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Title: CO-EXPRESSION OF FIFTEEN CONTIGUOUS GENES DELINEATES A FUMONISIN BIOSYNTHETIC GENE CLUSTER IN GIBBERELLA MONILIFORMIS

Author
item Proctor, Robert
item Brown, Daren
item Plattner, Ronald
item Desjardins, Anne

Submitted to: Fungal Genetics and Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/26/2002
Publication Date: 3/1/2003
Citation: Proctor, R., Brown, D.W., Plattner, R.D., Desjardins, A.E. 2003. Co-expression of fifteen contiguous genes delineates a fumonisin biosynthetic gene cluster in gibberella moniliformis. Fungal Genetics and Biology. 38: 237-249. 2003

Interpretive Summary: The fungus Gibberella moniliformes (also known as Fusarium verticillioides) causes stalk and ear rot of corn and produces a group of toxins known as fumonisins. These toxins are of concern because they accumulate in corn infected with the fungus and because they cause several animal diseases, including cancer in rats and mice. Also, there is a correlation between the consumption of fumonisin contaminated corn and human esophageal cancer in some regions of the world where corn is a dietary staple. One objective of our research is to characterize Gibberella moniliformes genes that are involved in fumonisin biosynthesis in order to identify targets that can be exploited in reducing or eliminating fumonisin contamination in corn. In this study, we identified a cluster of 15 fumonisin biosynthetic genes that are located on chromosome 1 of Gibberella moniliformes. Genes in the cluster are turned "on" and "off" in a manner that is correlated with fumonisin production. A better understanding of the mechanism(s) that turn these genes on and off may reveal strategies that can prevent fumonisin production in corn. This research should benefit corn producers by providing them with control strategies that could eliminate or reduce fumonisin contamination in corn.

Technical Abstract: Fumonisins are mycotoxins produced by the maize pathogen Gibberella moniliformis (anamorph Fusarium verticillioides) and have been associated with cancer in experimental rodents. In this study, we determined the nucleotide sequence of a 75-kb region of G. moniliformis DNA and identified 18 heretofore undescribed genes flanking a cluster of five previously identified fumonisin biosynthetic (FUM) genes. Ten of the newly identified genes immediately downstream of the cluster were coregulated with FUM genes and exhibited patterns of expression that were correlated with fumonisin production. BLASTX analyses indicated that the predicted functions of proteins encoded by the 10 genes were consistent with enzyme activities expected for fumonisin biosynthesis or self-protection. These data indicate that the 10 newly identified genes and the previously identified FUM genes constitute a fumonisin biosynthetic gene cluster. However, disruption of three of the new genes, encoding longevity assurance factors and an ABC transporter, had no apparent effect on fumonisin production.