Overexpression of the heavy metal-associated isoprenylated plant protein gene <i>IbHIPP7</i> reduces cadmium accumulation and alleviates cadmium toxicity in sweetpotato

Cadmium (Cd) contamination in farmland soils poses a potential threat to crop safety and human health. Heavy metal-associated isoprenylated plant proteins (HIPPs), a unique group of proteins in vascular plants, play a crucial role in abiotic and biotic stress responses. However, their functional characterization remains limited. In this study, we identified a novel sweetpotato HIPP gene, <i>IbHIPP7</i>, and investigated its role in Cd transport and tolerance. Subcellular localization revealed that <i>IbHIPP7</i> is localized to the plasma membrane. Functional domain analysis indicated that two conserved heavy metal-associated (HMA) domains, but not the C-terminal isoprenylation motif, are essential for Cd tolerance. Transgenic sweetpotato (cultivar Sushu33) overexpressing <i>IbHIPP7</i> exhibited significantly enhanced Cd tolerance and reduced Cd accumulation in roots and shoots compared to wild-type (WT) plants. These results indicate that IbHIPP7 reduces Cd toxicity by decreasing Cd absorption and thereby enhancing Cd tolerance, providing a molecular basis for developing low-Cd-accumulating sweetpotato varieties to enhance agricultural safety.