Effect of PEG induced osmotic stress on osmolytes and antioxidative enzymes in sorghum seedlings

The present investigations were undertaken to evaluate the levels of proline and glycine betaine osmolytes and activities of antioxidative enzymes under PEG-6000-induced osmotic stress in drought susceptible, tolerant and stay-green sorghum genotypes. A total of forty-eight drought susceptible, tolerant and stay-green rabi sorghum genotypes were screened to evaluate proline and glycine betaine accumulation under osmotic stress of PEG-6000. Among the tolerant genotypes, RSLG-262 and RSV-1366 accumulated the highest proline content, whereas, RSV-458 and Hadgaon local accumulated the highest glycine betaine content than susceptible genotypes. The high proline accumulating tolerant genotypes, RSLG-262 and RSV-1366 also exhibited correspondingly the highest {increment}1_pyrroline-5-carboxylate synthetase activity. The mean activities of antioxidative enzymes such as superoxide dismutase, catalase, peroxidases and relative leaf water content were higher in the leaves of stay-green genotypes, followed by tolerant and susceptible types. Within stay-green genotypes, B-35 and E-36-1 and a drought tolerant genotype RSLG-262 recorded higher antioxidative enzyme activities as compared to other genotypes. The stay-green genotypes, B-35 and E-36-1 and a tolerant genotype RSLG-262 appeared to be the most promising ones. © 2014 Indian Society for Plant Physiology.