ABSTRACT
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, P5CR 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, D1-Pyrrolline-5-carboxylate synthetase, D1-Pyrrolline-5-carboxylate reductase and Ornithine-d-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 D1-Pyrrolline-5-carboxylate synthetase and Ornithine-d-aminotransferase at 0.5 % concentration of NaCl over control. Externally the addition of 300mg MnCl2, 220 ml-1 ½ strength Hoagland solution, having 1% NaCl, was seen to increase a 893.9 % in proline content of this variety as compared to control.