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

TL;DR

A new gene in sweetpotato helps reduce cadmium toxicity by limiting its accumulation in plants, offering a way to grow safer crops.

Contribution

The study identifies and functionally characterizes a novel HIPP gene, IbHIPP7, involved in cadmium tolerance and transport in sweetpotato.

Findings

IbHIPP7 is localized to the plasma membrane and contains two conserved HMA domains crucial for cadmium tolerance.

Overexpression of IbHIPP7 in sweetpotato significantly reduces cadmium accumulation in roots and shoots.

The gene enhances cadmium tolerance by decreasing cadmium absorption in plants.

Abstract

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, IbHIPP7, and investigated its role in Cd transport and tolerance. Subcellular localization revealed that IbHIPP7 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 IbHIPP7 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.

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