Upload
kanes10
View
239
Download
2
Tags:
Embed Size (px)
Citation preview
Floral Color Changes in Boswellia sacra Flueck
Botany 2110 Samantha Kane
Flora-Morphology, Distribution, Functional Ecology of Plants Volume 206, Issue 9, September 2011
Facts about Boswellia sacra
Also known as Frankincense; found in the Bible
Part of the Burseraceae family
Used for perfume and medicine
Popular in trade
Facts about Boswellia sacra
Found in South Arabia and North East Asia
Found in extreme locations
Population is decreasing because of overgrazing and human destruction
National Park in Wadi Dowkha
Boswellia sacra
Flowering stage begins in the winter until April
Fruiting bodies are ripe by March
Characteristics: green calyx radial symmetry five white petals ten stamens that have yellow anthers one pistil nectariferous ring is present in the ovary and
can change colors from yellow to red to black
Purpose & Hypothesis
Purpose: to figure out why the nectariferous ring changed colors
Hypothesis: the color change helped lure pollinators towards the flower with the reward of nectar
The Study
Took place along the coasts of Dhofar and in the Wadi Dowkha National Park
Flowers were collected in February and March from 2006-2010
Nectar and pollination were observed in the morning (7:30-8am) and sunset (6-6:30) for a week
Microscopical observations were observed in labs in Florence
Under the Microscopes
Different stains were used to see detail under the light microscopes including:
Toluidine Blue for testing lignin
Mercuric Bromophenol Blue for proteins
Acriflavine stain for total polysaccharides
Alcian Blue for acidic polysaccharides
Fluorol Yellow-088 for lipids
Methods
The pistils and nectariferous discs were covered in glutaraldehyde (a disinfectant and preservative)
stained with PAS (Periodic Acid Schiff) to see undissolvable polysaccharides
stained with Blue Nile Sulfate to see the neutral and acidic lipids
The nectariferous rings were cut off and covered in an alkaline and an acidic solution to test for anthocyanins. (may appear in different colors depending on pH)
Results of Flower Organs
(Nectariferous Ring) Located between the stamens and the ovary (3mm in diameter)
Changes color from yellow to red depending on the maturity of the flower
Before anthesis, (flower opens its petals) the nectariferous ring is fully developed
Trichomes are covered in a cuticle layer where nectar drops can be found
The drops show a positive response to the PAS reagent, Alcian Blue, and Mercuric Mromopenol Blue. (shows polysaccharides exist!)
Stomata always open with guard cells appearing outward
Results of Flower Organs(Pistil)
The stigma (top of pistil) has a positive response towards the Alcain Blue, and Blue Nile Sulfate stains (test acidic polysaccharides and neutral lipids)
After fertilization, the ovary swells transforms into a fruit with a seed in each open compartment
Results of Flower Organs
(Anthers)Anthers on the flower are all the same size
with longitudinal dehiscence (spontaneously opening)
yellow in color with trichomes sparsely located
anthers swell due to the large amount of pollen
dehiscence takes place
Color Changes
The nectariferous ring is already a yellow color when the petals begin to open; many liquid drops found
Changes to orange and few drops are present. Nectar begins to be reabsorbed. Largest amount of pollen germination occurs. Anthers empty and the stigma changes its green color to a brown
Changes to red and is completely dry and lacking nectar. Anthers begin to fall and stigma dry up and darken
Only fifteen hours are needed for the color changes
Color Changes
Lastly, the nectariferous ring will turn brown with black patches. The surface is wilted and rough. The ovary is growing into the fruit
Takes two days to change from yellow to brown
Red stage changes to a green-blue color once dipped into an alkaline medium and will change back to red once rinsed in acid showing that there are many anthocyanins present.
Field Observations(Pollinators)
Many pollinators
Main pollinators in the day-bees, wasps, and ants
Other visitors-butterflies and little flies
pollinators preferred flowers with the yellow nectariferous ring , the red were not visited at all
Conclusions
Color changes help lead the pollinators towards the rewarding flowers
Mutualistic relationship (plants get pollinated and pollinator gets pollen and nectar as nutrients)
Insects are attracted to the yellow and orange phase; no nectar reward in the red phase
The color change occurs because of high amounts of anthocyanins
that flowers with nectar rewards and an attractive color for pollinators have a greater chance of reproducing and outcompeting other plants