• The Korean Journal of Ecology
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• v.23 no.4
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• pp.323-329
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• 2000

The allelopathic effects of volatile substances from Chamaecyparis obtusa (S. et Z.) Endl. were examined on the germination and seedling growth of some plant species, and on the population growth of some microorganisms. The germination and seedling growth of the receptor plants were suppressed more severely by leaf and fruit essential oils than by those of other parts. Colonial growth of fungi was severely inhibited by essential oils extracted from leaves and fruits. The development of root hairs of the receptor plants was also severely inhibited by the essential oils. The cortical cells at the root tips of Lactuca sativa L. treated with essential oils showed contraction of the cytoplasm, resulting in plasma membranes becoming detached from the cell walls and the cells metamorphosing irregularly. Accumulation of lipid granules inside the contracted cytoplasm and degeneration of mitochondrial cristae were also observed.

• Journal of Life Science
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• v.15 no.4 s.71
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• pp.673-677
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• 2005

This experiment was conducted to clarify the effect of pyroligneous liquor on endogenous substances that were GA (gibberelic acid)-like substances, starch, and protein of Neofinetia falcata cultured in vitro. When seedlings of Neofinetia falcata were treated with several concentrations (0, 0.5, 1.0, 2.0, 3.0 ml/L) of pyroligneous liquor, the growth of seedlings was enhanced in 1.0ml/L pyroligneous liquor added media. The activity of GA-like substances was lower in the leaf, but higher in the and root than that of the control. The content of starch in 1.0ml/L pyroligneous liquor was lower in the leaf, but higher in the root than that of the control. And the content of protein in 1.0ml/L pyroligneous liquor was also lower in the leaf, but higher in the root than that of the control.

• Korean Journal of Agricultural Science
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• v.11 no.2
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• pp.190-193
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• 1984

Extracts of common purslane(Portulaca oleracea L.) showed to possess some antifungal substances which inhibited the mycelial growth of the phytopathogenic fungi tested;Valsa mali, Alternaria kikuchiana and Pyricularia oryzae. These antifungal substances were found to be soluble in methanol and were regarded as kinds of lipid. In order to isolate the antifungal substances, the extracts of common purslane were concentrated by evaporation under reduced pressure and extracted with methanol The methanol solution was subjected to silica gel-florisil column and divided into lipid and non-lipid fractions. Lipid fractions only showed antifungal activity against the fungi tested. The effective substances contained in the extracts of common purslane inhibited not only the mycelial growth but also the spore germination of the fungi.

• The Plant Pathology Journal
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• v.38 no.1
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• pp.25-32
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• 2022

Plant pathogens pose major threats on agriculture and horticulture, causing significant economic loss worldwide. Due to the continuous and excessive use of synthetic pesticides, emergence of pesticide resistant pathogens has become more frequent. Thus, there is a growing needs for environmentally-friendly and selective antimicrobial agents with a novel mode of action, which may be used in combination with conventional pesticides to delay development of pesticide resistance. In this study, we evaluated the potentials of lichen substances as novel biopesticides against eight bacterial and twelve fungal plant pathogens that have historically caused significant phytopathological problems in South Korea. Eight lichen substances of diverse chemical origins were extracted from axenic culture or dried specimen, and further purified for comparative analysis of their antimicrobial properties. Usnic acid and vulpinic acid exhibited strong antibacterial activities against Clavibacter michiganensis subsp. michiganensis. In addition, usnic acid and vulpinic acid were highly effective in the growth inhibition of fungal pathogens, such as Diaporthe eres, D. actinidiae, and Sclerotinia sclerotiorum. Intriguingly, the growth of Rhizoctonia solani was specifically inhibited by lecanoric acid, indicating that lichen substances exhibit some degrees of selectivity to plant pathogens. These results suggested that lichen substance can be used as a selective biopesticide for controlling plant disease of agricultural and horticultural significance, minimizing possible emergence of pesticide resistant pathogens in fields.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.s01
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• pp.16-25
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• 1989

A bioassay is a test system using a living organism (in whole or in part) to determine the presence or relative potency of chemical substances. The development and uses of bioassay are intimately linked to the discovery and characterization of the major classes of plant hormones. An application of this relationship is helpful for understanding the concept of plant hormones as well as the use of bioassay. And plant bioassay have been development and employed not only for the discovery and characterization of the biological activity of plant growth regulators but also have served several important secondary roles. The ideal bioassay should possess the characteristic of high specificity. great sensitivity. short response time, low cost and ease of obtaining plant material. acceptable ease of manipulation, and minimal space and equipment requirements.

• ALGAE
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• v.31 no.3
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• pp.189-204
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• 2016

Microalgal bioremediation of CO₂, nutrients, endocrine disruptors, hydrocarbons, pesticides, and cyanide compounds have evaluated comprehensively. Microalgal mitigation of nutrients originated from municipal wastewaters, surface waters, and livestock wastewaters has shown great applicability. Algal utilization on secondary and tertiary treatment processes might provide unique and elegant solution on the removing of substances originated from various sources. Microalgae have displayed 3 growth regimes (autotrophic, heterotrophic, and mixotrophic) through which different organic and inorganic substances are being utilized for growth and production of different metabolites. There are still some technology challenges requiring innovative solutions. Strain selection investigation should be directed towards identification of algal that are extremophiles. Understanding and manipulation of metabolic pathways of algae will possible unfold solution to utilization of algae for mitigation of dissolve organic nitrogen in wastewaters.

• Journal of Plant Biology
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• v.32 no.1
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• pp.41-49
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• 1989

Phenolic compounds such as gallic acid, ferulic acid, p-hydroxybenzoic acid, vanillic acid, salicylic acid, tannic acid, and hydroquinone were identified from the aqueous extracts and volatile substances of tomato plant by paper chromatography, high performance liquid chromatography and gas chromatography. The seed germination and seedling growth of the experimental species, lettuce and egg plant, were severely inhibited in 5$\times$10-3M of phenolic reagents identical to those identified from tomato plant. Germination and growth rate of test species in 5$\times$10-4M and 5$\times$10-5M were higher than that of 5$\times$10-3M. Therefore, 5$\times$10-3M of phenolic compounds would be assumed to be threshold concentration for allelopathic effects.

• Journal of Microbiology and Biotechnology
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• v.4 no.4
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• pp.296-304
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• 1994

Antibiotic substances were produced by Bacillus subtilis YB-70, a potential biocontrol agent found to suppress root-rot of eggplant (Solanum melonggena L) caused by Fusarium solani, in a dextrose glutamate medium and isolated by isoelectric precipitation. Partial purification was performed by column chromatography on silica gel with two solvent systems: chloroform-methanol and methanol-chloroform-water as eluting solvents, This active fraction YBS-1 s contained antifungal activity were soluble in ethanol, methanol, and water, but were not soluble in other solvents including acetone, butanol, ethyl ether, dimethylformamide, propanol, and etc. High performance liquid chromatography and thin layer chromatographic separation of YBS-1s showed that they have been composed of three biological active bands that were named YBS-1A, -1B, and -1C. The substances were stable to heat and resistant to protease. YBS-1s were active against a wide range of plant pathogenic fungi but did not inhibit the growth of bacteria and yeasts. They were not only fungicidal but also fungistatic against chlamydospores of F. solani. The $ED_{50}$ values for the chlamydospore germination and the germ-tube growth of F. solani were $O.725\mu\textrm{m}/ml\;and\;O.562\mu\textrm{m}/ml$, respectively. Microscopic observations proved the substances restricted the growth of phytopathogenic fungus F. solani by spore burst followed by dissolving of its germ-tube, and caused abnormal hyphal swelling after application to chlamydospores or growing hyphae. Cultural filtrate of B; subtilis YB-70 also suppressed the development of root-rot of eggplant in pot tests.

• 대한치주과학회:학술대회논문집
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• 1994.12a
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• pp.9-9
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• 1994

• Journal of Plant Biotechnology
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• v.32 no.2
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• pp.139-144
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• 2005

This experiment was conducted to identify the effect of several plant growth retardants on endogenous ABA-like substance content and GA-like substance activity in seedlings of Sedirea japonica cultured in vitro. When seedlings of Sedirea japonica were treated with low concentration of 0.05 mg/L Uniconazole, 0.1 mg/L Ancymidol and 0.3 mg/L Paclobutrazol, the content of ABA-like substances of the leaf was lower than that of the control. However, the activity of GA-like substances was similar or higher in treated seedlings. In the mid and high concentrations of three kinds of growth retardants, the ABA-like substance content was increased, but GA-like substance activity was inhibited. The content of ABA-like substances in the root was lower in 0.05 and 0.2 mg/L Uniconazole, 0.2 mg/L Ancymidol and 0.1 mg/L Paclobutrazol treatments than that of the control, but in the mid and high concentration treatments, the content was increased. GA-like substance activity in low concentration was increased but in the mid and high concentration, the activity was inhibited compared with low concentration treatment.