The Role of Deoxynivalenol and 15-Acetyldeoxynivalenol in Pathogenesis byGibberella zeae,as Elucidated Through Protoplast Fusions Between Toxigenic and Nontoxigenic Strains

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Abstract
Deoxynivalenol (DON) and 15-acetyldeoxynivalenol (15-ADON) are trichothecene mycotoxins produced by Gibberella zeae, a pathogen of wheat, maize and carnation. Low levels of DNO inhibit protein synthesis in maize and wheat. We tested the possible role of DON and 15-ADON as virulence factors in inoculation experiments with regenerated products of protoplast fusion of auxotrophs of a toxigenic, pathogenic strain (type A) with auxotrophs of a nontoxigenic, nonpathogenic strain (type B). Nineteen independent fusion products and their parental strains were evaluated for toxin formation and pathogenicity on four cultivars of maize and one cultivar of carnation. Toxin production was analyzed by thin-layer chromatography of extracts from infected maize and rich grains and by axenic liquid cultures. Fourteen fusion products were nontoxic, but eight of these were highly virulent ear mold pathogens of maize and stub dieback pathogens of carnation. We conclude that DON and 15-ADON are not pathogenicity or virulence factors for G. zeae on maize of carnation.