• Korean Journal of Breeding Science
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• v.41 no.3
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• pp.314-318
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• 2009

A new rice cultivar "Jinbaek" carrying Xa3 and xa5 was derived from the cross between 'HR15204-38-3' with xa5 gene resistant to bacterial blight K1, K2, K3 and K3a, and F1 plant derived from the cross between Junam and Sindongjin with Xa3 gene. "Jinbaek" has approximately 125 days of growth duration from transplanting to harvesting in the west-southern coastal and Honam plain of Korea. Culm length of "Jinbaek" is 71 cm. In reaction to biotic stresses, it shows moderate resistance to blast, and wide spectrum resistance to bacterial blight pathogen, K1, K2, K3, and K3a but susceptible to rice stripe virus and blast. The milled rice of "Jinbaek" exhibits translucent, relatively clear non-glutinous endosperm and midium short grain. It has lower amylose content (18.8%) and protein content (6.2%) compared with Nampyeong. The milled rice yield of this cultivar was 5.30 MT/ha in local adaptability test of three years from 2006 to 2008. This cultivar would be adaptable to the bacterial blight-prone area in the south-western coast and Honam plain of Korea.

• The Korean Journal of Pesticide Science
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• v.18 no.4
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• pp.422-428
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• 2014

Endophytic bacterial strains from root tissue of strawberry were screened for their efficacy in growth improvement and control of Phytophthora blight disease of chili pepper plant under greenhouse condition. Plants treated with the strain EP103, identified as Pseudomonas fluorescens, showed growth improvement in terms of fresh weight and root length compared to the untreated control and other endophytic strains. When challenged with Phytophthora capsici, there was significant reduction of disease in EP103 treated plants with an efficacy of 78.7%. There was no direct inhibition of the target pathogen by EP103 when tested under in vitro antibiosis assay. Analysis of differential expression of selected marker genes for induced systemic resistance (ISR) in plants treated with EP103 and challenged with P. capsici showed up-regulation of PR1 and PR10 pathogenesis-related (PR) proteins. PCR analysis showed that EP103 produced secondary metabolites such as pyoluteorin, pyrrolnitrin, hydrogen cyanide and orfamide A. This study indicated the potential of endophytic P. fluorescens strain EP103 as an efficient biocontrol agent against P. capsici in chili pepper plant.

• Journal of Yeungnam Medical Science
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• v.1 no.1
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• pp.41-48
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• 1984

The soil bacterium Agrobacterium tumefaciens is a plant pathogen that cause3 crown gall tumors by infecting the wounded dicotyledonous plants and subsequent integration of bacterial DNA into plant nuclear DNA. Virulent A. tumefaciens strains harbor a large Ti (tumor-inducing) plasmid that carries genes essential for tumorigenesis. In the present study, 13 strains (Malus pumila Mill; $A_{1-3}$, Populus monilifera; $W_{1-6}$, Populus tomentiglandlosa; $P_{1-3}$ and Rosa species; $R_1$) of Agrobacterium isolated in korean crown gall tumors and plasmids were observed in 6 strains ($W_2$, $W_3$, $W_6$, $P_1$, $P_3$ and $A_2$). The test for crown gall tumor formation was resulted only in ATCC15955 and $KW_2$ strains inoculated into the stem of sun flower and the development was observed for 4 and 6 weeks after inoculation. Above two Ti plasmids (pTi) were purified by cesium chloride-ethidium bromide density gradient centrifugation and digested with restriction enzyme and fragments of pTiATCC 15955 and $pTiKW_2$ observed by EcoR I ; 25&27, Hind III; 23&21, BamH I ; each 20 and Hpa I ; 12&27, and sizes of pTiATCC15955 and and $pTiKW_2$ calculated as 200 and 87 kbases. Octopine was isolated from tumor tissue ($W_{1-6}$ and $P_{1-3}$) and these strains confirmed as octopine type.

• Research in Plant Disease
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• v.10 no.1
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• pp.58-62
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• 2004

Contamination level and characteristics of Ralstonia solanacearum in soil of greenhouses cultivating tomato plants in Chungbuk province was determined. R. solanacearum was isolated with the semiselective media in 27 greenhouse soil samples out of 133 greenhouses soil investigated, which indicates 20.3 ％ of tomato cultivating greenhouses in Chungbuk contaminated with the bacterial wilt pathogen. Density of R. solanacearum was estimated to 10$^{2.4}$ cfu/g in the contaminated soil. All 71 isolates of R. solanacearum which containing 12 isolates from the diseased tomato plants were race 1, ann 35 isolates of them were biovar 3 and 36 isolates were biovar 4. More than 88％ of 71 isolates were inhibited growth on nutrient agar containing oxolinic acid 0.5 $\mu\textrm{g}$/ml, streptomycin 25 $\mu\textrm{g}$/ml, tetracycline 5 $\mu\textrm{g}$/ml and cupric sulfate 375 $\mu\textrm{g}$/ml (1.5 mM). The 11.3％, 4.2％ and 5.6 ％ of the isolates can grow on nutrient agar containing 10 times more oxolinic acid, streptomycin, tetracycline than minimal inhibitory concentration of the sensitive strains. Five isolates were resistant to 2 bactericides and one isolates was resistant to all 3 bactericides.

• Journal of fish pathology
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• v.22 no.3
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• pp.317-326
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• 2009

This study has shown the screening of anti-bacterial activity of three Indian medicinal plant choloroform : methanol (50:50) solvent leaf extracts (i.e. Azadirachta indica, Ocimum sanctum, and Curcuma longa) with different concentrations (10, 5, 2.5, 1.25, 0.625, 0.312, and 0.156 mg/ml) under in vitro conditions against fish pathogenic bacteria, Aeromonas hydrophila, Streptococcus iniae, Vibrio harveyi, V. anguillarum, and Edwardsiella tarda isolated from olive flounder farms, Jeju Island, South Korea. The anti-microbial activity of the A. indica and O. sanctum extracts yielded the zones of growth inhibition (ZI) was 3 and 1mm against A. hydrophila at concentration of 0.156 mg/ml when compared to that of tetracycline standard (3 mm). At highest concentration (10 mg/ml) of A. indica, O. sanctum, and C. longa, high inhibition was 9, 7, and 6 mm when compared to that of tetracycline (11 mm) against A. hydrophila. The minimum inhibitory concentration (MIC) of A. indica, O. sanctum, and C. longa at 0.156 mg/ml that yield 9, 10, and 13 CFU/ml for A. hydrophila, 16, 22, and 25 CFU/ml for S. iniae and 18, 22, and 23 CFU/ml for E. tarda compared to the tetracycline. At highest concentration (10 mg/ml) of the three extracts was better inhibiting the growth of A. hydrophila, S. iniae and E. tarda. A. indica, O. sanctum, and C. longa were determined to the potential antioxidant activityon the basis of their scavenging activity of the stable 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical. A. indica extract was 0.625 mg/ml which indicated that the strong anti-oxidant activity. However, O. sanctum and C. longa extracts showed weak anti-oxidant activity at this concentration. Hence, in vitro assay among the pathogens, A. hydropila is better inhibitory activity of the extracts. It is evident that the Indian medicinal plants extracts were subjected to its effectiveness against A. hydrophila, S. iniae, and E.tarda at low concentrations. The obtained results in the present study suggested that the Indian plant extracts is a prevention tools for Korean olive flounder aquaculture pathogens and its need further advance investigation.

• Korean Journal of Microbiology
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• v.46 no.3
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• pp.248-254
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• 2010

To define the optimum conditions for the mass production of four antifungal Pseudomonas spp. isolated from soil, we have investigated culture conditions and effects of various nutrient sources on the bacterial growth and evaluated antagonistic activity against Rhizoctonia solani and Sclerotinia homoeocarpa, plant pathogens. The optimum temperature and pH for the growth of these isolates were determined as pH 7.0 and $20^{\circ}$ or $25^{\circ}C$, respectively. Sucrose, tryptone, and $K_2HPO_4$ generally were more adequate for better growth as carbon, nitrogen and mineral source, respectively. The nutrient sources were also found to be very effective for high antifungal activities against R. solani and S. homoeocarpa. It was elucidated that YUD-F group (P. mandelii and P. fluorescens), which inhabit regions at relatively low temperature, had more broad spectrum and higher antifungal activity than YUD-O group (P. trivialis and P. jessenii) generally against R. solani and S. homoeocarpa. It is thought that the differences of the average temperature in the various habitats of Pseudomonas spp. influence the optimal growth temperature and antifungal activity. Especially, Pseudomonas spp. of YUD-O group showed the better antifungal activity against dollar spot caused by S. homoeocarpa, but showed relatively weaker antifungal activity against brown patch caused by R. solani.

• The Korean Journal of Mycology
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• v.41 no.4
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• pp.248-254
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• 2013

A Gram-negative bacterium was isolated from mushroom media that markedly reduces the level of extracellular toxins (i.e., tolaasins) produced by Pseudomonas tolaasii, the most destructive pathogen of cultivated mushrooms. The HC1 strain was selected as detoxifying tolaasin by bioassay on potato and it was identified Pseudomonas sp. by the cultural, morphological and physiological characteristics, and analysis of the 16S rRNA. The isolated bacterium is saprophytic but not parasitic nor pathogenic to cultivation mushroom. The isolated bacterium for P. tolaasii cell, was sufficient for detoxification in vitro. Inoculation of the isolated bacterium prevents the development of bacterial disease in Pleurotus ostreatus, Flammunia velutipes and Agaricus bisporus. Control efficacy of brown blotch of strain HC1 treatment was 69, 68 and 55% on Agaricus bisporus, Flammulina velutipes and Pleurotus ostreatus, respectively. The suppressive bacterium may be useful in future for the development of biocontrol system and the construction of genetically modified edible fungi resistant to the disease caused by P. tolaasii.

• Journal of Mushroom
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• v.12 no.1
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• pp.35-40
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• 2014

Several bacteria are known as the causal agents of diseases of the cultivated button mushroom(Agaricus bisporus) and oyster mushroom(Pleurotus ostreatus). Pseudomonas tolaasii is the causal agent of brown blotch disease of commercial mushrooms. Pseudomonas sp. HC1 is a potent biological control agent to control brown blotch disease caused by Pseudomonas tolaasii. This can markedly reduce the level of extracellular toxins (i.e., tolaasins) produced by Pseudomonas tolaasii, the most destructive pathogen of cultivated mushrooms. To define the optimum conditions for the mass production of the Pseudomonas sp. HC1, we have investigated optimum culture conditions and effects of various nutrient source on the bacterial growth. The optimum initial pH and temperature were determined as pH 5.0 and $20^{\circ}C$, respectively. The optimal culture medium for the growth of tolaasin inhibitor bacterium was determined as follows: 0.9% dextrin, 1.5% yest extract, 0.5% $(NH_4)_2HPO_4$, 4mM $FeCl_3$, and 3.0% cysteine.

• Korean Journal of Veterinary Service
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• v.39 no.4
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• pp.211-219
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• 2016

For determining the prevalence of major enteric pathogens, clinical examination and etiological diagnosis were carried out on 75 Korean pig farms. Enteric disease-suspected signs were observed in 90.7% of the farms and the incidence and severity were higher in younger age groups of the pigs. Five of seven pathogens were detected in 375 fecal samples collected from the 75 farms, and the farm-level prevalence of porcine rotavirus group A (PoRVA), pathogenic Escherichia (E.) coli, Lawsonia (L.) intracelluraris, Salmonella spp., and Brachyspira (B.) hyodysenteriae was 54.7%, 54.7%, 16.0%, 10.7% and 2.7%, respectively. PoRVA was extensively infected in suckling and weaning pig groups. The prevalence of pathogenic E. coli was highest in suckling period, and after the period, it exhibited a tendency to decrease. Salmonella spp. and L. intracelluraris were detected in all feeding groups of pigs in a ratio of 1.3~6.7%. B. hyodysenteriae was detected in 1.3~2.7% of growing and fattening pig groups but not detected in suckling and weaning pig groups. At least one or more pathogens were detected in 30.1% of 375 fecal samples. Among these, 25.0% or 5.1% of cases were single or mixed infection. Enteric disease signs of the pigs were significantly co-related with the detection of PoRVA, pathogenic E. coli or Salmonella spp. (P<0.01) but not with L. intracelluraris or B. hyodysenteriae (P>0.05). Conclusively, it will be expected that these data obtained in this study are very useful for subsequent studies and prevention strategies for swine enteric disease in Korean pig farms.

• 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.