Genome-Wide Identification and Expression Analysis of the HSF Gene Family in Poplar

The Heat Shock Factor (HSF) transcription factor family plays crucial roles in plant growth and development, as well as in protecting against adverse stresses. However, studies on the functions and regulatory mechanisms of the HSF genes are limited in poplar. Here, we identified and classified 30 HSF transcription factors in Populus trichocarpa based on recent genomic data and annotation information and conducted a comprehensive analysis of these proteins, including phylogenetic and physicochemical properties analysis, domain characterization, subcellular localization prediction, cis-acting elements analysis, sequence structure analysis, and chromosomal distribution. Our analysis revealed that segmental duplication events may be the main driving force behind the expansion of the poplar HSF gene family, and we explored the collinearity between poplar HSF genes and those of six other representative species. We also analyzed the tissue-specific and hormonal responses of the HSF genes in poplar and conducted gene co-expression network analysis, which revealed important molecular functions and biological processes related to growth and development, biotic and abiotic stress response, and epigenetic modification. These results provide significant insights into the functions and regulatory mechanisms of the HSF genes in poplar.