Calcium induces phytochelatin accumulation to cope with chromium toxicity in rice (Oryza sativa L.)

Heavy metal chromium (Cr) is considered to be a serious environmental contaminant due to its toxic effect on living organisms. To mitigate and reduce the negative impacts of Cr in rice plant, the effect of exogenous supplementary calcium was evaluated as it functions as a signaling molecule at cellular level. In this study, growth parameters, protein content, and membrane stability were found to be restored due to calcium under Cr stress. Further, Atomic absorption spectrophotometric analysis revealed that calcium inhibits Cr translocation from root to shoot in rice seedlings. This event was addressed by the enhanced accumulation of phytochelatin that leads to vacuolar sequestration of Cr in roots. Furthermore, increased activity of Catalase, Peroxidase, and Glutathione reductase along with elevated glutathione also assures that calcium enhances antioxidant defense mechanism to cope with Cr toxicity. Abbreviations: Chromium: Cr; Iron: Fe; Calcium: Ca2+; PC: Phytochelatin; ROS: Reactive oxygen species; CAT: Catalase; POD: Peroxidase; SOD: Superoxide dismutase; GR: Glutathion reductase