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Title: CHARACTERIZATION OF A FUSARIUM 2-GENE CLUSTER INVOLVED IN TRICHOTHECENE C-8 MODIFICATION

Author
item Brown, Daren
item Proctor, Robert
item Dyer, Rex
item Plattner, Ronald

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/24/2003
Publication Date: 12/6/2003
Citation: BROWN, D.W., PROCTOR, R., DYER, R.B., PLATTNER, R.D. CHARACTERIZATION OF A FUSARIUM 2-GENE CLUSTER INVOLVED IN TRICHOTHECENE C-8 MODIFICATION. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY. 2003. v. 51. p. 7936-7944.

Interpretive Summary: Fusarium Head Blight (in wheat) and corn ear rot can produce trichothecenes. Fusarium sp. synthesizes a variety of trichothecene mycotoxins which can be found in human and animal feeds. Trichothecenes are potent inhibitors of eukaryotic protein synthesis and as such are a significant agricultural problem due to their detrimental affect on human and animal health. We are studying the genes involved in the synthesis of trichothecenes in order to identify strategies for reducing or eliminating fungal infection and trichothecene contamination in wheat and corn. In this study, we describe a new trichothecene gene from F. sporotrichioides that is not located near previously described trichothecene genes in the fungal genome. The gene is a member of a large gene family called cytochrome P450s and is required for adding an oxygen molecule to carbon 8 on the trichothecene nucleus. The discovery of this gene could significantly impact our understanding of the development of Fusarium trichothecene structural diversity and may lead to a better understanding of how the synthesis of these materials are regulated.

Technical Abstract: The Fusarium trichothecenes T-2 toxin and deoxynivalenol (DON) are potent inhibitors of eukaryotic protein synthesis and are a significant agricultural problem. Three co-regulated loci are required for T-2 toxin synthesis by F. sporotrichioides. The core-trichothecene gene cluster consists of 12 genes (Tri3-Tri14) while the second locus consists of a single gene (Tri101). The third loci was recently partially described and encodes 1 to 2 biosynthetic enzymes and a putative regulatory gene. Here, we describe a detailed characterization of this locus. Located adjacent to Tri1 is Tri16 which is required for esterification of the C-8 hydroxyl. A putative regulatory gene, also adjacent to Tri1, is not required for T-2 toxin synthesis. The genomic sequence of F. graminearum (a DON producer) contains a putative functional Tri1 and a non-functional Tri16. The presence of Tri16 pseudogene is consistent with the chemical structure of DON which has a C-8 keto group rather than the C-8 ester of T-2 toxin.