• Research in Plant Disease
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• v.15 no.3
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• pp.202-208
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• 2009

The genetically modified leaffolder-resistant (Cry1Ac1) rice plant was evaluated for the changes of resistance by comparing the occurrence of major diseases with a japonica type Korean rice variety, Nakdong which was the mother plant of the transgenic rice event, in greenhouse and field conditions. There was no difference in the occurrence of sheath blight and Helminthosporium blight between the two varieties in the fields. We couldn't find any difference of resistance for fungal blast and bacterial leaf blight by artificial inoculation in greenhouse. There was also no difference in the susceptibility to sheath blight in artificial inoculation tests confirming the results in the fields. The possibility of gene transfer of Bar and Cry1Ac1 from the genetically modified rice plant to naturally infected pathogens such as Fusarium moniliforme and Pyricularia oryzae in the field conditions was tested by PCR. And the possible transfer of those genes by continuous inoculation of Xanthomonas oryzae pv. oryzae and Rhizoctonia solani was also tested. However, we couldn't find any possibility of transfer of the genes in natural and artificial conditions.

• Korean Journal of Medicinal Crop Science
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• v.26 no.3
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• pp.248-253
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• 2018

Background: Dazomet are widely used as soil fumigant to solve soilborne problems, and the degradation intermediates are toxic to nematodes, fungi, bacteria, insects and weeds. Methods and Results: The effects of cultivation of green manure crop, maize before and after soil fumigation on the control of ginseng root rot disease were compared using soil where 6-years-old ginseng was harvested. Fumigant (dazomet) were used for soil fumigation in May and September, respectively. Maize was grown for soil management before and after soil fumigation. After May fumigation, the sowing date of maize was delayed by 15 days and thus its dry weight was decreased significantly. Maize cultivation after May fumigation increased pH but decreased EC, $NO_3$, $P_2O_5$, and K significantly. Maize cultivation after May fumigation decreased fungi population and the ratio of fungi and bacteria. Growth of 2-years-old ginseng was improved and the incidence of ginseng root rot was significantly decreased by maize cultivation after May fumigation. After harvesting 2-years-old ginseng, the population of Cylindrocarpon destructans was not different between treatment of May and September, but Fusarium solani showed a significant increase in September fumigation after maize cultivation. Conclusions: Maize cultivation after soil fumigation was effective in inhibiting ginseng root rot by the amendment of mineral composition and microorganism in fumigated soil.

• Korean Journal of Medicinal Crop Science
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• v.24 no.2
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• pp.136-142
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• 2016

Background: Root diseases caused by Cylindrocarpon destructans and Fusarium solani decrease the yield and quality of ginseng. Cylindrocarpon root rot is a major disease caused by replant failure in ginseng fields. Methods and Results: Solarization of infested greenhouse soil was carried out during the summer season after applying green manure (Sudan grass) and Calcium Cyanamide (CC) on the soil. Mycelium and conidia of C. destructans died at $40^{\circ}C$ after 15 h, but they did not die at $35^{\circ}C$ after 15 h. They also died after keeping the soil at $40^{\circ}C$ for 2 h daily for 9 days, and at $45^{\circ}C$ for 8 days, but they did not die at $38^{\circ}C$ for 9 days. Maximum soil temperature was $55.4^{\circ}C$ at 5 cm depth, $48.7^{\circ}C$ at 10 cm, $44.7^{\circ}C$ at 15 cm, $42.5^{\circ}C$ at 20 cm, and $31.9^{\circ}C$ at 30 cm by incorporating green manure into the soil and using solarization. Solarization using green manure mixed with CC was the most effective in decreasing soil-borne pathogens of 2-year-old ginseng. However, the addition of CC decreased the root weight due to the increase in EC and $NO_3-N$. Conclusions: Soil disinfection using green manure and solarization in a greenhouse environment was effective in inhibiting root rot, however, it did not completely kill the soil-borne pathogens.

• KSBB Journal
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• v.21 no.1 s.96
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• pp.42-48
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• 2006

Bacillus subtilis KMU-13 was isolated from the Lillehammer forest soils at Norway and shown a strong antifungal activity on cucumber scab, Cladosporium cucumerinum KACC 40576. B. subtilis KMU-13 produced a maximum level of antifungal substance under incubation aerobically at $30^{\circ}C$, 180 rpm for 48 hours in LB broth containing 0.5% maltose and 0.5% bactopeptone and initial pH adjusted to 6.0. Butanol extract of cultured broth was confirmed inhibitory zone by plate assay and Rf 0.64 value substance by thin layer chromatography (TLC) represented high antifungal activity against C. cucumerinum KACC 40576 and also shown fungal growth inhibitory activity against Botytis cinerea KACC 40573, C. gloeosporioides KACC 40804, D. byoniae KACC 40669, F. oxysporum KACC 40037, F. oxysporum KACC 40052, F. oxysporum f. sp. radicis-lycopersici KACC 40537, F. oxysporum KACC 40902, M. cannonballus KACC 40940, P. cambivora KACC 40160, R. soiani AG-1 KACC 40101, R. solani AG-4 KACC 40142, and S. scleotiorum KACC by agar diffusion method.

• The Korean Journal of Pesticide Science
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• v.12 no.4
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• pp.307-314
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• 2008

Sixty compounds such as alkylphenyl fluorobenzoate esters from thymol(I), 5-isopropyl-3-methylphenol (II), 4-isopropyl-3-methylphenol (III), 2-sec-butylphenol (IV) and 4-sec-butylphenol (V) were synthesized. These derivatives were identified by IR, $^1H$-NMR spectrometer and GC/MS. Their in vivo antifungal activities were tested against phytopathogens such as Phytophthora infestans, Botrytis cinerea, Colletotrichum orbiculare and Rhizoctonia solani. As the result, 2-sec-butylphenyl 2,5-difluorobenzoate (IV-6) and 4-sec-butylphenyl 2,5-difluorobenzoate (V-6) showed 90% above antifungal activity against Botrytis cinerea. 2-Isopropyl-5-methylphenyl 2,3,6-trifluorobenzoate (I-11), 2-isopropyl-5-methylphenyl 2,4,5-trifluorobenzoate (I-12), 5-isopropyl-3-methylphenyl 2,3,6-trifluorobenzoate (II-11), 4-isopropyl-3-methylphenyl 2,3,6-trifluorobenzoate (III-11) and 4-isopropyl-3-methylphenyl 2,4,5-trifluorobenzoate (III -12) showed 90% above potent antifungal activity against Colletotrichum orbiculare.

• Journal of Microbiology and Biotechnology
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• v.24 no.9
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• pp.1149-1161
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• 2014

Cotton plants were sampled and ranked according to their resistance to Verticillium wilt. In total, 642 endophytic fungi isolates representing 27 genera were recovered from Gossypium hirsutum root, stem, and leaf tissues, but were not uniformly distributed. More endophytic fungi appeared in the leaf (391) compared with the root (140) and stem (111) sections. However, no significant difference in the abundance of isolated endophytes was found among resistant cotton varieties. Alternaria exhibited the highest colonization frequency (7.9%), followed by Acremonium (6.6%) and Penicillium (4.8%). Unlike tolerant varieties, resistant and susceptible ones had similar endophytic fungal population compositions. In three Verticillium-wilt-resistant cotton varieties, fungal endophytes from the genus Alternaria were most frequently isolated, followed by Gibberella and Penicillium. The maximum concentration of dominant endophytic fungi was observed in leaf tissues (0.1797). The evenness of stem tissue endophytic communities (0.702) was comparatively more uniform than the other two tissues. Eighty endophytic fungi selected from 27 genera were evaluated for their inhibition activity against highly virulent Verticillium dahliae isolate Vd080 in vitro. Thirty-nine isolates exhibited fungistasis against the pathogen at varying degrees. Seven species, having high growth inhibition rates (${\geq}75%$), exhibited strong antifungal activity against V. dahliae. The antifungal activity of both volatile and nonvolatile metabolites was also investigated. The nonvolatile substances produced by CEF-818 (Penicillium simplicissimum), CEF-325 (Fusarium solani), CEF-714 (Leptosphaeria sp.), and CEF-642 (Talaromyces flavus) completely inhibited V. dahliae growth. These findings deepen our understanding of cotton-endophyte interactions and provide a platform for screening G. hirsutum endophytes with biocontrol potential.

• Korean Journal of Organic Agriculture
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• v.22 no.1
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• pp.129-145
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• 2014

To evaluate the potential of Hypochoeris radicata L. for the development of environment-friendly organic materials, its growth characteristics, allelopathic effects and antifungal activity was investigated. The growth characteristics of H. radicata L. was investigated by measuring comparative number of shoot and flower, and the diameters of clones in mowing areas and non-mowing areas, respectively. As a result, the number of shoot and flower, and diameters of clones of H. radicata L. grown in mowing areas were much higher than those grown in non-mowing areas. Water extracts of H. radicata L. inhibited seed germination, and shoot, root and root hair growth of 14 test plants including Trifolium pratense, Festuca myuros, Bidens bipinnata and finally reduced heir biomass remarkably. The inhibitory effect of the extract was different depending on the kind and the part of tested plants. The extracts showed high antifungal activity against Pythium spp. and Phytophthora However, it showed comparably less antifungal activity against Rhizoctonia solani than Pythium spp. and Phytophthora. In conclusion, cutting H. radicata L. resulted increase of its vegetative and seed propagation and helped it to form large colony. Also it had an effect on growth of microbes and germination and growth of other plants. Therefore H. radicata L. holds the competitive dominant position in plant ecosystem in Jeju Island and it can be used as candidate of environment-friendly organic materials.

• The Korean Journal of Mycology
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• v.41 no.2
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• pp.118-126
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• 2013

The experiment was carried out to analyze the inhibition effect of plant pathogenic fungi and growth promotion activity induced by the bacterial strains isolated from peatmoss. Among the isolated bacterial strains, B10-2, B10-4, B10-5 and B10-6 which showed more than 30% inhibition rate against Botrytis cinerea and Rhizoctonia solani in vitro, were further analyzed in the greenhouse for the growth promotion activity on lettuce (Lactuca sativa), pak-choi (Brassica compestris L. ssp. chinensis) and Chinese cabbage (Brassica campestris L. ssp. pekinensis). The results showed the treatment of B10-4 on lettuce showed the highest growth promotion activity with the leaf area ($169.17cm^2$), fresh weight (leaf: 40.29 g, root: 8.80 g)and dry weight (leaf: 11.24 g, root: 4.17 g), which was about two folds as compared to control. On pak-choi, the growth promotion rate was the highest with the leaf area of $112.87cm^2$, leaf fresh weight of 60.70 g, root fresh weight of 3.37 g, leaf dry weight of 14.34 g, and root dry weight of 1.90 g. As a result of treatment of B10-13 on chinese cabbage, the growth promotion rate was the highest with the leaf area ($293.56cm^2$), fresh weight (leaf: 113.67 g, root: 2.40 g) and dry weight (leaf: 6.03 g, root: 0.53 g). The production of Indole Acetic Acid (IAA) and Indole-3-Butylic Acid (IBA) were also analyzed in these bacterial isolates. The IAA and IBA analyses were carried out in all bacterial isolates each day within the 5 days of incubation period. The highest production of IAA was observed with $112.57{\mu}g/mg$ protein in B10-4 after 3 days of incubation and IBA production was the highest in B10-2 with $58.71{\mu}g/mg$ protein after 2 days of incubation. Also, phosphate solubilizing activity was expressed significantly in B10-13 in comparison to that of other bacterial isolates. Bacterial identification showed that B10-2 was Bacillaceae bacterium and B10-5 was Bacillus cereus, B10-4 and B10-6 were Bacillus sp. and B-13 was Staphylococcus sp. by ITS sequence.

• Microbiology and Biotechnology Letters
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• v.41 no.3
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• pp.292-299
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• 2013

In this study, we analyzed the changes in fungal populations of red-pepper fields employing eco-friendly farming methods, such as microbial agents and crop rotation, by using polymerase chain reactions coupled with denaturing gradient gel electrophoresis (PCR-DGGE). Primer specific for fungi were used to determine the contribution of domains to the microbial community. Analysis of planted and non-planted soil samples applying PCR-DGGE technology offered evaluation of long-term patterns in fungal species richness. To evaluate the stability of DGGE patterns from different soils, comparison of planted and non-planted soil samples were compared using PCR-DGGE. The number of DNA fragments obtained from all planted soil samples by DGGE separation was far greater (14 to 15 bands) than that of the non-planted soil samples (3 to 4 bands). In addition, 14 bands were observed from crop continuation soil treated with agrochemicals and 18 bands from crop rotation soil treated with microbial agents. The PCR-DGGE analysis suggests that the use of crop rotation and microbial agents benefits the fungal community more than crop continuation using agrochemicals. These results indicate that crop rotation with microbial agents was better able to support beneficial organisms, enable more effective biological control and maintain a healthier balance of nutrients, organic matter and microorganisms.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2020.12a
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• pp.61-61
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• 2020

This experiment was carried out using artificial bed soil and LED in the plastic film house(irradiation time: 07:00-17:00/day). Seedlings(n=63 per 3.3 m²) of ginseng was planted on May 17, 2018. LED was combined with red and blue light in a 3:1 ratio and irradiated with different light intensity(40-160 µmol/m²/s). Average air temperature from April to September according to the light intensity test was 20.4℃-20.9℃. Average artificial bed soil temperature was 20.1℃-21.7℃. The test area where fluorescent lamp was irradiated tended to be somewhat lower than the LED irradiation area. The chemical properties of the test soil was as follows. pH levels was 6.6-6.7, EC levels 0.9-1.3 dS/m and OM levels 30.6-32.0%. The available P₂O₅ contents was 73.3-302.3 mg/kg. Exchangeable cations K and Ca contents were higher than the allowable ranges and mg content was high in the fluorescent lamp treatment. The photometric characteristics of LED light intensity are as follows. The greater the light intensity, the higher the PPFD(Photosynthetic Photon Flux Density) value, illuminance and solar irradiation. Fluorescent lamp treatment had high illuminance value, but PPFD and solar irradiation were lower than LED intensity 40 µmol/m²/s treatment. The photosynthetic rate increased(2.0-3.8 µmolCO²/m²/s) as the amount of light intensity increased, peaking at 120 µmol/m²/s, and then decreasing. The SPAD (chlorophyll content) value decreased as the amount of light intensity increased, and was the highest at 36.1 in fluorescent lamp treatment. Ginseng germination started on April 5 and took 14-17 days to germinate. The overall germination rate was 68.8-73.6%. The growth of aerial parts(plant height etc.) were generally excellent in the treatment of light intensity of 120-160 µmol/m²/s. The plant height was 41.9 cm, stem length was 24.1 cm, leaf length was 9.8 cm and stem diameter was 5.6 mm. The growth of underground part (root length etc.) was the best in the treatment with 120 µmol/m²/s of light intensity. Due to the root length was long(24.8 cm) and diameter of taproot was thick(18.7 mm), the fresh root weight was the heaviest at 24.8 g. There were no disease incidence such as Alternaria blight, Gray mold and Anthracnose. Disease of Damping-off caused by Rhizoctonia solani occurred 0.6-1.5% and incidence ratio of rusty root ginseng was 30.8-62.3%. It is believed that the reason for the high incidence of rusty root ginseng is that the amount of field moisture capacity of artificial bed soil is larger than the soil. Leaf discoloration rate was 13.7-32.3%.