Moisture stress induced increases in the activity of enzymes of osmolytes biosynthesis are associated with stress tolerance in wheat genotypes

Abstract

Moisture stress is one of the most important factors limiting the survival and growth of plants in semi arid tropics. Osmotic adjustment is an important adaptive response to moisture stress in wheat (Triticum aestivum L.). The objective of this study was to determine the relationships between osmolyte accumulation, activity of enzymes involved in osmolyte biosynthesis with moisture stress tolerance in different wheat genotypes. An experiment was conducted to study the role of osmolytes in imparting moisture stress tolerance in five selected wheat genotypes, two tolerant and three susceptible. Contents of proline, glycine betaine and trehalose accumulated in all the genotypes under moisture stress in comparison to control. Moisture stress tolerant genotypes like C 306 and HD 2987 maintained higher level of these osmolytes in comparison to susceptible genotypes HD 2733, PBW 343 and HD 2967 under moisture stress condition. Studies on the activities of enzymes involved in osmolyte biosynthesis showed that comparatively greater increases in the activity of trehalose-6-phosphate synthase, betaine aldehyde dehydrogenase and pyrroline-5-carboxylate synthetase under moisture stress lead to increased biosynthesis of various osmolytes in tolerant genotypes C 306 and HD 2987, which ultimately resulted in improved moisture stress tolerance as compared to susceptible genotypes HD 2733, PBW 343 and HD 2967.