title: SymB and SymC, two membrane associated proteins, are required for Epichloë festucae hyphal cell-cell fusion and maintenance of a mutualistic interaction with Lolium perenne.
abstract: Cell-cell fusion in fungi is required for colony formation, nutrient transfer and signal transduction. Disruption of genes required for hyphal fusion in Epichloë festucae, a mutualistic symbiont of Lolium grasses, severely disrupts the host interaction phenotype. They examined whether symB and symC, the E. festucae homologs of Podospora anserina self-signaling genes IDC2 and IDC3, are required for E. festucae hyphal fusion and host symbiosis. Deletion mutants of these genes were defective in hyphal cell fusion, formed intra-hyphal hyphae, and had enhanced conidiation. SymB-GFP and SymC-mRFP1 localize to plasma membrane, septa and points of hyphal cell fusion. Plants infected with ΔsymB and ΔsymC strains were severely stunted. Hyphae of the mutants colonized vascular bundles, were more abundant than wild type in the intercellular spaces and formed intra-hyphal hyphae. Although these phenotypes are identical to those previously observed for cell wall integrity MAP kinase mutants no difference was observed in the basal level of MpkA phosphorylation or its cellular localization in the mutant backgrounds. Both genes contain binding sites for the transcription factor ProA. Collectively these results show that SymB and SymC are key components of a conserved signaling network for E. festucae to maintain a mutualistic symbiotic interaction within L. perenne.
authors.affiliation: Institute of Fundamental Sciences, Massey University, Palmerston North, 4442, New Zealand.|Bioprotection Research Centre, Massey University, Palmerston North, 4442, New Zealand.
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Green
authors.affiliation: Institute of Fundamental Sciences, Massey University, Palmerston North, 4442, New Zealand.|Leibniz Institute of Vegetable and Ornamental Crops, Großbeeren, 14979, Germany.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Becker
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601, Japan.
authors.forename: Aiko
authors.initials: A
authors.lastname: Tanaka
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601, Japan.
authors.forename: Daigo
authors.initials: D
authors.lastname: Takemoto
authors.affiliation: Institute of Fundamental Sciences, Massey University, Palmerston North, 4442, New Zealand.
authors.forename: Helen L
authors.initials: HL
authors.lastname: Fitzsimons
authors.affiliation: Freiburg Institute for Advanced Studies, Albert-Ludwigs Universität Freiburg, Freiburg, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Seiler
authors.affiliation: Université Paris Diderot, Sorbonne Paris Cité, Laboratoire des Energies de Demain, Paris, 75205, France.
authors.forename: Hervé
authors.initials: H
authors.lastname: Lalucque
authors.affiliation: Université Paris Diderot, Sorbonne Paris Cité, Laboratoire des Energies de Demain, Paris, 75205, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Silar
authors.affiliation: Institute of Fundamental Sciences, Massey University, Palmerston North, 4442, New Zealand.|Bioprotection Research Centre, Massey University, Palmerston North, 4442, New Zealand.
authors.forename: Barry
authors.initials: B
authors.lastname: Scott
mesh_terms: D002459:Cell Fusion; D055329:Epichloe / Q000235:genetics* / Q000502:physiology; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D025301:Hyphae / Q000235:genetics* / Q000502:physiology; D008129:Lolium / Q000254:growth & development* / Q000382:microbiology; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000235:genetics; D017384:Sequence Deletion / Q000235:genetics; D013172:Spores, Fungal / Q000235:genetics / Q000254:growth & development*; D013559:Symbiosis / Q000235:genetics*; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D008565:Membrane Proteins; D014157:Transcription Factors; D020928:Mitogen-Activated Protein Kinases