Authors who contributed equally to this work.
Decreased Rubisco activity during water stress is not induced by decreased relative water content but related to conditions of low stomatal conductance and chloroplast CO2 concentration
Article first published online: 16 JUN 2006
Volume 172, Issue 1, pages 73–82, October 2006
How to Cite
Flexas, J., Ribas-Carbó, M., Bota, J., Galmés, J., Henkle, M., Martínez-Cañellas, S. and Medrano, H. (2006), Decreased Rubisco activity during water stress is not induced by decreased relative water content but related to conditions of low stomatal conductance and chloroplast CO2 concentration. New Phytologist, 172: 73–82. doi: 10.1111/j.1469-8137.2006.01794.x
- Issue published online: 16 JUN 2006
- Article first published online: 16 JUN 2006
- Received: 20 February 2006 Accepted: 23 April 2006
- abscisic acid (ABA);
- relative water content (RWC);
- Rubisco activity;
- stomatal conductance;
- water stress
- • Rubisco activity decreases under water stress, for reasons as yet unclear. Here, the covariation of stomatal conductance (gs) and relative water content (RWC), often observed during water stress, was impaired to assess the separate effects of these factors on Rubisco activity.
- • Three different treatments were applied to soybean (Glycine max) and tobacco (Nicotiana tabacum): leaf desiccation (LD), in which stomatal closure was accompanied by large decreases of RWC; water stress (WS), in which minor decreases of RWC were observed along with stomatal closure; and exogenous application of abscisic acid (ABA), which triggered stomatal closure without changing RWC.
- • Decreased RWC did not induce decreased initial Rubisco activity, which was impaired only in soybean by 40% when the gs dropped below 50 mmol m−2 s−1, regardless of the treatment. The mechanism for decreased activity differed among treatments, owing to decreased activation in LD and to total activity and protein content in WS and ABA.
- • Despite the occurrence of Rubisco regulation, CO2 availability in the chloroplast, not impairment of Rubisco activity, limits photosynthesis during WS.