• 한국균학회소식:학술대회논문집
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• 2018.05a
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• pp.44-44
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• 2018

Fusarium head blight (FHB) caused by infection with Fusarium graminearum leads to enormous losses to crop growers, and may contaminate grains with a number of Fusarium mycotoxins that pose serious risks to human and animal health. Antagonistic bacteria that are used to prevent FHB offer attractive alternatives or supplements to synthetic fungicides for controlling FHB without the negative effects of chemical management. Out of 500 bacterial strains isolated from soil, Bacillus amyloliquefaciens JCK-12 showed strong antifungal activity and was considered a potential source for control strategies to reduce FHB. B. amyloliquefaciens JCK-12 produces several cyclic lipopeptides (CLPs) including iturin A, fengycin, and surfactin. Iturin A inhibits spore germination of F. graminearum. Fengycin or surfactin alone did not display any inhibitory activity against spore germination at concentrations less than 30 ug/ml, but a mixture of iturin A, fengycin, and surfactin showed a remarkable synergistic inhibitory effect on F. graminearum spore germination. The fermentation broth and formulation of B. amyloliquefaciens JCK-12 strain reduced the disease incidence of FHB in wheat. Furthermore, co-application of B. amyloliquefaciens JCK-12 and chemical fungicides resulted in synergistic in vitro antifungal effects and significant disease control efficacy against FHB under greenhouse and field conditions, suggesting that B. amyloliquefaciens JCK-12 has a strong chemosensitizing effect. The synergistic antifungal effect of B. amyloliquefaciens JCK-12 and chemical fungicides in combination may result from the cell wall damage and altered cell membrane permeability in the phytopathogenic fungi caused by the CLP mixtures and subsequent increased sensitivity of F. graminearum to fungicides. In addition, B. amyloliquefaciens JCK-12 showed the potential to reduce trichothecenes mycotoxin production. The results of this study indicate that B. amyloliquefaciens JCK-12 could be used as an available biocontrol agent or as a chemosensitizer to chemical fungicides for controlling FHB disease and as a strategy for preventing the contamination of harvested crops with mycotoxins.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.123.2-124
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• 2003

Fusarium graminearum (telomorph：Gibberella zeae), an important fungal pathogen of cereal crops with ubiquitous geographic distribution, produces mycotoxins on diseased crops that has threaten human and animal health. Recently severe epidemics of scab diseases of barley and rice by this fungus occurred in Korea, causing serious economic losses. To determine genetic diversity of F. graminearum from rice in Korea, a total of 269 isolates were obtained from Southern part of Korea during 2001-2002. A phylogenetic tree of the isolates was constructed by using amplified fragment length polymorphism (AFLP). Population structure of the rice isolates consists of a single lineage (lineage 6). Frequency of female fertility among these Isolates was relatively low (37％) compared to that among lineage 7 isolates from Korean corn. PCR amplification using chemotype specific primers derived from Tri7 and Tri13 genes at the trichothecene biosynthesis gene cluster revealed that most isolates (260) were NIV chemotype；9 isolates were identified as DON chemotype by Tri13 but as either NIV chemotype or unknown by Tri7. The result of chemical analysis also supported the chemotype determination；all of the NIV chemotype isolates produced NIV, whereas the 9 isolates produce either DON or no toxin.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.85.2-86
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• 2003

Fusarium graminearum is an important pathogen of cereal crops in many areas of the world causing head blight and ear rot of small grains. In addition to serious economic losses, this fungus produces mycotoxins, such as trichothecenes and zearalenone on diseased crops and has been a potential threat to human and animal health. To massively identify pathogenesis-related genes from F. graminearum, two representative strains (SCKO4 from rice and Z03643 from wheat) were mutagenized using restriction enzyme-mediated integration (REMI). In total, 20,DOD REMI transformants have been collected from the two strains. So far, 63 mutants for several traits involved in disease development such as virulence, mycotoxin production, and sporulation have been selected from 3,000 REMI transformants. Now, selected mutants of interest have being genetically analyzed using a newly developed outcross method (See Jungkwan Lee et al poster). In addition, cloning and characterization of genomic DNA regions flanking the insertional site in the genome of the mutants are in progress.

• Research in Plant Disease
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• v.22 no.3
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• pp.145-151
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• 2016

Chemical fungicides have reduced Fusarium head blight (FHB) severity. However, by the effects of fungicide residues, they can only be used up to 30 days before time of harvest. Therefore, the development of new biofungicides that are applicable until harvest is required. In order to select plant extracts having antifungal activity against Fusarium graminearum for the control of FHB, we investigated the inhibitory effects of 225 medicinal plant extracts on spore germination of F. graminearum. Of these plant extracts, the methanol extract of Cirsium japonicum (CJ) roots showed the strongest antifungal activity. Through solvent partitioning, repeated column chromatography, and spore germination bioassay, two chemicals were purified and then their chemical structures were identified as ciryneol C (CC) and 1-heptadecene-11,13-diyne-8,9,10-triol (HD-ol) which are polyacetylene substances. Two active compounds effectively inhibited the germination of F. graminearum macroconidia; HD-ol ($IC_{50}$ of $3.17{\mu}g/ml$) showed stronger spore germination inhibitory activity than that of CC ($IC_{50}$ of $28.14{\mu}g/ml$). In addition, the wettable powder type formulation of ethyl acetate extract of CJ roots suppressed the development of FHB in dose-dependent manner, with control values of 78.92% and 31.56% at 250- and 500-fold dilutions, respectively. Combining these findings suggest that the crude extract of CJ roots containing polyacetylene compounds could be used as botanical fungicide for the control of FHB.

• Korean Journal of Veterinary Research
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• v.32 no.3
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• pp.413-419
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• 1992

Deoxynivalenol producing isolates of Fusarium Graminearum R 6576 was grown on rice for 25 days at 19,25 and $28^{\circ}C$. Maximum production of deoxynivalenol(DON) by Fusarium graminearum R 6575 occurred at $28^{\circ}C$ and 20 days. Maximum concentration of 940 ppm DON were obtained after 20 days at an initial moisture content of 40%. A DON derivative, 15-acetyl-DON (15-ADON), was also found at concentrations of 150~300ppm after 5~10 days. Crude culture extracts were purified by water-saturated silica gel column chromatography which selectivity extracted DON when methylene chloride was as the mobile phase. Purity of crystallized DON was verified by thin layer and high performance liquid chromatography. Also this method was advantage method or production of DON and require little organic sorbent than the other methods.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.99.2-99
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• 2003

An attempt was made to screen antifungal activities of Bacillus thuringiensis strains on various plant pathogens, Botryosphaeria dothidea, Diaporthe actinidiae, Botrytis cinerea, Glomerella cingulata, Colletorichum cocodes, Sclerotinia scierotiorum, Alternaria alternata, Helicobuidium mompa, Bipolaris coicis, Fusarium graminearum and Rhizoctosnia solani. Ten and forty-five strains of B. thuringiensis were isolated from animal feces in Korea and Japan, respectively. Inhibitory effects of the strains on the mycelial growth of the pathogens were examined on the mixed media of potato dextrose agar and nutrient agar. Approximately half of the strains inhibited the mycelial growth of one or more pathogens. Most of the pathogens were inhibited by any of the strains but Fusarium graminearum and Rhizoctonia solani were not inhibited at all. This is the first report that B. thuringiensis shows a potent antifungal activity on plant pathogens in Korea.

• The Plant Pathology Journal
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• v.32 no.5
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• pp.407-413
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• 2016

Fusarium graminearum species complex (FGSC) causes Fusarium head blight in small grain cereals. To date, four species (F. graminearum, F. asiaticum, F. boothii, and F. meridionale ) belonging to FGSC frequently occur in Korean cereals. In addition, we first reported the occurrence of additional species (F. vorosii ) within FGSC, which was isolated from barley, corn, and rice in Korea. Phylogenetic analysis of the Fusarium isolates of this group using combined multigene sequences confirmed species identification. Moreover, the macroconidia produced by these isolates were morphologically similar to those of the F. vorosii holotype. Chemical analysis indicated that the F. vorosii isolates produced various trichothecenes such as nivalenol and deoxynivalenol with their acetyl derivatives along with zearalenone. Pathogenicity tests demonstrated that all of the F. vorosii isolates examined were pathogenic on barley, corn, and rice with variation in aggressiveness. This study is the first report of F. vorosii in Korean cereals, their pathogenicity towards barley and corn, and their ability to produce trichothecenes and zearalenone.

• Proceedings of the Microbiological Society of Korea Conference
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• 2004.05a
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• pp.123-125
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• 2004

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2002.11a
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• pp.92-92
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• 2002

• The Plant Pathology Journal
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• v.31 no.3
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• pp.316-321
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• 2015

A small cationic peptide (JH8944) was tested for activity against a number of pathogens of agricultural crops. JH8944 inhibited conidium growth in most of the tested plant pathogens with a dose of $50{\mu}g/ml$, although one isolate of Fusarium oxysporum was inhibited at $5{\mu}g/ml$ of JH8944. Most conidia of Fusarium graminearum were killed within 6 hours of treatment with $50{\mu}g/ml$ of JH8944. Germinating F. graminearum conidia required $238{\mu}g/ml$ of JH8944 for 90% growth inhibition. The peptide did not cause any damage to tissues surrounding maize leaf punctures when tested at a higher concentration of $250{\mu}g/ml$ even after 3 days. Liposomes consisting of phosphatidylglycerol were susceptible to leakage after treatment with 25 and $50{\mu}g/ml$ of JH8944. These experiments suggest this peptide destroys fungal membrane integrity and could be utilized for control of crop fungal pathogens.