title: Functional genomics-guided discovery of a light-activated phytotoxin in the wheat pathogen Parastagonospora nodorum via pathway activation.
abstract: Parastagonospora nodorum is an important pathogen of wheat. The contribution of secondary metabolites to this pathosystem is poorly understood. A biosynthetic gene cluster (SNOG_08608-08616) has been shown to be upregulated during the late stage of P. nodorum wheat leaf infection. The gene cluster shares several homologues with the Cercospora nicotianae CTB gene cluster encoding the biosynthesis of cercosporin. Activation of the gene cluster by overexpression (OE) of the transcription factor gene (SNOG_08609) in P. nodorum resulted in the production of elsinochrome C, a perelyenequinone phytotoxin structurally similar to cercosporin. Heterologous expression of the polyketide synthase gene elcA from the gene cluster in Aspergillus nidulans resulted in the production of the polyketide precursor nortoralactone common to the cercosporin pathway. Elsinochrome C could be detected on wheat leaves infected with P. nodorum, but not in the elcA disruption mutant. The compound was shown to exhibit necrotic activity on wheat leaves in a light-dependent manner. Wheat seedling infection assays showed that ΔelcA exhibited reduced virulence compared with wild type, while infection by an OE strain overproducing elsinochrome C resulted in larger lesions on leaves. These data provided evidence that elsinochrome C contributes to the virulence of P. nodorum against wheat.
authors.affiliation: School of Molecular Sciences, University of Western Australia, Perth, WA, 6009, Australia.|Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia.
authors.forename: Yit-Heng
authors.identifier: 0000-0001-7719-7524
authors.initials: YH
authors.lastname: Chooi
authors.affiliation: Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia.
authors.forename: Guozhi
authors.initials: G
authors.lastname: Zhang
authors.affiliation: School of Molecular Sciences, University of Western Australia, Perth, WA, 6009, Australia.
authors.forename: Jinyu
authors.initials: J
authors.lastname: Hu
authors.affiliation: Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia.
authors.forename: Mariano Jordi
authors.initials: MJ
authors.lastname: Muria-Gonzalez
authors.affiliation: Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia.
authors.forename: Phuong N
authors.initials: PN
authors.lastname: Tran
authors.affiliation: School of Molecular Sciences, University of Western Australia, Perth, WA, 6009, Australia.
authors.forename: Amber
authors.initials: A
authors.lastname: Pettitt
authors.affiliation: Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia.
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Maier
authors.affiliation: Research School of Chemistry, Australian National University, Canberra, ACT, 2601, Australia.
authors.forename: Russell A
authors.initials: RA
authors.lastname: Barrow
authors.affiliation: Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia.
authors.forename: Peter S
authors.initials: PS
authors.lastname: Solomon
mesh_terms: D001203:Ascomycota / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity; D001233:Aspergillus nidulans / Q000235:genetics / Q000378:metabolism; D004789:Enzyme Activation / Q000235:genetics; D023281:Genomics; D005810:Multigene Family / Q000235:genetics*; D010569:Perylene / Q000031:analogs & derivatives* / Q000378:metabolism; D010935:Plant Diseases / Q000382:microbiology; D018515:Plant Leaves / Q000378:metabolism / Q000382:microbiology; D048630:Polyketide Synthases / Q000096:biosynthesis / Q000235:genetics; D011809:Quinones / Q000378:metabolism*; D036226:Seedlings / Q000382:microbiology; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics; D014908:Triticum / Q000382:microbiology*; D014774:Virulence / Q000235:genetics
chemical_list: D011809:Quinones; D014157:Transcription Factors; C062775:elsinochrome A; D010569:Perylene; D048630:Polyketide Synthases; C026363:cercosporin