title: Disruption of the GABA shunt affects mitochondrial respiration and virulence in the cereal pathogen Fusarium graminearum.
abstract: The cereal pathogen Fusarium graminearum threatens food and feed production worldwide. It reduces the yield and poisons the remaining kernels with mycotoxins, notably deoxynivalenol (DON). We analyzed the importance of gamma-aminobutanoic acid (GABA) metabolism for the life cycle of this fungal pathogen. GABA metabolism in F. graminearum is partially regulated by the global nitrogen regulator AreA. Genetic disruption of the GABA shunt by deletion of two GABA transaminases renders the pathogen unable to utilize the plant stress metabolites GABA and putrescine. The mutants showed increased sensitivity against oxidative stress, GABA accumulation in the mycelium, downregulation of two key enzymes of the TCA cycle, disturbed potential gradient in the mitochondrial membrane and lower mitochondrial oxygen consumption. In contrast, addition of GABA to the wild type resulted in its rapid turnover and increased mitochondrial steady state oxygen consumption. GABA concentrations are highly upregulated in infected wheat tissues. We conclude that GABA is metabolized by the pathogen during infection increasing its energy production, whereas the mutants accumulate GABA intracellularly resulting in decreased energy production. Consequently, the GABA mutants are strongly reduced in virulence but, because of their DON production, are able to cross the rachis node.
authors: Biocenter Klein Flottbek, Department of Molecular Phytopathology and Genetics, University of Hamburg, Ohnhorststr. 18, D-22609, Hamburg, Germany.
authors: Jakob
authors: J
authors: Bönnighausen
authors: Department of Life Sciences, Albstadt-Sigmaringen University of Applied Sciences, Anton-Günther-Str. 51, D-72488, Sigmaringen, Germany.
authors: Daniel
authors: D
authors: Gebhard
authors: Biocenter Klein Flottbek, Department of Molecular Phytopathology and Genetics, University of Hamburg, Ohnhorststr. 18, D-22609, Hamburg, Germany.
authors: Cathrin
authors: C
authors: Kröger
authors: Biocenter Klein Flottbek, Department of Molecular Phytopathology and Genetics, University of Hamburg, Ohnhorststr. 18, D-22609, Hamburg, Germany.
authors: Birgit
authors: B
authors: Hadeler
authors: Biocenter Klein Flottbek, Department of Applied Plant Ecology and Biodiversity of Useful Plants, University of Hamburg, Ohnhorststr. 18, D-22609, Hamburg, Germany.
authors: Thomas
authors: T
authors: Tumforde
authors: Biocenter Klein Flottbek, Department of Applied Plant Ecology and Biodiversity of Useful Plants, University of Hamburg, Ohnhorststr. 18, D-22609, Hamburg, Germany.
authors: Reinhard
authors: R
authors: Lieberei
authors: Department of Life Sciences, Albstadt-Sigmaringen University of Applied Sciences, Anton-Günther-Str. 51, D-72488, Sigmaringen, Germany.
authors: Jörg
authors: J
authors: Bergemann
authors: Biocenter Klein Flottbek, Department of Molecular Phytopathology and Genetics, University of Hamburg, Ohnhorststr. 18, D-22609, Hamburg, Germany.
authors: Wilhelm
authors: W
authors: Schäfer
authors: Biocenter Klein Flottbek, Department of Molecular Phytopathology and Genetics, University of Hamburg, Ohnhorststr. 18, D-22609, Hamburg, Germany.
authors: Jörg
authors: J
authors: Bormann
mesh_terms: D000612:4-Aminobutyrate Transaminase / Q000235:genetics / Q000378:metabolism; D004734:Energy Metabolism; D005670:Fusarium / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism* / Q000472:pathogenicity; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D009154:Mutation; D025282:Mycelium / Q000737:chemistry; D009183:Mycotoxins / Q000096:biosynthesis; D018384:Oxidative Stress; D010101:Oxygen Consumption; D011700:Putrescine / Q000378:metabolism; D014255:Trichothecenes / Q000096:biosynthesis / Q000378:metabolism; D014908:Triticum / Q000382:microbiology*; D014774:Virulence / Q000235:genetics; D005680:gamma-Aminobutyric Acid / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D009183:Mycotoxins; D014255:Trichothecenes; D005680:gamma-Aminobutyric Acid; D000612:4-Aminobutyrate Transaminase; C007262:deoxynivalenol; D011700:Putrescine