Assessment of Divalent Metal-Toxicity and the Role of 24- Epibrassinolide in Triticum Aestivum Seedlings

Reports on the metal-toxicity are extensive; however, literature is scarce on the role of sustainable stress-mitigation approaches in this context. This work investigated the significance of growth regulator 24-epibrassinolide (24-EpiBL; 1.0 µM) in the mitigation of consequences of low (10 µM) or high (1.0 mM) concentrations of plant-beneficial (Cu2+, Zn2+, and Ni2+) and plant-non-essential (Pb2+ and Sr2+) divalent metals in wheat (Triticum aestivum L.) seedlings. Apart from studying the changes in root and shoot growth, the status of oxidative stress and its metabolism (in terms of superoxide anion, •O2 − ; lipid peroxidation, LPO; catalase, CAT) was assessed as major markers of Cu2+, Zn2+, Ni2+, Pb2+ and Sr2+ -accrued consequences. At high concentrations, plant-beneficial divalent metals (particularly Cu2+ and Ni2+) and plant-non-essential divalent metals (Pb2+ and Sr2+) significantly enhanced •O2 − -generation, LPO and CAT activity in T. asetivum leaves and also inhibited the axial growth. Pretreatment of seeds with 24-EpiBL protected T. aestivum seedlings by differentially minimizing the impacts of particularly Zn2+, Ni2+, and Pb2+ (up to 10 µM), and diminished oxidative stress and improved overall growth. 24-EpiBLmediated elevation in CAT activity and subsequent control of cellular •O2 − and its consequence (LPO) can be convincing mechanism that eventually resulted into 24-EpiBL-mediated improved root and shoot growth traits in T. aestivum when exposed to low (10 µM) concentration of essential divalent metals (Zn2+, Cu2+ and Ni2+) as well as phytotoxic divalent metal (Pb2+).