Evaluation of Brassinolide Effect on Growth, Proteins and Antioxidative Enzyme Activities in Brassica Juncea L.

The present study investigated the linkages between exogenous application of two commercially available brassinolides (24-epiBL and 28-homoBL) on total protein, carbohydrates and antioxidant enzyme system in Brassica juncea to elucidate the antioxidative protective mechanism. Seeds treated with different concentrations of 24-epiBL and 28-homoBL (lO^M, 10~^sM, and 10~¹⁰ M) exhibited better growth as compared to control seedlings. This improvement was observed more by 24-epiBL as compared to 28-homoBL in 20 days old seedlings. Enzymes involved in antioxidant defense system of the plant showed increasing trend with both brassinolides treatments but concentration dependent manner. Superoxide dismutase (SOD 1.15.1.1), ascorbate peroxidase (APOX EC: 1.11.1.11) and dehydroascorbate reductase (DHAR EC: 1.8.5.1) exhibited amelioration with 24-epiBL while catalase (CAT 1.11.1.6), polyphenol oxidase (PPO 1.14.18.1) and indole acetic acid oxidase (IAAO) showed increased activity level with 28-homoBL. However, treatment of seeds with different concentrations of both 24-epiBL and 28-homoBL helped in enhancing the growth, protein and various enzymatic activities involved in defense system operated in B. juncea. These results suggested that application of brassinolides may cause brassinosteroid induced elevation in defense system that enable the plant to behave better than control plants.