Identification of Erwinia amylovora, the Fireblight Pathogen, by Colony Hybridization with DNA from Plasmid pEA29

Abstract

All strains of Erwinia amylovora characterized carry a medium-size plasmid of 29 kilobases (pEA29). We mapped this plasmid with various restriction enzymes, cloned the whole DNA into an Escherichia coli plasmid, and subcloned restriction fragments. These DNA species were used for identification of E. amylovora after handling of strains in the laboratory and also in field isolates. About 70 strains of E. amylovora and 24 strains from nine other species, mainly found in plant habitats, were checked in a colony hybridization test. Virulent and avirulent E. amylovora strains reacted positively, whereas the other species were negative. Apart from the hybridization assay, the positive strains were additionally tested for ooze production on rich agar with 5% sucrose and on immature-pear slices. Unspecific background hybridization of nonE. amylovora strains found for hybridization with the whole E. amylovora plasmid was almost eliminated when a 5-kilobase Sail fragment from pEA29 was used as a probe and when the washes after the hybridization procedure were done with high stringency. Under these conditions, E. amylovora could be readily identified from field isolates.

Transgenic expression of a viral EPS‐depolymerase is potentially useful to induce fire blight resistance in apple

“…This strain was isolated in Germany from Cotoneaster spp. in 1979 (Falkenstein et al , 1988). Strains Ea512 and Ea514 were isolated by Dr E. Moltmann (Landesanstalt für Pflanzenschutz, Stuttgart, Germany) from Cydonia and Malus , respectively.…”

Survival Studies with the Fire Blight Pathogen Erwinia amylovora in Soil and in a Soil‐inhabiting Insect

“…Agrobacterium tumefaciens strain C58 was obtained from M. van Montague, Ghent, and used to create strain C58SR (Sm R , Rif R ). Erwinia amylovora strain Ea1/79 was used as wild type (Falkenstein et al., 1988), expressing kanamycin‐resistance of plasmid pfdC1Z′‐gfp. Erwinia herbicola (synonymous Pantoea agglomerans ) strain EhNZ was isolated from pears (Bereswill et al., 1998) and was labelled with pfdC4Z′‐gfp, carrying chloramphenicol‐resistance, by electroporation.…”

Characterization of Bacillus strains from apple and pear trees in South Africa antagonistic to Erwinia amylovora

“…Ea1/79 was isolated in Germany from Cotoneaster sp. in 1979 [13], and a spontaneous streptomycin-resistant mutant was selected (Ea1/79Sm). Ea7/74-LS6, a levan-de-¢cient kanamycin-resistant mutant with reduced virulence, was created by transposon Tn5 mutagenesis [14].…”