• ALGAE
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• 제23권1호
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• pp.71-74
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• 2008

Catenella impudica (Mont.) J.Ag is an important species for human consumption from estuarine regions of Asia. Seasonal shedding of carpospores and tetraspores was quantified between January and December 2004 for natural populations of C. impudica. Vegetative and tetrasporophytic plants were available throughout the year but gametophytic plants were observed only from September to May. Tetraspore shedding was observed throughout the year and carpospores shedding was noticed only during the months when material was available. Hydrographical conditions of the estuary such as low water temperature and low salinity are correlated to the formation and release of carpospores and tetraspores in C.impudica

• 한국미생물·생명공학회지
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• 제47권1호
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• pp.96-104
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• 2019

Beauveria bassiana, one of the most common entomopathogenic fungi, has been isolated, pre defined and characterized in-house from soil of tea cultivation area. Experiments have been performed to verify the presence of chitinase as intracellular metabolite and its release as extracellular product rendering the spores with biopesticide activity. Although there are many responsible enzymes for the pest killer action of B. bassiana, binding property of chitinase depending on presence as well as absence of serine supplemented in the media has been studied with respect to the production and kinetics. A programmed investigation conclusively indicates that the isolated spore (hyphae) of B. bassiana has been metabolically enriched with the enzyme chitinase in presence of an externally added amino acid serine with its inhibitory kinetics.

• The Plant Pathology Journal
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• 제15권4호
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• pp.158-161
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• 1999

We determined threshold environmental factros to initiate infection of pepper plants by Botrytis cinerea, a fungal pathogen of pepper gray mold, in two greenhouse conditions. A new efficient spore-trapping method was developed to estimate population density of airborne conidia in the greenhouses, and spore release was measured using a Kerssies' selective medium. At a given day, spores were released greater during daytime (mostly from 7:30 am to 10:30 am and at 4:30 pm) than nighttime. Diurnal and nocturnal temperatures in the greenhouse-1 were about $25^{\circ}$ and $17^{\circ}$,and relative humidity was 100% for prolonged 24 h due to rain on December 17, 1997. Population density of air-borne conidia was 3.0$\times$103 conidia/ $0.5\textrm{m}^3$ after two days, and the initial infection occurred in ten days. During the same period of time in the greenhouse-2, diurnal temperature was about $25^{\circ}$ and nocturnal temperature was below $15^{\circ}$, and population density of air-borne conidia was 104 conidia/ $0.5\textrm{m}^3$. Under these conditions, the initial infection started in three days. This indicates that the early infection occurs under which diurnal temperature is approximately $25^{\circ}$, nocturnal temperature is maintained below $15^{\circ}$, and population density of air-borne conidia is 104 conidia/ $0.5\textrm{m}^3$ at saturated relative humidity condition.

• 한국양식학회지
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• 제18권4호
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• pp.299-304
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• 2005

이 연구는 동해 연안에서 토속종인 개다시마(K. crassifolia) 와 이식종인 다시마(L. japonica)의 실내 배양에서 온도와 조도에 대한 특성을 비교하였다. 유주자 단계에서 수온 $15{\~}20^{\circ}C$도일 때 24시간 안에 $95\%$의 포자 발아가 이루어진 반면 개다시마는 48시간 안에 $90\%$를 보였다. 배우체의 성장은 $10^{\circ}C$와 $15^{\circ}C$도에서 생장이 좋았는데 이입종인 다시마는 $80{\~}l20{\mu}mol{\cdot}m^{-2}s^{-1}$ 고조도에서 최대를 보였고 토속종인 개다시마는 $40{\~}80{\mu}mol{\cdot}m^{-2}s^{-1}$ 낮은 조도에서 최적을 보였다. 아포체의 성장은 개다시마는 $10^{\circ}C$, $40{\mu}mol{\cdot}m^{-2}s^{-1}$ 조도에서 생장이 좋은 반면 다시마는 수온 $10{\~}20^{\circ}C$와 $40{\~}l20{\mu}mol{\cdot}m^{-2}s^{-1}$ 조도의 다양한 조건에서 생장이 좋게 나타났다. 개다시마의 배양 최적 조건은 이입종 다시마에 비해 수온과 조도의 범위로 볼 때 매우 협소하게 나타나 이는 개다시마가 깊은 곳에 서식하는 바다환경의 특성을 잘 반영해주고 있다.

• The Plant Pathology Journal
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• 제16권3호
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• pp.147-150
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• 2000

Sporulation patterns of rice blast fungus were studied at relatively later stages of leaf blast and neck blast seasons in Icheon, Korea. This experiment was done by detaching lesion-bearing leaves and panicle bases. The number of conidia remaining on the leaf blast lesions of different cultivars from Jul 20 to Jul 23 ranged from 3,640 to 82,740 spores. More conidia were observed on the adaxial surface because they were released from abaxial surface. After heading, sporulation was observed from the lesions on the flag leaves but the number of spores was less than in the late July. Detached panicle bases or uppermost internodes infected by Pyricularia grisea produced abundant amount of conidia. Among these panicle bases, 30.1 mm size lesion recorded the highest count of 244,560 spores. When we compared the sporulation amount using the KY-type spore trap, more conidia were recorded from intact lesions than from the lesions which removed conidia and conidiophore The ratio of conidia release against total sporulation ranged from 20.5%-25.0% for leaf blast and 8.2%-25.3% in the neck blast. Effective inoculum potential was also discussed.

• 미생물학회지
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• 제22권3호
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• pp.135-142
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• 1984

The effect of biotin on the growth and sporulation of Bacillus subtilis SNU816 was investigated. When B. subtilis SNU816 was cultured on glucose as a sole carbon source, the growth was retarded markedly and usually ceased at early log phawe. But by addition of biotin to this medium, normal, rapid growth was restored. The growth rate was increased proportionally according to the concentration of exogenous biotin until it reached to 0.05㎍/ml, at which about three fold rapid growth was achieved. Also biotin was required for optimum sporulation for it facilitated the complete utilization of both glucose(Glc) and glutamic acid(Glu). Without biotin in Glc+Glu medium, about 40% of glutamic acid was remained unutilized. The dipicolinic acid content of cells cultured in Glc+Glu medium without biotin was markedly small and sporulation was suppressed before free spore release. Since biotin could be partiallyreplaced by one of TCA cycle intermediates such as oxalacetic acid, citric acid, or glutamic acid in enhancing growth in Glc medium, it was postulated that this strain might have a defect in converting pyruvate to oxalacetate which process is known to be mediated by pyruvate carboxylase that requires biotin as a cofactor.

• Mycobiology
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• 제45권3호
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• pp.204-208
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• 2017

Nosema ceranae is an obligate intracellular fungal parasite that causes mortality in honey bees and enhances the susceptibility of honey bees to other pathogens. Efficient purification of Nosema spores from the midgut of infected honey bees is very important because Nosema is non-culturable and only seasonably available. To achieve a higher yield of spores from honey bees, in this study, we considered that the initial release of spores from the midgut tissues was the most critical step. The use of 2 mm beads along with enzymatic treatment with collagenase and trypsin enhanced the homogenization of tissues and the yield of released spores by approximately 2.95 times compared with the use of common 3 mm beads alone. The optimal time for the enzyme treatment was determined to be 1 hr as measured by the yield and viability of the spores. A one-step filtration using a filter paper with an $8-11{\mu}m$ pore size was sufficient for removing cell debris. This method may be useful to purify not only N. ceranae spores but also other Nosema spp. spores.

• 식물병연구
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• 제10권4호
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• pp.209-216
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• 2004

The circular leaf spot of persimmon is occurred almost every place where persimmon is cultivated, especially the disease outbreak severely in southern part of Korea. The disease reveals unusually long incubation period after pathogen invade into leaf tissue and no practical control measure is available once the symptom has appeared. Most of the farmers just follow the suggested spray schedules calculated on the basis of weather condition of ordinary years. Therefore the damages due to circular leaf spot greatly differ year after year. In this article, we tried to describe and summarized the investigation on the circular leaf spot pathogen, Mycosphaerella nawae, related to disease outbreak such as overwintering of pathogen, inoculum formation and spread, incubation period after infection, and secondary inoculum. With the summary of these results, we suggest the disease cycle of circular leaf spot of persimmon. The pathogen overwinters in diseased leaves as mycelial form or pseudoperithecial premodium. The pseudoperitheria become matured in spring as the temperature raise and forms asci and ascospores. The maturation of pseudoperithecia are closely related to the temperatures during March and early April. The ascospores completely mature in early May and the ascospores released when the pseudoperithecia absorbed enough moisture after rainfall. The release of ascospores are diverse greatly with the variation of maturity of pseudoperithecia. Generally the spore start to release from middle of May to early of July. Duration of ascospore release is depend on the weather condition of particular year, especially amount and number of precipitation. The ascospores produced from pseudoperithecia is known to the only inoculum for circular leaf spot disease. But according to the results obtained from our investigations, the conidia formed on the lesions which incited by natural infection. This conidia are infectious to persimmon leaves and formed identical symptom as natural infection. The time of producing secondary inoculum of circular leaf spot of persimmon is considered too late to develop new disease. Generally the importance of secondary inoculum is low but the conidia produced in early September are competent to develop new disease and new infection also significantly affect to harvest of persimmon. The importance of circular leaf spot disease is recognized well to farmers. The approaches to control of the disease should be initiated on the basis of the knowledges of inoculum dynamics and ecology of disease development. The forecasting system for circular leaf spot is need to be developed.

• 한국작물학회지
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• 제27권4호
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• pp.361-370
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• 1982

The effects of climatic factors on organisms lire variable and complex, and it, however, can be interpreted in terms of those on the distribution and those on the population densities. The distribution of an organism may largely be determined by the temperatures, except some temporal organisms which are depended on the air mass movements. Population density of an organism is determined by various climatic factors, such as previous winter temperature, temperature of growing season and rainfall. The start of growing season of the rice plants has been shifted to earlier since last decade in Korea. This may mean that the overall climatic condition during the growing season might be considerably different from those in past years, and such a difference in climatic conditions might have close relation with the recent status of the diseases and insect pests through direct effects on the physiology and population dynamics of the organisms, as well as through on the biotic associations of the pest organisms. The white back planthopper and brown planthopper have become the key insect pests in Korea in recent years. They are migratory and have high reproductive pontentials and more generations than average residential insects. The synchronization of the migrants and physiological condition of the rice plants seems to be the important factors in relation to the recent outbreaks of these insects; the high reproductive rate can be obtained with the growth stage of rice being 30-50 days after transplanting. The modication of the microclimate associated with high plant density and some other introduced new cultural techniques also have some relation with the outbreak. The key diseases of the rice are the blast disease, sheath blight and the bacterial leaf blight. For the rice blast, the seedling blast and leaf blast during the early growing season and the neck blast, have become more serious, the former may be related to hotbed nursery and the later may be related to the high humidity in early August, and synchronization of the heading time which has been shifted to early part from middle or late part of August. In general, for the rice diseases, the development of the new races have been the most serious which are largely resulted from the introduction of the new varieties, but it also seems to be related with the prolonged periods of the favorable condition associated with the shifted growing seasons. In general, the diseases and insect pest problems have become much more variable and complex, and control measures should be based on the thorough knowledge of the ecology of the pest organisms, that is, effects of various environmental factors on the disease cycle; spore release, spore deposition, infection, colonization and sporulation of the disease organisms, and those on the development, reproductive potentials, dispersal, age specific responses of the insects. The well organized real-time pest management systems, such as alfalfa weevil management system developed at the Purdue University in U.S., is the prime importance for the implementation of the pest management principles.

• 한국균학회지
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• 제40권1호
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• pp.39-43
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• 2012

독특한 자연환경과 다양한 생물상을 지닌 제주도에서 지역민들에게 이용되어 왔던 자생버섯에 대한 전통지식을 조사하였다. 제주도 전 지역을 조사 대상으로 하였으며, 제주와 서귀포시 내에 있는 7개 읍과 4개의 면을 대상으로 총 50개의 마을을 조사하였으며 50~90대 사이의 노인들 93명을 방문하여 녹취하고 야장을 작성하였다. 그 결과 제주도에서 이용되어온 야생버섯은 모두 23종으로 나타났고, 그 중 독버섯은 2종, 약용버섯은 7종, 민속신앙에 이용되었던 버섯이 2종, 이용되지는 않았으나 관심 대상이었던 버섯이 2종, 그리고 식용버섯은 12종으로 조사되었다. 또한 야생버섯을 이용하는 전통지식으로 267건의 전통지식이 수집되었다. 그 중 식용버섯은 12종에서 197건의 전통지식이 수집되었고, 독버섯에 2종에서 43건이 수집 되었으며, 약용버섯에 대한 정보는 7종에서 16건의 전통지식이 조사되었다. 특이한 점은 동물의 분변이나 퇴비에 발생하는 Cyathus stercoreus을 이용하여 포자괴(spore mass)의 방출 상태를 보고 농사의 길흉을 점쳐왔다는 점이었다. 이는 제주지방만의 독특한 전통지식으로 추정된다.