title: The bZIP transcription factor Fgap1 mediates oxidative stress response and trichothecene biosynthesis but not virulence in Fusarium graminearum.
abstract: Redox sensing is of primary importance for fungi to cope with oxidant compounds found in their environment. Plant pathogens are particularly subject to the oxidative burst during the primary steps of infection. In the budding yeast Saccharomyces cerevisiae, it is the transcription factor Yap1 that mediates the response to oxidative stress via activation of genes coding for detoxification enzymes. In the cereal pathogen Fusarium graminearum, Fgap1 a homologue of Yap1 was identified and its role was investigated. During infection, this pathogen produces mycotoxins belonging to the trichothecenes family that accumulate in the grains. The global regulation of toxin biosynthesis is not completely understood. However, it is now clearly established that an oxidative stress activates the production of toxins by F. graminearum. The involvement of Fgap1 in this activation was investigated. A deleted mutant and a strain expressing a truncated constitutive form of Fgap1 were constructed. None of the mutants was affected in pathogenicity. The deleted mutant showed higher level of trichothecenes production associated with overexpression of Tri genes. Moreover activation of toxin accumulation in response to oxidative stress was no longer observed. Regarding the mutant with the truncated constitutive form of Fgap1, toxin production was strongly reduced. Expression of oxidative stress response genes was not activated in the deleted mutant and expression of the gene encoding the mitochondrial superoxide dismutase MnSOD1 was up-regulated in the mutant with the truncated constitutive form of Fgap1. Our results demonstrate that Fgap1 plays a key role in the link between oxidative stress response and F. graminearum secondary metabolism.
authors.affiliation: Institut National de la Recherche Agronomique, Unité de Recherche 1264 MycSA, Villenave d'Ornon, France.
authors.forename: Mathilde
authors.initials: M
authors.lastname: Montibus
authors.affiliation: Institut National de la Recherche Agronomique, Unité de Recherche 1264 MycSA, Villenave d'Ornon, France.
authors.forename: Christine
authors.initials: C
authors.lastname: Ducos
authors.affiliation: Institut National de la Recherche Agronomique, Unité de Recherche 1264 MycSA, Villenave d'Ornon, France.
authors.forename: Marie-Noelle
authors.initials: MN
authors.lastname: Bonnin-Verdal
authors.affiliation: University of Hamburg, Biocenter Klein Flottbek, Department of Molecular Phytopathology and Genetics, Hamburg, Germany.
authors.forename: Jorg
authors.initials: J
authors.lastname: Bormann
authors.affiliation: Institut National de la Recherche Agronomique, Unité de Recherche 1264 MycSA, Villenave d'Ornon, France.
authors.forename: Nadia
authors.initials: N
authors.lastname: Ponts
authors.affiliation: Institut National de la Recherche Agronomique, Unité de Recherche 1264 MycSA, Villenave d'Ornon, France.
authors.forename: Florence
authors.initials: F
authors.lastname: Richard-Forget
authors.affiliation: Institut National de la Recherche Agronomique, Unité de Recherche 1264 MycSA, Villenave d'Ornon, France ; Centre National de la Recherche Scientifique, Unité de Recherche 1264 MycSA, Villenave d'Ornon, France.
authors.forename: Christian
authors.initials: C
authors.lastname: Barreau
mesh_terms: D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D005670:Fusarium / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D015966:Gene Expression Regulation, Fungal / Q000502:physiology*; D018384:Oxidative Stress / Q000502:physiology*; D014255:Trichothecenes / Q000096:biosynthesis*
chemical_list: D050976:Basic-Leucine Zipper Transcription Factors; D005656:Fungal Proteins; D014255:Trichothecenes