• The Korean Journal of Mycology
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• v.26 no.4 s.87
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• pp.562-573
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• 1998

The symbiotic activities of arbuscular mycorrhizal fungi (AMF) by analyzing spore density, symbiosis intensity and vertical distribution of AMF spores, phytomasses of higher plants such as Calamagrostis epigeios, Imperata cylindrica, Artemisia scoparia, Aster tripolium and Sonchus brachyotus, and physico-chemical properties of soil were determined in the rhizospheres of higher plants in abandoned two coastal reclaimed lands, which were constructed in 12 and 30 years ago, respectively. Vertical distribution of the AMF spores in the rhizospheres of higher plants was restricted within 20 cm depth from soil surface, which would be closely related with vertical distribution of root system, water table and soil aeration. Of vertical distribution of soil properties, W.C., A-P and K concentrations were increased as soil depth was lowered. In the coastal reclaimed lands, symbiotic activities of the AMF such as spore density and symbiotic intensity, were conspicuously stimulated by the increase of soil pH value, organic matter and total nitrogen concentrations, but inhibited by the increase of moisture, available phosphorus and sodium concentrations in the rhizosphere soil. Phosphorus absorption by higher plants growing in the reclaimed lands increased by the rise of symbiotic activities of AMF. Since symbiotic activities of AMF were stimulated with decreasing soil phosphorus concentrations, higher plants associated with AMF absorbed a large amount of phosphorus from the soil is low phosphorus concentrations.

• The Plant Pathology Journal
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• v.32 no.3
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• pp.173-181
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• 2016

Gene disruption by homologous recombination is widely used to investigate and analyze the function of genes in Fusarium fujikuroi, a fungus that causes bakanae disease and root rot symptoms in rice. To generate gene deletion constructs, the use of conventional cloning methods, which rely on restriction enzymes and ligases, has had limited success due to a lack of unique restriction enzyme sites. Although strategies that avoid the use of restriction enzymes have been employed to overcome this issue, these methods require complicated PCR steps or are frequently inefficient. Here, we introduce a cloning system that utilizes multi-fragment assembly by In-Fusion to generate a gene disruption construct. This method utilizes DNA fragment fusion and requires only one PCR step and one reaction for construction. Using this strategy, a gene disruption construct for Fusarium cyclin C1 (FCC1), which is associated with fumonisin B1 bio-synthesis, was successfully created and used for fungal transformation. In vivo and in vitro experiments using confirmed fcc1 mutants suggest that fumonisin production is closely related to disease symptoms exhibited by F. fujikuroi strain B14. Taken together, this multi-fragment assembly method represents a simpler and a more convenient process for targeted gene disruption in fungi.

• The Korean Journal of Pesticide Science
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• v.20 no.3
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• pp.189-196
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• 2016

Several microorganisms in particular Bacillus subtilis group have been isolated from diverse places such as soils and the gastrointestinal tract of ruminants etc., and used as biocontrol agent against various plant pathogens and utilized as plant growth promoting agents. Among them, Bacillus is well known as one of the most useful bacteria for biocontrol and plant growth promotion. Bacterium GH1-13 was isolated from a reclaimed paddy field in Wando Island and identified as Bacillus velezensis using phylogenetic analysis on the basis of 16S rRNA and gyrB gene. It was confirmed that GH1-13 produced indole acetic acid (IAA) associated with promoted growth of rice root. GH1-13 showed characteristics of antagonization against the main pathogen of rice as well as diverse pathogenic fungi. GH1-13 had biosynthetic genes, bacillomycin, bacilycin, fengycin, iturin, and surfactin which are considered to be associated closely with inhibition of growth of pathogenic fungi and bacteria. This study showed that GH1-13 could be used as a multifunctional agent for biocontrol and growth promotion of crop.

• Mycobiology
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• v.45 no.3
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• pp.129-138
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• 2017

In this study, we aimed to characterize fungal samples from necrotic lesions on collar regions observed in different sweetpotato growing regions during 2015 and 2016 in Korea. Sclerotia appeared on the root zone soil surface, and white dense mycelia were observed. At the later stages of infection, mother roots quickly rotted, and large areas of the plants were destroyed. The disease occurrence was monitored at 45 and 84 farms, and 11.8% and 6.8% of the land areas were found to be infected in 2015 and 2016, respectively. Fungi were isolated from disease samples, and 36 strains were preserved. Based on the cultural and morphological characteristics of colonies, the isolates resembled the reference strain of Sclerotium rolfsii. Representative strains were identified as S. rolfsii (teleomorph: Athelia rolfsii) based on phylogenetic analysis of the internal transcribed spacer and large subunit genes along with morphological observations. To test the pathogenicity, sweetpotato storage roots were inoculated with different S. rolfsii strains. 'Yulmi' variety displayed the highest disease incidence, whereas 'Pungwonmi' resulted in the least. These findings suggested that morphological characteristics and molecular phylogenetic analysis were useful for identification of S. rolfsii.

• Journal of Korean Society of Forest Science
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• v.82 no.4
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• pp.319-327
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• 1993

The objectives of this study were to isolate ectomycorrhizal fungi associated with roots of Pinus rigida ${\times}$ P. taeda trees planted in Chonbuk and Daejon locations and to identify them, and to observe the morphology of mycorrhizae formed by the isolated fungi. Pinus rigida ${\times}$ P. taeda seedlings formed ectomycorrhizae with Rhizopogon rubescens, Rhizopogon sp. and Suillus pictus isolated from the roots of mature Pinus rigida ${\times}$ P. taeda trees, Pinus rigida ${\times}$ P. taeda seedlings formed ectomycorrhizae with Pisolithus tinetorius too. The root surface of inoculated seedlings was covered with mycelia, and Hartig net were well developed in those roots. The size of vacuole was small, and the protoplasm was planty in ectomycorrhizal cell, compared to nonmycorrhizal cell. But the size of nuclei are not changed even in ectomycorrhizal cell.

• Food Science and Preservation
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• v.23 no.5
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• pp.605-613
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• 2016

The quality and shelf life of sliced root of Platycodon grandiflorum (Doraji) treated by ozon-microbubble-heat shock (OMH) were investigated by combining modified-atmosphere packaging [MAP, ($50%O_2+15%CO_2+35%N_2$)]. The study was based on microbiological (total viable bacteria, fungi, Enterobacteriaceae and coliforms numbers), physicochemical and sensory changes. OMH treatment was effective in reducing microbial populations of the sliced Doraji, especially Enterobacteriaceae and coliforms reduced by 2 log CFU/g. However OMH-MAP treatment remained the aerobe and fungi numbers. Regarding the color, OMH-MAP delayed the change of Hunter $b^*$ and the sliced Doraji by OMH-MAP treatment exhibited lower decrease of flavor and overall acceptability compared to those by polypropylene packaging after tap water treatment (Control). The OMH and $50%O_2+15%CO_2$ MAP treatment gave better sensory quality and extended shelf-life for sliced Doraji (~3 days longer shelf-life than Control). Flavor was significantly related to overall acceptability at both Control and OMH-MAP, whereas total coliforms prevalence was associated with overall acceptability at only OMH-MAP. Therefore microbubble-heat shock treatment may improve microbial safety and sliced Doraji by OMH treatment can stored under $50%O_2+15%CO_2$ treatment for up to 7 days. Thus, OMH and MAP treatment may be used in maintaining the storage quality and marketability of sliced Doraji.

• The Plant Pathology Journal
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• v.17 no.3
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• pp.141-148
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• 2001

Postharvest decay of onion bulbs was examined by inspecting the commercial packages in the market or in storage. Bulb rot incidence was unexpectedly high, and onion bulbs with 1st quality grade were rotten most severely by 51%, followed by 32% for 2nd and 21% for 3rd grades. This indicates that larger bulbs had higher incidences of bulb rots. Major pathogens associated with basal and neck rots were Fusarium oxysporum and Aspergillus sp. or Botrytis allii, respectively, of which basal rot was most prevalent and damaging during storage. Among the epiphytic microorgani는 from onion plants, several Bacillus and Paenibacillus spp. and previously selected Pseudomonas putida and Trichoderma harzianum had inhibitory efficacy against bulb rot pathogens. Among these B. amyloliquefaciens BL-3, Paenibacillus polymyxa BL-4, and P. putida Cha 94 were highly inhibitory to conidial germination of F. oxysporum and B. allii. P. putida Cha 94, B. amyloliquefaciens BL-3, P. polymyxa BL-4, and T. harzianum TM were applied in the rhizoplane of onion at transplanting. Initially antagonist populations decreased rapidly during the first one month. However, among these antagonists, rhizoplane population densities of BL-3, Cha 94, and TM were consistently high thereafter, maintaining about 10$^4$-10$^{5}$ cells or spores per gram of onion root up to harvest time. The other bacterial antagonist BL-4 survived only for two months. TM was the most effective biocontrol agent against basal rot, with the number of rotten bulbs recorded at 4%, while that of the control was 16%. Cha 94 was effective for the first 20 days, but basal rot increased thereafter and had about the same control efficacy as that of BL-3 and BL-4. When the antagonists were applied to the topping areas of onion bulbs at harvest, TM was the most effective in protecting the stored onion bulbs from neck rotting. The second effective antagonist was BL-3. TM and BL-3 completely suppressed the neck rot in another test, suggesting that biocontrol of postharvest decay of onion using these microorganisms either at the time of transplanting or at harvesting may be promising.

• Journal of Life Science
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• v.15 no.6 s.73
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• pp.1005-1012
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• 2005

Endophytic Bacillus sp. CY22 was previously isolated from the interior of balloon flower root and showed strong antifungal activity against phytopathogenic fungi such as Rhizoctonia solnni, Fusarium oxysporum, and Phythium ultimum. Many Bacillus strains produce antifungal compound such as iturin, fengycin, and mycosubtilin. We isolated and identified antifungal compound from cell supernatant of the endophytic strain. By the MALDI-TOF mass result, the antifungal compound was similar to the known antifungal lipopeptide iturin. It was found that the purified iturin had three isoforms with protonated masses of m/z 1,043.39, 1,057.42, and 1,071.42 and different structures in combination with $Na^{+}$ ion using MALDI-TOF MS. The ita22 gene, which transacylase gene is associated with production of antifungal iturin, had an open reading frame (ORF) of 1,200 bp encoding 400 amino acids. Results of deduced amino acids sequence homology search, Ita22 was homologous with FenF (BAB69697) of Bacillus subtilis 168.

• Journal of Korean Society of Forest Science
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• v.79 no.3
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• pp.302-308
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• 1990

This study was conducted to determine the effects of mycorrhizal inoculation and ortet ages on the rooting of Quercus acutissima cuttings. The cuttings taken from 12-week-, 2-year-, 4-year-, and 20-year-old plants were rooted in mid summer in the rooting medium (vermiculite 2 : peatmoss 1 by volume) with or without Pisolithus tinctorius (Pt) and Glomus sp. inocula and IBA under intermittent misting system in an open shed. The average percentages of rooting were about 82%, 49%, 29%, and 13% for cuttings taken from 12-week-, 2-year-. 4-year-, and 20-year-old seedlings, respectively. Pt inoculation, enhanced rooting of cuttings at all age classes, except 12-week-old seedlings, with the highest enhancement(22%) observed in cuttings taken from 20-year-old trees. The highest percentage of rooting in each age group eras 88.9% in 12-week-old seedlings treated with Pt plus 3.000ppm IBA, 75% in 2-Year-old plants with 1,000ppm IBA, 58.3% in 4-year-old plants with 3.000ppm IBA and 22% in 20-year-old plants. The addition of Glomus sp. fungus inoculum failed to enhance rooting. Pt mycorrhizal inoculation enhanced root dry weight, length, and diamter of adventitious roots at cuttings taken from 12-week- and 20-year-old trees, except the cuttings taken from 4-year-old seedlings. Rooted cuttings had more total nitrogen content in the leaves than unrooted cuttings, and the greater rooting response was associated with the higher phosphorus content in the leaves.

• Journal of Mushroom
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• v.18 no.2
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• pp.125-134
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• 2020

To study the fairy ring and genet characteristics of Suillus bovinus based on thinning intensity in Pinus densiflora forests, a simple sequence repeat (SSR) analysis was performed on the fruiting bodies of the plant. In pine wood production forests, the thinning strengths applied were 34%, 45%, and 60%. As a result, the number of fruiting bodies in the 34% treatment area was 104, which was higher than that in the other treatment areas. In the 34% treatment area, fruiting bodies occurred in a circular shape, within a diameter of approximately 5 meters (m) of the trees. In the 45% treatment area, the fruiting bodies were randomly distributed between 6 to 7 m from the trees, while in the 60% treatment, fruiting bodies occurred in a narrow oval shape, 6 m from the trees. In the control area, two fruiting bodies were present around the root collar. Hybridity was confirmed in the SSR markers of Sb-CA1 and Sb-CA3. The fruiting bodies in the 34% treatment area had a He / Ho value lower than that in the 60% treatment area. In fruiting bodies of the 34% treatment area, a total of 20 genets were identified, with an average size of 14±11 ㎡; 60% of genets were formed by a single fruiting body. In fruiting bodies of the 45% treatment area, a total of 6 genets were identified and the average size was 11±12 ㎡; 50% of genets were formed by a single fruiting body. In fruiting bodies of the 60% treatment area, a total of 10 genets were identified, with an average size of 1.1±0.8 ㎡; 70% of genets were formed by a single fruiting body. Thus, the formation ratio of a new genet increases when the thinning intensity is increased.