• The Plant Pathology Journal
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• v.21 no.2
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• pp.127-131
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• 2005

In this comparative study, the effects of temperature, pH, and bactericides on the growth of Erwinia pyrifoliae and Erwinia amylovora were investigated. The maximum temperature for the growth of both Erwinia species was estimated to be $36{\circ}C$. The maximum specific growth rates of E. pyrifoliae and E. amylovora were observed at $27{\circ}C$ and $28{\circ}C$, respectively, and no significant growth differences were shown at their optimum temperatures. However, at lower temperatures ranging from 12-$21{\circ}C$, E. pyrifoliae showed higher growth rates with doubling times shorter than those of E. amylovora. Distinct growth rates at these temperatures revealed that E. pyrifoliae is more cold-tolerant than E. amylovora. The optimum pH for the growth of both pathogens was 7.5 and growth was not seen at pH ${\le}$ 5.0 and ${\ge}$ 10.0. These results showed that the effect of pH on the growth of E. pyrifoliae and E. amylovora was similar. Minimum inhibitory concentrations (MICs) of copper sulfate, oxolinic acid, streptomycin, and tetracycline, which inhibited growth of E. pyrifoliae and E. amylovora, were determined. The strains of both pathogens were able to grow at 0.08-0.32 mM copper sulfate, but not at higher concentrations. However, none of the tested strains grew in the presence of oxolinic acid (0.001 mM), streptomycin (0.1 mM), and tetracycline (0.01 mM) concentrations. These results suggested that all strains of both Erwinia species were sensitive to tested bactericides and indicated no occurrence of resistant strains of E. pyrifoliae in Korea.

• The Plant Pathology Journal
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• v.39 no.1
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• pp.141-148
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• 2023

Black shoot blight disease caused by Erwinia pyrifoliae has serious impacts on quality and yield in pear production in Korea; therefore, rapid and accurate methods for its detection are needed. However, traditional detection methods require a great deal of time and fail to achieve absolute quantification. In the present study, we developed a droplet digital polymerase chain reaction (ddPCR) method for the detection and absolute quantification of E. pyrifoliae using a pair of species-specific primers. The detection range was 10³-10⁷ copies/ml (DNA templates) and cfu/ml (cell culture templates). This new method exhibited good linearity and repeatability and was validated by absolute quantification of E. pyrifoliae DNA copies from samples of artificially inoculated immature pear fruits. Here, we present the first study of ddPCR assay for the detection and quantification of E. pyrifoliae. This method has potential applications in epidemiology and for the early prediction of black shoot blight outbreaks.

• The Plant Pathology Journal
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• v.34 no.5
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• pp.445-450
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• 2018

Bacteriophages, bacteria-infecting viruses, have been recently reconsidered as a biological control tool for preventing bacterial pathogens. Erwinia amylovora and E. pyrifoliae cause fire blight and black shoot blight disease in apple and pear, respectively. In this study, the bacteriophage phiEaP-8 was isolated from apple orchard soil and could efficiently and specifically kill both E. amylovora and E. pyrifoliae. This bacteriophage belongs to the Podoviridae family. Whole genome analysis revealed that phiEaP-8 carries a 75,929 bp genomic DNA with 78 coding sequences and 5 tRNA genes. Genome comparison showed that phiEaP-8 has only 85% identity to known bacteriophages at the DNA level. PhiEaP-8 retained lytic activity up to $50^{\circ}C$, within a pH range from 5 to 10, and under 365 nm UV light. Based on these characteristics, the bacteriophage phiEaP-8 is novel and carries potential to control both E. amylovora and E. pyrifoliae in apple and pear.

• Journal of Microbiology and Biotechnology
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• v.14 no.4
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• pp.872-876
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• 2004

The plant pathogen Erwinia pyrifoliae was infected with bacteriophage PEa1(h), which produced a translucent halo plaque when grown on a lawn of E. pyrifoliae. To investigate the function of an exopolysaccharide (EPS)-depolymerase in the growth of E. pyrifoliae, an EPS-depolymerase gene was synthesized using the PCR method and sequenced. The synthesized gene was then transferred to E. pyrifoliae. The transformed E. pyrifoliae did not produce any ooze, and its growth was inhibited. However, the EPS-depolymerase did not appear to induce cell death. Accordingly, the present results suggest that an EPS-depolymerase may be effective in inhibiting the cell growth or infection of the pathogen E. pyrifoliae.

• The Plant Pathology Journal
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• v.36 no.5
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• pp.428-439
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• 2020

Erwinia pyrifoliae is a Gram-negative bacterial plant pathogen that causes black shoot blight in apple and pear. Although earlier studies reported the genome comparison of Erwinia species, E. pyrifoliae strains for such analysis were isolated in 1996. In 2014, the strain E. pyrifoliae EpK1/15 was newly isolated in the apple tree showing black shoot blight in South Korea. This study aimed to better understand the similarities and differences caused by natural variations at the genomic level between newly isolated E. pyrifoliae EpK1/15 and the strain Ep1/96, which were isolated almost 20 years apart. Several comparative genomic analyses were conducted, and Clusters of Orthologous Groups of proteins (COG) database was used to classify functional annotation for each strain. E. pyrifoliae EpK1/15 had similarities with the Ep1/96 strain in stress-related genes, Tn3 transposase of insertion sequences, type III secretion systems, and small RNAs. The most remarkable difference to emerge from this comparison was that although the draft genome of E. pyrifoliae EpK1/15 was almost conserved, Epk1/15 strain had at least three sorts of structural variations in functional annotation according to COG database; chromosome inversion, translocation, and duplication. These results indicate that E. pyrifoliae species has gone natural variations within almost 20 years at the genomic level, and we can trace their similarities and differences with comparative genomic analysis.

• The Plant Pathology Journal
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• v.38 no.3
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• pp.194-202
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• 2022

Erwinia amylovora and Erwinia pyrifoliae cause fire blight and black-shoot blight, respectively, in apples and pears. E. pyrifoliae is less pathogenic and has a narrower host range than that of E. amylovora. Fire blight and black-shoot blight exhibit similar symptoms, making it difficult to distinguish one bacterial disease from the other. Molecular tools that differentiate fire blight from black-shoot blight could guide in the implementation of appropriate management strategies to control both diseases. In this study, a primer set was developed to detect and distinguish E. amylovora from E. pyrifoliae by conventional polymerase chain reaction (PCR). The primers produced amplicons of different sizes that were specific to each bacterial species. PCR products from E. amylovora and E. pyrifoliae cells at concentrations of 10⁴ cfu/ml and 10⁷ cfu/ml, respectively, were amplified, which demonstrated sufficient primer detection sensitivity. This primer set provides a simple molecular tool to distinguish between two types of bacterial diseases with similar symptoms.

• The Plant Pathology Journal
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• v.26 no.3
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• pp.267-270
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• 2010

We designed a sensitive and specific PCR-based method with enterobacterial repetitive intergenic consensus (ERIC) primer to detect Erwinia pyrifoliae, which cause shoot blight in Asian pear, from a mixed culture and infected plant materials. The primers specifically detected only E. pyrifoliae and showed no cross-reactivity with other bacterial phytopathogens.

• Korean Journal of Microbiology
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• v.54 no.1
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• pp.69-70
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• 2018

Erwinia pyrifoliae is a Gram-negative bacterium causing black shoot blight in apple and Asian pear trees. E. pyrifoliae strain EpK1/15 was isolated in 2014 from an apple twig from the Pocheon, Gyeonggi-do, South Korea. In this study, we report the draft genome sequence of E. pyrifoliae EpK1/15 using PacBio RS II platform. The draft genome is comprised of a circular chromosome with 4,027,225 bp and 53.4% G + C content and a plasmid with 48,456 bp and 50.3% G + C content. The draft genome includes 3,798 protein-coding genes, 22 rRNA genes, 77 tRNA genes, 13 non-coding RNA genes, and 231 pseudo genes.

• The Plant Pathology Journal
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• v.38 no.4
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• pp.355-365
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• 2022

Erwinia amylovora and E. pyrifoliae are the causative agents of destructive diseases in both apple and pear trees viz. fire blight and black shoot blight, respectively. Since the introduction of fire blight in Korea in 2015, the occurrence of both pathogens has been independently reported. The co-incidence of these diseases is highly probable given the co-existence of their pathogenic bacteria in the same trees or orchards in a city/district. Hence, this study evaluated whether both diseases occurred in neighboring orchards and whether they occurred together in a single orchard. The competition and virulence of the two pathogens was compared using growth rates in vitro and in planta. Importantly, E amylovora showed significantly higher colony numbers than E. pyrifoliae when they were co-cultured in liquid media and co-inoculated into immature apple fruits and seedlings. In a comparison of the usage of major carbon sources, which are abundant in immature apple fruits and seedlings, E. amylovora also showed better growth rates than E. pyrifoliae. In virulence assays, including motility and a hypersensitive response (HR), E. amylovora demonstrated a larger diameter of travel from the inoculation site than E. pyrifoliae in both swarming and swimming motilities. E. amylovora elicited a HR in tobacco leaves when diluted from 1:1 to 1:16 but E. pyrifoliae does not elicit a HR when diluted at 1:16. Therefore, E. amylovora was concluded to have a greater competitive fitness than E. pyrifoliae.

• The Plant Pathology Journal
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• v.19 no.6
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• pp.294-300
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• 2003

Bacterial strains were isolated from diseased samples of shoot blight collected from different pear growing orchards of Chuncheon, Korea from 1995 to 1998. Forty-nine strains showed their pathogenicity on immature fruit and shoot of pear. Microbiological, physiological, and biochemical tests were performed on these pathogenic strains. One strain, designated as WT3 in this study, was selected as a representative strain as it was collected from the first outbreak area in Jichonri, Chuncheon in 1995. Further detailed characterization of the strain WT3 was done by PCR amplification using specific primers described previously for distinguishing Erwinia pyrifoliae from its close pathogen Erwinia amylovora. Based on phenotypical, biochemical, and molecular analyses, strain WT3 was identified as a shoot blight pathogen which was the same as E. pyrifoliae Ep16 previously described by a German group in 1999.