Submitted to: Fungal Genetics Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: March 20, 2007
Publication Date: March 20, 2007
Citation: Proctor, R., Butchko, R.A., Brown, D.W. 2007. Characterization of a putative fusarin mycotoxin biosynthetic gene cluster in fusarium [abstract]. Fungal Genetics Conference. p. 105. Technical Abstract: Fusarium verticillioides is a stalk and ear rot pathogen of maize that can produce the polyketide mycotoxins fumonisins in infected kernels. Although the genetics and biochemistry of fumonisin biosynthesis is relatively well understood in F. verticillioides, little is known about the biosynthesis of other secondary metabolites produced by this fungus, and about whether the regulatory mechanisms that affect fumonisin biosynthesis also affect biosynthesis of other secondary metabolites. To begin to address such issues, we are using microarray analysis to determine whether 15 previously identified F. verticillioides PKS genes (Kroken et al, 2003 PNAS 100:15670-15675) are located in clusters of coordinately regulated genes. To date, the analysis indicates that three of the PKS genes are located in clusters. For example, PKS10, which is required for the biosynthesis of fusarin mycotoxins, and eight contiguous genes adjacent to it, exhibit similar changes in expression over time in liquid GYAM medium. These same eight genes also exhibit relatively high levels of expression on whole maize kernels but low levels on maize embryo tissue. In contrast, other genes in the same chromosomal region do not exhibit such differences in expression. Similar arrangements of PKS10 and the adjacent, coexpressed genes are present in the genomes of F. graminearum and Nectria haematococca. In addition, at least some of the genes next to PKS10 are predicted to encode enzymes with functions expected to be required for fusarin biosynthesis based on the chemical structures of the mycotoxins. Together, the data suggest that PKS10 and some of the genes next to it constitute a fusarin biosynthetic gene cluster.