The SnRK2 family in pepper (Capsicum annuum L.): genome-wide identification and expression analyses during fruit...

Plant-specific SnRK2 (sucrose nonfermenting-1-related protein kinase 2) genes play crucial roles in the coordination of plant growth and development and responses to stress. However, comprehensive studies have not been performed for this gene family in pepper (Capsicum annuum), a very important Solanaceous vegetable worldwide. To fully understand the status of SnRK2s in chili pepper, a total of 9 putative SnRK2 genes (named CaSnRK2.1-2.9) were identified in pepper in the present study. These genes were located on 7 different chromosomes and classified into three subfamilies based on the phylogenetic tree. Their conserved motif compositions and exon-intron structures were systematically analyzed, and the results strongly supported the classification. Furthermore, a total of 81 putative cis-elements were found in the promoter regions, and the cis-elements related to hormone and stress signaling were abundant. Finally, the CaSnRK2 gene expression profiles among different tissues, especially developing fruit tissue, and under various abiotic stresses were investigated to identify tissue-specific or stress-responsive candidates. This study was the first to comprehensively investigate the SnRK2 family in pepper, and the results provide important clues for further functional analyses of fruit development and abiotic stress responses.