Xanthomonas perforans is a seed-borne hemi-biotrophic pathogen that successfully establishes infection in the phyllosphere of tomato. While the majority of the studies investigating mechanistic basis of pathogenesis have focused on successful apoplastic growth, factors important during asymptomatic colonization in the early stages of disease development are not well understood. In this study, we show that tssM gene of the type VI secretion system cluster i3* (T6SS-i3*) plays a significant role during initial asymptomatic epiphytic colonization at different stages during the life cycle of the pathogen. Mutation in a core gene, tssM of T6SS-i3*, imparted higher aggressiveness to the pathogen, as indicated by higher overall disease severity, higher in planta growth as well as shorter latent infection period compared to the wild-type upon dip-inoculation of 4-5-week-old tomato plants. Contribution of tssM towards aggressiveness was evident during vertical transmission from seed-to-seedling with wild-type showing reduced disease severity as well as lower in planta populations on seedlings compared to the mutant. Presence of functional TssM offered higher epiphytic fitness as well as higher dissemination potential to the pathogen when tested in an experimental setup mimicking transplant house high-humidity conditions. We showed higher osmotolerance being one mechanism by which TssM offers higher epiphytic fitness. Taken together, these data reveal that functional TssM plays a larger role in offering ecological advantage to the pathogen. TssM prolongs the association of hemi-biotrophic pathogen with the host, minimizing overall disease severity, yet facilitating successful dissemination.
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This content will become publicly available on January 11, 2025
Transcriptome profiling of type VI secretion system core gene tssM mutant of Xanthomonas perforans highlights regulators controlling diverse functions ranging from virulence to metabolism
Type VI secretion system (T6SS) is a versatile, contact-dependent contractile nano-weapon in Gram-negative bacteria that fires proteinaceous effector molecules directly into prokaryotic and eukaryotic cells aiding in manipulation of the host and killing of competitors in complex niches. In plant pathogenic xanthomonads, T6SS has been demonstrated to play these diverse roles in individual pathosystems. However, the molecular network underlying the regulation of T6SS is still elusive in
T6SS has received attention due to its significance in mediating interorganismal competition through contact-dependent release of effector molecules into prokaryotic and eukaryotic cells. Reverse-genetic studies have indicated the role of T6SS in virulence in a variety of plant pathogenic bacteria, including the one studied here,
- Award ID(s):
- 1942956
- NSF-PAR ID:
- 10488369
- Editor(s):
- Burbank, Lindsey Price
- Publisher / Repository:
- American Society for Microbiology
- Date Published:
- Journal Name:
- Microbiology Spectrum
- Volume:
- 12
- Issue:
- 1
- ISSN:
- 2165-0497
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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