Exogenous application of brassinosteroid alleviates drought-induced oxidative stress in Lycopersicon esculentum L.

摘要

Drought stress is considered as a restricting factor for plant products. Therefore, many compounds have been applied to minimize the harmful effects of stress. Brassinosteroid is one of the compounds with antioxidative characteristics. In this experiment, when the fourth leaf of tomato plants appeared, 24-epibrassinolide was sprayed to the leaves at 0.01 and 1 micro M concentrations for 3 days with one day interval. Then three levels of drought stress (control, 3 and 5 days withholding water) were applied. Thereafter, the interaction effects of 24-brassinosteroid (BR₂₇) and water stress on some biochemical and antioxidative parameters of tomato plants were investigated. Peroxidation of lipids and H₂O₂ content were reduced in the plants which were treated with BR₂₇. The intensity of some bands of stress enzymes (GPOD and APX) in the electrophoretic pattern was different in stressed plants treated with 24-epibrassinolide when compared with the plants under drought stress. An increase in the activity of antioxidant enzymes (POD, SOD, CAT, APX) and antioxidative compounds content including ascorbate, carotenoids and proline was observed in drought stress plants after pretreatment with BR. Based on our observations that pretreatment with 24-epibrassinolide caused a decrease in MDA together with an increase in antioxidant enzymes, it is likely that BR mitigated damage caused by water stress.