Analysis of proline metabolic enzymes in Oryza sativa under NaCl stress.

The regulation of proline accumulation in seedlings of rice (Oryza sativa L. cv. Badami) was investigated. The increasing concentration of NaCl from 0.5 to 2.5% progressively increased the proline content in rice. Proline accumulation caused by NaCl was related to protein proteolysis, an increase in OAT, P5CS, PSCR activity, a decrease in PDH activity. The maximum increase in proline content was recorded at 2.5% NaCl concentration as compared to control and other concentrations of NaCl. The highest significant activity of proline synthesizing enzymes, Delta1-Pyrrolline-5-carboxylate synthetase, Delta1-Pyrrolline-5-carboxylate reductase and Ornithine-delta-aminotransferase with a lowest activity of proline hydrolysis enzymes; Proline dehydrogenase were also recorded at 2.5% salinity over control and other concentrations of NaCl with a in-significant increase in the activity of Delta1-Pyrrolline-5-carboxylate synthetase and Ornithine-delta-aminotransferase at 0.5 % concentration of NaCl over control. Externally the addition of 300mg MnCl2, 220 ml(-1) 1/2 strength Hoagland solution, having 1% NaCl, was seen to increase a 893.9% in proline content of this variety as compared to control.