• The Plant Pathology Journal
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• v.30 no.3
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• pp.245-253
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• 2014

Antimicrobial peptides (AMPs) are small but effective cationic peptides with variable length. In previous study, four hexapeptides were identified that showed antimicrobial activities against various phytopathogenic bacteria. KCM21, the most effective antimicrobial peptide, was selected for further analysis to understand its modes of action by monitoring inhibitory effects of various cations, time-dependent antimicrobial kinetics, and observing cell disruption by electron microscopy. The effects of KCM21 on Gram-negative strain, Pseudomonas syringae pv. tomato DC3000 and Gram-positive strain, Clavibacter michiganensis subsp. michiganensis were compared. Treatment with divalent cations such as $Ca^{2+}$ and $Mg^{2+}$ inhibited the bactericidal activities of KCM21 significantly against P. syringae pv. tomato DC3000. The bactericidal kinetic study showed that KCM21 killed both bacteria rapidly and the process was faster against C. michiganensis subsp. michiganensis. The electron microscopic analysis revealed that KCM21 induced the formation of micelles and blebs on the surface of P. syringae pv. tomato DC3000 cells, while it caused cell rupture against C. michiganensis subsp. michiganensis cells. The outer membrane alteration and higher sensitivity to $Ca^{2+}$ suggest that KCM21 interact with the outer membrane of P. syringae pv. tomato DC3000 cells during the process of killing, but not with C. michiganensis subsp. michiganensis cells that lack outer membrane. Considering that both strains had similar sensitivity to KCM21 in LB medium, outer membrane could not be the main target of KCM21, instead common compartments such as cytoplasmic membrane or internal macromolecules might be a possible target(s) of KCM21.

• Korean Journal of Veterinary Research
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• v.56 no.2
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• pp.67-74
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• 2016

Tomato extract has been shown to exert antiplatelet activity in vitro and to change platelet function ex vivo, but with limitations. In this study, antiplatelet activity of water soluble tomato concentrate (Fruitflow I) and dry water soluble tomato concentrate (Fruitflow II) was investigated using rat platelets. Aggregation was induced by collagen and adenosine diphosphate and granule-secretion, $[Ca^{2+}]_i$, thromboxane B2, cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) levels were examined. The activation of integrin ${\alpha}_{IIb}{\beta}_3$ and phosphorylation of signaling molecules, including mitogen-activated protein kinase (MAPK) and PI3K/Akt, were investigated by flow cytometry and immunoblotting, respectively. Prothrombin time (PT) and activated partial thromboplastin time (aPTT) were examined. Moreover, in vivo thrombus weight was tested by an arteriovenous shunt model. Fruitflow I and Fruitflow II significantly inhibited agonist induced platelet aggregation, adenosine triphosphate and serotonin release, $[Ca^{2+}]_i$, and thromboxane B2 concentration, while having no effect on cAMP and cGMP levels. Integrin ${\alpha}_{IIb}{\beta}_3$ activation was also significantly decreased. Moreover, both concentrates reduced phosphorylation of MAPK pathway factors such as ERK, JNK, P38, and PI3K/Akt. In vivo thrombus formation was also inhibited. Taken together, these concentrates have the potential for ethnomedicinal applications to prevent cardiovascular ailments and can be used as functional foods.

• Research in Plant Disease
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• v.14 no.1
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• pp.32-36
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• 2008

Bacterial wilt caused by Ralstonia solanacearum has become a severe problem on tomato in Korea and no effective control measures are available yet. Pseudomonas species play key roles for the biocontrol of many plant diseases especially in soil. A rhizobacterial population of 150 Pseudomonas strains, isolated from the rhizosphere soil of various plants grown at different sites, was screened for 2,4-diacetylphloroglucinol producing gene (PhlD) by PCR. Two strains (P83 and P84) among them were found to be phlD positive. When the isolates were analysed by 16S rDNA (Sensu Stricto), all isolates yielded amplified products of 1,018bp. Of the 150 isolates of Pseudomonas spp., a bacterial strain P. putida P84 isolated from tomato rhizosphere showed to suppress a wide range of phytopathogenic bacteria in vitro. The best source of carbon for P84 strain were glucose, arabinose, inositol and melibiose. In greenhouse experiments, P84 strain suppressed the development of bacterial wilt in tomato with a control value of 60%.

• Research in Plant Disease
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• v.14 no.1
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• pp.1-9
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• 2008

The severe damage induced by the important viruses of Rice stripe virus (RSV), Cucumber green mottle mosaic virus (CGMMV), Melon necrotic spot virus (MNSV), Tomato spotted wilt virus (TSWV) and Tomato bushy stunt virus (TBSV) was described on major crops in Korea. In 2007, the plot incidence rate of RSV was 100% on the precocious rice cultivars at the Western coastal provinces of Gyeonggido, Chungcheongnamdo, Jellabugdo and Jellanamdo, and Jejudo. RSV occurred in 2,441 ha with incidence rate of 70% over at 5 areas of Seocheon, Seosan, Boryung, Hongsung and Buyou in Chungcheongnamdo. At 4 areas of Buan, Gimje, Gunsan and Gochang in Jellabukdo, RSV occurred in 2.016 ha. CGMMV occurred on watermelon in 4.6 ha at Cheongyang area, and its outbreak was also 890 ha on oriental melon for 120 farmers with the incidence area of 23% against total cultivation areas of Seongju. MNSV was recorded firstly on watermelon in 2006 at Andong and it spread to 3 areas of Hapcheon, Gochang and Yanggu. TSWV occurred firstly at Danggin in Chungcheongnamdo in 2005. TSWV in 2006 spread to 6 areas; Taian, Hongsung and Seosan in Chungcheongnando, Namwon in Jellabukdo, and Sunchon and Kwangju in Jellanamdo. In 2007, TSWV covered 17 areas of western and southern parts; the 5 area including Taian in Chungcheongnamdo, Kwangju in Jellanamdo, Bucheon in Gyunggido, and so forth. TBSV was described firstly on table tomato at Sacheon in Kyungsangnamdo in 2004. TBSV occurred on cherry tomato at Chungju in 2006 and on table tomato at Busan area.

• Research in Plant Disease
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• v.15 no.3
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• pp.222-229
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• 2009

A Pseudomonas strain SG3 producing biosurfactant and showing antifungal and insecticidal activities was isolated from agricultural soil severely contaminated with machine oils. The antagonistic bacterium inhibited mycelial growth of all of the tested fungal pathogens. The fermentation broth of SG3 also effectively suppressed the development of various plant diseases including rice blast, tomato gray mold, tomato late blight, wheat leaf rust, barley powdery mildew and red pepper anthracnose. An antifungal substance was isolated from the fermentation broth of SG3 by ethyl acetate partitioning, silica gel column chromatography and preparative HPLC under the guide of bioassay. The chemical structure of the antifungal substance was determined to be rhamnolipid B by mass and NMR spectral analyses. The antifungal biosurfactant showed a potent in vivo antifungal activity against gray mold and late blight on tomato plants. In addition, rhamnolipid B inhibited mycelial growth of B. cinerea causing tomato gray mold and zoospore germination and mycelial growth of P. infestans causing tomato late blight. Pseudomonas sp. SG3 producing rhamnolipid B could be used as a new biocontrol agent for the control of plant diseases occurring on tomato plants.

• Research in Plant Disease
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• v.17 no.1
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• pp.44-51
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• 2011

The aim of this study was to develop specific and sensitive PCR-based procedures for simultaneous detection of economically important plant seed infection pathogenic bacteria and virus, Xanthomonns campestris pv. vesicatoria (Xcv), Clavibacter michiganensis subsp. michiganensis (Cmm), Erwinia carotovora subsp. carotovora (Ecc), Pepper mild mottle virus (PMMoV) and Tobacco mild green mosaic virus (TMGMV) in pepper and tomato seeds. Most of pepper and tomato bacterial and virus diseases are responsible for germination and growth obstruction. PCR with arbitral primers: selection of specific primers, performance of PCR with specific primers and determination of the threshold level for pathogens detection. To detect simultaneously the Xcv, Cmm, Ecc, PMMoV and TMGMV in pepper and tomato seeds, five pairs (Cmm-F/R, Ecc-F/R, Xcv-F/R, PMMoV-F/R, TMGMV-F/R) of specific primer were synthesized by primer-blast program. The multiplex PCR for the five pathogens in pepper and tomato seeds could detect specially without interference among primers and/or cDNA of plant seeds and other plant pathogens. The PCR result for pathogen detection using 20 commercial pepper and 10 tomato seed samples, Ecc was detected from 4 pepper and 2 tomato seed samples, PMMoV was detected from 1 pepper seed sample, and PMMoV and TMGMV were simultaneously detected from 1 pepper seed sample.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2005.04a
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• pp.87.1-87.1
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• 2005

• Proceedings of the Korean Society of Plant Biotechnology Conference
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• 2002.04b
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• pp.167-167
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• 2002

• Research in Plant Disease
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• v.17 no.2
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• pp.142-147
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• 2011

In order to develop a environmentally friendly control protocol for managing tomato leaf mold disease in the field, we employed bacteria- and fungi-based commercially available microbial preparations. The field experiment was conducted from April to July in 2010. Average incidence rates tomato leaf mold caused by Fulvia fulva were 13.1% at the two plastic houses located in Jangsung, Jeonnam area. Initially 11 microbial preparations were tested for antifungal activity against F. fulva in vitro. Among them, 7 selected preparations showed to be inhibited the mycelial growth of the fungal pathogen over 50%. Four microbes suppressed disease incidence as much 50% under greenhouse condition. Eventually in the field two microbial products including Bacillus subtilis GB-0365 and B. subtilis KB-401 respectively were showed control value up to 71.8% for four times sprays from 20 days to 70 days after transplanting. Furthermore, the control value of three times spray program demonstrated 79.3%. Efficacy of the three and four spray programs was more effective than that of non-spray control treatment. Our results indicated that adjustment of application method of commercially available microbial preparation could be used to control a target plant disease as an effective and efficient crop protection system for organic farming.

• Research in Plant Disease
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• v.20 no.4
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• pp.303-306
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• 2014

Tomato yellow leaf curl virus (TYLCV) disease survey of tomato plants cultivated at Youngam, Changseong and Hwasun in Jeonnam Province was conducted in 2012 to 2013. To detect TYLCV in the field, PCR assay was performed using genomic DNAs extracted from tomato samples. According to cropping pattern, 23 and 59.4% of TYLCV infections were shown in semi-forcing and retarding cropping systems, respectively, and the frequencies of diseased plants were 0.4 and and 13.1% in the two cropping systems, respectively. Especially, TYLCV incidences in the susceptible varieties were 24.3 and 83.0% in semi-forcing and retarding cropping systems, respectively. Resistant varieties showed 9.1% infection in retarding cropping system but did not in semi-forcing cropping system. Also, TYLCV was occurred on early June after transplanting on April and at approximate 20 days after transplanting on August or September.