title: A class III histidine kinase acts as a novel virulence factor in Botrytis cinerea.
abstract: Filamentous ascomycetes contain large numbers of histidine kinases (HK) that belong to eleven classes. Members of class III from different species were previously shown to be involved in osmoregulation and resistance to dicarboximide and phenylpyrrole fungicides. We have inactivated the gene encoding the single group III HK, BOS1, in the economically important plant pathogen Botrytis cinerea. BOS1 inactivation had pleiotropic effects on the fungus. Besides the expected osmosensitivity and resistance to fungicides, null mutants presented additional characteristics indicating that BOS1 is necessary for normal macroconidiation and full virulence. On standard culture media, null mutants very rarely formed conidiophores and those few conidiophores failed to produce conidia. This defect could be partially restored with 1 M sorbitol, suggesting that another BOS1-independent signal cascade may be involved in macroconidiation. The mutants were not found to be hypersensitive to various oxidative stresses but were more resistant to menadione. Finally, pathogenicity tests showed that bos1-null mutants were significantly reduced in the ability to infect host plants. Appressorium morphogenesis was not altered; however, in planta growth was severely reduced. To our knowledge, this is the first class III HK characterized as a pathogenicity factor in a plant-pathogenic ascomycete.
authors.affiliation: Unité de Phytopathologie et Méthodologies de la Détection, Institut National de la Recherche Agronomique, Rte de St-Cyr, 78026 Versailles, France. viaud@versailles.inra.fr
authors.forename: Muriel
authors.initials: M
authors.lastname: Viaud
authors.forename: Sabine
authors.initials: S
authors.lastname: Fillinger
authors.forename: Weiwei
authors.initials: W
authors.lastname: Liu
authors.forename: Jai Santosh
authors.initials: JS
authors.lastname: Polepalli
authors.forename: Pascal
authors.initials: P
authors.lastname: Le Pêcheur
authors.forename: Aditya Reddy
authors.initials: AR
authors.lastname: Kunduru
authors.forename: Pierre
authors.initials: P
authors.lastname: Leroux
authors.forename: Laurent
authors.initials: L
authors.lastname: Legendre
mesh_terms: D015139:Blotting, Southern; D020171:Botrytis / Q000187:drug effects / Q000235:genetics* / Q000472:pathogenicity; D003470:Culture Media / Q000494:pharmacology; D025141:Drug Resistance, Fungal / Q000235:genetics; D007887:Fabaceae / Q000382:microbiology; D005656:Fungal Proteins / Q000235:genetics; D005659:Fungicides, Industrial / Q000494:pharmacology; D000071677:Histidine Kinase; D018551:Solanum lycopersicum / Q000382:microbiology; D027845:Malus / Q000382:microbiology; D008957:Models, Genetic; D009154:Mutation / Q000235:genetics; D010935:Plant Diseases / Q000382:microbiology; D018515:Plant Leaves / Q000382:microbiology; D011494:Protein Kinases / Q000235:genetics*; D013172:Spores, Fungal / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D014774:Virulence / Q000235:genetics; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D003470:Culture Media; D005656:Fungal Proteins; D005659:Fungicides, Industrial; D037521:Virulence Factors; D011494:Protein Kinases; D000071677:Histidine Kinase