Submitted to: Aflatoxin Workshop
Publication Type: Abstract Only
Publication Acceptance Date: October 27, 2000
Publication Date: N/A
Technical Abstract: Fumonisins are a family of toxic fungal metabolites produced by Fusarium verticillioides, a fungus frequently found in corn worldwide. Fumonisins can be found at detectable levels in most samples of corn worldwide, but the level is generally low in high quality corn. Much higher levels can be found in visibly diseased and lower quality corn. The most effective control strategy to minimize fumonisin contamination in corn would be prevention of Fusarium infection and fumonisin production in the field and in storage. However, because of the close association of the fungus and corn, and because most isolates of F. verticillioides have the potential to produce high levels of fumonisins at the present time, this is not practical. We observed that although F. verticillioides can be isolated from most of the kernels, even in highly contaminated corn, the overwhelming majority of the fumonisins (>90%) are found in damaged, visually infected and abnormal kernels while the visually healthy kernels contain only traces of fumonisins. In 1999, we conducted a field test to rigorously test the role in infection and ear rot disease for a single gene (FUM5) that confers F. verticillioides the ability to produce fumonisins at two sites. Five blocks of 10 plants were treated each of four ways; by toothpick treatment, by stalk inoculation, by spraying emerging silks, by silk channel inoculation and water controls. Fumonisin levels in ears inoculated via silk channel with the two FUM5- knockout were significantly lower than those in control which were significantly lower than those from plants inoculated with fumonisin producing non transgenic strains.