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Plant volatiles: Plant volatiles: their importance in ecology and their importance in ecology and
atmosphere sciencesatmosphere sciences
Catherine Fernandez
Elena Ormeño Lafuente
DFCV Team
IMEP
OutlineOutline
Part I: biogenic volatile features1- What are plant volatiles ?2- Sources3- Types: examples of terpenoids and phenols4- Terpenoid precursors5- Plant volatiles as secondary metabolites
Part II: Functional levels of plant volatiles1- Plant 2- Ecosystem3- Atmosphere 4- Techniques used to study BVOC
OutlineOutline
Part I: biogenic volatile features1- What are plant volatiles ?2- Sources3- Types: examples of terpenoids and phenols4- Terpenoid precursors5- Plant volatiles as secondary metabolites
Part II: Functional levels of plant volatilesPart II: Functional levels of plant volatilesPart II: Functional levels of plant volatiles111--- Plant Plant Plant 222--- EcosystemEcosystemEcosystem333--- AtmosphereAtmosphereAtmosphere444--- Techniques used to study BVOC Techniques used to study BVOC Techniques used to study BVOC
11-- WhatWhat are plant volatiles ?are plant volatiles ?
Volatile organic compounds (VOC)
Biogenic (BVOC)
Anthropogenic (AVOC)
“Living plants”
Litter
Vegetation burning
Phytoplancton
Soil microorganisms
Small scale combustion
Mobile sources
Solvent use
Fossil fuel production and distribution
Chemical industry
Fossil fuel combustion
Molecules thermal energy
intermolecular attractions binding the molecules as liquid
Liquid → gas phase
11-- WhatWhat are are biogenicbiogenic VOC ?VOC ?
Low molecular weight Low boiling point
(e.g. isoprene: 34 oC)
Vapor pressure = atmospheric pressure
Low concentration of the volatiles in the atmosphere surrounding the plants
High vapor pressure (indicator of the volatility of a compound)
11-- WhatWhat are are biogenicbiogenic VOC ?VOC ?
Goldstein & Galbally 2007
Enviironmeme ntalSciiencece &
TechTech nology
5 10 15
22-- Source of Source of Biogenic VOC Biogenic VOC
Leaves, stems, flowers, fruits, trunk.
Transport of compoundsthrough the transpiration stream
Primary and secondary roots
Non-oxygenated=terpenes
Terpenoids
Oxygenated
Terpenoids
Most varied class of natural compounds (25,000)
Lipophilic properties
Mainly cyclic and unsaturated
The are classified according to the number of C atoms they have,which is multiple of 5
33-- Types of Biogenic VOC Types of Biogenic VOC
Alcohols, ketones, esters, aldehydes,
furanoids
Alkenes (terpenes)
Tiglic acid
Methylbutenol
Others: isoamyl alcohol, isovaleric acid, senecioicacid, ß-furoic acid,
Isoprene
(C5H8O2, acid)
(C5H8, alkene) (C5H10O, alcohol)
Hemiterpenoids → C5, only a few produced naturally
33-- Types of Biogenic VOC Types of Biogenic VOC
Terpenoids
Monoterpenoids → C10, thousands of different structures
α- pinene(alkene)
myrcene(alkene)
linalool(alcohols)
OH
Limonene(alkene)
camphor(ketone)
O
Linalool oxide(furanoid)
O
OH
Citronellal(aldehyde)
O
Methyl geranate(ester)
O
O
Terpenoids
33-- Types of Biogenic VOC Types of Biogenic VOC
Sesquiterpenoids → C15, most varied class of terpenoids
ß-caryophyllene(C15H24, alkene)
α-bergamotene
trans-nerolidol(C15H26O, alcohol)
dendrolasin(C15H22O, furanoid)
farnesene
Caryophyllene oxide (C15H24, alkene)
(C15H24, alkene)
HO
O
O
33--Types of Biogenic VOC Types of Biogenic VOC
Terpenoids
Terpenoids are isoprene units attached to one another by linking the head of one unit to the tail of another
head tail
the total number of double bonds, the position of the double bond in the final product the number of rings
Easy way to remember that terpenoidscontain a repetitive unit of 5 carbons that resembles isoprene
In reality, isoprene is not directly (or indirectly) involved in their synthesis, as it can not predict
Isoprene rule
Terpenoids ~ isoprenoids
33--Types of Biogenic VOC Types of Biogenic VOC
Biogenic (BVOC)1- 10 %
44--Terpenoid precursors Terpenoid precursors
Sesquiterpenoids
Hemiterpenoids
Monoterpenoids
44--Terpenoid precursors Terpenoid precursors
Emplacement: cytosol and plastids of mesophyl cells
Cytosol
Plastids
Emissions through cuticle and stomata
PLASTIDSCYTOSOL
IDPIsopentenyldiphosphate
DMAPPDimethylallylpyrophosphate
Pyruvate
MEP pathway Methylerythritol pathway
ISOPRENE (C5)
Geranyl diphosphate (C10)
MONOTERPENES (C10)
Pyruvate
MVA pathway Mevalonate pathway
IDPIsopentenyldiphosphate
DMAPP
44--Terpenoid precursors Terpenoid precursors
Actual precursors
Farnesyl diphosphate (C15)
SESQUITERPENES (C15)
+ IDPGeranyl diphosphate (C10)
Dimethylallylpyrophosphate
Secretory ducts
http://www.botany.hawaii.edu/faculty/Webb/BOT410/Secretion/secductpicea300.jpg
Emplacement: cytosol and plastids of secretorystructure cells
Thricome glands
Alfalfa
http://www.stonerforums.com/lounge/growfaq/1529_files/sp4r500w.jpg
http://www.nrc-cnrc.gc.ca/fra/education/biologie/galerie/trichome.html
Pinus sp.
44--Terpenoid precursors Terpenoid precursors
Emissions through secretory structure cuticle
55-- Biogenic VOC as secondary metabolitesBiogenic VOC as secondary metabolites
Secondary metabolites Up to the 1960s: waste products of primary metabolism
Primary metabolites Essential for life
Anabolic and catabolic processus necessary for plant respiration, growth, reproduction and nutrition
Secondary metabolites
Anabolic and catabolic processusnecessary for plant respiration, growth, reproduction and nutrition
Up to the 1960s: waste products of primary metabolism
Primary metabolites Essential for life
Non ubiquitous within the plant
Non universal
Difficulties in establishing their function
55-- Biogenic VOC as secondary metabolitesBiogenic VOC as secondary metabolites
Secondary metabolites Primary metabolites
Sugars, Amino acid Tricarboxilic acid Proteins Enzymes Nucleic acids Energy sources
Glycolisis Krebs cycle Photosynthesis and associated pathways
Carbon-based compounds
N-and S-based compounds
Terpenoids Benzenoids Fatty acid derivates
Carbon Hydrogen Oxygen
shikimate
pyruvate
Shikimate acid pathway
Mevalonate pathway (MVA)
Methylerythritol pathway (MEP)
Met
abol
ic P
roce
ssM
olec
ule
type
55-- Biogenic VOC as secondary metabolitesBiogenic VOC as secondary metabolites
OutlineOutline
Part I: biogenic volatile featuresPart I: biogenic volatile featuresPart I: biogenic volatile featuresWhat are plant volatiles ?What are plant volatiles ?What are plant volatiles ?Sources of plant volatilesSources of plant volatilesSources of plant volatilesTypes: examples of Types: examples of Types: examples of terpenoidsterpenoidsterpenoids and phenolsand phenolsand phenolsPlant volatiles as secondary metabolitesPlant volatiles as secondary metabolitesPlant volatiles as secondary metabolites
Part II: Functional levels of plant volatilesPlant EcosystemAtmosphere Techniques used to study BVOC
Ecosystem
Part IIPart II-- Functional levels of Biogenic VOC Functional levels of Biogenic VOC
O
Atmosphere
+O3, NO3, OH
Key component in the biosphere-atmosphere interactions.
Affect other plants and organism
Favour the ecosystem perturbation
Plant Play an additional or alternative role in plant defences
Part IIPart II-- Functional levels of Biogenic VOC Functional levels of Biogenic VOC
Constitutive plant volatiles:
Induced plant volatiles
Produced only under stress conditions, de novo synthesized,
Phyto-alexines (plant pathology)
11-- Biogenic VOC as protective compoundsBiogenic VOC as protective compounds
HO
Produced permanently by the plant,
Phyto-anticipines
Protection of the plant against:
High light
High temperatures
Soil salinity
Water deficit
Air pollution
Cold stress
Vickers et al. (2009)Nature Chemical Biology
11-- Biogenic VOC as protective compounds Biogenic VOC as protective compounds
Biotic stress: Mechanical damage due to herbivores
Pathogens infection
Photo-, thermo- and oxido-protectors
Plant volatiles: indicators of the chance of a plant to survive in the ecosystem
High light
High temperatures
Soil salinity
Water deficit
Air pollution
Biotic stress: Mechanical damage due to herbivores
Pathogens infection
Cold stress
trigger
generate
Biosynthetic pathways
Defensemetabolites
ROS production
Protection of the plant against:
11-- Biogenic VOC as protective compounds Biogenic VOC as protective compounds
0
50
100
150
200
250
300
350
400
25 30 35 40 45 50 55Temperature (oC)
Em
issi
ons
(nm
ol.m
-2.s
-1)
Monoterpene emissions of non-storing species increase with Temperature because:
Defense against high temperatures ?
11-- Biogenic VOC as protective compoundsBiogenic VOC as protective compounds
Monoterpenes/isoprene in non-storing species
their volatilization from intercellular spaces is favored Monson et al., 1992, Kesselmeier and Staud., 2000, Guenther et al 1995,
0
50
100
150
200
250
300
350
400
25 30 35 40 45 50 550
50
100
150
200
250
300
350
400
Temperature (oC)
(pmol.m
in-1.m
g-1protein)
Enzym
atic activity
Em
issi
ons
(nm
ol.m
-2.s
-1)
Defense against high temperatures ?
11-- Biogenic VOC as protective compoundsBiogenic VOC as protective compounds
Enzymatic activity
Monoterpene emissions of non-storing species increase with Temperature because:
their volatilization from intercellular spaces is favored
Monoterpenes/isoprene in non-storing species
the enzymatic activity is favored
Monson et al., 1992, Kesselmeier and Staud., 2000, Guenther et al 1995,
0
50
100
150
200
250
300
350
400
25 30 35 40 45 50 550
50
100
150
200
250
300
350
400
Temperature (oC)
(pmol.m
in-1.m
g-1protein)
Enzym
atic activity
Em
issi
ons
(nm
ol.m
-2.s
-1)
11-- Biogenic VOC as protective compoundsBiogenic VOC as protective compounds
Defense against high temperatures ?
Monoterpene emissions of storing species
Monoterpene emissions of storing species still continue under very high temperatures as they evaporate from the leaf reservoires
Monoterpenes/isoprene in non-storing species
Monson et al., 1992, Kesselmeier and Staud., 2000, Guenther et al 1995,
-20
0
20
40
60
80
100
120
25 30 35 40 45 50
% P
hoto
synt
hesi
s
Temperature
((Delfine et al. 2002, New Phytol)
Cork Oak (Quercus suber)
Defense against temperature ?
11-- Biogenic VOC as protective compoundsBiogenic VOC as protective compounds
Monoterpene-fumigated plants
Ambient air-fumigated plants
After fumigation with monoterpenes
Photosynthes is less inhibited by the temperature ramp than
in non-fumigated leaves
Monoterpenes: protection against
excess heat
Photo-, thermo- and oxido-protectors
Plant volatiles: indicators of the chance of a plant to survive in the ecosystem
High light
High temperatures
Soil salinity
Water deficit
Air pollution
Biotic stress: Mechanical damage due to herbivores
Pathogens infection
Cold stress
trigger
generate
Biosynthetic pathways
Defensemetabolites
ROS production
Protection of the plant against:
11-- Biogenic VOC as protective compounds Biogenic VOC as protective compounds
Storage of toxic compounds in secretory structures
Defense against biotic damage
Secretory ducts
Alfalfa
Glandular thricome
11-- Biogenic VOC as protective compoundsBiogenic VOC as protective compounds
Storage of toxic compounds in secretoy structures
Defense against biotic damage
Secretory ducts
Alfalfa
Glandular thricome
11-- Biogenic VOC as protective compoundsBiogenic VOC as protective compounds
entrap organisms (Eisner et al 1998, PNAS)
decrease the radiation absorbance and heat load over leaf surface (Gonzalez et al., 2008)
Chemical defenses
Physical defenses:
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
11-- Biogenic VOC as protective compoundsBiogenic VOC as protective compounds
Plant that is locally damaged by a herbivore emits inducedvolatiles systemically, both above- and belowground. Theseplant volatilescan affect various community members that eachexert different selection pressures on the plant.
22-- Biogenic VOC in the ecosystemBiogenic VOC in the ecosystem
Exudation from roots
Reach other plants which will experience changes in their growth, distribution andreproduction
Produced by the plant and liberated to the host environment (atmosphere, soil) in important concentrations
Changes experienced can be negative (inhibition of germination: autotoxicity) or positive
Released from decomposing litter (leves, fruits, twigs)
Terpenoids as allelochemicals (allelopathy)Volatilisation from
leavesLeaching from leaves
by rain, fog or dew
BVOCs can act as neighbour detection signals
Competition impacts on BVOC emissions thus constituting a platform for plant–plant interactions.
Some are produced for easily appreciated reasons:
Most of the time the functional compound can not be identified because:
toxic and deterrents for organisms attractants of organisms
VOC-mixtures rather than single compounds are functional Variability of emissions with environmental conditions
Biogenic VOC : functions difficult to establishBiogenic VOC : functions difficult to establish
Plant volatiles
LightTemperatureNutrientsDrought
Biotic factors
AgeCompetitionAbiotic
factors
Environmental effect on BVOCs
Biogenic VOC : functions difficult to establishBiogenic VOC : functions difficult to establish
Plant flammabilityPlant flammability
FIREFUEL
IGNITION AND HEAT SOURCE
BVOC
(O2, O3, NO2 …)
OXYDIZERS
33-- Biogenic VOC in the ecosystemBiogenic VOC in the ecosystem
Low LFL (Lower Flammability Limit) At relatively low concentrations, the flammable substance can produce fire or explosion, when an ignition source is present
Low flash point At a relatively low temperature, the flammable liquid forms an ignitable mixture in air
-pinene : 38 °C
camphene : 36 °C
ß-pinene : 36 – 39 °C
ß-myrcene : 40 – 43 °C
ß-caryophyllene : 205 °C
33-- Biogenic VOC in the ecosystemBiogenic VOC in the ecosystem
Plant flammabilityPlant flammability
33-- Biogenic VOC in the ecosystemBiogenic VOC in the ecosystem
Litter flammability Litter flammability increases with terpene content
Ormeno el., 2009 Forest Ecology and Management
Pinus Pinus sp. sp. CistusCistus sp. sp.
Ston
e pine
Maritim
e pin
e
Alep
po
pine
Rock r
ose
Crimso
n spo
t
rockro
se
Laure
l Roc
krose
Leaf terpenecontent
Ignition delay, flame height, flame residence time, burned biomass, combustion time
Flammability
BVOC modeling:essential for understanding regional
and global atmospheric chemistry
consequently
BVOCBVOC
O3
participate
Aerosol
NOx
Health Climate change Photochemistry
44-- Biogenic VOC in the atmosphereBiogenic VOC in the atmosphere
Emission rates of species
Abiotic factors
Plant emissions: indicators of the potential implication of a plant to the be involved in air pollution
L, T, seasonality
Importance of Biogenic VOC at global scale Importance of Biogenic VOC at global scale
(millions tons.year-1)
CH4
350 350
(Keppler, et al. 2006, Nature)
120120CH4
25 25
CH4
(Kirschbaumet al. 2006 Funct Plant
Biol)
11501150
Guenther et al. 1995,
Zimmerman, 1992
BVOCs
44-- Biogenic VOC in the atmosphereBiogenic VOC in the atmosphere
Stern and Kaufmann.
1996
500500
isoprene
100100
AVOCs
Lerdau 2008 science
BVOC BVOC reactivityreactivity Teflon, glass Air chamber renewalwith « clean air »
DifferencesDifferences insideinside & & outsideoutside thethe cuvette cuvette T, L, inside and outside Plant physiology inside
MechanicalMechanical stress stress duringduringenclosureenclosurePlant adaptation to theenclosure for 1 day beforesampling
Branch enclosure chamber
44-- Techniques used to study BVOC emissionsTechniques used to study BVOC emissions
Sampling methodology Sampling methodology
GC/MS-FID – for BVOC sampling in situ Provides more specific measurements for a broad range of VOCs with hourly quantification
3
PTR-MS - for direct analysis of BVOC in situ
Measures highly volatile compounds and allows fast response quantification, but is does not completely speciate all BVOC
2
GC/MS –for analysis of BVOC collected in adsorbent cartridgesAllows analysis of sticky and reactive compounds that may not be detected with in situ systems due to sample handling1
44-- Techniques used to study BVOC emissionsTechniques used to study BVOC emissions
Sampling and analysis Sampling and analysis methodology methodology
Biogenic volatiles: multidisciplinary studies Biogenic volatiles: multidisciplinary studies
Fall lab and wound VOC:http://www.colorado.edu/chemistry/falllab/index.htmMETHANE:http://sciencenow.sciencemag.org/cgi/content/full/2009/11Fisher et al 1994Mettre une diapo en plus sur: methane emissions and Me
jasmonate or other hormones
TerpenoidsTerpenoids as photoas photo-- and and thermoprotectorsthermoprotectors ??
400 800 1200 1600 2000
0
1
2
3
4
0 10 20 30 40 50
1.5
0
1.0
0.5
0.0
What are plant volatiles ? What are plant volatiles ?
Low molecular weight & vapor pressure
Terpenoids Hemiterpenes Monoterpenoids Sesquiterpenoids Diterpenoids
Benzenoids Phenylpropanoids Phenols (= phenolics)
N- and S containing compounds (C + H + N/S)
Carbon-based compounds (C + H)
Fatty acid derivates
Source Source ofof volatiles in volatiles in thethe plantplant
Cell wall↓
Pectin deposition
Flowers↓
Floral scents
Cell membrane↓
Fatty acid peroxidation
Chloroplasts
Cytosol
Many tissues↓
Phytohormone
Oxygenated C5 – C6
Fatty acid derivates
Benzenoids100s VOC
Methanol
Ethanol
Secretorycavities
HemiterpenesMonoterpenes
Sesquiterpenes
MonoterpenesSesquiterpenes
Stems, leaves, roots
C1-C3 (formic acid, acetaldehyde)
33-- Types of Biogenic VOC Types of Biogenic VOC
Carbon-based compounds
Terpenoids
Phenols
Fatty acid derivates
N-based compounds (alkaloids)
S-based compounds
Carbon Hydrogen Oxygen
Their production and emission
can be constitutiveconstitutive (e.g., in response to abiotic drivers such as light or temperature) or
inducedinduced (e.g., in response to stress such as wounding)
55-- Biogenic VOC as secondary metabolitesBiogenic VOC as secondary metabolites
Defense against biotic damage
herbivore
carnivore
Deterring
11-- Biogenic VOC as protective compoundsBiogenic VOC as protective compounds
or attractant compounds
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
TerpenoidsTerpenoids over the seasonal cycle over the seasonal cycle
●
Natural water supply (control)
Water availability reduced (test )
Staudt et al 2002 J Geophys Res-Atmos
Kermes oak (Quercus ilex L.)
Can plants release CHCan plants release CH44 ??
Beech (Fagus sylvatica)(Keppler, et al. 2006, Nature)
Plants release CH4 emissions
Zea mays (Beerling et al. 2008)
Plant do not release CH4 emissions !!
CH4 emissions of land plants (living and dead) are 30% of the present
evaluated global sources
rather 6%(Kirschbaum et al. 2006
Funct Plant Biol)
Isop
rene
em
issi
on ra
te(n
mol
es.m
-2.s
-1)
Photon flux(µmol.m-2.s-1)
Temperature (ºC)
Emissions increase with Emissions increase with Temperature because their Temperature because their volatilization is favored volatilization is favored
Emissions increase with light Emissions increase with light because their synthesis is because their synthesis is dependent on photosynthesis dependent on photosynthesis
Isoprene Monoterpenesin storing species
Monoterpenesin storing species
Defense against high temperatures ?
11-- Biogenic VOC as protective compoundsBiogenic VOC as protective compounds
Monoterpenesin storing species
Mon
oter
pene
emis
sion
rate
(nm
oles
.m-2
.s-1)
Indirect/delayed effect: Degradation via biotic & abiotic factors:
Atmosphere: wind, soil temperatures Soil: enzymes, clay minerals
Tritrophic relationships
Direct/rapid effect: Residence time Bioactive concentration Bitrophic relationships
33-- Biogenic VOC in the ecosystemBiogenic VOC in the ecosystem
TerpenoidsTerpenoids as as allelochemicalsallelochemicals ((allelopathyallelopathy))
Only litter of P. pinaster and P. halepensis burn when fire is set
P. pinaster litter
100 cm
PinusPinus burning (burning (Combustibility Table)
P. pinea litter
Litter of P. pinea is the only Pinus litter where fire is self-extinguishedafter some cm
PinusPinus burning (burning (Combustibility Table)
Litter of P. pinea is the only Pinus litter where fire is self-extinguishedafter some cm
P. pinea litter
PinusPinus burning (burning (Combustibility Table)
Vitreous fused silica disk
Temperature of 420°C
LitterLitter burning (burning (epirradiatorepirradiator technique) technique)
No wind and environmental temperature
Flame intensity
1
2
3
4
5
FIFI Flame height (cm)< 1
1-3
4-7
8-12
> 12
LitterLitter burning (burning (epirradiatorepirradiator technique) technique)
Ignition time
Time that litter takes to generate a flame
LitterLitter burning (burning (epirradiatorepirradiator technique) technique)
Combustion time
Time that litter (fuel) takes to burn, once the flame has appeared
LitterLitter burning (burning (epirradiatorepirradiator technique) technique)
33-- Types of Biogenic VOC Types of Biogenic VOC
Phenols (= phenolics)
Aromatic compounds
CH3Phenol Methyl phenol
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