Cadmium minimization in rice. A review

Cadmium (Cd) contamination of rice is found in areas irrigated by wastewater from mines. Cd contamination of rice fields can also result from the application of Cd-rich phosphate fertilizers. As a consequence, millions of tons of rice are discarded. In Asia, irrigated paddy-based cropping systems provide rice grains as food for about 2 billion people. A daily intake of 20-40 mu g Cd from rice is reported in regions where rice is used as a food. Daily rice Cd intake leads to diseases such as bone mineralization. Hence, Cd minimization in rice is needed. This article reviews sustainable agriculture and molecular techniques that prevents Cd uptake in rice. Cadmium minimization can be done either by field remediation or change in plant functions. Organic farming decreases Cd uptake and remediates crop fields. Cd hyperaccumulator plants and Cd immobilizing microbes can be used for field remediation. Cd amount in rice can be controlled by gene families that code for putative transition metal transporters or metal chaperones and quantitative trait loci (QTL). Generation of Cd excluder rice is possible by transgenics.