title: SnTox1, a Parastagonospora nodorum necrotrophic effector, is a dual-function protein that facilitates infection while protecting from wheat-produced chitinases.
abstract: SnTox1 induces programmed cell death and the up-regulation of pathogenesis-related genes including chitinases. Additionally, SnTox1 has structural homology to several plant chitin-binding proteins. Therefore, we evaluated SnTox1 for chitin binding and localization. We transformed an avirulent strain of Parastagonospora nodorum as well as three nonpathogens of wheat (Triticum aestivum), including a necrotrophic pathogen of barley, a hemibiotrophic pathogen of sugar beet and a saprotroph, to evaluate the role of SnTox1 in infection and in protection from wheat chitinases. SnTox1 bound chitin and an SnTox1-green fluorescent fusion protein localized to the mycelial cell wall. Purified SnTox1 induced necrosis in the absence of the pathogen when sprayed on the leaf surface and appeared to remain on the leaf surface while inducing both epidermal and mesophyll cell death. SnTox1 protected the different fungi from chitinase degradation. SnTox1 was sufficient to change the host range of a necrotrophic pathogen but not a hemibiotroph or saprotroph. Collectively, this work shows that SnTox1 probably interacts with a receptor on the outside of the cell to induce cell death to acquire nutrients, but SnTox1 accomplishes a second role in that it protects against one aspect of the defense response, namely the effects of wheat chitinases.
authors.affiliation: Department of Plant Pathology, North Dakota State University, Fargo, ND, 58102, USA.
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Department of Plant Pathology, North Dakota State University, Fargo, ND, 58102, USA.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Department of Plant Pathology, North Dakota State University, Fargo, ND, 58102, USA.
authors.forename: Yong Min
authors.initials: YM
authors.lastname: Kim
authors.affiliation: Northern Crop Science Laboratory, United States Department of Agriculture - Agricultural Research Service, Fargo, ND, 58102, USA.
authors.forename: Justin D
authors.initials: JD
authors.lastname: Faris
authors.affiliation: Biosciences Research Laboratory, United States Department of Agriculture - Agricultural Research Service, Fargo, ND, 58102, USA.
authors.forename: Weilin L
authors.initials: WL
authors.lastname: Shelver
authors.affiliation: Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, the Netherlands.
authors.forename: Pierre J G M
authors.initials: PJ
authors.lastname: de Wit
authors.affiliation: Northern Crop Science Laboratory, United States Department of Agriculture - Agricultural Research Service, Fargo, ND, 58102, USA.
authors.forename: Steven S
authors.initials: SS
authors.lastname: Xu
authors.affiliation: Department of Plant Pathology, North Dakota State University, Fargo, ND, 58102, USA.|Northern Crop Science Laboratory, United States Department of Agriculture - Agricultural Research Service, Fargo, ND, 58102, USA.
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Friesen
mesh_terms: D001203:Ascomycota / Q000166:cytology / Q000254:growth & development / Q000378:metabolism* / Q000472:pathogenicity; D002686:Chitin / Q000378:metabolism; D002688:Chitinases / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D058503:Mesophyll Cells / Q000382:microbiology; D025282:Mycelium / Q000378:metabolism; D018515:Plant Leaves / Q000382:microbiology; D014908:Triticum / Q000201:enzymology* / Q000382:microbiology*; D014774:Virulence
chemical_list: D005656:Fungal Proteins; D002686:Chitin; D049452:Green Fluorescent Proteins; D002688:Chitinases
keywords: Parastagonosopora nodorum; chitin; host-selective toxin; necrotroph; necrotrophic effector; programmed cell death (PCD); wheat (Triticum aestivum) chitinases