Participation of phytohormones in the stomatal regulation of gas exchange during water stress

Almost all processes in the life of a plant are directly or indirectly affected by both stresses and phytohormones. Nevertheless, apart from abscisic acid, the role of phytohormones in plant response to water stress is far from being fully elucidated. This review tries to answer the question whether interactions between abscisic acid and some other phytohormones might be important in the regulation of stomatal opening during water stress and subsequent rehydration. Firstly, it describes the changes in the contents of individual endogenous phytohormones during water stress. Then, it deals with the effects of applied phytohormones on stomatal opening, and on transpiration and photosynthetic rates in different plants species. Finally, it focuses on the alleviation or stimulation of absicic acid-induced stomatal closure by application of other phytohormones.