ARS | Publication request: Variability in mycotoxin biosynthetic genes in Fusarium and its effect on mycotoxin contamination of crops

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: September 10, 2011
Publication Date: September 10, 2011
Citation: Proctor, R., Mccormick, S.P., Alexander, N.J., Busman, M., Ward, T.J. 2011. Variability in mycotoxin biosynthetic genes in Fusarium and its effect on mycotoxin contamination of crops. Meeting Abstract.

Technical Abstract: The Fusarium metabolites fumonisins and trichothecenes are among the mycotoxins of greatest concern to food and feed safety worldwide. As is the case for other fungal secondary metabolite biosynthetic genes, mycotoxin biosynthetic genes are often located adjacent to one another in gene clusters. Thus, fumonisin biosynthetic genes (FUMs) are located in a 16-gene FUM cluster, and most trichothecene biosynthetic genes (TRIs) are located in a 10 to 14-gene TRI cluster. In fumonisin-producing fusaria, the FUM cluster is uniform in gene order and orientation, but the genomic location of the cluster can differ among species; cluster location is the same in closely related species but different in more distantly related species. In fumonisin-nonproducing fusaria, lack of production can result from: 1) a point mutation within a critical FUM cluster gene; 2) loss of a key gene from the FUM cluster; or 3) absence of the entire cluster. In contrast to the FUM cluster, the TRI cluster exhibits variation in gene organization among trichothecene-producing fusaria. However, variation in TRI gene sequences rather than gene organization contributes to variability in trichothecene production. For example, variability in sequence of the gene TRI1 can contribute to whether fusaria produce the 8-keto trichothecenes nivalenol and deoxynivalenol (DON) versus T-2 toxin, a trichothecene that lacks an 8-keto function. Likewise, variability in the gene TRI8 can determine whether Fusarium produces either 3-acetyl DON or 15-acetyl DON. Thus, variability in mycotoxin biosynthetic genes in Fusarium can affect structural diversity of the mycotoxins produced as well as mycotoxin production versus nonproduction. Such variability can in turn affect mycotoxin contamination of food and feed crops.fusaria, variation in TRI gene sequences can give rise to variability in trichothecene structures. Sequence variability in the TRI1 gene can contribute to whether fusaria produce nivalenol and deoxynivalenol (DON), trichothecenes with an 8-keto function, or T-2 toxin, a trichothecene that lacks an 8-keto function. Likewise, variability in TRI8 can determine whether Fusarium produces either 3-acetyl DON or 15-acetyl DON. Thus, variability in mycotoxin biosynthetic genes in Fusarium can affect structural diversity of mycotoxin as well as production versus nonproduction, and these differences can affect mycotoxin contamination of food and feed crops.