Plant steroidal hormone epibrassinolide regulate – Heavy metal stress tolerance in Oryza sativa L. by modulating antioxidant defense expression

• Chromium treatment inhibited the growth and activation of antioxidative defense system in rice.
• Pre-soaking treatment of EBL to Cr treated rice seedlings, lowered metal uptake and stress indices significantly.
• Applications of EBL to stressed rice seedling strengthened defense system by up-regulating gene expression

The present research paper is aimed to study the effect of 24-epibrassinolide (EBL) on growth of seedling, metal uptake, stress markers, antioxidative enzyme activity and gene expression in chromium (Cr) stressed rice seedlings variety Ratna. The exogenous application of EBL caused a significant reduction in Cr accumulation and improved the growth of seedlings. However, the results also showed that antioxidative enzymes activity and mRNA expression of these genes (Mn-SOD, Cu/Zn-SOD, Cat A, Cat B, APX and GR) significantly increased in seedlings treated with Cr ions under the influence of EBL. Taken together, our results demonstrate that exogenous application of EBL is more effective to ameliorate the Cr metal stress by up-regulating the activity of antioxidative enzymes.