Skip to main content
ISMPMI Congress 2025 Main banner
Icon Legend
This session is not in your schedule.
This session is in your schedule. Click again to remove it.

Poster

Session: Session 2 Presenting Authors at Posters (Odds)

P-357 - Lipopolysaccharide-Mediated Tailocin Resistance Impairs Bacterial Host Colonization

Wednesday, July 16, 2025
13:30 - 15:15  
Location: Confex Hall 3
Plant microbiota functions and intermicrobial interactions
Understanding the mechanisms involved in microbial competition is fundamental to the development of pathogen-specific control strategies. Pathogenic bacteria produce tailocins (phage-derived structures) that specifically target closely related strains via receptors on the bacterial membrane (lipopolysaccharides, LPS). A large study on Pseudomonas viridiflava strains isolated from natural Arabidopsis thaliana accessions showed that tailocin-resistant strains are rare in nature, but the evolutionary constraints that limit the emergence of tailocin resistance are largely unknown. RB-TnSeq screening of a mutagenesis library of a P. viridiflava strain revealed that mutations disrupting part of LPS (O-antigen) synthesis conferred tailocin resistance but were associated with a fitness tradeoff in planta. Further analysis of O-antigen-deficient single mutants confirmed their inability to cause disease, as evidenced by reduced bacterial growth and symptom development. To investigate the mechanisms underlying this tradeoff, we characterized the membrane permeability of these strains and their sensitivity to osmotic stress. Additionally, we purified LPS from these mutants and examined their ability to induce plant immunity, focusing on reactive oxygen species bursts and seedling growth inhibition. Our current hypothesis is that the evolution of tailocin resistance results in LPS modifications that compromise the overall state of the membrane and increase sensitivity to plant immunity.