The expression profiling of the CsPYL, CsPP2C and CsSnRK2 gene families during fruit development and drought stress in cucumber

The abscisic acid (ABA) signal transduction core components in plants include the ABA receptors (PYR/PYL/RCARs), the group A type 2C protein phosphatases (PP2Cs) and the subclass III SNF1-related protein kinases 2 (SnRK2s). In this study, via homology cloning, three CsPYLs, four CsPP2Cs and two CsSnRK2s partial cDNAs were obtained in cucumber (Cucumis sativus). In silico analysis results indicated that all CsPYL, CsPP2C, and CsSnRK2 genes obtained are homologous to Arabidopsis AtPYL, AtPP2C, and AtSnRK2 genes, respectively. Based on phylogenetic analysis, only CsPP2C2 and CsSnRK2.2 belonged to group A PP2C and subclass III SnRK2, respectively, and may involve in ABA signal transduction. During cucumber fruit development and ripening, CsPYL2 and CsPP2C2 were highly expressed and both reached their peak value at 27 DAF, at which stage the ABA content was also at its highest level, which indicated that the CsPYL2 and CsPP2C2 may involve in transducing ABA signal in fruit and regulating fruit development and ripening. Under drought stress condition in cucumber seedlings, CsPYL1, CsPYL2, CsPP2C2 and CsSnKR2.2 were sensitive and up-regulated in root, stem and leaf; meanwhile, CsPYL3 showed a low sensitivity and were down-regulated in root and stem.