title: Characterising the role of GABA and its metabolism in the wheat pathogen Stagonospora nodorum.
abstract: A reverse genetics approach was used to investigate the role of γ-aminobutyric acid metabolism in the wheat pathogenic fungus Stagonospora nodorum. The creation of mutants lacking Sdh1, the gene encoding succinic semialdehyde dehydrogenase, resulted in strains that grew poorly on γ-aminobutyric acid as a nitrogen source. The sdh1 mutants were more susceptible to reactive oxygen stress but were less affected by increased growth temperatures. Pathogenicity assays revealed that the metabolism of γ-aminobutyric acid is required for complete pathogenicity. Growth assays of the wild-type and mutant strains showed that the inclusion of γ-aminobutyric acid as a supplement in minimal media (i.e., not as a nitrogen or carbon source) resulted in restricted growth but increased sporulation. The addition of glutamate, the precursor to GABA, had no effect on either growth or sporulation. The γ-aminobutyric acid effect on sporulation was found to be dose dependent and not restricted to Stagonospora nodorum with a similar effect observed in the dothideomycete Botryosphaeria sp. The positive effect on sporulation was assayed using isomers of γ-aminobutyric acid and other metabolites known to influence asexual development in Stagonospora nodorum but no effect was observed. These data demonstrate that γ-aminobutyric acid plays an important role in Stagonospora nodorum in responding to environmental stresses while also having a positive effect on asexual development.
authors.affiliation: Plant Sciences Division, Research School of Biology, The Australian National University, Canberra, Australia.
authors.forename: Oliver
authors.initials: O
authors.lastname: Mead
authors.forename: Eli
authors.initials: E
authors.lastname: Thynne
authors.forename: Britta
authors.initials: B
authors.lastname: Winterberg
authors.forename: Peter S
authors.initials: PS
authors.lastname: Solomon
mesh_terms: D001203:Ascomycota / Q000201:enzymology / Q000378:metabolism* / Q000502:physiology; D004789:Enzyme Activation; D013172:Spores, Fungal / Q000502:physiology; D050644:Succinate-Semialdehyde Dehydrogenase / Q000172:deficiency / Q000378:metabolism; D014908:Triticum / Q000382:microbiology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D005680:gamma-Aminobutyric Acid; D050644:Succinate-Semialdehyde Dehydrogenase