Detection of phytopathogenic Xanthomonads via a novel perception mechanism in Arabidopsis thaliana

• Applicant: Professor Dr. Georg Felix
• Subject Area: Organismic Interactions, Chemical Ecology and Microbiomes of Plant Systems ; Plant Genetics and Genomics ; Plant Breeding and Plant Pathology
• Term: from 2020 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 441178209

Many bacterial species of the genus Xanthomonas are serious pathogens for crop plants. In our previous work we detected that, as part of their defense system, the model plant Arabidopsis has means to detect Xanthomonas via the pattern recognition receptor ReMAX/RLP1 that detects a specific, but yet unidentified, protein from Xanthomonas bacteria. In our ongoing attempts to purify and identify this protein, we detected a second factor that is perceived by Arabidopsis in a ReMAX/RLP1 independent way. Purification of this second factor proved easier and allowed its identification as a subtilase enzyme secreted by the Xanthomonas bacteria. Our results, so far, show that it is not the subtilase molecule itself, which is sensed. Rather, our evidence shows that the proteolytic activity of the bacterial subtilase processes a protein exported by the plant cells to a smaller polypeptide that triggers typical defense responses in plant cells via a specific surface receptor. In order to characterize this novel molecular pathogen perception mechanism, the primary aims of this project are the identification of this plant factor, termed SAMP for subtilase activated molecular pattern, and its cognate plant receptor.

• DFG Programme: Research Grants