OsSultr1;1 and OsZIP4 mediate cadmium uptake and transport in rice: evidence from high and low Cd-accumulators.

Cadmium (Cd) accumulation in rice poses a serious threat to food safety and human health. However, the molecular mechanisms underlying Cd uptake, enrichment and translocation across different rice varieties remain unclear. Here, we identified R66 and R41 as high- and low-Cd-accumulating cultivars, respectively, through screening of 110 rice cultivars. Phenotypic and physiological comparisons were conducted, and root transcriptomics analyzed to identify key genes responsible for Cd uptake and translocation. We identified two candidate genes, OsSultr1;1 and OsZIP4, as possible regulators of Cd accumulation in rice. In short-term hydroponic validation assays at the seedling stage under 5 μM Cd stress, knockout of OsSultr1;1 decreased Cd concentrations in roots by approximately 40%, suggesting its involvement in modulating Cd uptake. Knockout of OsZIP4 reduced shoot Cd concentrations by 45% and significantly lowered the translocation factor, suggesting that OsZIP4 is involved in the long-distance transport of Cd. Overall, this study further elucidates the candidate gene-mediated pathways influencing Cd uptake and translocation in different rice varieties at the early developmental stage, providing a crucial theoretical foundation for breeding low-Cd-accumulating rice to enhance food safety.