title: Differential Expression of Genes Involved in Host Recognition, Attachment, and Degradation in the Mycoparasite Tolypocladium ophioglossoides.
abstract: The ability of a fungus to infect novel hosts is dependent on changes in gene content, expression, or regulation. Examining gene expression under simulated host conditions can explore which genes may contribute to host jumping. Insect pathogenesis is the inferred ancestral character state for species of Tolypocladium, however several species are parasites of truffles, including Tolypocladium ophioglossoides. To identify potentially crucial genes in this interkingdom host switch, T. ophioglossoides was grown on four media conditions: media containing the inner and outer portions of its natural host (truffles of Elaphomyces), cuticles from an ancestral host (beetle), and a rich medium (Yeast Malt). Through high-throughput RNASeq of mRNA from these conditions, many differentially expressed genes were identified in the experiment. These included PTH11-related G-protein-coupled receptors (GPCRs) hypothesized to be involved in host recognition, and also found to be upregulated in insect pathogens. A divergent chitinase with a signal peptide was also found to be highly upregulated on media containing truffle tissue, suggesting an exogenous degradative activity in the presence of the truffle host. The adhesin gene, Mad1, was highly expressed on truffle media as well. A BiNGO analysis of overrepresented GO terms from genes expressed during each growth condition found that genes involved in redox reactions and transmembrane transport were the most overrepresented during T. ophioglossoides growth on truffle media, suggesting their importance in growth on fungal tissue as compared to other hosts and environments. Genes involved in secondary metabolism were most highly expressed during growth on insect tissue, suggesting that their products may not be necessary during parasitism of Elaphomyces. This study provides clues into understanding genetic mechanisms underlying the transition from insect to truffle parasitism.
authors.affiliation: Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, 97331 alishaq@umich.edu.
authors.forename: C Alisha
authors.identifier: http://orcid.org/0000-0003-0260-8995
authors.initials: CA
authors.lastname: Quandt
authors.affiliation: Department of Statistics, Oregon State University, Corvallis, Oregon, 97331.
authors.forename: Yanming
authors.initials: Y
authors.lastname: Di
authors.affiliation: Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, 97331.
authors.forename: Justin
authors.initials: J
authors.lastname: Elser
authors.affiliation: Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, 97331.
authors.forename: Pankaj
authors.initials: P
authors.lastname: Jaiswal
authors.affiliation: Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, 97331.
authors.forename: Joseph W
authors.initials: JW
authors.lastname: Spatafora
mesh_terms: D001203:Ascomycota / Q000145:classification / Q000502:physiology*; D002688:Chitinases / Q000235:genetics / Q000378:metabolism; D016000:Cluster Analysis; D019295:Computational Biology / Q000379:methods; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal; D063990:Gene Ontology; D005800:Genes, Fungal; D010802:Phylogeny; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism; D064210:Secondary Metabolism / Q000235:genetics
chemical_list: D043562:Receptors, G-Protein-Coupled; D002688:Chitinases
keywords: Elaphomyces; PTH11 GPCR; RNA-Seq; adhesin; chitinase