Development of microsatellite markers from the transcriptome of Erysiphe necator for analysing population structure in North America and Europe

Authors

  • O. Frenkel,

    1. Department of Plant Pathology & Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
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    • Present address: Department of Plant Pathology, Agricultural Research Organization, The Volcani Center, POB 6, Bet-Dagan 50250, Israel.

  • I. Portillo,

    1. Dipartimento di Protezione e Valorizzazione Agro-Alimentare, Università degli Studi di Bologna, Viale Fanin 46, 40100 Bologna, Italy
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  • M. T. Brewer,

    1. Department of Plant Pathology & Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
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    • Present address: Department of Plant Pathology, University of Georgia, Athens, GA 30602, USA.

  • J. P. Péros,

    1. Institut National de la Recherche Agronomique, UMR 1334, Equipe DAVEM, 2 place Viala, 34060 Montpellier, France
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  • L. Cadle-Davidson,

    1. United States Department of Agriculture–Agricultural Research Service, Grape Genetics Research Unit, Geneva, NY 14456, USA
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  • M. G. Milgroom

    Corresponding author
    1. Department of Plant Pathology & Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
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E-mail: mgm5@cornell.edu

Abstract

Transcriptome sequences of the grape powdery mildew fungus Erysiphe necator were used to develop microsatellite markers (EST-SSRs) to study its relatively unexplored population structure in its centre of diversity in eastern North America. Screening the transcriptome sequences revealed 116 contigs with candidate microsatellites, from which 11 polymorphic microsatellite markers were developed from 31 markers tested. Eight of these markers were used to genotype isolates from different regions and hosts in the eastern USA and compare them to samples from southern France and Italy. Genetic diversity in the eastern USA is much greater than in Europe. Bayesian cluster analyses showed that 10 isolates from North America have high affinities with, but differ from, European group A; these are referred to as A-like isolates. No isolates with close affinity to European group B were found in the eastern USA. Bayesian analyses also detected genetic differentiation between isolates from Vitis rotundifolia and isolates from other Vitis hosts. Genetic differentiation detected between the northeastern and southeastern USA was mostly attributable to the A-like isolates in the southeast, which are significantly more aggressive than the other populations. This research demonstrates that transcriptome sequencing of fungal pathogens is useful for developing genetic markers in protein-coding regions and highlights the role of these markers in population biology studies of E. necator.

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