Plasmid Structure and Function in Plant-Pathogenic Pseudomonas Syringae (outer-Membrane Proteins)
Thirty isolates of Pseudomonas syringae pv/ tabaci, pv. angulata, (pathogens on tobacco) pv. coronafaciens, and pv. striafaciens (pathogens on oat) were examined for plasmid DNAs. The strains were obtained from plants throughout the world and some over 30 years ago. Sixteen of the twenty-two tobacco pathogens contain predominately one type of plasmid species, pJP27.00-type. The remaining six tobacco-specific strains do not harbor plasmids. The oat pathogens contain either one, two or three plasmids. DNA homology studies indicate, that the plasmid DNAs are highly conserved. More importantly, the plasmids harbored by strains isolated from one host plant are most stringently conserved. In fact, the plasmids from the tobacco pathogens are, with one exception, indistinguishable by restriction endonuclease digestions and Southern hybridization. There is also extensive homology among plasmids indigenous to the oat-specific Pseudomonas syringae pv. coronafiens and pv. striafaciens strains. However, some of the multiple plasmids within an individual strain are unrelated.
University of Illinois - Urbana-Champaign
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