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Tomato Root Transformation Followed by Inoculation with Ralstonia Solanacearum for Straightforward Genetic Analysis of Bacterial Wilt Disease
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Published on: March 11, 2020

Natural transformation-based foreign DNA acquisition in a Ralstonia solanacearum mutS mutant

Anne Mercier1, Franck Bertolla, Eugénie Passelègue-Robe

  • 1Université de Lyon, F-69003 Lyon, France.

Research in Microbiology
|July 10, 2007
PubMed

Insights

Mutator strains with defective methyl-mismatch repair (MMR) systems enhance bacterial adaptation. In Ralstonia solanacearum, mutS inactivation significantly increased DNA transformation but did not lead to genetic transformation by transgenic plant DNA.

Area of Science:

  • Microbiology
  • Bacterial Genetics
  • Horizontal Gene Transfer

Background:

  • Defective methyl-mismatch repair (MMR) systems in mutator strains are crucial for bacterial adaptation.
  • Ralstonia solanacearum is a significant phytopathogenic bacterium.

Purpose of the Study:

  • To investigate the impact of mutS inactivation on foreign DNA acquisition via natural transformation in Ralstonia solanacearum.
  • To assess the potential for horizontal gene transfer (HGT) from genetically modified plants to Ralstonia solanacearum.

Main Methods:

  • Generated a mutS mutant of Ralstonia solanacearum to assess its mutator phenotype.
  • Conducted transformation experiments to quantify intra- and interspecific DNA transfers.
  • Evaluated the fitness of the mutator strain in soil and plant environments.
  • Performed in vitro and in planta tests to detect genetic transformation by transgenic plant DNA.

Main Results:

  • The mutS mutant exhibited 33- to 60-fold higher spontaneous mutation frequencies, confirming its mutator phenotype.
  • Intra- and interspecific DNA transfers increased by up to 89-fold in the mutS mutant.
  • The mutator strain showed comparable fitness and competitiveness to the wild-type strain in soil and tomato plants.
  • Despite enhanced HGT capacity and survival, no genetic transformation by transgenic plant DNA was observed.

Conclusions:

  • Mutator strains with defective MMR systems, like the R. solanacearum mutS mutant, exhibit increased transformation frequencies.
  • The study demonstrates that despite high HGT potential, R. solanacearum does not acquire genetic material from transgenic plants under tested conditions.
  • This finding has implications for understanding gene flow between bacteria and genetically modified organisms.

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