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Poster

Session: Session 2 Presenting Authors at Posters (Evens)

P-310 - Bacteria-Produced Exometabolites Function Additively to Prevent Fungi Dysbiosis in Arabidopsis thaliana Roots

Thursday, July 17, 2025
13:30 - 15:15  
Location: Confex Hall 3
Plant microbiota functions and intermicrobial interactions

    Presenting Author(s)

  • PA

    Priscilla T. Adisa

    Doctoral Researcher
    Max Planck Institute for Plant Breeding Research
    Cologne, Nordrhein-Westfalen, Germany

    • Author(s)

  • GC

    Guillaume Chesneau

    Max Planck Institute for plant breeding research
    Cologne, Nordrhein-Westfalen, Germany

  • AA

    Anna Arroyo

    Max Planck Institute of Plant Breeding Research
    Cologne, Nordrhein-Westfalen, Germany

  • SH

    Stephane Hacquard

    MPIPZ
    Cologne, GERMANY

Plants coexist with microorganisms, including bacterial root commensals which regulate the load, composition and pathogenicity of commensal yet dysbiotic fungal communities, hence, enhancing plant performance. However, mechanisms underlying this bacteria-mediated regulation remain to be elucidated. Here, we aim to systematically unravel the genetic and molecular mechanisms involved. First, we conducted an agar-based screen of 7400 bacteria-fungi interactions to investigate fungi inhibition by bacterial root commensals. Second, we used gnotobiotic systems to assess in planta antifungal and plant protective activity by the top 13 antifungal bacterial strains. Finally, we conducted genetic screenings to define the bacteria-encoded mechanisms preventing fungal dysbiosis. Our findings show kingdom-wide production of antifungal exometabolites with phylogenetic signals in families including Pseudomonadaceae. In-planta assays demonstrate that over 50% of tested strains reduced fungal loads in Arabidopsis roots thereby improving plant performance. Genetic screenings of Pseudomonads and Xanthomonads reveal that strain-specific DAPG and Phenazine as well as family-ubiquitous siderophores function additively in the prevention of fungal dysbiosis. Our study shows that multiple strain-specific and clade-conserved exometabolites with distinct mode of actions are used by individual bacterial strain in regulating fungal-host homeostasis at the root interface thereby promoting plant health.