• The Korean Journal of Mycology
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• v.22 no.4
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• pp.394-409
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• 1994

The symbiotic activities of arbuscular mycorrhizal fungi(AMF) such as spore density, symbiotic intensity and vesicle density, phytomasses of higher plants such as Calamagrostis epigeios, Imperata cylindria, Artemisia scoparia, Aster tripolium and Sonchus brachyotus and seasonal change of the AMF activities, electric conductivity and zinc contents in plant and soil were determined in the rhizospheres of higher plants at abandoned old coastal reclaimed lands, where constructed in 12 and 30 years ago. If plants of reclaimed land classified to salinity, symbiotic activities of AMF were high in order of obligate halophyte, facultative halophyte and glycophyte. Also, those plants classified to life form, symbiotic activities of AMF were high in order of annual, biennial and perennial plants. Seasonal variation of spore density, one of symbiotic activities showed that the plateau density maintained continuously from the end of growing season of the higher plants to next spring. For this reason, it regarded that reproduction of AMF spore would be formed in autumn, when the higher plants will be developed. Seasonal change of symbiosis intensity, other symbiotic activities, however, showed that the highest symbiosis intensity occurred in spring and summer but the lowest in autumn. In relationships among symbiotic activities, spore density was directry proportional increase of symbiosis intensity. Moreover, phytomass of higher plants also was directly proportional to increase the spore density as well as symbiosis intensity. Vesicle density, however, did not any correlation with the phytomass, spore density and symbiosis intensity. From these results, it can know that both spore density and symbiosis intensity are strongly possible to use as the measure of symbiotic activity owing to symbiosis of tho-AMF, the more absorption of zinc by the higher plants carried out the less concentration of zinc in the soil.

• Korean Journal of Organic Agriculture
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• v.19 no.3
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• pp.343-355
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• 2011

This work was studied the effects of spore density and infection of arbuscular mycorrhizal fungi (AMF) for no-tillage organic cultivation of pepper with wintering green manure crops cultivation in greenhouse field. Spore density of arbuscular mycorrhizal fungi (AMF) in green manure crops was 189 spores/30g fresh soils in control including alive spore (82 spores). Spore density of AMF in all green manure crops was totally 196~226 spores/30g fresh soil and alive spore was 84~112 spores/30g fresh soil. Spore density of AMF in soils of Pepper crop was range of 48.0~56.7 spores/30g fresh soils after cultivation of green manure crops. Infection structure of AMF was not significantly difference in soils of green manure crops and Pepper crop after cultivation of green manure crops. Infection rate of AMF in roots of green crops was low level by 2.8% in giant chickweed, 7.4% in rye, 9.3% in hairy vetch. Infection rate of AMF in roots of barley was the highest level by 20.3%. Infection rate of AMF in roots of Pepper crop was range of 5.2~7.2% after cultivation of green manure crops Also, infection rate of AMF in roots of Pepper crop was 8.1% after the harvest of barley. Infection structure of AMF in barley very well consisted of network with internal hyphae, while hairy vetch and rye tended to no network. There was not a significant relationship between spore density in soils and infection rate of AMF in rhizosphere of Pepper.

• The Korean Journal of Mycology
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• v.21 no.3
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• pp.235-245
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• 1993

The symbiotic properties of arbuscular mycorrhizal fungi(AMF) such as the absence and/or presence of symbiosis, spore density, and six factors of phycochemical properties of soil were investigated in the rhizosphere of seven sand dune plants and three control plants around Kum river. The infection of AMF was confirmed in all plants. Three genera, nine species of the AMF spores were identified in the sand dune; Ac. scrobiculata, G. aggregatum, G. convolutum, G. diaphanum, G. dimophicum, G. geosporum, G. vesiculiferum, G. tortuosum, S. pachycaulis. All of them were also found in the control, but S. pachycaulis were only separated in the sand dune. In the control, three genera, four species were identified; G. flavisporum, Gi. margarita, Sc. gregaria. Sc. persica. The species specificity was not found between the sand dune plant and AMF. However, the AMF was thought to be correlated with the soil factors. The spore density was stimulated with increase of the organic matter and the nitrogen content, but inhibited with the water content and the phosphorus content. In respect of the seasonal factor, the spore density was increased in the late growth period of plants.

• Research in Plant Disease
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• v.11 no.1
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• pp.43-47
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• 2005

To investigate control efficacy of flusulfamide GR (granule) on Chinese cabbage clubroot caused by Plasmodiophora brassicae, experiment was accomplished in field located in Gangneungshi alpine area contaminated by P. brassicae. Flusulfamide GR provided control value of 84.6% and that was statistically significant difference from standard fungicides containing untreated control. To investigate ratio of reduction of resting spore according to fungicide treatment, soil of Chinese cabbage field before and after fungicide treatment were sampled and investigated density of resting spore. Resting spore density was not uniform in soil before fungicide treatment. Therefore, to investigate control efficacy of fungicide against clubroot, investigation on resting spore density was conducted before experiment and reflected in experimental design. Flusulfamide GR and DP (dust powder) provided 64.2% and 63.7% of reduction of resting spore on field soil after fungicide treatments. This result indicated that control efficacy of the fungicides was correlated with reduction of resting spore of P. brassicae. The increasing rate in fresh weight of above-ground part of Chinese cabbage by flusulfamide DP and GR, fluazinam DP and trifloxystrobin SC (suspension concentrate) was 14.3%, 13.0%, 13.8% and 3.8%, respectively. From above result, flusulmide GR have outstanding control efficacy against clubroot of Chinese cabbage and is effectively decreasing of resting spore density in soil.

• The Korean Journal of Pesticide Science
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• v.7 no.3
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• pp.159-168
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• 2003

With microtiter plate, the assay method was developed for detecting the fungicidal activity of new compounds against spore germination, spore adhesion and mycelial growth of Colletotrichum sp. JC24 cal1Sing red pepper anthracnose. Also, the effects of some commercialized fungicides on fungal development like above mentioned were investigated by measuring the optical density of mycelia grown into wells of microtiter plate. For the standardization of assay method, some factors, such as the treatment of MTT and/or propanol, inodulum density and incubation period, affecting on mycelial optical density were investigated. For obtaining precise and consistent mycelial optical density, it was necessary the treatment of MTT for 12 hrs and propanol for 1 hr. inoculum density adjusted to $1\times10^5$ spores/mL and incubation period for 36 hrs at $25^{\circ}C$. For fungicidal activities, 6 protective fungicides, 6 ones inhibiting sterol biosynthesis, and one inhibiting respiration were used in this study. While mancozeb, chlorothalonil and dithianon among 6 protective fungicides inhibited strongly spore germination, adhesion, and mycelial growth at $6.25{\mu}g/mL$, propineb, iminoctadine and fluazinam inhibited intermediately spore germination and mycelial growth at $100{\mu}g/mL$. Washing above 3 fungicides with new PD broth, their activity against spore adhesion decreased. With hexaconazole, tebuconazole and myclobutanil, the tendency of the activity against fungal differentiation of the early infection stage was similar to the latter group of protective fungicides, showing the decrease of the inhibitory activity against spore adhesion by washing 2 hrs after incubation. However, kresoxim-methyl inhibited spore adhesion distinctly, depending on the applied concentrations. Based on these results, it might be able to assess the fungicidal activity of many compounds against spore germination, adhesion and mycelial growth by the use of microtiter plate in vitro. Using the assay developed in this report, it was possible to investigate the inhibitory activity of some commercialized fungicides, too.

• Journal of Korean Society of Forest Science
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• v.98 no.5
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• pp.539-547
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• 2009

This study was conducted to investigate the arbuscular mycorrhizal fungal biodiversity, spore density and root colonization in relation to site ages at expressway cut-slopes in Korea. Stabilization of exposed surface involved soil amendments and spraying seed mixture of turf grasses and/or nitrogen-fixing shrub species. Eighteen sites were selected with varying ages (2 to 16 years). Soil samples collected in October from each site were analyzed for fungal diversity and spore counts. Fine root samples from the plants were assayed for fungal colonization. Of the total 37 plants inspected in the sites, 26 species had endomycorrhizal colonization with an average root colonization rate of 18%, and with a range from 1 to 67%. The average endomycorrhizal colonization rate of initially introduced Festuca arundinacea which became the most dominant grass in later stage showed 22.8%, while that of Lespedeza bicolor which became the most dominant woody species were 21.6%. Naturally-invading Robinia pseudoacacia showed higher colonization rate in the old sites. Although site age did not show significant effects on fungal diversity, the root colonization rates of initially introduced plants decreased with the site aging, while those of invading plants increased with aging of the sites. The soil chemical properties, pH, N, and P contents, were negatively correlated with spore density, root colonization and endomycorrhizal species diversity. A total of forty arbuscular mycorrhizal fungal species in seven genera were identified. Of the 40 species, Acaulospora lacunosa, Glomus aggregatum, Glomus constrictum, Scutellospora erythropa, and Acaulospora spinosa were the five most dominant species in the decreasing order.

• Journal of Sericultural and Entomological Science
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• v.31 no.2
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• pp.113-120
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• 1989

A new microsporidia (S85) was isolated from the silkworm, Bombyx mori L. in Suwon, Korea in 1985. The electron microscopic observation of the fine structure of the spore was studied for the characterization of the new microsporidia and its taxonomic position. The sporewall was composed of three different electron dense layers and the spore surface was rouph and wrinkled. The polaroplast has two parts which differed in the arrangement of the lamellae. The polarfilament was isofilar with thirteen coils and it was consisted of eight concentric layers of different electron density. The spore contained a single nucleus and the pansporoblast appeared as a thin ballon-like structure surrounding the spore. The membrane was generally smooth and shown occationally wrinkled.

• KSBB Journal
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• v.16 no.1
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• pp.30-35
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• 2001

High cell density culture of Bacillus thuringiensis was conducted in fed-batch culture and TCRC using a bioreactor incorporating ceramic membrane filter. Cell growth of B. thuringiensis in fed-batch culture increased linearly, which was well matched by the results of cell growth modeling. In spite of the slower growth rate during fed-batch culture, no spore formation was observed, which was contrary to the results of continuous culture. Changing culture mode to batch culture after fed-batch operation induced a 2.7$\times$$10^9$ CFU/mL spore concentration using a 300 g/L glucose feed concentration. In TCRC operation incorporating ceramic filter within the bioreactor, the effect of glucose feed concentrations on the cell growth and spore formation of B. thuringiensis was determined. A maximum cell concentration of 1.8$\times$$10^{10}$ CFU/ml, which corresponds to 82.6 g-cell/L, was obtained in the TCRC using a 50 g/L glucose feed concentration. In the TCRC, cell growth increased linearly and glucose concentration was limited, which agreed well with the results of cell growth modeling. No spore formation was observed except when 1 g/L of glucose was fed. Changing to batch culture induced a 1.2$\times$$10^{10}$ CFU/mL of spore concentration, which was the highest spore concentration obtained among the various culture modes examined. The optimal glucose feed rate was found to be 0.55 g-glucose/h.

• The Plant Pathology Journal
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• v.15 no.4
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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.

• Korean Journal Plant Pathology
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• v.14 no.4
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• pp.325-330
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• 1998

On the basis of the fact that the pycnidiospore of Botryosphaeria dothidea, the causal fungus of apple white rot is a typical water borne spore, a method for quantitative analysis of pycnidiospore dispersal from the warts produced on the diseased apple tree stem was developed. The warts on which cracks developed either on or around them were cut off at the base, and shaked in the water for 4hours at 2$0^{\circ}C$, in which condition the maximum number of spores were released. The volume of shaking solution was calculated as 1 ml per one wart. At the end of shaking, Trio, a household detergent was added to the shaking solution to the concentration of 0.1%, and shaked for additional 10 minutes at 35$^{\circ}C$ to take off the spores attached on the glass ware. One milliliter of the spore suspension thus prepared were passed through transparent membrane filter (pore size : 3.0 ${\mu}{\textrm}{m}$), and the spores attached on the filter were counted under a microscope ($\times$200) after staining them with lactophenol supplemented with aniline blue. The results thus obtained were statistically consistent when at least 30 warts were used simultaneously in single shaking. This method can be applicable in the elucidation of ecology of sporulation and spore dispersal, and also in the screening of the sporulation inhibitor which can be used in the control of the disease by reducing the inoculum density.