ARS | Publication request: Genomic analysis of Fusarium verticillioides

Submitted to: International Mycotoxin Symposium
Publication Type: Abstract
Publication Acceptance Date: November 7, 2006
Publication Date: November 9, 2006
Citation: Brown, D.W., Butchko, R.A., Busman, M., Kendra, D.F., Proctor, R. 2006. Genomic analysis of Fusarium verticillioides [abstract]. 10th U.S. Japan Cooperative Program in Natural Resources (UJNR) International Symposium on Toxic Microorganisms. Talk #8.

Technical Abstract: Fusarium verticillioides (teleomorph Gibberella moniliformis) is generally an endophyte of maize throughout the world but, on some occasions, it is a pathogen causing disease of ears, stalks and seedlings. Either as an endophyte or pathogen, this fungus can also synthesize fumonisins, a family of mycotoxins structurally similar to the sphingolipid sphinganine. Fumonisins are often found in diseased tissue and sometimes in maize kernels with little-to-no disease symptoms. Fumonisin ingestion has been associated with a number of animal diseases, including cancer, and has been epidemiologically associated with human esophageal cancer in some regions of the world. All of these effects are likely mediated through the ability of fumonisin to inhibit the enzyme ceramide synthase and thereby disrupt sphingolipid metabolism. One of the primary goals of our labs is to eliminate fumonisins contamination of maize and maize products in order to remove them from the animal and human food chain. We believe that understanding how and why these toxins are made, as well as understanding the F. verticillioides-maize disease process, will allow us to develop novel strategies to limit tissue destruction (rot) and toxin production. Fungal genomic information provides powerful tools to identify and examine specific processes. Genomic tools currently available for F. verticillioides include an 8X genomic sequence from the Broad Institute, an Expressed Sequence Tag (EST) collection, managed by The Institute for Genomics Research (TIGR), and a limited number of NimbleGen Systems, Inc. (Madison, WI) microarrays, managed by the USDA. We are using a combination of genomic sequence data and microarrays to identify F. verticillioides¿ structural and regulatory genes involved in the biosynthesis of fungal toxins, in virulence factors, and in other elements involved in plant pathogenesis. The first generation NimbleGen microarray is based on EST sequence data and contains 15,844 probe sets that represent over 11,126 different genes. The first microarray experiment we conducted involved cultures of wild-type F. verticillioides strain M-3125 in the liquid fumonisin production medium, GYAM, for 12, 24, 48, 72, 96 and 120 hrs. We have taken three approaches to mine the microarray data: identify genes co-expressed with fumonisin biosynthetic genes, identify genes co-expressed and flanking polyketide synthase genes, and examine differential expression of transcripts with differential excision of introns. Taken together, these different approaches demonstrate the power of microarray technology to provide information on a large number of biological processes. We are currently developing a second generation F. verticillioides NimbleGen microarray based on gene sequences derived from EST and genomic sequence data.