TY - JOUR
AU - Sharkey, Thomas D.
AB - Abstract Mild water stress, on the order of −1.0 megapascals xylem water potential, can reduce the rate of photosynthesis and eliminate the inhibition of photosynthesis caused by O2 in water-stress-sensitive plants such as Phaseolus vulgaris. To investigate the lack of O2 inhibition of photosynthesis, we measured stromal and cytosolic fructose-1,6-bisphosphatase, sucrose phosphate synthase, and partitioning of newly fixed carbon between starch and sucrose before, during, and after mild water stress. The extractable activity of the fructose bisphosphatases was unaffected by mild water stress. The extractable activity of SPS was inhibited by more than 60% in plants stressed to water potentials of −0.9 megapascals. Water stress caused a decline in the starch/sucrose partitioning ratio indicating that starch synthesis was inhibited more than sucrose synthesis. We conclude that the reduced rate of photosynthesis during water stress is caused by stomatal closure, and that the restriction of CO2 supply caused by stomatal closure leads to a reduction in the capacity for both starch and sucrose synthesis. This causes the reduced O2 inhibition and abrupt CO2 saturation of photosynthesis. 1 Research supported by U.S. Department of Energy contracts DE-FG08-84ER13234 and DE-FG08-87ER60568. This content is only available as a PDF. © 1989 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)
TI - Mild Water Stress of Phaseolus vulgaris Plants Leads to Reduced Starch Synthesis and Extractable Sucrose Phosphate Synthase Activity 
JF - Plant Physiology
DO - 10.1104/pp.89.4.1066
DA - 1989-04-01
UR - https://www.deepdyve.com/lp/oxford-university-press/mild-water-stress-of-phaseolus-vulgaris-plants-leads-to-reduced-starch-EusBUfU4Zx
SP - 1066
EP - 1070
VL - 89
IS - 4
DP - DeepDyve
ER -