Strategies for reducing cadmium accumulation in rice grains

A high concentration of toxic heavy metal cadmium (Cd) in the paddy soils and its translocation and subsequent accumulation in the rice grain and the food chain is a global environmental issue. Mechanistic understanding of soil properties that affects the uptake and translocation of Cd in rice may help to reduce Cd uptake by rice plants and its accumulation in the grains. This review discusses the known and unknown soil and plant factors involved in the transportation of Cd from the soil through roots into rice grains. Various management practices to remediate Cd from contaminated soil are known, but only a few of these technologies are practically applicable in the field. The use of effective, ecofriendly, and natural resource-based remediation practices and understanding of their underlying mechanism is indispensable. The translocation of Cd from soil to rice roots may be reduced by controlling soil pH and redox potential through wise management of nutrients and water. The uptake and translocation of Cd and its accumulation in rice grains may be reduced by developing genotypes restricting Cd uptake. This can be achieved through breeding and identifying Cd tolerant genes followed by knocking out and/or editing these genes via CRISPR/Cas9 technique.