Whole-genome identification and expression characterization of the HSFP gene family of Triticum aestivum under heat and drought stress

Background

HSF-type DNA-binding domain-containing proteins (HSFPs) are key transcription factors that regulate plant responses to abiotic stresses, including heat and drought. As a staple crop, Triticum aestivum faces increasing threats from climate change, making it critical to understand the molecular mechanisms of HSFP-mediated stress adaptation. While HSF families have been studied in model plants, systematic analysis of Triticum aestivum HSFP genes, particularly their evolutionary divergence and stress-responsive regulation, remains limited.

Results

Using bioinformatics approaches, we identified 81 non-redundant TaHSFP genes in the Triticum aestivum genome (Triticum aestivum refseqv2.1). These genes are unevenly distributed across all 21 chromosomes, encoding proteins with 227–569 amino acids, isoelectric points (pI) ranging from 4.81 to 9.52, and instability indices of 32.26–71.13. Phylogenetic analysis classified TaHSFP proteins into five distinct evolutionary lineages, showing expanded complexity compared to Arabidopsis and rice. Structural characterization revealed 10 conserved motifs (Motif 1–10) and prevalent bi-exonic (62 genes) or tri-exonic (10 genes) architectures. Promoter regions of TaHSFP genes are enriched with stress-responsive cis-elements (e.g., abscisic acid, drought, and heat shock elements), and subcellular localization predictions indicate 75 proteins target the nucleus, 4 the cytoplasm, and 2 chloroplasts. Expression profiling using transcriptome data and qRT-PCR (3 biological replicates, 2 technical replicates) showed tissue-specific expression, with 37 TaHSFP genes highly expressed in leaves and stems. Under heat (40°C), drought (20 % PEG-6000), and combined stress, 12 TaHSFP genes (e.g., TraesCS7B03G0454600.1, TraesCS5A03G0601000.1) were significantly upregulated (log2FC > 2, p < 0.05), with the highest induction (269-fold) observed for TraesCS7B03G0454600.1 under 1 h heat stress. Protein-protein interaction (PPI) network analysis predicted 60 core TaHSFP proteins with 1047 interactions, enriched in heat shock response pathways (GO:0009408).

Conclusions

This study provides the first comprehensive analysis of the Triticum aestivum HSFP gene family, revealing their evolutionary and functional diversity. The identified stress-responsive TaHSFP genes and their regulatory motifs offer novel targets for improving Triticum aestivum resilience to climate stress via molecular breeding.