摘要In rice,the Ca2+/calmodulin-dependent protein kinase OsDMI3 is an important positive regulator of absci-sic acid(ABA)signaling.In ABA signaling,H2O2 is required for ABA-induced activation of OsDMI3,which in turn increase H2O2 production.However,how OsDMI3 regulates H2O2 production in ABA signaling remains unknown.Here we show that OsRbohB is the main NADPH oxidase involved in ABA-induced H2O2 produc-tion and ABA-mediated physiological responses.OsDMI3 directly interacts with and phosphorylates OsRbohB at Ser-191,which is OsDMI3-mediated site-specific phosphorylation in ABA signaling.Further analyses revealed that OsDM13-mediated OsRbohB Ser-191 phosphorylation positively regulates the activ-ity of NADPH oxidase and the production of H2O2 in ABA signaling,thereby enhancing the sensitivity of seed germination and root growth to ABA and plant tolerance to water stress and oxidative stress.Moreover,we discovered that the OsDM13-mediated OsRbohB phosphorylation and H2O2 production is dependent on the sucrose non-fermenting 1-related protein kinases SAPK8/9/10,which phosphorylate OsRbohB at Ser-140 in ABA signaling.Taken together,these results not only reveal an important regulatory mechanism that directly activates Rboh for ABA-induced H2O2 production but also uncover the importance of this regula-tory mechanism in ABA signaling.