Repressor of the abscisic acid (ABA) signaling pathway that regulates numerous ABA responses, such as stomatal closure, osmotic water permeability of the plasma membrane (Pos), high light stress, response to glucose, seed germination and inhibition of vegetative growth. During the stomatal closure regulation, modulates the inward calcium-channel permeability as well as H2O2 and oxidative burst in response to ABA and dehydration. Represses GHR1 and, to some extent, SRK2E/OST1, kinases involved in the regulation of SLAC1-dependent stomatal closure. Controls negatively fibrillin that is involved in mediating ABA-induced photoprotection. May be implicated in ABA content regulation. Involved in acquired thermotolerance of root growth and seedling survival. Required for the Erwinia amylovora harpin-induced (HrpN) drought tolerance. Involved in the hydrotropic response.