Disruption of OsGONST3 reduces grain cadmium accumulation without yield penalty in field-grown rice

Cadmium (Cd) pollution in paddy soils threatens global food safety. Identifying molecular gateways controlling grain Cd accumulation is essential for breeding low-Cd rice. A field-based screen of a large-scale CRISPR/Cas9 mutant library identified OsGONST3, a Golgi nucleotide sugar transporter family member localized to the plasma membrane. After 1 μM Cd treatment for 7 d, OsGONST3 transcript abundance increased approximately 3.4-fold in root and 5.7-fold in shoot, accompanied by increased OsGONST3-GFP protein accumulation. Heterologous OsGONST3 expression increased yeast Cd content by approximately 23% relative to the empty-vector control. Under hydroponic exposure to 1 μM Cd for 7 d, two independent osgonst3 mutants contained 22-25% less Cd in root, approximately 13% less in shoot, and 16-21% less in xylem sap than Nipponbare. Conversely, OsGONST3-overexpressing lines contained 40-42%, 38-40%, and 28-37% more Cd in root, shoot, and xylem sap, respectively. Under tested field condition, OsGONST3 disruption reduced grain Cd by approximately 25-26% without a significant yield penalty and was associated with secondary transcriptional adjustments in Cd-homeostasis genes. These findings identify OsGONST3 as a plasma membrane-localized Cd influx-associated protein and a promising target for breeding low-Cd rice.