Author
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Desjardins, Anne |
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Submitted to: National Capital Area Tissue Culture Society
Publication Type: Abstract Only Publication Acceptance Date: 9/27/1995 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Biochemical interactions between plant-pathogenic fungi and higher plants are both complex and highly integrated. Genetic dissection of these complex interactions can be conducted by targeted gene disruption. Genetic analysis is particularly straightforward in many plant pathogenic fungi, such as Gibberella species, that have a haploid genome and are amenable to DNA-mediated transformation. Gibberella zeae is an important pathogen of cereal crops and produces trichothecene toxins which are injurious to human and animal health. Targeted gene disruption was used to determine the importance of trichothecenes in wheat head scab. Trichothecene nonproducing mutants were generated by transformation-mediated replacement of the gene (Tri5) that encodes the first enzyme in the trichothecene biosynthetic pathway. Under permit from USDA-APHIS, pathogenicity of a mutant with a Tri5 gene replacement and of its Tri5+ progenitor were examined under field conditions. Two wheat cultivars were grown in central Illinois and inoculated at anthesis by injecting individual heads with fungal conidia or with water. After one month, heads were harvested and seeds were analyzed for yield and quality, and for infection with wildtype strains and the Tri5- mutant by fungal strain isolation and PCR. The Tri5- mutant was able to infect wheat seeds, but was significantly less pathogenic (P<.05) then the Tri5+ progenitor on both wheat cultivars as measured by seed number, weight and germinability. These results indicate that trichothecenes contribute to the ability of G. zeae to cause wheat head scab under field conditions. |
