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Concurrent Session

Session: Concurrent Session: Plant microbiota functions and intermicrobial interactions

Genes involved in manipulating the host growth-defense tradeoff by root-associated bacteria

Wednesday, July 16, 2025
15:55 - 16:15  
Location: Confex Hall 1+2

    Author(s)

  • JH

    Jana Hucklenbroich

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

  • ZP

    Zoe Prockl

    Faculty of Science, Hokkaido University
    Cologne, Nordrhein-Westfalen, Germany

  • FR

    Fiqih Ramadhan

    Faculty of Science, Hokkaido University
    Sapporo, Hokkaido, Japan

  • SP

    Silvina Perin

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

    • Presenting Author(s)

  • RN

    Ryohei Thomas Nakano

    Faculty of Science, Hokkaido University
    Sapporo, Hokkaido, Japan

    • Author(s)

  • TS

    Tomohisa Shimasaki

    Faculty of Science, Hokkaido University
    Sapporo, Hokkaido, Japan

The plant growth-defense tradeoff is a well-documented phenomenon in which chronic activation of plant immunity inhibits growth. This tradeoff has significant ecological and agricultural implications, yet its modulation by root-associated commensal bacteria remains largely unexplored. We previously identified bacterial strains capable of mitigating this tradeoff, allowing sustained plant growth even under prolonged immune activation by the microbe-associated molecular pattern (MAMP) flg22 or the danger-associated molecular pattern (DAMP) AtPep1. Here, we investigate the genetic basis underlying this bacterial suppression of pattern-triggered growth inhibition. Using a forward genetic screen based on mTn5-mediated random mutagenesis, we identified six bacterial mutants defective in this suppressive activity, most of which retained their ability to colonize host roots. Among them, one mutant harbored a transposon insertion in AhcY, a gene encoding adenosylhomocysteinase, an enzyme involved in the methionine metabolic cycle. Functional analysis revealed that this metabolic pathway plays a critical role in regulating the bacterial ability to influence the plant growth-defense tradeoff. We hypothesize that disruptions in the methionine cycle alter bacterial DNA methylation patterns, leading to transcriptional changes that suppress the production and/or secretion of the active compound responsible for tradeoff manipulation.