Genome-Wide Identification and Heat Stress-Induced Expression Profiling of the Hsp70 Gene Family in Phoebe bournei

<i>Phoebe bournei</i>, a rare tree species native to China, holds considerable economic importance. The heat shock protein 70 (Hsp70) family is a group of molecular chaperones that is broadly distributed across living organisms and play a critical role in processes like growth, development, and stress response. While <i>Hsp70</i> genes have been identified and studied in various plant species, their specific functions in the growth and development of <i>P. bournei</i> remain unexplored. We performed a comprehensive analysis of the <i>Hsp70</i> gene family in <i>P. bournei</i>, identifying a total of 45 <i>Hsp70</i> genes, which were classified into four groups (I-IV) through phylogenetic analysis. All Hsp70 proteins possessed conserved structural domains, including motif 7, and introns were present in 77.8% of the genes. Chromosomal localization and collinearity analyses of the <i>Hsp70</i> genes revealed their evolutionary relationships and potential gene duplication events. Examination of the cis-acting elements within the Hsp70 promoter regions revealed that the predominant elements were associated with growth and development, followed by those responsive to hormones, and then elements linked to abiotic stress. Nine genes with high expression were selected for RT-qPCR analysis. Under high-temperature stress, all nine genes were differentially upregulated, and most of these genes belonged to subfamilies II and III, indicating that these two subfamilies have strong potential for heat resistance. In this study, we have elucidated the molecular characteristics and heat response properties of the <i>Hsp70</i> gene family in <i>P. bournei</i>, revealing the mechanisms behind its heat stress response. Our work provides a reference for stress breeding in <i>P. bournei</i> and a theoretical basis for the exploration of heat tolerance in woody plants.