Identification and functional characterization of cryptic secondary metabolite gene clusters and comparative genomics in Fusarium fujikuroi

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Species of the genus Fusarium are well known as serious plant pathogens and producers of several harmful mycotoxins, such as fumonisins, moniliformin, zearalenone, fusarin C, fusaric acid, bikaverin, equisetin, and beauvericin. With the complete genome sequence of the maize pathogen F. verticillioides at hand, and the intended genome sequencing of the biotechnologically important (gibberellin production) fungus F. fujikuroi, we will be able to identify the genes (clusters) for biosynthesis of two harmful polyketide mycotoxins: moniliformin and fusarin C. To date, none of the moniliformin biosynthetic genes is known from any Fusarium species, and only one fusarin C biosynthetic gene, the hybridpolyketide synthase/ non ribosomal peptidsynthase (PKS/NRPS)-encoding gene, has been identified in Fusarium moniliformis. In order to reduce the health risk of these mycotoxins in food, feed and biotechnologically produced gibberellin preparations, we are planning to identify the yet unknown genes and pathways for biosynthesis of fusarin C and moniliformin in F. verticillioides and F. fujikuroi. To identify the moniliformin-specific PKS gene, we will generate knock-out mutants for candidate PKS genes in a moniliformin-producing F. fujikuroi strain and identify a moniliformin-minus mutant. For fusarin C, we will delete more putative biosynthetic genes adjacent to the already known PKS/NRPS gene and identify the intermediates in all knock-outs. Transcriptional regulation of pathway genes will be studied under different conditions (nutrient starvations, ambient pH), and the impact of global regulators on gene expression will be examined.