|Hohn, Thomas - NOVARTIS SEEDS, RTP, NC|
Submitted to: Fungal Genetics Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: March 28, 1999
Publication Date: N/A
Technical Abstract: Fumonisins are mycotoxins produced by the maize pathogen Gibberella fujikuroi mating population A (MP-A) and related fungi. These toxins are associated with mycotoxicoses in both humans and animals. We employ chemical, biochemical, and conventional and molecular genetic approaches in the study of fumonisin biosynthesis and the role of these toxins in G. fujikuroi. Recently, we used a PCR approach to isolate a polyketide synthase (PKS) gene involved in fumonisin biosynthesis in G. fujikuroi. Nucleotide sequence analysis of this gene, designated FUM5, indicated it has a 7.8 kb coding region interrupted by 5 introns. The predicted translation product of FUM5 had conserved amino acid sequences indicative of the ketoacyl synthase, acyl transferase, ketoacyl reductase, dehydratase, enoyl reductase, and acyl carrier protein domains that are required for the biosynthesis of polyketides. Transformation of a cosmid clone that included FUM5 into various strains of G. fujikuroi increased fumonisin production 3 to 18 fold in three strains and restored wild-type production in a fumonisin-nonproducing strain. Disruption of FUM5 reduced fumonisin production by over 99% in G. fujikuroi MP-A. These results indicate that FUM5 is a PKS gene required for fumonisin biosynthesis.