Submitted to: International Symposium of Mycotoxicology Meeting
Publication Type: Abstract Only
Publication Acceptance Date: September 10, 1999
Publication Date: N/A
Technical Abstract: Fumonisins are mycotoxins that are produced in maize by the fungus G. fujikuroi mating population A (MP-A). These toxins are of concern because they are carcinogens and associated with several animal diseases. In addition, there is an epidemiological correlation between the consumption of fumonisin contaminated maize and human esophageal cancer in some areas of the world. A major objective of our research is to elucidate the role of fumonisins in the life cycle of G. fujikuroi MP-A. To address this objective, we are isolating genes involved in fumonisin biosynthesis. We isolated one such gene (FUM5) via PCR with cDNA templates and degenerate primers. The predicted translation product of FUM5 is 2607 amino acids in length and exhibits high levels of similarity to bacterial and fungal polyketide synthases. Inactivation of FUM5 via gene disruption reduces fumonisin production by over 99% in G. fujikuroi MP-A. These data are consistent with FUM5 encoding a PKS that catalyzes the synthesis of the fumonisin backbone. We have also identified another gene next to FUM5 that exhibits similarity to cytochrome P450 monooxygenase genes. Strains of G. fujikuroi MP-A in which these and other fumonisin biosynthetic genes have been inactivated should be useful in determining whether fumonisins are required for high levels of virulence, systemic colonization, or survival on crop debris.