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 an d with DNA restriction fingerprinting using sodium dodecyl sulphate-po lyacrylamide gel electrophoresis (SDS-PAGE) and silver staining. The s trains from each host were distinguishable by their pathogenicity to t he same host and to the other two plant species. A division into the s ame groups was obtained with unweighted pair-group method with average s (UPGMA) clustering of the data from genomic fingerprinting, even tho ugh high overall similarity between the strains also indicated that th ey formed a single, well characterized taxon. It seems clear that the subspecies savastanoi of P. syringae comprises at least 3 groups of st rains that differ in their precise host range, in the nature of the sy mptoms induced on the individual hosts, and in their genomic profile.