• Proceedings of the Microbiological Society of Korea Conference
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• 2007.05a
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• pp.127-127
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• 2007

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.134-134
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• 2017

Recently, host-induced gene silencing (HIGS) system has been successfully applied into development of resistant crops against insects, fungal and viral pathogens. To test HIGS-mediated resistance in rice against rice blast fungus, Magnaporthe oryzae, we first tested possibility of movement of small non-coding RNA from rice cells to rice blast fungus. The rice blast fungus expressing GFP transgene were inoculated to transgenic rice plants ectopically expressing dsRNAi construct targeting fungal GFP gene. Expression of dsRNAi construct for GFP gene in transgenic plants significantly suppressed GFP expression in infected fungal cells indicating that small RNAs generated in plant cells can move into infected fungal cells and efficiently suppress the expression of fungal GFP gene. Consistent with these results, expression of dsRNAi constructs against 3 fungal pathogenic genes of M. oryzae in transgenic rice specifically and efficiently suppressed not only the expression of fungal pathogenic genes, but also fungal infection. The conidia of M. oryzae applied on leaf sheath of transgenic rice expressing dsRNAs against 3 fungal pathogenic genes showed abnormal development of primary hyphae and malfunction of appressorium, which is consistent with the phenotypes of corresponding fungal knock-out mutants. Taken these results together, here, we suggest a novel strategy for development of antifungal crops by means of HIGS system.

• Journal of Forest and Environmental Science
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• v.34 no.5
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• pp.395-404
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• 2018

Since the mass mortality of Quercus mongolica has been first reported in Gyeonggi province at 2004, the disease spread rapidly over Korean peninsula annually. Ambrosia beetle (Platypus koryoensis) was known as the insect vector of oak wilt fungus, Raffaelea quercus-mongolicae, and control methods of the disease had mainly been focused on eradication of insect vector. However, for the efficient management of the disease, combined control methods for both of the pathogenic fungus and insect vector are strongly required. As one of the efforts to suppress the pathogenic fungus, antifungal activities of Streptomyces isolated from oak forest soil were assayed in this study. Optimum culture condition for the selected isolates was also studied, As a result, Streptomyces blastmyceticus cultured in PDB (Potato Dextrose Broth) at $25^{\circ}C$ for 1 week showed the strongest antifungal activity against oak wilt fungus. Mycelial growth inhibition rates (MGIRs) of Streptomyces isolates were compared on culture media supplemented with heated and unheated culture filtrates of S. blastmyceticus. MGIRs on culture media with unheated culture filtrates were generally higher than those on culture media with heated culture filtrates. Antagonistic mechanism to get involved in the inhibition of hyphal growth and spore formation of the pathogen is due to the antifungal metabolites produced by Streptomyces. This study will provide the fundamental information in developing biocontrol agents for the environment-friendly management of oak wilt disease.

• The Plant Pathology Journal
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• v.30 no.4
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• pp.432-436
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• 2014

The soil-borne ascomycete fungus Cylindrocarpon destructans causes ginseng root rot disease and produces various secondary metabolites such as brefeldin A and radicicol. The slow growth of this fungus compared with other plant pathogenic and saprophytic fungi in soil disturbs isolation of this fungus from soil and infected ginseng. In this study, we developed a selective medium for C. destructans using radicicol produced by this fungus. Supplementing 50 mg/L of radicicol to medium inhibited the mycelia growth of other fungi including Botrytis cinerea, Rhizoctonia solani and Alternaria panax, but did not affect the growth of C. destructans. In addition, conidia germination of other fungal species except for C. destructans was inhibited in submerged culture supplemented with radicicol. This medium provides a very efficient tool for isolating C. destructans and also can be used as an enrichment medium for this fungus.

• The Plant Pathology Journal
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• v.16 no.3
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• pp.137-141
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• 2000

A causal fungus of turfgrass blight was isolated from the infected leaves of zoysiagrass (Zoysia japonica Steud.) and identified as Nigrospora sphaerica (Sacc.) Mason by using a light misroscope. Its conidia are large (14-20 ${\mu}{\textrm}{m}$ diameter), shiny, black, aseptate, and smooth-walled spheres. The fungus caused typical blighting symptoms on the two turfgrass plants of bermudagrass (Cynodon dactylon (L.) Pers.) and bentgrass (Agrostis palustris Huds.). The fungus was found to produce a phytotoxic subtance to be associated with the pathogenic mechanism. A phytotoxin was isolated from the liquid cultures of N. sphaerica by repeated silica gel column chromatography and its structure was determined to be 5, 6-dihydro-5-hydroxy-6-propenyl-2H-pyr-2-one (T-3 compound). It was not a host-specific toxin showing phytotoxic effects to various plants inclusing turfgrasses in the leaf-wounding assay, the whole plant test, and the cellular leakage test. The compound caused leaf tip dieback symptoms in turfgrass plants similar to those caused by the pathogen. Thus, T-3 compound is thought to be involved in the development of Nigrospora blight.

• Analytical Science and Technology
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• v.9 no.1
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• pp.107-111
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• 1996

A phytotoxic compound was isolated from a culture of Bipolaris cynodontis, a fungus pathogenic to Bermuda grass. The structure was determined by spectroscopic analyses including 2D NMR experiments, to be sesquiterpene having a 9-carbon unit side chain. The compound inhibits the root growth of the seedlings of Italian ryegrass and rice plant, the host plant of the B. cynodontis, by about 100% at 100ppm, and it is suggested that this may play an important role in the expression of the disease symptom.

• The Plant Pathology Journal
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• v.17 no.5
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• pp.311-314
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• 2001

Phytophthora root rot of lettuce, which has not been reported in Korea before, occurred severely in liquid hydroponic culture. The disease occurred in all seasons and was most severe in summer from June to August, showing over 90% infection rate in some farms. A total of 51 isolates collected from various farms were all identified as Phytophthora drechsleri. The fungus showed strong pathogenicity to lettuce and Chinese cabbage, moderate pathogenicity to cucurbits and tomato, and weak pathogenicity to pepper. However, the fungus was not pathogenic to other leafy vegetables namely: chicory, kale, endive, garland chrysanthemum, spinach beet, and perilla. Among 10 species of Phytophtora inoculated to lettuce, only P. drechsleri and P. cryptogea were found pathogenic.

• Journal of the Korean Wood Science and Technology
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• v.51 no.2
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• pp.145-156
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• 2023

Many skin diseases are caused by microbial infections. Representative pathogenic fungus and bacterium that cause skin diseases are Candida albicans and Staphylococcus aureus, respectively. Malassezia pachydermatis is a fungus that causes animal skin diseases. In this study, we propose a method for removing pathogenic microorganisms from the skin using relatively safe edible herbal extracts. Herbal extracts were screened for skin health through the removal of pathogenic microorganisms, and combinations for effective utilization of the screened extracts were identified. In this study, among methanol extracts of 240 edible plants, C. albicans, S. aureus, and M. pachydermatis were killed by extracts of 10 plants: Acori Gramineri Rhizoma, Angelicae Tenuissimae Radix, Cinnamomi Cortex, Cinnamomi Ramulus, Impatientis Semen, Magnoliae Cortex, Moutan Cortex Radicis, Phellodendri Cortex, Scutellariae Radix, and Syzygii Flos. By evaluating the synergistic antifungal activities against C. albicans using all 45 possible combinations of these 10 extracts, five new synergistic antifungal combinations, Acori Gramineri Rhizoma with Magnoliae Cortex extracts, Acori Gramineri Rhizoma with Phellodendri Cortex extracts, Angelicae Tenuissimae Radix with Magnoliae Cortex extracts, Magnoliae Cortex with Phellodendri Cortex extracts, and Phellodendri Cortex with Syzygii Flos extracts, were identified. By utilizing the selected extracts and five combinations with synergistic antifungal effects, this work provides materials and methods to develop new and safe methods for treating candidiasis using natural products.

• The Plant Pathology Journal
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• v.17 no.6
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• pp.376.2-376
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• 2001

• Food Science and Preservation
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• v.10 no.2
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• pp.241-245
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• 2003

To develope tea-fungus beverage(TB), media added various kinds of ingredients including black tea, persimmon leave tea, pine needle, mugwort mycelia and fruiting body of Cordyceps spp. were prepared fur fermentation. Tea-fungus beverage(TB) was prepared with tea-fungus by fermentation for 2 weeks at 30 $^{\circ}C$. Functional properties of antibacterial activity, electron donating ability and nitrite scavenging ability were investigated in tea-fungus beverage(TB) and 5 times diluted tea-fungus beverage(DTB). Antibacterial activity against pathogenic E. coli and S. aureus was excellent in TB added pine needle, mycelia and fruiting body of Cordyceps japonioa while no activity in TB added persimmon leave tea. Electron donating ability of TB were ranged from 41％ to 87% in TB and were ranged from 11% to 63％ in DFB, high ability was in TB and DTB added pine needle and persimmon leave tea, while low ability in FB and DTB added mycelia and fruiting body of C. militaris. Nitrite scavenging ability was 63% in TB added black tea and 44% in TB added persimmon leave tea. Other ingredients added TB had weak nitrite scavenging ability.