TaHsfA2-1, a new gene for thermotolerance in wheat seedlings: Characterization and functional roles

Heat shock transcription factors (Hsfs) play an important role in regulating heat stress response in plants. Our previous study found that there were 82 non-redundant Hsfs in wheat, 18 of which belonged to subclass A2. In this study, we cloned an A2 member, TaHsfA2-1, which encoded a protein of 346 amino acid residues in wheat. The fusion protein TaHsfA2-1-GFP was localized in the nucleus under normal growth conditions. TaHsfA2-1 was expressed in nearly all the measured tissues, most highly in mature leaves. The expression level of TaHsfA2-1 can be enhanced by heat stress, PEG stress, and signal molecules such as H₂O₂ and SA. Yeast cells transformed with TaHsfA2-1 improved thermotolerance compared to those with the empty vector. TaHsfA2-1-overexpressing Arabidopsis displayed a better growth state with more green leaves than wild-type seedlings after heat stress. Accordingly, the chlorophyll content and survival rate in the transgenic lines were higher than in the wild type, and relative conductivity in the transgenic lines was lower than in the wild type. Further research found that TaHsfA2-1-overexpressing Arabidopsis up-regulated the expression of some heat shock protein genes (Hsps) compared to wild type after heat stress. These results suggested that TaHsfA2-1 is a new gene that improves thermotolerance in plants by mediating the expression of Hsps. A functional gene was provided for molecular breeding in the subsequent research.