Submitted to: Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/27/2000
Publication Date: N/A
Citation: Interpretive Summary: Gibberella zeae causes wheat ear blight and also contaminates grain with the toxin deoxynivalenol. In this study, we conducted genetic analysis of the fungus and tested its virulence on wheat ears in the greenhouse. Our results show that the ability to produce deoxynivalenol increases the ability of this fungus to cause wheat ear blight. This information should help wheat breeders develop cultivars that are resistant to ear blight.
Technical Abstract: Gibberella zeae causes wheat ear blight and produces trichothecene toxins in infected grain. In previous studies, trichothecene production in this fungus was disabled by specific disruption of the trichodiene synthase gene (Tri5) and was restored by two methods: gene reversion and transformation-mediated mutant complementation. In previous field tests of wheat ear blight, trichothecene-nonproducing mutants were less virulent than the wild-type progenitor strain from which they were derived. Trichothecene-producing revertants also were restored to wild-type levels of virulence. In contrast, in the field test of wheat ear blight reported here, trichothecene-producing mutants obtained by Tri5 complementation were not restored to wild-type levels of virulence. The complemented mutants showed a slightly reduced radial growth compared to the wild-type strain, but otherwise appeared normal in morphology, pigmentation, and sexual fertility. Genetic analysis indicated that the aberrant virulence of a complemented mutant was likely due to non-target effects that occurred during the process of transforming the trichothecene-nonproducing mutant with Tri5. These results confirm our previous findings that trichothecenes contribute to the virulence of G. zeae and also demonstrate that manipulating this fungus in the laboratory may cause it to undergo subtle changes that reduce its virulence.