Ethylene and jasmonic acid act as negative modulators during mutualistic symbiosis between Laccaria bicolor and Populus roots

Authors

  • Jonathan M. Plett,

    Corresponding author
    1. INRA, UMR 1136 INRA-University Henri Poincaré, Lab of Excellence ARBRE, Interactions Arbres/Microorganismes, INRA-Nancy, Champenoux, France
    2. Hawkesbury Institute for the Environment, University of Western Sydney, Richmond, NSW, Australia
    • Author for correspondence:

      Jonathan Plett

      Tel: +61 4578 1097

      Email: j.plett@uws.edu.au

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  • Amit Khachane,

    1. Hawkesbury Institute for the Environment, University of Western Sydney, Richmond, NSW, Australia
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  • Malika Ouassou,

    1. INRA, UMR 1136 INRA-University Henri Poincaré, Lab of Excellence ARBRE, Interactions Arbres/Microorganismes, INRA-Nancy, Champenoux, France
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  • Björn Sundberg,

    1. Umea Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umea, Sweden
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  • Annegret Kohler,

    1. INRA, UMR 1136 INRA-University Henri Poincaré, Lab of Excellence ARBRE, Interactions Arbres/Microorganismes, INRA-Nancy, Champenoux, France
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  • Francis Martin

    1. INRA, UMR 1136 INRA-University Henri Poincaré, Lab of Excellence ARBRE, Interactions Arbres/Microorganismes, INRA-Nancy, Champenoux, France
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Summary

  • The plant hormones ethylene, jasmonic acid and salicylic acid have interconnecting roles during the response of plant tissues to mutualistic and pathogenic symbionts.
  • We used morphological studies of transgenic- or hormone-treated Populus roots as well as whole-genome oligoarrays to examine how these hormones affect root colonization by the mutualistic ectomycorrhizal fungus Laccaria bicolor S238N.
  • We found that genes regulated by ethylene, jasmonic acid and salicylic acid were regulated in the late stages of the interaction between L. bicolor and poplar. Both ethylene and jasmonic acid treatments were found to impede fungal colonization of roots, and this effect was correlated to an increase in the expression of certain transcription factors (e.g. ETHYLENE RESPONSE FACTOR1) and a decrease in the expression of genes associated with microbial perception and cell wall modification. Further, we found that ethylene and jasmonic acid showed extensive transcriptional cross-talk, cross-talk that was opposed by salicylic acid signaling.
  • We conclude that ethylene and jasmonic acid pathways are induced late in the colonization of root tissues in order to limit fungal growth within roots. This induction is probably an adaptive response by the plant such that its growth and vigor are not compromised by the fungus.

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