Effect of osmotic stress on osmolyte accumulation and ammonia assimilating enzymes in chickpea cultivars

An investigation was conducted to evaluate the effect of osmotic stress on four chickpea cultivars, viz., two drought tolerant (ICC 4958 and Vijay), and two drought susceptible (JG-216 and PG 1808) subjected to mild (−0.4 MPa) and severe (−1.2 MPa) osmotic stress induced by PEG-6000. The activity of ammonia assimilation enzymes, viz., nitrate reductase (NR) glutamine synthetase (GS), glutamate synthase (GOGAT) decreased, while activity of proline synthesizing enzyme Δ1 pyrroline-5-carboxlate synthetase (P5CS), and contents of proline, glycine-betaine and mannitol increased significantly in both drought tolerant and susceptible chickpea cultivars under mild and severe osmotic stress conditions. The extent of increase was higher in tolerant than susceptible cultivars. ICC-4958 recorded higher accumulation of osmolytes, viz., proline, glycine-betaine, mannitol and P5CS activity with less decrease in the activity of NR, GS, and GOGAT.