Cellular and molecular defence-related root responses to invasion by arbuscular mycorrhizal fungi

Authors

  • VIVIENNE GIANINAZZI-PEARSON,

    1. Laboratoire de Phytoparasitologie INRA/CNRS, SGAP, Institut National de‘la Recherche Agronomique, BV 1540, 21034 Dijon Cédex, France
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  • ELIANE DUMAS-GAUDOT,

    1. Laboratoire de Phytoparasitologie INRA/CNRS, SGAP, Institut National de‘la Recherche Agronomique, BV 1540, 21034 Dijon Cédex, France
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  • ARMELLE GOLLOTTE,

    Corresponding author
    1. Laboratoire de Phytoparasitologie INRA/CNRS, SGAP, Institut National de‘la Recherche Agronomique, BV 1540, 21034 Dijon Cédex, France
      1Department of Land Resources, Scottish Agricultural College, Doig Scott Building, Craibstone Estate, Aberdeen AB2 9TQ, UK
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  • A. TAHIRI- ALAOUI,

    Corresponding author
    1. Laboratoire de Phytoparasitologie INRA/CNRS, SGAP, Institut National de‘la Recherche Agronomique, BV 1540, 21034 Dijon Cédex, France
      2Rothamsted Experimental Station, Plant Pathology Department, Harpenden, Herts AL5 2JQ, UK.
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  • S. GIANINAZZI

    1. Laboratoire de Phytoparasitologie INRA/CNRS, SGAP, Institut National de‘la Recherche Agronomique, BV 1540, 21034 Dijon Cédex, France
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  • 1

    Department of Land Resources, Scottish Agricultural College, Doig Scott Building, Craibstone Estate, Aberdeen AB2 9TQ, UK

  • 2

    Rothamsted Experimental Station, Plant Pathology Department, Harpenden, Herts AL5 2JQ, UK.

SUMMARY

Arbuscular mycorrhizal (AM) fungi, which date from the Devonian era, must have dealt very early on with problems of plant defence, a tactic which has enabled them to colonize roots of most extant plant taxa. Conversely, plants forming arbuscular mycorrhiza must exert some sort of control over the fungi during symbiotic interactions since mycelial proliferation within roots is confined to the cortical parenchyma tissue. Plants possess a panoply of defence mechanisms which are triggered by microbial attack. Here we review present-day knowledge of defence-related root responses to colonization by AM fungi, and assess their possible implications in the symbiosis. Weak, transient, unco-ordinated or extremely localized activation of inducible defence responses occurs during compatible interactions in AM which differs from that in plant–pathogen interactions. When symbiosis-related plant genes are mutated, typical defence responses are associated with resulting root resistance to arbuscular mycorrhizal fungi whilst, contrastingly, plants constitutively expressing defence genes are unaffected in their symbiotic capacities. The mechanisms by which plants can modulate defence responses during symbiotic interactions and the way in which A1V1 fungi might contend with these are discussed.

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