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Lack of RsmA-mediated control results in constant hypervirulence, cell elongation, and hyperflagellation in

Viia Kõiv1, Liis Andresen, Martin Broberg

  • 1University of Tartu, Institute of Molecular and CellBiology, Tartu, Estonia. pontu55@hot.ee

Plos One
|February 2, 2013
PubMed

Insights

The RsmA regulator in Pectobacterium wasabiae controls virulence. Its absence leads to increased virulence factor production and swarming, but decreased growth and host survival.

Area of Science:

  • Microbiology
  • Plant Pathology
  • Molecular Biology

Background:

  • The posttranscriptional regulator RsmA influences virulence in Pectobacterium pathogens.
  • RsmA controls cell motility and the production of plant cell wall degrading enzymes (PCWDE).

Purpose of the Study:

  • Investigate the physiological role of RsmA-mediated gene regulation in Pectobacterium wasabiae.
  • Determine the impact of rsmA gene disruption on bacterial growth, virulence, and gene expression.

Main Methods:

  • Gene disruption of rsmA in Pectobacterium wasabiae SCC3193.
  • Genome-wide microarray analysis to compare mRNA levels between mutant and wild-type strains.
  • In vitro assays for swarming and PCWDE production.
  • Virulence experiments in potato tubers.

Main Results:

  • rsmA disruption decreased growth rate by 3-fold and increased virulence.
  • Genes for virulence factors, motility, and secretion systems were upregulated in the rsmA mutant.
  • The rsmA mutant showed increased swarming and PCWDE production but reduced host survival and fitness.

Conclusions:

  • Absence of RsmA induces a constitutively infective phenotype with high virulence factor expression and swarming.
  • Loss of RsmA control over energy-intensive processes likely reduces growth rate and fitness.
  • A link between swarming and virulence in plant pathogens is suggested.

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