Phenotypic and genetic variability of Pectobacterium carotovorum isolated from artichoke in the Sele valley.

Abstract

Phenotypic and genetic characteristics were investigated of 24 isolates of Pectobacterium carotovorum, recovered in summer 2001 from artichokes in the Sele valley (Campania, southern Italy). Based on biochemical tests, all isolates were identified as P. carotovorum subsp. carotovorum, except for four atypical ones. PCR-amplification of a 434 bp fragment of the pectate-lyase-encoding pel gene, gave the expected band from all isolates, whereas no amplicons were obtained using P. atrosepticum-specific primers. PCR-RFLP on pel gene, placed the four atypical isolates in the RFLP groups 8, 9 and 11 (ISPaVe 110A, ISPAVe 105A and ISPAVe 91B) of the subspecies carotovorum and in the RFLP group 3 of the subspecies odoriferum (ISPaVe CA). DNA-polymorphism investigated by rep-PCR and M13-PCR showed the isolates to be distributed in two main groups, totalling 14 haplotypes. Eight different haplotypes were obtained from samples collected in the same field and three different haplotypes were found in the same plant. The rep-PCR fingerprinting of ISPaVe CA was the same as P. carotovorum subsp. odoriferum NCPPB 3839. The majority of the isolates did not show a significative differential virulence response, with the exception of ISPaVe 114B, the most-virulent, and ISPaVe 105B, the least-virulent.