A plasma membrane receptor kinase, GHR1, mediates abscisic acid- and hydrogen peroxide-regulated stomatal movement in Arabidopsis.

摘要

The plant hormone abscisic acid (ABA) regulates stomatal movement under drought stress, and this regulation requires hydrogen peroxide (H₂O₂). We isolated GUARD CELL HYDROGEN PEROXIDE-RESISTANT1 (GHR1), which encodes a receptor-like kinase localized on the plasma membrane in Arabidopsis thaliana. ghr1 mutants were defective ABA and H₂O₂ induction of stomatal closure. Genetic analysis indicates that GHR1 is a critical early component in ABA signaling. The ghr1 mutation impaired ABA- and H₂O₂-regulated activation of S-type anion currents in guard cells. Furthermore, GHR1 physically interacted with, phosphorylated, and activated the S-type anion channel SLOW ANION CHANNEL-ASSOCIATED1 when coexpressed in Xenopus laevis oocytes, and this activation was inhibited by ABA-INSENSITIVE2 (ABI2) but not ABI1. Our study identifies a critical component in ABA and H₂O₂ signaling that is involved in stomatal movement and resolves a long-standing mystery about the differential functions of ABI1 and ABI2 in this process.