Erwinia pyrifoliae sp. nov., a novel pathogen that affects Asian pear trees (Pyrus pyrifolia Nakai).
A novel pathogen from Asian pears (P. pyrifolia) was analysed by sequencing the 16S rDNA and the adjacent intergenic region, and the data were compared to related Enterobacteriaceae. The 16S rDNA of the Asian pear pathogen was almost identical with the sequence of Erwinia amylovora, in contrast to the 16S-23S rRNA intergenic transcribed spacer region of both species. A dendrogram was deduced from determined sequences of the spacer regions including those of several related species such as Erwinia amylovora, Enterobacter pyrinus, Pantoea stewartii subsp. stewartii and Escherichia coli. Dendrograms derived from 121 biochemical characteristics including Biotype 100 data placed the Asian pear pathogen close to Erwinia amylovora and more distantly to other members of Erwinia. Another DNA relatedness study was performed by DNA hybridizations and estimation of ΔTm values. The Asian pear strains constituted a tight DNA hybridization group (89-100%) and were barely related to strains of Erwinia amylovora (40-50%) with a ΔTm in the range of 5.2-6.8. The G+C content of DNA from the novel pathogen was 52 mol%. It is suggested that strains isolated from Asian pears constitute a new species and the name Erwinia pyrifoliae sp. nov. is proposed. The type strain is strain Ep16/96T (= CFBP 4172T = DSM 12163T).