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L'etude de la pathologie de Xanthomonas campestris et de la structure génétique de ses pathovars a permis l'amélioration de la détection du pathogéne dans les semences de Brassicacées

Abstract : Xanthomonas campestris causes diseases on Brassicaceae family including black rot that is considered as the most important diseases of cruciferous plant. This bacterial species groups six pathovars defined according to the type of symptoms that they induce to the host plant from which they were isolated and according to their host range. However doubts have been expressed about the synonymy of some pathovars within X. campestris. It has been necessary to identify pathovars without ambiguity in order to improve strategies against these pathogens. Although sources of contamination are various, seeds constitute the primary inoculum and their sanitary control thus appears as the most efficient disease control strategy. Our objectives have been to clarify the pathogenicity and the genetic structure of the species then to propose a new diagnostic tool that permits the fast and valuable detection of viable X. campestris in seeds. Pathogenicity study of X. campestris species revealed the existence of only three pathovars that can induce disease, X. c. pv. campestris causes the black rot disease, X. c. pv. raphani induces the leaf spots disease and X. c. pv. incanae causes the bacterial blight of garden Stocks. We discussed on the Xanthomonas genus taxonomy based on MLSA data. Our genetic analysis shows how particularly complex and polymorphic is X. campestris. This diversity is the consequence of two evolutionary forces, recombination and mutation, with equally importance. However, this species keeps a clonality structure owing to a tightly host communality within Brassicaceae host. Pathovars are not genetic lineage, but there are not shuffled and share close sequences. We have set up a detection method of viable X. campestris in seeds by BIO-PCR. The BIO-PCR can detect until 10 ufc/ml in seed extract.
keyword : microbiology
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https://tel.archives-ouvertes.fr/tel-00345821
Contributor : Anne-Marie Plé <>
Submitted on : Wednesday, December 10, 2008 - 10:25:18 AM
Last modification on : Tuesday, March 17, 2020 - 3:11:20 AM
Long-term archiving on: : Monday, June 7, 2010 - 9:19:41 PM

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  • HAL Id : tel-00345821, version 1

Citation

Emilie Fargier. L'etude de la pathologie de Xanthomonas campestris et de la structure génétique de ses pathovars a permis l'amélioration de la détection du pathogéne dans les semences de Brassicacées. Biologie cellulaire. Université d'Angers, 2007. Français. ⟨tel-00345821⟩

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