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Poster

Session: Session 2 Presenting Authors at Posters (Evens)

P-362 - Molecular mechanisms used by diazotrophic endophytes of Populus at a community level

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

    Presenting Author(s)

  • EG

    Emma Gomez-Rivas

    PhD Candidate
    University of Washington
    Seattle, WA, USA

    • Author(s)

  • SD

    Sharon Doty

    PI
    University of Washington
    Seattle, Washington, United States

  • RT

    Robert Tournay

    Postdoc
    University of Washington
    Seattle, Washington, United States

  • AS

    Andrew Sher

    Scientist
    University of Washington
    Seattle, Washington, United States

  • JA

    Jayde Aufrecht

    Postdoc
    Pacific Northwest National Lab
    Richland, Washington, United States

  • AA

    Amir Ahkami

    Scientist
    Pacific Northwest National Lab
    Richland, Washington, United States

  • DH

    Daisy Herrera

    Technician
    Pacific Northwest National Lab
    Richland, Washington, United States


The goal of this project is to investigate how community-wide interactions within a population of a single endophyte and between different strains contribute to overall productivity of nitrogen (N) fixing diazotrophs. We showed that while only a small fraction of the strain Burkholderia vietnamesis WPB actively express nitrogenase in N-limited culture (10%), other cells produce metabolites that indicate their role in providing energy and a suitable microenvironment for N-fixing cells. Additionally, WPB is 30x more likely to express nitrogenase when found in cellular aggregates rather than in individually dispersed cells, indicating that quorum sensing may be involved. When roots of P. trichocarpa were inoculated with fluorescently tagged WPB and imaged via confocal microscopy, cells expressing nitrogenase were found in novel intracellular structures we termed ‘nitrosomes’, which are under current investigation. We also showed via acetylene reduction assay that there is a significant increase in nitrogenase activity of several of our diazotrophs when co-inoculated in N-limited media with non-diazotrophic ‘helper’ strains. Subsequent assays showed that some strains required cell contact to benefit from this effect while others did not, indicating that various mechanisms may be at play. Future studies include identifying the mechanisms involved in this effect via metabolomic studies and further defining this phenomenon in-planta using fluorescent microscopy.