Identification, evolution, and functional characterization of the HSF gene family of <i>Paeonia suffruticosa</i>: implications for high-temperature stress response

The heat shock transcription factor (HSF) family plays a crucial role in regulating plant growth, development, and responses to environmental stresses, particularly those caused by high temperatures and drought. In this study, we systematically characterized the HSF gene family in <italic>Paeonia suffruticosa</italic> and identified 15 PosHSF genes, which exhibited a high degree of conservation in both gene structure and function. Phylogenetic analysis revealed that the PosHSF genes shared strong similarities with the HSF genes of <italic>Arabidopsis thaliana</italic> and could be categorized into three groups (HSF A, HSF B, and HSF C). Furthermore, gene evolution and cis-acting element analyses indicated that the promoter region of PosHSF genes was enriched with multiple regulatory elements involved in plant growth, development, and stress responses—particularly in response to high-temperature stress. WGCNA analysis demonstrated that the expression changes of <italic>PosHSF03</italic> and <italic>PosHSF08</italic> at the early stage of high-temperature treatment suggested their key roles in heat tolerance. This study not only provides new insights into the function of the <italic>P. suffruticosa</italic> HSF gene family but also offers a theoretical foundation for improving stress resistance and driving varietal innovation in <italic>P. suffruticosa</italic>, thereby promoting the high-quality development of the <italic>P. suffruticosa</italic> industry.