Metallochaperone protein OsHIPP53 reduces cadmium accumulation in rice (Oryza sativa L.) roots

Cadmium (Cd) pollution represents a widespread environmental issue in agricultural regions in China, adversely affecting crop productivity and threatening food safety. Heavy metal-associated isoprenylated plant proteins (HIPPs), a major class of metallochaperone proteins, are essential for plant adaptation to diverse biotic and abiotic stress conditions. This study characterizes a previously uninvestigated HIPP gene, OsHIPP53, demonstrating its involvement in modulating Cd accumulation and tolerance in rice. Subcellular localization analysis revealed that OsHIPP53 is primarily localized at the plasma membrane and Cd exposure significantly induced its transcriptional level in root tissues. Heterologous expression of OsHIPP53 in Δycf1 yeast mutants conferred improved Cd resistance and reduced cellular Cd levels relative to yeast cells carrying the empty vector. Consistent with yeast findings, in rice, oshipp53 mutant lines (oshipp53-1 and oshipp53-2) exhibited heightened Cd sensitivity, elevated root Cd concentrations, and restricted Cd translocation to the shoots. Conversely, overexpression lines (OsHIPP53-OX-1 and OsHIPP53-OX-2) displayed greater Cd tolerance and Cd accumulation in the shoots. Taken together, these results suggested that OsHIPP53 functions in regulating Cd accumulation and tolerance in rice by facilitating the cellular efflux process of Cd.