Genotypic diversity of European P. ramorum isolates based on SSR analysis

Kris Van Poucke, Annelies Vercauteren, Martine Maes, Sabine Werres, Kurt Heungens

    Onderzoeksoutput: Hoofdstuk in Boek/Rapport/CongresprocedureC3: Congres abstract


    Genotyping of NA1 isolates of P. ramorum has provided valuable information regarding the introduction, evolution and the pathways of spread of this pathogen in North America. So far, genotyping of European isolates of P. ramorum has only been reported for the Belgian and Spanish populations. Until the epidemic of P. ramorum in larch, the European P. ramorum population was mostly confined to nurseries. This population may have different rates of evolution and selection and different pathways of spread than the NA1 population, which is mostly derived from the natural environment. The objective of this study was to genotype and analyze a wider European collection of P. ramorum, which was in part made possible via the collection of DNA samples as part of the EU COST action FP0801.
    In total, over 1300 samples from 17 European countries were analyzed using seven EU1 polymorphic microsatellite loci. The majority of the samples were collected after 2001 from Rhododendron in nurseries. At least 66 EU1 genotypes were identified. Approximately 64% of the isolates belonged to multilocus genotype EU1MG1, which was present in all countries. Isolates with single repeat shifts in the most variable markers were the second-most abundant and widespread, but at frequencies of less than 6% and in a maximum of 11 countries. As in the NA1 population, the structure of the genotype network is indicative of a clonal expanding population that accumulated microsatellite mutations after a single introduction of the EU1MG1 genotype. The population structure and genetic diversity was similar in most of the countries represented by a sizeable number of samples. The population structure of the UK isolates is unique in that it is characterized by a large subpopulation with a unique mutation in one of the markers, a mutation that presumably arose relatively soon after the introduction of the pathogen in the UK. Based on the finding of unique genotypes in time and space, local evolution followed by national or international spread was also observed for other countries. In general, however, the level of diversity was too small and the amount of (inter)national exchange was too extensive to draw detailed conclusions on the primary origin of specific isolates. There were no clear indications of sexual recombination within the EU1 lineage. Three isolates with highly deviating marker profiles were identified. Further analysis of these isolates revealed that they belong to a new (EU2) lineage, as detailed in a separate report.
    TitelFifth Sudden Oak Death Science Symposium - Meeting Abstracts
    StatusGepubliceerd - 2012
    EvenementFifth Sudden Oak Death Science Symposium - Petaluma, Verenigde Staten van Amerika
    Duur: 19-jun-201222-jun-2012

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