Brassinosteroids Reciprocates Heavy Metals Induced Oxidative Stress in Radish by Regulating the Expression of Key Antioxidant Enzyme Genes

ABSTRACT Heavy metal toxicity in plants lead to accumulation of reactive oxygen species (ROS). Antioxidant enzyme system is also not able to revert altered ROS homeostasis. The present study reports the heavy metal induced ROS toxicity by up-regulating the expression of key antioxidant enzyme genes through Brassinosteroids pre-soaking treatment in radish.

Regulation of growth and antioxidant enzyme activities by 28-homobrassinolide in seedlings of Raphanus sativus L. under cadmium stress.

28-Homobrassinolide (28-HBL), a brassinosteroid is reported to play significant role in diverse physiological processes. It induces a range of cellular and adaptive responses to a range of environmental stresses. Cadmium (Cd) is a non-essential metal which alters various physiological processes and generates ROS, which can oxidize biological macromolecules and causes oxidative stress. This stress is generally overcome by the internal antioxidative defense system and stress shielding phytohormones. In this study, effect of 28-HBL was studied on growth and activities of antioxidant enzymes in known hyperaccumulator Raphanus sativus L. (radish) seedlings grown under cadmium (Cd) metal stress. To determine the influence of 28-HBL (0, 10-11, 10-9, 10-7 M) in radish seedlings subjected to Cd (0, 0.5, 1.0, 1.5 mM) stress, the activities of antioxidant enzymes (APOX, CAT, GR, POD and SOD) were analyzed. In addition, length and biomass of radish seedlings was also recorded. Cd toxicity resulted in reduced length, biomass, protein content and activities of antioxidant enzymes. 28-HBL treatments lowered the Cd toxicity by enhancing the activities of antioxidant enzymes, biomass and seedling length. The present study thus suggests a possible role of 28-HBL in amelioration of metal stress by regulating the activities of antioxidant enzymes in radish.