[Genome-wide identification, sequence characteristic and expression analysis of heat shock factors (HSFs) in...

Heat shock factors (HSFs) are ubiquitous in eukaryotes with diversification in structural feature and biological function in plants. Based on the availability of whole cucumber genome sequences, we characterized the cucumber HSFs gene family which contains at least 21 members. Sequence alignments show that all HSFs possess a specific DNA binding domain (DBD). These HSFs genes are unevenly distributed in the seven cucumber chromosomes except for Csa026480 (located on Scaffold_repeat037858). Phylogenetic analysis shows that HSFs in cucumber could be divided into three families, in which family I included three categories (A, B and C). Phylogenetic tree also reveals nine pairs of orthologous genes and three pairs of paralogous genes, suggesting that HSFs gene family have existed before the separation of cucumber and Arabidopsis thaliana. EST analysis shows that cucumber HSFs may be involved in the development of fruit, female flower and hermaphrodite flower. qRT-PCR analysis demonstrated that these genes exhibit different expression levels in heat stress treatment. These results will provide a foundation for the functions of the HSF gene family.