Transcription factor involved in the regulation of gene (e.g. drought-regulated and flavonoid biosynthetic genes) expression and stomatal movements leading to negative regulation of responses to drought and responses to other physiological stimuli (e.g. light). Restricted to stomatal guard cells. Mostly expressed in leaves, cotyledons, hypocotyls, seeds and ripened berry skins. During seed development, gradually down-regulated towards the onset of ripening (veraison). During berry skin development, dramatic decrease to full repression at veraison, followed by a slight increase towards ripening. In flowers, barely detectable in stamens, at the interface of filaments and anthers. Repressed by abscisic acid (ABA) and osmotic stress (salt stress).