1. 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

2. 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

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 Note that this is a depiction with some gaps and misrepresentations for summary purposes Triose phosphates

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 observations What 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 Adaptations Responses 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 Adaptations Responses 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 Photo by Jean Burns at Hosford bog Plants in motion Venus fly trap Venus fly trap (Diaonaea)

13. Pitcher plant (Sarracenia) Example of highly specialized leaves 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. Lilac (Syringa) Cross-section, midvein of leaf Three tissue systems in leaves too Cross-section, blade of leaf

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

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

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

20. Morphological Adaptations Responses 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. Oleander (Nerium) Trichomes and sunken stomata Morphological Adaptations Responses to Water Availability

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. Gas Exchange Open & Closed Stomata Stomata animation Modified 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)

24. 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 K in channel Modified from Outlaw WH, Jr. Integration of cellular and physiological functions of guard cells. CRC Crit Rev Plant Sci 22: 503-529

25. 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. MEMBRANE CELL WALL D. Inner wall is strong and cannot be stretched. Gas Exhange (e) Stomatal swelling Modified from Outlaw lecture

26. Gas Exchange (j) Ion Transport—stomatal closing Membrane Inside cell B. Potassium efflux. Thermodynamics: MP Mechanism: MP activates the K out 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

27. ABA activates the K out channel via cytosolic alkalinization. Gas Exchange ion 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 Ca 2+ signaling). 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 CO 2 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 CO 2 on stomatal aperture? How can we manipulate CO 2 concentration? One way: CO 2 + NaOH => NaHCO 3 (sodium bicarbonate)

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