• The Plant Pathology Journal
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• 제39권3호
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• pp.275-289
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• 2023

Fungal isolates from infected Chinese quince trees were found to cause black rot in Yeongcheon, Gyeongsangbuk Province, Korea. The quince leaves withered and turned reddish-brown and fruits underwent black mummification. To elucidate the cause of these symptoms, the pathogen was isolated from infected leaf and fruit tissues on potato dextrose agar and Levan media. Several fungal colonies forming a fluffy white or dark gray mycelium and two types of fungi forming an aerial white mycelium, growing widely at the edges, were isolated. Microscopic observations, investigation of fungal growth characteristics on various media, and molecular identification using an internal transcribed spacer, β-tubulin, and translation elongation factor 1-α genes were performed. The fungal pathogens were identified as Diplodia parva and Diplodia crataegicola. Pathogenicity tests revealed that the pathogen-inoculated fruits exhibited a layered pattern, turning brown rotting; leaves showed circular brown necrotic lesions. The developed symptoms were similar to those observed in the field. Fungal pathogens were reisolated to fulfill Koch's postulates. Apples were inoculated with fungal pathogens to investigate the host range. Strong pathogenicity was evident in the fruits, with browning and rotting symptoms 3 days after inoculation. To determine pathogen control, a fungicidal sensitivity test was conducted using four registered fungicides. Thiophanate-methyl, propineb, and tebuconazole inhibited the mycelial growth of pathogens. To the best of our knowledge, this is the first report on the isolation and identification of the fungal pathogens D. parva and D. crataegicola from infected fruits and leaves of Chinese quince, causing black rot disease in Korea.

• Mycobiology
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• 제43권3호
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• pp.366-370
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• 2015

Acanthopanax divaricatus, a member of the Araliaceae family, has been used as an invigorant in traditional Korean medicine. During disease monitoring, a stem with small, irregular, brown lesions was sampled at a farm in Cheonan in 2011. The symptoms seen were sunken cankers and reddish-brown needles on the infected twig. The isolated fungal colonies were whitish, having crenated edges and aerial mycelium on the surface, and with black gregarious fruiting bodies. The reverse plate was creamy white. Conidia were $17{\sim}22{\times}3.5{\sim}4.2{\mu}m$, fusiform, 4-septate, and straight to slightly curved. The nucleotide sequence of the partial translation elongation factor 1 alpha gene of the fungal isolate, shares 99% sequence identity with that of known Pestalotiopsis ellipsospora. Based on the results of the morphological and molecular analyses, the fungal isolate was identified as P. ellipsospora. In Korea, this is the first report of canker on A. divaricatus.

• 아시안잔디학회지
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• 제14권1호
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• pp.241-250
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• 2000

In 1997, a new disease on creeping bentgrass and Kentucky bluegrass occurred in the green and fairway of a few golf courses in Korea. The disease spread gradually throughout the country and became a threat to turfgrass management. Symptoms of the disease consisted of small, circular, and sunken patches sized 3~5cm in diameter. The disease named as a dollar spot following its characteristic symptoms of circular blight and bleach on the green. The disease peaked two times in a year from April to June and from late August to October and white cottony mycelia of the causal fungus developed on diseased turfs in the early morning when the conditions were favored. A causal fungus was consistently isolated from the infected tufgrass and seven isolates originated from seven golf courses located in six provinces were selected for further study. The fungus produced abundant white aerial mycelia on PDA and turned to dark gray or light brown as it aged. Width of the mycelium was ca. $5~8\mu\textrm{m}$. While sclerotia were not readily formed on the medium, scattered small and dark colored stromata were developed on the surface. The fungus grew well on PDA between 5 to $30^{\circ}C$ and maximally around $25^{\circ}C$. Based on investigated mycological and cultural characteristics, the causal agent of dollar spot was identified as Sclerotinia homoeocarpa. The fungus showed strong pathogenicity to several turfs as creeping bentgrass, Kentucky bluegrass, perennial ryegrass, tall fescues, and zoysiagrass.

• 대한의생명과학회지
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• 제23권2호
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• pp.96-103
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• 2017

Nocardia species (spp.) are opportunistic pathogen in immunocompromised hosts. The genus Nocardia contains more than 70 species. Nocardia takedensis has been recently reported as a new species of the genus Nocardia. In this study, we describes the first clinical isolate of N. takedensis from the skin lesion in Busan, Korea. For the identification of clinical isolate to the species level as N. takedensis, classical methods (colony morphology, biochemical characteristics, and antimicrobial susceptibility), molecular method (16S rRNA gene sequencing), and MS (mass spectrometry) analysis were conducted. Clinical isolates grew slowly on the culture media (5% sheep blood agar and chocolate agar) under 5% $CO_2$ condition. Especially, carotene pigmentation was detected well on the media. Using mass spectrometry, Nocardia isolate was not identified to the species level. However, molecular method based on 16S rRNA sequencing confirmed the isolate as N. takedensis correctly. N. takedensis isolate was partial positive for acid-fast bacilli on the Ziehl-Neelsen method. And it was observed to be resistance to amoxicillin/clavulanic acid and ciprofloxacin. Our results provide useful information to develop optimal identification protocol of N. takedensis in clinical diagnostic laboratories.

• The Plant Pathology Journal
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• 제18권3호
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• pp.161-164
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• 2002

Colletotrichum musae was isolated from dark-brown anthracnose lesions on commercial banana (Musa sapientum L.) to establish the causal agent of the symptom. The fungus grew fast and produced white aerial mycelium on PDA. Acervuli developed abundantly on culture plates after incubation for 10 days at $25^{\circ}C$. Pinkish conidial masses were produced on the acervuli, which mostly coalesced together, Conidia were aseptate, hyaline, straight, ellipsoid to globose, and 14.5$\times$6.9 $\mu\textrm{m}$ in size. Black, clavate, round, or irregular-shaped appressoria measuring 8.8$\times$6.8 $\mu\textrm{m}$ were readily formed from germ tubes. Setae-like structures were not found either on the lesion or on the cultures. Sclerotia were also absent. Among the media, PDA medium was the best for mycelial growth. The optimum temperature for mycelial growth was $28^{\circ}C$, while the optimum pH ranged from pH 5.5 to 6.5. The isolates of C musae caused black necrotic lesions on banana fruits by needle-wound inoculation, and orange-colored spore masses were produced on the lesions. The fungus also caused discoloration on apple fruits inoculated.

• 식물병연구
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• 제22권2호
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• pp.111-115
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• 2016

Wilt disease appeared the first in greenhouse-grown safflower (Carthamus tinctorius) in Jeonju, Korea. With the advancement of the disease, the infected plants were withered and died. In order to investigate the causal organism of this symptom disease, fungus was isolated from the infected plants and cultured on potato dextrose agar medium. The fungus showed the white or orange colony color with aerial mycelium. Macroconidia were from falcate to straight, usually 3-5 septate with $38.0-66.7{\times}2.9-4.4{\mu}m$. The fungus was inoculated to a new safflower plant and caused the same wilt. With morphological characters and pathogenicity results, sequence analyses (internal transcribed spacer ribosomal DNA and translation elongation factor $1{\alpha}$) suggested that, the isolated fungus is Fusarium proliferatum. This is the first report of Fusarium wilt disease caused by F. proliferatum on safflower in Korea.

• 한국균학회지
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• 제48권1호
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• pp.39-45
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• 2020

A fungal isolate US-18-11 was isolated from the soil in Uiseong, Korea. The mycelium growth measured after 7 days of incubation at 22℃ on malt extract agar (MEA) and oatmeal agar (OA) media was 42-43 mm and 41-44 mm in diameter, respectively. The fungal colony formed white to dull green aerial mycelia that were floccose with regular margins and olivaceous black with leaden gray patches on the reverse side. The conidia were hyaline to brown in color, ellipsoidal to ovoid, guttulate, abundant, globose, solitary, or confluent measuring 3.2-7.2×1.1-2.3 ㎛. A BLAST search of the large subunit (LSU), internal transcribed spacer (ITS) region, second largest subunit of DNA-directed RNA polymerase II (RPB2) and β-tubulin (TUB2) gene sequences revealed that the isolate US-18-11 has similarities of 99, 100, 97, and 99% with those of Epicoccum draconis CBS 186.83, respectively. A neighbor-joining phylogenetic tree constructed based on the concatenated dataset of above-mentioned sequences showed that isolate US-18-11 clustered with Epicoccum draconis CBS 186.83 in the same clade. Based on the results of morphological, cultural, and phylogenetic analysis, the isolate US-18-11 was identical to the previously described E. draconis CBS 186.83. To our knowledge, this is the first report of E. draconis in Korea.

• 한국미생물·생명공학회지
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• 제33권2호
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• pp.90-95
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• 2005

An Actinomycetes producing an anti-VRSA (vancomycin-resistant Staphylococcus aureus) substance was isolated from soil. The cultural, morphological, physiological and phylogenetic analyses of an isolated strain were investigated for identification. Cultural characteristics based on ISP (International Streptomyces Project) were as follows: white aerial mycelium, yellow reverse side, and good growth on various medium. Also, the isolate did not produce the soluble pigment. Morphological characteristics were showed cylindrical spore chain and smooth spore surface by SEM (Scanning Electron Microscope). Physiological characteristics were showed LL-type by DAP isomer analysis and detected glycine, glutamic acid and alanine. A phylogenetic analysis of the 16S rDNA provided a clue that the isolated strain was actually a member of the genus Streptomyces, because the determined sequence exhibited a higher homology with Streptomyces echinatus. The isolate was identified to be a genus of Streptomyces sp.. The optimal culture conditions for the maximum production of anti-VRSA substance by Streptomyces sp. were attained in a culture medium composed of $2.0\%$ (w/v) glucose, and $0.4\%$ (w/v) yeast extract. The anti-VRSA substance was highly produced after 5 days of culture. Optimal pH and temperature conditions for the production of anti-VRSA substance were pH 7.0 and $28^{\circ}C$, respectively.

• 식물병연구
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• 제11권1호
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• pp.77-79
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• 2005

2002년 전북지방에 야생하는 칡의 잎에 잎마름병이 발생하였다. 병징은 잎과 어린 줄기에 발생하고 잎에 처음에는 수침상 병반이 나타나고 잎의 가장자리 부분부터 갈색을 띠면서 안쪽으로 말라 들러가기 시작하였다. 병이 진전되면 잎과 어린 줄기는 갈변하며 낙엽 되었다. 병원균은 PDA에서 기중균사를 형성하고, 처음에는 흰색을 띠다가 연한 갈색으로 변하였다. 균사는 $90^{\circ}$로 분지하고, 대부분 하난의 세포에 다핵을 형성하였다. 또한 PDA에서 부정형 또는 타원형으로 0.5~3.0mm의 균핵을 형성하였다. 본 연구에서 칡의 잎에 마름병을 일으키는 병원균의 균학적 특징 및 형태적 특징을 조사한 결과, Rhizoctonia solani Kuhn에 의한 칡 잎마름병으로 명명하고자 제안한다.

• 식물병연구
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• 제24권4호
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• pp.321-327
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• 2018

2018년 경북 영천지역 사과과수원에서 미이라화 된 과실, 배꼽이 썩어 들어간 과실과 점무늬를 형성한 과실의 증상을 관찰하였다. 이 증상의 원인균을 증명하기 위해 이병체에서 균사체를 분리하여 병원성 검정을 수행한 결과 건전한 사과 과실이 급격히 썩으면서 발견 시의 병징과 일치하였다. 곰팡이의 특성은 흰색의 균사로 자라다가 시간이 지나면서 암회색으로 변하였다. 병자각 안에서 분생포자가 형성되고 분생포자는 갈색의 타원 형태였으며 격막이 없고 끝이 둥근 형태이다. 분생포자 크기는 $21.7-28.3{\times}9.9-15.3{\mu}m$이다. 병원균의 ITS, ${\beta}$-tubulin 유전자의 염기서열을 이용하여 유연관계를 분석한 결과 Diplodia seriata로 동정되었다. Diplodia seriata는 국내에서 식물병원균으로 보고된 바 없다. 사과에서 Diplodia seriata에 의한 Black rot은 우리나라에서 처음 보고되는 것이며 사과 검은썩음병으로 명명하여 보고하고자 한다.