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.

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Ethylene diamine tetraacetic acid (EDTA) is a chelating agent used worldwide for the phytoextraction of heavy metals as well as household and industrial purposes and persists in the cultivated land for a long time. In this study, the effect of EDTA in the presence and in absence of heavy metal (Chromium) was evaluated on non-hyper accumulating plant rice (Oryza sativa L.) on the hydroponic solution at the cellular and molecular level. EDTA application enhanced phytochelatin (PC) and metallothionein (MT) synthesis, which was assured by up regulation of phytochelatin and metallothionein gene in rice root. However, lower quantity of EDTA (25µM) along with chromium enhanced the chromium (Cr) uptake in root but inhibited its translocation to shoot pointing vacuolar sequestration of excessive chromium in root. One the other hand, in absence of chromium, H2O2 concentration is found to be increased which significantly enhanced electrolyte leakage and lipid peroxidation compared with control plants. The findings of this investigation exhibited that excessive PCs and MTs owing to EDTA enhance reactive oxygen species (ROS) generation in absence of heavy metal (Chromium).