An Indigenous Virulent Strain of Erwinia amylovora Lacking the Ubiquitous Plasmid pEA29.

ABSTRACT An atypical strain of Erwinia amylovora was isolated near an outbreak of fire blight at a nursery in Spain in 1996. It was obtained from a Crataegus plant showing typical symptoms and was identified as E. amy-lovora by biochemical tests and enrichment-enzyme-linked immuno-sorbent assay, but not by polymerase chain reaction using primers based on the pEA29 sequence.

Following spread of fire blight in Western, Central and Southern Europe by molecular differentiation of Erwinia amylovora strains with PFGE analysis.

Fire blight has been detected recently in several areas of northern Spain and north-eastern Italy. To follow spread of the disease within Europe, more than 120 Erwinia amylovora strains isolated from 1957-1900 in England, France, Germany, The Netherlands, Belgium, Poland, Italy and Spain were assayed using pulsed-field gel electrophoresis (PFGE) analysis of genomic DNA after XbaI digestion. Pattern types Pt1 and Pt4 were found for strains from England.