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Disruption of the GABA shunt affects mitochondrial respiration and virulence in the cereal pathogen F usarium graminearum
Author(s) -
Bönnighausen Jakob,
Gebhard Daniel,
Kröger Cathrin,
Hadeler Birgit,
Tumforde Thomas,
Lieberei Reinhard,
Bergemann Jörg,
Schäfer Wilhelm,
Bormann Jörg
Publication year - 2015
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.13203
Subject(s) - biology , biochemistry , pathogen , mitochondrion , mutant , virulence , citric acid cycle , metabolism , oxidative stress , microbiology and biotechnology , gene
Summary The cereal pathogen F usarium 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.