title: Development of the Poplar-Laccaria bicolor Ectomycorrhiza Modifies Root Auxin Metabolism, Signaling, and Response.
abstract: Root systems of host trees are known to establish ectomycorrhizae (ECM) interactions with rhizospheric fungi. This mutualistic association leads to dramatic developmental modifications in root architecture, with the formation of numerous short and swollen lateral roots ensheathed by a fungal mantle. Knowing that auxin plays a crucial role in root development, we investigated how auxin metabolism, signaling, and response are affected in poplar (Populus spp.)-Laccaria bicolor ECM roots. The plant-fungus interaction leads to the arrest of lateral root growth with simultaneous attenuation of the synthetic auxin response element DR5. Measurement of auxin-related metabolites in the free-living partners revealed that the mycelium of L. bicolor produces high concentrations of the auxin indole-3-acetic acid (IAA). Metabolic profiling showed an accumulation of IAA and changes in the indol-3-pyruvic acid-dependent IAA biosynthesis and IAA conjugation and degradation pathways during ECM formation. The global analysis of auxin response gene expression and the regulation of AUXIN SIGNALING F-BOX PROTEIN5, AUXIN/IAA, and AUXIN RESPONSE FACTOR expression in ECM roots suggested that symbiosis-dependent auxin signaling is activated during the colonization by L. bicolor. Taking all this evidence into account, we propose a model in which auxin signaling plays a crucial role in the modification of root growth during ECM formation.
authors.affiliation: Institut National de la Recherche Agronomique and Université de Lorraine, Unité Mixte de Recherche Interactions Arbres/Microorganismes 1136, Institut National de la Recherche Agronomique-Nancy, F-54280 Champenoux, France (A.V., J.F., A.K., F.M., V.L.); andUmeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 901 83 Umea, Sweden (A.P., K.L.).
authors.forename: Alice
authors.initials: A
authors.lastname: Vayssières
authors.affiliation: Institut National de la Recherche Agronomique and Université de Lorraine, Unité Mixte de Recherche Interactions Arbres/Microorganismes 1136, Institut National de la Recherche Agronomique-Nancy, F-54280 Champenoux, France (A.V., J.F., A.K., F.M., V.L.); andUmeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 901 83 Umea, Sweden (A.P., K.L.).
authors.forename: Ales
authors.initials: A
authors.lastname: Pěnčík
authors.affiliation: Institut National de la Recherche Agronomique and Université de Lorraine, Unité Mixte de Recherche Interactions Arbres/Microorganismes 1136, Institut National de la Recherche Agronomique-Nancy, F-54280 Champenoux, France (A.V., J.F., A.K., F.M., V.L.); andUmeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 901 83 Umea, Sweden (A.P., K.L.).
authors.forename: Judith
authors.identifier: http://orcid.org/0000-0002-0444-822X
authors.initials: J
authors.lastname: Felten
authors.affiliation: Institut National de la Recherche Agronomique and Université de Lorraine, Unité Mixte de Recherche Interactions Arbres/Microorganismes 1136, Institut National de la Recherche Agronomique-Nancy, F-54280 Champenoux, France (A.V., J.F., A.K., F.M., V.L.); andUmeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 901 83 Umea, Sweden (A.P., K.L.).
authors.forename: Annegret
authors.initials: A
authors.lastname: Kohler
authors.affiliation: Institut National de la Recherche Agronomique and Université de Lorraine, Unité Mixte de Recherche Interactions Arbres/Microorganismes 1136, Institut National de la Recherche Agronomique-Nancy, F-54280 Champenoux, France (A.V., J.F., A.K., F.M., V.L.); andUmeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 901 83 Umea, Sweden (A.P., K.L.).
authors.forename: Karin
authors.identifier: http://orcid.org/0000-0003-2901-189X
authors.initials: K
authors.lastname: Ljung
authors.affiliation: Institut National de la Recherche Agronomique and Université de Lorraine, Unité Mixte de Recherche Interactions Arbres/Microorganismes 1136, Institut National de la Recherche Agronomique-Nancy, F-54280 Champenoux, France (A.V., J.F., A.K., F.M., V.L.); andUmeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 901 83 Umea, Sweden (A.P., K.L.).
authors.forename: Francis
authors.identifier: http://orcid.org/0000-0002-4737-3715
authors.initials: F
authors.lastname: Martin
authors.affiliation: Institut National de la Recherche Agronomique and Université de Lorraine, Unité Mixte de Recherche Interactions Arbres/Microorganismes 1136, Institut National de la Recherche Agronomique-Nancy, F-54280 Champenoux, France (A.V., J.F., A.K., F.M., V.L.); andUmeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 901 83 Umea, Sweden (A.P., K.L.) valerie.legue@univ-bpclermont.fr.
authors.forename: Valérie
authors.initials: V
authors.lastname: Legué
mesh_terms: D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D007210:Indoleacetic Acids / Q000378:metabolism* / Q000494:pharmacology; D055399:Laccaria / Q000187:drug effects / Q000502:physiology*; D055442:Metabolome / Q000187:drug effects; D008954:Models, Biological; D015999:Multivariate Analysis; D038821:Mycorrhizae / Q000187:drug effects / Q000502:physiology*; D010940:Plant Proteins / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism* / Q000382:microbiology*; D032107:Populus / Q000187:drug effects / Q000382:microbiology*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D007210:Indoleacetic Acids; D010940:Plant Proteins; C030737:indoleacetic acid