Mechanisms underlying plant tolerance to abiotic stresses

During the course of their life cycle, land plants are exposed to numerous abiotic stresses such as drought, salinity, low and high temperatures, high light, and UV irradiation. It has been estimated that, due to abiotic stress, the yield of fieldgrown crops in the United States is only 22% of their genetic potential yield (Boyer, 1982). While all of these environmental factors can substantially reduce crop yield, drought, salinity, and lowtemperature have been especially problematic for agricultural productivity (Thomashow, 1999; Hasegawa et al., 2000; Shinozaki and Yamaguchi-Shinozaki, 2000; Zhu, 2002). As a result, much research has been performed to understand the physiological mechanisms underlying the ability of plants to tolerate these stresses.