• Research in Plant Disease
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• v.9 no.3
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• pp.116-120
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• 2003

A PCR method that combines biological and enzymatic amplification of PCR targets was developed for the detection of Pseudomonas syringae pv. actinidiae on kiwifruit leaves. A nested PCR was performed with primers designes from the coding sequence of the cfl gene, which is involved in production of the phytotoxin coronatine. The first and second primer sets efficiently amplified expected 665 and 310-bp fragments, respectively. With two successive amplifications, as few as 20 CFU/ml of P. syringae pv. actinidiae could be detected on ethidium bromide-stained agarose gel. Leaf samples were collected from 4 kiwifruit trees showing yellow halo spots on leaves and incubated in pepton-sucrose broth for 12 h at $16^{\circ}$C before PCR amplification. Positive detection was obtained with one sample, which was proved as a diseased plant in the next spring.

• Research in Plant Disease
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• v.9 no.4
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• pp.213-216
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• 2003

A bacterial disease of tea plants(Camellia sinensis L.) was found in the graftage nursery grown under vinyl house conditions in Suncheon city, Korea, in spring of 2002. The primary symptoms of the disease include small, water-soaked and dark brown spot development on the young leaves. This spot gradually increases in size, especially taking on elongate shape along the midrib or vein of the leaf, and then turns black. The diseased leaves were defoliated easily. Ten strains were isolated from the infected leaf. Inoculation on tea leaf with these isolates produced the same symptoms of naturally infected plants. On the basis of stain reactions, morphological characterization, colony pattern, physiological and biochemical reactions, the bacterium was identified as Pseudomonas syringae pv. theae. This is the first report of brown blight of tea plant in Korea.

• Research in Plant Disease
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• v.10 no.4
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• pp.290-296
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• 2004

Bacterial blossom blight is one of the most important diseases of kiwifruit (Actinidia deliciosa). The disease occurs during flowering in the late May and disease outbreaks associated with rainfall during the flowering season have resulted in a severe reduction in kiwifruit production. The causal organism isolated from diseased blossoms of kiwifruits was identified as Pseudomonas syringae pv, syringae based on the physiological and biochemical characteristics and pathogenicity test. Dead fruit stalks, dead pruned twigs, fallen leaves and soils mainly provided R syringae pv. syringae with overwintering places in the kiwifruit orchards, and the inocula also overwintered on buds, trunks, branches, and twigs on the kiwifruit trees. Among the overwintering places, the incula were detected in the highest frequencies from dead fruit stalks. The population density of P. syringae pv. syringae was speculated to be over $1{\times}10^4$cfu/ml for the bacterial infection, and the optimum temperature for the bacterial growth ranged 20 to $25^{\circ}C$. The highest population density of P. syringae pv. syringae on the overwintering places was detected in May and June when the daily average temperature coincided with the optimum temperature for bacterial growth of P. syringae pv. syringae.

• Journal of Life Science
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• v.25 no.2
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• pp.136-150
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• 2015

Pseudomonas syringae pathovar tabaci is a plant pathogenic bacterium that causes wildfire disease in tobacco plants. In P. syringae pv. tabaci, PsyI, a LuxI-type protein, acts as an AHL synthase, while primary and secondary sequence analysis of PsyR has revealed that it is a homolog of the LuxR-type transcriptional regulator that responds to AHL molecules. In this study, using phenotypic and genetic analyses in P. syringae pv. tabaci, we show the effect of PsyR protein as a quorum-sensing (QS) transcriptional regulator. Regulatory effects of PsyR on swarming motility and production of siderophores, tabtoxin, and N-acyl homoserine lactones were examined via phenotypic assays, and confirmed by quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR). Further qRT-PCR showed that PsyR regulates expression of these virulence genes in response to environmental signals. However, an upstream region of the gene was not bound with purified MBP-PsyR protein; rather, PsyR was only able to shift the upstream region of psyI. These results suggested that PsyR may be indirectly controlled via intermediate-regulatory systems and that auto-regulation by PsyR does not occur.

• Korean Journal of Microbiology
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• v.50 no.3
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• pp.245-248
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• 2014

Pseudomonas syringae pv. actinidiae is the causal agent of bacterial canker in kiwifruit (genus Actinidia). Multilocus sequence analysis of seven housekeeping and 11 type III effector genes differentiated the virulent P. syringae pv. actinidiae isolates worldwide into three groups designated as Psa1-Psa3. In this work, a total of 12 P. syringae pv. Actinidiae strains, including three Psa1, three Psa2, three Psa3 strains isolated from Korea and three Psa3 strains from Italy, were compared based on their phenotypic properties. Strains with different geographic origins had unique growth patterns as demonstrated by growth rate at several temperatures; all tested strains exhibited maximum growth at temperatures below $22^{\circ}C$, while the growth of Psa3 strains was completely inhibited above $30^{\circ}C$. Psa3 strains isolated from Korea had longer lag phases than the Psa3 strains from Italy. The Psa2 strains were different from Psa1 and Psa3 strains in the API 20NE test, in which the Psa2 strains could not utilize potassium gluconate, capric acid and trisodium citrate. Psa3 strains isolated from Korea could hydrolyze esculin. The API ZYM test showed that ${\beta}$-glucosidase activity was detected only from Psa3 strains. The strains belonging to the three Psa groups differed with regard to their susceptibility to ampicillin, novobiocin, and oleandomycin.

• The Korean Journal of Pesticide Science
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• v.19 no.2
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• pp.119-124
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• 2015

Bacterial leaf spot, caused by Pseudomonas syringae pv. syrinage, is a very damaging disease to green pumpkin in Gong-ju and Non-san nursery. However, there is no good method to control the disease in Korea. Growth inhibition of pathogen on medium, control efficacy on seedling stage, and seed treatment effect of 6 anti-bacterial pesticides were investigated for selection of the best pesticide for seed treatment and control of the disease. Growth inhibition zone on King's B medium were the largest by oxytetracycline 170 ppm and oxytetracycline 15 ppm + streptomycin sulfate 188 ppm, oxolinic acid 200 ppm, streptomycin 200 ppm were next respectively. Control efficacy of oxytetracycline 1.5% + streptomycin sulfate 18.8% WP and oxytetracycline 17% WP on seedling stage were 71.4% and 49.4%, respectively. Seed treatment of oxytetracycline 15 ppm + streptomycin sulfate 188 ppm on the artificially inoculated seeds inhibits pathogen growth completely from the treated seeds and 96% control efficacy on grow-out test of the treated seeds. Seed treatment of streptomycin 100 ppm (2,000 dilution of streptomycin 20%) on the artificially inoculated seeds allow 280 cfu/g of pathogen growth from the treated seeds and 60% control efficacy on grow-out test of the treated seeds. Seed treatment of oxytetracycline 85 ppm (2000 dilution of oxytetracycline 17% WP) on the artificially inoculated seeds allow 80 cfu/g of pathogen growth from the treated seeds and 90% control efficacy on grow-out test of the treated seeds. These results suggested that oxytetracycline 1.5% + streptomycin sulfate 18.8% WP was the best pesticide for seed treatment to control of the bacterial spot disease by Pseudomonas syringae pv. syringae.

• The Plant Pathology Journal
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• v.28 no.3
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• pp.295-298
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• 2012

Genetic diversity among Pseudomonas syringae pv. morsprunorum isolates from Prunus mume in Korea and Japan was investigated by comparative sequence analysis of the 16S rRNA gene. The strains included 24 field isolates recovered from P. mume in Korea along with seven Japanese strains. Two strains isolated from P. salicina in Japan, one strain from P. avium in the United Kingdom, and the pathotype strain were also used for comparison with their 16S rRNA gene sequences. Nearly complete 16S rRNA gene sequences were sequenced in all 35 strains, and three sequence types, designated types I, II and III, were identified. Eleven strains consisting of five Korean isolates, five Japanese strains, and one strain from the United Kingdom belonged to type I, whereas the pathotype strain and another 19 Korean isolates belonged to type III. Another four Japanese strains belonged to type II. Type I showed 98.9% sequence homology with type III. Type I and II had only two heterogeneous bases. The 16S rRNA sequence types were correlated with the races of P. syringae pv. morsprunorum. Type I and II strains belonged to race 1, whereas type III isolates were included in race 2. Sequence analyses of the 16S rRNA gene from P. syringae pv. morsprunorum were useful in identifying the races and can further be used for epidemiological surveillance of this pathogen.

• Journal of Microbiology and Biotechnology
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• v.18 no.10
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• pp.1659-1662
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• 2008

Pseudomonas chlororaphis O6 exhibits induced systemic resistance (ISR) against P. syringae pv. tabaci in tobacco. To identify one of the ISR metabolites, O6 cultures were extracted with organic solvents, and the organic extracts were subjected to column chromatography followed by spectroscopy analyses. The ISR bioassay-guided fractionation was carried out for isolation of the metabolite. High-resolution mass spectrometric analysis of the metabolite found $C_{9}H_{9}O_{3}N$ with an exact mass of 179.0582. LC/MS analysis in positive mode showed an $(M+H)^{+}$ peak at m/z 180. Nuclear magnetic resonance ($^{1}H,\;^{13}C$) analyses identified all protons and carbons of the metabolite. Based on the spectroscopy data, the metabolite was identified as 4-(aminocarbonyl) phenylacetate (4-ACPA). 4-ACPA applied at 68.0 mM exhibited ISR activity at a level similar to 1.0 mM salicylic acid. This is the first report to identify an ISR metabolite produced by P. chlororaphis O6 against the wildfire pathogen P. syringae pv. tabaci in tobacco.

• Proceedings of the Korean Society of Life Science Conference
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• 2008.10a
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• pp.72.2-72.2
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• 2008

• Proceedings of the Korean Society of Life Science Conference
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• 2007.10a
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• pp.69.1-69.1
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• 2007

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