Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 16, 2000
Publication Date: N/A
Technical Abstract: Fumonisins are polyketide mycotoxins produced by Gibberella fujikuroi mating population A (Fusarium verticillioides, synonym F. moniliforme), a major pathogen of maize worldwide. Fumonisins are associated with a number of mycotoxicoses, including leucoencephalomalacia in horses, pulmonary edema in swine, and liver cancer in rats. Fumonisins are structurally related to sphinganine, a sphingolipid biosynthetic intermediate, and to AAL toxin, a host-specific toxin produced by strains of Alternaria alternata. Both fumonisins and AAL toxin inhibit sphingolipid biosynthesis in plants and in animals, and both are phytotoxic to maize and tomato seedlings. Most wild-type strains produce high levels of fumonisin B1 (FB1), and low levels of FB2 and FB3 which are less oxygenated than FB1. Mutants that produce only FB2 or FB3 and mutants that produce no fumonisins have been identified in surveys of field strains or generated by UV mutagenesis or by targeted disruption of the FUM5 gene, which encodes a polyketide synthase essential for fumonisin biosynthesis. To test the role of fumonisins in pathogenesis on maize under field conditions, fumonisin B1-nonproducing mutants have been inoculated on maize ears and stalks and on seeds at planting. All results to date indicate that fumonisin production is not required for G. fujikuroi mating population A to cause maize ear rot or systemic infection.