Identification of the abscisic acid receptor VvPYL1 in Vitis vinifera.

The phytohormone abscisic acid (ABA) plays a central role in many developmental processes and in responses to several abiotic stresses. Identification of the ABA receptor is a first step towards understanding ABA signalling. In this study, using homology analysis, we cloned three genes, named VvPYL1, VvPYL2 and VvPYL3, from Vitis vinifera. An isothermal titration calorimetry assay suggested that VvPYL1 could bind to ABA. A phosphatase activity assay demonstrated that VvPYL1 inhibits phosphatase activity of ABI1, a negative regulator of ABA signalling, in the presence of ABA. Subcellular localisation demonstrates that VvPYL1 is distributed in both the nucleus and cytosol, which is similar to the subcellular localisation of ABA receptors in Arabidopsis. We therefore conclude that VvPYL1 is an ABA receptor that modulates ABA signalling by inhibiting type 2C protein phosphatases (PP2Cs).