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Increasing aggressiveness of the phytopathogenic bacteria Ralstonia solanacearum by gene acquisition : [O1-08, Abstract]

Coupat-Goutaland Bénédicte, Guidot Alice, Bernillon D., Prior Philippe, Nesme Xavier, Bertolla Franck. 2010. Increasing aggressiveness of the phytopathogenic bacteria Ralstonia solanacearum by gene acquisition : [O1-08, Abstract]. In : Proceedings of the 12th International Conference on Plant Pathogenic Bacteria : programme, abstracts, list of participants. INRA, Université de la Réunion, IRD. s.l. : s.n., 24. International Conference on Plant Pathogenic Bacteria. 12, Saint-Denis, Réunion, 7 Juin 2010/11 Juin 2010.

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Résumé : Ralstonia solanacearum, the causal agent of bacterial wilt disease on many crops including Solanaceae and Musaceae, is a complex of species (i.e. phylotypes). Along to this high diversity, R. solanacearum is also characterized by a high genetic plasticity, both being suspected to be involved in its rapid pathogenic evolution as well as in its large host range (more than 450 plant species). The R. solanacearum genome plasticity is evidenced by the presence of "ACUR" (alternative codon usage region) in their genomes, and by the ability of all species tested up to now to capture and integrate free exogenous DNA from the environment (1). In this context, we studied importance and role of gene transfers and natural transformation for the evolution of the pathogenicity amongst members of the species complex. In this work, we measured frequency and size of genomic regions that can be exchanged during inter-phylotype natural transformations, by analyzing more specifically the mobility of regions containing type Ill effectors or ACUR regions suspected to originate from bacteria other out of the R. solanacearum complex. Extent and number of transfer events were also evaluated by using selective antibiotics markers as well as by comparative genomics with DNA microarrays (2). Transfers of large DNA regions, > 80 kb, were detected between phylotypes, among which 50 kb were gene replacements that induced single nucleotide polymorphisms (SNPs), and 30 kb corresponding to the acquisition of 20 new genes with 3 potentially involved in pathogenicity. In order to determine whether the acquisition of such a region rich in pathogenicity genes could alter the recipient pathogenicity, we then compared tomato responses to inoculation of wild type and transformant strains. Very interestingly, we found that the transformant strain became much more aggressive than its wild parent, suggesting that such inter-species gene transfers may play a great role in the rapid emergence of new pathotypes of R. solanacearum.

Classification Agris : H20 - Maladies des plantes

Auteurs et affiliations

  • Coupat-Goutaland Bénédicte, CNRS (FRA)
  • Guidot Alice, INRA (FRA)
  • Bernillon D., CNRS (FRA)
  • Prior Philippe, CIRAD-BIOS-UMR PVBMT (REU)
  • Nesme Xavier, CNRS (FRA)
  • Bertolla Franck, CNRS (FRA)

Autres liens de la publication

Source : Cirad - Agritrop (https://agritrop.cirad.fr/557095/)

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