Saprotrophic proteomes of biotypes of the witches’ broom pathogen Moniliophthora perniciosa

Nine geographically diverse isolates of the witches’ broom pathogen Moniliophthora perniciosa were cultured on nutrient medium. They included six C-biotype strains (from five tropical American countries) differing in virulence on the cacao plant Theobroma cacao, two Brazilian S-biotypes, infective on solanaceous hosts, and an Ecuadorian L-biotype, infective on certain lianas. Mycelial growth rates and morphologies differed considerably between the strains, but no characters were observed to correlate with virulence or biotype. In plant inoculations using spores from basidiocarp-producing cultures, one C-biotype caused symptoms on tomato, an S biotype host. Mycelial proteomes of the nine strains were analyzed by two-dimensional gel electrophoresis (2-DE), and 619 gel spots were indexed on all replicate gels of at least one strain. Multivariate analysis of these gel spots discriminated the L-biotype, but not the S-biotypes, from the remaining strains. The proteomic similarity of the S and C-biotypes could be seen as consistent with the limited host adaptation seen in our plant infections. Sequences from tandem mass spectrometry of tryptic peptides from major 2-DE spots were matched with Moniliophthora genome and transcript sequences on the NCBI and Witches’ Broom Disease Transcriptome Atlas databases. The protein-spot identifications indicated the M. perniciosa saprotrophic mycelial proteome expressed functions potentially connected with a ‘virulence life-style’. These included peroxiredoxin, heat-shock proteins, nitrilase, formate dehydrogenase, a prominent complement of aldo-keto reductases, mannitol-1-phosphate dehydrogenase, and central metabolism enzymes with proposed pathogenesis functions.