Genome-Wide Characterization of the Heat Shock Transcription Factor Gene Family in Betula platyphylla Reveals Promising Candidates for Heat Tolerance

Heat stress transcription factors (HSFs) play a critical role in orchestrating cellular responses to elevated temperatures and various stress conditions. While extensively studied in model plants, the <i>HSF</i> gene family in <i>Betula platyphylla</i> remains unexplored, despite the availability of its sequenced genome. In this study, we employed bioinformatics approaches to identify 21 <i>BpHSF</i> genes within the <i>Betula platyphylla</i> genome, revealing their uneven distribution across chromosomes. These genes were categorized into three subfamilies: A, B, and C. Each was characterized by conserved protein motifs and gene structures, with notable divergence observed between subfamilies. Collinearity analysis suggested that segmental duplication events have driven the evolutionary expansion of the <i>BpHSF</i> gene family. Promoter region analysis identified an array of cis-acting elements linked to growth, development, hormonal regulation, and stress responses. Subcellular localization experiments confirmed the nuclear localization of <i>BpHSFA2a</i>, <i>BpHSFB1a</i>, and <i>BpHSFC1a</i>, consistent with in silico predictions. RNA-seq and RT-qPCR analyses revealed tissue-specific expression patterns of <i>BpHSF</i> genes and their dynamic responses to heat stress, with qPCR validation highlighting a significant upregulation of <i>BpHSFA2a</i> under high-temperature conditions. In summary, this study provided a comprehensive characterization of the <i>HSF</i> gene family in <i>Betula platyphylla</i>, laying a solid foundation for future functional studies. Particularly, <i>BpHSFA2a</i> emerges as a promising candidate gene for enhancing heat tolerance in <i>Betula platyphylla</i>, warranting further detailed investigation.