Bacterial effectors manipulate plant abscisic acid signaling for creation of an aqueous apoplast

• Published in: Cell host & microbe 2022-04, Vol.30 (4), p.518-529.e6
• Main Authors: Hu, Yezhou, Ding, Yanxia, Cai, Boying, Qin, Xiaohui, Wu, Jingni, Yuan, Minhang, Wan, Shiwei, Zhao, Yang, Xin, Xiu-Fang
• Format: Article
• Language: English
• Subjects: ABA signaling; Abscisic Acid - metabolism; Abscisic Acid - pharmacology; Arabidopsis - microbiology; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; bacterial pathogenesis; Pseudomonas syringae - metabolism; stomatal movement; type III effector; type one protein phosphatase; Water - metabolism; water soaking
• ISSN: 1931-3128; 1934-6069
• DOI: 10.1016/j.chom.2022.02.002

Phytopathogens like Pseudomonas syringae induce “water soaking” in the apoplastic space of plant leaf tissue as a key virulence mechanism. Water soaking is commonly observed in diverse pathosystems, yet the underlying physiological basis remains largely elusive. Here, we show that one of the strong P. syringae water-soaking inducers, AvrE, alters the regulation of abscisic acid (ABA) to induce ABA signaling, stomatal closure, and, thus, water soaking. AvrE binds and inhibits the function of Arabidopsis type one protein phosphatases (TOPPs), which negatively regulate ABA by suppressing SnRK2s, a key node of the ABA signaling pathway. The topp12537 quintuple mutants display significantly enhanced water soaking after P. syringae inoculation, whereas the loss of the ABA pathway dampens P. syringae-induced water soaking and disease. Our study uncovers the hijacking of ABA signaling and stomatal closure by P. syringae effectors as key mechanisms of disease susceptibility. [Display omitted] •P. syringae infection induces ABA responses and stomatal closure in the plant leaf•P. syringae effector AvrE targets TOPP proteins in Arabidopsis to alter ABA signaling•AvrE induces ABA accumulation and stomatal closure for water soaking•ABA pathway is indispensable for P. syringae-induced water soaking and disease Pseudomonas syringae induces “water soaking” in the apoplastic space of the plant leaf to facilitate infection. Hu et al. discover the underlying mechanisms, revealing that P. syringae effector AvrE targets TOPP proteins to perturb the plant abscisic acid pathway and induce stomatal movement, thus creating this aqueous environment.