Polymorphism at the ribosomal DNA ITS and its relation to postglacial re-colonization routes of the Perigord truffle Tuber melanosporum

Authors

  • Claude Murat,

    1. UMR INRA/UHP 1136 ‘Interactions Arbres/Micro-Organismes’, Centre INRA de Nancy, F-54280 Champenoux, France;
    2. Dipartimento di Biologia Vegetale dell′Università di Torino, Viale Mattioli I-10125 Torino, Italy;
    3. These authors contributed equally to this work;
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  • Jesús Díez,

    1. UMR INRA/UHP 1136 ‘Interactions Arbres/Micro-Organismes’, Centre INRA de Nancy, F-54280 Champenoux, France;
    2. Departamento de Biología Vegetal, Universidad de Alcalá, E-28871 Alcalá de Henares, Spain;
    3. These authors contributed equally to this work;
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  • Patricia Luis,

    1. UMR INRA/UHP 1136 ‘Interactions Arbres/Micro-Organismes’, Centre INRA de Nancy, F-54280 Champenoux, France;
    2. Present address: Institut für Botanik – Terrestrische Ökologie, Universität Leipzig – Johannisallee 21–23 D-04103 Leipzig, Germany
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  • Christine Delaruelle,

    1. UMR INRA/UHP 1136 ‘Interactions Arbres/Micro-Organismes’, Centre INRA de Nancy, F-54280 Champenoux, France;
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  • Chantal Dupré,

    1. UMR 1095 INRA-UBP ‘Amélioration et Santé des Plantes’, Site de Crouelle, 234 avenue du Brézet, F-63039 Clermont-Ferrand Cedex 2, France;
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  • Gérard Chevalier,

    1. UMR 1095 INRA-UBP ‘Amélioration et Santé des Plantes’, Site de Crouelle, 234 avenue du Brézet, F-63039 Clermont-Ferrand Cedex 2, France;
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  • Paola Bonfante,

    1. Dipartimento di Biologia Vegetale dell′Università di Torino, Viale Mattioli I-10125 Torino, Italy;
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  • Francis Martin

    Corresponding author
    1. UMR INRA/UHP 1136 ‘Interactions Arbres/Micro-Organismes’, Centre INRA de Nancy, F-54280 Champenoux, France;
      Author for correspondence: Francis Martin Tel: +33 383 39 40 80 Fax: +33 383 39 40 69 Email: fmartin@nancy.inra.fr
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Author for correspondence: Francis Martin Tel: +33 383 39 40 80 Fax: +33 383 39 40 69 Email: fmartin@nancy.inra.fr

Summary

  • • Glaciations and postglacial migrations are major factors responsible for the present patterns of genetic variation we see in natural populations in Europe. For ectomycorrhizal fungi, escape from refugia can only follow range expansion by their specific hosts.
  • • To infer phylogeographic relationships within Tuber melanosporum, sequences of internal transcribed spacers (ITS) and the 5.8S coding region of the ribosomal DNA repeat were obtained for 188 individuals sampled over the entire distribution of this species in France, and in north-western Italy and north-eastern Spain.
  • • Ten distinct ITS haplotypes were distinguished, mapped and treated using F- and NST-statistics and nested clade (NCA) analyses. They showed a significant genetic differentiation between regional populations. NCA revealed a geographical association of ITS haplotypes, an old fragmentation into two major groups of populations, which likely colonized regions on different sides of the French Central Massif.
  • • This re-colonization pattern is reminiscent of the one observed for host trees of the Perigord truffle, such as oaks and hazelnut trees. This suggests that host postglacial expansion was one of the major factors that shaped the mycobiont population structure.

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