Proline Metabolism and Growth of Brassica Juncea Seedlings under Water Deficit Stress

摘要

Growth characteristics, proline content and activities of pyrroline-5-carboxylate synthetase (P5CS) and proline oxidase (PO) were studied in the seedlings of four Brassica juncea cultivars differing in drought tolerance viz. Varuna (resistant), Prakash (moderately resistant), PPMS (sensitive) and SR-3 (salt-tolerant somaclone of Prakash). Under water deficit stress, drought tolerant cv Varuna showed maximum drought tolerance index of 0.68. In the seedling of this variety, proline content increased 18.2 and 23.6 folds in the presence of stress at the time of sowing and after 48h of sowing, respectively. Compared to respective controls, increase in proline biosynthetic enzyme (P5CS) was maximum in the cultivar SR-3 followed by Varuna and minimum in PPMS. Reduction in the activity of proline catabolizing enzyme PO was maximum in cv Varuna and minimum in cv Prakash subjected to stress during sowing and in cv PPMS stressed after 48 h of sowing.