Different genes of the ubiquitin-proteasome system regulate development and virulence in the cereal pathogen Fusarium graminearum

Gunnar Baermann 1 Michael Tatham 2 Ron Hay 2 Wilhelm Schäfer 1
1Molecular Plant Pathology, University of Hamburg, Hamburg, Germany
2Centre for Gene Regulation and Expression, University of Dundee, Dundee, UK

The ubiquitin-proteasome system (UPS) uses ubiquitin to mark proteins for rapid proteolysis and is a universal process in eukaryotes, including humans. Malfunctions in the UPS may result in severe diseases.

The fungal plant pathogen Fusarium graminearum is a major pathogen of cereals world-wide. During the initial infection on wheat flower leaves Fusarium graminearum forms two morphologically distinct structures, non-invasive runner hyphae and invasive compound appressoria. Transcriptome analyses of runner hyphae and infection cushions identified 158 genes most likely involved in the ubiquitin-proteasome system.

Disruption of two different F-box proteins and one ubiquitin-conjugating enzyme resulted in fungal mutants deficient in different aspects of development such as hyphal branching, sexual and vegetative propagation, and virulence.

A detailed proteomic analysis of the mutants identified changes in pathways relevant to the observed mutant phenotypes. Furthermore, motif analysis was done using all ubiquitin remnant peptides in an ubiquitin remnant motif antibody scan, followed by LC-MS/MS analysis. Proteins with altered ubiquitination will be presented and discussed in the context of the mutants phenotypes.