The ABA receptor-like gene VyPYL9 from drought-resistance wild grapevine confers drought tolerance and ABA hypersensitivity in Arabidopsis

The PYR/PYL/RCAR (hereafter referred to PYLs) proteins, which act as abscisic acid (ABA) receptors, have been reported to play a crucial role in response to drought stress. In this study, we used a drought-resistant accession of the wild Chinese grapevine, Vitis yeshanensis-'Yanshan-1', as a model to understand the function of PYLs in grape and other fruit crops. We cloned six PYL genes from V. yeshanensis. Phylogenetic analysis showed that the encoded proteins could be classified into three subfamilies. All six grapevine PYL proteins contained conserved amino acids at positions implicated in 'gate-and-latch' mechanism of ABA binding and in the interaction with PP2C proteins. Gene expression profiles of VyPYLs in various tissues of 'Yanshan-1' plants revealed they were relatively strongly expressed in old leaves compared to young leaves. Analysis of the subcellular localization of the VyPYL proteins showed that they were localized in the cytoplasm and the nucleus. Yeast two-hybrid assays revealed that six VyPYL proteins selectively interacted with three VyPP2C proteins in an ABA-dependent or ABA-independent manner. Expression of one of the genes, VyPYL9, was induced by exogenous ABA and drought conditions. Heterologous expression of VyPYL9 in Arabidopsis enhanced ABA sensitivity during seed germination and primary root growth. Moreover, VyPYL9-expressing Arabidopsis plants showed enhanced drought tolerance, and this was associated with decreased water loss and increased activity of antioxidant defense systems. In addition, we found that ABA promoted leaf senescence in Arabidopsis plants expressing VyPYL9. Taken together, our results suggest that VyPYL9 may be involved in response of grapevine to drought stress via the ABA signaling pathway. Key message VyPYL9-expressing Arabidopsis plants showed enhanced drought tolerance, and this was associated with decreased water loss and increased activity of antioxidant defense systems. In addition, we found that ABA promoted leaf senescence in Arabidopsis plants expressing VyPYL9.