Submitted to: Fungal Genetics and Biology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/19/2012
Publication Date: 7/1/2012
Publication URL: http://handle.nal.usda.gov/10113/60425
Citation: Brown, D.W., Butchko, R.A., Busman, M., Proctor, R. 2012. Identification of gene clusters associated with fusaric acid, fusarin, and perithecial pigment production in Fusarium verticillioides. Fungal Genetics and Biology. 49(7):521-532. Interpretive Summary: Fusarium verticillioides is a fungus that causes disease in corn that can result in contamination of corn and corn products with a number of fungal toxins (mycotoxins) including fumonisins, fusaric acid and fusarins. Identification of the genes responsible for fumonisin production has advanced efforts to understand their role in interactions between the fungus and plant hosts, and is critical to developing novel strategies to limit toxin contamination of grain. In the current study, we used microarray technology, representing the entire F. verticillioides gene set, to identify the genes responsible for the synthesis of fusaric acid and fusarin mycotoxins. This research is critical to assessing the role of these toxins in plant disease, and will be of use to plant pathologists, plant breeders, and other scientists focused on the development of novel strategies to limit or control toxin contamination of grain in order to keep our food supply safe.
Technical Abstract: The genus Fusarium is of concern to agricultural production and food/feed safety because of its ability to cause crop disease and to produce mycotoxins, secondary metabolites (SMs) that are toxic to humans and other animals. Understanding the genetic basis for production of mycotoxins and other SMs can provide insights into connections between SM production and plant disease as well as potential solutions to limit crop disease and mycotoxin contamination. In fungi, SM biosynthetic genes are typically located adjacent to one another in clusters of co-expressed genes. Such clusters include a core gene, responsible for synthesis of an initial chemical, and several genes responsible for either chemical modifications, transport, or the regulation of cluster gene transcription. Fusarium verticillioides is one of the most common pathogens of maize and produces fumonisins, a family of mycotoxins of food/feed safety concern worldwide. Here, we employed whole genome expression analysis and utilized existing knowledge of polyketide synthase (PKS) genes, a common cluster core gene, to identify three novel clusters of co-expressed genes in F. verticillioides. Functional analysis of the PKS genes linked the clusters to production of three known Fusarium SMs, a violet pigment in sexual fruiting bodies (perithecia) and the mycotoxins fusarin C and fusaric acid. The results indicate that microarray analysis of RNA derived from culture conditions that induce differential gene expression can be an effective tool for identifying SM biosynthetic gene clusters.