title: Comparative chemical screening and genetic analysis reveal tentoxin as a new virulence factor in Cochliobolus miyabeanus, the causal agent of brown spot disease on rice.
abstract: Brown spot disease, caused by Cochliobolus miyabeanus, is currently considered to be one of the most important yield reducers of rice (Oryza sativa L.). Despite its agricultural importance, little is known about the virulence mechanisms deployed by the fungus. Therefore, we set out to identify novel virulence factors with a role in disease development. This article reports, for the first time, the production of tentoxin by C. miyabeanus as a virulence factor during brown spot disease and the identification of the non-ribosomal protein synthetase (NRPS) CmNps3, responsible for tentoxin biosynthesis. We compared the chemical compounds produced by C. miyabeanus strains differing in virulence ability using ultra-high-performance liquid chromatography (UHPLC) coupled to high-resolution Orbitrap mass spectrometry (HRMS). The production of tentoxin by a highly virulent strain was revealed by principal component analysis of the detected ions and confirmed by UHPLC coupled to tandem-quadrupole mass spectrometry (MS/MS). The corresponding NRPS was identified by in silico genome analysis and confirmed by gene deletion. Infection tests with wild-type and Cmnps3 mutants showed that tentoxin acts as a virulence factor and is correlated with chlorosis development during the second phase of infection. Although rice has previously been classified as a tentoxin-insensitive plant species, our data demonstrate that tentoxin production by C. miyabeanus affects symptom development.
authors.affiliation: Department of Crop Protection, Laboratory of Phytopathology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, BE-9000, Ghent, Belgium.
authors.forename: Lieselotte
authors.initials: L
authors.lastname: De Bruyne
authors.affiliation: Department of Bio-analysis, Laboratory of Food Analysis, Faculty of Pharmaceutical Sciences, Ghent University, BE-9000, Ghent, Belgium.
authors.forename: Christof
authors.initials: C
authors.lastname: Van Poucke
authors.affiliation: Department of Bio-analysis, Laboratory of Food Analysis, Faculty of Pharmaceutical Sciences, Ghent University, BE-9000, Ghent, Belgium.
authors.forename: Diana Jose
authors.initials: DJ
authors.lastname: Di Mavungu
authors.affiliation: Section of Plant Pathology & Plant-Microbe Biology, School of Integrative Plant Science, Cornell University, 14850, Ithaca, NY, USA.|Department of Biology, Faculty of Science, University Putra Malaysia, 43400, Serdang, Selangor, Malaysia.
authors.forename: Nur Ain Izzati Mohd
authors.initials: NA
authors.lastname: Zainudin
authors.affiliation: Department of Veterinary Public Health and Food Safety, Laboratory of Chemical Analysis, Faculty of Veterinary Medicine, Ghent University, BE-9000, Ghent, Belgium.
authors.forename: Lynn
authors.initials: L
authors.lastname: Vanhaecke
authors.affiliation: Department of Crop Protection, Laboratory of Phytopathology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, BE-9000, Ghent, Belgium.
authors.forename: David
authors.initials: D
authors.lastname: De Vleesschauwer
authors.affiliation: Section of Plant Pathology & Plant-Microbe Biology, School of Integrative Plant Science, Cornell University, 14850, Ithaca, NY, USA.
authors.forename: B Gillian
authors.initials: BG
authors.lastname: Turgeon
authors.affiliation: Department of Bio-analysis, Laboratory of Food Analysis, Faculty of Pharmaceutical Sciences, Ghent University, BE-9000, Ghent, Belgium.
authors.forename: Sarah
authors.initials: S
authors.lastname: De Saeger
authors.affiliation: Department of Crop Protection, Laboratory of Phytopathology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, BE-9000, Ghent, Belgium.
authors.forename: Monica
authors.initials: M
authors.lastname: Höfte
mesh_terms: D001203:Ascomycota / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity; D002851:Chromatography, High Pressure Liquid; D017124:Conserved Sequence; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D005800:Genes, Fungal; D012275:Oryza / Q000382:microbiology*; D010456:Peptides, Cyclic / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D010935:Plant Diseases / Q000382:microbiology*; D015203:Reproducibility of Results; D017386:Sequence Homology, Amino Acid; D013172:Spores, Fungal / Q000502:physiology; D053719:Tandem Mass Spectrometry; D037521:Virulence Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D010456:Peptides, Cyclic; D037521:Virulence Factors; C003384:tentoxin
keywords: Bipolaris oryzae; Cochliobolus miyabeanus; Oryza sativa L.; brown spot disease; plant-pathogen interactions; rice; tentoxin