Erwinia pyrifoliae sp. nov., a novel pathogen that affects Asian pear trees (Pyrus pyrifolia Nakai)

A novel pathogen from Asian pears (Pyrus pyrifolia Nakai) was analysed by s equencing the 16S rDNA and the adjacent intergenic region, and the data wer e compared to related Enterobacteriaceae. The 16S rDNA of the Asian pear pa thogen was almost identical with the sequence of Erwinia amylovora, in cont rast to the 16S-23S rRNA intergenic transcribed spacer region of both speci es. A dendrogram was deduced from determined sequences of the spacer region s including those of several related species such as Erwinia amylovora, Ent erobacter 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 mor e distantly to other members of the species Erwinia and to the species Pant oea and Enterobacter, Another DNA relatedness study was performed by DNA hy bridizations and estimation of Delta T-m values. The Asian pear strains con stituted a tight DNA hybridization group (89-100 %) and were barely related to strains of Erwinia amylovora (40-50 %) with a Delta T-m in the range of 5.2-6.8. The G+C content of DNA from the novel pathogen is 52 mol%, Theref ore, it is proposed that strains isolated from Asian pears constitute a new species and the name Erwinia pyrifoliae is suggested; the type strain is s train Ep16/96(T) (= CFBP 4172(T) = DSM 12163(T)).