Abstract：Wheat (Triticum aestivum) is one of the most important food crops in China. High temperature and other abiotic stresses seriously affect the yield and quality of wheat. The discovery and identification of resistance genes can provide candidate genes and theoretical foundation for wheat stress resistance breeding. Heat shock proteins (Hsps) are crucial molecular chaperones that preserving cellular function under stress conditions and regarded as significant candidate genes for heat resistance. In this study, the TaHsp17.9 gene (GenBank No. MN684335) of wheat was amplified by PCR using the cDNA of the heat tolerance wheat variety 'Pingyao Xiaobaimai' as a template. The total CDS length of TaHsp17.9 is 474 bp, encoding 157 amino acids. The protein sequence of TaHsp17.9 contains the specific α-crystallin domain (ACD) of plant small heat shock protein (sHsp). Phylogenetic tree analysis indicated that Hsp17.9 had the closest genetic distance to Triticum dicoccoides. qPCR results showed that the expression levels of TaHsp17.9 were highest in grain and lowest in root. The TaHsp17.9 was induced to express by high temperature and drought stress, and its expression level reached the peak at 1 and 2 h respectively. The expression level of TaHsp17.9 in heat tolerance varieties was significantly higher than that in heat sensitive varieties under the heat stress. The results of subcellular localization showed that TaHsp17.9 protein was localized in the cytoplasm. Identification of heat tolerance in the TaHsp17.9 overexpression strain of Arabidopsis thaliana, the result showed that, overexpression of TaHsp17.9 could significantly improve the heat tolerance of transgenic Arabidopsis thaliana. In addition, 10 candidate interacting proteins that might interact with TaHsp17.9 were obtained based on STRING database. This study provides a reference for further studying the function of TaHsp17.9 gene in wheat.
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