Overexpression of Silicon Uptake Transporter OsLsi1 and OsLsi2 Decreased Cadmium Accumulation in Rice

Silicon (Si) fertilizer reduces cadmium (Cd) accumulation in rice; whether the rice Si uptake genes mediate this process remains unclear. This study investigated how overexpressing OsLsi1 and OsLsi2 affects Cd accumulation in rice. Compared to wild-type ZH11, OsLsi1 and OsLsi2 expression increased by 5- and 150-fold in roots, respectively. The overexpression of OsLsi1 reduced root Cd, while that of OsLsi2 decreased shoot Cd in the seedlings. Both lines showed lower Cd in xylem sap, dependent on Si, and alleviated Cd-induced root stress. At maturity, grain Cd decreased by 44-66% and straw Cd by 45-65%, without altering the levels of other metals except iron. Cd uptake (OsIRT1, OsIRT2, OsNRAMP1, and OsNRAMP5) and translocation (CAL1, OsHMA2) genes were downregulated in roots. Crucially, agronomic traits remained unaffected. These findings demonstrate that OsLsi1/OsLsi2 overexpression reduces Cd accumulation by suppressing Cd-related genes, offering a promising approach to safer rice production.