Genome wide investigation of Hsf gene family in Phoebe bournei: identification, evolution, and expression after abiotic stresses

Heat shock transcription factors(Hsfs) have important roles during plant growth and development and responses to abiotic stresses. The identification and function of Hsf genes have been thoroughly studied in various herbaceous plant species, but not woody species, especially Phoebe bournei, an endangered, unique species in China. In this study, 17 members of the Hsf gene family were identified from P. bournei using bioinformatic methods. Phylogenetic analysis indicated that Pb Hsf genes were grouped into three subfamilies: A, B, and C. Conserved motifs, threedimensional structure, and physicochemical properties of the Pb Hsf proteins were also analyzed. The structure of the Pb Hsf genes varied in the number of exons and introns. Prediction of cis-acting elements in the promoter region indicated that Pb Hsf genes are likely involved in responses to plant hormones and stresses. A collinearity analysis demonstrated that expansions of the Pb Hsf gene family mainly take place via segmental duplication. The expression levels of Pb Hsf genes varied across different plant tissues. On the basis of the expression profiles of five representative Pb Hsf genes during heat, cold, salt, and drought stress, Pb Hsf proteins seem to have multiple functions depending on the type of abiotic stress. This systematic, genome-wide investigation of Pb Hsf genes in P. bournei and their expression patterns provides valuable insights and information for further functional dissection of Hsf proteins in this endangered, unique species.