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SESSION 1: FUSARIUM – GENETICS, GENOMICS AND SYSTEMS BIOLOGY
Transcriptomic profiling of fumonisin B biosynthesis
by Fusarium verticillioides
N. Ponts, E. Zehraoui, L. Pinson-Gadais, F. Richard-Forget, C. Barreau
INRA UR1264 MycSA, 71 Avenue Edouard Bourlaux, CS20032, 33882 Villenave d'Ornon Cedex –
France
E-mail: nadia.ponts@bordeaux.inra.fr
The plant fungal pathogen Fusarium verticillioides can infect various plants
worldwide, including maize, and contaminate kernels with mycotoxins of the
fumonisin family. Fumonisins B are stable polyketides that resist agrifood
processing and are classified as potentially carcinogenic. As such, contamination
of food and feeds with these toxic secondary metabolites must be avoided.
Numerous factors influence fumonisins B accumulation on maize, including the
composition of the grains on which Fusarium develops. In particular, several
phenolic compounds were shown to inhibit fumonisin B biosynthesis. Preliminary
analyses showed that free phenolic acids are particularly abundant in immature
grains, i.e., at the onset of toxin production, from cereal cultivars on which
mycotoxins tend to accumulate less.
We tested in vitro the effect of chlorogenic, caffeic, and ferulic acid on fumonisin B
production in F. verticillioides. All three compounds inhibit fumonisin B
accumulation, caffeic acid being the most efficient with that regard. We
investigated the mechanisms by which these phenolic acids may exert their
inhibitory properties and analyzed whole genome expression levels by RNA-seq.
Sequenced reads were mapped to the reference genome of F. verticillioides and
results were analyzed according to the current annotation available at the
Fusarium Comparative Database. Doing so, we identified 175 and 1133 potential
new genes and transcripts, respectively. We also found that the genes involved in
the fumonisins biosynthetic pathway are all inhibited in the presence of any of the
three tested phenolic acids. Finally, we identified sets of genes that are regulated
specifically by a given phenolic acid, and others that follow similar patterns in all
tested conditions. As a whole, our results show a large re-organization of
Fusarium’s transcriptome upon phenolic acid treatment.
Keywords: Fusarium, secondary metabolite, RNA-seq, antioxidant
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