Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: November 12, 1998
Publication Date: N/A
Technical Abstract: F. graminearum causes head scab of wheat and other small grains. This disease has resulted in economic losses to U.S. wheat and barley production measured in the billions of dollars over the last several years and is an important agricultural production and food safety problem worldwide. F. graminearum is also associated with ear and root rots on corn. Biosynthesis of trichothecenes from sesquiterpene precursors by several Fusarium species has been shown to involve many steps and many of these genes are located in a gene cluster. The gene TRI5 is responsible for the transformation of farnesyl pyrophosphate to trichodiene, the unoxygenated sesquiterpene precursor of trichothecenes. TRI5 has been cloned and was knocked out in F. graminearum to generate a strain that was no longer able to make any trichothecenes. When wheat in the field was inoculated with this strain, less disease and less yield loss was observed compared to wheat inoculated with the wild type progenitor strain that still made trichothecenes. These results demonstrate that ability to make trichothecenes is a virulence factor for the fungus on wheat. Fumonisins, produced by F. moniliforme, are frequently found in corn and corn products worldwide. Fumonisins are implicated as liver toxins in many species, cause equine leucoencephalomalacia, and porcine pulmonary edema. They have also been implicated as potential liver carcinogens in rats. Preliminary evidence has also suggested that fumonisins may be virulence factors for invasion of corn by F. moniliforme. Experiments testing this hypothesis will be presented and discussed.