The Xanthomonas type-III effector XopS stabilizes CaWRKY40a to regulate defense responses and stomatal immunity in pepper (Capsicum annuum)

• DOI: 10.1093/plcell/koac032
• Publication Date: 2022-01-27T12:13:28Z
• Authors: Margot Raffeiner; Suayib Üstün; Tiziana Guerra; Daniela Spinti; Maria Fitzner; Sophia Sonnewald; Susanne Baldermann; Frederik Börnke
• Keywords: Pseudomonas syringae; Xanthomonas

As a critical part of plant immunity, cells that are attacked by pathogens undergo rapid transcriptional reprogramming to minimize virulence. Many bacterial phytopathogens use type III effector (T3E) proteins interfere with defense responses, including this reprogramming. Here, we show Xanthomonas outer protein S (XopS), T3E campestris pv. vesicatoria (Xcv), interacts and inhibits proteasomal degradation WRKY40, regulator gene expression. Virus-induced silencing WRKY40 in pepper (Capsicum annuum) enhanced tolerance Xcv infection, indicating represses immunity. Stabilization XopS reduces the expression its targets, which include salicylic acid-responsive genes jasmonic acid signaling repressor JAZ8. bacteria lacking display significantly reduced virulence when surface inoculated onto susceptible leaves. delivery Xcv, as well ectopic Arabidopsis thaliana or Nicotiana benthamiana, prevented stomatal closure response biotic elicitors. Silencing N. benthamiana abolished XopS's ability prevent closure. This suggests interferes both preinvasion apoplastic manipulating stability downstream expression, eventually altering phytohormone crosstalk promote pathogen proliferation.