Submitted to: Fungal Genetics and Biology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/8/2003
Publication Date: 1/5/2004
Citation: Brown, D.W., Dyer, R.B., Mc Cormick, S.P., Kendra, D.F., Plattner, R.D. 2004. Functional demarcation of the fusarium core trichothecene gene cluster. Fungal Genetics and Biology. 41:454-462. Interpretive Summary: Fusarium species can often be found causing disease on corn and wheat in the field and may produce a variety of trichothecene mycotoxins which wind up contaminating human and animal feeds. Trichothecenes are potent inhibitors of protein synthesis and thus are an agricultural problem due to their harmful affect on human and animal health. One of the main goals of our group is to study genes involved in the synthesis of trichothecenes in order to identify possible targets for reducing or eliminating fungal infection and trichothecene contamination in wheat and corn. In this study, we examined 6 genes (spanning 10 kb of sequence) located adjacent to a cluster of 12 genes (spanning 22 kb) and determined that they are not required for trichothecene biosynthesis, despite the fact that two of the predicted proteins share similarity with enzymes whose activities are consistent with some unassigned steps in the trichothecene biosynthetic pathway. This research will benefit corn and grain producers and processors by providing additional potential targets to control trichothecene biosynthesis.
Technical Abstract: Fusarium species produce a variety of toxic sesquiterpenoid trichothecenes including T-2 toxin, deoxynivalenol (DON) and nivalenol (NIV). These toxins are potent inhibitors of protein synthesis and are a significant agricultural problem due to their detrimental affect on human and animal health. For some Fusarium species, trichothecenes are a critical component of virulence on certain crop plants. Almost all of the genes described involved in trichothecene biosynthesis in Fusarium sporotrichioides and F. graminearum are located in a cluster comprised of 12 open reading frames (ORFs). At present, the biochemical pathway leading from farnesyl pyrophosphate to T-2 toxin in F. sporotrichioides includes 15 steps. The core cluster, so far characterized account for 7 of these steps, with other, non-linked genes, TRI101 and TRI1, accounting for 2 other steps. This study examines nucleotide sequence downstream from the core cluster from both Fusarium in an effort to discover additional genes that may account for uncharacterized steps in the pathway. Sequence analysis, gene expression and gene disruption studies described here demarcate one end of the trichothecene gene cluster.