Submitted to: Fungal Genetics and Biology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/3/2011
Publication Date: 3/9/2011
Citation: Alexander, N.J., McCormick, S.P., Waalwijk, C., Van Der Lee, T., Proctor, R. 2011. The genetic basis for 3-ADON and 15-ADON trichothecene chemotypes in Fusarium graminearum. Fungal Genetics and Biology. 48(5):485-495. Interpretive Summary: In this research, we identified genetic changes that determine the type of mycotoxin that is produced by the fungus Fusarium. Fusarium head blight, a serious disease of cereal crops, has severe economic and health impacts due to the presence of mycotoxins made by the invading mold. In the U.S., the predominant Fusarium species produces the mycotoxin 15-acetyldeoxynivalenol (15-ADON), however, recent surveys suggest that new lines of Fusarium which produce the mycotoxin 3-acetyldeoxynivalenol are emerging. The present research found that changes in a single mycotoxin biosynthetic gene determined if 15-ADON or 3-ADON was produced by a strain of Fusarium. This research provides the basis for risk assessment studies on the aggressiveness of each chemotype in causing disease on wheat.
Technical Abstract: Fusarium graminearum isolates typically produce trichothecene mycotoxins as secondary metabolites. These can be classified into three chemotypes: 3-acetyldeoxynivalenol (3-ADON) producers, 15-acetyldeoxynivalenol (15-ADON) producers, and nivalenol (NIV) producers. Here we report the genetic basis for the production of either 3-ADON or 15-ADON by selected strains of F. graminearum and other species. TRI3, which encodes a C-15 acetyltransferase, was found to be functional in all three chemotypes. Gene and protein sequence differences were found between TRI8 from 3-ADON chemotype strains and TRI8 from 15-ADON chemotype strains. Functional analyses, including gene disruption, cell-free feeding, yeast expression, and fungal transgenic expression, showed that the TRI8 from a 3-ADON producer encodes a C-15 trichothecene esterase while the TRI8 from a 15-ADON producer or a NIV producer encodes a C-3 trichothecene esterase.