Regulation of Photosynthetic Carbon Metabolism in Water-Stressed Sunflower
Water stress limits plant production in many parts of the world. When leaf mesophyll cells lose water and turgor their capacity for photosynthesis declines1,2 and the rate of photosynthesis per unit leaf area decreases. This is not caused by stomatal closure only, but by inhibition of metabolism1,2,3. The mechanisms by which cell water deficit affects metabolism and slows CO2 assimilation are not well understood4,5. Light harvesting and electron transport in thylakoid membranes are less sensitive to water stress than is photophosphorylation4,5,6, which takes place in the chloroplast stroma and may be affected by increased concentrations of stromal components. Without an understanding of the effects of water stress on the mechanisms of photosynthesis, selection of plants with characteristics better adapted to drought will be hindered, as will direct manipulation of the photosynthetic system.
KeywordsWater Stress Mesophyll Cell Leaf Water Potential Total Soluble Protein Energy Charge
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- 2.D. W. Lawlor, Water stress induced changes in photosynthesis, photorespiration, respiration and CO2 compensation concentration of wheat, Photosynthetica 10: 378 (1976).Google Scholar
- 5.D. W. Lawlor, Effects of water and heat stress on carbon metabolism of plants with C3 and C4 photosynthesis, in: “Stress Physiology in Crop Plants”, H. Mussell and R.C. Staples eds; Wiley Interscience, New York, (1979).Google Scholar
- 7.D. W. Lawlor and R. Khanna-Chopra, Regulation of photosynthesis during water stress, in: “Advances in Photosynthesis Research”, C. Sybesma, ed., Martinus Nijhoff/Dr W. Junk Publishers, The Hague (1984).Google Scholar
- 8.H. M. Younis, J. S. Boyer and Govindjee, Confirmation and activity of chloroplast coupling factor exposed to low chemical potential of water in cells, Biochim. Biophys. Acta 54: 328 (1979).Google Scholar
- 9.J. S. Boyer and H. M. Younis, Molecular aspects of photosynthesis at low leaf water potentials, in: “Effects of Stress on Photosynthesis”, R. Marcelle et al., ed., Martinus Nijhoff/Dr W. Junk Publishers, The Hague (1983).Google Scholar