Molecular biology of Fusarium mycotoxins ☆ A.E. Desjardins ⁎ , R.H. Proctor National Center for Agricultural Utilization Research, United States Department of Agriculture, Peoria, Illinois, 61604, USA Abstract As the 20th century ended, Fusarium mycotoxicology entered the age of genomics. With complete genomes of Fusarium graminearum and F. verticillioides and several Fusarium gene expression sequence databases on hand, researchers worldwide are working at a rapid pace to identify mycotoxin biosynthetic and regulatory genes. Seven classes of mycotoxin biosynthetic genes or gene clusters have been identified in Fusarium to date; four are polyketide synthase gene clusters for equisetin, fumonisins, fusarins, and zearalenones. Other Fusarium mycotoxin biosynthetic genes include a terpene cyclase gene cluster for trichothecenes, a cyclic peptide synthetase for enniatins, and a cytochrome P450 for butenolide. From the perspective of the United States Department of Agriculture, the ultimate goal of research on Fusarium molecular biology is to reduce mycotoxins in cereal grains. With this goal in mind, efforts have focused on identifying aspects of mycotoxin biosynthesis and regulation that can be exploited for mycotoxin control. New information on fungal and plant genomes and gene expression will continue to provide information on genes important for fungal-plant interactions and to facilitate the development of targeted approaches for breeding and engineering crops for resistance to Fusarium infection and mycotoxin contamination. Published by Elsevier B.V. Keywords: Fusarium; Gene cluster; Mycotoxin 1. Fusarium mycotoxins As the 20th century ended, Fusarium mycotoxicology entered the age of genomics. Our research group at the United States Department of Agriculture reported the discovery of the trichothecene biosynthetic gene cluster in F. sporotrichioides in 1993 and the fumonisin biosynthetic gene cluster in F. verticil- lioides in 1999. During the 1990s, research groups in Germany cloned genes for biosynthesis of the mycotoxin enniatin and for other Fusarium secondary metabolites. During this decade, gene expression sequence databases of various mycotoxigenic Fusar- ium species also became available. The field of Fusarium genomics was accelerated when the United States Department of Agriculture and National Science Foundation jointly supported the sequencing and public release of the complete genomes of F. graminearum in 2003 and of F. verticillioides in 2006 (Broad Institute/MIT Center for Genome Research [www.broad.mit.edu/ annotation/genome/fusarium_graminearum/Home.html][www. broad.mit.edu/annotation/genome/fusarium_verticillioides/Home. html]). Access to these Fusarium genomes revealed the presence of dozens of candidate genes for polyketide synthases, non- ribosomal peptide synthetases, terpene cyclases, and other types of enzymes that synthesize mycotoxins and other biologically active metabolites. Comparison of DNA sequences per se cannot supply details of mycotoxin biosynthetic pathways; this information must be obtained by appropriate experimentation. Fortunately, Fusar- ium species are highly amenable to the techniques of biochemistry, classical genetics, and molecular genetics necessary to validate function of candidate genes. With two complete Fusarium genomes and several Fusarium gene expression sequence databases on hand, researchers worldwide are working at a rapid pace to identify biosynthetic and regulatory genes for individual mycotoxins and other biologically active metabolites. This brief overview begins with molecular biology of three major classes of mycotoxins that have been proven to cause animal disease outbreaks: trichothecenes, fumonisins, and zearalenones. The review continues with minor mycotoxins, including metabo- lites that are carcinogenic or toxic in experimental systems (beauvericin and enniatins, equisetin, fusarins), and metabolites Available online at www.sciencedirect.com International Journal of Food Microbiology 119 (2007) 47 – 50 www.elsevier.com/locate/ijfoodmicro ☆ Disclaimer: Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U. S. Department of Agriculture. ⁎ Corresponding author. Tel.: +1 309 6816378; fax: +1 309 681 6665. E-mail address: anne.desjardins@ars.usda.gov (A.E. Desjardins). 0168-1605/$ - see front matter. Published by Elsevier B.V. doi:10.1016/j.ijfoodmicro.2007.07.024