Identification and expression analysis of HSF transcription factor family in wild jujube under heat stress

Heat shock transcription factor (HSF) is one of the important transcription factor families in plants, which plays an important role in the response to biological and abiotic stresses. In this study, based on the transcriptional data of wild jujube (Ziziphus acidojujuba C.Y. Cheng et M.J. Liu) under heat stress, bioinformatics was used to identify and analyze the HSF transcription factor family of wild jujube, and they were named ZjHsf1-ZjHsf20 according to the sequence of chromosomal location, among which, ZjHsf1-ZjHsf17 were unevenly distributed on the 12 chromosomes of jujube; the number of amino acids of all ZjHsf genes ranged from 217 to 560, and most of them were acidic proteins with relatively stable protein structure. Sequence alignment and phylogenetic tree results showed that there was a highly conserved DBD domain in the ZjHsf protein, and the ZjHsf gene family members were divided into A, B and C type according to the number of residual between A and B in the HR-A/B domain. According to the classification of the Arabidopsis Hsf gene family, class A was subdivided into nine subclasses A1-A9, and class B was subdivided into four subclasses B1-B4. The results of conserved motifs and gene structure showed that all ZjHsf genes contained DBD structure, which was composed of Motif1 and Motif2; all ZjHsf genes contain exon and intron structures, and the number of introns varies from 1 to 3. Analysis of cis-elements in the promoter region showed that the promoter sequence of ZjHsf gene contained STRE, MBS, ABRE and other cis-acting regulatory elements that respond to stress. The heat map analysis showed that all ZjHsf genes were involved in the defense response to high temperature stress in wild jujube.