FUM and BIK gene expression contribute to describe fumonisin and bikaverin synthesis in Fusarium verticillioides.

Fusarium verticillioides is a maize pathogen that produces toxic secondary metabolites, including fumonisins and bikaverin. The regulation of biosynthetic gene expression and the production of these metabolites are not fully understood and in this study we investigated the influence of water activity (0.955 and 0.990) on the expression of 5 genes (FUM3-FUM8-FUM13-FUM14 and BIK1) in F. verticillioides strains after 14 and 21days incubation. Fumonisin production and biosynthetic gene expression were greatest at a(w)=0.990, and the same trend was observed for bikaverin production, and BIK1 expression. FUM3 and FUM14 were the most highly expressed genes and were positively correlated with the production of FB(1), FB(2) and FB(3). When FUM14 is more highly expressed than FUM3 the amount of FB(3) quantified is higher with respect to FB(1); this could be explained by the role of FUM3 in the hydroxylation of FB(3) to FB(1).