Evaluating aggressiveness and host range of Alternaria dauci in a controlled environment

Authors

  • C. Boedo,

    1. Université d’Angers, IFR Quasav 149, UMR PaVé A77, UFR Sciences, 2 boulevard Lavoisier
    2. Agrocampus Ouest Centre d’Angers – Institut National d’Horticulture et de Paysage, IFR Quasav 149, UMR GenHort 1259, 2 rue Le Nôtre
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    • Contributed equally to the present work.

  • S. Benichou,

    1. Université d’Angers, IFR Quasav 149, UMR PaVé A77, UFR Sciences, 2 boulevard Lavoisier
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    • Contributed equally to the present work.

  • R. Berruyer,

    1. Université d’Angers, IFR Quasav 149, UMR GenHort 1259, UFR Sciences, 2 boulevard Lavoisier, 49045 Angers Cedex 01, France
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  • S. Bersihand,

    1. Université d’Angers, IFR Quasav 149, UMR PaVé A77, UFR Sciences, 2 boulevard Lavoisier
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  • A. Dongo,

    1. Université d’Angers, IFR Quasav 149, UMR PaVé A77, UFR Sciences, 2 boulevard Lavoisier
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  • P. Simoneau,

    1. Université d’Angers, IFR Quasav 149, UMR PaVé A77, UFR Sciences, 2 boulevard Lavoisier
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  • M. Lecomte,

    1. Agrocampus Ouest Centre d’Angers – Institut National d’Horticulture et de Paysage, IFR Quasav 149, UMR GenHort 1259, 2 rue Le Nôtre
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  • M. Briard,

    1. Agrocampus Ouest Centre d’Angers – Institut National d’Horticulture et de Paysage, IFR Quasav 149, UMR GenHort 1259, 2 rue Le Nôtre
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  • V. Le Clerc,

    1. Agrocampus Ouest Centre d’Angers – Institut National d’Horticulture et de Paysage, IFR Quasav 149, UMR GenHort 1259, 2 rue Le Nôtre
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  • P. Poupard

    Corresponding author
    1. Université d’Angers, IFR Quasav 149, UMR PaVé A77, UFR Sciences, 2 boulevard Lavoisier
      E-mail: pascal.poupard@univ-angers.fr
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E-mail: pascal.poupard@univ-angers.fr

Abstract

The aggressiveness of Alternaria dauci isolates was investigated in greenhouse conditions. Twenty-seven isolates were pre-selected from a large collection to represent high diversity according to geographic or host origins and intergenic spacer (IGS) polymorphism. IGS sequence analysis revealed that isolates were grouped within three different clusters. Eleven isolates were selected and inoculated on a susceptible carrot cultivar. Three criteria (mean lesion number, mean necrotic leaf area and mean disease index) were used to assess the aggressiveness of isolates. Continuous variation in aggressiveness was shown and no clear division into isolate classes was evident. For the host range study, two isolates were inoculated under greenhouse conditions onto nine cultivated Apiaceae species, two wild Daucus species and six cultivated non-Apiaceae species representing six botanical families. Lesions varying in severity were observed on all dicot species (Apiaceae and non-Apiaceae), but no symptoms developed on the two monocots studied (leek and sweetcorn). Plant species were also differentiated on the basis of expanding lesions (cultivated and wild carrot, dill and fennel) or non-expanding lesions (other dicot species). Typical A. dauci conidia were observed after in vitro incubation of leaves with symptoms. Fungal structures were isolated from lesions and A. dauci was confirmed on the basis of conidial morphology and specific conventional PCR results. Genotyping of individual isolates performed with microsatellite markers confirmed the presence of the inoculated isolate. The results clearly showed that, in controlled conditions, the host range of A. dauci is not restricted to carrot.

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