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Poster

Session: Session 2 Presenting Authors at Posters (Odds)

P-353 - Investigating cues for activation of Type VI secretion system can provide insights into niche adaption of foliar pathogen, Xanthomonas perforans

Wednesday, July 16, 2025
13:30 - 15:15  
Location: Confex Hall 3
Plant microbiota functions and intermicrobial interactions

    Presenting Author(s)

  • PG

    Palash Ghosh (he/him/his)

    Ph.D. Student
    Auburn University
    Auburn, Alabama, United States

    • Author(s)

  • DB

    Destiny Brokaw

    Auburn University
    Auburn, Alabama, United States

  • NP

    Neha Potnis

    Associate Professor
    Auburn University - Auburn University, AL
    Auburn University, Alabama, United States

The Type VI Secretion System (T6SS) is known as a nanomolecular machinery that functions like a molecular crossbow to delivers effector proteins or toxins into neighboring prokaryotic and eukaryotic cells Xanthomonas perforans (Xp) which causes bacterial leaf spot disease in tomato and pepper harbors two T6SS clusters (designated as i3* and i3***), yet the role of T6SS clusters of Xp in niche adaptation remains poorly understood. We hypothesized that Xp employs T6SS clusters to interact with specific members of the phyllosphere, and to alleviate abiotic stressors. To investigate this, we examined activation of T6SS clusters using promoter-reporter fusion constructs, containing promoter of vipB core gene of each T6SS fused to GFP reporter. We observed that while there is a basal level constitutive expression of both clusters, specific phyllosphere residents can induce higher expression levels of a specific cluster. We characterized outcome of in vitro interactions of phyllosphere residents with Xp as inhibitory to Xp or to the resident member and observed that T6SS can also be induced in Xp during survival mode when Xp is inhibited by phyllosphere resident.  In addition, pH, salinity, and antibiotic exposure also triggered T6SS clusters, suggesting that damage to the cell membrane may also trigger T6SS expression in Xp. These results highlight the vigilance and defensive capabilities of T6SS in Xp, allowing it to counteract stresses encountered during epiphytic colonization.