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Réponse adaptative des populations de Phytophthora infestans, agent du mildiou de la pomme de terre, au déploiement en culture de son hôte Solanum tuberosum

Abstract : Understanding the consequences of selection pressure by host plants on pathogen population structures is crucial for the effective management of durable resistance to plant diseases. The objectives of this work were i) to assess the impact of selection on the phenotypic and genotypic structure of the local pathogen population of Phytophthora infestans, the causal agent of potato late blight, as exerted by hosts with various levels of resistance; ii) to determine if recurrent selection pressure applied by prevalent cultivars in different potato production areas led to local adaptation of P. infestans populations; and iii) to test the hypothesis of a trade-off between aggressiveness during the epidemic phase of the disease and the over-winter survival capacity in clonal P. infestans populations. Our results showed that selection by host applies on both qualitative (virulence) and quantitative (aggressiveness) components of pathogenicity. The large variation in aggressiveness allowed adaptation of P. infestans populations, which led to the erosion of partial resistance. French P. infestans populations proved to be adapted to the cultivar prevalent nationally (Bintje), but not to locally prevalent cultivars. Local adaptation takes place in this system, but was detectable only on a very large spatial scale, for populations isolated geographically. Our results also showed that during winter survival there was no counter-selection of the most aggressive strains by over-mortality of infected tubers. This work highlights the importance of considering all the evolutionary forces in order to describe and understand the adaptive response of pathogen populations. In the future, modelling of demogenetic processes will allow the development and validation of effective strategies for resistance management.
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https://tel.archives-ouvertes.fr/tel-00133363
Contributor : Josselin Montarry <>
Submitted on : Monday, February 26, 2007 - 9:40:21 AM
Last modification on : Friday, October 23, 2020 - 4:37:38 PM
Long-term archiving on: : Wednesday, April 7, 2010 - 12:40:56 AM

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  • HAL Id : tel-00133363, version 1
  • PRODINRA : 318608

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Josselin Montarry. Réponse adaptative des populations de Phytophthora infestans, agent du mildiou de la pomme de terre, au déploiement en culture de son hôte Solanum tuberosum. Ecologie, Environnement. Agrocampus - Ecole nationale supérieure d'agronomie de rennes, 2007. Français. ⟨tel-00133363⟩

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