Project description:Phytopathogenic Rathayibacter species are unique bacterial plant pathogens as they are obligately vectored by plant parasitic Anguinid nematodes to the developing seedheads of forage grasses and cereals. This understudied group of plant associated Actinomycetes includes the neurotoxigenic Plant Pathogen Select Agent, R. toxicus, which causes annual ryegrass toxicity in grazing livestock. The complexRathayibacter disease cycle requires intimate interactions with the nematode cuticle and plant hosts, which warrants an increased understanding of the secretory and surface-associated proteins that mediate these diverse eukaryotic interactions. Here we present the first comparative secretome analysis for this complex, nematode vectoredRathayibacter genera that compares three agronomically damaging Rathayibacterspecies, R. toxicus, R. iranicus, and R. tritici. The exoproteomic comparison identified 1,423 unique proteins between the three species using LC-MS/MS. Of the uniquely identified proteins, 94 homologous proteins were conserved between the three Rathayibacter exoproteomes and comprised between 43.4 to 58.6% of total protein abundance. Comparative analyses revealed both conserved and uniquely expressed extracellular proteins, which, interestingly, had more similarities to extracellular proteins commonly associated with bacterial animal pathogens than classical plant pathogens. This comparative exoproteome analysis will facilitate the characterization of proteins essential for vector and host colonization and assist in the development of diagnostic targets.
Project description:Rathayibacter toxicus is a gram-positive bacterium that is the causative agent of annual ryegrass toxicity, a disease that causes devastating losses in the Australian livestock industry. This bacterium is poorly characterized, making it difficult to accurately detect in feed samples. Using 1-D gels and mass spectrometry, we analyzed the protein expression of R. toxicus under stationary growth phase conditions to obtain a more complete understanding of the mechanisms of this organism. A total of 333 unique proteins were identified. The data obtained in this analysis is an essential first step toward developing an antibody-based diagnostic assay.