Session: Session 2 Presenting Authors at Posters (Evens)
P-142 - Opening the gates – control of stomatal apertures by the F-box type III effector XopI from the plant-pathogenic bacterium Xanthomonas euvesicatoria
Researcher Martin Luther University Halle-Wittenberg Halle (Saale), Sachsen-Anhalt, Germany
Xanthomonas euvesicatoria, causal agent of bacterial spot disease on pepper and tomato, is a non-vascular pathogen and enters the intercellular spaces of the plant tissue via stomata. Pathogenicity depends on type III effectors (T3E) which are translocated into plant cells and manipulate cellular processes to the pathogen’s benefit. Here, we characterized the function of the T3E XopI and analysed plant interaction partners using yeast two-hybrid assays, pull-down experiments and coimmunoprecipitation. Our data revealed that XopI contributes to disease symptoms and counteracts stomatal closure during plant defense and after induction by the phytohormone abscisic acid. Furthermore, XopI suppresses the increase in reactive oxygen species after recognition of microbe-associated molecular patterns (MAMPs) and complements a Pseudomonas syringae coronatine mutant for stomata opening in Arabidopsis. XopI targets various plant proteins including an ATP binding cassette (ABC) protein, which contributes to MAMP-triggered stomatal closure, the catalase CAT2 and a RAF-like kinase involved in ABA signaling. Additionally, XopI interacts via its F-box motif with SKP1 (S-phase kinase-associated protein 1)-like proteins which are components of SCF (SKP1[S-phase kinase-associated protein 1]/CULLIN1/F-box protein)-type E3 ubiquitin ligases. Our data suggest that XopI acts as adaptor between SKP1 and plant proteins, thus leading to their degradation by the proteasome.
