COMPARATIVE ANALYSIS OF 87,000 EXPRESSED SEQUENCE TAGS FROM THE FUMONISIN-PRODUCING FUNGUS FUSARIUM VERTICILLIOIDES

Authors: Brown, Daren; CHEUNG, FOO - TIGR, ROCKVILLE, MD; Proctor, Robert; Butchko, Robert; ZHENG, LI - TIGR, ROCKVILLE, MD; LEE, YUANDAN - TIGR, ROCKVILLE, MD; UTTERBACK, TERESA - JC VENTER SCI, ROCKVILLE; SMITH, SHANNON - JC VENTER SCI, ROCKVILLE; FELDBLYUM, TAMARA - JC VENTER SCI, ROCKVILLE; Glenn, Anthony - Tony; Plattner, Ronald; Kendra, David; TOWN, CHRISTOPHER - INSTITUTE FOR GENOMIC; WHITELAW, CATHERINE - INSTITUTE FOR GENOMIC

Submitted to: Fungal Genetics and Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/6/2005
Publication Date: 8/11/2005
Citation: Brown, D.W., Cheung, F., Proctor, R., Butchko, R.A., Zheng, L., Lee, Y., Utterback, T., Smith, S., Feldblyum, T., Glenn, A.E., Plattner, R.D., Kendra, D.F., Town, C.D., Whitelaw, C.A. 2005. Comparative analysis of 87,000 expressed sequence tags from the fumonisin-producing fungus Fusarium verticillioides. Fungal Genetics and Biology. 42:848-861.

Interpretive Summary: Fusarium verticillioides is a fungus that normally lives in harmony with corn, but for unknown reasons, it can sometimes cause a significant amount of damage. In addition, this fungus can synthesis a family of toxins called fumonisins which can be found contaminating grain destined for both animal and human consumption. Fumonisins cause a variety of animal diseases and have been associated with neural tube defects and cancer in humans. A major focus of our labs is to identify new ways to reduce or eliminate fumonisin contamination of corn. We are using the genomic technology of expressed sequence tags (ESTs) to help identify fungal genes that may be important in toxin synthesis as well as the fungal-plant interaction. We believe that a better understanding of these processes will allow us to meet our goal. In this study, we identified a number of genes that are potentially involved. We have also found evidence for a novel process involving alternatively spliced introns that we believe is important for regulating toxin synthesis. And finally, we have identified a new fumonisin gene that we believe is required for toxin biosynthesis. We are now applying gene-knockout technology to determine the biological role, if any, of many of these genes. These results will enable us to develop new strategies to limit toxin contamination of corn and disease impact on yield.

Technical Abstract: Fusarium verticillioides (teleomorph Gibberella moniliformis) is a pathogen of maize worldwide and produces fumonisins, a family of mycotoxins that have been associated with several animal diseases as well as cancer in humans. In this study, we sought to identify fungal genes that affect fumonisin production and/or the plant-fungal interaction. We generated over 87,000 expressed sequence tags (ESTs) from nine different cDNA libraries that correspond to 11,119 unique sequences and are estimated to represent 80% of the genomic complement of genes. A comparative analysis of the libraries showed that all 15 genes in the fumonisin gene cluster were differentially expressed. In addition, nine candidate fumonisin regulatory genes and a number of genes that may play a role in plant-fungal interaction were identified. Analysis of over 700 FUM gene transcripts from five different libraries provided evidence for transcripts with unspliced introns and spliced introns with alternative 3' splice sites. The abundance of the alternative splice forms and the frequency with which they were found for genes involved in the biosynthesis of a single family of metabolites as well as their differential expression suggests they may have a biological function. Finally, analysis of an EST that aligns to genomic sequence between FUM12 and FUM13 provided evidence for a previously unidentified gene (FUM20) in the FUM gene cluster.