Molecular Mechanisms and Mitigation Strategies of Cadmium Accumulation in Rice for Food Safety

Cadmium (Cd) contamination of rice (Oryza sativa L.) grains remains a major food safety concern. Although mechanisms of Cd uptake, sequestration, transport, and grain allocation have been widely studied, important gaps remain. Overexpression of OsHMA3 can reduce grain Cd accumulation by 94-98%, whereas OsNRAMP5 disruption markedly decreases Cd uptake and grain accumulation under contaminated field conditions. Nevertheless, mitigation strategies developed under controlled conditions often perform inconsistently in the field. This review proposes an integrated soilto-grain framework that links rhizosphere processes with Cd transport and redistribution in plants. We emphasize that Cd transport is closely associated with the homeostasis of essential micronutrients, particularly Mn, Zn, and Fe. Consequently, single-target interventions may inadvertently disturb the micronutrient balance and compromise yield. Future breeding of low-Cd rice varieties should adopt coordinated multinode optimization by integrating allele mining, precision breeding, agronomic management, and AI-assisted multiobjective modeling to improve field stability and grain quality.