ARS | Publication request: Variability in mycotoxin biosynthetic genes and gene clusters in Fusarium and its implications for mycotoxin contamination of crops

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 6, 2011
Publication Date: April 6, 2011
Citation: Proctor, R. 2011. Variability in mycotoxin biosynthetic genes and gene clusters in Fusarium and its implications for 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 with other fungal secondary metabolites, mycotoxin biosynthetic genes are often located adjacent to one another in gene clusters. Thus, fumonisin biosynthetic genes (FUMs) are located adjacent to one another in a 16-gene FUM cluster. In some species, trichothecene biosynthetic genes (TRIs) are distributed among three loci: a 12-gene TRI cluster, a two-gene TRI1-TRI16 locus, and a single-gene TRI101 locus. In other species, however, the TRI1 and TRI101 genes are located in the cluster and only TRI16 is at another location. In fumonisin-producing fusaria, the FUM gene 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 isolates and lineages of species that normally produce the toxins, lack of production can be caused by: 1) a point mutation within a key FUM cluster gene; 2) loss of a key gene from the FUM cluster; or 3) absence of the entire cluster. Among trichothecene-producing fusaria, variability in TRI genes can give rise to differences in trichothecene structure. Thus, DNA sequence variability in the TRI1 gene results in variation in function, which in turn contributes to whether fusaria produce either 8-keto trichothecenes (e.g. nivalenol or deoxynivalenol) or other trichothecenes that lack an 8-keto function (e.g. T-2 toxin). 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 production versus nonproduction and structural variability of mycotoxins, factors that can profoundly affect mycotoxin contamination of crops used for food and feed.