A CRITICAL REVIEW ON THE EFFECT AND TOXICITY OF CADMIUM MEDIATED STRESS IN PLANTS

Cadmium (Cd) is one of the non-essential and highly toxic environmental pollutants. It causes serious environmental and agricultural problems. It ranks seventh on the list of the twenty most toxic metals. Dietary cadmium intake is much higher than the upper limit reported by FAO/WHO. Sources of environmental Cd contamination, soil factors affecting Cd uptake, Cd dynamics in the soil rhizosphere, uptake mechanisms, Cd transport and toxicity in plants. In crops, Cd toxicity reduces nutrient and water uptake and transport, increases oxidative damage, disrupts plant metabolism, and disrupts plant morphology and physiology. Factors effecting the uptake and translocation of Cd in plants are elaborated to understand the mechanism that contributes to its accumulation. Cadmium disturbs the function of chloroplasts by accumulating to higher levels in aerial parts. It inhibits the enzymes needed for chlorophyll biosynthesis as well as enzymes for carbon dioxide fixation Ribulose-1, 5-biphosphate carboxylase (RUBPCase) and phosphoenol pyruvate carboxylase (PEPCase). Using molecular techniques, including identification of QTLs, CRISPR/Cas9, and functional genomics, to amplify the adverse effects of Cd on plants is of great utility. This review also discussed on the phytoremediation techniques like phyto extraction, phyto stimulation, phyto stabilization, phytovolatization and rhizofiltration to combat against cadmium toxicity.