24-Epibrassinolide-Mediated Mitigation of Cd-Induced Toxicity in Hyperaccumulator – Brassica juncea: Influence on Photosynthesis, Cell Death, Redox, and Elemental Status

Cadmium (Cd) is toxic to plants and other living beings present in the next trophic level. It inhibits growth of the plant. Since Brassica juncea is a hyperaccumulator plant for Cd, its consumption is hazardous to living beings. Hence, it is important to reduce the accumulation of Cd inside the foliage of mustard plants to make it safe for consumption and reduce bio-magnification. 24-Epibrassinolide (EBL) was applied in various doses (10^–10, 10^–8 or 10^–6 M) as a foliar spray at 25–30 days stage of growth on Brassica juncea var. Varuna, growing in Cd (25 or 50 mg Kg⁻¹ of soil) amended soil. The sampling was done at 45 and 60 days after sowing (DAS) to determine photosynthesis, nutrients, antioxidants, cell death, enzymatic activities, reactive oxygen species, carbohydrate, and Cd content. EBL restricted the Cd uptake and translocation of Cd from root to shoot and induced defence responses to protect photosynthetic machinery. Out of the three doses, EBL (10^–8 M) proved most effective and the effect was more pronounced against lower concentration (25 mg Kg⁻¹ soil) of Cd which persisted at both the stages of sampling. The study suggests that EBL alleviated the adverse effects generated by Cd on physiology of the plant.