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Chapter 7 BOT3015L Regulation of Gas Exchange of Terrestrial Plants

Chapter 7 BOT3015L 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. Today. Review photosynthesis and bulk transport in plants Observing leaf morphology

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Chapter 7 BOT3015L Regulation of Gas Exchange of Terrestrial Plants

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  1. Chapter 7BOT3015LRegulation of Gas Exchange of Terrestrial Plants Presentation created by Danielle Sherdan All photos from Raven et al.Biology of Plants except when otherwise noted

  2. 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 • 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

  3. The main ideas from last week’s look at the anatomy of the angiosperm plant body

  4. Photosynthesis primarily occurs in chloroplasts of leaves Lilac (Syringa)

  5. Review of photosynthesis Triose phosphates Note that this is a depiction with some gaps and misrepresentations for summary purposes

  6. Transport Summary A=absorption / assimilation L=loading U=unloading I=interchange

  7. 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

  8. Leaf observationsWhat characteristics of leaves make them well-adapted for their function?

  9. 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

  10. 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

  11. 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

  12. Example of turgor control of quick responses in highly specialized leaves Venus fly trap (Diaonaea) Plants in motion Venus fly trap Photo by Jean Burns at Hosford bog

  13. Example of highly specialized leaves Pitcher plant(Sarracenia) Photos from www.serracenia.com

  14. 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

  15. Three tissue systems in leaves too Cross-section, midvein of leaf Cross-section, blade of leaf Lilac (Syringa)

  16. Stomataadaptations to terrestrial environments Isolated epidermis stained with neutral red (vital stain that stains compartments of living cells) Lilac (Syringa)

  17. 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

  18. Stomata typical of monocots Stomata typical of dicots Potato (Solanum) Maize (Zea) Scanning electron microscope images

  19. Stomata and trichome of tobacco (Nicotiana) Scanning electron microscope image

  20. 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

  21. Morphological AdaptationsResponses to Water Availability Trichomes and sunken stomata Oleander (Nerium)

  22. 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

  23. Photos from Outlaw’s lab and also featured on the cover of the scientific journal Archives of Biochemistry and Biophysics Gas ExchangeOpen & Closed Stomata Fava bean (Vicia) Stomata animation Modified from Outlaw lecture

  24. Proton extrusion makes membrane potential more negative and acidifies apoplast. Water influx Potassium uptake. Thermodynamics: MP Mechanism: MP & wall acidification activate the Kin channel Gas Exchange (g)Ion Transport—stomatal opening Inside cell Membrane Modified from Outlaw WH, Jr. Integration of cellular and physiological functions of guard cells. CRC Crit Rev Plant Sci 22: 503-529

  25. A. Guard-cell symplast accumulate solutes from guard-cell apoplast. MEMBRANE B. Water flows into guard cells osmotically. C. Radial micellation of cellulose microfibrils prevents increase of cell diameter. E. Water influx increases pressure, but water is incompressible, so guard-cell volume increases. The increase results from stretching of the dorsal wall. CELL WALL D. Inner wall is strong and cannot be stretched. Gas Exhange (e)Stomatal swelling Modified from Outlaw lecture

  26. A. Anion efflux shifts the membrane potential to a less negative position. Inside cell B. Potassium efflux. Thermodynamics: MP Mechanism: MP activates the Kout channel Membrane Gas Exchange (j)Ion Transport—stomatal closing Modified from Outlaw WH, Jr. Integration of cellular and physiological functions of guard cells. CRC Crit Rev Plant Sci 22: 503-529

  27. Inside cell Membrane Gas Exchangeion transport—ABA action 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). ABA activates the Kout channel via cytosolic alkalinization. Modified from Outlaw WH, Jr. Integration of cellular and physiological functions of guard cells. CRC Crit Rev Plant Sci 22: 503-529

  28. 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

  29. 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)

  30. 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)

  31. In notebook and checked before you leave • Drawings • Methods • Data • Review questions QUIZ NEXT WEEK

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