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

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.

Acknowledgements

This study was supported by the earmarked fund for CARS-10-Sweetpotato; the National Key Research and Development Program of China (2021YFC1809100); the Scientific and Technological Innovation Fund of Carbon Emissions Peak and Neutrality of Jiangsu Provincial Department of Science and Technology (BE2022304); the Jiangsu Agriculture Science and Technology Innovation Fund (CX (23) 1019). The yeast cells and expression vectors used in the experiment were kind gifts by professor J. Gong from Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences. The plant expression vectors were provided by professor X. Bian from the Institute of Food Crops, Jiangsu Academy of Agricultural Sciences.

Author contributions

P.D. and X.Z. designed the experiments. P.D., S.Z., Y.F., and M.Z. performed the experiments. Y.Y. and C.C. analyzed the data. P.D. drafted the manuscript. Y.X., L.S., and Y.C. revised and finalized the manuscript. All authors discussed the results and approved the final article.

Data availability

The data supporting the results of this work can be obtained in the paper and its supplementary materials. The genomic data used in this study, derived from the sweetpotato cultivar Taizhong6, can be accessed in the NCBI Genome database under the assembly accession number GCA_002525835.2. https://www.ncbi.nlm.nih.gov/genome/?term=GCA_002525835.2

Conflicts of interest statement

The authors declare that they have no conflict of interest.

Supplementary material

Supplementary material is available at Horticulture Research online.

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