title: A Core Gene Set Describes the Molecular Basis of Mutualism and Antagonism in Epichloë spp.
abstract: Beneficial plant-fungal interactions play an important role in the ability of plants to survive changing environmental conditions. In contrast, phytopathogenic fungi fall at the opposite end of the symbiotic spectrum, causing reduced host growth or even death. In order to exploit beneficial interactions and prevent pathogenic ones, it is essential to understand the molecular differences underlying these alternative states. The association between the endophyte Epichloë festucae and Lolium perenne (perennial ryegrass) is an excellent system for studying these molecular patterns due to the existence of several fungal mutants that have an antagonistic rather than a mutualistic interaction with the host plant. By comparing gene expression in a wild-type beneficial association with three mutant antagonistic associations disrupted in key signaling genes, we identified a core set of 182 genes that show common differential expression patterns between these two states. These gene expression changes are indicative of a nutrient-starvation response, as supported by the upregulation of genes encoding degradative enzymes, transporters, and primary metabolism, and downregulation of genes encoding putative small-secreted proteins and secondary metabolism. These results suggest that disruption of a mutualistic symbiotic interaction may lead to an elevated uptake and degradation of host-derived nutrients and cell-wall components, reminiscent of phytopathogenic interactions.
authors.forename: Carla J
authors.initials: CJ
authors.lastname: Eaton
authors.forename: Pierre-Yves
authors.initials: PY
authors.lastname: Dupont
authors.forename: Peter
authors.initials: P
authors.lastname: Solomon
authors.forename: William
authors.initials: W
authors.lastname: Clayton
authors.forename: Barry
authors.initials: B
authors.lastname: Scott
authors.forename: Murray P
authors.initials: MP
authors.lastname: Cox
mesh_terms: D002473:Cell Wall / Q000378:metabolism; D015536:Down-Regulation; D060026:Endophytes; D055329:Epichloe / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D004876:Ergot Alkaloids / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics*; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D059014:High-Throughput Nucleotide Sequencing; D054884:Host-Pathogen Interactions; D025301:Hyphae; D026121:Indole Alkaloids / Q000737:chemistry / Q000378:metabolism; D008129:Lolium / Q000382:microbiology*; D005810:Multigene Family; D009183:Mycotoxins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018515:Plant Leaves / Q000382:microbiology; D018520:Plant Shoots / Q000382:microbiology; D017423:Sequence Analysis, RNA; D015398:Signal Transduction; D013559:Symbiosis; D015854:Up-Regulation
chemical_list: D004876:Ergot Alkaloids; D005656:Fungal Proteins; D026121:Indole Alkaloids; D009183:Mycotoxins; C033673:lolitrem B