title: CLNR1, the AREA/NIT2-like global nitrogen regulator of the plant fungal pathogen Colletotrichum lindemuthianum is required for the infection cycle.
abstract: Nitrogen starvation is generally assumed to be encountered by biotrophic and hemibiotrophic plant fungal pathogens at the beginning of their infection cycle. We tested whether nitrogen starvation constitutes a cue regulating genes that are required for pathogenicity of Colletotrichum lindemuthianum, a fungal pathogen of common bean. The clnr1 (C. lindemuthianumnitrogen regulator 1) gene, the areA/nit-2 orthologue of C. lindemuthianum, was isolated. The predicted CLNR1 protein exhibits high amino acid sequence similarities with the AREA and NIT2 global fungal nitrogen regulators. Targeted clnr1- mutants are unable to use a wide array of nitrogen sources, indicating that clnr1 is the C. lindemuthianum major nitrogen regulatory gene. The clnr1- mutants are non-pathogenic, although few anthracnose lesions seldom occur on whole plantlets. Surprisingly, cytological analysis reveals that the clnr1- mutants are not disturbed from the penetration stage until the end of the biotrophic phase, but that they are impaired during the setting up of the necrotrophic phase. Thus, through CLNR1, nitrogen starvation constitutes a cue for the regulation of genes that are compulsory for this stage of the C. lindemuthianum infection process. Additionally, clnr1- mutants complemented with the Aspergillus nidulans areA gene are fully pathogenic, indicating that areA is able to activate the C. lindemuthianum suited genes, normally under the control of clnr1.
authors.affiliation: Laboratoire de Phytopathologie Moléculaire, Institut de Biotechnologie des Plantes, Bâtiment 630, Université de Paris-Sud XI, 91405 Orsay Cedex, France. pellier@ibp.u.psud.fr
authors.forename: Anne-Laure
authors.initials: AL
authors.lastname: Pellier
authors.forename: Richard
authors.initials: R
authors.lastname: Laugé
authors.forename: Claire
authors.initials: C
authors.lastname: Veneault-Fourrey
authors.forename: Thierry
authors.initials: T
authors.lastname: Langin
mesh_terms: D000595:Amino Acid Sequence; D001233:Aspergillus nidulans / Q000235:genetics / Q000378:metabolism; D020231:Colletotrichum / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity*; D007887:Fabaceae / Q000166:cytology / Q000382:microbiology / Q000502:physiology; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D009154:Mutation; D009584:Nitrogen / Q000378:metabolism; D009586:Nitrogen Fixation / Q000235:genetics*; D016415:Sequence Alignment; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: C079728:AreA protein, Aspergillus nidulans; D005656:Fungal Proteins; D014157:Transcription Factors; D009584:Nitrogen