Genetic Analysis of Fumonisin Production and Virulence of Gibberella fujikuroi Mating Population A (Fusarium n10nilifolme) on Maize

The phytopathogenic fungus Gibberella jujikuroi mating population A (anamorph, Fusarium mOlliliforme) produces fumonisins, which are toxic to a wide range of plant and animal species. Previous studies of field strains have identified a genetic locus, designatedjiulll, that can determine whether fumonisins are produced. To test the relationship between fumonisin production and virulence on maize seedlings, a cross between a ji1l111+ field strain that had a high degree of virulence and a ji1l111field strain that had a low degree of virulence was made, and ascospore progeny were scored for these traits. Although a range of virulence levels was recovered among the progeny, high levels of virulence were associated with production of fumonisins, and highly virulent, fumonisin-nonproducing progeny were not obtained. A survey of field strains did identify a rare fumonisin-nonproducing strain that was quite high in virulence. Also, the addition of purified fumonisin BI to virulence assays did not replicate all of the seedling blight symptoms obtained \lith autoclaved culture material containing fumonisin. These results support the hypothesis that fumonisin plays a role in virulence but also indicate that fumonisin production is not necessary or sufficient for virulence on maize seedlings.