Genomic fingerprinting of some Pseudomonas syringae pv. pisi strains from Sicily

Pseudomonas syringae pv. pisi strains were characterized by pathogenicity tests on eight differential pea genotypes and by two genomic fingerprinting methods: PCR with REP and ERIC primers, and pulsed-field gel electrophoresis (PFGE) of genomic DNA digested by rare-cutting restriction endonucleases. The study comprised reference type strains of all 7 known races and 21 strains obtained from field pea crops in Sicily. PFGE was the most discriminatory method, delineating 6 pulsed-field gel profiles not coinciding with races, whereas REP and ERIC PCR identified 2 profile types. All the P. syringae pv. pisi isolated in Sicily were identified as race 6 on the basis of pathogenicity tests, and their genomic fingerprints by PFGE and REP and ERIC PCR were identical and more closely related to the type strains of races 3 and 6 than to those of the other races. The results are discussed in relation to improvement of detection methods and race-identification protocols.