EFS12- Book of abstracts - Contact

SESSION 1: FUSARIUM – GENETICS, GENOMICS AND SYSTEMS BIOLOGY
Fgap1-mediated response to oxidative stress in
trichothecene-producing Fusarium graminearum.
M. Montibus 1 , N. Ponts 1 , E. Zehraoui 1 , C. Ducos 1 , F. Richard-Forget 1 , C.
Barreau 1 .
1 INRA, UR1264-MycSA, 71 avenue Edouard Bourlaux, CS20032, F-33883 Villenave d’Ornon Cedex.
E-mail: mathilde.montibus@bordeaux.inra.fr
The filamentous fungus Fusarium graminearum infects cereals and corn. It is one
of the main causal agent of “Fusarium Head Blight” and “Maize Ear Rot”. During
infection, it produces mycotoxins belonging to the trichothecenes family that
accumulate in the grains. Although the biosynthetic pathway involving specific Tri
genes has been elucidated, the global regulation of toxin biosynthesis remains
enigmatic. It is now established that oxidative stress modulates the production of
toxins by F. graminearum. H2O2 added in liquid cultures increases the expression
of Tri genes involved in the biosynthesis of type B trichothecenes as well as
downstream trichothecene accumulation.
In the yeast Saccharomyces cerevisiae, the transcription factor Yap1p mediates
response to oxidative stress via nuclear localization and activation of genes
coding for detoxification enzymes. In this study, we investigate the role of Yap1p
homolog in F. graminearum, Fgap1, in response to oxidative stress and its
eventual role in the regulation of trichothecene production.
A deleted mutant and a strain expressing a constitutively activated form of the
Fgap1 factor in F. graminearum were constructed. In the presence of oxidative
stress by H2O2, Tri genes expression levels and trichothecene production by the
strain lacking the gene Fgap1 are enhanced, whereas Tri genes expression and
toxin accumulation are severely diminished in the mutant strain expressing Fgap1
constitutively. Expression profiles of genes encoding detoxification enzymes
potentially controlled by Fgap1 were further analyzed by qRT-PCR. These results
are currently being deepened by a transcriptomic approach. The involvement of
Fgap1 in other types of stress responses has also been investigated. In particular,
cadmium and osmotic stress affect growth in the deleted strain.
Keywords: Fusarium graminearum, secondary metabolites, oxidative stress,
Fgap1
33