Detection and identification of bacteria intimately associated with fungi of the order Sebacinales

Authors

  • Monica Sharma,

    1. Institute of Phytopathology and Applied Zoology, Research Centre for BioSystems, Land use and Nutrition, Justus-Liebig-University Giessen, D-35392 Giessen, Germany.
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  • Michael Schmid,

    1. Department Microbe–Plant Interactions, Helmholtz Zentrum München, German Research Center for Environmental Health, D-85764 Neuherberg, Germany.
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  • Michael Rothballer,

    1. Department Microbe–Plant Interactions, Helmholtz Zentrum München, German Research Center for Environmental Health, D-85764 Neuherberg, Germany.
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  • Gerd Hause,

    1. Martin-Luther-University Halle-Wittenberg, Biocenter, D-06120, Halle/Saale, Germany.
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  • Alga Zuccaro,

    1. Institute of Phytopathology and Applied Zoology, Research Centre for BioSystems, Land use and Nutrition, Justus-Liebig-University Giessen, D-35392 Giessen, Germany.
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  • Jafargholi Imani,

    1. Institute of Phytopathology and Applied Zoology, Research Centre for BioSystems, Land use and Nutrition, Justus-Liebig-University Giessen, D-35392 Giessen, Germany.
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  • Peter Kämpfer,

    1. Institute of Applied Microbiology, Research Centre for BioSystems, Land use and Nutrition, Justus-Liebig-University Giessen, D-35392 Giessen, Germany.
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  • Eugen Domann,

    1. Institute of Medical Microbiology, UKGM, D-35392 Giessen, Germany.
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  • Patrick Schäfer,

    1. Institute of Phytopathology and Applied Zoology, Research Centre for BioSystems, Land use and Nutrition, Justus-Liebig-University Giessen, D-35392 Giessen, Germany.
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  • Anton Hartmann,

    1. Department Microbe–Plant Interactions, Helmholtz Zentrum München, German Research Center for Environmental Health, D-85764 Neuherberg, Germany.
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  • Karl-Heinz Kogel

    Corresponding author
    1. Institute of Phytopathology and Applied Zoology, Research Centre for BioSystems, Land use and Nutrition, Justus-Liebig-University Giessen, D-35392 Giessen, Germany.
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*E-mail Karl-Heinz.Kogel@agrar.uni-giessen.de; Tel. (+49) 641 99 37490; Fax (+49) 641 99 37499.

Summary

Because of their beneficial impact on plants, the highly diverse mycorrhizal fungi grouped in the order Sebacinales lay claim to high ecological and agricultural significance. Here, we describe for the first time associations of Sebacinoid members with bacteria. Using quantitative PCR, denaturating gradient gel electrophoresis and fluorescence in situ hybridization, we detected an intimate association between Piriformospora indica and Rhizobium radiobacter, an α-Proteobacterium. The stability of the association, vertical transmission of the bacteria during asexual fungal reproduction and fungal plant colonization was monitored using R. radiobacter-specific primers. Treatment of mycelium or fungal protoplasts with antibiotics highly efficient against the free bacteria failed to cure the fungus. Barley seedlings dip-inoculated with R. radiobacter showed growth promotion and systemic resistance to the powdery mildew fungus Blumeria graminis comparable to P. indica inoculation. By screening additional isolates of the Sebacina vermifera complex, three species-specific associations with bacteria from the genera Paenibacillus, Acinetobacter and Rhodococcus were found. These findings suggest that Sebacinales species regularly undergo complex interactions involving host plants and bacteria reminiscent of other ectomycorrhizal and endomycorrhizal associations.

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