Cloning and characterization of drought tolerance function of kinase gene IbHT1 in sweetpotato

HT1 (HIGH LEAF TEMPERATURE 1) is a protein kinase known for its role in regulating stomatal movement in Arabidopsis. However, its function in sweetpotato has not been reported. In this study, the IbHT1 gene was cloned from the sweetpotato line Xushu 55-2. The full-length CDS of IbHT1 is 1140 bp, encoding a 379-amino acid protein that contains a conserved STKc_MAP3K_Like domain, with a predicted molecular weight of 43.07 kD and an isoelectric point (pI) of 8.83. The genomic sequence of IbHT1 spans 2796 bp, comprising 3 exons and 2 introns. Subcellular localization analysis revealed that the IbHT1 protein is localized to the cell membrane, and yeast assays confirmed it lacks transactivation activity. Expression of IbHT1 was down-regulated in response to 20% PEG-6000 treatment. Overexpression of IbHT1 significantly reduced drought tolerance in sweetpotato, while RNA interference (RNAi) of IbHT1 markedly enhanced drought tolerance. Additionally, 10 proteins interacting with IbHT1 were identified through yeast library screening. These findings suggest that IbHT1 may regulate drought tolerance in sweetpotato by interacting with other proteins.