biostudies-literaturePfeilmeier SEidgenössische Technische Hochschule Zürich (Federal Institute of Technology Zurich)Eidgenössische Technische Hochschule ZürichSwiss National Science FoundationDeutsche ForschungsgemeinschaftDeutsche Forschungsgemeinschaft (German Research Foundation)136-149https://www.ebi.ac.uk/biostudies/studies/S-EPMC10769872biostudies-literatureUnknown9(1)In healthy plants, the innate immune system contributes to maintenance of microbiota homoeostasis, while disease can be associated with microbiome perturbation or dysbiosis, and enrichment of opportunistic plant pathogens like Xanthomonas. It is currently unclear whether the microbiota change occurs independently of the opportunistic pathogens or is caused by the latter. Here we tested if protein export through the type-2 secretion system (T2SS) by Xanthomonas causes microbiome dysbiosis in Arabidopsis thaliana in immunocompromised plants. We found that Xanthomonas strains secrete a cocktail of plant cell wall-degrading enzymes that promote Xanthomonas growth during infection. Disease severity and leaf tissue degradation were increased in A. thaliana mutants lacking the NADPH oxidase RBOHDNature microbiologyLeaf microbiome dysbiosis triggered by T2SS-dependent enzyme secretion from opportunistic Xanthomonas pathogens.PMC1076987218057551NF40_180575DECRyPT, no. SPP2125Career Seed AwardPetti GCWolf SOte MGabelein CGVorholt JAPfeilmeier SKirner PPestalozzi CMWerz AKeppler AHemmerle LBortfeld-Miller MfalseLeaf microbiome dysbiosis triggered by T2SS-dependent enzyme secretion from opportunistic Xanthomonas pathogens.In healthy plants, the innate immune system contributes to maintenance of microbiota homoeostasis, while disease can be associated with microbiome perturbation or dysbiosis, and enrichment of opportunistic plant pathogens like Xanthomonas. It is currently unclear whether the microbiota change occurs independently of the opportunistic pathogens or is caused by the latter. Here we tested if protein export through the type-2 secretion system (T2SS) by Xanthomonas causes microbiome dysbiosis in Arabidopsis thaliana in immunocompromised plants. We found that Xanthomonas strains secrete a cocktail of plant cell wall-degrading enzymes that promote Xanthomonas growth during infection. Disease severity and leaf tissue degradation were increased in A. thaliana mutants lacking the NADPH oxidase RBOHD2024-01-01T00:00:00Z2024 Jan2026-07-15T00:10:40.543Z2026-06-28T03:05:35.698ZS-EPMC107698723817262010.1038/s41564-023-01555-z