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Specific Detection of Erwinia carotovora subsp. atroseptica with a Digoxigenin-labeled DNA Probe. L. J. Ward, Agriculture Canada, Vancouver Research Station, Vancouver, BC V6T 1X2; S. H. De Boer, Agriculture Canada, Vancouver Research Station, Vancouver, BC V6T 1X2. Phytopathology 84:180-186. Accepted for publication 17 November 1993. Copyright 1994 Department of Agriculture, Government of Canada. DOI: 10.1094/Phyto-84-180.

A DNA probe specific for all four serogroups of Erwinia carotovora subsp. atroseptica was selected from an EcoRI digest of a cloned library constructed with the combined genomic DNA from strains 6, 31, 196, and 198, which each represented one of the serogroups of E. c. atroseptica. Specificity of the probe was initially tested against a panel of 40 E. carotovora strains representing serogroups I through XL. Subsequently hybridization of the probe, labeled with digoxigenin, was tested against an additional 82 strains of E. carotovora. The probe hybridized to all strains previously identified as E. c. atroseptica on the basis of biochemical and physiological tests, and it hybridized weakly with only one strain that was not a typical E. c. atroseptica strain. This strain had been isolated from cauliflower in the United Kingdom. The probe hybridized with partially purified DNA extracted from enrichments of potato periderm to which as few as 10 colony-forming units per milliliter were added prior to incubation for 48 h. The hybridization reactions to enrichment preparations were quantified by reading gray values from video images of the chemilumograms.