Functional Identification Reveals That TaTGA16-2D Promotes Drought and Heat Tolerance

The TGACG motif-binding factor (TGA) family is an important group of basic region/leucine zipper (bZIP) transcription factors in plants, playing crucial roles in plant development and stress responses. This study conducted a comprehensive genome-wide analysis of the TGA transcription factor (TF) family in common wheat (Triticum aestivum L.). A total of 48 wheat TGAs were identified and classified into four subgroups. Collinearity analysis of the TGAs between wheat and other species identified multiple duplicated gene pairs and highlighted the presence of highly conserved TGAs in wheat. Whole-genome and segmental duplications were identified as the primary drivers of TaTGA expansion. Expression pattern analysis indicated that TaTGAs are involved in plant development and responses to abiotic stresses, including drought, heat, and cold treatment. Among these, TaTGA16-2D was significantly upregulated under both drought and heat stresses, showing more than a five-fold increase in expression. Subcellular localization confirmed its nucleus localization. Functional validation through ectopic expression in Arabidopsis demonstrated that transgenic lines overexpressing TaTGA16-2D exhibited significantly improved stress tolerance. Under heat stress, the survival rates of transgenic lines exceeded 34%, compared to less than 18% in wild-type plants. Overall, this study provides valuable insights into the evolution and functional roles of TaTGAs and identifies TaTGA16-2D as a promising candidate to enhance abiotic stress tolerance in wheat via molecular breeding.