Secretome of the Free-living Mycelium from the Ectomycorrhizal Basidiomycete Laccaria bicolor
Delphine Vincent, Annegret Kohler, Stephane Claverol, Emilie Solier, Johann Joets, Julien Gibon, Marc-Henri Lebrun, Christophe Plomion, and Francis Martin
2012 January 06, Journal of Proteome Research 11(1), 157-171
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.
Gene Ontology (GO) classification of L. bicolor identified secreted proteins using 2-DE (2-D), 1-D shotgun (1-D), IPG shotgun (IPG) or all three techniques (all), according to (A) biological process (BP), (B) molecular function (MF), and (C) cellular component (CC).
Venn diagram displaying the number of L. bicolor secreted proteins identified by each resolving method and combined to Gene Ontology (GO) Functional Classification according to biological process (BP), molecular function (MF), and cellular component (CC).
Secretome of the Free-living Mycelium from the Ectomycorrhizal Basidiomycete Laccaria bicolor Delphine Vincent, Annegret Kohler, Stephane Claverol, Emilie Solier, Johann Joets, Julien Gibon, Marc-Henri Lebrun, Christophe Plomion, and Francis Martin Journal of Proteome Research 2012 11 (1), 157-171