• Mycobiology
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• 제35권4호
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• pp.230-234
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• 2007

In order to breed a Cordyceps bassiana isolate that stably forms fruiting body in artificial cultivation, isolates derived from subculturing and single spores were tested through mating. From C. bassiana EFCC 783, three subcultured isolates EFCC 2830, EFCC 2831 and EFCC 2832 were obtained and fourteen single conidial isolates were obtained from these three subcultured isolates. Two different morphological types were found in the fourteen single conidial isolates. One type was able to form synnemata and another type was not able to form synnemata. Since switch of morphological type was not observed despite their continuous subculturing, cross was performed between the two types and the formation of fruiting body was examined. Ascospores were obtained from a selected fruiting body formed by hybrid of the cross. Self-cross and combinational cross of the ascospore-derived isolates generated hybrids that stably produce high quality fruiting body in artificial media.

• Mycobiology
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• 제38권1호
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• pp.13-16
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• 2010

A specimen of Beauveria bassiana was collected from Yang-yang of Gangwon province, Korea in October 2006. Conidial isolates were prepared from the specimen by the dilution method and inoculated in brown rice medium for fruiting body production. After nearly two months incubation for perithecial stromata developed from single isolates as well as from their combinations. They were determined as Cordyceps bassiana by observing the stromatal characters and their conidial structures. This is the first report of the development of C. bassiana from B. bassiana cultures.

• 한국산림과학회지
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• 제96권5호
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• pp.515-519
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• 2007

An imperfect fungus Fusiococcum species was isolated from Quercus dentata. A naturally infected Daimyo oak tree was collected and showed elongate wounds on the stem. The fungal cultures were initially white and cottony, and later turned dark gray. Numerous solitary pycnidia were developed on the medium surface, and typically spherical. Yellowish conidial masses were exuded from pycnidia on the culture plates. Conidial masses were swollen and measured as approximately 100 to $300{\mu}m$ in length. It appeared that conidia were usually held together in globose to oval drops. Conidia were hyaline, single-celled (nonseptate), ellipsoid to fusoid, and measured as approximately $8.0{\times}2.7{\mu}m$. Based on these cultural and morphological characteristics, the fungal isolate was identified as a species of Fusicoccum Corda. To preserve and examine fungal spores exuded from pycnidia on the medium surface, a vapor fixation procedure for scanning electron microscopy was employed in this study. The specimens were exposed to the vapor of 2% (v/v) glutaraldehyde and 2% (w/v) osmium tetroxide each for 2 h. With the vapor fixation we obtained excellent retention of conidial masses in this study. The simple and versatile procedure for demonstrating fungal spores and their exudation from fruiting bodies would facilitate characterization of diverse pathological and environmental isolates as they are in native environments.

• The Plant Pathology Journal
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• 제26권4호
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• pp.313-320
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• 2010

Genetic instability of the rice blast fungus Magnaporthe oryzae has been suggested as a major factor underlying the rapid breakdown of host resistance in the field. However, little information is available on the mechanism of genetic instability. In this study, we assessed the stability of repetitive DNA elements and several key phenotypic traits important for pathogenesis after serially transferring two isolates though rice plants and an artificial medium. Using isolate 70-15, we obtained a total of 176 single-spore isolates from 10 successive rounds of culturing on artificial medium. Another 20 isolates were obtained from germ tubes formed at the basal and apical cells of 10 three-celled conidia. Additionally, 60 isolates were obtained from isolate KJ201 after serial transfers through rice plants and an artificial medium. No apparent differences in phenotypes, including mycelial growth, conidial morphologies, conidiation, conidial germination, appressorium formation, and virulence, or in DNA fingerprints using MGR586, MAGGY, Pot2, LINE, MG-SINE and PWL2 as probes were observed among isolates from the same parent isolate. Southern hybridization and sequence analysis of two avirulence genes, AVR-Pita1 and AVR-Pikm, showed that both genes were also maintained stably during 10 successive generations on medium and plants. However, one reversible loss of restriction fragments was found in the telomere-linked helicase gene (TLH1) family, suggesting some telomere regions may be more unstable than the rest of the genome. Taken together, our results suggest that phenotype and genotype of M. oryzae isolates do not noticeably change, at least up to 10 successive generations on a cultural medium and in host plants.

• 한국균학회지
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• 제39권3호
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• pp.213-216
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• 2011

2007년부터 2010년에 걸쳐 국내 8지역에서 블루베리의 병을 조사한 결과, 청양, 당진, 대전, 제주 지역의 온실에서 재배중인 블루베리의 신초, 잎, 꽃, 열매에서 잿빛곰팡이병 증상이 빈번하게 관찰되었으며, 조사된 다른 지역의 포장에서는 잿빛곰팡이병 증상이 관찰되지 않았다. 조사된 온실내 이 병의 발생율은 1~30%였다. 병반에서는 Botrytis속 균이 분리되었으며, 단포자 분리된 27개 균주의 형태적 및 배양적 특성을 조사한 결과, 모두 Botrytis cinerea로 동정되었다. 병원성 검정을 위하여 선발한 4균주를 4품종의 블루베리잎에 분생포자현탁액으로 인공접종한 결과, 4균주 모두 접종한 블루베리 잎에 자연병반과 유사한 병반을 형성하였다. 국내의 온실재배 블루베리에 발생하는 B. cinerea에 의한 잿빛곰팡이병은 본 연구에 의해 처음으로 보고된다.

• 한국환경농학회지
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• 제36권4호
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• pp.299-305
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• 2017

탄저병이 발생한 자두에서 11개 탄저병균을 순수 분리하여 병원성을 검정한 후 PDA에 접종하여 $25^{\circ}C$에서 7-10일 동안 배양하면서 각 균주의 균사 생장속도, colony의 특징과 색, 포자 형태 및 크기를 관찰하였다. 각 균주의 genomic DNA를 추출하여 rDNA-ITS 영역을 증폭한 다음, PCR을 하여 염기서열을 해독하였다. 각 균주의 배양적 특성, 포자의 형태와 크기 및 염기서열을 NCBI GenBank의 염기서열과 상동성을 비교하여 동정한 결과 6개 균주는 Colletotrichum acutatum으로, 5개 균주는 C. gloeosporioides로 동정되었다.

• The Plant Pathology Journal
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• 제15권3호
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• pp.162-167
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• 1999

Integration of microbial antagonists with fungicides was tried to control the gray mold caused by Botrytis cinerea on pepper in greenhouse conditions and to reduce fungicide uses. All of the selected bacterial antagonists, Bacillus amyloliquefaciens BL3, Paenibacillus polymyxa BL4, and Pseudomonas putida Cha94, completely inhibited the conidial germination of B. cinerea until 30 days after treatment. However, bacterial colonization of pepper phylloplane was poor in BL4, while the other bacterial isolates and the fungal antagonist Trichoderma harzianum TM colonized well on the phylloplane, maintaining the population density of 104-105 cfu/g until 15 days after microbial treatments. Out of 13 kinds of selected fungicides used for gray mold diseases, polyoxin B and BKF 1995 showed the most discriminatory activity on the fungal growth between B. cinerea and TM. TM grew readily on the media containing those fungicides, while B. cinerea showed poor or no mycelial growth on them. The selected fungicides and antagonists alone reduced incidence of gray mold on pepper, showing disease indices of about 2.4 to 3.0, while its was increased up to 4.2 in the untreated control. Alternate treatments with the antagonists and 2-fold diluted fungicides inhibited the disease incidence as much as the antagonists or fungicides alone, and reduced the secondary inoculum more than the single treatments. This suggests that integration of antagonists and fungicides may be an efficient way to reduce fungicide sprays with reliable control efficacy of the disease. However, there was not much difference in the early and mid-term disease progress among the treatments and the untreated control, probably due to extremely favorable environmental conditions for the disease development in this experiment.