Relatedness of Chromosomal and Plasmid DNAs of Erwinia pyrifoliae and Erwinia amylovora

Abstract

The plant pathogen Erwinia pyrifoliae has been classified as a separate species from Erwinia amylovora based in part on differences in molecular properties. In this study, these and other molecular properties were examined for E. pyrifoliae and for additional strains of E. amylovora, including strains from brambles (Rubus spp.). The nucleotide composition of the internal transcribed spacer (ITS) region was determined for six of the seven 16S-23S rRNA operons detected in these species with a 16S rRNA gene probe. Each species contained four operons with a tRNA Glu gene and two with tRNA Ile and tRNA Ala genes, and analysis of the operons from five strains of E. amylovora indicated a high degree of ITS variability among them. One tRNA Glu -containing operon from E. pyrifoliae Ep1/96 was identical to one in E. amylovora Ea110, but three tRNA Glu operons and two tRNA Ile and tRNA Ala operons from E. pyrifoliae contained unique nucleotide changes. When groEL sequences were used for species-specific identification, E. pyrifoliae and E. amylovora were the closest phylogenetic relatives among a set of 12 bacterial species. The placement of E. pyrifoliae distinct from E. amylovora corroborated molecular hybridization data indicating low DNA-DNA similarity between them. Determination of the nucleotide sequence of plasmid pEP36 from E. pyrifoliae Ep1/96 revealed a number of presumptive genes that matched genes previously found in pEA29 from E. amylovora and similar organization for the genes and origins of replication. Also, pEP36 and pEA29 were incompatible with clones containing the reciprocal origin regions. Finally, the ColE1-like plasmid pEP2.6 from strain Ep1/96 contained sequences found in small plasmids in E. amylovora strains IL-5 and IH3-1.There are two subgroups of the fire blight pathogen Erwinia amylovora based on host range: one is able to cause disease on apple, pear, and related fruits, and the other is able to cause disease on raspberry, blackberry, and other bramble (Rubus) species. Although these organisms exhibit host specificity, they are considered identical species because DNA-DNA homology was high between the two subgroups (10). A bacterium isolated in Korea causes a shoot blight resembling symptoms of fire blight in shoots of Asian pear (23) and recently was designated a separate species, Erwinia pyrifoliae (21). It was differentiated from E. amylovora based on low relatedness (40 to 45%) in DNA-DNA similarity experiments; sequence divergence in the 16S-23S rRNA intergenic transcribed spacer (ITS) regions (21); and the number and size of bands in restriction studies of its plasmids (35).The taxonomic placement of E. pyrifoliae strain Ep1/96 within the genus Erwinia was based on high 16S rRNA gene sequence identity to several species in the genus, including E. amylovora. Strain Ep1/96 was classified as a new species, E. pyrifoliae, in part because of its phylogenetic distance from E. amylovora strain Ea1/79 when sequences for single operons of the 16S-23S rRNA ITS region from the two bacteria were co...

Genome Sequence of an Erwinia amylovora Strain with Pathogenicity Restricted to Rubus Plants

“…Genomic sequence comparison using EDGAR (1) revealed approximately 373 singletons from ATCC BAA-2158 that were absent or highly divergent in the genomes of Spiraeoideaeinfecting strains CFPB 1430 and ATCC 49946 of E. amylovora (10,12). However, genomic sequence comparison of ATCC BAA-2158 with these strains of E. amylovora and the closely related species E. pyrifoliae DSM 12163 T (11), E. tasmaniensis Et1/99 (5), and E. billingiae Eb661 (4) corroborates other analyses (e.g., DNA-DNA hybridization and sequencing of housekeeping genes) that retain ATCC BAA-2158 within the species E. amylovora (3,7).…”

The Omptins ofYersinia pestisandSalmonella entericaCleave the Reactive Center Loop of Plasminogen Activator Inhibitor 1

“…The Pla-mediated, wide attack on control of an important hemostatic process in humans, i.e., the fibrinolysis/coagulation balance (32,60,71), represents a considerable difference in pathogenetic potential between the two bacterial species. The omptin Epo also cleaved human PAI-1; this omptin associates with the plant pathogen E. pyrifoliae, which causes pear blight (30), and epo is carried on a mosaic plasmid, pEP36, that is closely related to the virulence plasmid pEA29 of Erwinia amylovora (40). Serpins of mammals and plants share structural features, which include a similar, exposed RCL that is inserted into the catalytic groove of the target proteinases (17).…”

“…Our ongoing research (J. Haiko, unpublished) has shown that Epo is a very poor plasminogen activator, and hence we prefer the name Epo (Erwinia pyrifoliae omptin) instead of PlaA, introduced by McGhee et al (40).…”

Genomics and current genetic understanding of Erwinia amylovora and the fire blight antagonist Pantoea vagans

“…Plasmids appear to be a major factor influencing the pan-genome of E. amylovora. However, although several plasmids of different sizes have been detected in isolates of this species (Chiou and Jones 1991;Foster et al 2004;Laurent et al 1989;McGhee et al 2002;Steinberger et al 1990), the knowledge on this extra-chromosomal material is limited to few strains and plasmids.…”