title: A specialized ABC efflux transporter GcABC-G1 confers monoterpene resistance to Grosmannia clavigera, a bark beetle-associated fungal pathogen of pine trees.
abstract: Grosmannia clavigera is a bark beetle-vectored pine pathogen in the mountain pine beetle epidemic in western North America. Grosmannia clavigera colonizes pines despite the trees' massive oleoresin terpenoid defences. We are using a functional genomics approach to identify G. clavigera's mechanisms of adaptation to pine defences. We annotated the ABC transporters in the G. clavigera genome and generated RNA-seq transcriptomes from G. clavigera grown with a range of terpenes. We functionally characterized GcABC-G1, a pleiotropic drug resistance (PDR) transporter that was highly induced by terpenes, using qRT-PCR, gene knock-out and heterologous expression in yeast. Deleting GcABC-G1 increased G. clavigera's sensitivity to monoterpenes and delayed development of symptoms in inoculated young lodgepole pine trees. Heterologous expression of GcABC-G1 in yeast increased tolerance to monoterpenes. G. clavigera but not the deletion mutant, can use (+)-limonene as a carbon source. Phylogenetic analysis placed GcABC-G1 outside the ascomycete PDR transporter clades. G. clavigera appears to have evolved two mechanisms to survive and grow when exposed to monoterpenes: GcABC-G1 controls monoterpene levels within the fungal cells and G. clavigera uses monoterpenes as a carbon source. This work has implications for understanding adaptation to host defences in an important forest insect-fungal system, and potentially for metabolic engineering of terpenoid production in yeast.
authors.affiliation: Department of Wood Sciences, University of British Columbia, Vancouver, BC, Canada, V6T1Z4.
authors.forename: Ye
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Wood Sciences, University of British Columbia, Vancouver, BC, Canada, V6T1Z4.
authors.forename: Lynette
authors.initials: L
authors.lastname: Lim
authors.affiliation: Department of Wood Sciences, University of British Columbia, Vancouver, BC, Canada, V6T1Z4.
authors.forename: Scott
authors.initials: S
authors.lastname: DiGuistini
authors.affiliation: BC Cancer Agency Genome Sciences Centre, Vancouver, BC, Canada, V5Z 4E6.
authors.forename: Gordon
authors.initials: G
authors.lastname: Robertson
authors.affiliation: Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada, V6T1Z4.
authors.forename: Jörg
authors.initials: J
authors.lastname: Bohlmann
authors.affiliation: Department of Wood Sciences, University of British Columbia, Vancouver, BC, Canada, V6T1Z4.
authors.forename: Colette
authors.initials: C
authors.lastname: Breuil
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D001203:Ascomycota / Q000187:drug effects* / Q000235:genetics; D025141:Drug Resistance, Fungal / Q000235:genetics*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D055786:Gene Knockout Techniques; D023281:Genomics; D016013:Likelihood Functions; D010802:Phylogeny; D028223:Pinus / Q000235:genetics / Q000382:microbiology*; D010935:Plant Diseases / Q000382:microbiology*; D013729:Terpenes / Q000494:pharmacology*; D059467:Transcriptome
chemical_list: D018528:ATP-Binding Cassette Transporters; D005656:Fungal Proteins; D013729:Terpenes