• 한국균학회지
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• 제22권4호
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• pp.332-337
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• 1994

Under standard condition (Han, et al., 1990: glucose 1%-nitrate 0.1% minimal medium, 30 ml in 9 cm plate, $10^6$ cells of inoculum per plate), wild type of Aspergillus nidulans developed both sexual and asexual organs in ballance, while velA1 mutant developed asexual ones preferentially. Increase of glucose concentration did not significantly affect the asexual sporulation. However, development of sexual organs were largely affected. It was greatly enhanced when favorable nitrogen source, for example, casein hydrolysate was added, which is contrary to the case of Neurospora or Saccharomyces where limitation of N source induces sexual development. On most of moderate C sources asexual development in $velA^+$ strain was largely inhibited except acetate on which only asexual spores were produced, while that in velA1 mutant strain was not affected. Lactose promoted the sexual development even in velA1 mutant indicating that lactose itself or its metabolic intermediate may induce sexual development independent of allelic state of velA gene. On other moderate favorable C sources, glycerol, galactose and ethanol, asexual development was largely inhibited in $velA^+$ strain but not in velA1 mutant strain. Sexual organs were, however, never produced on acetate. These results suggested that asexual development of wild type is largely dependent on C sources and the velA gene is involved in the repression of asexual development in not-enough-grown (non-competent) thalli resulting in preferential progression of sexual development.

• 한국균학회지
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• 제8권1호
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• pp.1-5
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• 1980

마디풀 전초(全草)의 건조물인 편축의 열수전탕(熱水煎湯)의 여과액으로 증발 농축시킨 추출액을 만들어 대조인 Sabouraud's dextrose arar 배지에 매지 10ml當 편축 추출액 0.5,1,2 및 3ml를 각각 혼합한 배지로서 T. rubrum, T. mentagrophytes, E. floccccosum 및 M. canis 등 4균종을 각각 3종씩 배양하여 그 발육상태를 관찰하므로서 진균발육억제작용의 유무를 검색하여 다음과 같은 성적을 얻었다. 1. E. floccosum은 편축추출물 3ml 혼합의 평판배지 사면배지 및 현적배양에서 거의 완전히 현지한 균발육억제작용을 인정할 수 있었다. 2. T. menagrophytes, T. rubum 및 M. cains에 대해서는 부분적으로 현저한 억제자용과 발육균태(菌苔)의 크기로 보아 반이불(半以不)의 크기로 발육이 억제되는 증정도의 억제효과를 인정하였다.

• Journal of Microbiology and Biotechnology
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• 제17권4호
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• pp.547-559
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• 2007

Bacillus thuringiensis (Bt) was first described by Berliner [10] when he isolated a Bacillus species from the Mediterranean flour moth, Anagasta kuehniella, and named it after the province Thuringia in Germany where the infected moth was found. Although this was the first description under the name B. thuringiensis, it was not the first isolation. In 1901, a Japanese biologist, Ishiwata Shigetane, discovered a previously undescribed bacterium as the causative agent of a disease afflicting silkworms. Bt was originally considered a risk for silkworm rearing but it has become the heart of microbial insect control. The earliest commercial production began in France in 1938, under the name Sporeine [72]. A resurgence of interest in Bt has been attributed to Edward Steinhaus [105], who obtained a culture in 1942 and attracted attention to the potential of Bt through his subsequent studies. In 1956, T. Angus [3] demonstrated that the crystalline protein inclusions formed in the course of sporulation were responsible for the insecticidal action of Bt. By the early 1980's, Gonzalez et al. [48] revealed that the genes coding for crystal proteins were localized on transmissible plasmids, using a plasmid curing technique, and Schnepf and Whiteley [103] first cloned and characterized the genes coding for crystal proteins that had toxicity to larvae of the tobacco hornworm, from plasmid DNA of Bt subsp. kurstaki HD-1. This first cloning was followed quickly by the cloning of many other cry genes and eventually led to the development of Bt transgenic plants. In the 1980s, several scientists successively demonstrated that plants can be genetically engineered, and finally, Bt cotton reached the market in 1996 [104].

• Journal of Microbiology and Biotechnology
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• 제18권12호
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• pp.1915-1918
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• 2008

An entomopathogenic fungus was isolated from an infected aphid. The isolate conformed most closely to Lecanicillium attenuatum CBS 402.78 (AJ292434) based on the internal transcribed spacer (ITS) region of its 18S rDNA, and thus was designated L. attenuatum CNU-23. Laboratory and field evaluations of CNU-23 blastospores were carried out for the control of green peach aphids. The laboratory evaluations of CNU-23 revealed an aphid mortality of about 80% with an estimated $LT_{50}$ of 3.72 days after the application of CNU-23 at $1{\times}10^6$ blastospores/ml. Meanwhile, the field evaluations of CNU-23 performed on greenhouse pepper plants during the rainy season showed an aphid mortality ranging from 72% to 97%. Significant sporulation was observed in the aphids treated with CNU-23. Therefore, the results suggest that L. attenuatum CNU-23 can be used as a biocontrol agent for green peach aphids on greenhouse pepper plants.

• Journal of Microbiology and Biotechnology
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• 제16권2호
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• pp.312-317
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• 2006

The chromosomal sprD gene encoding Streptomyces griseus protease D (SGPD), a chymotrypsin-like protease, was disrupted in Streptomyces griseus by insertion of the neomysin-resistance gene. The production of chymotrypsin activity of sprD disruptant was not completely abolished, but delayed by 24 h, compared with that of wild-type strain. The aerial mycelial formation of sprD disruptant was retarded, and specifically the formation of spores was not observed in the central region of colonies. However, normal morphological development into spores was observed in the marginal region of colonies. In addition, the production of yellow pigment that might be dependent on A-factor was also decreased in the sprD disruptant, compared with that of the wild-type strain. Introduction of the sprD gene, which was placed on a high copy-numbered plasmid into S. griseus ${\Delta}sprD$, partially restored the ability of morphological development, and a significant level of sporulation was observed. When the overexpression vector for sprD, pWHM3-D, was introduced in S. griseus, there was no significant change in the chymotrypsin activity or colonial morphology, in contrast to Streptomyces lividans, indicating the presence of a tight regulation system for the overexpression of the sprD gene in S. griseus.

• The Plant Pathology Journal
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• 제17권3호
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• pp.149-153
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• 2001

A total of 2109 isolates of Botrytis cinerea were collected from infected plants fo strawberry, tomato, and cucumber in Korea from 1994 to 1996. Based on in virtotests for mycelial growth on potato-dextrose agar containing fungicides, the esolates were classified into six phenotypic groups : SSR, SRR, RSS, RRS, RSR, and RRR, representing sensitivity (S) or resistance (R) to carbendazim, procymidone, and diethofencarb. In that order the isolation frequencies of the SSR, SRR, RSS, RRS, RSR, and RRR phenotypes were 28.7, 1.1, 28.8, 39.4, 1.0, and 0.9%, respectively. Three isolates from each SSR, SRR, RSS, RRS, and RSR and an isolate of RRR phenotype were selected and evaluated for their fitness-related characteristics such as pathogenic aggressiveness, mycelial growth rate, sporulation, and sclerotial formation. Competitive abilities of the SSR, SRR, RSS, RRS, and RSR phenotypes were also compared by inculating mixtures of conidial suspensions of two phenotypes to cucumber plant, and then determining re-isolation frequencies from lesions. In general, significant differences in fitness-related characteristics, except pathogenic aggressiveness, were found not only between but also within phenotype groups. In the competitiveness tests, carbendazim-sinsitive phenotypes (SSR and SRR) were found to be more competitive than the resistant ones (RSS and RSR), whereas, the procymidone-resistant phenotypes (SRR and RRS) appeared to be more competitive than the sensitive ones (SSR, RSS, and RSR). There was no consistent dominance in competitiveness between the diethofencarb-resistant and sensitive phenotypes. The RSR phenotype was the least competitive among the five phenotypes.

• 한국식물병리학회지
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• 제11권1호
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• pp.9-16
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• 1995

Undiluted neoasozin solution (6.5% a.i.), an arsenic fungicide, was sprayed on 169 cankers of apple trees from early March to September in 1987 twice at intervals of one week without scraping off the affected barks. Among the treated cankers, 79.9% ceased to grow within 1∼7 weeks, 13.0% showed partial development, and 7.1% grew continuously to girdle the branches. The partially developed cankers, however, could also be cured by an additional spray after slightly piercing at the edge of cankers to facilitate the penetration of the chemical. When the canker growth was blocked, cankers were encircled by cracks developed at the marginal area of the cankers. If the cracks developed once, very few cankers grew beyond them. The above results suggest that the crack development may be the consequence of the host defense activity to wall off the pathogen. In addition to the curative efficacy, the neoasozin solution inhibited sporulation of the pathogenic fungus almost completely. However, the pathogen survived for more than three months in some cankers that externally appeared to be cured, suggesting that an indirect mode of action of the chemical against apple Valsa canker seems to be still more persuasive than the direct fungicidal effect. In the final examination conducted in the mid April of the next year, 72.7% of the cankers were completely cured by the two successive neoasozin treatments. Moreover the cure rate became 83.1% if that of partially developed cankers which were also completely cured by an additional treatment was also taken into account. Since 1989 when this method was widely applied in apple orchards in Korea, apple Valsa canker has been effectively controlled to reach a tolerable level.

• 한국식물병리학회지
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• 제13권4호
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• pp.195-199
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• 1997

1995년 12월 전라북도 지역 내에 유통되고 있는 시클라멘의 꽃잎 중앙부에 진회색~흑색 원형 반점을 형성하거나, 꽃잎 주변에 흑색 수침상을 나타내는 탄저병의 발생이 관찰되었다. 병반으로 붜 분리된 균은 PDA 배지상에서 회백색을 띄었으며, 8.3~15.0${\times}$2.5~6.3 ${\mu}m$ 크기의 양끝이 둥근 무색 단포의 원통형~타원형의 분새오자를 형성하였고, 갈색 곤봉형의 부착기와 이병조직에서 갈색 둥근형의 분생자층을 형성하였다. 이에 따라 시클라멘 탄저병징에서 분리한 병원균은 국내에서 미보고된 Colletotrichum gloeosporioides로 동정되었으며, 균사생장 및 분생포자 형성을 위한 배양적정 온도는 25~30$^{\circ}C$였다.

• The Plant Pathology Journal
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• 제32권4호
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• pp.281-289
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• 2016

The transcription cofactor Swi6 plays important roles in regulating vegetative growth and meiosis in Saccharomyces cerevisiae. Functions of Swi6 ortholog were also characterized in Fusarium graminearum which is one of the devastating plant pathogenic fungi. Here, we report possible role of FgSwi6 in the interaction between F. graminearum and Fusarium graminearum virus 1 (FgV1) strain DK21. FgV1 perturbs biological characteristics of host fungi such as vegetative growth, sporulation, pigmentation, and reduction of the virulence (hypovirulence) of its fungal host. To characterize function(s) of FgSWI6 gene during FgV1 infection, targeted deletion, over-expression, and complementation mutants were generated and further infected successfully with FgV1. Deletion of FgSwi6 led to severe reduction of vegetative growth even aerial mycelia while over-expression did not affect any remarkable alteration of phenotype in virus-free isolates. Virus-infected (VI) FgSWI6 deletion isolate exhibited completely delayed vegetative growth. However, VI FgSWI6 over-expression mutant grew faster than any other VI isolates. To verify whether these different growth patterns in VI isolates, viral RNA quantification was carried out using qRT-PCR. Surprisingly, viral RNA accumulations in VI isolates were similar regardless of introduced mutations. These results provide evidence that FgSWI6 might play important role(s) in FgV1 induced phenotype alteration such as delayed vegetative growth.

• 한국균학회지
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• 제25권3호통권82호
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• pp.191-201
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• 1997

유전자의 삽입에 의해 발생하는 C. parasitica의 돌연변이체중 mycovirus에 감염된 것과 같이 색소와 포자를 적게 형성하는 균주(HSM1)를 선발하였다. 선발된 균주는 형태학적 병징외에도 laccase효소의 역가와 같은 생화학적 그리고 표지 유전자들을 통해 분자 생물학적인 특징도 virus에 감염된 균주와 동일한 특징을 나타냈다. HSM1에서 돌연변이가 일어날 부위를 cloning하여 조사한 결과, 유전자 삽입 부위는 C. parasitica의 두 유전자(Cpg2와Cpg3)의 사이(intergenic space)이며 유전자의 삽입 결과, HSM1에서 Cpg2의 발현이 오히려 증가됨이 관찰되었고, 나아가 이와 같은 현상은 mycovirus 감염 균주(UEP1)에서도 일어나고 있음을 확인하였다.