Abstract
BACKGROUND: The heat shock transcription factor (Hsf) is a crucial regulator of plant stress resistance, playing a key role in plant stress response, growth, and development regulation. RESULTS: In this study, we utilized bioinformatics tools to screen 25 VbHsf members, which were named VbHsf1-VbHsf25. We used bioinformatics methods to analyze the sequence structure, physicochemical properties, conserved motifs, phylogenetic evolution, chromosome localization, promoter cis-acting elements, collinearity, and gene expression of Hsf heat shock transcription factor family members under low-temperature stress. The results revealed that the majority of the Hsf genes contained motif1, motif2, and motif3, signifying that these three motifs were highly conserved in the Hsf protein sequence of Verbena bonariensis. Although there were some variations in motif deletion among the members, the domain remained highly conserved. The theoretical isoelectric point ranged from 4.17 to 9.71, with 21 members being unstable proteins and the remainder being stable proteins. Subcellular localization predictions indicated that all members were located in the nucleus. Phylogenetic analysis of the Hsf gene family in V. bonariensis and Arabidopsis thaliana revealed that the Hsf gene family of V. bonariensis could be categorized into three groups, with group A comprising 17 members and group C having at least two members. Among the 25 Hsf members, there were 1-3 exons located on seven chromosome fragments, which were unevenly distributed. Collinearity analysis demonstrated the presence of seven pairs of homologous genes in the VbHsf gene family. The Ka/Ks ratios were less than one, indicating that the VbHsf gene underwent purification selection pressure. Additionally, nine genes in V. bonariensis were found to have collinearity with A. thaliana. Promoter analysis revealed that the promoters of all VbHsf genes contained various types of cis-acting elements related to hormones and stress. Based on RNA-seq data, qRT-PCR analysis of six highly expressed genes was performed, and it was found that VbHsf5, VbHsf14, VbHsf17, VbHsf18, VbHsf20 and VbHsf21 genes were highly expressed at 12 h of low-temperature treatment, and the expression decreased after 24 h, among which VbHsf14 was up-regulated at 12 h of low-temperature by 70-fold. CONCLUSIONS: Our study may help reveal the important roles of Hsf in plant development and show insight for the further molecular breeding of V. bonariensis.