How does a symbiotic fungus modulate expression of its host-plant nitrite reductase?
* 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.
Bailly
Julie
J
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.
Debaud
Jean-Claude
JC
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.
Verner
Marie-Christine
MC
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.
Plassard
Claude
C
INRA, UMR 1222, Rhizosphère & Symbiose, 2 Place Viala, F-34060 Montpellier Cedex 01, France.
Chalot
Michel
M
Nancy-University, Research Unit 1136 INRA/UHP 'Tree-microbe Interactions', BP 239, F-54506 Vandoeuvre-les-Nancy Cedex, France.
Marmeisse
Roland
R
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.
Fraissinet-Tachet
Laurence
L
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.
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
D010940:Plant Proteins; D012331:RNA, Fungal; D018749:RNA, Plant; D012987:Soil; D050901:Nitrate Reductase; D009584:Nitrogen