title: How does a symbiotic fungus modulate expression of its host-plant nitrite reductase?
abstract: * In the mycorrhizal association, changes in the metabolic activities expressed by the plant and fungal partners could result from modulations in the quantity and nature of nutrients available at the plant-fungus interface. This hypothesis was tested for the nitrite reductase gene in the association Hebeloma cylindrosporumxPinus pinaster. * Transcripts from plant and fungal nitrite reductases and a fungal ammonium transporter were quantified in control uninoculated roots, extraradical mycelia and mycorrhizas formed by either wild-type or nitrate reductase deficient fungal strains. * The fungal genes were downregulated in mycorrhizas compared with extraradical hyphae. The plant nitrite reductase was induced only transiently by NO(3)(-) in the association with a wild-type strain, but permanently expressed at a high level in mycorrhizas formed by the deficient mutant. * These results suggest that reduced nitrogen compounds transferred from the fungus to the root cortical cells repress the plant nitrite reductase, thus highlighting a plant gene regulation by the nutrients available in the Hartig net.
authors.affiliation: Université de Lyon, Lyon, F-69003, France; Université Lyon1, Lyon, F-69003, France; IFR 41, Lyon, Villeurbanne, F-69622, France; Laboratoire CNRS, UMR5557, USC INRA 1193, Ecologie Microbienne, Bâtiment A. Lwoff, 43 Boulevard du 11 novembre 1918, F-69622 Villeurbanne Cedex, France.
authors.forename: Julie
authors.initials: J
authors.lastname: Bailly
authors.affiliation: Université de Lyon, Lyon, F-69003, France; Université Lyon1, Lyon, F-69003, France; IFR 41, Lyon, Villeurbanne, F-69622, France; Laboratoire CNRS, UMR5557, USC INRA 1193, Ecologie Microbienne, Bâtiment A. Lwoff, 43 Boulevard du 11 novembre 1918, F-69622 Villeurbanne Cedex, France.
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Debaud
authors.affiliation: Université de Lyon, Lyon, F-69003, France; Université Lyon1, Lyon, F-69003, France; IFR 41, Lyon, Villeurbanne, F-69622, France; Laboratoire CNRS, UMR5557, USC INRA 1193, Ecologie Microbienne, Bâtiment A. Lwoff, 43 Boulevard du 11 novembre 1918, F-69622 Villeurbanne Cedex, France.
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Verner
authors.affiliation: INRA, UMR 1222, Rhizosphère & Symbiose, 2 Place Viala, F-34060 Montpellier Cedex 01, France.
authors.forename: Claude
authors.initials: C
authors.lastname: Plassard
authors.affiliation: Nancy-University, Research Unit 1136 INRA/UHP 'Tree-microbe Interactions', BP 239, F-54506 Vandoeuvre-les-Nancy Cedex, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Chalot
authors.affiliation: Université de Lyon, Lyon, F-69003, France; Université Lyon1, Lyon, F-69003, France; IFR 41, Lyon, Villeurbanne, F-69622, France; Laboratoire CNRS, UMR5557, USC INRA 1193, Ecologie Microbienne, Bâtiment A. Lwoff, 43 Boulevard du 11 novembre 1918, F-69622 Villeurbanne Cedex, France.
authors.forename: Roland
authors.initials: R
authors.lastname: Marmeisse
authors.affiliation: Université de Lyon, Lyon, F-69003, France; Université Lyon1, Lyon, F-69003, France; IFR 41, Lyon, Villeurbanne, F-69622, France; Laboratoire CNRS, UMR5557, USC INRA 1193, Ecologie Microbienne, Bâtiment A. Lwoff, 43 Boulevard du 11 novembre 1918, F-69622 Villeurbanne Cedex, France.
authors.forename: Laurence
authors.initials: L
authors.lastname: Fraissinet-Tachet
mesh_terms: D008401:Gas Chromatography-Mass Spectrometry; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D038821:Mycorrhizae / Q000235:genetics / Q000502:physiology*; D050901:Nitrate Reductase / Q000235:genetics; D009584:Nitrogen / Q000378:metabolism; D028223:Pinus / Q000201:enzymology / Q000235:genetics / Q000382:microbiology*; D010940:Plant Proteins / Q000235:genetics; D012331:RNA, Fungal / Q000235:genetics / Q000302:isolation & purification; D018749:RNA, Plant / Q000235:genetics / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012987:Soil / Q000032:analysis; D013559:Symbiosis
chemical_list: D010940:Plant Proteins; D012331:RNA, Fungal; D018749:RNA, Plant; D012987:Soil; D050901:Nitrate Reductase; D009584:Nitrogen