Osmolytes-antioxidant behaviour in Phaseolus vulgaris and Hordeum vulgare with brassinosteroid under salt stress

Abstract

The relationship between compatible solutes (osmolytes) and antioxidants are the strategies that plants have developed to tolerate salt stress. Pre-treatment of Phaseolus vulgaris L. cv. and Hordeum vulgare L. seedlings with brassinosteroids (BRs) could be enhance their tolerance to saline stress during germination. During the germination period, a considerable increase was observed in proline levels (up to 340%) in the seedlings subjected to saline stress (S), whereas in the BRS group, the proline increment was not significantly. Starting from the fourth day of germination, betaine levels in seedlings pretreated with brassinosteroids and then with water (BRW group) and in BRS showed a significant increase versus C and S seedlings, possibly because such a precursor promotes betaine biosynthesis. This could be responsible for the enhanced growth observed in BRS versus S seedlings, as well as for preventing the decrease in chlorophyll content in the BRS group. The accumulation of betaine seems to correlate with the greater tolerance of these seedlings against saline stress. A relationship between antioxidant glutathione and salt tolerance was observed in both plants, under the effect of brassinosteroid. An index of halophytism was proposed to express tolerances of Phaseolus vulgaris and Hordeum vulgare by brassinosteroid treatment. © 2006 Asian Network for Scientific Information.