Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: August 29, 1997
Publication Date: N/A
Technical Abstract: Mycotoxins are toxic fungal metabolites found in agricultural products that are characterized by their ability to cause health problems for vertebrates. Biosynthesis of trichothecenes is complex and at least ten pathway genes have been identified within a gene cluster spanning a 23 Kb region of DNA in F. sporotrichioides. Recent investigations of the trichothecene pathway gene cluster have provided new information concerning the transcriptional regulation of pathway gene expression (TRI6) and the transport of pathway products (TRI12). TRI6 binding occurs within the promoter regions of nine pathway genes and requires the presence of a seven nucleotide sequence (TNAGGCC). TRI12 encodes an apparent trichothecene transporter with structural similarities to members of the major facilitator superfamily of transporters. Disruption of TRI12 results in greatly reduced levels of trichothecene production. These and others results support the involvement of TRI12 in trichothecene transport. TRIr has been identified as a trichothecene resistance gene in F. sporotrichioides based on its ability to protect trichothecene-sensitive yeast strains. TRIr does not appear to be located in the pathway gene cluster and encodes a 3-O-acetyltransferase. Data base comparisons indicate TRIr encodes a protein that is most closely related (45% identity) to the product of a yeast ORF of unknown function. Expression of TRIr or other microbial trichothecene resistance genes in wheat may provide a means for confirming the importance of trichothecenes in Fusarium WHS.