• The Plant Pathology Journal
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• v.28 no.3
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• pp.317-321
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• 2012

Plants are the promising reservoirs for natural products with their diverse secondary metabolites. Many invasive plants have been introduced in Korea, which adversely affect on the native ecosystem but holds difficulty removing them due to their proliferation. In this study, we evaluated disease control efficacy of methanol extracts from four invasive plant species against 7 representative crop pathogens. Methanol extract of Phytolacca americana effectively suppressed rice blast, tomato gray mold, and tomato late blight in a dose dependent manner. The methanol extract of Amorpha fruticosa also exhibited potent antifungal activity against pepper anthracnose in a concentration dependent way. These data suggest that the extracts of P. americana and A. fruticosa can be developed as plant disease protection agents against rice blast, tomato gray mold, tomato late blight, and pepper anthracnose. Furthermore, more extensive research will be required to identify and isolate active compounds from problematic invasive plant species to develop valuable agrochemicals.

• Journal of Microbiology and Biotechnology
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• v.18 no.2
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• pp.234-241
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• 2008

Agrobacterum tumefaciens-mediated transformation (ATMT) is becoming an effective system as an insertional mutagenesis tool in filamentous fungi. We developed and optimized ATMT for two Colletotrichum species, C. falcatum and C. acutatum, which are the causal agents of sugarcane red rot and pepper anthracnose, respectively. A. tumefaciens strain SK1044, carrying a hygromycin phosphotransferase gene (hph) and a green fluorescent protein (GFP) gene, was used to transform the conidia of these two Colletotrichum species. Transformation efficiency was correlated with co-cultivation time and bacterial cell concentration and was higher in C. falcatum than in C. acutatum. Southern blot analysis indicated that about 65% of the transformants had a single copy of the T-DNA in both C. falcatum and C. acutatum and that T-DNA integrated randomly in both fungal genomes. T-DNA insertions were identified in transformants through thermal asymmetrical interlaced PCR (TAIL-PCR) followed by sequencing. Our results suggested that ATMT can be used as a molecular tool to identify and characterize pathogenicity-related genes in these two economically important Colletotrichum species.

• The Plant Pathology Journal
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• v.38 no.6
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• pp.593-602
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• 2022

Anthracnose, caused by the ascomycete fungus Colletotrichum scovillei, is a destructive disease in pepper. The fungus germinates and develops an infection structure called an appressorium on the plant surface. Several signaling cascades, including cAMP-mediated signaling and mitogen-activated protein kinase (MAPK) cascades, are involved in fungal development and pathogenicity in plant pathogenic fungi, but this has not been well studied in the fruit-infecting fungus C. scovillei. Ste50 is an adaptor protein interacting with multiple upstream components to activate the MAPK cascades. Here, we characterized the CsSTE50 gene of C. scovillei, a homolog of Magnaporthe oryzae MST50 that functions in MAPK cascades, by gene knockout. The knockout mutant ΔCsste50 had pleiotropic phenotypes in development and pathogenicity. Compared with the wild-type, the mutants grew faster and produced more conidia on regular agar but were more sensitive to osmotic stress. On artificial and plant surfaces, the conidia of the mutant showed significantly reduced germination and failed to form appressoria. The mutant was completely non-pathogenic on pepper fruits with or without wounds, indicating that pre-penetration and invasive growth were both defective in the mutant. Our results show that the adaptor protein CsSTE50 plays a role in vegetative growth, conidiation, germination, appressorium formation, and pathogenicity in C. scovillei.

• Horticultural Science & Technology
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• v.30 no.2
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• pp.185-191
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• 2012

For initiation of resistance breeding program of the red pepper, 21 PR ($Phytophthora$ resistance) cultivars, 36 cultivars collected from USA and 'Supermanitta' which is a susceptible cultivar against phytophthora blight were assayed against phytophthora blight, powdery mildew, and anthracnose. For seedling assay of phytophthora blight, three different mating type strains of $Phytophthora$ $capsici$ were used (A1, A2, Sterile). The result showed that most of the pepper of PR cultivars were resistance or moderately resistance at each mating type. 'Yeokganghongjanggun' was resistant to all three $P.$ $capsici$ strains and 'PR-Datta' and 'PR-Manitta' were resistant or moderately resistant at each type. In case of the collected cultivars, 'NuMex J.E.Parker', 'Omni Color', and 'SCM334' were resistant to all the three types and some cultivars including 'Sweet Banana' and 'Tabasco' were moderately resistant to each type fungi. 'Orange Habanero' and 'Black Cuban' were resistant to powdery mildew and 'Supermanitta' and 'PR Keumdong' were moderately resistant, while 'Santa Fe Grande', 'NuMex Pinata' and 'Puya' were very susceptible. In the case of anthracnose, 'Aji Limon' and 'Capsicum baccatum var. pendulum 3-4' were resistant and 'Pobalno', 'Omni Color', 'Negro', 'Mesilla', 'Mulato', 'Bhut Jolokia', 'Big Dipper', 'Black Cuban', 'NuMex Pinata', and 'NuMex Big Jim' were moderately resistant. The most PR cultivars except 'Taesan' were susceptible or very susceptible. These resistant individuals identified through this experiment can be used as sources of resistance to pepper pathogens in the future breeding programs.

• Korean Journal of Microbiology
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• v.49 no.2
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• pp.195-199
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• 2013

A bacterial strain MPL-01 was isolated from the large intestine of a wild boar. The strain was shown to have morphological, physiological and biochemical characteristics, fatty acids composition typical of Bacillus. The 16S rRNA gene sequence showed that the isolate formed distinct phyletic line that was most closely related to this of Bacillus atrophaeus (99.99%). It was proposed that the strain is classified as B. atrophaeus MPL-01. The strain MPL-01 exhibited the strongest antifungal activity against Colletotrichum acutatum, the pathogen of anthracnose of chili peppers. The ethyl acetate extract of culture filtrate possessed not only the antifungal activity but also the bio-surfactant activity. Therefore, the strain MPL-01 could be a useful bacterium in the development of bio-control process against the pathogenic fungi.

• The Plant Pathology Journal
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• v.25 no.3
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• pp.205-212
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• 2009

Colletotrichum acutatum was the main cause of the recent outbreaks of anthracnose on pepper fruit in Korea. To facilitate molecular analysis of C. acutatum, we generated an arginine auxotrophic mutant of the C acutatum strain JC24 using a targeted gene replacement strategy. A 3.3-kb genomic region carrying an ortholog (designated CaARG2) of the fungal gene encoding N-acetylglutamate synthase, the first enzyme of arginine biosynthesis in fungi, was deleted from the fungal genome. The mutant exhibited normal growth only when arginine was exogenously supplied into the culture medium. Transformation of the arginine auxotrophic mutant with a plasmid DNA carrying an intact copy of CaARG2, which was smaller than the deleted region in the mutant, not only caused random vector insertions in the fungal genome, but also recovered both hyphal growth and pathogenicity of the mutant to the wild-type level. Using this new selection system, we have successfully developed a restriction enzyme-mediated integration procedure, which would provide an economically efficient random mutagenesis method in C. acutatum.

• Journal of Applied Biological Chemistry
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• v.60 no.3
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• pp.265-269
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• 2017

Environment-friendly, commercially-available agricultural products were investigated for antimicrobial activity against Sclerotinia sclerotiorum, as a pathogen of sclerotium disease. Then ${\beta}$-thujaplicin from Chamaecyparis obtuse was investigated for antifungal activity against six kinds of pathogenic fungi. It showed a statistically significant (p <0.001) growth inhibition effect on Sclerotinia sclerotiorum as a pathogen of sclerotium disease, Rhizoctonia solani AG-4 as a pathogen of damping off, Phytophthora capsici as a pathogen of phytophthora blight, and Colletotrichum coccodes as a pathogen of anthracnose at a concentration of 50 ppm and on Stemphylium solani as a pathogen of spotting disease and Alternaria alternata as a pathogen of black mold at a concentration of 100 ppm. In conclusion, these results indicate that it may be possible to develop environment-friendly agricultural products using ${\beta}$-thujaplicin compounds.

• The Korean Journal of Pesticide Science
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• v.10 no.4
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• pp.249-261
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• 2006

Fifty compounds such as ester, sulfonyl ester, carbamate, ether and phosphoyl ester derivatives of 4-isopropyl-3-methylphenol(I) and 5-isopropyl-3-methylphenol(II) were synthesized. These derivatives were identified by IR, GC/MS and $^1H$-NMR spectra. Their in vitro antifungal activities were tested against 10 plant pathogenic fungi. Among them, several compounds showed potent in vitro antifungal activity. The selected compounds showing potent in vitro antifungal activity were tested for their in vivo antifungal activities against 5 plant diseases such as rice blast, rice sheath blast, cucumber anthracnose, cucumber gray mold and tomato late blight. As a result, 4-isopropyl-3-methylphenyl(2-amino-thiazole-4-yl)methoxyiminoacetate(I-7a) showed a potent in vivo antifungal activity against rice blast. Both methyl (4-isopropyl-3-methylphenoxy)acetate(I-4d) and methyl (5-isopropyl-3-methylphenoxy)acetate(II-4d) effectively inhibited the development of cucumber gray mold.

• Korean Journal of Environmental Agriculture
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• v.37 no.1
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• pp.34-40
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• 2018

BACKGROUND: In order to select a fungicide that can effectively control anthracnose disease in Japanese plum fruit, mycelial growth inhibition effect and spore germination inhibition effect of six fungicides were tested in vitro against six isolates of Colletotrichum acutatum and five isolates of C. gloeosporioides that were isolated from diseased Japanese plum fruit. METHODS AND RESULTS: Inhibitory effects of fungicides on mycelial growth were investigated after inoculating each isolate on potato dextrose agar amended with four discriminatory concentrations of each fungicide for 7 days at $25^{\circ}C$. For spore germination inhibitory effect, each isolate of the Colletotrichum spp. was cultured in potato dextrose agar for 7-14 days at $25^{\circ}C$. After adjusting the concentration of spores of each isolate to $1{\times}10^6mL^{-1}$ by diluting with 0.025% PDB, the spore suspension was mixed with each fungicide (1:4, v/v), and $60{\mu}L$ aliquots were dispensed to sterile hole slide glass. Hole slide glasses were placed in a humidified box and incubated for 15 hours at $25^{\circ}C$. Then, spore germination was observed under an optical microscope. At recommended concentration of fungicide prochloraz manganese showed the highest mycelial growth inhibitory effect and dithianon showed the lowest mycelial growth inhibition. The $EC_{50}$ values for the inhibition of spore germination by dithianon and pyraclostrobin were $0.069-0.126{\mu}g/mL$ and $0.37-1.59{\mu}g/mL$, respectively. Although benomyl, prochloraz manganese, azoxystrobin, and tebuconazole did not inhibit the spore germination, they appeared to restrain mycelial growth by abnormal growth of germ tube and mycelium after germination. CONCLUSION: Dithianon seemed to have preventive effect. Prochloraz manganese, azoxystrobin, and tebuconazole were likely to have control effect. Pyraclostrobin is considered to have both preventive and control effect against anthracnose disease of Japanese plum fruit.

• Research in Plant Disease
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• v.13 no.2
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• pp.110-114
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• 2007

Anthracnose fungus was most pathogenic on soybean sprout, of the fungi and bacteria isolated from rotten sprout on market. Bacterial strains associated were not virulent. Dry heat (DHT) applied even as high as $65^{\circ}C$ for 30min. was not effective enough to eliminate the artificially inoculated Colletotrichum gloeosporioides propagules from seedllots. Hot water immersion treatment (HWT), at elevated temperature of $55^{\circ}C$ for 20 min, did eliminate the pathogen but reduced seed germinating and retarded sprout growth: Seed germination was practically acceptable when the seedlots were exposed to at $55^{\circ}C$ for 5 min, but about 20% anthracnose propagules survived. Accordingly, we have optimized the HWT scheme for 5 min at $60^{\circ}C$. This scheme was validated, at small to large scale production system, that surely rule out the possible carry over of the bacterial contaminant from seedlots. This result should improve the shelf-life of soybean sprout on the market.