Comparative identification, characterization, and expression analysis of bZIP gene family members in watermelon and melon genomes

Abstract

The family of basic leucine zipper (bZIP) transcription factors plays diverse crucial roles in numerous biological processes. Despite the identification of bZIP genes in several plants, to our knowledge, bZIP members in watermelon and melon are yet to be comprehensively investigated. The genomes of watermelon and melon encode 59 ClabZIP and 75 CmbZIP putative genes, respectively. Both bZIP protein family members were phylogenetically grouped into seven subfamilies. The majority of bZIP genes in the same subfamily shared similar gene structures and conserved motifs. Chromosome distribution and genetic analysis revealed that 21 duplication events between ClabZIP genes and 106 duplication events between CmbZIP genes have occurred. Further, the three-dimensional structure and functional annotation of bZIP proteins was predicted. For evaluating the expression patterns of ClabZIP and CmbZIP genes, RNA-seq data available in public databases were analyzed. The expression profiles of selected ClabZIP and CmbZIP genes in root and leaf tissues of drought-stressed watermelon and melon were also examined using qRT-PCR. ClabZIP-57, CmbZIP-52, and CmbZIP-31 genes exhibited the highest expression levels after stress exposure in leaf and root tissues. Gene identification studies like the present study offer new perspectives in the analysis of bZIP protein family members and their functions in plants.