Submitted to: International Congress of Mycology Proceedings and Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 1, 2002
Publication Date: August 1, 2002
Citation: Proctor, R., Plattner, R.D., Desjardins, A.E., Butchko, R.A., Brown, D.W. 2002. Discontinuous distribution of the fumonisin biosynthetic gene cluster in fusarium. International Congress of Mycology Proceedings and Abstracts. Technical Abstract: Fumonisins are polyketide mycotoxins produced by Fusarium verticillioides, one of the most common ear and stalk rot pathogens of maize. Consumption of fumonisins has been associated epidemiologically with esophageal cancer in humans and experimentally with kidney and liver cancer in rodents. We used nucleotide sequence and expression analyses to identify a cluster of fifteen fumonisin biosynthetic genes (FUM) in F. verticillioides. All fifteen genes were co-regulated and their expression was correlated with fumonisin production. BLASTX sequence comparisons suggested that most of the FUM genes encode enzymes with the kinds of activities expected to be necessary for fumonisin biosynthesis. Disruption of four of these genes, encoding a polyketide synthase, an aminotransferase, and two cytochrome P450 monooxygenases, either blocked fumonisin production or changed the kinds of fumonisins produced. Disruption of four other FUM genes did not alter fumonisin production. Three of the latter genes encode proteins (i.e. an ABC transporter and two longevity assurance factors) that may help F. verticillioides cope with the toxic effects of fumonisins. Efforts are underway to determine more precisely the roles these genes play in fumonisin biosynthesis. We used four F. verticillioides FUM genes as hybridization probes to examine the distribution of FUM genes in other species of Fusarium. In 23 species examined, the genes were detected only in F. nygamai, which is closely related to F. verticillioides, and in F. anthophilum, F. fujikuroi and F. proliferatum, which are more distantly related. These data indicate a discontinuous distribution of FUM genes in Fusarium.