Detection and host range of Erwinia pyrifoliae
Erwinia pyrifoliae (EPPO Alert List) was recently described as a new pathogen of Asian pear (Pyrus pyrifolia) in Korea. It was isolated during 4 consecutive years (from 1995 to 1998) in Korea orchards, in the region of Chuncheon (south of the country), exclusively from necrotic Asian pear trees. The occurrence of this disease in other regions of Korea has not been reported. It can also be recalled that E. amylovora does not occurs in Korea. Although E. pyrifoliae resembles E. amylovora (symptoms on immature pear, colony morphology on certain growing medium), it differs from it in microbiological and molecular assays. A pair of specific PCR primers has been developed to detect E. pyrifoliae, but not Escherichia coli, Enterobacter pyrinus, Pantoea stewartii, Pseudomonas syringae, Xanthomonas campestris, E. amylovora, E. herbicola and several other Erwinia species. Using these primers, E. pyrifoliae was detected from necrotic pear leaves. The genome of several strains of E. pyrifoliae was digested by two restriction enzymes and DNA fragments were analysed (pulsed-field gel electrophoresis). The patterns obtained differed from those of E. amylovora, and showed some variability within E. pyrifoliae. In addition, the host range of E. pyrifoliae was studied. Several fireblight hosts (Cotoneaster, Crataegus, Malus domestica, Prunus salicifolia, Pyrus communis, Rubus idaeus, Pyrus pyrifolia) were inoculated with strains of E. pyrifoliae and E. amylovora. Results showed that leaf necrosis was only obtained with E. pyrifoliae on European and Asian pears. Some weak symptoms were observed on M. domestica (cv. Idared only). The authors noted that in 1999 and 2000, they have not been able to detect again E. pyrifoliae in the region where it was first found. Phytosanitary measures (no details given) were taken in affected orchards, and have apparently been successful in reducing or eliminating the pathogen. It is also noted that the specific primers for E. pyrifoliae can also detect some Erwinia strains from Japan (but not all of them).
Kim, W.S.; Jock, S.; Paulin, J.P.; Rhim, S.L.; Geider, K. (2001) Molecular detection of differentiation of Erwinia pyrifoliae and host range analysis of the Asian pear pathogen.
Plant Disease, 85(11), 1183-1188.