TACKLING HUMULUS LUPULUS FUNGAL DISEASES BY STUDYING A HOP CELL WALL / FUSARIUM GRAMINEARUM MODEL

The filamentous fungus Fusarium graminearum (teleomorph Gibberella zeae) was repeatedly isolated from diseased hop plants. The secreted proteome (exo-proteome) of an isolate grown on a hop cell wall medium revealed a highly diverse set of cell wall degrading enzymes (CWDE). Representing an important category of CWDE, xylanases were further subjected to bioinformatics analysis. 32 genes were predicted to code for xylanolytic enzymes in the fungal genome and 30 of them were confirmed to be expressed on the cell wall medium by qRT-PCR. The complete transcriptome was studied via whole genome DNA chips, resulting in the identification of all the genes required for the complete conversion of cell wall polysaccharides into monomers. The corresponding enzymatic activities were confirmed by Polysaccharide Analysis using Carbohydrate gel Electrophoresis (PACE) and cooperative activity of various identified CWDE was demonstrated by recombinant enzyme assays.