VAMP711 Is Required for Abscisic Acid-Mediated Inhibition of Plasma Membrane H⁺-ATPase Activity

Abstract

Drought stress is a limiting environmental factor that affects plant growth and development. The plant hormone abscisic acid (ABA) plays an important role in plant drought responses. Previous studies have indicated that ABA inhibits plasma membrane H⁺-ATPase (PM H⁺-ATPase) activity, and the decrease in PM H⁺-ATPase activity promotes stomatal closure under drought stress, thereby reducing water loss. However, the underlying molecular mechanisms are not well understood. In this study, we found that in Arabidopsis (<i>Arabidopsis thaliana</i>), ABA induces an <i>N</i>-ethylmaleimide-sensitive factor attachment protein receptor protein, namely, VESICLE-ASSOCIATED MEMBRANE PROTEIN 711 (VAMP711), to interact with the Arabidopsis PM H⁺-ATPases AHA1 and AHA2. The interaction occurs at their C-termini and inhibits PM H⁺-ATPase activity. Deletion of <i>VAMP711</i> in Arabidopsis results in a higher PM H⁺-ATPase activity and slower stomatal closure in response to ABA and drought treatments. In addition, overexpression of <i>VAMP711</i> partially rescues the drought-sensitive phenotype of <i>ost2-2D</i>, a mutation in <i>AHA1</i> resulting in a constitutive activated PM H⁺-ATPase. Our results demonstrate that VAMP711 is involved in regulating ABA-mediated inhibition of PM H⁺-ATPase activity and stomatal closure in response to drought stress.