• Preventive Nutrition and Food Science
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• v.16 no.4
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• pp.376-380
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• 2011

We investigated the total phenolic and flavonoid contents and the antimicrobial activity of ethanol extracts obtained from Saussurea lappa C.B. Clarke. The ethanol extracts of S. lappa C.B. Clarke were fractionated with various solvents (n-hexane, chloroform, and n-butanol). The antimicrobial activity of S. lappa C.B. Clarke was examined by disc-diffusion and micro-dilution susceptibility assays with six food-borne pathogens, and compared to that of the synthetic antibiotics. It is found that the S. lappa C.B. Clarke ethanol extract and n-hexane fraction have strong activity against B. cereus and V. parahaemolyticus strains compared to ampicillin. The inhibitory concentration ($IC_{50}$) values of hexane fraction against L. monocytogenes, B. cereus, and B. subtilis were 62.5, 250 and 500 ppm, respectively. Therefore, these data suggest that S. lappa C.B. Clarke may be useful as antimicrobial agents against food-borne pathogens.

• Research in Plant Disease
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• v.19 no.2
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• pp.121-123
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• 2013

The strains of Colletotrichum gloeosporioides, C. coccodes, C. acutatum isolated from black raspberry were pathogenic to apple and strawberry after dropping inoculation, but showed weak pathogenicity in hot-pepper and tomato. The anthracnose pathogens of C. gloeosporioides, C. orbiculare, C. acutatum isolated from apple, hot-pepper and pumpkin showed pathogenicity in black raspberry. Moreover, the anthracnose pathogens isolated from apple caused disease symptoms in non-wounded inoculation.

• Mycobiology
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• v.49 no.1
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• pp.69-77
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• 2021

The application of antagonistic fungi for plant protection has attracted considerable interest because they may potentially replace the use of chemical pesticides. Antipathogenic activities confirmed in volatile organic compounds (VOCs) from microorganisms have potential to serve as biocontrol agents against pre- and post-harvest diseases. In the present study, we investigated Galactomyces fungi isolated from rotten leaves and the rhizosphere of cherry tomato (Lycopersicon esculentum var. cerasiforme). VOCs produced by Galactomyces fungi negatively affected the growth of phytopathogenic fungi and the survival of nematodes. Mycelial growths of all nine examined phytopathogenic fungi were inhibited on agar plate, although the inhibition was more intense in Athelia rolfsii JYC2163 and Cladosporium cladosporioides JYC2144 and relatively moderate in Fusarium sp. JYC2145. VOCs also efficiently suppressed the spore germination and mycelial growth of A. rolfsii JYC2163 on tomatoes. The soil nematode Caenorhabditis elegans exhibited higher mortality in 24 h in the presence of VOCs. These results suggest the broad-spectrum activity of Galactomyces fungi against various plant pathogens and the potential to use VOCs from Galactomyces as biocontrol agents.

• Korean Journal of Environmental Agriculture
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• v.35 no.3
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• pp.191-201
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• 2016

BACKGROUND: The aim of this study was to investigate the antimicrobial effects of the ethanol extracts from various medicinal herbs against plant pathogens to understand the possible the crop protection agents.METHODS AND RESULTS: Among the tested medicinal herbs, Zizyphus jujuba ethanol extract had the potent antimicrobial activity against Phytophthora capsici, Erwinia carotovorum subsp. carotovora, Pseudomonas syringae pv. syringae and Ralstonia solanacearum. The major constituents of Z. jujuba were identified to eugenol(40.45%), dodecanoic acid(18.40%), β-caryophyllene (10.05%) and isoeugenol(9.85%) by GC/MS. Eugenol and isoeugenol had strong inhibitory activity on spore germination against P. capsici and growth against E. carotovorum subsp. carotovora, P. syringae pv. syringae and R. solanacearum.CONCLUSION: In this regard, eugenol and isoeugenol were found to be responsible for the antimicrobial activity of Z. jujuba ethanol extract against plant pathogens. In addition, Z. jujuba ethanol extract, eugenol and isoeugenol can be used the potent antimicrobial agents.

• Korean Journal of Organic Agriculture
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• v.24 no.4
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• pp.945-955
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• 2016

To date, chemical managements of plant bacterial diseases are complicated by limitations on use of antibiotics in agriculture, antibiotic resistance development, and limited efficacy of alternative control agents. In this study, thus, we performed screening of eco-friendly farming material (notice no. 2-4-064) containing tannic acid as new antibacterial-activity against 7 plant bacterial pathogens: Pectobacterium carotovorum subsp. carotovorum (Pcc), Ralstonia solanacearum (Rs), Acidovorax avenae subsp. citrulli (Aac), Xanthomonas cirti pv. citri (Xcc), Erwinia pyrifoliae (Ep), Clavibacter michiganensis subsp. michiganensis (Cmm), and Streptomyces scabies (Sc), Initial screening of antibacterial effects of eco-friendly farming material was performed using the paper disk diffusion method and co-cultivation in broth culture. Tannic acid based eco-friendly farming material showed inhibitory effect against Pcc, Rs, Aac, Xcc, Cmm, and Ss, whereas it did not show inhibition zone against Ep. However, when it tested by co-cultivation in broth culture, it showed strong inhibition effect against all pathogens that declined growth curve compared to bacterial pathogen only. Interestingly, when we observed morphological changes on those pathogens by SEM, cell morphologies of 7 pathogens were slightly changed that seem to be malfunction in their cell envelope.

• Journal of Food Hygiene and Safety
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• v.35 no.5
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• pp.419-429
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• 2020

The problems caused by foodborne pathogens are not only a concern to the food industry but also with regard to global public health. Over the years, fermentation technology has proved to be one of the cheapest and safest methods for inactivating and controlling pathogenic microorganisms in food. Scientific evidence shows that lactic acid bacteria fermentation exerts significant antimicrobial effect against pathogenic bacteria and viruses. Lactic acid bacteria metabolites such as organic acids, bacteriocins and hydrogen peroxides have adverse effects on foodborne pathogens which lead to their inhibition. These compounds do not only cause physical injuries, but also have significant effects on the pathogens' gene expression. Furthermore, the presence of lactic acid bacteria in food provides nutritional competition among foodborne pathogens, and all these factors together suppress their growth. This study reviews our current knowledge of the antimicrobial abilities of lactic acid bacteria, their molecular mechanisms, and their application for inactivating foodborne pathogens.

• The Plant Pathology Journal
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• v.29 no.2
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• pp.136-143
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• 2013

Microbial communities that are associated with plant roots are highly diverse and harbor tens of thousands of species. This so-called microbiome controls plant health through several mechanisms including the suppression of infectious diseases, which is especially prominent in disease suppressive soils. The mechanisms implicated in disease suppression include competition for nutrients, antibiosis, and induced systemic resistance (ISR). For many biological control agents ISR has been recognized as the mechanism that at least partly explains disease suppression. Implications of ISR on recruitment and functioning of the rhizosphere microbiome are discussed.

• Journal of Environmental Science International
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• v.28 no.2
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• pp.225-233
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• 2019

In this study, we investigated the in vitro anti-biofilm activities of plant extracts of chives (Allium tuberosum), garlic (Allium sativum), and radish (Raphanus sativus L.) against environment harmful bacteria (gram-positive Staphylococcus aureus and, gram-negative Salmonella typhimurium and Escherichia coli O157:H7). In the paper disc assay, garlic extracts exhibited the highest anti-biofilm activity. The Minimal Inhibitory Concentration (MIC) of all plant extracts was generally higher for gram-negative bacteria than it was for gram-positive bacteria. Gram-negative bacteria were more resistant to plant extracts. The tetrazolium dye (XTT) assay revealed that, each plant extract exhibited a different anti-biofilm activity at the MIC value depending on the pathogen involved. Among the plant extracts tested, garlic extracts (fresh juice and powder) effectively reduced the metabolic activity of the cells of food-poisoning bacteria in biofilms. These anti-biofilm activities were consistent with the results obtained through light microscopic observation. Though the garlic extract reduced biofilm formation for all pathogens tested, to elucidate whether this reduction was due to antimicrobial effects or anti-biofilm effects, we counted the colony forming units of pathogens in the presence of the garlic extract and a control antimicrobial drug. The garlic extract inhibited the E. coli O157:H7 biofilm effectively compared to the control antimicrobial drug ciprofloxacin; however, it did not inhibit S. aureus biofilm significantly compared to ciprofloxacin. In conclusion, garlic extracts could be used as natural food preservatives to prevent the growth of foodborne pathogens and elongater the shelf life of processed foods.

• Research in Plant Disease
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• v.25 no.2
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• pp.49-61
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• 2019

Plant viruses are among the important pathogens that cause severe crop losses. The most efficient method to control viral diseases is currently to use virus resistant crops. In order to develop the virus resistant crops, a detailed understanding of the molecular interactions between viral and host proteins is necessary. Recessive resistance to a pathogen can be conferred when plant genes essential in the life cycle of a pathogens are deficient, while dominant resistance is mediated by host resistance (R) genes specifically interacting with effector proteins of pathogens. Thus, recessive resistance usually works more stably and broadly than dominant resistance. While most of the recessive resistance genes have so far been identified by forward genetic approaches, recent advances in genome editing technologies including CRISPR/Cas9 have increased interest in using these technologies as reverse genetic tools to engineer plant genes to confer recessive resistance. This review summarizes currently identified recessive resistance genes and introduces reverse genetic approaches to identify host interacting partner proteins of viral proteins and to evaluate the identified genes as genetic resources of recessive resistance. We further discuss recent advances in various precise genome editing technologies and how to apply these technologies to engineer plant immunity.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 1999.04a
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• pp.2-3
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• 1999