Submitted to: Fungal Genetics and Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/10/2001
Publication Date: N/A
Citation: N/A Interpretive Summary: The fungus Fusarium verticillioides causes ear and stalk rot of corn and produces a group of toxins known as fumonisins. These toxins are of concern because the accumulate in corn infected with the fungus and they cause a number of fatal animal diseases including cancer in rats and mice. We are currently characterizing genes involved in the biosynthesis of fumonisins in order to identify strategies for reducing or eliminating fumonisin contamination in corn. In this study, we identified four new fumonisin biosynthetic genes that are located on chromosome 1 of F. verticillioides adjacent to the previously described fumonisin biosynthetic gene, FUM5. In the fungus, the four genes are turned "on" and "off" in a manner that is correlated with fumonisin production. In addition, inactivation of one of the genes (FUM6), blocks fumonisin production in F. verticillioides. Understanding the mechanism(s) that turn these genes on and off may provide clues for controlling fumonisin contamination in corn.
Technical Abstract: Fumonisins are mycotoxins that cause several fatal animal diseases, including cancer in rats and mice. These toxins are produced by the maize pathogen Fusarium verticillioides and can accumulate in maize infected with the fungus. We have identified four F. verticillioides genes (FUM6, FUM7, FUM8, and FUM9) adjacent to FUM5, a previously identified polyketide synthase gene that is required for fumonisin biosynthesis. Gene disruption analysis revealed that FUM6 is required for fumonisin production and Northern blot analysis revealed that expression of the four new genes is correlated with fumonisin production. Nucleotide sequence analysis indicated that the predicted FUM6 translation product is most similar to cytochrome P450 monooxygenase-P450 reductase fusion proteins, while the predicted products of FUM7, FUM8, and FUM9 are most similar to type III alcohol dehydrogenase, class-II alpha-aminotransferases and dioxygenases, respectively. Together, these data indicate that FUM5 through FUM9 form part of a fumonisin biosynthetic gene cluster in F. verticillioides.