Co-mutation of OsLPR1/3/4/5 provides a promising strategy to minimize Cd contamination in rice grains.

ABSTRACT

Minimizing cadmium (Cd) contamination in rice grains is crucial for ensuring food security and promoting sustainable agriculture. Utilizing genetic modification to generate rice varieties with low Cd accumulation is a promising strategy due to its cost-effectiveness and operational simplicity. Our study demonstrated that the CRISPR-Cas9-mediated quadruple mutation of the multicopper oxidase genes OsLPR1/3/4/5 in the japonica rice cultivar Tongjing 981 had little effect on yields. However, a notable increase was observed in the cell wall functional groups that bind with Cd. As a result, the quadruple mutation of OsLPR1/3/4/5 enhanced Cd sequestration within the cell wall while reducing Cd concentrations in both xylem and phloem sap, thereby inhibiting Cd transport from roots to shoots. Consequently, Cd concentrations in brown rice and husk in oslpr1/3/4/5 quadruple mutants (qm) decreased by 52% and 55%, respectively, compared to the wild-type. These findings illustrate that the quadruple mutation of OsLPR1/3/4/5 is an effective method for minimizing Cd contamination in rice grains without compromising yields. Therefore, the quadruple mutation of OsLPR1/3/4/5 via biotechnological pathways may represent a valuable strategy for the generation of new rice varieties with low Cd accumulation.