Sweetpotato is one of the world’s most important food crops, and in many vegetable-type cultivars, young shoots and leaves are consumed as nutrient-rich greens. Yet cadmium pollution in agricultural soils threatens exactly these edible tissues, because cadmium can enter roots, move upward through the plant, and accumulate in aboveground organs. Although many metal transporters involved in cadmium movement have been reported in plants, the relevant mechanisms in sweetpotato have remained poorly understood. Members of the HIPP family are known to participate in heavy-metal detoxification, but their functions in sweetpotato were still largely unclear. Based on these challenges, deeper research into the molecular basis of cadmium absorption, transport, and detoxification in sweetpotato is urgently needed.
A team from Nanjing Agricultural University, working with collaborators from the University of Tokyo, reported (DOI: 10.1093/hr/uhaf323) on December 8, 2025 in Horticulture Research that the sweetpotato gene IbHIPP7 reduces cadmium accumulation and alleviates cadmium toxicity by lowering cadmium uptake and improving plant tolerance under stress.
The study followed IbHIPP7 from discovery to functional validation across several biological systems. Researchers first identified the gene as cadmium inducible and found that it is mainly expressed in leaves, while cadmium treatment strongly stimulated its expression in petioles. Subcellular experiments then showed that the IbHIPP7 protein is localized to the plasma membrane, placing it at a strategic site for controlling metal movement into cells. In yeast, expression of IbHIPP7 enhanced cadmium tolerance and lowered intracellular cadmium content by about 40%, revealing a direct detoxification role. Domain analysis added an important mechanistic clue: the gene’s two HMA domains were essential for cadmium tolerance, whereas the C-terminal isoprenylation motif was not. The gene also showed notable specificity, helping detoxify cadmium rather than other divalent metals such as copper, manganese, zinc, or iron. In Arabidopsis and transgenic sweetpotato, overexpression of IbHIPP7 reduced cadmium accumulation, weakened root cadmium influx, preserved leaf greenness, limited ROS damage, and improved plant growth in cadmium-contaminated soil. In whole sweetpotato plants, cadmium concentrations fell by 28% in roots, 42% in stems, and 38% in leaves.
“This study turns IbHIPP7 from a candidate gene into a convincing functional target for crop safety,” the researchers suggest in essence. Rather than merely showing an association with stress, the work demonstrates how one sweetpotato gene can influence cadmium uptake, tissue accumulation, and physiological injury across yeast, Arabidopsis, hairy roots, and whole plants. That cross-system consistency makes the finding especially persuasive and gives the gene real translational value for agriculture.
The implications extend beyond one crop. Sweetpotato is both a staple food and a leafy vegetable, so reducing cadmium in its edible tissues could directly improve dietary safety in contaminated production areas. The identification of IbHIPP7 provides breeders with a promising genetic resource for developing low-cadmium cultivars and offers new insight into how plants regulate toxic metal entry at the cellular boundary. More broadly, the work strengthens efforts to combine molecular breeding with environmental adaptation, helping agriculture remain productive even under soil pollution pressure. In a time when food security must also mean food safety, IbHIPP7 offers a practical and biologically grounded starting point.
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References
DOI
10.1093/hr/uhaf323
Original Source URL
https://doi.org/10.1093/hr/uhaf323
Funding information
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).
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.