chapter 7 bot3015l regulation of gas exchange of terrestrial plants presentation created by danielle...
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Chapter 7BOT3015L
Regulation of Gas Exchange of Terrestrial Plants
Presentation created by Danielle Sherdan
All photos from Raven et al. Biology of Plants except when otherwise noted
•Review photosynthesis and bulk transport in plants
•Observing leaf morphology
•Examples of highly modified leaves
•Leaf anatomy
•Stomata, adaptations to terrestrial environments
•Stomata aperture changes
•Further understanding of stomata by experimentation
Today
•Review photosynthesis and bulk transport in plants
•Observing leaf morphology
•Examples of highly modified leaves
•Leaf anatomy
•Stomata, adaptations to terrestrial environments
•Stomata aperture changes
•Further understanding of stomata by experimentation
The main ideas from last week’s look at the anatomy of the
angiosperm plant body
Photosynthesis primarily occurs in chloroplasts of leaves
Lilac (Syringa)
Review of photosynthesis
Note that this is a depiction with some gaps and misrepresentations for summary purposes
Triose phosphates
Transport Summary
A=absorption / assimilationL=loadingU=unloadingI=interchange
Today
•Review photosynthesis and bulk transport in plants
•Observing leaf morphology
•Examples of highly modified leaves
•Leaf anatomy
•Stomata, adaptations to terrestrial environments
•Stomata aperture changes
•Further understanding of stomata by experimentation
Leaf observationsWhat characteristics of leaves
make them well-adapted for their function?
Today
•Review photosynthesis and bulk transport in plants
•Observing leaf morphology
•Examples of highly modified leaves
•Leaf anatomy
•Stomata, adaptations to terrestrial environments
•Stomata aperture changes
•Further understanding of stomata by experimentation
Morphological AdaptationsResponses to Water Availability
Waterlily (Nymphaea)Note the misnomer, waterlilies are not in the Liliaceae family
Note the abundant of air spaces.
This plant grows in water.
Modified from Outlaw lecture
Morphological AdaptationsResponses to Water Availability
Note large volume-to-
surface area ratio ideal for dry
environment
Spines (modified
leaves) protect the water-filled
plant body from predation
Ferocactus
Example of turgor control of quick responses in highly specialized leaves
Photo by Jean Burns at Hosford bogPlants in motionVenus fly trap
Venus fly trap (Diaonaea)
Pitcher plant(Sarracenia)
Example of highly specialized leaves
Photos from www.serracenia.com
Today
•Review photosynthesis and bulk transport in plants
•Observing leaf morphology
•Examples of highly modified leaves
•Leaf anatomy
•Stomata, adaptations to terrestrial environments
•Stomata aperture changes
•Further understanding of stomata by experimentation
Lilac (Syringa)Cross-section, midvein of leaf
Three tissue systems in leaves too
Cross-section, blade of leaf
Lilac (Syringa)
Isolated epidermis stained with neutral red (vital stain that stains compartments of living cells)
Stomataadaptations to terrestrial environments
Today
•Review photosynthesis and bulk transport in plants
•Observing leaf morphology
•Examples of highly modified leaves
•Leaf anatomy
•Stomata, adaptations to terrestrial environments
•Stomata aperture changes
•Further understanding of stomata by experimentation
Stomata typical of dicots Stomata typical of monocots
Potato (Solanum) Maize (Zea)
Scanning electron microscope images
Scanning electron microscope image
Stomata and trichome of tobacco (Nicotiana)
Morphological AdaptationsResponses to Water Availability
Banksia
Note sunken stomata.
. . . Sunken stomata increase the distance from the moist leaf interior to the bulk atmosphere. Flux Equation!
Modified from Outlaw lecture
Oleander (Nerium)Trichomes and sunken stomata
Morphological AdaptationsResponses to Water Availability
Today
•Review photosynthesis and bulk transport in plants
•Observing leaf morphology
•Examples of highly modified leaves
•Leaf anatomy
•Stomata, adaptations to terrestrial environments
•Stomata aperture changes
•Further understanding of stomata by experimentation
Gas ExchangeOpen & Closed Stomata
Stomata animationModified from Outlaw lecture
Photos from Outlaw’s lab and also featured on the cover of the scientific
journal Archives of Biochemistry and Biophysics
Fava bean (Vicia)
Gas Exchange (g)Ion Transport—stomatal opening
Inside cell
Membrane
Proton extrusion makes membrane potential more negative and acidifies apoplast.
Water influx
Potassium uptake.
Thermodynamics: MP
Mechanism: MP & wall acidification activate the Kin channel
Modified from Outlaw WH, Jr. Integration of cellular and physiological functions of guard cells. CRC Crit Rev Plant Sci 22: 503-529
E. Water influx increases pressure, but water is incompressible, so guard-cell volume increases. The increase results from stretching of the dorsal wall.
A. Guard-cell symplast accumulate solutes from guard-cell apoplast.
C. Radial micellation of cellulose microfibrils prevents increase of cell diameter.
B. Water flows into guard cells osmotically.M
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BR
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D. Inner wall is strong and cannot be stretched.
Gas Exhange (e)Stomatal swelling
Modified from Outlaw lecture
Gas Exchange (j)Ion Transport—stomatal closing
Membrane
Inside cell
B. Potassium efflux.
Thermodynamics: MP
Mechanism: MP activates the Kout
channel
A. Anion efflux shifts the membrane potential to a less negative position.
Modified from Outlaw WH, Jr. Integration of cellular and physiological functions of guard cells. CRC Crit Rev Plant Sci
22: 503-529
ABA activates the Kout channel via cytosolic alkalinization.
Gas Exchangeion transport—ABA action
Membrane
Inside cell
ABA may be made in roots and transported to shoots, or made by leaves, or even by guard cells.
ABA activates the anion channel, directly or by several means indirectly (e.g., via Ca2+ signaling).
Modified from Outlaw WH, Jr. Integration of cellular and physiological functions of guard cells. CRC Crit Rev Plant Sci 22: 503-529
Today
•Review photosynthesis and bulk transport in plants
•Observing leaf morphology
•Examples of highly modified leaves
•Leaf anatomy
•Stomata, adaptations to terrestrial environments
•Stomata aperture changes
•Further understanding of stomata by experimentation
What internal and external factors likely affect stomatal aperture?
What are the effects of CO2 on stomatal aperture?
Why do we want to know? How is this important?
About 1700 gallons of water are required to grow food for one adult in the US per day!
(From 1993 National Geographic)
Experimental Design
The question: What are the effects of CO2 on stomatal aperture?
How can we manipulate CO2 concentration?
One way:CO2 + NaOH => NaHCO3 (sodium bicarbonate)
In notebook and checked before you leave
• Drawings
• Methods
• Data
• Review questions
QUIZ NEXT WEEK
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