gametophytes were previously observed in nature living endophytically in red algal cell walls. Here we examine the interactions of two kelp species and six red algae in culture. Gametophytes of Nereocystis luetkeana became endophytic in the cell walls of two red algae, and grew epiphytically in high abundance on two further species. A/aria esculenta from the Atlantic coast of Nova Scotia became endophytic in five of the six species used in the experiment. This is the first evidence that gametophytes of an Atlantic kelp can become endophytic. The endophytic gametophytes were smaller and grew more slowly than gametophytes epiphytic on the same host Some red algal cultures were treated with phloroglucinol before infection to thicken the cell walls. Treatment with 0.1 % phloroglucinol in medium for at least two weeks led to increases in wall thickness of 53-400% in three species and enhanced the development of endophytic growth. The dramatic effect of phloroglucinol provides a basis for a mutualistic symbiosis between kelp species and the red algae. We hypothesize that the phlorotannins released by kelp sporophytes provide protection from UV radiation for the red algae, and that the red algae with their thickened cell walls provides an enhanced substratum for endophytic growth of the kelp gametophytes.

48 A mutated cellulose synthase-like gene and its impact on cell growth and seedling development in Arabidopsis thaliana GALWAY, M.E. 1

, BROWN, K. 1, MAGILL, T.2

, SCHIEFELBEIN, J.W.3 & WASTENEYS, G.0.2

1 Dept. of Biology, St. Francis Xavier University, Antigonish, NS; 2 Plant Cell Biology Group, Research School of Biological Sciences, Australian National University, Canberra, Australia; 3 Dept. of Biology, University of Michigan, Ann Arbor, MI, USA Two root hair-specific mutants isolated in independent screens of chemically mutagenized seed proved to be alleles and were designated rhd7-J (1. W. Schiefelbein) and rhd7-4 (G. 0 . Wasteneys). The rhd7 mutations are new alleles of the cellulose synthase-like gene AtCSLD3 (csld3 and kojak). Root hair cell walls rupture during

22 Plant Canada 2003

outgrowth, before the transition to tip growth occurs. Wound callose deposition is followed by recovery and tip growth in approximately 40% of ruptured cells, although tip growth stability is greatly reduced in these survivors. However, both rupture and tip growth instability was inhibited in a subset of hairs produced by seedlings growing at 5° C. Seedlings with mutations in both AtCSLD3 and the cellulose synthase gene AtCesA (required for primary cell wall synthesis) grew slowly and did not thrive, indicating an unexpected role for AtCSLD3 in whole seedling growth and development.

49 Destruction of eelgrass (Zostera marina) beds in Nova Scotia by the invasive green crab, Carcinus maenus GARBARY, D.J., MILLER, A.G., SEYMOUR, N. & WILLIAMS, J. Department of Biology, St. Francis Xavier University, Antigonish, NS, B2G 2W5 Zostera marina (eelgrass) is an important primary producer in many estuaries and shallow harbours of eastern Canada where it forms the dominant biotic feature. Personal observations of many sites and telephone interviews with experienced observers show that over 31 harbours representing at least 44 km2 of eelgrass have undergone major decline in Nova Scotia since the mid 1990s. In Antigonish Harbour during 2001 many areas that were previously occupied by lush eelgrass meadows were reduced to bare sediment containing dead rhizomes. We attribute the eelgrass decline to digging activity of the invasive green crab, Carcinus maenus, that reached population densities of385,000 crabs km2 in Antigonish Harbour in 2000. During the summer of2002 we observed the decline of eelgrass by over 75 % during a two-month period in Tracadie Harbour when a control site with few crabs (Caribou Harbour) showed increasing shoot density. These results were obtained based on direct observation of plant density, caging experiments in which crabs were either included or excluded, and a mark­recapture experiment of eelgrass shoots. The collapse of eelgrass in Antigonish Harbour during 2001 resulted in a decline of migrating Canada Geese by about 50 %, and we anticipate more significant impacts as the eelgrass decline becomes more widespread.

50 Environmental influences on phi thickening occurrence in gymnosperm roots GERRATH, J.M. 1

•2, PURICH, M.2 & MATTHES, U.2

1 Department of Biology, University of Northern Iowa, Cedar Falls, /A, 50614-0421, USA; 2Department of Botany, University of Guelph, Guelph, ON N1G 2W1 Although we had shown that the occurrence of phi thickenings (lignified wall thickenings in the radial and tangential walls of the root cortex that resemble the letter_ in cross section) is correlated with gymnosperm systematics, their function remains unknown. The objective of this study was to test the hypothesis (borne of anecdotal evidence) that phi thickenings could be induced under environmental conditions favoring lignification; namely, a) water saturation, b) the presence of a fungal (mycorrhizal) association, and c) soil compaction. Seedlings of Cryptomeria japonica (phi thickenings present), and Pinus aristata and P. rigida (phi thickenings absent under mesic conditions) were grown under conditions described above, and harvested after four months. Root/shoot lengths were measured, and anatomical sections were used to determine occurrence of mycorrhizal fungi and phi thickenings. Results showed that the treatments had highly significant effects on root morphology and root/shoot ratios. In C. japonica the ratio of phi area/root area was significantly less in seedlings grown in wet, compact soil, demonstrating that phi thickening development responds to the environment. Phi thickenings could not be induced in the Pinus seedlings, indicating that phi thickening occurrence is a robust systematic character.

ABSTRACTS 23

51 Estimation of seed bank and seed viability of the Gulf of Saint Lawrence Aster (Symphyotrichum /aurentianum) *KEMP, J.F. & LACROIX, C.R. Department of Biology, University of Prince Edward Island, Charlottetown, Prince Edward Island, CIA 4P3 The Gulf of St. Lawrence Aster, Symphyotrichum laurentianum, is a member of the family Asteraceae and is listed as a plant under "special concern" according to COSEWIC (Committee on the Status of Endangered Wildlife in Canada 2002). This rare and vulnerable halophyte is found in only a few locations in New Brunswick (NB), Prince Edward Island (PEl), and the Magdalen Islands, Quebec. As an annual, Symphyotrichum laurentianum relies exclusively on its seeds to survive to the next generation. The purpose of this study was to determine the number of viable S. laurentianum seeds in the persistent and transient seed banks at selected sites in PEl and NB. A transient seed bank refers to a short term storage of seeds that are produced at the end of a growing season and are viable until the following growing season. Any seeds that are dormant and survive to subsequent growing seasons are considered to be in the persistent seed bank. Results show that there are very few seeds in either the transient or persistent seed banks and that the greatest concentration of the seeds was found near the surface of the soil. In addition, only a small proportion of those seeds tested positive for viability based on Tetrazolium staining. Population estimates were also conducted at the four known sites in the PEl National Park. All sites showed signs of decline based on population estimates dating back to 1993. The Covehead Pond site showed the greatest decline from 250-300 individuals in 1993 to only l 0 individuals in 2002. Further protection and monitoring of this plant is critical for its survival.

52 The recovery of plains rough fescue grasslands from livestock grazing in Riding Mountain National Park, Manitoba

. # *KENKEL, N.C., OTFINOWSKI, R., SLOGAN, J., TROTTIER, G.C. Department of Botany, University of Manitoba, Winnipeg, MB, R3T 2N3 Rough fescue grasslands occupy less than 5% of their former Canadian range, and most remaining areas have been disturbed by livestock grazing and haying. In contrast with other prairie grasses, summer grazing of plains rough fescue (Festuca hallii (Vasey) Piper) leads to its displacement from the plant community and increased dominance by non-native species. While the impacts of livestock grazing on fescue grasslands are well documented, their long-term recovery from grazing is poorly understood. In this project, we illustrate the recovery of fescue grasslands 26 years after the removal of livestock from Riding Mountain National Park. During 1995, we examined the plant community and soil from 33 permanent transects established within the park's fescue grasslands in 1973. Despite the long absence of disturbance, plant and soil composition were correlated with historic grazing intensities. Discriminant analysis models illustrated that heavily grazed transects remained dominated by non-native grasses and forbs, and were characterized by high levels of macronutrients and pH. Our analyses suggests that the recovery of fescue grasslands from grazing may be inhibited by the presence of non­native species, and that heavily disturbed areas may act as nuclei for the establishment and invasion of non-native species.

53 Highly selective and remotely controlled transcriptional down regulation of anther invertases during water-stress-induced male reproductive failure in wheat KOONJUL, P.K., MINHAS, J.S., NUNES, C., SHEORAN, I.S. & #SAINI, H.S. Institut de recherche en biologie vegetate, Universite de Montreal, 4101 rue Sherbrooke est, Montreal, QC, HIX 2B Water deficit during male meiosis in wheat causes pollen sterility, thus reducing yield. Our search for causes of this failure revealed that water stress impairs the activities of vacuolar and cell-wall invertases in anthers prior to the

24 Plant Canada 2003

arrest of pollen development. We now present the following evidence that the effect is highly selective and is transcriptionally regulated: (i) Other related enzymes remained unaffected. (ii) Invertase was inhibited only by stress occurring around meiosis. (iii) Stress discriminated between invertase genes: RNA gel-blot analysis of three invertase genes isolated from anthers showed that, among floral organs, the genes were expressed preferentially though not exclusively in anthers. Their developmental expression patterns paralleled those of the activities of the respective invertase isoforms. Semi-quantitative RT-PCR demonstrated that water deficit inhibited the transcription of two of the three genes- one encoding the vacuolar and the other a cell-wall isoform- without affecting the second cell-wall gene. Western blot analysis showed that invertase protein amount declined, and tests ruled out the role of an inhibitor in impairing invertase activity. (iv) In situ hybridization revealed that only the genes expressed in microspores were affected. Using published information, we propose that these effects are remotely regulated from outside the anthers.

54 Biochemical and molecular characterization of plant thiol methyltransferases- a putative third component of glucosinolate-based defense system KOONJUL, P.K, ATIIEH, J., DllANA, R., ETIENNE, C. & SAINI, H.S. Institut de recherche en biologie vegetale, Universite de Montreal, 4101, Sherbrooke est Montreal, QC, H1X 2B2 Members of Brassicaceae and several other families contain an anti-herbivory defense system, made up of glucosinolates and a separately compartmentalized enzyme myrosinase. Herbivore attack brings the two in contact, hydrolyzing glucosinolates into a variety of toxic thiols that defend the plant. We recently described a novel group of plant enzymes- thiol methyltransferases (TMTs)- that methylate these thiols. Several of the resulting methylated products are volatile with proposed functions in plant-pest interactions. Five TMT isoforms were purified from Brassica o/eracea, and they had distinct molecular masses, pH optima and kinetic properties towards various thiols. Two slightly differing genes encoding the dominant isoform were cloned. The TMT genes and proteins they encode are structurally and functionally distinct from conventionally known N-. 0- or S­methyltransferases. Their transcript levels were highest in younger plant tissues, paralleling the known distribution of glucosinolates. An active recombinant protein produced by expressing a TMT eDNA in E. coli displayed characteristic properties of the native thiol methyltransferases. The TMT genes and the antibody raised to the recombinant protein, along with the t-DNA insertion mutants are being used to determine the spatial organization and physiological role of TMTs in relation to the glucosinolate-myrosinase system.

55 Regeneration Dynamics of interior Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco. var. glauca (Mayr) Franco) in Canada's four mountain parks *LASTRA, R.L. & KENKEL, N.C. Department of Botany, University of Manitoba, Winnipeg, Canada R3T 2N2 The regeneration dynamics of interior Douglas-frr were examined in Canada's four mountain parks (Banff, Jasper, Yoho and Kootenay National Parks). Three environment-stand types (xeric, mesic and hygric) were delineated from two hundred and twenty study plots. Results indicate that available soil moisture and nutrients, incident solar radiation, and fire history are strong determinants of stand structure and composition. Regeneration dynamics (seed germination, seedling establishment and sapling survivorship) are affected by available understory light, soil moisture, and seed source proximity. Douglas-frr forms self-perpetuating open groves in xeric, nutrient-poor sites. Recruitment is generally restricted to mesic microsite refugia; saplings growing in exposed areas are highly suppressed. Regeneration dynamics are most variable in closedcanopy mesic sites. Within these stands, seedling/sapling growth is favored under canopy gaps. In closed-canopy hygric sites, poor seedbed conditions and reduced understory light levels are strongly detrimental to the establishment and survival of interior Douglas-fir seedlings/saplings. These findings suggest that the persistence of Douglas-fir in Canada is ultimately dependent on factors such as disturbance frequency and severity, species vital attributes and, site characteristics.

ABSTRACTS 25

56 Estimating the required trans-cambial carbohydrate flux and lateral permeability coefficient of sieve cell membranes using observed rates of wood growth in Abies ba/samea LEE, D.R. 1 & RIDING, R.T.2

1 Biology Department, Memorial University of Newfoundland, St. John's, NL. A 1 B 3X9. 2 Biology Department, University of New Brunswick, Fredericton, NB. E6B 6EJ A study of phloem structure coincident with an investigation into the growth oftracheids of the fir tree (Abies balsamea) has permitted an estimate to be made of the required trans-cambial carbohydrate flux required to sustain observed rates of wood growth. The cambium lays down xylem derivatives toward the interior of the tree, and all nutrients required for the synthesis of the new cells, virtually all tracheids in balsam fir, must be supplied to these developing tissues from the carbohydrate supply in the long distance translocation tissues of the phloem. These carbohydrates must leak laterally from the sieve cells through the sieve cell membrane, and make their way across the cambial zone for incorporation into the wood. The I 0-14 days taken by tracheids for cell expansion, primary and secondary cell wall formation and complete differentiation, permits these estimates to be made.

57 Phloem of the fir tree (Abies balsamea) is a dynamic multi-year tissue LEE, D.R. 1 & RIDING, R.T.2

1Biology Department, Memorial University of Newfoundland, St. John's, NL. AlB 3X9. 2 Biology Department, University of New Brunswick, Fredericton, NB. E6B 6El The frr tree (Abies ba/samea) is an evergreen of the northern temperate forest which retains the needles for periods from 4 to 7 years. The phloem of the balsam fir is a multi-year complex tissue which undergoes a methodical series of anatomical changes as it ages. The phloem exhibits annual rings comparable to those found in the xylem, with the rings of sieve cells 5 - 7 cells wide. They are demarcated from the previous years functioning phloem by the axial parenchyma, a tannin filled band of cells laid down at the time of the fall equinox. One to three rows of sieve cells are laid down after the formation of the axial parenchyma in the fall. The phloem ring is completed in the spring during cambial reactivation. Two complete bands of continuous phloem cells are evident on the trunk. In the third year phloem, air spaces develop with the rupture of the continuous band of phloem at phloem rays. In the fourth and subsequent years the spaces are filled by the ray parenchyma proliferating and becoming transformed into sclerids. Within the 4 to 7 year bands the phloem sieve cells are crushed and replaced by sclerids in a time frame coincident with the life expectancy of the needles.

58 The regulation of one-carbon (Cl) metabolism in Arabidopsis thaliana LI, R., MOORE, M. & #KING, J. Department of Biology, University of Saskatchewan, Saskatoon, SK., S7N 5E2 Tetrahydrofolate (THF)-dependent Ser biosynthesis in C3 plants can occur from either of two Cl pathways: From Gly via a glycine decarboxylase/serine hydroxymethyltransferase (GDC/SHMT) route or from formate via coupled Cl -THF synthase/SHMT activities. Two questions were posed in this study. Ql: Does formate dehydrogenase (FDH) activity influence formate pool size in cells and redirect formate-derived Cl units away from Ser formation towards C02 release? Q2: Does the supply ofCl to Ser biosynthesis via the lesser Cl-THF/SHMT pathway increase if the dominant GDC/SHMT route is impaired? Answer to Ql: Transgenic Arabidopsis plants with a 3-to 5-fold overexpression ofFDH had the same pool size of formate, synthesized the same amount ofSer but gave off twice as much 13C02 as did WT plants when fed [13C]formate. Conclusion: The detoxification offormate to C02 by FDH is the primary and preferred fate of this organic acid. Answer to Q2: We used a GDC-deficient mutant (glyD family) of Arabidopsis, which accumulated 25% less Ser from supplied {_-13C]Gly than did WT plants. The amount of [13C]Ser formed from [13C]formate was 2.5-fold greater in glyD than in WT plants. Conclusion: The Cl-THF/SHMT pathway can compensate for impairment of the primary GDC/SHMT pathway of Ser biosynthesis, but only partially.

26 Plant Canada 2003

59 The palisade layer of soybean seed coats determines their permeability properties MA, FENGSHAN1

, PETERSON, CAROL A. 1, GIJZEN, MARK?

1 Department of Biology, University of Waterloo, Waterloo, ON N2L 3G 1, and 1 Southern Crop Protection and Food Research Center, Agriculture and Agri-Food Canada, London, ON N5V 4T3 Seed coats of soybean [Glycine max (L.) Merr.] display a wide range of water permeabilities, depending on the cultivar. While a low permeability is beneficial to seed survival under certain conditions, a high permeability is desired in the food processing industry. Hence, an understanding of soybean seed water permeability is biologically and commercially important. The palisade layer, which is the outermost cell layer of the seed coat, has been assumed to be critical, but the actual control point of water entry into the layer has not been properly defined as yet. In this project, tests of seed permeability were performed and compared to the structural features of the seed coats. It was found that cuticles isolated from the outer tangential walls of the palisade layer of an impermeable seed coat were stronger than those of a permeable one. Analyses using electron microscopy showed that the former were also thicker than the latter. In addition, permeable seed coats tended to have naturally occurring cracks. Presence or absence of depressions on a coat did not have any clear connection to its permeability. Epi-cuticular waxes were present in all cultivars examined; therefore, they did not appear to be a determinant of differential permeability among the cultivars. Taken together, palisade cuticles are the main, if not the only, factor that determines the permeability properties among soybean cultivars. In the future, cutin synthesis and its regulation will be investigated.

60 Effects of canopy manipulation on understory plant communities: A synthesis from the western boreal forest MACDONALD, E., MOURELLE, C., DANKERT, B. & FENNIAK, T. Department of Renewable Resources. University of Alberta. Edmonton, AB, CANADA T6G 2E3 In forests, canopy trees have a controlling influence on the abundance, diversity, and composition of understory plants. We examined the response of understory plant communities following several different types of canopy manipulation. Partial harvesting of aspen-white spruce mixed wood forests lead, in the short term, to reduced understory richness and diversity per plot while the composition became more similar to that found under a pure aspen canopy. Selective harvest of canopy aspen from forest with a white spruce understory lead to increased species richness at the plot scale but reduced beta diversity (species turnover among plots), resulting in unchanged diversity at the stand scale. Salvage thinning of old ( l 00+ yrs) lodgepole pine forests resulted, in the short term, in increased understory species richness per plot and beta diversity. Commercial thinning oflodgepole pine (-80 yrs) lead, in the longer term, to reduced understory richness per plot but higher beta diversity. Increased resource availability arising from reduced canopy density could result in either lower or higher understory richness, depending on the pre-treatment resource availability, community, and competitive interactions. The understory composition will change as the understory environment varies spatially and temporally; within-stand heterogeneity in the understory environment will determine how beta diversity changes.

61 Carbon status strongly constrains light acclimation in cyanobacteria *MACKENZIE, T.D.B. & CAMPBELL, D.A. Biology Department and Coastal Wetlands Institute, Mount Allison University, Sackville, New Brunswick, E4L 1 G7 We tested how inorganic carbon concentration (Ci) and temperature interact to affect the amplitude ofacclimatory changes in Synechococcus PCC7942 in response to increased light. Cells grown at low Ci (c. 0.1 mmol) had similar electron transport rates but lower antenna:core pigment ratios and slower growth compared to high Ci cells (c. 4

ABSTRACTS 27

mmol). Cellular pigment concentrations, while sensitive to Ci, changed less than l 0% in either treatment group in response to increased light, while growth slowed transiently after the light increase. High Ci cells recovered to increased growth and oxygen evolution rates, but the low Ci cells only maintained rates at or below levels from before the light shift. Lower temperature generally slowed growth and dampened the acclimatory shifts in high Ci cells. Across the light shifts high Ci cells showed stable PSII and PSI antenna cross sections, qp, and NPQ levels. In contrast low Ci cells showed increases in PSI cross section and NPQ across the light shifts. Upon an increase in light, high Ci allowed cells to increase flux through a stable electron transport system to exploit the increase in light. In contrast, under low Ci cells reorganised their electron transport system, presumably through disproportionate increase in PSI excitation, to cope with but not exploit the increase in light intensity.

62 Predictors of growth and mortality of natural regeneration across the Canadian boreal forest *MA TIHIAS, L.A. & KENKEL, N.C. Department of Botany, University of Manitoba, Winnipeg, MB, R3T 2N2 To further our understanding of longitudinal variation in boreal stand dynamics, this study characterizes differential growth and mortality of established natural regeneration of trembling aspen (Populus tremuloides Michx. ), balsam flr (Abies balsamea (L.)), white spruce (Picea glauca (Moench) Voss), and black spruce (Picea mariana (Mill.) BSP) across the Canadian boreal forest over a three year period. Sites of advance regeneration were established in the spring of 2000 at seven locations across the Canadian boreal forest ensuring a western, central, and eastern representation of each species. Approximately 500 saplings for a given species were monitored in each region. Sapling survival and various indices of growth and vigour were recorded each year. Competition by surrounding vegetation was estimated for each sapling, and numerous stand-level measurements were taken. Trembling aspen is the only species to have demonstrated appreciable mortality. Factors governing growth and mortality for each species may exhibit differences among geographic regions. Results can be used to develop fleld indicators for predicting growth and mortality of preserved advance regeneration following harvesting. By examining regeneration dynamics through large-scale comparisons of contemporaneously established survey sites across the country, this study will contribute to more unifled theories of boreal stand development.

63 Post-transcriptional photoacclimatory mechanisms in Chlamydomonas reinhardtii *MCKIM, SARAH & DURNFORD, DION Department of Biology, University of New Brunswick, P. 0. Bag Service 45111, Fredericton, N.B. E3B 6E1 Although light capture fuels growth and development of photosynthetic organisms, excess light absorption severely damages photosynthetic structures. Survival depends on responding appropriately to changes in light condition such light absorption is balanced by energy use. Photoacclimation is an important mechanism that mitigates potential imbalances by a series of reversible short- and long-term physiological responses. Our laboratory has characterised the photoacclimation response of the green alga, Chlamydomonas reinhardtii, following an excess­light stress. We have examined photoacclimatory down-regulation of the light-harvesting proteins (LHCIIs) that surround and funnel absorbed energy into photosystem II (PSII). Following exposure to excess-light stress, LHCIIs are initially down-regulated at the level of transcription; however, transcription is only transiently repressed as Lhc mRNA rebounds to pre-stress levels within 6 to 8 hours while LHCII protein levels continually decline suggesting that during photoacclimation, the LHCs are partially regulated by translational control. We examined polysome association of the Lhcbl transcript (encoding a LHCII protein) and determined that a shift from low to excess-light effects a transient polysome off-loading, indicating that translation is down-regulated as the cell acclimates to excess-light. Further examination of translational regulation is ongoing.

28 Plant Canada 2003

64 Survey and assessment of Kouchibouguac National Park's exotic flora: Towards the development of a management stratery *MAZEROLLE, D.M. 1

, VASSEUR, L & TREMBLAY, E.2

1 Universite de Moncton, Pav. P.A. Landry, Moncton, NB E1A 3£9 1 Kouchibouguac National Park of Canada, N.B. North Field Unit, 186 Route 117, NB E4X 2P 1 The spread of exotic invasive plants constitutes a significant problem for native biodiversity and ecosystem conservation worldwide. In Canada, many national parks are currently addressing this threat to their ecological integrity. The objectives of this study were to examine the exotic flora ofKouchibouguac National Park and to develop a management strategy for exotic invasive species. Fieldwork was comprised of two major components, an assessment of invasives in several disturbed and vulnerable sites and an exotic flora inventory. Threats to park ecosystems were identified and prioritized following these surveys. Thirty sites were chosen randomly for inventory, five from each of six categories of habitat: fields, dunes, campgrounds, roadsides, trails and new trails under construction. Sites were sampled using series of sixty 1m2 quadrats arranged along five transects. Forty-two species were added to the park's known flora, thirty-two of which are exotic. Diversity indexes for every category of habitat, as well as average percentages of native, exotic and exotic invasive species indicate that field sites are most susceptible to have greater numbers of exotics while roadsides have greater diversity. Ordinations revealed associations between site characteristics and species composition on which assessment and management strategies can be based.

65 Why is Caulophyllum thalictroides (L.) Michx. (Berberidaceae) rare in Nova Scotia? *MOXSOM, D.M. 1

, HILL, N.2 & GARBARY, D.J. 1

1 Department of Biology, St. Francis Xavier University, Antigonish, NS, B2G 2 W5; 1 Department of Biology, Mount Saint Vincent University, Halifax, NS Cau/ophy//um thalictroides is a rare herbaceous perennial in Nova Scotia. The reproductive biology and ecology of this species was investigated to determine habitat preferences and to establish the causes of rarity. Natural seed set was about 42%, suggesting that pollination is not a limiting step. Many seedlings occurred adjacent to mature plants confirming seed viability. Seeds were not recovered from either bear or raccoon scat, and we suggest that biotic dispersal is a limiting factor in the establishment of new populations. Soil and vegetation analysis was conducted comparing floodplain hardwood sites with C. thalictroides to neighboring upland hardwoods to examine the possibility of restricted habitat Soil chemistry is an important factor in determining habitat. High amounts of the elements calcium, magnesium and manganese are found in floodplain sites where C. thalictroides is located, compared to low levels of calcium, magnesium and manganese in upland soils. Principal component analysis concluded that species composition of the vegetation is not a good determinant of habitat for C. thalictroides. Floodplain forests and soil chemistry are the best determinants of habitat.

66 Establishment, regeneration niche interactions and facilitation succession among six boreal bryophytes MULLIGAN, ROISIN C. & DALE, M.R.T. Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T6G2E7 The ability of six boreal bryophytes (Sphagnum angustifolium, S. fuscum, S. mage//anicum, Pleurozium schreberi, Ptilium crista-castrensis and Aulacomnium palustre) to establish from gametophytic fragments on natural burnt peat medium in peatland and botanic garden settings over two years was examined. Sphagnum fuscum did not regenerate in any treatment and its present distribution in this peatland may be the result of past facilitation by

ABSTRACTS 29

colonist bryophytes. Sphagnum magel/anicum failed to grow where planted, however; its appearance in other treatments at the peatland suggests colonisation via sexual diaspores.

Sphagnum angustifolium regenerated with good success in all treatments and appeared via sexual or asexual diaspores in many others. Pleurozium schreberi and Ptilium crista-castrensis grew successfully where planted. Aulacomnium palustre established with high frequency as a planted and unplanted species. Prolific growth of unplanted acrocarpous colonist and fugitive bryophytes suggests an important role for facilitation succession in post-fire bryophyte peatland communities. Between the two years of the study the unplanted, r-selected colonists increased in frequency partially at the expense of the planted K-selected species and this decline is attributed to an absence of specialisation in the latter for expansion in hostile post-fire habitats.

67 ITS evolution in Crataegus and related Maloid genera NGUYEN, S. & DICKINSON, T.A. Department of Botany, University of Toronto, Toronto, Ontario, and Centre for Biodiversity and Conservation Biology, Royal Ontario Museum, Toronto, Ontario North American black-fruited hawthorns (Crataegus sections Douglasianae and Brevispinae) form a phenetically defined group within the genus, and include I 0-stamen polyploid species and 20-stamen species that may be diploid or polyploid. In order to test whether this group is monophyletic, an ITS phylogeny was obtained for seven taxa from Doug/asianae and Brevispinae, and 13 species from eight other sections. ITS sequences from Mespi/us, Malus, and other Maloid genera were included as outgroups and used to root the trees. The ITS!, 5.8S and ITS2 regions of nrDNA were amplified and sequenced. Sequences were aligned using Clustal X and phylogenetic analysis was carried out using PAUP. Amplification and sequencing ofiTS from these 20 diploid and polyploid Crataegus species confirm earlier indications of ITS polymorphism. Two ITS variants were found and cloned for C.rivularis, C. spathulata and C.suksdorfii. One of these variants contains a TATA motif in ITS! that is lacking in the other variant. Subsequently, the TATA variant of ITS has been found in 12 species, including five black-fruited Crataegus. The consensus maximum parsimony tree for the ITS sequences (Crataegus including both variants, plus outgroups) shows Mespi/us, the putative sister genus ofCrataegus, to be nested within Crataegus.

68 Fungal succession on leaves decaying in streams - Traditional and molecular approaches *NIKOLCHEVA, L.G. & BARLOCHER, F. Department of Biology, Mount Allison University, 63 B York St., Sackville, NB, Canada E4L JG7 Leaf disks from linden, red maple and beech as well as birch wood sticks were submerged in a stream in Nova Scotia for 10 four-week periods. Fungal biomass (ergosterol content), plant mass loss, conidial production and fungal species richness were highest in August and September and lowest in February. A total of 57 species of aquatic hyphomycetes were identified. The community evenness was lowest in the summer when conidial production was dominated by Anguillosporafiliformis and Flagellospora curvula. Conidial diversity did not depend on the substrate. The fungal community DNA was isolated and the ITS region from fungi was amplified. Denaturing gradient gel electrophoresis (DGGE) and terminal restriction fragment length polymorphism (T-RFLP) identified 43 and 47 fungal phylotypes, respectively. Community phylogenies showed that the presence or absence of phylotypes was dictated by the season while the abundance of each phylotype was dictated by the substrate. Sequencing of the fungal phylotypes determined that they were close to Helotiales, Erysiphales, Onygena1es, Dothideales and Diaporthales (Ascomycota) and Tremellales (Basidiomycota). Both traditional and molecular techniques are essential for a balanced view of fungal succession in streams.

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69 Are all disturbances equal? Disturbance and regeneration potential in balsam fir forests *NOEL, L.J. & HERMANUTZ, L.A. Department of Biology, Memorial University, St. John 's, NL, A 1 B 3X9 The production of a dense advanced regeneration is key to the future health of balsam fir forests. To determine the factors responsible for the failure of balsam frr forest regeneration in Eastern Newfoundland, seedling emergence and survivorship were studied. The effects of seedbed, soil temperature and moisture, and herbivory were compared in experimentally seeded plots within anthropogenically disturbed areas (selective cuts, domestic harvested plots) and naturally disturbed areas (unbroken stands and insect-killed plots). Natural regeneration levels were compared by sampling juvenile (2-15 yrs) density among disturbance types. Seedling emergence and persistence were highest in natural disturbances. Mature unbroken stands contained the highest densities of juveniles and the lowest level of herbivory. Both insect kills and selective cutting experienced low seedling success due to suboptimal seedbed composition and high herbivory levels. Domestic wood harvest plots closely mimic unbroken stands, and contain high densities of naturally regenerated balsam fir seedlings because the canopy and seedbed composition are relatively unaffected. Herbivory by non-native slugs was an important source of seedling mortality. Disturbance regime is directly linked with seedling success and persistence. Clearly, to implement sustainable forest management, natural disturbance patterns must be more closely mimicked to ensure survival of early life history stages.

70 A comparison of vegetation - soil relationships in saline and non-saline landscapes in Alberta's boreal forest PURDY, B.G., MACDONALD, S.E. & LIEFFERS, V.J. Department of Renewable Resources, University of Alberta, Edmonton, AB T6G 2Hl The relationship between plant communities and soil salinity was studied along transects from flooded wetlands to upland forest vegetation zones in the boreal forest of Alberta within landscapes having different levels of salinity and one reclaimed oil-sand mining landscape. Three natural groupings based on levels of soil salinity were found: strongly saline, moderately saline and non-saline landscapes. In saline landscapes, the flooded, wet meadow and dry meadow plant communities at lower elevations along transects were quite different from those found in non­saline landscapes. These plant communities were associated with saline surface soils (10-20 em). For boreal landscapes, vegetation zones with surface soil salinity were found to harbour communities similar to those found in prairie saline habitats. With increased elevation along transects, surface soil salinity decreased, and the plant communities between saline and non-saline landscapes became similar. Soil salinity was still high in saline landscapes at higher elevations where forest vegetation grew, though here the salinity was restricted to soils at depth (80-1 00 em). That forest vegetation can grow in environments high in salts leaves much hope for oil-sands reclamation since the production of saline habitats is of a major concern to the oil-sands industry.

71 Trans vs cis: the role of cytokinin isomers during pea embryogenesis *QUESNELLE, P.E. & EMERY, R.J.N. Biology Department, Trent University, Peterborough, Ontario, K9J 7B8 Many of the most active and abundant cytokinins in plants can exist in the trans or cis isomer configuration. It is widely believed that trans isomers are the major and active forms based on cytokinin profiling and traditional bioassay activity. However, emerging molecular and physiological evidence implicates a role for cis-cytokinins, especially during legume seed development. The paucity in understanding the importance of cytokinin form and activity during seed development is demonstrated in pea. Pea was an historical anomaly as no cytokinins had been identified in seeds of any pea genotype, although seeds of other species were rich sources of these hormones. Here we used histology to precisely document four developmental stages of early pea embryogenesis and report the predominance of cis-cytokinin forms. Seed tissue components (testa, embryo, endospermic fluid) were extracted and purified to isolate 12 cytokinins for quantification by HPLC-(+) electrospray tandem mass spectrometry (LC-

ABSTRACTS 31

MS-MS). While cytokinin composition was found to vary within seed tissues, cis-Zeatin Riboside (cis-ZR) predominated throughout development. We will discuss cis-ZR activity in comparison to the trans-isomer as assessed by an in vitro bioassay we developed involving the cultured growth of excised embryos.

72 The folate precursor p-aminobenzoate is reversibly converted to its glucose ester in the plant cytosol QUINLIVAN, E.P. 1

, ROJE, S.2, BASSET, G.2

, SHACHAR-HILL, Y.3, GREGORY, J.F. 111 1 &

#HANSON, A.D.2

1Food Science and Human Nutrition Department and 2Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611, USA; 3 Plant Biology Department, Michigan State University, East Lansing, MI 48824, USA Plants synthesize p-aminobenzoate (pABA) in chloroplasts and use it for folate synthesis in mitochondria. It has generally been supposed that pABA exists as the free acid in plant cells. Here we show that leaves of various plants and tomato fruits readily convert supplied pABA to its _-D-glucopyranosyl ester (pABA-Glc). HPLC analysis indicated that much of the endogenous pABA in leaves and fruits is esterified, and that the total pool ofpABA (free plus esterified) varies greatly. UDP-glucose: pABA glucosyltransferase activity was detected in fruit and leaf extracts and the reaction was found to be freely reversible. pABA-Glc esterase activity was also detected in extr­acts. Subcellular fractionation indicated that the glucosyltransferase and esterase activities are cytosolic. These results show that reversible formation ofpABA-Glc in the cytosol is interposed between pABA production in chloroplasts and pABA consumption in mitochondria. As pABA is a hydrophobic weak acid, its uncharged form is membrane-permeant and it's anion is consequently prone to distribute itself spontaneously among subcellular compartments according to their pH. Esterification of pABA eliminates such errant behavior, and may provide a readily reclaimable storage form of pABA as well as a substrate for membrane transporters.

73 Pea transformation and the use of root organ cultures to study mycorrhizal symbiosis RANEE, MEHTA N. & #GUINEL, FREDERIQUE C. Department of Biology, Wilfrid Laurier University, Waterloo, Ontario, N2L 3C5. A natural genetic transformation of plants by the soil bacterium Agrobacterium rhizogenes produces the hairy roots condition characterized by adventitious roots proliferation at the infection site. It is caused by genetic material transfer from A. rhizogenes to the infected plant cells. The transferred DNA, located on a large root-inducing plasmid, becomes stably integrated into the plant genome, and controls the growth and differentiation of the transformed tissues. A. rhizogenes-transformed roots are able to grow readily in culture without hormone addition. Transformed roots provide a useful system for studying the development of structures resulting from root-microbe interactions; those of legumes are especially useful because not only do they form mycorrhizas but they are also capable of forming nodules when associated with rhizobia. Here, a root organ culture of pea (Pisum sativum) is established where transformed pea roots are used as hosts for the growth of the mycorrhizal fungus Glomus intraradices. Fungal propagation was successful because fungal sporulation was obtained. A pea nodulation mutant known to be ethylene over-sensitive and cytokinin over-producer has also been transformed. Its ability to form transformed roots will be discussed; its ability to form mycorrhizas in vitro will be compared to that of transformed wild-type and of non-transformed pea mutants.

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74 Influence of heavy metal contaminated soil on plant biomass turnover RYSER, PETER & SAUDER, WENDY Department of Biology, Laurentian University, Sudbury, ON, PJE 2C6 We investigated the effects of sublethal heavy metal levels on plant growth and leaf lifespan. For this purpose, two heavy metal contaminated soils were collected near Sudbury, ON and diluted with silica sand in a logarithmic series to volumetric soil concentrations of 112 to 1/64. Rosettes of the hawkweed Hieracium pilosel/oides, collected from a non-contaminated site, were planted in pots filled with the soil-sand mixtures in June 2002. We hypothesized that both growth and leaf lifespan would decrease with increasing concentrations ofheavy metals. Initial results supported this hypothesis, but by September, leaf lifespan of plants growing in metal contaminated soil was higher. This was caused by a positive correlation between reproduction of the plant and leaf turnover: the plants flowered intensively, and seed ripening was associated with the senescence of leaves attached to that stem. Metal contaminated soil delayed the flowering and reduced the flowering intensity, thus slowi.ng down biomass turnover. Effects were found even at low contamination levels. The results suggest that low levels of heavy metals may dramatically influence plant life history and biomass turnover. This is likely to have consequences for the species' population dynamics, species composition of a community, and ecosystem processes.

75 Density, recruitment, growth, and survival of the invasive green alga Codium fragile ssp. tomentosoides in tidepools on a rocky shore in Nova Scotia, Canada SCHMIDT, A.L. & SCHEIBLING, R.E. Department of Biology, Dalhousie University, Halifax, NS, Canada BJH 4Jl Since it was first recorded in Nova Scotia in 1991, the invasive green alga Codiumfragile ssp. tomentosoides has spread rapidly in shallow subtidal and intertidal habitats along the Atlantic coast. Density, size structure, growth and survival of Codium were monitored in 2000, 2001, and 2002, in three tidepools at differing tidal heights at Cranberry Cove, Nova Scotia. Recruitment of Codium (plants~ 2 em in length) occurred in spring and summer, resulting in large increases in population density. Differences in the timing of recruitment between years were associated with differences in the dominant mode of reproduction: dispersing propagules in 2000 and regeneration of damaged thalli in 2001 and 2002. Growth of individually marked thalli averaged between, 6.2 and 16.9 em in 4 months (June to September) and was not correlated with temperature variation within and between pools. Survival rates of these plants were consistently low (~ 20% by October) among pools and between years. Codium was transplanted into microhabitats of differing wave exposure where the overall loss of plants was not found to vary. Differences in wave exposure and grazing pressure did not explain the observed patterns of survival. These fmdings indicate that Codium is particularly resistant to physical and biological disturbances, which accounts for its invasive success.

76 Hurricanes, "Periwinkles" and the mystery of the missing (sea?) grass: The disappearance of seagrass beds in a large tropical inland lagoon SCHUEGRAF, MONICA Faculty of Environmental Studies, York University, Toronto, Ontario Pearl Lagoon is a 520 km2

, tropical inland lagoon on the Caribbean Coast of Nicaragua. Pearl Lagoon is home to the macrophytes Ruppia maritima and Najas guada/upensis. These grass beds have played an important role as an aquatic nursery for many shrimp and fish species on which local people are dependent for food. As recently as 15-25 years ago Pearl Lagoon contained huge patches of"mananti grass", the two previous mentioned species. Today there are only 2 medium-sized and 4 or 5 small patches. Accessing traditional ecological knowledge (TEK) and using sediment coring, the historical distribution of these grasses are reconstructed. The primary hypothesis for macrophyte loss are three hurricanes that have successively hit or influenced the Pearl Lagoon watershed in the last 15 years. Other possible causes of seagrass loss are herbicide input carried by three large rivers, increased sedimentation due to deforestation, increases in salinity due to a canal created in 1979 and increased

ABSTRACTS 33

eutrophication. Further research is required to determine how much each factor contributed to macrophyte loss, and whether or not the grass can be replanted, or if the conditions promoting growth have been lost. Community members were vital members of the research team and are interested in seeing and participating in continuing research.

77 Phylogeny and hybridisation in the Rosa blanda-Rosa woodsii complex STARR, J.R., JOLY, S., & BRUNEAU, A. Institut de recherche en biologie vegetale (IRBV), Universite de Montreal, 4101 rue Sherbrooke, Montreal, Quebec, H1X 2B2 Rosa blanda Ait. is a common diploid (2n=14) rose distributed along thickets and rocky slopes throughout Eastern North America, west to Saskatchewan. Often easy to identify by its nearly thornless habit, numerous variants have nonetheless been identified and distinguished as species (R. johannensis, R. rousseauiorum, R. williamsiz). The status of these taxa is, however, controversial. Most authors treat them as either synonyms or varieties, whereas others believe that they may represent hybrids between R. blanda and other eastern species. In central North America, in a zone covering roughly Southern Manitoba, the Dakotas, Iowa and Minnesota, R. blanda comes in contact with the most eastern elements of R. woodsii, a closely related western diploid that can normally be distinguished from R. blanda by its typically ample stem armature. However, a seemingly intergrading morphological series of populations across this area led Erlanson (1934) and Lewis (1962) to conclude that they must be the product ofhybridisation (i.e., R. blanda X R. woodsii = R. X dulcissima). In this study we use DNA sequences and amplified fragment length polymorphisms (AFLP) to examine the relationships of Eastern North American roses, with the purpose of clarifying the taxonomic status of the R. blanda segregates, and the hypothesis that an extensive R. blanda/R. woodsii hybrid zone is present on the northern Great Plains.

78 What can phylogeny tell us about the systematic utility of fruit epidermal silica bodies in the genus Carex (tribe Cariceae; Cyperaceae)? STARR, J.R. 1

, WATERWAY, M.2 & BRUNEAU, A. 1

Institut de recherche en biologie vegetale (JRBV), Universite de Montreal, 4101 rue Sherbrooke, Montreal, Quebec, H1X 2B2, & Macdonald Campus, McGill University, 21,111 Lakeshore Road, Ste-Anne-de-Bellevue, Quebec, H9X 3 V9 Since the 1970's, fruit epidermal silica bodies have become an integral part of systematic studies in Carex (c. 2000 spp.), with uses ranging from the circumscription of species to the delimitation of sections. Early studies suggested that these characters were conserved, although conflicts with traditional classifications have since questioned their systematic utility. These conclusions, however, were largely drawn from poorly circumscribed Carex groups before the wide application of modem phylogenetic techniques in the Cariceae. In this study we re-evaluate the utility of these characters within the context of the recent morphological and molecular phylogenies of Carex, Uncinia and tribe Cariceae. Patterns of silica body variation in the genus Uncinia parallel the positive and negative conclusions drawn regarding their systematic utility in Carex. Silica body groups often conflict with traditional classification, large taxa, such as sections, could not be defined, and the morphologies of distant taxa were sometimes identical. However, silica bodies are generally consistent with the circumscription of small, well-defmed clades in both genera. Moreover, Carex wide analyses demonstrate that silica bodies can sometimes be useful for circumscribing sections, and they are often ideal for circumscribing species. Unfortunately, problems with homology assessment and a lack of discrete characters indicate that silica bodies are best used for species circumscriptions, and as external data sets for evaluating relationships based on more conserved characters.

34 Plant Canada 2003

79 Molecular relationships of Elymus tetraploid species and its donor species SUN, GENLOU & MCMILLAN, ERIN Department of Biology, Saint Mary's University, Halifax, Nova Scotia, BJH 3C3, Canada Elymus genus in the tribe Triticeae contains approximately !50 widespread species worldwide. Elymus species are exclusively allopolyploids having two or three of the five basic genomes (S, H, Y, P and W) in different combinations. The S genome is considered the pivotal genome of Elymus because it is found in all species. Taxonomy of Elymus is extremely complex because of the highly morphological variation within and between species, the polyploid origin of the genus, and the frequent spontaneous hybridization between species. Molecular relationships of Elymus tetraploid species and its donor species were examined using RFLP-PCR of chloroplast genes. The cpDNA regions from 38 individuals of 16 species representing SH, SP and SY genomes and Sand H genome donor species were amplified by the polymerase chain reaction (PCR) with five pairs of primers designed from chloroplast genes, and digested with up to 16 different restriction enzymes. Cluster analysis based on a similarity matrix using the UPGMA algorithm separated the 38 individuals into two distinct groups. The result shows that the maternal parent or donor species of the chloroplast genome is from the'S' genome represented by the genus Pseudoroegneria.

80 Evaluating the physiology of near-isogenic lines of durum wheat that differ in response to cadmium (Cd) *SWEENEY, M.N. & MACFIE, S.M. Department of Biology, The University of Western Ontario, London, ON, N6A 5B7 Near-isogenic lines of Triticum turgidum var durum differ in accumulation and translocation of Cd. By the end of the life cycle, one line accumulates nearly two-fold the concentration ofCd in shoots and grain relative to the other line. Several parameters including biomass, tissue concentration of Cd, fluorescence, chlorophyll content and fluorescence, organic acids and enzyme activity have been measured to elucidate the basis of this difference. Concentrations of Cd in shoot and root tissue increased, and root dry weight decreased, with 1 OmM Cd in solution. Chlorophyll a content decreased with treatment of Cd, but did not differ between the lines. Chlorophyll a fluorescence was 0.80 ± .01 across Cd treatments for both lines which is indicative of non-stressed plants. Concentrations of oxalate and t-aconitate in bulk shoot tissue of both lines did not vary. The concentrations of tartarate and malate increased in shoot tissue treated with Cd; the concentration of malate differed between the two lines only at 0.5mM CdCh. Preliminary analysis indicates that the activity of malate dehydrogenase decreases in response to Cd in the line that accumulates less Cd. Enzyme activity in dissected shoot tissue will be discussed.

81 Dynamic subcellular reorganization in response to infection of Arabidopsis by oomycete pathogens TAKEMOTO, D., JONES, D.A. & #HARDHAM, A.R Plant Cell Biology Group, Research School of Biological Sciences, Australian National University, Canberra, ACT 2601, Australia An early response of plant cells to pathogen attack is rapid cytoplasmic aggregation at the site of attempted penetration. We have used Arabidopsis plants expressing green fluorescent protein (GFP)-tagged genes to monitor the dynamic reorganization of micro tubules, micro filaments, ER and the Golgi apparatus in living plant cells after penetration by the oomycete pathogens, Phytophthora sojae and avirulent and virulent isolates of Peronospora parasitica. Infection by the non-pathogen, P. sojae, was arrested in the epidermal layer, whereas both isolates of P. parasitica grew into the mesophylllayer where avirulent hyphae triggered hypersenstive cell death. In epidermal cells adjacent to penetrating hyphae, actin microfilaments were re-arranged to form large bundles in cytoplasmic strands that focused on the penetration site. ER and Golgi bodies also accumulated, suggesting that production and secretion of plant materials were activated around the penetration site. In some cases, microtubules formed a global, circumferential array across cells surrounding the penetrating hypha. These changes in cytoskeletal and

ABSTRACTS 35

endomembrane organization occurred in response to non-pathogenic, avirulent and virulent oomycetes, but growth of only the non-pathogen was inhibited in the epidermis. This suggests that cytoplasmic aggregation is not a determinant of race-specific resistance but might be part of a basal resistance mechanism.

82 Ploidy level variation and breeding behaviour of Crataegus (Rosaceae): data from flow cytometry *TALENT, N. & DICKINSON, T.A. Center for Biodiversity and Conservation Biology, Royal Ontario Museum, Toronto, Canada M5S 2C6 and Department of Botany, University of Toronto, Toronto, Canada M5S 3B2 Hawthorns are known to vary in ploidy level (2x, 3x, and 4x individuals have been documented). Parallel variation in breeding system involves diploids with gametophytic self-incompatibility, and self-compatible polyploids in which gametophytic apomixis may occur. Investigation of ploidy level variation and breeding system has been hampered by the difficulty of obtaining chromosome counts. Flow cytometry, however, permits rapid measurement of DNA amount in nuclei from several tissues. Results are repeatable, and there is no ambiguity in measurements from known diploids, triploids, and tetraploids. Our initial samples are from southern Ontario but more southerly species and cultivated forms are also being measured. No plants with very high ploidy levels have so far been found. Tetraploids predominate, with some diploids and triploids. DNA amounts are indistinguishable within a ploidy level. Pollination experiments have suggested that apomictic seed production is pseudogamous (pollination is required for seed set, apparently because of its role in endosperm development). Flow cytometry of mature embryos, and of endosperm from developing seeds, suggests that ploidy levels higher than 4x are unlikely, and while triploid embryos are produced at a significant rate by some diploids pollinated from tetraploids, if the seed parent is tetraploid, then embryos are generally also tetraploid.

83 Patterns and implications of multiple autopolyploid origins in apomictic Easter daisies *THOMPSON, STACEY L., CHOE, GINA & WHITTON, JEANNETTE Department of Botany and Centre for Biodiversity Research, University of British Columbia How important is recurrent polyploid formation to the introduction of genetic variation within resulting lineages? We are tackling this question in the Easter daisy, Townsendia hookeri, a diminutive member of the Asteraceae. As Easter daisies comprise both sexual diploid and apomictic polyploid populations, the lack of recombination's confounding effects is a unique boon to this system. Firstly, to document the number and relationship among separate polyploid lineages, we have surveyed haplotype variation in two chloroplast DNA regions (portions of ndhF and matK-trnK) from 12 diploid and 25 polyploid populations throughout the species range. DNA sequencing of 1289 bp reveals 3 informative indels and 18 SNPs that distinguish 4 sexual and 7 polyploid haplotypes within T. hookeri. Phylogenetic analyses demonstrate a minimum of four separate polyploid origins. For three lineages, polyploids share identical haplotypes with diploids. One polyploid haplotype from Yukon's Kluane National Park is highly divergent from the rest of the species assemblage and may have descended from a northern refugium. Other Yukon haplotypes cluster within disjunct Alberta populations and likely represent post­glacial advance. ALFP analyses demonstrate that each Yukon population is polyclonal, allowing the impact of separate polyploid origins on this genetic variation to be explored.

84 Defining critical habitat for designated species *TILLEY, SUSAN & HERMANUTZ, LUISE Department of Biology, Memorial University, St. John 's, NL, A 1 B 3X9 To define the critical habitat of Braya longii (endangered) and B.fernaldii (threatened) as mandated by Endangered Species legislation the importance of unoccupied habitat was evaluated by determining capacity to support these species. To test the occupancy hypothesis, both substrate types in naturally disturbed occupied and unoccupied

36 Plant Canada 2003

habitat patches were seeded with the site-specific Braya species. In all situations, Braya seeds emerged and persisted into the fall, indicating that unoccupied sites are capable of supporting Braya. There was no substantial loss of seedlings to herbivory, indicating the long-term persistence in these sites is possible and may be of use in restoration efforts of these designated species. To test whether colonization of suitable but unoccupied habitats was limited by dispersal, the size of the soil seed bank, amount of seed rain, and distribution of natural seedling emergence was measured. Results indicated that the Braya seed bank is dispersed and variable and that seeds disperse within 50 em of the adult plant, suggesting that the distribution of both Braya species within and between sites is limited by dispersal. Based on this study, unoccupied but suitable habitat must be included as critical habitat for designated plants under both federal and provincial legislation.

85 Calmodulin-like proteins in the Arabidopsis genome and their roles in stress response *V ANDERBELD, B. & SNEDDEN, W.A. Department of Biology, Queen's University, Kingston, ON, Canada, K7L3N6 Calcium (Ca2+) is a ubiquitous second messenger that, in plants, is utilized by cells to transmit signals in response to numerous forms of stimuli, such as environmental stress. The molecular interpreters of these signals are Ca2+­binding proteins (CaBPs), the most abundant and well-studied of which is calmodulin (CaM). Whereas many organisms have only one form of CaM, the Arabidopsis genome encodes for a several closely related CaMs, as well as many divergent "CaM-like" proteins (CLPs). The question our lab is addressing is; why do higher plants such as Arabidopsis possess so many CLPs? We are currently investigating whether these CLPs function as Ca2+ sensors during stress response. As a step toward understanding this process, we have cloned more than 40 different CLPs from Arabidopsis and have examined their transcript expression patterns in plants subjected to various stress regimes (pathogen, salt, drought, abscisic acid and salicylic acid). Using high-throughput reverse-transcription PCR, we have shown that transcript levels of many CLPs accumulate specifically in response to certain stresses. These expression analyses, in conjunction with ongoing reverse genetic studies on transgenic knock-out plants, will be discussed in the context of Ca2+ signalling and stress physiology in plants.

86 Cloning and characterization of three Arabidopsis tha/iana NAD kinases: Identification of a calmodulin-binding isoform *WALLER, J.C., TURNER, W., V ANDERBELD, B., SNEDDEN, W.A. Queen's University Department of Biology, Kingston, ON, K7L 3N6 We report the first cloning and molecular characterization of an NAD kinase from a higher plant. NAD kinase is the only enzyme capable of synthesizing the coenzyme NADP. Interestingly, plants possess a calmodulin (CaM)­regulated NADK that has been implicated in roles such as pathogen response. CaM is a Ca2+-binding eukaryotic protein that modulates the activity of numerous enzymes. We have cloned cDNAs predicted to encode three NADK isoforms, designated AtNADK1, AtNADK2, and AtNADK3, respectively, from the model plantArabidopsis. These AtNADKs display significant protein sequence similarity with each other in their C-terminal regions and with other known NADKs. Recombinant AtNADKs expressed in E. coli all showed activity. Although native NADK was completely dependent upon Ca2+ and CaM for activity, none of the recombinant proteins showed responsiveness to CaM in vitro. However, using fusion constructs, we mapped a CaM-binding domain to a region within anN-terminal extension of AtNADK2. Antiserum raised against recombinant AtNADKl or AtNADK2 recognized immunoreactive proteins ofMWs -60 and 110 kDa in Arabidopsis extracts. The larger immunoreactive native protein bound to CaM-agarose in a Ca2+-dependent manner suggesting it is AtNADK2 whereas the 60 kDa immunoreactive protein is likely AtNADK1. Reverse-transcription PCR analyses suggests all three isoforms are expressed in all tissues throughout development. Kinetic properties of Arabidopsis native and recombinant NADKs will be presented and possible roles for CaM-dependent NADKs in plants discussed.

ABSTRACTS 37

87 Identification of Hsp90 interactors in plants *WANG, Z., ZHANG, Z. & KRISHNA, P. Department of Biology, University of Western Ontario, London, ON, N6A 5B7

The highly conserved and abundant molecular chaperone hsp90 plays a key role in signal transduction networks, cell-cycle control, protein degradation and protein trafficking. The number of identified client proteins whose functions are facilitated by hsp90 continues to grow, especially in animal systems. A critical dependence on hsp90 has been established for animal steroid hormone receptors and several serine/threonine and tyrosine kinases. Hsp90 is believed to serve as a capacitor for morphological evolution, and in recent years it has emerged as a promising drug target. The hsp90 protein family is largest in plants. Despite the availability ofhsp90 genes from a variety of plants, the identities of client proteins for plant hsp90 remain undefined. We have identified potential interactors of plant hsp90 in a yeast two-hybrid screen. These include cDNAs of Brassica napus encoding Rubisco small subunit, Hop (co-chaperone ofhsp90), FK506 binding pmtein, transcription factor-like protein, proteins containing tetratricopeptide repeat domain, ar.d a hormone receptor. Full-length cDNAs for a subset of these candidates have been obtained. We are currently in the process of confirming the specificity of protein interactions in vitro. These results will be discussed in the context of the hsp90 chaperone system in plants.

88 Role of carotenoids in the purple sulfur bacterium Thiocapsa roseopersicina *WILCOX, M. & MILLER, A. Department of Biology, St. Francis Xavier University, Antigonish, NS, B2G 2 W5 Thiocapsa roseopersicina is a photosynthetic bacterium, often found forming dense blooms within shallow salt ponds in Nova Scotia. In these ponds, T. roseopersicina can survive either under high irradiation, being exposed to direct sunlight, or under low irradiation, being covered by a dense layer of green algae and patches of cyanobacteria. The rose-pink colour of the T. roseopersicina blooms is due to the carotenoid spirilloxanthin. Spirilloxanthin may function as an accessory light-harvesting pigment under low-light conditions, and as a photoprotective pigment under high-light conditions. To determine whether spirilloxanthin serves a photoprotective function, photosynthetic pigments were isolated from cells exposed to high-light intensities and low-light intensities, by solvent extraction, and pigment concentrations were measured using spectrophotometry. There was no significant difference in spirilloxanthin concentration between cells exposed to high-light intensities or low-light intensities. This evidence suggests that photoprotection is not the major role of spirilloxanthin within T. roseopersicina. To determine if spirilloxanthin was acting in accessory light-harvesting, photosynthesis was indirectly measured using a pulse amplitude modulation fluorimeter. Photons absorbed by spirilloxanthin were approximately 85 percent as effective in supporting photosynthesis, as the photons absorbed by the main light­harvesting molecule, bacteriochlorophyll a. Therefore, the carotenoids within T. roseopersicina function mainly as accessory light-harvesting molecules.

38 Plant Canada 2003

Plant Canada - Contributed Poster Presentations

89 The metabolism of asparagine and aspartate in leaves of Spartina alternijlora ADONGO, L., JOSEPHSON, K. & IRELAND, R.J. Department of Biology and Biochemistry, Mount Allison University, Sackvi/le, N.B., E4L 1 G7 Perennial plants typically store nutrient reserves in underground storage structures, such as rhizomes, which become very metabolically active in spring and fall, when they are preparing to export or receive organic transport compounds. The intertidal zone of salt marshes of Eastern North America is often dominated by the facultative halophyte, S. alterniflora, which has an extensive system of roots and rhizomes. These tissues have high concentrations of free amino acids in the spring and fall, with much lower levels during the summer. Glutamine and asparagine constitute over half of the amino acid pool during spring and fall. The data suggest that following storage over the winter, amino acids are translocated up from the roots and rhizomes in the spring, then in the fall are translocated down from the senescing leaves. Asparaginase activity was detected in leaves throughout the growing season, as was aspartate aminotransferase. The latter was present as five isoforms, separable by ion­exchange chromatography, which showed different patterns of activity throughout the season.

90 Response of gamma-hydroxybutyrate dehydrogenase product and transcript levels to abiotic stress ALLAN, W.L. & #SHELP, B.J. Department of Plant Agriculture, Bovey Bldg., University of Guelph, Guelph, ON, NJG 2Wl In plants, gamma-aminobutyric acid, a non-protein amino acid, accumulates rapidly in response to a variety of abiotic stresses. Gamma-aminobutyric acid is then converted to succinic semialdehyde, which can be catabolized via two paths: one involving the production of succinate via succinic semialdehyde dehydrogenase, and the other involving the production of gamma-hydroxybutyrate via gamma-hydroxybutyrate dehydrogenase (GHBDH). We recently identified an Arabidopsis GHBDH eDNA and developed a LC/MS method for the determination of gamma-hydroxybutyrate levels in crude plant extracts. In this study, we demonstrated that gamma-hydroxybutyrate levels are increased in leaves of Arabidopsis and tobacco, as well as in soybean sprouts, after treatment with low oxygen. This was not accompanied by increased levels of GHBDH transcript. Similar experiments are underway using nitrogen, salt, drought, heat and cold stresses to investigate the universality of this response.

91 The intracellular sorting of plant peroxisomal membrane proteins differ in plant, yeast and mammalian cells ANDERSON, E.M. & MULLEN, R.T. Department of Botany, University of Guelph, Guelph, ON, NJG 2Wl, eanderOJ@uoguelph.ca Peroxisomes are single membrane-bound organelles that are found in virtually all eukaryotic organisms. Previous studies of peroxisome biogenesis revealed that the targeting signals responsible for sorting newly-synthesized soluble proteins to the peroxisomal matrix (interior) are highly conserved among evolutionarily diverse organisms. In contrast, there is limited information available on the targeting signals responsible for sorting peroxisomal membrane proteins (PMPs). While it is generally accepted that nascent PMPs can insert into the peroxisomal boundary membrane either directly from the cytosol or indirectly via the endoplasmic reticulum (ER), a consensus has not been reached whether the import machinery and targeting signals are evolutionarily conserved. To address this issue, two plant integral PMPs, Arabidopsis 22-kDa PMP (PMP22) and cottonseed ascorbate peroxidase (APX), previously shown to utilize the direct and indirect sorting pathways, respectively, were expressed in yeast and mammalian cultured cells, and their subcellular localization(s) assessed using immunofluorescence microscopy. Results indicate that both PMP22 and APX preferentially sort to mitochondria in yeast, but to peroxisomes in mammalian cells. Interestingly, sorting of APX via the ER was not observed in either organism.

ABSI'RACTS 39

Overall, these and other data presented indicate that the molecular mechanisms responsible for sorting PMPs to the peroxisome are not entirely conserved among plants, yeast and mammals.

92 Use of cpDNA sequences for studying the native and introduced taxa of the Poa pratensis complex (Kentucky bluegrass) ARCHAMBAULT, ANNIE & GILLESPIE, LYNN Canadian Museum of Nature, CP 3443 StnD, Ottawa, Ont Kl P 6P4 The Poa pratensis complex (Kentucky bluegrass) is taxonomically difficult and characterized by high polyploidy, aneuploidy, hybridization, and few useful morphological characters. Previous restriction site data (an important indel and site variation) from the chloroplast DNA region previously known as rbcl-ORF106 separated North American taxa into two groups, an indigenous arctic/alpine complex comprising P. pratensis subspp. alpigena and colpodea, and a widespread non-arctic low elevation complex comprising taxa of European origin, such as subspecies pratensis, and cultivars. These markers show promise for recognizing native P. pratensis in North America; for example, many floras do not distinguish native alpine from introduced taxa. Sequence data show that a deletion of approximately 180bp in the cpDNA rbcL-psal region (which overlaps the rbcL-ORF106 region) characterizes the arctic/alpine P. pratensis subsp. alpigena. In addition, the rbcL-psal region possesses a small region of high variability, which will be useful in studies of taxonomically difficult complexes in Poa. The aims of the present study are to determine by sequencing the cpDNA rbcL-psal region the molecular basis of the restriction site characters, to confirm the relationships between the native and introduced North American taxa, and to provide diagnostic tools to differentiate them. The relationship between European and North American lineages of the P. pratensis complex is also explored.

93 Haplotype diversity patterns in autogamous Packera paucijlora BAIN, JOHN F. & GOLDEN, JOANNE L. Dept. of Biological Sciences, University of Lethbridge, Lethbridge Alberta, Canada. T 1 K 3M 4 Packera paucijlora, is one of two wide ranging autogamous species in a genus where most species are both allogamous and prone to hybridization. Its distribution is centred in the northern Rocky mountains but it also occurs at high elevations in California and in the Gulf of St. Lawrence region of eastern Canada. Chloroplast DNA haplotype variation was examined in populations from northwestern North America and California. Haplotype diversity values within populations were generally low, especially compared to other Packera species. Most populations were monomorphic and most, but not all, populations contained haplotypes that are similar to each other and to other coastal and northern Packera populations from different species. California populations contain haplotypes not found in the northern populations. The lack of hybridization resulting from the autogamous breeding system is thought to have contributed to the reduced levels of haplotype diversity present in this species when compared with other widespread Packera species like P. cana. The high level of interpopulational variation is thought to be the result of a combination of drift and possibly some limited ancient hybridization.

94 A quantitative comparison of homeotic flowers in Philodendron (Araceae) BARABE, D.1

, LACROIX D. 2 & JEUNE B. 3

1 Institut de recherche en biologie vegetale, Jardin Botanique de Montreal, Montreal, Canada, H IX 2B2. 1 Departement of Biology, University of Prince Edward Island, Charlottetown, PEl, Canada, CIA 4P3. 3 Laboratoire de cytologie et morphogenese vegetate. Universite Pierre et Marie Curie, France. In Philodendron, pistillate flowers are initiated on the lower portion of the inflorescence and staminate flowers are initiated on the distal portion. A transition zone consisting of sterile male flowers and atypical bisexual flowers is

40 Plant Canada 2003

present between the male and female floral zones. The portion of the atypical bisexual flower facing the male zone forms stamens, and the portion facing the female zone develops into an incomplete gynoecium. The atypical bisexual flowers of Philodendron are believed to be a case of homeosis where carpels are replaced by sterile stamens on the same whorl. In P. me/inonii, P. pedatum P. squamiferum, and P. so/imoesense, there is a significant relationship between the number of carpels and the number of staminodes involved in the homeotic transformation in atypical bisexual flowers. On the other hand, such a correlation does not exist in P. fragrantissimum and P. insigne. In general, there is a one to one organ replacement in homeotic flowers in both P. pedatum and P. squamiferum. Whereas, in P. so/imoesense, an average of2.56 staminodes replace one carpel. The average number of different types of floral appendages on an atypical bisexual flower and the number of organs involved in a homeotic transformation appear to be two independent phenomena.

95 Regulation of seed germination and dormancy by putative components of the gibberellin signal transduction pathway HASSEL, GEORGE W. 1

, BEWLEY, J. DEREK1, MULLEN, ROBERT T. 1 & ZIELINSKA,

ELZBIETA2

1Dept. Botany, Univ. Guelph, Guelph, ON, NJG 2Wl; 2Dept. Genetics and Plant Breeding, Univ. Technology and Agriculture, Bydgoszcz, Poland To investigate how gibberellin (GA) signaling regulates tomato seed germination, a DELLA gene homologous to GAIIRGA (LeGAl) was isolated and examined. LeGAl exists as a single copy gene and may be the only DELLA gene in tomato. Its transcripts increase markedly following imbibition and are expressed in the embryo, micropylar and lateral endosperm. Decreases in both transcripts occur only after germination, suggesting transcriptional down­regulation of LeGAl is not a prerequisite for germination to be completed. Paradoxically, LeGAl transcription appears to be induced by GAin all seed tissues of the GA biosynthetic mutant of tomato gib-1 prior to germination. Embryos from gib-1 tomato seeds germinate in the absence of GA when removed from their surrounding tissues. This suggests that GA and the components of the GA signal transduction pathway are not required for radicle extension, i.e. the completion of germination per se, but rather are necessary for the alleviation of coat-imposed dormancy. Soybean seeds do not exhibit coat-enhanced dormancy, and their germination is not inhibited by PAC, a GA biosynthesis inhibitor. Transcription of two genes encoding DELLA proteins isolated from soybean are not induced in the radicle until after germination. These data suggest GA is not required for germination of either tomato and soybean seeds.

96 Aquaporin gene expression in roots of Pisum sativum BEAUDETTE, PHILIP1 & EMERY, NEIL 1

Trent University The expression ofaquaporins (AQPs) in the roots of pea (Pisum sativum) was examined. Primers were designed to amplify both a control gene as well as an AQP gene from pea DNA. The first primers to be designed were based primarily on nucleotide sequences of plant species other than pea. Only one of these primers annealed successfully during PCR to produce a product that could be viewed in an agarose gel. This was for the actin gene in tomato. However it was only amplified in tomato, not pea. A second set of primers included primers for a control gene (GAPDH) and an AQP (PIP2) in pea. Using PCR both worked to amplify the desired genes in pea. The AQP and GAPDH PCR products were sequenced and found to be 77.2% and 61.6% homologous to the nucleotide sequences from which they were designed. RNA has also been isolated from pea roots. Reverse transcription PCR (RT-PCR) was used to amplify the GAPDH gene. RT-PCR is now being used to amplify AQP. Diurnal variation in water uptake and transpiration rate will be related to AQP gene expression.

ABSTRACTS 41

97 Biochemical adaptation to soil moisture in a Rocky Mountain wildflower BLACKMAN, B.K. & RUVINSKY, J.R. Department of Biology, Stanford University, Stanford, CA 94114 and Rocky Mountain Biological Laboratory, Crested Butte, CO 81224 Functional studies in evolutionary genetics are required to distinguish between competing hypotheses regarding which evolutionary processes generate patterns of genetic variation. Such investigations foster mechanistic insight into the consequences of allelic variation for organismal fitness in the field. Here, we present evidence that natural selection by water stress maintains an allozyme polymorphism in 6-phosphogluconate dehydrogenase (6PGD2

)

alleles in lpomopsis aggregata. Observations that favor an adaptive explanation include: I) reproducibility of a correlation between the 3 allele (6PGD2-3) and soil moisture in two years, 2) presence of the correlation in a set of geographically isolated populations and in local subpopulations subject to heavy gene flow, and 3) discovery of two isolated high-frequency sites. We also demonstrate in situ an allele-specific effect in the response of plant performance to different soil moistures. For only those genotypes carrying 6PGD-3, plant performance--as measured by plant size--significantly correlates with soil moisture, with carriers performing better in wet sites, and worse in dry sites, relative to non-carriers. The strong selection observed, as indicated by population divergence despite gene flow and measurability of allelic impacts on performance, demonstrates that this is a promising system for the study genotype-phenotype-environment interactions and their role in evolutionary process.

98 Pseudomonas disease progression in NAHG and SID 2-2 Arabidopsis: The side effects of catechol BLOCK, A.K. & KLEE, H.J. University of Florida, 1301 Fifield Hall, POB 110690, Gainesville FL 32611 The accumulation of salicylic acid (SA) occurs in Arahidopsis thaliana in response to infections with the virulent bacterial pathogen Pseudomonas syringae pv tomato DC3000 (Pst). Plants that lack the ability to accumulate SA are more susceptible to infection by Pst, showing more severe disease symptoms and higher levels of bacterial growth. Two mutants that cannot accumulate SA are those carrying the NahG trans gene, salicyilate hydroxylase, which converts SA to catechol and sid2-2 a deletion mutant in isochorismate synthase, which is involved in the synthesis of SA. We examined the effects of the removal of SA on other hormones believed to be involved in disease progression. The production of ethylene, which occurs after SA accumulation, behaves in an opposite manner in the two mutants. Its production is increased in sid2-2, while it is decreased in NahG. This effect may be due to the presence of catechol induced hydrogen peroxide.

99 The Compositae volumes of the Flora of North America project BROUILLET, LUC, BARKLEY, THEODORE M. & STROTHER, JOHN L. Institut de recherche en biologie vegetale, Universite de Montreal, Montreal, Qc; Botanical Research Institute of Texas, Fort Worth, Texas, U.S.A.; University Herbarium, University of California -Berkeley, Calif, U.S.A. The Flora ofNorth America project has now published 6 of its 30-volume series, including Ferns and Gymnosperms, Magnoliids, and the Monocots except Grasses; two more are forthcoming in 2003, and the rhythm of publication should be 2 or more per year afterwards. The family Asteraceae is the largest in North America, with about 410 genera and 2450 species in 13 tribes, and will constitute 3 volumes of the Flora (19 to 21). The Compositae Editorial Center located at the Botanical Research Institute of Texas (BRIT) is actively editing manuscripts that now (April) comprise about 2/3 of the genera and species. As much as possible, generic treatments are written by specialists and will reflect the new thinking in Asteraceae systematics that has emerged over the past 20 years, notably with the advent of phylogenies based on molecular data. Thus, many nomenclatural changes, new delimitations of taxa and distributional data will be found in the Flora. The Compositae treatments of

42 Plant Caruukz 2003

the FNANM connect these new understandings to the many groups of consumers of botanical information. Simultaneous publication of the 3 Compositae volumes is expected in late 2004 or early 2005.

100 Global antibodies for quantitation of core biochemical complexes in natural samples BROWN, CHRISTOPHER, M. 1

, CAMPBELL, DOUGLAS, A. 1•2•

1 Department of Biology, University of New Brunswick, Fredericton, NB; 2 Department of Biology, Mount Allison University, Sackville, NB Many of the key processes shared by photoautotrophs, including light capture, conversion of excitation energy to electron gradients, carbon fixation and nitrogen assimilation, are catalyzed by abundant protein complexes which dominate the proteomes of the members of photoautotrophic communities. Certain subunits within these complexes are well conserved over wide ranges of taxa, from plants to cyanobacteria, and to varying extents among anoxygenic photosynthetic bacteria. While the core biochemical complexes from a range of photoautotrophs have been well characterized, studies of composition and biochemical properties are usually performed under near ideal culture conditions rarely encountered in nature. Under changing or suboptimal conditions, as well as across taxa, there are wide variations in the allocation patterns and stoichiometric ratios of biochemical complexes. We are developing global antibodies as tools for quantitation of members of key protein families in photoautotrophic organisms and communities. We use careful target design and rigorous characterization to generate standard antibodies intended to recognize all members of a protein family with uniform specificity, regardless of the species of origin. This property makes them particularly useful for studies of samples from complex field populations or uncharacterized species. Combined with robust extraction protocols, a set of global antibodies directed toward a suite of proteins forms the foundation of a powerful approach to studies of acclimation, metabolic optimization and resource allocation in natural samples. ·

101 Photosynthetic light response in three insectivorous plant species: Sarracenia leucophylla, Drosera rotundifolia, and Drosera capensis BRUZZESE, B.M., FREDEEN, A.L. & #MASSICOTTE, H.B. Ecosystem Science & Management, University of Northern British Columbia, Prince George, B.C. V2N 4Z9 Photosynthetic properties for insectivorous plants have not been well characterized. Thus, we investigated the photosynthetic light response in three insectivorous plants, Sarracenia leucophylla Rafm. ('pitcher-plant'; s.e. United States), Drosera rotundifolia L. (sundew; circumpolar, incl. British Columbia), and Drosera capensis L. (sundew; Cape Peninsula, Africa) in order to further our understanding of the range in photosynthetic properties among this diverse group. We used a LI6200 with a l/4-L chamber in conjunction with a QB6200 LED light source to characterize the photosynthetic light response in leaves of six greenhouse-grown plants of each species. Photosynthesis saturated with respect to light at between 100 and 200 Jlmol m·2 s·• PAR in all species. Liyht saturated photosynthesis ranged from 1.32 to 2.22 Jlmol m·2 s·• on a leaf area basis; 19.21-40.29 nmol g· s-1 on a dry mass basis, with 'native' Drosera rotundifolia having the highest rates in both cases. Dark respiration was relatively high in comparison to photosynthesis, ranging from - 1.07 (D. capensis) to -3.32 (D. rotundifolia) J..Lmol m-

2 s-1

• Photosynthetic light compensation points scaled with light saturated photosynthesis. These results suggest that S. leucophylla, D. rotundifolia, and D. capensis achieve maximum photosynthesis at low light intensities and photosynthesize at a low rate relative to non-insectivorous plants.

ABSTRACTS 43

102 Photosynthetic physiology of the cyanobacterium Synechococcus PCC 7942 grown under varying temperature and inorganic carbon states BURNS, R.A. 1

'2

, MACKENZIE, T.D.B. 1•2 & CAMPBELL, D.A. 1

'2

1 Department of Biology, Mount Allison University, Sackville, NB; 2 Department of Biology, University of New Brunswick, Fredericton, NB Cyan bacteria have remarkable capacity to re-allocate protein and pigment resources in the face of environment factors that influence their metabolism, such as inorganic carbon limitation, temperature stress, or light limitation. We characterized photosynthetic physiology and contents of major protein complexes associated with key metabolic processes for cell cultures of the freshwater cyanobacterium Synechococcus PCC 7942, grown at 25° C, 30° C, and 35° C, under both inorganic carbon limited and replete growth conditions. Preliminary results indicate that culture growth rates, presented as doubling time (in hours), showed marked depression between cells grown at 25°C when compared to those grown at either 30°C or 35°C. Differences in growth rates between the 30°C and 35°C grown cells were found to be significant but not as dramatic. Availability of inorganic carbon also had a significant effect on doubling time within each temperature group. Cells grown under COz replete conditions had faster growth rates when compared with the carbon limited treatments. The phycocyanin to chlorophyll ratio remained fairly stable within each treatment group but was significantly higher in carbon replete cells than in carbon limited ones. Further analysis will be presented with respect to relative photosynthetic quantum yields, photosynthetic electron transport and quantitation of levels of protein complexes associated with key metabolic processes. Understanding the range of acclimation responses in cyanobacteria will help explain ecosystem responses to changing environmental conditions.

103 Contrasting epiphytic macrolichen biodiversity and biomass of young (age class 5) and old growth (age class 8 and 9) Western Red Cedar/Western Hemlock forests of east-central British Columbia CAMPBELL, JOCELYN & #FREDEEN, ARTHUR L. Ecosystem Science and Management, University of Northern British Columbia, 3333 University Way, Prince George, B.C., V2N 4Z9. campbelj@unbc.ca &fredeena@unbc.ca Orographic precipitation on the windward slopes of the rocky Mountains has resulted in a globally unique inland rainforest. Disturbance events within may occur at intervals of more than l 000 years, resulting in stands that are much older than the oldest trees within them, a condition referred to as "antique". Arboreal macrolichens, assumed to be restricted to the Pacific coast, are now known to occur in these forests. We compared the diversity of macrolichens across three age classes and throughout the vertical canopy. Results indicate that the lower canopy of old-growth forests have the greatest diversity and abundance of epiphytic macro lichens and that most cyanolichens characteristic of antique stands are absent from younger forests. Management of biodiversity associated with old­growth is impeded by the absence of a reliable indicator of antiquity. We therefore investigated the use of an easily-identifiable macro lichen species as an indicator of stand age. Lobaria pulmonaria was present in a diverse range of habitats and its biomass was found to be positively correlated with old-growth conditions and macro lichen diversity. It is hoped that a greater understanding of lichen ecology across age classes, coupled with the existence of this operationally feasible indicator ofbiodiversity, will promote sustainable stewardship of this rare and species-rich forest type.

44 P/ant Canada 2003

I

104 RSO (sym16), a pea nodulation and cytokinin over-producing mutant CARR, BRET1

, EMERY, NEIL2, FERGUSON, BREIT3 & #GUINEL FREDERIQUE1

1 Department of Biology, Wilfrid Laurier University, Waterloo, Ontario, N2L 3C5; 2 Department of Biology, Trent University, Peterborough, Ontario, K9J 7B8; 3 School of Plant Sciences, University a/Tasmania, Hobart, Tasmania, 7001 R50 is a nodulation mutant exhibiting decreased height, raised veins, thickened internodes and roots, decreased root number, and few nodules. Nodulation is restored by treatment with ethylene inhibitors. These features and those of etiolated R50 indicate that the mutant could be ethylene hyper-sensitive, but some of R50 phenotypic traits point towards abnormal levels of cytokinins (CK). An histochemical study of R50 indicated that, compared to the wild-type (WT), R50 root vasculature was more complex and its embryos were heavier and characterized by thicker and larger root meristems. In addition, R50 leaves were thicker (caused by additional schlerenchyma in the veins and increased mesophyll cell size in the blades) but had less surface area than the WT. Complex root vasculature, larger meristems and thicker leaves have been linked to abnormal CK levels. R50 CKs were analyzed by liquid chromatography- tandem mass spectrometry. By 9 days after planting (dap), R50 had twice as much total CK as the WT and, by I 7 dap, the difference between R50 and WT had widened to 4-fold. We conclude that R50 is a CK over-producer, which makes it the first nodulation mutant to be described as such.

105 Improved expression and biochemical characterization of a recombinant Arabidopsis GABA transaminase CLARK, S.M., VAN CAUWENBERGHE, O.R. & #SHELP, B.J. Department of Plant Agriculture, Bovey Bldg., University of Guelph, Guelph, ON, NJG 2Wl Gamma-aminobutyrate (GABA) accumulates in response to various biotic and abiotic stresses. It is catabolized to succinic semialdehyde via GABA transaminase, which can use either pyruvate or 2-oxoglutarate as an amino acceptor, producing alanine and glutamate, respectively. Recently, we cloned an Arabidopsis GABA-T eDNA, which encodes a 504-amino acid polypeptide possessing a putative mitochondrial signal sequence. Functional expression of the eDNA in Escherichia coli revealed that the recombinant protein uses pyruvate, but not 2-oxoglutarate. Unfortunately, the level of expression was low, and the protein very unstable, even in the presence of standard protective agents. In this study, the level of expression was dramatically improved by the use of Escherichia coli Rossetta cells co-expressing the GroES/GroEL chaperone complex. Determination of the specificity of the purified recombinant protein for various amino acid donors and acceptors is underway.

106 Variation in leaf biomass dynamics among Ontario wetland plants occurring along a north-south gradient *COULAS, J.A. & RYSER, P. Department of Biology, Laurentian University, Sudbury, ON, P3E 2C6 The amount of living and dead plant material present at a given location is limited by the external factors (stress and disturbing agents) acting within the environment. Shaped by local factors, successful plants develop the necessary coping strategies for resource capture and utilization. It has been established that growth and decomposition parameters are lower in plants adapted to severe environments, yet there is also an indication that this generalized pattern differs for some herbaceous plant forms. In contrast to evergreen species, leaf life spans in herbaceous plants may decrease with a decreasing growing season length while the relative growth rates increase. It is unclear which external factors are most influential in dictating herbaceous growth form strategies. The main goal of this project is to assess how inherent traits (i.e. tissue production and turnover rates), known to influence ecosystem processes, vary among individual ecotypes and species present in wetlands occurring along a north­south gradient in Ontario. While grown within our outdoor experimental garden in Sudbury, we look to uncover

ABSTRACTS 45

both intra- and interspecific differences in various leaf traits of wetland sedges and grasses adapted to different environments of contrasting growing season length and severity in climatic conditions.

107 Proteome-level differences between two varieties of Pisum sativum L. exhibiting differences in emergence DALE, P.L. 1

, KAY, N.N.V. 1 & BLADE, S.2

1 Dept of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB. T6G 2P5; 2Alberta Agriculture, Food and Rural Development, 17507 Fort Road, RR#6, Edmonton, AB, T5B4K3 We have investigated the differences in protein profiles between two cultivars of Pisum sativum. These varieties differ in their time of emergence after planting as well as when germinated under saline conditions. P. sativum variety Nitouche, which exhibited poor field emergence in 2002 also showed greater sensitivity to salt stress when germinated in Petri-dishes, compared with P. sativum line 356973, which had shown good emergence under field conditions. At 75 mM sodium chloride, lengths and fresh masses of shoots and radicles were significantly reduced in Nitouche compared with line 356973. One- and two-dimensional gel electrophoresis of extracted soluble seed protein from these two cultivars revealed that a relatively major protein of approximately 69 kD was absent in Nitouche but present in line 356973. MALDI-TOF analysis of this 69 kD protein band identified it as convicilin, a globulin-type storage protein that also contains significant hydrophilic sequences. Results from these studies are presented and a potential relationship between hydrophilic proteins and germination vigour is discussed.

108 Inorganic carbon uptake in two marine dinoflagellates DASON, J.S., HUERTAS, I.E. & #COLMAN, B. Department of Biology. York University, Toronto, ON. M3J I P3 Inorganic carbon uptake was investigated in two marine dinoflagellates, Amphidinium carterae and Heterocapsa oceanica. Mass spectrometric and potentiometric assays indicated that both species lacked external carbonic anhydrase (CA). The presence of internal CA was demonstrated by a potentiometric assay. The capacity for bicarbonate transport was investigated by comparing the calculated rate of spontaneous C~ formation with the rate of photosynthesis at an external HC03- concentration of 100 _M. Neither species appeared to have the capacity for direct bicarbonate uptake. Monitoring C02 and 0 2 fluxes in both species by mass spectrometry demonstrated a rapid uptake of C02 on illumination, to concentrations below the C02 equilibrium concentration, indicating an effective, selective uptake of C02• Growth of both species on high C02 caused a suppression of growth, a decrease in external pH from 8 to 7 and loss of photosynthetic activity. Cells exposed to high C~ for 6 hours had lower affinities for C02 and higher C02 compensation concentrations than air-grown cells. A decrease in external pH caused a parallel decrease in internal pH and this inability to maintain a constant internal pH is probably the reason for the suppression of growth and the loss of photosynthetic capacity in high COrgrown cells.

109 Is response of floral nectar production to elevated C02 levels predictable from floral nectary structure? DAVIS,A.R. Department of Biology, University of Saskatchewan, Saskatoon, SK, S7N 5E2 Nectar is a carbohydrate-rich food source sought by many flower visitors. Studies of the influence of elevated C02 levels on floral nectar production to date have involved ten dicotyledonous species from eight families. Eight species have floral nectaries lacking secretory trichomes; instead these glands are multicellular outgrowths bearing modified stomata on their surfaces. Despite their similar nectary structure, when plants were subjected to C02 enrichment ranging from 600-1000 ppm, one species produced significantly more nectar sugar per flower, two

46 Plant Canada 2003

produced less, and five did not differ from controls (255-380 ppm). Owing to the constancy of nectar-solute concentration between treatments in these studies, alterations in nectar volume secreted led to these variations in nectar sugar production per flower. Nectary structure alone is not an accurate predictor of floral-nectar production response to C02 enrichment.

110 Ecophysiological responses to burial in woody species of Lake Huron sand dunes *DECH, J.P. & MAUN, M.A. Department of Biology, University of Western Ontario, London, ON, Canada Burial in sand is a recurrent abiotic stress that imposes a strong selective force upon plants in sand dune ecosystems. Woody species show variable tolerance to burial; however, its impact on these plants remains unclear. We studied the responses of saplings of four woody species of the sand dunes of Lake Huron to burial treatments of 0, 10, 25, 50 and 75% of their height in a field experiment initiated in October 2001 at the Pinery Provincial Park. During the 2002 growing season we measured carbon dioxide exchange rates (CER) and stomatal resistance for each species monthly from June to August. All measurements were made on clear days between 10:00 and 15:00 with a portable infrared gas analyzer (LI-6200, Li-Cor, Lincoln, Nebraska, USA). There were two general responses to burial. The tolerant species Populus balsamifera and Salix cordata, had 100% survival in all burial treatments, and showed increased CER and decreased stomatal resistance with increasing burial depth. The intolerant species, Juniperus virginiana and Thuja occidentalis had high mortality in deeper burial treatments (e.g. 75%), and showed decreased CER and increased stomatal resistance with deeper burial. These results suggest that burial stress is related to its effect on plant water status and the concomitant effect on photosynthesis.

111 Characterizing the genetic basis of quantitative trait differences between ecotypes of A vena barbata using recombinant inbred lines. *GARDNER, K.M. & LATTA, R.G. Dalhousie University, Halifax, Nova Scotia, B3H 4H6 To investigate the genetic basis of differences between naturally occurring ecotypes we have constructed a population of 188 recombinant inbred lines (RIL) from two genotypes of Avena barbata that show strong association with moist and dry habitats. An initial survey of all 188 lines was conducted in the greenhouse, alongside their parental ecotypes, for a suite of early and later growth traits such as germination time, tiller number, flowering time vegetative vs. reproductive biomass and spikelet number. Broad sense heritability estimates for all traits were high (>.50) among the RILs and significant genetic correlations among traits were detected. The RILs were subsequently genotyped with 150 AFLP markers found to be polymorphic between the parental ecotypes. Linkage analysis reveals the markers group into several small linkage blocks that span 360 centimorgans of the A. barbata genome. Single marker quantitative trait locus (QTL) mapping analysis has identified marker loci that show strong association with at least one trait and several markers showing association with multiple traits. Preliminary interval mapping has revealed one position where QTL for flowering, spikelet number and vegetative biomass co-localize and another where QTL for spikelet and tiller number co-localize.

112 Patterns of storage protein and triacylglycerol accumulation during loblolly pine somatic embryo maturation GIFFORD, D.J., BROWNFIELD, D.L., STONE, S.L. & TODD, C.D. Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada, T6G 2E9 Loblolly pine (Pinus taeda L.) somatic embryos synthesized and accumulated a set of seed storage proteins that were similar to their zygotic counterparts. SDS-PAGE analysis identified three major proteins; a 60 KDa glutelin­like protein, comprised of 37.5 and 22.5 peptides linked by a disulphide bridge, a 47 KDa globulin, and a 15 KDa

ABSTRACTS 47

globulin. Accumulation of the 60 KDa and 47 KDa storage proteins was evident during early maturation; five weeks after transfer from liquid culture to maturation media; the 15 KDa globulin was not evident until mid­maturation, nine weeks after transfer. Quantitatively, total embryo protein accumulation began two weeks after transfer, and maximum levels were attained six weeks later during mid maturation. On a fresh weight basis anatomically mature somatic embryos contained approximately 44% of the total insoluble proteins and approximately 257% of the total soluble proteins of their zygotic counterparts. Temporally, total triacylglycerol (TAG) accumulation mirrored protein accumulation. On a fresh weight basis, anatomically mature somatic embryos contained approximately 27% of the total TAG content of their zygotic counterparts.

113 Magnetic resonance imaging of developing Brassica seeds and siliques GILMER, S. 1

, GALKA, M.2, BONHAM SMITH, P.C. 1

, ABRAMS S.R. 1•2

1 Department of Biology, University of Saskatchewan, Saskatoon, SK, S7N 5£2; 2 Plant Biotechnology Institute, NRC, Saskatoon, SK, S7N OW9 The failure of canola (Brassica napus) seed to degrade chlorophyll after sublethal freezing is called the green seed problem. The presence of chlorophyll in the resulting oil requires added clean up steps during processing and means a lower price for producers. Although we know that the failure to degreen is associated with precocious desiccation, it and even normal degreening processes are poorly understood. Nuclear magnetic resonance (NMR) using a Broker A vance 360 MHZ wide bore machine equipped for microimaging is a non-invasive method of visualizing the distribution of water to a pixel resolution of 40 m. In an attempt to better understand the movement of water and deposition of oil during seed development, magnetic resonance images (MRI) were generated illustrating water and oil distribution in developing intact siliques, seeds and funiculae of Brassica napus cv Westar during normal desiccation and accelerated desiccation caused by mild frost.

114 Cytffrom the psychrophillic Antarctic alga Chlamydomonas subcaudata is functional in mesophillic alga Chlamydomonas reinhardtii GUDYNAITE-SAVITCH, L.,1 GRETES, M.,1 SAVITCH, L.V} SIMMONDS, J.,2

KOHALMI, S.E.,1 & #HUNER, N.P.A. 1

1 Department of Biology, University of Western Ontario, London, Ontario, N6A 5B7, Canada; 2ECORC, Agriculture and Agri-Food Canada, Ottawa, Ontario, KIA OC6, Canada The psychrophillic alga C.subcaudata, isolated from an Antarctic lake, is a natural state transition mutant. Cytochromef(cW) from C.subcaudata has a 7kD lower apparent molecular mass than cyif(4lkD) from C.reinhardtii. The sequence analysis of the petA gene from C.subcaudata, expression of mature cyiffrom both Chlamydomonas species in E.coli, and analysis of the thermostability of heme binding to these proteins indicated that the difference in the apparent molecular mass of cyiffrom C.subcaudata compared to C.reinhardtii is likely due to a conformational change which may induce functional differences in photosynthetic electron transport as well as the ability to undergo state transitions. We transformed a petA deletion mutant of C.reinhardtii with cyif gene from C.subcaudata. The transformants show the same apparent molecular mass of the cyifas in C.subcaudata, are able to grow photoautotrophically and can undergo state transitions. In vivo measurements of oxidation/reduction ofP700 showed that transformants have reduced capacity for intersystem electron transport and faster P700 re-reduction. In addition, trans formants show lower photosynthetic capacity and no changes in photosynthetic efficiency. Observed differences in the photosynthetic electron transport oftransformants might be the result of lower abundance and/or lower activity of cyiffrom C.subcaudata in petA trans formants.

48 Plant Canada 2003

115 Tolerance limits of Atlantic coastal plain plants: What prevents colonization on a reservoir? HAZEL, S., REEKIE, E. HILL, N. & NEWELL, R. Department of Biology, Acadia University, Wolfville, NS, B4P 2R6, Department of Biology, Mount Saint Vincent University, Halifax, NS, BJM 216 Atlantic Coastal Plain species include some considered rare in Canada, often found only in South-western Nova Scotia. Frequently found on lakeshores, these species appear sensitive to hydrological patterns which are drastically altered by damming. Various key points during the hydrological cycle are affected by damming, including a later drawdown of water (shortening the growing season), a later refilling of basins (leaving plants vulnerable to frost damage) and a larger within year variation in water levels. The purpose of this study was to examine tolerance limits of rare coastal plain species and similar species found growing with them, and also on reservoirs. Using elevated boxes planted at two times, the effect of growing season length and soil moisture content on seven species (4 coastal plain- Hydrocotyle umbellata, Sabatia kennedyana, Coreopsis rosea and Panicum longifolium and 3 associated species- Eleocharis acicularis, Viola lanceolata and Panicum spretum) was examined. Analysis of niche breadth for soil moisture showed differences between species although no pattern of coastal plain and associated species was observed. No group wide differences in coastal plain and associated species were found regarding soil moisture niche bread suggesting that this is not preventing colonization on reservoir shores.

116 Biomass allocation patterns and production of anti-herbivory defense chemicals in purple loosestrife (Lythrum salicaria) over a range of grazing pressure *HISCOTI, J. & NOSKO, P. Department of Biology, Nipissing University, North Bay, ON, P 1 B 8L7 Two exotic leaf-eating beetles (Galeruce/la ca/mariensis and G. pusilla) have been released in North American wetlands to biologically control the invasive plant, purple loosestrife. The purpose of our study was to examine the impact of herbivory on resource allocation to growth, reproduction and anti-herbivore defense in purple loosestrife. Studies were conducted at three locations in Ontario; Peterborough, North Bay and Burlington, where Galerucella beetles were released in 1993, 1995 and 1997, respectively. At each study location, growth, biomass allocation and the production of phenolic compounds were compared for purple loosestrife plants from beetle release sites and non-release reference sites. On release sites, herbivory resulted in a mean loss of 16.7% of leaf surface area compared to 7.2% at reference sites. Loosestrife plants allocated a greater proportion of above-ground biomass to leaves (45.7%) and a lower proportion to inflorescences (2.0 %) at release sites than at reference sites (leaves= 3 7.1 %, inflorescences = 12.1 %), suggesting the possibility of a compensatory growth response to herbivory. Greater allocation to leaves appeared to be at the expense of inflorescence biomass and the production of phenolic compounds. Leaf concentrations of phenolics were higher for plants on reference sites compared to those at release sites, suggesting that loosestrife employs a constitutive chemical defense strategy. Plants at beetle release sites had significantly lower phenolic levels than at reference sites, supporting compensatory growth of leaves occurring at the expense of defense. Purple loosestrife is though to be sufficiently unpalatable that native phytophagous insects are unlikely to control the spread of this plant. Reduced production of leaf phenolic compounds due to high feeding levels by introduced Galerucella beetles could make purple loosestrife more palatable to native herbivores.

117 Effects of plant material storage protocols on antioxidant enzyme activities HODGES, D. MARK1

, LESTER, GENE E.2, MEYER, R.L.2 & MUNRO, KATHLEEN D. 1

1Atlantic Food and Horticulture Research Centre, Agriculture and Agri-Food Canada, Kentvil/e, Nova Scotia, B4N JJ5, Canada; 2 Kika de Ia Garza Subtropical Agricultural Research Center, United States Department of Agriculture-Agricultural Research Services, Weslaco, Texas 78596, USA

ABSTRACTS 49

Many laboratories store plant materials prior to enzymic analyses, as opposed to the immediate assessment of activities from fresh tissue. To the best of our knowledge, no comprehensive published study exists which compares activities of antioxidant enzymes from fresh plant materials with those from plant tissues stored under commonly reported protocols. To this end, activities of the antioxidant enzymes ascorbate peroxidase, catalase, dehydroascorbate reductase, glutathione reductase, guaiacol peroxidase, monodehydroascorbate reductase, and superoxide dismutase were immediately determined in fresh honeydew melon (Cucumis melo L.) fruit and spinach (Spinacia oleracea L.) leaves following harvest. Samples from the same pooled tissues used in the fresh analyses were either placed directly in a -80ooC freezer, thoroughly frozen in liquid nitrogen and then placed in a -8()<x)C freezer, freeze-dried, or used to create acetone precipitates. Samples were analysed immediately following freezing, freeze-drying, or acetone precipitation treatments to examine effects of sample processing on enzyme activities. To study effects of storage time on enzymic activities, frozen, freeze-dried, and acetone precipitated samples were stored at -80ooC for 14, 28, and 56 days before analysing for specific activities. The effects of processing and storage on activities of these antioxidant enzymes will be discussed.

118 Screening for photoacclimation deficient mutants in Chlamydomonas reinhardtii using an Arylsulfatase reporter gene *HUMBY, P.L. & DURNFORD, D.G. Dept. of Biology, University of New Brunswick. Bag Service #45111, Fredericton, NB. E3B 6E1 Photoacclimatory mechanisms are needed to optimize photosynthetic function in a variable environment. Photosynthetic complexes are composed of proteins encoded on both the nuclear and plastid genomes; thus, any photoacclimatory changes require a coordinated effort between these two organelles. The nuclear encoded light­harvesting complex ofPhotosystem II (LHCII encoded by Lhcbl) is transcriptionally regulated and must assemble with chloroplast-encoded components, making it a good system to investigate chloroplast-to-nucleus signal transduction pathways. Lhcb I regulation can be monitored in Chlamydomonas reinhardtii transformed with an arlylsulfatase reporter gene construct (Lhcb 1 : :Ars ). Transcription of this reporter gene is light regulated, such that a shift from low-light to high-light decreases expression, while a shift to very low light increases expression. By using insertional mutagenesis we are able to screen for individuals that do not respond to light shifts in this predictable manner and; therefore, have defects in this form of transcriptional regulation. Characterizing photoacclimatory mutants will enable us to identify factors involved in signal transduction pathways between the chloroplast and nucleus.

119 Characterization of the molecular targeting signalS that direct tail-anchored cytochrome b5 isoforms to either mitochondria or endoplasmic reticulum *HWANG, Y.T., DYER, J.M. 1

, & MULLEN, R.T. Department of Botany, University of Guelph, Guelph, ON, N1G 2W1; 1USDA-ARS-SRRC, New Orleans, LA 70124, USA Cytochrome bs (Cbs) is a tail-anchored {N0u1-C;n) integral membrane protein that plays a central role in various electron transfer reactions in eukaryotic cells. Four Cbs isoforms identified from the tung tree (A/eurites fordiz) (termed Cbs A, B, C and D) were shown to possess a high degree of homology except in their C-terminal transmembrane domains (TMD) and tail regions. Indirect immunofluorescence microscopic analyses of each Cbs isoform in transformed tobacco cells revealed that while isoforms A, B and C localized to the endoplasmic reticulum (ER), isoform D localized to mitochondria. To characterize the molecular targeting signals responsible for the differential localization of Cbs isoforms, site-specific mutations were introduced into the C-terminal TMDs and/or tails of CbsA and CbsD. Results indicate that the CbsA ER-targeting signal consists of a -R-x-Y /F-xn motif located in the C-terminal tail. In contrast, the CbsD mitochondrial targeting signal consists of both a dibasic motif (-RIK-KIR-xn) located in the C-terminal tail and a -P-X6-S-x3-S/G-xrYIF- motif located in the immediately­adjacent TMD; only when both motifs are intact does CbsD target with high fidelity to mitochondria. Overall, these

50 Plant Canada 2003

results suggest that different C-terminal targeting signals mediate the differential localization ofCb5 proteins in plant cells.

120 Enzymes of glutamine and glutamate metabolism in leaves of Spartina alterniflora IRELAND, R.J., KELLY, H., & MCINTYRE, L. Department of Biology and Biochemistry, Mount Allison University, Sackville, N.B., E4L 1 G7 Spartina alterniflora is a perennial grass that often dominates the intertidal zone of Eastern North American salt marshes. Its roots, rhizomes, and leaves have high concentrations of free amino acids in spring and fall, with lower levels during the summer. Glutamine and asparagine comprise over half of the amino acid pool, serving as the major nitrogenous transport compounds. In roots, glutamine synthetase (GS) and NADH-glutamate synthase showed similar seasonal patterns, peaking in early spring and fall. GS levels were much higher than glutamate synthase, presumably providing the glutamine for export or synthesis of asparagine. In rhizomes, GS peaked later in the spring, but NADH-glutamate synthase showed a less pronounced seasonal pattern. Two GS isoforms were separated from leaf extracts: the activity of both decreased throughout the growing season, but the activity of one form decreased more quickly and was absent by the end of the summer. Immunolocalization revealed a complex pattern of changes in cellular distribution of GS I and GS2 during the season.

121 Fitness consequences of hybridization in Avena barbata: Dominance, epistasis and GXE interactions *JOHANSEN, A.D. & LATTA, R.G. Department of Biology, Dalhousie University, Halifax, Nova Scotia, B3H 411 The fitness consequences of hybridization will be influenced by dominance, epistasis and GXE interactions. These are expected to differ between early and late generation hybrids, and among segregating genotypes. We examined the long term and short term consequences of hybridization between ecotypes of Avena barbata using 6 F2 families and 25 F6 families. We also examined genotype X environment interactions in a subset of 12 of the F6 families. Fitness (spikelet number), flowering time and biomass were measured in both experiments. No evidence for hybrid vigour or hybrid breakdown was found in the F2 generation. Hybrid breakdown for all three traits was found in the F6 generation, with only 2 families outperforming the parents in spikelet number and flowering time. Estimates of dominance, epistasis and additivity indicate that dominance may be counteracted by the break-up of co-adapted gene complexes in early generation hybrids. Preliminary analysis of 12 F6 families in 8 different environments shows genotype X environment interactions do occur. Although two families do exhibit high fitness in all environments the rank order of fitness of genotypes does change across environments.

122 Spatial modeling of plant's genes dispersal and western Alps postglacial recolonisation: a new methodology for the case of Biscutella laevigata (Brassicaceae) JOOST, STEPHANE & PARISOD, CHRISTIAN Laboratory of Geographical Information Systems, Swiss Federal Institute ofTechnology, Lausanne, Switzerland & Institute of Ecology, Geobotanics Laboratory, University of Lausanne, Switzerland Spatiality influences genetic diversity. Population genetics could gain accuracy by coupling them together with GIS potential habitat and dispersion modeling. Identification of anisotrope gene flux in the landscape seems of primary importance to better explain the genetic diversity in natural populations. Biscute//a /aevigata L. (Brassicaceae) is a Mediterranean perennial herbaceous species growing in the Alps. It is supposed to have colonized the Alps before the last glacial maximum with 2n= 18 chromosomes and to have recolonized this area after the Wiirm in a doubled chromosomes form (2n=36, autotertaploid). The recolonisation would have started from ice free parts where the

ABSTRACTS 51

original population survived. The identification of migration pathways used by this species could help in explaining the mutation and in understanding the genetic implications of polyploidy in relationship with migration processes. A new GIS-based approach provides predictive habitat's maps as likelihood spaces. Transportation vectors maps (wind, gravity, hydrography) are then overlayed with these areas to make genes migration pathways appear. This approach should help population geneticists in discriminating between processes shaping genetic diversity. Habitat modeling will generates insights about the environmental factors playing a selection role by comparing them with the optimal range of the whole variables acting on species survival. Identifying migration pathways of genes will be of great interest for biodiversity management and conservation purposes, as well as for topics related to plant distribution under changing climate.

123 Tree ring increment and needle ion concentrations as indicators of coastal stress in Daniel's Harbour, Newfoundland *KEEFE, A.P. & NOSKO, P. Department of Biology, Nipissing University, North Bay, ON, P 1 B 8L7 Coastal forests of Newfoundland are subjected to considerable stress and disturbance, largely due to high wind velocities and salt spray. Winds and salt deposition are especially high during extra-tropical storms associated with Atlantic hurricanes. During such events in the New England states, salt toxicity symptoms have been reported for trees more than 70 km inland. Coastal trees are often stunted and adopt a "krummholz"-like growth form while trees at even short distances from the coast may exhibit a more "regular" growth form. The purpose of our study was to examine the impact of coastal environmental conditions on tree growth by comparing radial stem increment for balsam fir and white spruce trees at coastal and inland locations near Daniel's Harbour, Newfoundland. A greater deposition of ions associated with marine salts was suggested by significantly higher tissue (needle) levels of these ions in coastal (0 km from coast) trees compared with inland (3 km from coast) trees. Coastal trees exhibited reduced and eccentric radial growth compared to inland trees. Ring widths for the seaward side of coastal trees were narrower than on the leeward side. Tree-ring chronologies for coastal and inland white spruce correlated with precipitation received through the growing season; chronologies for balsam fir did not. Radial growth patterns for the seaward side of coastal trees did not correlate to leeward patterns while leeward patterns for coastal fir trees were strongly related to seaward and leeward patterns of inland trees. This suggests that directional stresses associated with coastal environments exert a strong influence on the growth of coastal trees and that, even over short distances, environmental gradients along coast-to-inland transects are steep.

124 Biotransformation of Hg2

+ by selected cyanobacteria KELLY, DAVID J.A., BUDD, KENNETH & LEFEBVRE, DANIEL D. Department of Biology, Queen's University, Kingston, ON K7L 3N6, Canada Biotransformation ofHg2+ by selected cyanobacteria was investigated in pH-stat cultures at environmentally relevant Hi+:chl a ratios. A novel method permitted quantitative determination of _-HgS. Direct, simultaneous determination of this pathway together with losses to the reductive Hg0 pathway was made, thereby assessing the fate ofHg2+ in real time. Upon exposure of cyanobacteria to Hg2

\ acid SnCh reducible Hg (free ions and complexes) was transformed to alkaline SnCh reducible Hg signal consistent with _-HgS and inconsistent with other biologically-reported mercury compounds. Initial biotransformation process included a rapid phase for _-HgS synthesis (K112 of minutes) and high Hg0 evolution, but the rate of the latter decreased rapidly. This is consistent with ecological literature from which Hg0 volatilization would be expected to occur from the surface-water interface for only a short time following precipitation. The synthesis of _-HgS appears to require intracellular thiols and active metabolism as interference with either favored Hgo volatilization. Therefore, cyanobacteria at the air­water interface would primarily act to sediment Hg2+ as _-HgS. This suggests that _-HgS, not chelated Hg2+, is the relevant dietary mercurial for algal grazers. In addition, direct exposure to Hg2+ may not be appropriate for methylation studies in sediments.

52 Plant Canada 2003

125 Rotary encoders for monitoring diurnal rhythms in plant stem elongation and leaf movement KRISTIE ,D.N. 1

, JEONG,H.S.L.2, BLOM T.3 & HICKLENTON, P.R.4

1 Department of Biology, Acadia University, Wolfville, Nova Scotia, Canada, B4P2R6; 2

National Alpine Agricultural Experiment Station, San 1, Hyunggae-Ri, Doam-Myun, Pyeongchang-Kun, Kangwon-Province, 232-955, Korea; 3 Department of Plant A~riculture, University of Guelph, 4890 Victoria Avenue N., Vineland Station, ON, LOR 2£0; Agriculture and Agri-Food Canada, Atlantic Food and Horticulture Research Centre, Kentvi//e, N.S., Canada, B4N 1J5 Displacement transducers (LVDTs) have been widely used in studies involving measurement of plant stem growth. While L VDTs are ideal for short term high resolution measurements of stem elongation, they are finicky to set up, and their use in long term growth studies involves complex control systems to reposition the sensor in relation to the growing plant. We have developed a simple reliable growth system for the long term measurement of stem growth, using education grade rotary sensors based on rotary encoder technology. These systems are relatively inexpensive, simple to set up, and have been used for research and classroom studies on diurnal rhythms of stem elongation and leaf movements in a variety of plants.

126 PSII Excitation pressure and Phosphorylation of Dl proteins KROL, M. 1

., BOOU-JAMES, I.S.2, MATTOO, A.K.2

, WILSON, K.E.3, MISKIEWICZ, E. 1 &

#HUNER, N.P.A. 1

1 Department of Biology, UWO, London, Ontario,N6A5B7, Canada; 2USDA-ARS Vegetable Laboratory, Beltsville, MD 20705-2350, USA; 3Department of Molecular Biology, University of Geneva, Geneva 1204, Switzerland Plants possess various mechanisms of photoprotection, such as the xanthophyll cycle, state transitions, D I turnover, and reaction centre quenching measured by thermoluminiscence {TL). State transitions and D1 turnover were compared in barley wild type (WT) and the F2 chlorina mutant grown at high or low excitation pressure using phosphothreonine antibodies and 32P labelling. The F2 chlorina barley lacks LHC II proteins, but the level of Lhcb5 (CP26) is higher in this mutant than the WT. CP26 is not phosphorylated and state transitions are not induced in the F2 mutant. D 1 protein phosphorylation in the F2 mutant grown at high excitation pressure was not detected using phosphothreonine antibody, but was detected using 32P labelling. In contrast, Dl phosphorylation was detected in the WT using both techniques. This discrepancy may result from the phosphorylation of serine instead of threonine in the D 1 of the F2 mutant. TL studies show that, PSII photochemistry is altered in F2 relative to WT when grown under high excitation pressure. We conclude that the F2 mutant exhibits altered PSII photochemistry which may reflect alternations in the D 1 protein of PSII reaction centres.

127 Settlement, growth and population differentiation of Codium fragile in Maritime Canada #KUSAKINA, J. & DADSWELL, M.J. Department of Biology, Acadia University, Wolfville, NS, B4P 2R6 The green alga Codiumfragi/e ssp. tomentosoides has become a worldwide "weed" alga during the 20th century. The appearance of this pest in Nova Scotia in 1989 has been a dramatic change in marine algal flora in Maritime Canada. Spreading rapidly along Atlantic shores the alga is now found in NS, NB and PEL Recent studies on Codium raise the possibility of two subspecies invading eastern Canada. A part of my research will concentrate on settlement and early growth of Codium, and will be conducted at an aquaculture site in Mahone Bay using ropes suspended between 0-10 m as an artificial substrate. The substrate will be retrieved and examined after 2 months

ABSTRACT'S 53

in the water for time and depth of Codium settlement. The growth rate of Codium will be calculated from its length and dry weight. Adult Codium will be examined for the type of reproduction (whether it is sexual or asexual), reproductive activity, and viability of reproductive cells under controlled conditions in the laboratory. Investigation of a two possible invasive Codium subspecies presence in eastern Canada will be done using RAPD technique. Samples from Western Canada, the USA, and possibly Europe will be compared to determine where species are derived from.

128 Genetic diversity and spatial distribution of aquatic hyphomycete species Articulospora tetracladia populations from different streams LAITUNG, B., MILLOT, S. & CHAUVET, E. Laboratoire de Ia Dynamique de Ia Biodiversite, 29 rue Jeanne Marvig, 31 055 Toulouse, France Articu/ospora tetracladia (ascomycete teleomorph: Hymenoscyphus tetracladius) reproduces by both asexual and sexual means. However, as in most aquatic hyphomycete species, asexual reproduction by numerous conidia predominates in aquatic environments. Genetic variation of aquatic hyphomycete populations from different streams is related to the dissemination of spores. It is presumed that water dispersal is the prevailing mode of mitotic spore dissemination, but the distances travelled are not well known, and dispersal by animals may also occur. Furthermore, airborne dispersal of sexual spores cannot be excluded over long distances. Therefore, the study focussed on (i) the extent of genetic differentiation among isolates of A. tetracladia from different streams, (ii) the range of potential spore dispersal and (iii) the relationships between distribution of A. tetracladia populations and environmental characteristics of the stream (e.g. riparian vegetation diversity). Single spores were isolated from foam samples collected from ten woodland headwater streams over a geographical range in the Montagne Noire region of France. Genetic variation of A. tetracladia populations was assessed by RAPD fingerprinting. Preliminary results applied to 150 isolates suggest that the genetic diversity of these fungal populations is controlled by their localization.

129 Changes in vegetation communities in the salt marshes of Kouchibouguac National Park of Canada •LEBLANC, S. 1

, MAZEROLLE, D.M. 1, VASSEUR, L. 1 & TREMBLAY, E?

1 Universite de Moncton, Pav. P.A. Landry, Moncton, NB E1A 3E9; 2 Kouchibouguac National Park of Canada, N.B. North Field Unit, 186 Route 117, NB E4X 2P 1 Salt marshes in the eastern coast of New Brunswick are important habitats but are gradually threatened by human development and activities. In 1977, seven marshes in the park were surveyed to characterize the type of vegetation. In 2002, they were revisited to examine the plant composition changes in these communities. The same approach was used in both surveys and was based on the Whittaker sampling method. The results show that the four zones characterized in the first survey were still present in 2002, each dominated by one of the following species: Juncus gerardii, Juncus balticus, Spartina alterniflora, and Spartina patens. The size of the superior part of the marshes was slightly smaller in 2002 than in 1977, with species suggesting a more advanced stage of succession. Species of forest ecosystems such as Trientalis borealis can be found in some of the marshes in 2002.Richness has declined from 70 species in 1977 to 56 in 2002. The 2002 data disagree with the 1977 conclusion that the adjacent vegetation does not influence the type of vegetation on site. With climate change and more frequent changes of the coast, these marshes could become endangered as well as some of the species that they host.

54 Plant Caruula 2003

130 Light and low concentrations of inorganic carbon control the expression of transcripts related to the C02-concentrating mechanism in Synechocystis sp. strain PCC6803 McGINN, P.J. 1

, PRICE, G.D & BADGER, M.R. Molecular Plant Physiology Group, Research School of Biological Sciences, Australian National University, Canberra, A. C. T, Australia. 1 Present Address: Department of Biology and Coastal Wetlands Institute, Mount Allison University, Sackville, NB, Canada The abundance of key transcripts coding for inducible inorganic carbon (Ci) transporters and expressed in support of the C02-concentrating mechanism (CCM) in Synechocystis PCC6803 were quantified by real-time RT-PCR under conditions of varying Ci and light. When cells were bubbled with C02-free air for 30 minutes the abundances of cmpA, sbtA and ndhF3 transcripts increased by 3.3 x 104 %,4.3 x 103 % and 3.8 x 102 %, respectively, in illuminated cells and by 55%, 20% and 60%, respectively, in darkened cells (no statistical significance), relative to illuminated cells bubbled with high concentrations of C02, where the CCM is typically repressed (high-Ci cells). The initial [Ci] in both illuminated and darkened cell suspensions was < 150 mM just prior to the onset of COr free aeration. The requirement for light and low [Ci] for CCM-related gene expression was explored further by incubating cells in a cuvette attached to a membrane-inlet mass spectrometer to enable the measurement of photosynthetic gas exchange rates, [Ci] and [02] simultaneously with the quantitative analysis of the 3 key transcripts. The abundance of transcripts tended to increase in the presence of increasing irradiance and low [Ci] and under conditions of constant irradiance and decreasing [Ci], relative to high Ci cells. The expression of the cmpA and ndhF3 transcripts was completely inhibited by I 0 mM 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), but it had no effect on the expression of sbtA transcript. The regulation of CCM induction in this strain is discussed in relation to its similarity to redox control mechanisms.

131 Differential regulation of the alternative oxidase (Aoxl) gene of Chlamydomonas reinhardtii in response to oxidative stress and nitrogen source *MOLEN, TERESA & MAXWELL, DENIS Department of Biology, University of New Brunswick, Fredericton, NB, E3B 5A3 Besides the cytochrome pathway of mitochondrial electron transport, plants possess a second, alternative pathway of respiration which is comprised of a single protein, the alternative oxidase (AOX). While AOX is a mitochondrial protein, it is encoded by a family of nuclear genes, one of which (Aoxl) is strongly induced by oxidative stress in higher plants. The focus of this research is to investigate the regulation of AOX in the green alga Chlamydomonas reinhardtii. To study the transcriptional state of Aoxl we employed a reporter system consisting of 1074bp of the Aoxl promoter fused to the coding region of the arylsulfatase (Ars) gene. In transformed control cells, ARS expression was low but was dramatically induced when cells were shifted from a medium containing ammonium to one containing nitrate. This increase was confirmed using RNA blot analysis. However, cells treated with compounds known to cause oxidative stress (Antimycin A, H20 2) did not cause any ARS expression even though an increase in Aoxl mRNA resulted. This failure to activate the reporter indicates that the I 074bp promoter is not sufficient to drive Aoxl transcription in response to oxidation stress.

132 Establishment, regeneration niche interactions and facilitation succession among six boreal bryophytes MULLIGAN, ROISIN C. & DALE, M.R.T. Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E7 The ability of six boreal bryophytes (Sphagnum angustifo/ium, S.fuscum, S. mage//anicum, P/eurozium schreberi, Pti/ium crista-castrensis and Aulacomnium palustre) to establish from gametophytic fragments on natural burnt peat medium in peatland and botanic garden settings over two years was examined. Sphagnum fuscum did not

ABSTRACTS 55

regenerate in any treatment and its present distribution in this peatland may be the result of past facilitation by colonist bryophytes. Sphagnum magellanicum failed to grow where planted, however; its appearance in other treatments at the peatland suggests colonisation via sexual diaspores.

Sphagnum angustifo/ium regenerated with good success in all treatments and appeared via sexual or asexual diaspores in many others. Pleurozium schreberi and Pti/ium crista-castrensis grew successfully where planted. Aulacomnium palustre established with high frequency as a planted and unplanted species. Prolific growth of unplanted acrocarpous colonist and fugitive bryophytes suggests an important role for facilitation succession in post-fire bryophyte peatland communities. Between the two years of the study the unplanted, r­selected colonists increased in frequency partially at the expense of the planted K-selected species and this decline is attributed to an absence of specialisation in the latter for expansion in hostile post-fire habitats.

133 Levels of individual glucosinolates in wrapped and unwrapped postharvest cauliflower (Brassica oleracea L. var. botrytis L.) during controlled atmosphere and air storage MUNRO, KATHLEEN D., HODGES, D. MARK & FORNEY, CHARLES F. Atlantic Food and Horticultural Research Centre, Agriculture and Agri-Food Canada, Kentville, Nova Scotia, B4N JJ5, Canada Glucosinolates are a class of sulfur containing compounds found in members of the Brassica family. The glucosinolates are largely responsible for the taste and smell of cruciferous vegetables. In addition, glucosinolates can undergo hydrolysis to produce products such as isothiocyanates which evidence suggests are important anti­cancer agents. Variation in levels of glucosinolates in wrapped and unwrapped postharvest cauliflower (Brassica oleracea L. var. botrytis L.) may be related to atmospheric composition, packing method and/or storage length. Levels of individual glucosinolates were measured throughout controlled atmosphere (CA) storage regimes (humidified air or 3% C02 and 5% 0 2) in wrapped and unwrapped cauliflower heads. Samples were removed from each chamber (DO, 14, 28, 42 and 56), frozen in liquid nitrogen, lyophilized and stored at -40°C until analysis. Glucosinolates were extracted from the freeze dried tissue with methanol, desulfated and analyzed using an HPLC protocol. The effects of wrapping and CA storage on individual glucosinolate levels in cauliflower will be discussed.

134 Characterization of ~carotene hydroxylase T -DNA insertion mutants in Arabidopsis thaliana QIN, X., SCHWARTZ, S.H. & #GRAY, G.R. Department of Biochemistry, University of Saskatchewan, Saskatoon, SK, S7N 5E5 In the Arabidopsis genome, two probable ~-carotene hydroxylase genes have been identified. Heterologous

expression in E. coli indicates that gene products are able to catalyze the hydroxylation of the ~-ring and~­carotene and a-carotene. The T-DNA insertion lines SALK_Ol2481 and SALK_044659 disrupt respectively the

~OHl and ~OH2 gene. The single mutants {3ohl and {3oh2 showed no significant difference in growth or

carotenoid compositions compared to wild type. Plants homozygous for the ~OHl and ~OH2 insertion were

crossed. The Fl plants generated from this cross (~OHI {3ohl ~OH2 {3oh2) also had a normal appearance. These plants were allowed to self pollinate and the genotypes of the segregating plants was monitored by a PCR-based approach. More than 180 plants have been screened to date. The segregation ratio for the different genotypes was non-mendelian. Additional crosses are now being made to elucidate the function of the two ~-carotene hydroxylase genes during Arabidopsis development.

56 Plant Canada 2003

135 Iron bioavailability and iron uptake by the cyanobacterium Anabaena jlos-aquae PETTERSON, C.D. 1

, TREBLE, R.G.2 & WEGER, H.G. 1

1 Dept. of Biology, Univ. of Regina, Regina, SK, S4S OA2, 2 Saskatchewan Health, Provincial Laboratory, Regina, SK, S4S 5W6 Iron acquisition from various ferric chelates was studied using iron-limited cells of Anabaenajlos-aquae (Lyng.) Breb UTEX 1444, a cyanobacterial strain that produces high levels ofsiderophores under iron limitation. Various chelators of greatly varying stability constants (HEDT A, EDDHA, desferrioxamine mesylate, HBED) were assayed for the degree of iron acquisition by iron-limited cyanobacterial cells. Iron uptake rates (measured by GF AAS) varied inversely with chelator stability constant, and decreased with increasing chelator to iron ratio. No iron uptake was observed when Fe(III) was chelated with HBED, the strongest of the tested chelators. Iron-limited cells of A. jlos-aquae were able to take up iron from purified humic acid, and also from 8-hydroxyquinoline ("oxine"), a compound frequently used to preconcentrate iron in aquatic samples. These results suggest that for cyanobacteria, even tightly bound iron is biologically available, including iron bound to humic acids. However, iron bound to chelators with a stability constant greater than approximately 38 is likely to be biologically unavailable.

136 Puccinia tripsaci - a new rust fungus for Canada PUNTER, DAVID Department of Botany, University of Manitoba, Winnipeg, Manitoba, RJT 2N2, Canada Puccinia tripsaci Dietel et Holw. has been known to occur on its telial hosts, Tripsacum and Andropogon in a number of states of the central and eastern U.S. It is also reported on the aecial host, Ceanothus, from Colorado, Kansas, Nebraska and Wisconsin. P. tripsaci has recently been found in the southeastern portion of the province of Manitoba, Canada from 49' -50'30'N and 95'30' -96'20'W. In this area Ceanothus and Andropogon coexist on sandy soils together with long-established jack pine, Pinus banksiana Lamb. The discovery of this fungus in southern Manitoba represents a significant northward extension of its known range and a new occurrence for Canada. It appears to be sufficiently widespread and damaging to have some ecological impact but neither host is of any great economic importance.

137 Variable cost of reproduction in relation to resource availability REEKIE, E.G. & #A VILA-SAKAR, G. Acadia University, Wolfville, NS, Canada, B4N JJ6. According to optimal allocation theory, organisms are constrained in the amount of resources they can invest on reproduction by fitness tradeoffs with other functions (e.g. growth, defence). In plants, simple models of resource allocation predict a linear decay in vegetative biomass as the reproductive biomass increases. However, there is empirical evidence that plants that achieve low reproductive output suffer little change in their vegetative biomass. We constructed a functional equilibrium model with realistic features such as root and leaf senescence, growth of support and reproductive tissues, and independent C/N ratios of vegetative and reproductive tissues. We considered only two major resources: light and soil nitrogen. We explored the cost of reproduction at contrasting levels oflight and nitrogen availability, for reproductive tissues with either high or low C/N ratio relative to the vegetative tissue. We found that the cost of reproduction per unit of vegetative biomass increases with increasing levels of reproductive allocation (proportion of resources devoted to reproduction) at any combination of conditions excepting high levels of nitrogen availability. This curvature was more pronounced in plants with longer reproductive periods. Our model approximates empirical data better than models that yield a constant cost of reproduction.

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138 Photoacclimation in Cyanophora paradoxa: insights into the evolution of light harvesting and photoprotective strategies RISSLER, H.M. & DURNFORD, D.G. Department of Biology, University of New Brunswick, Fredericton, NB EJB 6E1 Photosynthetic organisms ranging from anoxygenic photosynthetic bacteria to higher plants employ a variety of conserved and unique mechanisms to acclimate to their environment. The acquisition of plastids and subsequent transfer of genes from the endosymbiont to host genome introduced unique challenges to the process of photoacclimation in that photosynthetic eukaryotes must coordinate the expression of separate genomes in order to effectively balance light harvesting and energy dissipation. Cyanophora paradoxa, which retains a peptidoglycan plastid envelope and phycobilisomes (PBS) remnant of its cyanobacterial progenitor, is believed to represent an early stage in the evolution of photosynthetic eukaryotes. We have characterized photoacclimation in this organism and preliminary data revealed an expected down-regulation in PBS content in response to high-light acclimation. Surprisingly, chlorophyll levels remained constant following 48 hours of high-light exposure, in contrast to trends observed in cyanobacteria. As part of the Protist EST Program, we are also generating and sequencing eDNA libraries from both low-light and high-light stressed C. paradoxa. Elucidating the regulation of high-light induced changes in gene expression and identifying novel photoprotective strategies employed by this "ancient" photosynthetic eukaryote will provide insight into the evolution of photoacclimation responses as well as the origin of nuclear-plastid genome signalling pathways.

139 Over-expression of the plastid terminal oxidase of Arabidopsis thaliana exhibits increased capacity as an electron sink *ROSSO, D.a, IVANOV, A.G.b, RODERMEL, S.b, & HUNER, N.P.A.a a Department of Biology, University of Western Ontario, London, ON, N6A 5B7; b Department of Botany, Iowa State University, Ames, Iowa 50011 Chlororespiration has been defined as a chloroplastic respiratory electron transport chain (ETC) that interacts with the photosynthetic ETC. The plastid terminal oxidase (PTOX) is linked to the chlororespiratory pathway and IMMUTANS codes for PTOX. We hypothesize that PTOX in the IMMUTANS over-expressor (IM) should exhibit increased capacity to act as a sink for photosynthetic ETC and result in decreased sensitivity to photoinhibition. Both the IM and the wild type (WT) were grown at 20EC at an irradiance of either 50 or 150 cl>mol m·2s·1

• In both the WT and IM, the chlorophyll a:b ratios increased from 2.85 to 3.20 and chlorophyll per leaf area doubled during growth at 150 compared to 50 cl>mol m"2s"1

• Imrnunoblot analysis showed that the levels ofPsaA, PsaB, Lhca, and the NDH complex remained constant on a chlorophyll basis. The extent ofP700 photooxidation in 1M was 50% greater at 150 cl>mol rn·2s-1 and 15% greater at 50 ci>mol m"2s"1 as compared to the WT. We suggest that PTOX may play a significant role as an alternative electron sink in 1M in comparison to the WT. The impact that this may have on sensitivity to photoinhibition will be discussed.

140 Purification and biochemical characterization of a recombinant plant gamma­hydroxybutyrate dehydrogenase SHELP, B.J., HOOVER, G.J. & VAN CAUWENBERGHE, O.R. Department of Plant Agriculture, Bovey Bldg., University of Guelph, Guelph, ON, N1G 2W1 In plants, gamrna-aminobutyric acid, a non-protein amino acid, accumulates rapidly in response to a variety of abiotic stresses such as hypoxia. Under normoxia, garnrna-aminobutyric acid is catabolized to succinic semialdehyde and then to succinate, with the latter reaction being catalyzed by succinic semialdehyde dehydrogenase. Complementation of a succinic semialdehyde dehydrogenase-deficient yeast mutant with an Arabidopsis eDNA library allowed the identification of a novel gene for gamrna-hydroxybutyrate dehydrogenase

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(GHBDH). The purified recombinant protein, isolated from a soluble Escherichia coli fraction, catalyzed the irreversible reduction of succinic semialdehyde to gamma-hydroxybutyrate with NADPH, but not NADH, as a co­factor. Kinetic analysis revealed positive cooperativity towards succinic semialdehyde, suggesting multiple substrate-binding sites, and activation by gamma-hydroxybutyrate, an unusual feature associated with enzymes. The physiological function of GHBDH activity in plants under hypoxia will be discussed.

141 Effects of salinity stress on pea (Pisum sativum L.) SRIVASTAVA, S. 1

, KAY, N.N.V. 1 & BLADE, S.2

1 Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, T6G2P5; 2Alberta Agriculture, Food and Rural Development, RR6, 17507 Fort Road, Edmonton, Alberta T5B 4K3 Proteomics-based discovery techniques allow the identification of proteins involved in plant responses to stress. The identified proteins may lend themselves as specific targets for crop improvement via classical breeding or biotechnology. Salinity affects 20% of the world's arable land and more than 40% of irrigated land; salinity also imposes a type of water deficit stress in plants that affects the growth and development of plants leading to a decrease in agricultural productivity. We have used proteomics-based techniques to investigate the effects of salinity stress in plants using pea (Pisum sativum L., cultivar Cutlass) as a model. Short-tenn effects of salinity stress were assessed at gennination, seedling emergence and early seedling growth in Petri dishes and long-tenn effects were investigated at whole plant-level in the greenhouse. Overall responses of peas to salinity stress (short and long-tenn) were assessed using biochemical and physical parameters. Proteome-level changes that accompany salinity-induced changes in biochemical and physical parameters were investigated using electrophoresis. Identities of selected proteins whose levels showed significant changes in response to the imposed stress were · determined using MALDI-TOF and MALDI-Q-TOF Mass Spectrometry. The identities of some proteins will be presented and their potential role(s) in plant responses to salinity stress discussed.

142 The importance of frost boils for the recruitment of arctic-alpine plants in the Mealy Mountains, Labrador SUTTON, JOLENE1

, #HERMANUTZ, LUISE 1 & JACOBS, JOHN2

Departments of1Biology and 2Geography, Memorial University, St. John's, NL. AlB 3X9 In environments with closed vegetation safe sites for seedling recruitment are limited. The objective of this study was to determine if gaps caused by frost boils represent appropriate substrate for recruitment and persistence of arctic-alpine plants. To conduct this study, frost boil distribution and associated vegetation were surveyed in the Mealy Mountains, Labrador. To determine if frost boils are important for recruitment, comparisons of seedling densities in frost boils and closed vegetation were made, and persistence of Diapensia lapponica within frost boils was examined. Total seedling density was greater within frost boils than adjacent closed vegetation. Diapensia lapponica numbers increased in some resurveyed frost boils, indicating that persistence was likely. Using dowels inserted in the ground, substrate upheaval was shown to be significantly greater within frost boils than within closed vegetation. Within frost boils, upheaval was highest near the center and decreased outward, resulting in the observed zonation of vegetation. Higher soil temperatures within frost boils may enhance gennination and help account for higher seedling densities. Smaller seed banks, combined with higher seedling densities, confirmed that frost boils are more favorable sites for gennination. However, if global climate change alters arctic-alpine substrate dynamics, adverse consequences to seedling recruitment can be expected.

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143 Regulation of a-Dioxygenase expression in salt and pathogen-challenged roots *TIRAJOH, A., AUNG, T. & PLANT, A.L. Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A JS6 Alpha-dioxygenase ( a-DOX) catalyzes the oxygenation of fatty acids to yield a newly identified group of oxylipins and is up-regulated in leaves following pathogen challenge, herbivory, and treatment with jasmonic acid, salicylic acid and chemicals that elicit reactive oxygen species. In tomato roots a-DO X was identified as a salt-regulated gene and its expression is also up-regulated by pathogen challenge and mechanical wounding. In roots a-DOX expression is abscisic acid (ABA)-responsive; however, in the ABA-deficient mutantjlacca (jlc) and in roots exposed to fluridone (FLU) both salt and pathogen treatments up-regulate a-DOX expression. Furthemore, in FLU-treated roots exposure to a subsequent salt or pathogen treatment results in enhanced a-DO X expression relative to that in salt- or pathogen-treated roots in the absence of FLU. Given the role of ABA in suppressing ethylene accumulation in osmotically-stressed roots this suggested a role for ethylene in regulating a-DO X expression. To establish whether this was the case, plants were exposed to the ethylene generating agent ethephon or an inhibitor of ethylene action, silver thiosulphate (STS). In roots, ethephon dramatically enhanced a-DO X expression. The expression of a-DO X in STS-treated roots was unaffected but reduced when combined with a salt treatment. In Arabidopsis leaves it is thought a-DOX protects tissues against oxidative stress accompanying pathogen challenge. We are currently assessing a-DOX expression in Arabidopsis roots and using available knockouts for Arabidopsis a-DOX to explore a-DOX function in roots.

144 Physiological causes and ecological consequences of interspecific variation in biomass turnover among wetland plants *VERNESCU, C.I. & RYSER, P. Department of Biology, Laurentian University, Sudbury, ON, P3E 2C6 Plant species use the same major resources of light, water, C02 and mineral nutrients for growth and survival. Ecological differences among vascular land plant species arise from the different ways of acquiring and making use of these resources rather than from the use of different resources. Fast growing species, characteristic of highly productive sites, maximize acquisition of resources whereas slow-growing species of unproductive sites maximize their conservation. The slow growth of the latter is due to the trade-off between growth and persistence; producing 'cheap' tissue having a high turnover rate allows for fast growth, while slow growth is a result of dense tissue, required for longevity and nutrient conservation. Most existing knowledge is based on studies either comparing evergreen with deciduous species, or investigating species of strongly human-influenced agricultural grasslands. In the present study, interspecific variation in turnover characteristics will be assessed among species characteristic of Northern Ontario wetlands. Emphasis of the investigations lies on the novel aspect of phenological variation in plant traits associated with turnover, such as tissue density, specific leaf area, leafEfe span and leaf phenology. Variation in the content of non-structural carbohydrates will also be assessed, an aspect so far neglected in turnover studies.

145 Suberin lamellae forming on the short cells of a dimorphic exodermis after endomycorrhizal hyphae penetration WELCH, CATHERINE & #PETERSON, CAROL A. Department of Biology, University of Waterloo, Waterloo, ON, N2L 3Gl Roots of leek (Allium porrum L.) have a dimorphic exodermis composed of long and short cells. Both types of cells have Casparian bands; the long cells also have suberin lamellae, but the short cells tend not to have this second modification. Both endomycorrhizal and pathogenic fungi enter such roots through the short cells but cannot

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penetrate the long cells because of their suberin lamellae. It has been suggested that the growth of an endomycorrhizal fungal hypha through a short cell may induce it to form a suberin lamellae, thus preventing a pathogenic fungus from using this point of entry to infect the root. To test this idea, roots of leek seedlings were either exposed to a mycorrhizal fungus or not. Short cells Jacking lamellae were identified in situ in root segments by treating them with disodium fluorescein. Short cells without lamellae became fluorescent as the fluorescein could contact their plasma membranes and concentrate in their nuclei and cytoplasms. Short cells (and long cells) with suberin lamellae remained nonfluorescent. Subsequent clearing and staining for fungal hyphae with chlorazol black E verified that roots exposed to mycorrhizae had been colonized. Preliminary results indicated that roots that had been colonized by an endomycorrhizal fungus had significantly fewer short cells without suberin lamellae than nonmycorrhizal roots. Work is continuing with the aim of achieving a direct comparison of fungal penetration and lamella formation in short cells.

146 Triploidy, apomixis and latitudinal genetic variation in the Slim-Leaf Onion (Allium amplectens) in western North America *WHEELER, E.J. & ALLEN, G.A. Department of Biology, University of Victoria, PO Box 3020 STN CSC, Victoria, BC V8W 3N5. Allium amplectens occurs in dry open habitats from southern B.C. to southern California. Diploids, triploids and tetraploids (2n = 14, 21 and 28 respectively) are known. Although the chromosomal races are similar in floral and vegetative traits, triploid plants produce asynaptic pollen dyads, in contrast to diploids and tetraploids which produce a tetrad of normal pollen grains. Northern (B.C.) populations of this species are exclusively triploid and appear to reproduce mainly by vegetative offsets, with few individuals recruiting from seed. In contrast, more southerly populations are commonly diploid or tetraploid and can reproduce abundantly by seed. Northern populations have relatively low levels of genetic variation (based on isozyme and preliminary AFLP evidence) and appear to possess a subset of the alleles found in more southern populations. Preliminary pollination experiments on plants from B.C. populations suggest that the triploids may be pseudogamous, producing embryos by apomixis but requiring fertilization to produce endosperm. Current investigations include (i) embryo sac development in plants of the three different ploidy levels and (ii) the geographic distribution of chromosome numbers and AFLP patterns.

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Plant Speciation Symposium - Oral Presentations

(Note: This list includes selected abstracts from Plant Canada associated with speciation. These titles are found at the end of the alphabetical list of symposium contributions.)

147 Historical biogeography of circumarctic plants ABBOTT, RlCHARD J. School of Biology, University of St Andrews, St Andrews, Fife KY 16 9TH, Scotland, UK The present-day arctic flora comprises approximately 1500 species and is of relatively recent origin. Throughout most of the Tertiary (65-2 Ma), forests grew at high latitudes in the Arctic and tundra did not appear until the late Pliocene. Initially tundra was distributed discontinuously, but a circumarctic belt was present by 3 Ma. Little is known about the origins of arctic plants or the migration routes they followed during the initial colonization of the Arctic. In addition, uncertainty remains over where circumarctic plants survived Pleistocene glaciations. A phylogenetic analysis of chloroplast DNA variation in the Purple saxifrage (Saxiftaga oppositifolia) indicates that this plant first occurred in the Arctic in western Beringia before it migrated in east and west directions to obtain a circumpolar distribution. Moreover, the geographical distribution of cpDNA variation in the species supports the hypothesis that refugia were located in Beringia during Pleistocene glaciations as well as in other periglacial areas outside the main ice sheets. The results of recent phytogeographic studies on two other circumarctic species (Saxiftaga cernua and Vaccinium uliginosum) have extended further our understanding of the historical biogeography of circumarctic plants.

148 Hybridization, pol('ploidy and speciation in Spartina Schreb. (Poaceae) AINOUCHE, M.L. & BAUMEL, A.2

'University ofRennes1-UMR CNRS Ecobio 6553, Bat. 14. Campus Scientifique de Beaulieu 35 042 Rennes Cedex. France; 2 Institut Mediterram!en d 'Ecologie et de Pa!eoecologie. Bat. Villemin. Domaine du Petit Arbois, Avenue Philibert, BP 80 CEREGE 13 545 Aix en Provence, France Hybridization and polyploidy are well illustrated in genus Spartina where at least three cases of recent interspecific hybridization have been well documented, with well-known evolutionary and ecological consequences. Spartina species are perennial tetraploid, hexaploid or dodecaploid plants colonizing salt marshes. Most Spartinas are native to the New World and only four species originate from Western Europe. Three of them are of hybrid origin, being the result of the introduction of the Eastern American Spartina alternijlora (2n = 62) into Western Europe at the end of the 19th century, and its subsequent hybridization with the indigeneous Spartina maritima (2n = 60). In Southern England, hybridization resulted in a sterile perennial hybrid, S. x townsendii that gave rise to a vigorous fertile allopolyploid Spartina anglica (2n = 120, 122, 124). This young and successful species bas rapidly colonized British salt marshes and is now introduced on several continents. In southwest France, hybridization between S. alterniflora and S. maritima led to the formation of another hybrid species, S. x neyrautii. The mode of formation of these taxa, as well as the genomic divergence of the parental species and their phylogenetic relationships will be discussed in the light of various lines of molecular evidence.

149 Verne Grant and Louisiana Irises: Is there anything new under the sun? ARNOLD, MICHAEL L., BOUCK, AMY C., & CORNMAN, R. SCOTT Department of Genetics, University of Georgia, Athens, GA 30602, USA The impact of Verne Grant's 1981 edition of Plant Speciation reverberates as strongly today as it did 22 years ago. His insights into the field of plant evolutionary biology continue to inform current and future research programs.

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For example, Grant's work pointed the way for those who have argued that the consequences of natural hybridization are of primary importance in the evolution of many plant and animal species complexes. It is thus now widely accepted that numerous, important outcomes are afforded by crosses between divergent lineages. In the present paper we highlight some of the concepts that appear in Grant's seminal work. We address these in the context of their application by Grant to a plant species complex that we have studied for 15 years, the Louisiana Irises. We consider Grant's inferences in light of new data and our own conclusions. In the main, we find ourselves supporting Grant's ( 1981) conceptual framework.

150 Selection in an Ipomopsis hybrid zone: Implications for ecological speciation CAMPBELL, D.R. Department of Ecology and Evolutionary Biology, University of California, Irvine CA 92697 USA The fitness of hybrids relative to parental species plays an important role in models of speciation. In flowering plants, ecological speciation may be driven by divergent selection of floral traits by pollinators, at the expense of intermediate phenotypes. An alternative model involves physiological adaptation of plants to distinct environmental conditions, which may be accompanied by reproductive isolation due to environment-dependent selection against hybrids. We are examining the lifetime fitness ofF! and second generation hybrids, using Grant's classic example of lpomopsis aggregata and I. tenuituba as a model system. Pollination studies reveal some disruptive selection on a floral trait (corolla width), but there is considerable geographical variation in the strength of this pollinator preference and hybrids do not generally suffer lower pollination. Reciprocal transplants show that survival of hybrids depends on both genotype and environment. Combining survival and reproduction, certain types of hybrids are more fit than one or both parents in parts of the hybrid zone. Ecophysiological studies show that hybrids can be more water use efficient than either parent, perhaps contributing to success in dry hybrid habitats. The dynamics of this hybrid zone involve a mixture of selection mediated by pollinators and other sources.

151 Evolution in spatially structured populations CHURCH, S. Indiana University, USA Recent models of speciation have incorporated population structure and migration into the class Dobzjansky­Muller model of speciation. The results have shown that speciation may occur despite incomplete isolation among demes. It has also been shown that, in some cases, low levels of migration may actually enhance the rate of speciation among demes. In this paper, we expand upon these models to incorporate increasingly realistic types of population structure and gene flow into these models of speciation.

152 Reticulate evolution in diploid and polyploid perennial soybeans (Glycine subg. Glycine) DOYLE, J.J. 1

, DOYLE, J.L. 1, RAUSCHER, J.T. 1 & BROWN, A.H.D. 2

1 Department of Plant Biology, Cornell University, Ithaca, NY, USA, and 2 Centre for Plant Biodiversity Research, CSIRO, Canberra, ACT, Australia Glycine subgenus Glycine is a group of about 20 perennial species, mostly native to Australia, that is the sister group to the subgenus that includes the annual cultivated soybean (G. max). Phylogenetic incongruence between chloroplast DNA (cpDNA) and nuclear genes suggests hybridization and introgression both between distantly related diploid species and between diploid taxa that have diverged much more recently. Reticulation also has led to allopolyploidy in the subgenus, involving at least eight different genome combinations. Allopolyploid taxa appear to be very recent, perhaps having evolved since the arrival of humans in Australia around 40,000 years ago.

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Some genome combinations have arisen at least six different times, and in some but not all cases origins have been bidirectional, involving different maternal progenitors. Reticulate evolution at the polyploid level can have a profound impact on the evolution of gene families, as it has in the case of copy number and expression in the 18S-26S nuclear ribosomal gene family of sub g. Glycine.

153 Geographic Cohesion, Parallel Adaptive Radiations, and Consequent Floral Evolution in Ca/ochortus (Calochortaceae) GIVNISH, THOMAS J. & PATTERSON, THOMAS B. Department of Botany, University of Wisconsin, Madison WI 53 706 Calochortus has undergone extensive diversification in floral morphology, habitat, serpentine tolerance, and chromosome number, and many species are restricted to small geographic areas. A cpDNA phylogeny identifies seven major, geographically cohesive clades, centered in the Bay Area, Pacific Northwest, Coast Ranges-Sierra Nevada, San Diego area, Southwest California, Great Basin, and Central Mexico. Geographic cohe-sion also operates at lower taxonomic levels, with sister species often being peripatric. The genus arose in California, in the Coast Ranges or Sierra Nevada, which were them-selves uplifted during the last 3-5 million years. Three of the four major floral syndromes evolved at least twice, in association with particular kinds of habitats. Serpentine tolerance evolved at least seven times. A base chromosome number ofx = 9 is ancestral; divergence among clades in chromosome number helps create reproductive isolation in most cases where different clades overlap. We argue that limited dispersal ability led to narrow endemism of individual taxa, the geographic cohesion of clades, and parallel adaptive radiations in different areas. We propose that floral syndromes have under-gone consequent radiation, reflecting adaptation to local pollinators and physical conditions as species invaded different habitats, rather than divergent selection to partition pollinators or attain reproductive isolation.

154 Speciation in plants: how much has been learned since 1950? GOTTLIEB, L.D. University of California, Davis My talk will review how speciation in plants has been studied since 1950, when Ledyard Stebbins published his important book, "Variation and Evolution in Plants." Between 1950 and 1980, the leading American students of plant species were Verne Grant, Jens Clausen and Harlan Lewis. They emphasized different aspects of species biology and, not surprisingly, came to different, though overlapping, conclusions about how speciation occurs in plants. I will discuss their important results and show how their ideas have stimulated recent research, particularly that making use of the attitudes and techniques of molecular genetics and molecular systematics. In addition, I will suggest several topics having to do with species divergence that now seem appropriate for focused analysis.

155 Fern speciation: Different mechanisms meet different challenges and opportunities HAUFLER, CHRIS Kansas University, USA Long considered to be poster children for allopolyploid ("secondary" sensu Grant) speciation, recent studies have demonstrated that homosporous fern lineages have also experienced a wide range of mechanisms leading to "primary" species. Outcrossing mechanisms and simple breeding systems offerns predisposes them to form hybrids, thereby launching the cascade of events resulting in allopolyploid species. Because such species are hosts to genomic diversity, they are primed for diversification via reciprocal gene silencing. At the diploid level, mechanisms promoting fern diversification have been described but are largely untested. By combining DNA sequencing and isozyme electrophoretic techniques, an improved perspective on primary speciation in ferns has been obtained. Comparing speciation pathways in a temperate triad of sister species to those in a tropical quartet

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indicated that classic allopatric models followed by reinforcement are likely among the temperate species whereas diversification by adaptation to ecologically distinct habitats prevails among the tropical ones. Temperate sister species tend to be molecularly quite distinct from each other but remain morphologically very similar. The tropical sister species, on the other hand, are distinct morphologically but nearly identical molecularly. Such contrasts indicate that ferns, as other plants, follow a variety of pathways when initiating new evolutionary lineages.

156 Genetics of reproductive isolation between Aquilegia formosa and A. pubescens HODGES, SCOTT A. Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA 9 3106 USA Verne Grant used Aquilegiaformosa and A. pubescens as his first specific example of how species may be reproductively isolated due to floral differences. In order to understand the extremely rapid radiation of species in this genus, we have been investigating the genetic basis of shifts in floral morphology and their consequences to reproductive isolation. Floral differences between these two species have a strong impact on which animals visit their flowers and the efficiency of pollen transport. In order to estimate the genetic architecture of these floral differences we constructed a genetic linkage map using 330 F2 individuals and both microsatellite and AFLP markers. Quantitative trait locus (QTL) mapping has revealed that some floral characters (e.g., floral spur color and flower orientation) are controlled by few QTL of large effect while others (e.g., nectar spur length and petal blade length) are controlled by many QTL each of smaller effect. In addition, our analysis has revealed that many segments of the genome had distorted segregation ratios of which nearly all favored alleles derived from A. formosa. Furthermore, some segments were distorted only through the male parent and others only through the female parent. This detailed genetic analysis has therefore revealed new characters that are likely important in causing reproductive isolation between these species and provides the basis for future investigations into their genetic basis.

157 Evolutionary dynamics of diploid-polyploid contact zone: insights into polyploid speciation HUSBAND, B.C. & SABARA, H. Department of Botany, University of Guelph, Guelph, ON, NJG 2Wl Polyploidy is viewed as an important and rapid mechanism of speciation in plants, yet our understanding of the process by which polyploids arise and establish is poor. In theory, new polyploids will experience a strong frequency-dependent mating disadvantage, raising the question of what ecological and genetic factors are responsible for their establishment. Here I explore these questions using research from the diploid-tetraploid contact zone in Chamerion angustifolium (Onagraceae). We find that indeed tetraploids experience a frequency­dependent mating disadvantage, which is reinforced, rather than counterbalanced by the moderate viability of tetraploids. Two factors that may account for the success oftetraploids are explored: assortative mating and polyploid formation. We find that polyploids are produced at a surprisingly high rate, but this alone cannot compensate for the minority cytotype disadvantage. Assortative mating between ploidies is very strong and includes several prezygotic reproductive barriers. Furthermore, reproductive isolation is assymetrical, favouring the establishment oftetraploids within mixed populations. These results suggest that population processes leading to polyploid establishment are often restrictive and, depending on rates of assortative mating and polyploid formation, polyploid speciation may be a slower and more complex process than once thought.

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158 Historical inferences from the self-incompatibility locus IGIC, BORIS & KOHN, JOSHUA R. University of California, San Diego, USA Ancestral polymorphism preserved at the self-incompatibility locus provides information over a much longer time scale than neutral polymorphism. This enables us to draw inferences about historical occurrences far older than extant species. In this paper we outline the ways in which studies of the S-locus can provide useful insights into patterns of speciation. First, we review the evidence concerning the prevalence of founder events in speciation. A dramatic population size reduction is expected to leave a pattern of reduced sequence diversity at the S-locus that is diagnosable for tens of millions of years following the relaxation of the bottleneck. Generally, the lack of evidence for such bottlenecks preserved at the S-locus indicates that this mode of speciation is rare. Second, uninterrupted polymorphism at the S-locus provides a novel opportunity to reconstruct with certainty ancestral states of an important mating system character, the presence or absence of incompatibility. We demonstrate this approach using a phylogenetic analysis to find that transitions from self-incompatibility to self-compatibility are common and irreversible in the Solanaceae. Currently, self-compatible taxa outnumber self-incompatible taxa. Therefore, self-incompatibility is either slated for extinction or the presence of incompatibility increases the net diversification rate, maintaining a mixture of self-incompatible and self-compatible species in equilibrium. We briefly outline how phylogenetic approaches can be used to determine the effect of incompatibility on diversification. Self-incompatibility, present in many plant lineages, provides a unique opportunity to test the effects of a mating system character on diversification rate.

159 Gene flow and adaptive population divergence LATTA, ROBERT G. Department of Biology, Dalhousie University, Halifax, Nova Scotia, B3H 4Jl, Canada Contrasts between quantitative traits and molecular markers suggest that quantitative traits typically diverge in response to local selection pressures more than do individual genes. However, it is debated to what extent migration affects adaptive divergence. I will review theory showing that under diversifying selection on quantitative traits, covariances develop among allele frequencies at additive loci underlying quantitative traits. These covariances contribute a substantial fraction of the among population trait variance permitting considerable trait divergence with limited divergence of allele frequencies at the underlying loci. Thus adaptive trait divergence can be accomplished in the face of substantial gene flow. Simulations suggest that gene flow influences within population variation to a greater extent than it affects divergence. Thus in some instances, gene flow may enhance, rather than constrain. the ability to adapt to local or novel environments. However, the contribution of covariances among loci to the divergence of traits depends upon there being multiple loci underlying quantitative trait variation. Empirical work in our lab is directed to mapping genes underlying ecotypic differences in Avena barbata in California and towards studying the fitness consequences of hybridization between the ecotypes.

160 The cytoplasmic factor in plant speciation LEVIN, DONALD A. Section of Integrative Biology, University of Texas, Austin, Texas 78713 The role of nucleocytoplasmic interactions in the genesis of post-zygotic isolation has been given little attention by plant evolutionists. I present evidence from reciprocal crosses, cytoplasmic substitution lines, and cell fusion lines that hybrid weakness and sterility often arise from interactions between the nuclear genome and the chloroplast and mitochondrial genomes. These interactions are much more important in the origin and isolation of species than we appreciate. The strength of the post-zygotic barriers tends to be a function of cytoplasmic divergence. I also review evidence indicating that the properties and evolutionary potential of allopolyploids and diploid hybrid derivatives may be influenced by cytoplasmic factors.

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161 Hybridization and ecological divergence in sunflowers LEXER, CHRISTIAN Indiana University Entry into new and discrete ecological niches is theoretically difficult because it often requires simultaneous changes at multiple traits. One possible mechanism by which this difficulty might be overcome is transgressive segregation, which refers to the generation of extreme traits in segregating hybrid populations. Transgressive segregation is observed for many traits in artificial hybrids, and some authors have suggested that it might contribute to adaptation in nature. In annual sunflowers, the three wild species found in the most extreme habitats (sand dunes, desert floor, and salt marshes) all happen to be of hybrid origin. Possibly, transgressive segregation contributed to niche colonization. This hypothesis was tested by assessing whether (I) synthetic hybrids exhibited the transgressive phenotypes thought to be necessary for colonization of novel and extreme habitats; (2) transgressive phenotypes were favored by selection in nature; and (3) QTL combinations contributing to transgressive phenotypes in synthetic hybrids also occurred in the natural hybrid species. Results indicate that extreme traits found in natural hybrid species can be accounted for by transgressive segregation in synthetic hybrids. As expected, transgressive segregation in wild species is largely due to complementary gene action and the transgressive phenotypes and individual QTL are under strong directional selection in hybrid habitats. Finally, transgressive QTL combinations in synthetic hybrids are found in the natural hybrid species. Thus, transgressive segregation likely facilitated major ecological transitions in annual sunflowers.

162 Processes and patterns of intrinsic reproductive barriers in the Solanaceae LIVINGSTONE, KEVIN & RIESEBERG, LOREN H. Indiana University, USA Intrinsic, postzygotic reproductive isolating barriers have long been considered the gold standard for defining species because they demonstrate a closed gene pool, allowing independent evolutionary tracks. These barriers can arise from differences in individual loci t."tat cause incompatibilities (genic barriers) or from karyotypic rearrangements (chromosomal barriers). Despite the importance and seeming inevitability of these barriers, little is known about what kinds of genes are involved in incompatibilities and how and when they arise in the course of speciation; nor do we know how chromosomal rearrangements that cause impairment of fertility can become fixed differences between species. My research focuses on both of these questions using different genera and species within the Solanaceae as model systems. In my talk I will present data addressing the different manifestations and molecular basis of genic incompatibilities between the cultivated tomato, Lycopersicon esculentum, and a wild relative, Lycopersicon pennellii. In addition, patterns of chromosomal rearrangements within the Solanaceae will be used to address the role these rearrangements have played in adaptive divergence between species in the genus Solanum.

163 Hybridization as a mechanism of dispersal in oaks PETIT, R.J., BODENES, C., DUCOUSSO, A., ROUSSEL, G. & KREMER, A. UMR Biogeco, INRA, 69 Route d'Arcachon, F-33612 Cestas Cedex, France Orbitally-induced climate changes have forced species to shift their ranges. This has had long-lasting genetic consequences. In European oaks, the footprints of postglacial colonization can still be detected, in the form of patches several tens of kilometers in diameter where virtually all trees descend from the same maternal founder individual. Remarkably, this local spatial structure is shared across oak species. These patches have been interpreted as the consequence of founder events due to long-distance seed dispersal during postglacial expansion. Such a genetic structure, once established, is remarkably resilient, due to the high population sizes of mature oak forests and to the prevalence of pollen movements. On the other hand, adaptive traits related to species status may be disseminated through pollen flow. The resurrection of relatively pure oak species as a consequence of intense

ABSTRACTS 67

disruptive selection eventually results in 'nuclear capture' of incoming oak nuclear genomes by resident cytoplasms. Hybridization and introgression may therefore be viewed as mechanisms of dispersal. In fact, the succession of oak species (with the more pioneer species being replaced by late-successional ones) can have both a demographic and a genetic component, since hybridization is often asymmetrical. Other plant species may take advantage of related species to extend their ranges.

164 Integration of populations and differentiation of species RIESEBERG, LOREN H. Department of Biology, Indiana University, Bloomington The study of speciation is largely founded on two conceptual advances. The first was Darwin's proposal that species differences are caused by natural selection. The second was Ernst Mayr's formulation of the biological species concept, which emphasized the importance of gene flow for holding species together and reproductive barriers for keeping them apart. However, the primacy of selection has been challenged by speciation models emphasizing population bottlenecks, and the importance of gene flow has been disputed because migration seems too limited to keep conspecific populations from diverging. Here, I review evidence from recent genetic studies to evaluate these claims. With respect to selection, the majority of loci affecting species differences have effects in the same direction. This pattern is most consistent with divergence through directional natural selection; neutral divergence would result in a high proportion of loci with antagonistic effects. Likewise, there is sufficient gene flow in essentially all species to enable the spread of strongly favorable alleles, the most likely agents of collective evolution. Thus, gene flow probably does hold species together, but its traditional role as a force that constrains differentiation has been over-emphasized relative to its creative role as a mechanism for the spread of advantageous mutations.

165 Adaptive radiation and regulatory gene evolution in the Hawaiian silversword alliance (Asteraceae) ROBICHAUX, R.H. 1

, LAWTON-RAUH, A.2, & PURUGGANAN, M.D.3

1 Department of Ecology & Evolutionary Biology, University of Arizona, Tucson, AZ 85721 USA; 2Department of Genetics & Evolution, Max Planck Institute of Chemical Ecology, Jena 07745 Germany; 3Department of Genetics, North Carolina State University, Raleigh, NC 27695 USA The Hawaiian silversword alliance is a premier example of adaptive adiation, with the species exhibiting extensive and rapid diversification in reproductive and vegetative form. Molecular evolutionary analyses of the floral regulatory genes ASAP l and ASAP3rrM6 indicate a significant acceleration in nonsynonymous relative to synonymous substitution rates in the rapidly evolving Hawaiian lineage. Analyses further indicate that the Hawaiian species are allotetraploids, deriving from an ancient interspecific hybridization event involving species in two lineages of North American tarweeds. Molecular population genetic analyses of the duplicated ASAP! and ASAP3rrM6 genes indicate that two homoeologs (ASAP I-A and ASAP I-B) appear to be evolving in a similar fashion, whereas two other homoeologs (ASAP3fi'M6-A and ASAP3rrM6-B) have patterns of nucleotide diversity consistent with divergent evolutionary trajectories. This divergence suggests that selection may be partitioning the functional trajectories of these two regulatory gene copies. A multilocus study of six genes (ASAPl-A, ASAPl-B, ASAP3fi'M6-A, ASAP3fi'M6-B, ASCAB9 and ASNADl) among several Hawaiian silversword alliance species further indicates that recently-derived sibling species that exhibit significant morphological divergence show incomplete haplotypic divergence and genetic distances similar to levels expected between intraspecific populations. The extent of genetic divergence and historical demographics influencing diversification are also examined.

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166 Genomic hot spots of genetic differentiation between European sympatric oak species SAINTAGNE, CAROLINE 1

, MARIETTE, STEPHANIE2, BODENES, CATHERINE',

BARRENECHE, TERESA1, GOICOECHEA, PABLO 3

, ZANETTO, ANNE 4, PLOMION,

CHRISTOPHE 1, KREMER, ANTOINE 1

1/NRA, 69 route d'Arcachon, 33612 Cestas cedex, France; 2CEMAGREF, Domaine des Barres, 45290 Nogent-sur-Vernisson; 3NEIKER A.B., Granja Modelo de Arkaute-Apartado 46, E01080 Vittoria- Gasteiz; 4/NRA, BP 81, 33883 Villenave d'Ornon Pedunculate oak (Q. robur L.) and Sessile oak (Q. petraea (Matt.) Liebl. are closely related species with a widely sympatric distribution in Europe. When the two species coexist in the same stands, they show clear ecological preferences and morphological differences. A whole body of literature data shows that the phenotypic differentiation is associated to an extremely low genetic differentiation. One hypothesis for the discrepancy was related to the distribution of differentiation within the genome. When numerous markers were tested, it became apparent that a rare proportion exhibited larger allele frequency variation between the two species. These results clearly suggested that genomic regions involved in species differentiation are rare and explain why earlier molecular investigations using a low number of loci proved to be inefficient. We revisited previous genetic surveys conducted in natural mixed populations with different markers systems and computed interspecific Gst (Nei's genetic differentiation) values for all markers. Their distribution follows an L shaped curve. In a second step we detected QTLs for leaf morphological traits exhibiting interspecific phenotypic differences. The comparison of the distribution of interspecific Gst values and QTLs revealed some interesting co localisation. These two independent approaches confirmed the existence of hots spots of species differentiation in the oak genome.

167 Phylogenetic estimation of speciation and extinction rates SANDERSON, MICHAEL J. Section of Evolution and Ecology, University of California, Davis, CA, 95616 USA In the last 10 years quantitative methods for estimating speciation rates in clades have improved significantly. Better estimates for patterns of rate variation across plant groups have been obtained by combining these methods with new information about the divergence times of species, based on analysis of sequence data and the fossil record. In this talk I review statistical approaches to estimating diversification rates and evaluate their dependence on the accuracy of divergence time estimates. I also discuss two critical complicating factors: the role of extinction in causing biased inferences, and the difficulty of modeling the diversification process in a realistic fashion. Finally, I discuss examples of estimating speciation and extinction rates at two very different phylogenetic scales: among major clades of angiosperms, and between selected recent radiations for which good geological time calibrations are available.

168 Adaptive divergence and speciation in wild rice ( Oryza) SANG, TAO, LI, CHANGBAO & ZHOU, AILING Department of Plant Biology, Michigan State University, East Lansing, MI 48824 Adaptive divergence plays an essential role in phenotypic evolution and speciation. The populational genetic model of adaptation predicts that the phenotypic sizes of favorable mutations fixed during an adaptive walk decrease exponentially as the population moves toward the fitness optimum. The wild progenitors of the cultivated rice (Oryza sativa), Oryza nivara and Oryza rufipogon offer an ideal experimental system to test this hypothesis. Phylogenetic analyses based on multiple gene sequences suggested that 0. nivara was derived from the 0. rufipogon-like ancestor as a result of habitat shift from deep-water swamps to seasonally dry habitats. Despite the recency of divergence (less than 0.3 million years ago), the two species have shown remarkable differentiation in life history, reproductive allocation, breeding system, seed dispersal, and photoperiodism. The genetic basis of the adaptive differentiation is being studied through QTL mapping. The loss of photoperiod sensitivity must have been

ABSIRACTS 69

among the earliest mutations fixed during the adaptive walk leading to the origin of 0. nivara. Being a short-day plant, Oryza rufipogon does not flower early enough to produce seeds before the dry season and would have zero fitness in the seasonally dry habitats. In rice cultivars, the loss-of-function mutation of the Hdl gene explains a large portion of the phenotypic variation of photoperiod sensitivity. Our greenhouse experiments and DNA sequencing analyses indicated that the loss-of-function mutation of the Hdl gene is correlated with the photoperiod insensitivity in 0 . nivara accessions. A transgenic experiment has been conducted to determine whether the single­gene mutation accounts for the Joss of photoperiod sensitivity of 0 . nivara, and consequently to test whether favorable mutations fixed initially in adaptation have major phenotypic effects.

169 The dynamics of polyploid establishment in flowering plants SCHEMSKE, DOUGLAS W1.& RAMSEY, JUSTIN2

1 Department of Plant Biology, Michigan State University, schem@msu.edu, 2 Department of Botany, University of Washington, Seattle WA 91891, and Present address: Department of Botany, University of Guelph, Guelph, Ontario, Canada N1G 2W1, email: jramsey@uoguelph.ca Nearly half of all flowering plants species are the result of whole-genome doubling, i.e. polyploidy. The mechanisms by which a neopolyploid is able to invade the population of its progenitor differ from those involved in the fixation of a new adaptive mutation in a homoploid population. Unlike the selective advance of a new adaptive mutation, a neopolyploid is nearly or entirely reproductively isolated from its progenitors. While the more abundant progenitor will mate principally within a cytotype, inter-cytotype matings will be the rule for the neopolyploid, and these typically produce far fewer progeny which suffer from low viability and fertility. Although a new cytotype may be ecologically differentiated from its progenitor and may achieve superior viability or fertility, frequency-dependent mating success results in the exclusion of the minority cytotype. The dynamics of polyploid establishment has been investigated in a number of models using a variety of approaches. All models examine the dynamics of a single population, and all identify the conditions for coexistence of a polyploid with its progenitor, as well as those leading to the replacement of one cytotype by another. The models generally assume annual populations and deterministic dynamics and it is assumed that intercytoype matings fail, e.g. triploids are not produced in a mixed population of diploids and tetraploids.

The results from these theoretical efforts demonstrate that by virtue of their low initial frequency, and the low success of intercytotype matings, neopolyploids possess an inherent disadvantage that can be overcome by a variety of mechanisms, including: 1) fitness differences, 2) ecological differentiation, 3) selfmg or apomixis, and 4) a high frequency of unreduced gamete formation by the progenitor cytotype. Nevertheless, most authors conclude that the conditions under which polyploids can successfully coexist with their progenitor cytotype are quite restrictive. Coexistence often requires parameter values that are very different from those observed in natural populations. A fundamental assumption shared by all published models is that the invasion and spread of polyploids occurs within a single population. Here we provide the results of computer simulations that investigate the dynamics of polyploid establishment. We propose that the distinguishing feature of polyploid establishment not included in previous models is the potential for neopolyploids to possess such profound ecological differences as to allow them to occupy habitats unsuitable for their progenitor. Such ecological differentiation could provide substantial reproductive isolation, and thus overcome the frequency-dependent minority disadvantage. Ramsey, J. and D. W. Schemske. 1998. Pathways, mechanisms and rates of polyploid formation in flowering

plants. Ann. Rev. Ecol. Syst. 29:477-501. Ramsey, J. and D. W. Schemske. 2002. Neopolyploidy in flowering plants. Ann. Rev. Ecol. Syst. 33:589-639.

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170 Polyploidy and speciation #SOLTIS, D.E. & SOLTIS, P.S. Department of Botany, University of Florida, Gainesville, FL 32611 Florida Museum ofNatural History, University of Florida, Gainesville, FL 32611 Grant dedicated four chapters of Plant Speciation to the topic of polyploidy, covering range and frequency of polyploidy, types ofpolyploids, factors promoting polyploidy, and the polyploid complex. Much of Grant's text remains relevant today, but some areas have seen dramatic changes in the past 20 years. Genetic and genomic investigations have provided unparalleled insights into the genetic architecture of polyploids. It now appears that all angiosperms are polyploid to some degree. Some polyploid genomes are highly dynamic and have experienced considerable rearrangement, while others have been relatively stable. Genomic downsizing has occurred following polyploidization in some cases, but not others. Genetic tools have clarified duplicate gene evolution in polyploids, as well as the extent and mechanisms of gene silencing in polyploid species. Epigenetic phenomena may play a major role in gene silencing, and the potential role of subfunctionalization of duplicate genes is becoming apparent. The prevalence and genetic consequences ofautopolyploidization were unappreciated 20 years ago. Similarly, multiple origins of polyploids, largely uninvestigated prior to the 1980s, are now known to be the rule, with important genetic consequences for natural populations. Despite new understanding of the genetic and genomic attributes of polyploids, progress in other areas has been minimal. For example, little is known about the ecological and physiological attributes of polyploids relative to their diploid progenitors.

171 Hybridization and speciation in Gossypium WENDEL, JONATHAN F. Dept. of Ecology, Evolution, and Organismal Biology, Iowa State Univ., Ames, /A 50011 USA The cotton genus includes approximately 50 species distributed in arid to semi-arid regions of the tropics and subtropics. Gossypium species exhibit extraordinary morphological diversity, ranging from herbaceous perennials to small trees and having a great variety of floral and vegetative features. A parallel level of cytogenetic and genomic diversity has evolved during the global radiation of the genus, with the eight diploid (all n = 13) genome groups varying 3.5-fold in genome size. Phylogenetic analysis and molecular clock calculations suggest that the genus originated 5 - 10 million years ago, and that the major genome groups arose in rapid succession following formation of the genus. This evolutionary history has included multiple episodes of trans-oceanic dispersal, invasion of new ecological niches, acquisition of specialized reproductive syndromes, and a surprisingly high frequency of interspecific hybridization and hybrid speciation among lineages that presently are inter-sterile. One modem diploid appears to have a complex history of cryptic trysts with lineages from two hemispheres. A chance biological reunion among diploid lineages isolated in different hemispheres for millions of years led to the monophyletic origin of American polyploid cottons, which subsequently radiated into lineages represented by five extant species.

172 The ecology of plant speciation WHITTON, JEANNETTE Department of Botany and Centre for Biodiversity Research, The University of British Columbia, Vancouver, BC, V6T 1Z4 The role of ecology in plant speciation, whether acting directly to bring about reproductive isolation through ecological speciation or indirectly by allowing ecological persistence, is generally poorly characterized. Minimally, niche shifts can facilitate the establishment of reproductive isolation. In addition, under ecological speciation, divergent natural selection acting on ecological tolerances can drive the evolution of reproductive isolation. Verne Grant (among others) noted strong divergent selection is easily imposed by the edaphic environment. Indeed, edaphic specialists such as occur on serpentine or highly saline soils provide the best evidence for ecological speciation in plants. Although there are relatively few well-studied systems, these suggest

ABSTRACTS 71

two trends. First, reproductive isolation may be a common byproduct of ecological divergence. For example in Lasthenia ca/ifornica, levels of reproductive isolation increase along with ecological divergence between populations. Second, parallel evolution of reproductive isolation is also a likely outcome of ecological selection. These trends suggest that the contribution of divergent natural selection to the evolution of reproductive isolation in plants merits considerable attention as it is likely substantially under-appreciated. Furthermore, I suggest that the study of edaphic adaptation may be among the most fruitful avenues for future research to clarify the extent of ecological speciation in plants.

173 Mating system evolution and speciation in monkey flowers WILLIS, JOHN H. & FISHMAN, LILA Department of Biology, Box 90338, Duke University, Durham, NC, 27708 The genetic basis of species differences provides insight into past evolutionary change and has long been a subject of contention among evolutionary biologists. In this study, we investigate the genetic architecture of phenotypic differences and reproductive isolation between two flowering plant species with highly divergent mating systems: Mimu/us gutta/us ( outcrossing) and M. nasutus ( selfing). Using a large number of molecular markers, we identified a total of24 quantitative trait loci (QTLs} underlying seven floral traits associated with the divergent mating systems. Variation in each floral trait was caused by at least II QTLs, and almost all QTLs affected more than one floral trait. Nearly all of the QTLs had very small effects. We also used this map to investigate the genetic basis of partial postzygotic reproductive isolating barriers. We found evidence ofDobzhansky-Muller incompatibilities and nucleo-cytoplasmic interactions responsible for partial male and female hybrid sterility, and have begun to characterize the underlying loci. These investigations provide an unusually detailed view of the complex genetic changes that occurred during the evolution of self-fertilization and reproductive isolation, and set the stage for future investigations into the molecular genetic basis of these traits.

ADDITIONAL ORAL PRESENTATION ON PLANT SPECIATION GIVEN IN SESSIONS FOR PLANT CANADA

36 Population genetics of speciation in the Hawaiian endemic plant genus Schiedea FILATOV, DMITRY A. School of Biosciences, University on Birmingham, Edgbaston, Birmingham B15 2TT, UK (for abstract see Plant Canada oral presentations)

44 Molecular phylogeny of Populus (Salicaceae) reveals reticulate evolution *HAMZEH, M. & DAY ANANDAN, S. Biology Department, Concordia University, Montreal, QC, H3G JM8 (for abstract see Plant Canada Oral Presentations)

72 Plant Canada 2003

82 Ploidy level variation and breeding behaviour of Crataegus (Rosaceae): Data from flow cytometry *TALENT, N. & DICKINSON, T.A. Center for Biodiversity and Conservation Biology, Royal Ontario Museum, Toronto, Canada M5S 2C6 and Department of Botany, University of Toronto, Toronto, Canada M5S 3B2 (for abstract see Plant Canada Oral Presentations)

83 Patterns and implications of multiple autopolyploid origins in apomictic Easter daisies *THOMPSON, STACEY L., CHOE, GINA & WHITTON, JEANNETTE. Department of Botany and Centre for Biodiversity Research, University of British Columbia (for abstract see Plant Canada Oral Presentations)

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Plant Speciation - Contributed Poster Presentations

(Note: includes selected titles from Plant Canada 2003 associated with speciation)

174 Mechanisms of ecogeographic isolation between Mimulus cardinalis and M. lewisii ANGERT, A.L. & SCHEMSKE, D.W. Department of plant Biology, Michigan State University, East Lansing, Michigan Reproductive isolation is critical for the origin and maintenance of species differences. Because isolating barriers act sequentially throughout the life history of an organism, late-acting barriers to mating prevent only that fraction of gene flow that is not prevented by earlier acting barriers. For this reason, ecogeographic isolation is an important through frequently overlooked reproductive barrier. Here we examine the mechanisms contributing to ecogeographic isolation between the interfertile sister species Mimulus cardilUllis and M. lewisii. In the central Sierra Nevada Mountains of California, M. cardinalis occurs from 0 - 1800 m whereas M. lewisii occurs from 1200 - 3000 m. Reciprocal transplant gardens show that each species achieves highest fitness within its elevation range. M.lewisii experience 100% mortality at low elevation. Although M. cardinalis survival is high at all sites, its reproductive success drop to 0 at high elevation. Growth chambers simulating low and high elevation temperature regimes replicate the fitness differences observed in reciprocal transplants. Taken together, ecogeographic isolating mechanism related to temperature tolerance reduce the probability of co-occurrence and the opportunity for hybrid formation between M. cardinal is and M. lewisii throughout their ranges.

175 The Phlomis X composita hybrid group viewed under the recombinational speciation evolutionary scenario APARICIO, ABELARDO & ALBALADEJO, RAFAEL G. Departamento de Biologfa Vegetal y Ecologfa, Facultad de Farmacia, Universidad de Sevilla, Espana Phlomis is a Mediterranean and Irano-Turanian genus in the Lamiaceae where interespecific hybridization seems to be common. Polyploid and allopoplyploid species are rather frequent in the plant kingdom; contrarily, diploid hybrid species are scarce, and in fact, only a few cases have been rigorously documented in nature. We are now examining population genetics' theoretical predictions for the likelihood of homoploid hybrid speciation in the P. X composita group (P. lychnitis X P. crinita) in Spain (Iberian Peninsula). Morphometric analysis, ecological data and allozyme variation supported an ecogeographical pattern of distribution and their frequencies of hybrid forms. Moreover, reproductive biology experiments revealed that hybrid forms are relatively fertile with very weak or even null reproductive isolation barriers to parental plants, and chromosome structure differences were also minimal. Thus, backcrossing, introgression and gene flow are, at present, the rules in this case study. Given that homoploid hybrid speciation is a punctuated process, all the interpretations in this hybrid group should be focused within this evolutionary scenario where rapid chromosomal reassortment could raise effective isolation reproductive barriers.

176 Study of chloroplast and mitochondrial DNA diversity in the natural populations of Gaultheria fragrantissima in the two hotspots in India APTE, G.S.* 1

, LAGU, M.D.2, RANJEKAR. P.K.3 & GUPTA, V.S.4

Division of Biochemical Sciences, National Chemical Laboratory, Pune-411008, India Gaultheriafragrantissima occurs only in the two hotspots in India, Western Ghats (WG) and Northeastern Himalayas (NE). It is a medicinally important plant where the oil from its leaves known as 'Oil of Indian Wintergreen' is used in most of the pain balms. PCR- RFLP technique was used to study chloroplast and mitochondrial DNA diversity in its natural populations. Eight cpDNA and seven mtDNA haplotypes were detected

74 Plant Canada 2003

from eight populations. None of the cpDNA haplotypes is shared by all the populations. Four cpDNA haplotypes are unique to WG and four toNE region. One mtDNA haplotype is shared by all the populations and is the most common haplotype. Three mtDNA haplotypes are common to both the hotspots, three are unique to WG and one to NE region. CpDNA diversity (h,.= 0.639) is higher as compared to mtDNA diversity (h,.= 0.582). However within population diversity is higher in mtDNA (h5= 0.467) than cpDNA (h5= 0.224). The level of population subdivision for unordered and ordered alleles is much higher in cpDNA (Gs-r= 0.650; Ns-r= 0.841) as compared to mtDNA (G5,.= 0.197; N5,.= 0.252). Higher value of NsT than GsT in both cp and mtDNA reveal high differentiation among population.

177 Biochemical adaptation to soil moisture in a Rocky Mountain wildflower BLACKMAN, B.K. & RUVINSKY, J.R. Department of Biology, Stanford University, Stanford, CA 94114 and Rocky Mountain Biological Laboratory, Crested Butte, CO 81224 Functional studies in evolutionary genetics are required to distinguish between competing hypotheses regarding which evolutionary processes generate patterns of genetic variation. Such investigations foster mechanistic insight into the consequences of allelic variation for organismal fitness in the field. Here, we present evidence that natural selection by water stress maintains an allozyme polymorphism in 6-phosphogluconate dehydrogenase (6PGD2

)

alleles in lpomopsis aggregata. Observations that favor an adaptive explanation include: I) reproducibility of a correlation between the 3 allele (6PGD2-3) and soil moisture in two years, 2) presence of the correlation in a set of geographically isolated populations and in local subpopulations subject to heavy gene flow, and 3) discovery of two isolated high-frequency sites. We also demonstrate in situ an allele-specific effect in the response of plant performance to different soil moistures. For only those genotypes carrying 6PGD-3, plant performance--as measured by plant size--significantly correlates with soil moisture, with carriers performing better in wet sites, and worse in dry sites, relative to non-carriers. The strong selection observed, as indicated by population divergence despite gene flow and measurability of allelic impacts on performance, demonstrates that this is a promising system for the study genotype-phenotype-environment interactions and their role in evolutionary process.

178 Maximum-likelihood estimates of hybrid index based on molecular markers BUERKLE, C. ALEX Department of Biology, University ofWisconsin-Eau Claire, Eau Claire, WI 54702, USA Hybrid zones are natural settings for the study of barriers between species. Much of the research in hybrid zones benefits from estimates of the relative contribution of parental genomes to the individuals encountered. Various methods exist for estimating the hybridity of individuals based on genetic and morphological characters. This presentation develops a maximum-likelihood estimate of a hybrid index based on dominant and codominant genetic markers. Dominant markers have an inherent ambiguity because homozygous present and heterozygous genotypes can not be distinguished, and this lack of resolution is incorporated in the calculation of the hybrid index. In contrast, genotypes of codominant markers can be fully resolved and typically involve a larger number of alleles per locus. The potential information content of each class of marker is described, as is the effect of the number of loci on confidence intervals for the hybrid index. The calculation of the hybrid index is implemented in stand-alone software and is available from the author (http://www.uwec.edu/buerklalhindex).

ABSTRACTS 75

179 Catching the rays: Detecting hybridisation and introgression in the genus Senecio (Asteraceae) CHAPMAN, MARK A. & ABBOTT, RICHARD J. Sir Harold Mitchell Building, School of Biology, University of St Andrews, St Andrews, FIFE, KY169TH, UK The introgressive or hybrid origin of a number of plant species has been proved using molecular markers. Such markers are generally thought to be neutral and therefore their role in the new species is unknown. Here we use cycloidea genes as a marker for introgression in the genus Senecio. Two members of the cycloidea gene family are very tightly linked to the gene controlling presence/ absence of ray florets in Senecio. We have used these genes to examine the origin of two disjunct subspecies of the tetraploid Senecio mohavensis. Secondly, we have used cycloidea genes to determine the parentage of the hexaploid S. teneriffae, a Canary Island endemic, closely related to the British neohexaploid S. cambrensis.

180 Phylogenetic reconstruction of the genus Fragaria using intron sequence from a protein encoding nuclear gene DIMEGLIO, L.M., DEHAAN, K.P., STAUDT, G., & DAVIS, T.M. Genetics Program, University of New Hampshire, Durham, NH 03824 The history of the genus Fragaria involves two important evolutionary phenomena, hybridization and chromosome doubling (polyploidy). The octoploid, cultivated strawberry, Fragaria x ananassa, is a hybrid between two wild octoploid species, F. chiloensis and F. virginiana; however, its ancestry has not been traced to the diploid level. We performed parsimony and Bayesian inference phylogenetic analyses on intron sequence data from the alcohol dehydrogenase gene to reconstruct the phylogeny of the genus and identify the diploid progenitors of the cultivated species. Our analyses included data from thirteen diploid and five polyploid Fragaria species, and one outgroup species, Potentilla fruticosa. Multiple alleles for each allopolyploid species were detected and all unique sequences were included. Our data contain several phylogenetically informative gaps, and we have explored methods to incorporate them into the analyses. The resulting trees form two clades, clade A and clade B, with limited resolution at the terminal branches. Each wild octoploid has alleles in both clade A and clade B, suggesting at least one diploid contributor from each clade. Although not thoroughly resolved, these trees implicate diploids F. vesca from clade A and F. iinumae from clade B as likely progenitors of the octoploid species.

181 Identification of the signature selection in Helianthus paradoxus using microsatellite polymorphisms EDELIST, CECILE Department of Biology, Indiana University, Bloomington, IN 47405 The diploid hybrid species H. paradoxus inhabits salt marshes, when both of its parental species, H. annuus and H. petiolaris, are salt sensitive. Several QTL responsible for survival in a saline environment have been identified in BC2 hybrids between H. annuus and H. petiolaris, including fourteen mineral ion QTLs and three survivorship QTLs. These three survivorship QTLs may have been under selection during the formation of H. paradoxus. Theory predicts that loci under selection should have lower variance than neutral loci. In hybrid speciation, this should apply to entire chromosomal blocks. Currently, we are comparing the levels of variability in microsatellites linked to the three selected survivorship QTLs with others elsewhere in the genome. We are replicating this work on three different wild populations of H. paradoxus.

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182 Speciation in facultatively apomictic Hieracium subgen. Pilosella taxa: a bottom-up approach FEI-plliR, J.1.2, KRAHULCOV A, A. 1

, KRAHULEC, F. 1, GEMEINHOLZER, B.3 &

BRAUTIGAM, S.2

1 Institute of Botany, Academy of Sciences of the Czech Republic, 25243 Pr _honice near Prague, Czech Republic. 2State Museum of Natural History, P.O. Box 300I54, 02806 Garlitz, Germany. 3 Institute of Plant Genetics and Crop Plant Research, Corrensstr. 3, 06466 Gatersleben, Germany

Facultatively apomictic taxa present special difficulties for the elucidation of speciation processes. A vast number of (micro)species and a virtual continuity of forms make their identification and treatment a challenging task. Therefore, we started at the clonal level by multilocus fingerprinting in order to assist with their proper determination and taxonomic delimitation as a foundation for further studies and to determine the number, origin and geographic distribution of clones present in different apomictic taxa. A mixture of basic species, old fixed intermediate forms and recent hybrids was found. Next, we studied hybridization and introgression phenomena of the confirmed taxa at population and species level using sequences and structural properties of the trnT -trnL intergenic spacer. Despite multiple origins of clones, most of the presumed hybrids obtained their chloroplast DNA from the same parent and often, the facultative apomict even proved to be the maternal parent rather than the sexual species. Finally, a molecular phylogeny of all Pilosella basic species was established based on chloroplast as well as nuclear (ITS) sequences. Discrepancies between them reflected either morphologicaVcytological or distributionaVecological features. The molecular approaches were accompanied by morphological and cytological analyses as well as by studies of reproduction systems and experimental hybridizations.

111 Characterizing the genetic basis of quantitative trait differences between ecotypes of A vena barbata using recombinant inbred lines. *GARDNER, K.M., LATTA, R.G. Dalhousie University, Halifax, Nova Scotia, B3H 4H6 (for abstract see Plant Canada Poster Presentations)

183 Evidence for an adaptive radiation in the Agave's GOOD-A VILA

3 SARA V. 1

, SOUZA, VALERIA 2, CASTILLO, AMANDA2, GAUT,

BRANDON G. & EGUIARTE, LUIS E. 2

1 Department of Biology, Acadia University, Wolfville, Nova Scotia, Canada, B4P R62; 2Departamento de Ecolog(a Evolutiva, Universidad Nacional Aut6noma de Mexico, D.F., Mexico; 3Department of Ecology and Evolutionary Biology University of California, Irvine, California, USA In this study we aim to understand the phylogenetic limits and time of origin of the family Agavaceae and to explore the possibility that there has been an adaptive radiation in its most species rich genus, Agave sensu lato. To this end, we present an original analysis of the phylogenetic relationship of the monocots using 334 sequences of rbcL obtained from genbank, 24 dicot and l gymnosperm sequence to root the tree. We generate the topology of the tree using maximum parsimony and estimate branch lengths using maximum likelihood. This information is used to estimate the age of all internal nodes using penalized maximum likelihood and the age of the gymnospenn/ angiosperm split (132 MYA) to calibrate rates. Next we combine some original and genebank sequences for both nuclear (ITS intergenic region) and chloroplast (two intergenic spacers) genes to examine patterns and rates of speciation in the highly diverse group, Agave sensu lato, that includes more than 200 species. These analyses of molecular data are combined with information on the life-history characteristics of Agave species, in particular the existence of monocarpy, giant rosettes and pollinator syndromes. We find that the genus Agave has a relatively

ABSTRACTS 77

' Index of Authors

i ABBOIT, R.1 ................................................ 62, 76 BOOIJ-1AMES, I.S ............... ............ ........ .... ..... 53 ABRAMS S.R ..................................................... 48 ABRAMS, S ....... ..... .......... ..... ........................ ..... 15

BOUCK, A. C •.................... ...... .. ................... ..... 62 BOWN, A.W .... ..... .............. .......... ................. ..... 13 I

ADONGO, L ....................................................... 39 BRAUTIGAM, s ............................... .. ........... .... 77 AINOUCHE, M.L ............................................... 62 ALBALADEJO, R.G .................. ..................... ... 74

BREITWIESER, !. ............................... .. .. ........... 88 BRISSON, N ... .... .......... ............................... ... ... . 16 (

ALLAN, W.L . ........ .. ... ................... ...... ..... .......... 39 BROUILLET, L .................................................. 42 ALLARD, 1 . ........................................................ 16 BROWN, A.H.D ........................................... 63, 79 ALLEN, G.A .......... ...... .......... ... .................... 61, 89 BROWN, C.M .................................................... 43 ALLY, 0 .. ........... ................ .............. .... .......... ..... 86 BROWN,K ......... ............. .................. ... ....... ..... .. 22

AMBROSE, S. J. ................................ ............... .. 15 BROWNFIELD, D.L.. .......................... ... ... ..... ... 47

ANDERSON, E.M .. .. ......... .................. ............... 39 BRUN, F.G .................................. ... ........... ..... .... 83 ANGERT, A.L .......... ...... ...................... ...... .... .... 74 BRUN, FERNANDO G . .... ..... .. ......................... 83 ANYIA A.O ........................................................ 11 BRUNEAU, A ................................................. .. . 14

APARICIO, A ..................................................... 74 BRUNEAU, A . ........... .................... .... ........ .. 19, 34

APTE, G.S ................................ ........ ... .. .............. 74 BRUZZESE, B.M ............... ... ....... ........... ........... 43 ARCHAMBAULT, A ......................................... 40 BUDD,K ....... ............. ...... ..... ........... ............ ...... 52

ARCHAMBAULT, D.J ...... ....... ........ ..... ............ 11 BUERKLE, C.A ........... .......... ... ......................... 75 ARNOLD, M.L .... ..................................... .... ..... 62 BURKE,D ... .... ................ .. ...... ... .... .................... 89 ARROYO, 1 ......................................................... 84 BURNS, R.A ...... ... .................... .. ...... ....... ........ .. . 44 ASAMI, T ................ ..... .... ......... ........................... 6 BYUN MCKAY, A ..................................... ... .. . 14 A ITIEH, J. ........... ... .. ... ..... ............... ................... 25 CAMPBELL, D.A .............................................. 44 AUNG, T •..... ....... ....... ................... .... ................. . 60 CAMPBELL, D.A .................................... 8, 27, 43 A VILA-SAKAR, G . ... .............. .. ... ... ..... ............. 51 CAMPBELL, D.R .................. ..................... 63, 91 BACKOR, M ....... ..... ........... ............ ........ .. .. .... .... 18 CAMPBELL, 1 ........ ... ......... .................. ...... ... ..... 44 BADGER, M.R ......... .......... ............. ...... ............. 55 CARR, B ............................................................. 45

BAIN, 1. F ............ .... .................................... ........ 40 CASTILLO, A .................................................... 77 BALSERIS, A .. ......... ...... ............. ..... ....... ........... 11 CHAPMAN, M.A ............................................... 76 BARABE, D ........................................................ 40 CHAUVET, E . .. ............. ..................................... 54 BARKLEY, T.M ................. ................................ 42 CHIASSON, D.M ............................................... 15 BARLOCHER, F . ............................. ......... ......... 30 CHIWOCHA, S.O.S ........................................... 15 BARNETT, D.T . .......... ..... ................. .. ................ 3 CHOE, G ....................................................... 36, 73 BARRENECHE, T .............................................. 69 CHORY,J ............................................................ 6 BARTISH, I.V ..................................................... 84 CHURCH, S ........................................................ 63 BASSEL, G.W .................................................... 41 CLARK., S.M ...................................................... 45 BASSET, G ......................................................... 12 COLMAN, B ........................................ .............. 46 BASSET, G ........ ..... ..... ....................................... 32 CORNMAN, R. S ........ ....... ............................... 62 BAUMEL, A . .................... .................................. 62 COULAS, 1.A . .................................................... 45 BAZEL Y, D. R .. .. ...................... ............................ 4 DADSWELL, M.J ................ ......................... ..... 53 BEAUDETTE, P ................... ... .......................... 41 DALE, M.R.T •.................. .... ........... ...... 16, 29, 55 BELLAND, RJ .................................................... 20 DALE, P.L ............ ..................... .... .. .. ................ 46 BEWLEY, 1.0 ......... .. .............. ............................ 41 DANGL,J ........................................................... 16 BIRD, D. A ........... ........... ... ........... ... ............. ...... 12 DANKERT, B ............. .......................... ...... ........ 27 BLACKMAN, B.K ....................................... 42, 75 DASON, J.S ........................................................ 46 BLADE,S ........................................................... 46 DAVIS, A.R ........................................................ 46 BLADE,S . ......... .... ... ......................... .. ............. .. 59 DAVIS, T,M . ...................................... .. ... ........... 85 BLOCK., A.K ..... ................ ......... ..... .. ........ .... ...... 42 DAVIS, T.M ........................................ ... ............ 76 BLOMT ... ................. ..... ...... ........... ... ...... ..... ...... 53 BODENES, C . ... ........ .......................... .... ...... 67, 69

DAY,M .............................................................. 16 DAYANANDAN, S ....... ..... .. ................... .... ... ... 72

BOHLMANN, J ....... ............... ... ... ................. .... 14 DAY ANAND AN, S ........................................... 21 BONHAM SMITH, P.C .................................... .48 DECH, J.P ........................................................... 47 BONHAM-SMITH, P.C ..................................... 12

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DECKERT, R.J . ....... .. ...... ..... ................... .... ...... ... 2 GIBBY, M .......... ... ... .. ... .. ......... ... ... ...... ............... 90 DEHAAN, K.P ................ ... ....... ..... ....... .. .... ....... . 76 GIFFORD, D.J ... ............. ... ...... ... ...... .. .. .............. 47 DELLACASA, S ......... ...... ... ....... ... .................... . 88 GIJZEN, M . ........... ...... ............. ................ .......... 27 DEMAY, S ......... ..... ..... ... ....... ..... ........................ 90 GILLESPIE, L . ... .... .. ... .................. ...... .... ..... ...... 40 DESPRES, C . ........... ..... .. .. ........... .................... ... 16 GILMER, S . ............ ................ .................... ........ 48 DESVEAUX, D . ...... .. .. .......... .. .......... ..... .......... .. 16 GIVNISH, T.J. ... .......... ............................... ........ 64 DI BERNADINO, N . .. ... .... .. ...... .. ..... ..... .. ........... 88 GOICOECHEA, P . ................ .................. ........... 69 DICKINSON, T.A ............ ..... .. ..... ... 17, 30, 36, 73 GOLDEN, J. L ................ ......... ..... ................ ...... 40 DIGUISTINI, 5 ....... .. ........ .... ... .... ..... ................. 14 GOOD-AVILA, S.V ................... .. .. .................... 77 DIMEGLIO, L.M ........ ... ... .... ........... ....... .. ... ....... 76 GOTTLIEB, L.D . ................. ... .. ....... ............ .. .... 64 DIOCHON, A.C ................... ... .. .... .. ........ ... ... ...... 17 GOULD, J. ... ... .......... ..... ............ ... ........... ........ ... 20 DJIANA, R ...... .......... ... ........... .. .. ... .................... . 25 GRAY, G.R .......... .. ... .................... .... .................. 56 DOYLE, J.J .... ... .. ... .... .... .... .... .. ..... ......... 63, 79, 80 GRAY1

, G.R .. ... .. ..................... ........................... 20 DOYLE, J.L ................ .. .... ...... ................ ..... .. .... . 63 GREGORY, 1 ........................ .............................. 12 DUCOUSSO, A . ....... .. ......... ... .... .............. .......... 67 GREGORY, J.F. III ............................................ 32 DURNFORD, D . ....... ... ... .. .. .................. .......... 7, 28 GREGOR Y-EA YES, I ................... ...................... 9

DURNFORD, D.G ..... .. ... .. .. .. ....... .......... ....... 50, 58 GRETES, M . .... ........... ..................... ........ ........... 48

DYER, J.M .... .... ... ...... ... ..... .. ........... ......... .. ........ . 50 GRETZ, M. R .......................... .... .. ....................... 1

EDELIST, C .. .............. ........... ............................. 76 GROSS, B.L ......... ..... .............. .. .......................... 78

EGUIARTE, L.E ........... .......... ... ... ........... ........... 77 GUDYNAITE-SA VITCH, L., .... ....................... 48

ELIZABETH F .... .... ... ................. ........................ 81 GUINELF ........ ... ............................................... 45

EMERY, N •.. ....................... ... .... ... .............. .41, 45 EMERY, R.J.N ...... ....... ...................................... . 31

GUINEL, F.C ......... .................... ......................... 32 GUNASEKARA, S ...... ............ .......................... 21

ETIENNE C ............................... ... ...................... 17 GUPTA, V.S ....................................................... 74

ETIENNE, C ....................................................... 25 HAMZEH, M ................................................ 21, 72

FACCHINI, P. 1 .................................................. 12 HANNOUFA, A ...................... ........................... 22

FAHSELT, D .................... ............ ....................... 18 HANSON, A ... ....... ..... ............ .. ... ............ ........... 12

FAUBERT, E.A . .. ...... ............................... ......... . 14 HANSON, A.D . ....................... .... ....................... 32

FEHRER, J . ....... .......... ..... .... ..... ............... .... ....... 77 HARDHAM, A.R .. ....... ...................................... 35

FENNIAK, T ................. .. ......................... ........... 27 HASEGAWA, M .... ................ ............................ 78

FERGUSON, B ...... ..... .......... ... ................ ........... 45 FEURTADO, J. A . ...... ... ... ...... ................ ... .. ....... 15 FILATOV, D. A .......... ................. ................ ...... . 18 FILA TOY, D.A ................................................... 72

HAUFLER, C ........................... ... ....................... 64 HAY,M.E ........ ..... ..... ... ......... ............................... 1 HAZEL,S ............ ..... ............................. ............. 49 HEATH2

, D ...... .......................... ......................... 20

FINNEY, B.P ...................... .................................. 9 HEFFERON, K.L ............................................... 21

FIRANSKI, C ........................................................ 4 HENDERSON, A ..... .......................................... 90

FISHMAN, L .................. ..................................... 72 HERMANUTZ, L ......................................... 36, 59

FLORES-BERRIOS, E .. .......................... ........... 78 FOBET, P . ..... ........................... .......................... . 16 FORNEY, C.F .............................. ... .................... 56

HERMANUTZ, L.A ......................................... 31 HERNANDEZ-VERA, G .................................. 78 HETU, M.-F ......................... ...... ......................... 22

FOUGERE-DANEZAN, M .......................... 14, 19 HICKLENTON, P.R .... ....................................... 53

FRANCESCHI, ¥ . ............ ... ............................... 12 HILL, N •........ .............. ....................... ..... .. ... 29, 49

FRASER, S.F ......... .... .. ... .... .. ...... ........................ 19 HISCOTT, J . ........ .......... ........ ............................. 49

FREDEEN, A.L ................... .... ................ ...... 19, 43 HODGES, D.M ............ .......... .... ........... ........ 49, 56

FREDEEN, ARTHUR L .............. ......... .......... .. .. 44 HODGES, S ......... ... ....... ..................................... 92

GADAPATI, W ............ ............ ....... ....... ............. 20 HODGES, S.A ........ ....... ........ .. ... ...... .................. 65

GALKA,M . ........ ................... .. ................ .......... . 48 HODGES, S.A ...... ............... ... ... ............. ............ 90 GALKA, M. M ..... .... ........... .... .. ............ ... ....... .... 15 HOLLINGSWORTH, P.M ....... ............. ............ 90 GALWAY, M.E . ....... ....... ........ ....... ....... ... ... ....... 22 HOOVER, G,J •.... ...... .. ......... ..... ..... .................. 58 GARBARY, D.J ........................ . 17, 19, 22, 23, 29 HUBBARD, C.B . ......... ... ....... .. ... ......... .............. 22 GARDNER, K.M ......... ......... .... ............. ....... 47, 77 HUERTAS, l.E . .................... .... .............. ............ 46 GAUT, B.G . .............. ......... .. .. ... .............. ............ 77 HUMBY, P.L ........ .......................... ....... ............. 50

GEMEINHOLZER, B ... ... ......... ............ .. ............ 77 HUNER,N .... ........... .... ........ ..... ........... ..... ............ 7

GERRATH, J.M ..... .. .... .. ... .......... ............. ........... 23 HUNER, N.P .A ...... ....... ... .. ..... .... .... .... .... ll, 48, 53

ABSI'RACIS 95

HUNER, N.P.A." ................................................. 58 LATTA, R.G ............. ........................ 47, 51, 66,77 HUNTER W ....... ...... ...... ...... ................. .... ......... l4 LAWTON-RAUH, A ......................................... 68 HUSBAND, B.C ................................................. 65 LEBLANC, S ............ ... ............. .............. .. .... ...... 54 HWANG, Y.T ..................................................... 50 LEE, D.R ...... ....... .................... ... .................. ....... 26 IGIC, B .......... .. ....... .... .............. ... .... ...... ..... ... 66, 79 LEFEBVRE , D.D ...................... ................... ..... 52 IRELAND, R.J ....... ... ...... ........ .................... ........ 51 LEFEBVRE, D.D ............................................ ... 22 IRELAND, R.J ...... .. ....... ... ..... ............ ..... ............ 39 LEGENDRE, P ...... ..... ..... ................ .. ............... 16 ISHII, I ........... ....... .... ...... ....... .... ... ... .................. .. 91 LESTER, G.E .............. .......... .... .. ............ .......... . 49 IVANOV, A.G .. .. .......... .. ... ....... .... .................. 7, 58 LEVIN, D.A ..................... ....... ......... .................. . 66 JACOBS, J ..... ... .... .... .......... ......... ....... ........ ....... .. 59 LEXER, C ............................................. .... ... 67, 78 JEONG,H.S.L .... ........ ....... ... .... ........... ................. 53 LI, C .................................................................... 69 JEUNE B ................... ..... ...... .. ... .... ......... ............. 40 LI, R . ... ... ... ....... ... ................. ... ........... ........ .. ....... 26 JOHANSEN, A.D ...... ........... ...................... ........ 51 LIEFFERS, V.J .................... ............. ... ........ ...... . 31 JOLY, S .............................. ................ .. ............... 34 LINSCOTT, T.M ......... ....... ................. ...... ........ . 81 JOLY, S . ............ ................... ......... .......... ............ 79 LISTON, A .... ............................. .................. ...... 86 JONES, D.A ........ .................. ....... ....... ...... .. ........ 35 LIVINGSTONE, K ........ .... .... ... .. ................... ..... 67 JOOST, S .... .... ...... .... ... ............ ............................ 51 MA, FENGSHAN ............................................... 27 JOSEPHSON, K ..... ............ ... ..... ......................... 39 MACDONALD, E .............................................. 27 KANE, N.C ................................ .. ....................... 78 MACDONALD, S.E ..................................... 20, 31 KARTESZ, J.T ................. ... ..... ............ ............... 3 MACFIE, S ................... ... .......................... ..... ... . 20 KA V, N.N.V •................................................ 46, 59 MACFIE, S.M ............... ... ......................... .......... 35 KAWAHARA, T ................................................. 91 MACKENZIE, T.D.B ............. ...................... 27, 44

KAY,K.M ................ .......... ................................. 79 MADILL, R.W ................................................... 19 KEEFE, A.P . ....................... .... ............... ............. 52 MAGILL, T ......................................................... 22

KELLOGG, C.D ................................................. 80 MALBOOBI, M.A ............................................. 22

KELLY, D.J.A .................................................... 52 MARIETTE, S .................................................... 69

KELI;-Y,H ......... .. ... ................. ...... ...................... 51 KEMP, J.F .... ........................ ........ ....... ... ............. 24

MARKHAM, J ........................ ............ ....... .. ....... 16 MASSICOTTE, H.B ............. ................. ....... ...... 43

KENKEL, N.C .... ....... ...... ........... ........... ....... 25, 28 MATTHES, U .................................... .. ..... .... ...... 23

KENKEL, N.C., ...... .... .......... .............................. 24 MA TTlllAS, L.A ... .......................... ........ ......... 28

KEPHART, S . .............. .... ...... ....... ...................... 90 MA TTOO, A.K ................................ .. .. ........ ..... . 53

KERMODE, A.R . ... .................... ........................ 15 MAUMONT, S .......... ........ ... .... ........ .... ........ .... .. 19

KING,J .............................. ................ .. ................ 26 MAUN,M.A ....................................................... 47

KLEE, H.J ........................................................... 42 MAXWELL, D ............. ......................... ... .......... 55

KOH,S .................................................................. 4 MAZEROLLE, D.M ..... ........... ..................... 29, 54

KOHALMI, S.E . .............. ... .... ............................ 48 McCOURT, P ................................... ........ ..... ..... 15

KOHN, J.R .................................................... 66, 79 McGINN, P.J ........... ........................................... 55

KOONJUL, P.K ......... ......................................... 25 MCGLAUGHLIN, M .......................... ............. .. 81

KOONJUL, P.K ............. .............. ................. 17, 24 MCINTYRE, L . ........ .......................................... 51

KOONTZ, J.A ............. .... .................................... 80 McKIM, S ................. ......... ..... ... ..................... 7, 28

KRAHULCOV A. A ........... ..... .... ....... ................. 77 KRAHULEC, F ................................................... 77 KRANNITZ P.G •........ ......................................... 3 KREMER, A ......................... ........................ 67, 69 KRESOVICH, S .................................................. 80 KRISHNA, P ....................................................... 38 KRISTIE ,D.N ..................................................... 53 KROL, M ....................................................... 11, 53 KUSAKINA, J .... ..... ........ ........... ............. ........... 53 LACROIX D ..... ....... .............. ..... ........................ 40 LACROIX, C.R .......... .. ........... .. .. ..... ..... .............. 24 LAGU, M.D ........... ... .... .............. ....... ........ ....... .. 74 LAITUNG, B ..... ........ ....... ................................... 54 LASTRA, R.L ........... ..... ... ........... ........ .............. . 25

MCMILLAN, E •.... .. .................................... ...... 35 MESS, J.-N ........................................ ................. 16 MEYER, R.L ...................................... ......... ....... 49 MILLER, A ........................ ............................. .... 38 MILLER, A.G ..................................................... 23 MILLOT, S .................. ........ ............... ................ 54 MINHAS, J.S ........................................ .............. 24 MISKIEWICZ, E ................................................ 53 MOLEN, T .......................................................... 55 MOORE,M .......... ... ............... .. ............ .... .. ......... 26 MORJAN, C.L ........ ............ .................. ...... ........ 82 MOURELLE, C ................................... .... ........... 27 MOXSOM, D.M .................... ....... ................. .... 29 MOYLE, L.C . .......... ................. ..... ................ ..... 82

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MULLEN, R. T ........ , .... ...... ... ..... ... ...... ... .... ........ 41 RAND, T ... .. ............... .. .... ... .. .. ............... ..... .... .... 10 MULLEN, R.T . .......................................... ... 39, 50 RAN1EKAR. P.K ...... .. .... .... ...... .. .. .. .... ... ........ .... 74 MULLIGAN, R. C . ...... ... ...... ... ...... ... .... .......... .... 29 RAUSCHER, J.T ....... .............. .. ........ ........... 63, 79 MULLIGAN, R.C ..................... ... ....................... 55 RA V ANEL, S ............ .. .......... ...... ....................... 12 MUNRO, K.D . .. ..... ..... ..... ....... ... ... ...... ... ... .. .. 49, 56 REEKIE, E . .. ...... .... ...... ......... .. ................... ......... 49 NAIR, P ......... .. .. ....... .. .... .... ...... ............. ........ ...... 82 REEKIE, E.G ...... ...................... .......................... 57 NAKAZA W A, M .......... .. ........... ..... .... ................ 91 REINHARD, A.E . ........ .... ...... .... .. ...................... 85 NEWELL, R .............. .... ..... .. .......... .. ...... ............. 49 RIDING, R.T ........................... .. .. ................. ...... 26 NGUYEN, S ....... ................................................. 30 RIESEBERG, L.H ............................ 67, 68, 78,82 NGUYEN, S ........ .... ... ................ .. .......... ... .......... l7 RISSLER, H.M ....................... .. .... .... .................. 58 NICHOLLS, WILF ....... ................ ......... .............. .4 ROBICHAUX, R.H ... .. ....................................... 68 NICHOLS, B ........... .. ................. .. ........ .... ... ........ 12 RODERMEL, S ......... .. .... ......................... .. .. ...... 58 NIKOLCHEV A, L.G ................ .... .. ..... ..... .. ........ 30 RODERMEL, S.R .... .... .. .......... ...... .............. .. ...... 6 NIYOGI, K.K .... .. .... ................ ........ .... ... ............. ll ROJE, S ............................................................... 32 NOEL,LJ . ..... ...... ...... .. .... .......... ........ ........ ........ 31 ROSS, A. R . .. .. ...... ..... .. ........ ... ............................ 15 NOLAND, M.H ....... .... .................. .. .................... 81 ROSSO,D ....... ........... ..... ......... .. ... ....... ......... ...... 58 NOSKO, P ............... ............. ............ ....... ...... 49, 52 ROUSSEL, G ... .......... ... ... ........ ......................... .. 67 NUNES,C ....... ... .... ... ..... .... .... .... .... ... ..... ............. 24 RUSSELL, 1 .................................................... .... 90 OHTSUKA, A ....................................... .. ............ 83 RUVINSKY, J.R . ......... ............ ...... .............. 42, 75 01EDA,F ............................ .................... ............ 83 RYSER, P . ..................... ...... ...... ............. 33, 45,60

OLIVIERI, A.M ........................ .. ........................ 88 SABARA, H ....................................................... 65 OQUISTI,G .......................................................... 7 SAINI H.S ........................................................... 17

OTFINOWSKI, R ............................................... 24 SAINI, H.S .................................................... 24, 25 PARISOD, C ....................................................... 51 SAINT AGNE, C ................................................. 69

PARKER, V.T ......................... ... ......... .. .............. 84 SANDERSON, M.J. ........................................... 69

PATTERSON, T.B .................. ......... ... ................ 64 SANE,P.V ........................................................... 7

PEREZ,R ................. ............................. .. ............ 84 SANG, T ............................................................. 69

PETERSON, A .......... .. ........... ....... .. .. .. ......... .... ... 84 SARCHFIELD, M . ............................................... 7

PETERSON, C. A ......... .. ......... .... .. ..... ...... .. .. .. .... 27 SARGENT, R.D ................................................. 86

PETERSON, C.A ................................................ 60 SASUCLARK, M ............................................... 89 PETERSON, 1 . .................................................... 84 SAUDER, W .................................................. ..... 33

PETIT, R.1 .................... .. ..................................... 67 SA VITCH, L.V ................................................... 11

PETTERSON, C.D ...................... ........................ 57 SAVITCH, L.V., ................................................. 48 PICKETT-HEAPS, 1.D ......................................... 9 SCHEIBLING, R.E ........................................ 4, 33

PIERCE, S ........................................................... 89 SCHEMSKE, D.W ....................................... 70, 74

PLANT, A.L ................................................. l4, 60 SCHENK, 1.1 . ..................................................... 86 PLAXTON, W.C ............................ ..................... 13 SCHIEFELBEIN, 1.W ........................................ 22

PLOMION, C .......................................... ............ 69 SCHMIDT, A.L ................................................. 33

POCOCK. T .......................................................... 7 SCHNEEWEISS, G.M ....................................... 87

POWELL, W ............... ... ..................................... 90 SCHUEGRAF, M ............................................... 33

PRICE, G.D ................ , ........................................ 55 SCHWARTZ, S.H .............................................. 56 PRICE, 1. ..................... .......................................... 7 SCOBELL, S ...................................................... 87 PUNTER, D ....................................... .. ................ 57 SCOTTI, I. .......................................................... 88 PURDY, B.G ......... ...... .. ... .......... .. ...... .. ... ... ......... 31 SEYMOUR, N ............................................. ....... 23 PURICH, M ................ ... .......... ..... ....................... 23 SHACHAR-HILL, Y ... ....................................... 32 PURUGGANAN, M.D .. ... ............ ..... ............ ..... 68 SHELP, B.1 . ... ................................... 13, 39, 45, 58 QIN, x ................................................................. 56 SHEORAN, I.S ...................................... ............. 24 QUESNELLE, P.E . .. .. ................ .... ..... .. ... ........... 31 SHERMAN-BROYLES, S.L. ............................ 79 QUINLIVAN, E ... .. .. .. ..... ............... ...... .. ... .... ...... 12 SHMIDA, A ... .... ........ .. .. ........... .......................... 85 QUINLIVAN, E.P ............................................... 32 SIMMONDS, 1 . .................................................. 48 RAGHOTHAMA, K.G ............ ..... .. ... ..... ............ 13 SLASKI, 1.1 . .............. .......... ............................... 11 RAJAKARUNA, N ..... ... ........... .... .. .................... 85 SLOGAN, 1 ......................................................... 24 RAJVEE, M.N ............. .. .... ... ... .. ... .. ..................... 32 SMISSEN, R.D ................................................... 88 RAMSEY, 1 ................. .... ................. .. ................. 70 SMITH, S.D ...... .... ................ .. ............. ....... ........ 88

ABSTRACTS 97

SMOL,1.P ............................................................. 9 V ANDERBELD, B ............................. ....... ........ 37 SNEDDEN, W.A ... ...... ... ................ ........... ... 15, 37 VASEY, M.C ....... ..... ..... ............ .................. .... .. . 84 SOEJIMA, A ............ .......... ............ ................ .. ... 91 VASSEUR, L ................................................ 29, 54 SOL TIS, D.E ..... ......... ....... .. .............. ....... ........... 71 VERGARA, 1.1 . .......................... : .......... ... .......... 83 SOLTIS, P.S ........................................................ 71 VERNESCU, C.I .... ... .. ............... ........ ........ ........ 60 SOUZA, V ..... ............... ....... ................................ 77 VIS CHI, M .......................................................... 88 SQUIRRELL, 1 . ......... .. ....................................... 90 WAHLERT, G . .............. ................. ........... ......... 84 SRIVASTAVA, 8 .. ........ ........ ............................. 59 WALLER, J.C ..................................................... 37 STARR, J.R ... .... ....... .. ...... ....... ............. ............ ... 34 WANG,Z ............................................................ 38 STAUDT, G ... ......... ... ... ............... .. ............. ........ 76 W ASTENEYS, G.O .. .................. ....... ..... .... ...... . 22 STOHLGREN, TJ ....................... ....................... 3 WATANABE, K ..... .... .. ........................ ....... ....... 91 STONE, 1.L ... ...... ..... ... .... ...... .. ... ............ .. ........... 89 WATERWAY, M ............................................... 34 STONE, S.L .......... ..... ....... .. ... .. ... ..... ...... ........... .. 47 WEBSTER, C.L .................................................... 3 STRAND,A ...................... ........... ......................... 6 WEGER. H.G ........ ..... ....... ... .. ............................ 57 STROTHER, 1.L ............ .... ...... ...................... .. ... 42 WELCH,C .......................................................... 60 SUBRAMANIAM, R .......................................... 16 WENDEL, 1. F ........................... ......................... 71 SUN,G .................................................. .............. 35 WHEELER, E.J. ........................................... 61, 89 SUTTON, 1 .......................................................... 59 WHITEHEAD 1

, C.L.. ............... .. ..... .... ............ : .. 20 SWEENEY, M.N ................................................ 35 WHm ALL, J.B ............... ....... ........... .. ............. 90 SWEETMAN, 1 ........ ....... ...... ................................ 9 WHITTON, J ........ ......... ................... 36, 71, 73, 85 SWEIGART, A.L ................................................ 89 WILCOX, M . ............. ...................................... ... 38 SYGUSCH, 1 ...................... ....... .......................... 16 WILEN, R.W .................................... .................. 12 TAKEMOTO, D .... .............................................. 35 WILLIAMS, J ..... .. ... .............. .... ......................... 23 TALENT, N ............................................ 17, 36, 73 WILLIS, 1.H ...................................... ...... 72, 81, 89 THEISS, K ............................ ............................... 90 WILSON, K.E ............................... ...................... 53 THOMAS, G ....................................................... 82 WOODHEAD, M ............................................... 90 THOMPSON, S.L. ........................................ 36, 73 WU,C.A ..... ..... ........ ................. .. ........................ 91 TILLEY, S .............. ................................. ... ......... 36 Y AHARA, T ..................................... 78, 83, 91, 92 TIRAJOH, A .................... ................ ...... ... ......... 60 YANG,J. .... ........ ......................................... .. ...... 15 TODD, C.D . ........................................................ 47 TOUDEHFALLAH, M ... ........................ .......... 14 TREBLE, R.G ......................................... ............ 51 TREMBLAY, E ............................................ 29, 54 TREMBLAY, L.J ................................................ 22 TROTTIER, G.C ................................................. 24 TRUESDELL, P.F .............................................. 22 TlJRELLI, M ......................................... .............. 82 TURNER. W ....................................................... 37 TYREE, M.T ...... ................... ................ ................ 1 VAN CAUWENBERGHE, O.R ............. .... .45, 58

YANG,1.Y .......................................................... 92 Y ASUMOTO, A ................................................. 92 YOUNG,H ........................... .............................. 92 YOUNG, L.W ............. .............. .......................... 12 ZAHARIA, I. ......................................... ............. 15 ZANETTO, A ..................................................... 69 ZHANG,Z ........... ... ........ ................. ................... 38 ZHOU, AILING ................................................. 69 ZIELINSKA, E ................................................... 41 ZIEMAK, M ....................................................... 12

98 Plant Canada 2003