Study of factors affecting fumonisin biosynthesis in Fusarium verticillioides: analysis of FUM1 expression under in vitro conditions and during early steps of maize colonization

Fumonisins are a family of mycotoxins (produced by the Ascomycete fungus Gibberella moniliformis, anamorph Fusarium verticillioides) that contaminate maize and maize-based products and cause great concern for human and animal health. The real role played by fumonisins in pathogenesis and fungal fitness in general has been long controversial, although it is clear that they are phytotoxic. A better comprehension of the molecular mechanisms regulating their production could help clearing this point and preventing kernel contamination. In all eukaryotic organisms, acetylation of core histones and DNA methylation degree play a key role in the regulation of transcription, along with promoter regions. To assess the possibility that rthese epigenetic factors may be linked to fumonisin production, we observed the expression of a key biosynthetic gene (FUM1) in several strains of F. verticillioides after treatment with a histone deacetylase inhibitor, and investigated the methylation of FUM1 promoter under fumonisin-inducing and non-inducing conditions. Moreover we compared the activity of the endogenous FUM1 promoter (pFUM1) with that of the same region driving the ectopic expression of a transgene (GFP) after random insertion in other points of the genome in transgenic F. verticillioides strains expressing the pFUM1::GFP cassette. These are being tested for pFUM1 activity upon maize infection and in fumonisin-inducing and non-inducing conditions, to assess whether the FUM1 and GFP transcripts accumulate differently in dependence of the position of the corresponding coding and regulatory regions in the genome.