The Grouping of Strains of Pseudomonas syringae subsp. savastanoi by DNA Restriction Fingerprinting

A selected group of strains of Pseudomonas syringae subsp. savastanoi from olive, oleander and ash were compared with pathogenicity tests and with DNA restriction fingerprinting using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and silver staining. The strains from each host were distinguishable by their pathogenicity to the same host and to the other two plant species. A division into the same groups was obtained with unweighted pair-group method with averages (UPGMA) clustering of the data from genomic fingerprinting, even though high overall similarity between the strains also indicated that they formed a single, well characterized taxon. It seems clear that the subspecies savastanoi of P. syringae comprises at least 3 groups of strains that differ in their precise host range, in the nature of the symptoms induced on the individual hosts, and in their genomic profile.