Genetic studies of Erwinia amylovora strains isolated from fruit trees and Rubus spp.
As mentioned in the EPPO RS 95/056, Erwinia amylovora (EPPO A2 quarantine pest) has been isolated from diseased Rubus in USA (Illinois, Maine, North Carolina, Ohio, Wisconsin). It appeared that strains of the bacterium isolated from Rubus can only infect Rubus, and that strains from other rosaceous plants are not pathogenic to Rubus. However, some doubts have been expressed as the pathogen has not been reported elsewhere on this genus. Nevertheless, genetic studies have been carried out in United States on 189 strains of E. amylovora isolated from different hosts (fruit trees and Rubus), from North America and New Zealand. Two polymerase chain reaction (PCR)-based techniques have been used. Results showed that strains of E. amylovora isolated from fruit trees are genetically homogeneous (strains from Rubus are more heterogeneous) and can be distinguished from strains isolated from Rubus species. The authors felt that these results corroborate previous conclusions based on pathogenicity tests that E. amylovora consists of at least two distinct subgroups.
Sources
McManus, P.S.; Jones, A.L. (1995) Genetic fingerprinting of Erwinia amylovora strains isolated from tree-fruit crops and Rubus spp.
Phytopathology, 85(12), 1547-1553.