Identification and expression profile analysis of the SnRK2 gene family in cucumber.

The sucrose non-fermenting-1-related protein kinase 2 (SnRK2) is a plant-specific type of serine/threonine protein kinase that plays an important role in the physiological regulation of stress. The objective of this study was to identify and analyze the members of the SnRK2 gene family in cucumber and lay a foundation for further exploration of the mechanism of resistance to stress. Here, 12 genes were isolated from cucumber and distributed on five chromosomes, phylogenetic clustering divided these into three well-supported clades. In addition, collinearity analysis showed that the gene family underwent purifying selection pressure during evolution. genes of the same group have similar exons and conserved motifs, and intron length may be a specific imprint for the evolutionary amplification of the gene family. By predicting cis elements in the promoter, we found that the promoter region of gene members had various cis-regulatory elements in response to hormones and stress. Relative expression analysis showed that (group II) and (group III) were strongly induced by ABA, NaCl and PEG stress; whereas (group III) was not activated by any treatment. The response of group I to ABA, NaCl and PEG was weak. Furthermore, protein interaction prediction showed that multiple CsSnRK2 proteins interacted with four proteins including protein phosphatase 2C (PP2C), and it is speculated that the genes may also an independent role as a third messenger in the ABA signaling pathway. This study provides a reference for analyzing the potential function of genes in the future research.