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Poster

Session: Session 2 Presenting Authors at Posters (Evens)

P-336 - Fungal Glycoside Hydrolases shape the Leaf Microbiome and mediate Interkingdom Microbial Antagonism

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

    Presenting Author(s)

  • ZS

    Zarah Sorger

    PhD Candidate
    University of Cologne
    Cologne, Nordrhein-Westfalen, Germany

    • Author(s)

  • SD

    Sarah Daher

    PhD Candidate
    University of Cologne
    Cologne, Nordrhein-Westfalen, Germany

  • KB

    Klara Beier-Heuchert

    University of Cologne
    Cologne, Nordrhein-Westfalen, Germany

  • PS

    Priyamedha Sengupta

    University of Cologne
    Cologne, Nordrhein-Westfalen, Germany

  • KE

    Katharina Eitzen

    University of Cologne
    Cologne, Nordrhein-Westfalen, Germany

  • EK

    Eric Kemen

    Centre of Plant Molecular Biology (ZMBP), University of Tübingen
    Tuebingen, Baden-Wurttemberg, Germany

  • JP

    Jane Parker

    Senior Group Leader
    Department of Plant-Microbe Interactions, Max-Planck Institute for Plant Breeding Research
    Cologne, GERMANY

  • GD

    Gunther Doehlemann

    Professor
    University of Cologne
    Cologne, Nordrhein-Westfalen, Germany


Plants are colonized by diverse microorganisms that interact in complex networks. A network analysis of the leaf microbiome of Arabidopsis thaliana showed that most interactions are negative. We previously identified the beneficial yeast Moesziomyces bullatus ex Albugo on Arabidopsis (MbA), which inhibits the pathogenic oomycete A. laibachii, reducing its virulence. We discovered that a glycoside hydrolase (GH25) secreted by MbA plays a key role in this antagonism.



Here, we analyzed the function of glycoside hydrolase 25 in plant-colonizing fungi of opposing lifestyles, i.e. the beneficial yeast MbA and the pathogenic smut fungus U. maydis. We found GH25 to modulate the microbial community associated with A. laibachii, inhibiting specific bacteria that promote oomycete growth. These bacteria, in turn, can override GH25 mediated inhibition of A. laibachii, suggesting an interkingdom antagonism between yeast, oomycete, and bacteria.



We also found that GH25 targets health-relevant bacteria in the maize phyllosphere. Consistently, gene deletion reduced U. maydis virulence, similar to the loss of a previously identified antimicrobial ribotoxin Ribo1. Both GH25 and Ribo1 act as antimicrobial effectors, crucial for U. maydis infection but have distinct bacterial targets. Our findings highlight the role of glycoside hydrolases in microbial niche competition, demonstrating their importance for fungal colonization in the phyllosphere.