title: Secretome of the free-living mycelium from the ectomycorrhizal basidiomycete Laccaria bicolor.
abstract: The ectomycorrhizal basidiomycete Laccaria bicolor has a dual lifestyle with a transitory soil saprotrophic phase and a longer mutualistic interaction with tree roots. Recent evidence suggests that secreted proteins play key roles in host plant colonisation and symbiosis development. However, a limited number of secreted proteins have been characterized, and the full spectrum of effectors involved in the mycobiont invasion and survival remains unknown. We analyzed the extracellular proteins secreted in growth medium by free-living mycelium of L. bicolor as a proxy for its saprotrophic phase. The proteomic analyses (two-dimensional electrophoresis and shotgun proteomics) were substantiated by whole-genome expression transcript profiling on ectomycorrhizal roots. Among the 224 proteins identified were carbohydrate-acting enzymes likely involved in the cell wall remodelling linked to hyphal growth as well as secreted proteases possibly digesting soil organic compounds and/or fending off competitors, pathogens, and predators. Evidence of gene expression was found in ectomycorrhizal roots for 210 of them. These findings provide the first global view of the secretome of a mutualistic symbiont and shed some light on the mechanisms controlling cell wall remodelling during the hyphal growth. They also revealed many novel putative secreted proteins of unknown function, including one mycorrhiza-induced small secreted protein.
authors.affiliation: INRA, UMR1202 BIOGECO, Cestas, France. comtasr@yahoo.fr
authors.forename: Delphine
authors.initials: D
authors.lastname: Vincent
authors.forename: Annegret
authors.initials: A
authors.lastname: Kohler
authors.forename: Stephane
authors.initials: S
authors.lastname: Claverol
authors.forename: Emilie
authors.initials: E
authors.lastname: Solier
authors.forename: Johann
authors.initials: J
authors.lastname: Joets
authors.forename: Julien
authors.initials: J
authors.lastname: Gibon
authors.forename: Marc-Henri
authors.initials: MH
authors.lastname: Lebrun
authors.forename: Christophe
authors.initials: C
authors.lastname: Plomion
authors.forename: Francis
authors.initials: F
authors.lastname: Martin
mesh_terms: D015180:Electrophoresis, Gel, Two-Dimensional; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal; D055399:Laccaria / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D025282:Mycelium / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D038821:Mycorrhizae / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D010446:Peptide Fragments / Q000737:chemistry; D059748:Proteolysis; D020543:Proteome / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D053719:Tandem Mass Spectrometry
chemical_list: D005656:Fungal Proteins; D010446:Peptide Fragments; D020543:Proteome