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Mécanismes moléculaires impliqués dans la modulation de la production de trichothécènes de type B par Fusarium graminearum en réponse au stress oxydant

Abstract : Fusarium graminearum is a pathogenic fungus responsible for “Fusarium Head Blight”, a diseaseaffecting cereals, including wheat or maize. The fungus can produce toxic secondary metabolitesbelonging to the type B trichothecene family. These metabolites are heat and chemically stablemolecules. These toxins can be found in grains before harvest and no available decontaminationprocess can eliminate or detoxify trichothecenes. The best way to restrict their occurrence is to limittheir biosynthesis. The Tri genes involved in the biosynthetic pathway are clustered and theirregulation is complex. During plant/pathogen interaction, the fungus must cope with pro orantioxidants, involved in plant defense mechanisms. In vitro, prooxidant molecules stimulatetrichothecenes biosynthesis via Tri genes overexpression, whereas antioxidants compounds repress Trigenes expression and toxin accumulation.The transcription factor Fgap1, homologous to Yap1 in yeast and involved in response to oxidativestress, was identified in F. graminearum and its potential role in the regulation of trichothecenesbiosynthesis was investigated. Using recombinant strains, we demonstrated that, in response tooxidative stress, Fgap1 is not only involved in expression of detoxifying activities, but also in themodulation of trichothecene accumulation. Nonetheless, Fgap1 is not involved in response toantioxidant compounds. RNA-seq analysis has been initiated to identify regulatory network involvedin response to redox variations.
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Mathilde Montibus. Mécanismes moléculaires impliqués dans la modulation de la production de trichothécènes de type B par Fusarium graminearum en réponse au stress oxydant. Sciences agricoles. Université Sciences et Technologies - Bordeaux I, 2013. Français. ⟨NNT : 2013BOR14924⟩. ⟨tel-00933710⟩

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