GENOMIC FINGERPRINTING OF SOME PSEUDOMONAS SYRINGAE PV PISI STRAINS FROM SICILY
G. Cirvilleri, V. Catara, G. Caldarera , P. Caruso
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.