• Korean Journal of Environmental Agriculture
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• v.35 no.3
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• pp.191-201
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• 2016

BACKGROUND: The aim of this study was to investigate the antimicrobial effects of the ethanol extracts from various medicinal herbs against plant pathogens to understand the possible the crop protection agents.METHODS AND RESULTS: Among the tested medicinal herbs, Zizyphus jujuba ethanol extract had the potent antimicrobial activity against Phytophthora capsici, Erwinia carotovorum subsp. carotovora, Pseudomonas syringae pv. syringae and Ralstonia solanacearum. The major constituents of Z. jujuba were identified to eugenol(40.45%), dodecanoic acid(18.40%), β-caryophyllene (10.05%) and isoeugenol(9.85%) by GC/MS. Eugenol and isoeugenol had strong inhibitory activity on spore germination against P. capsici and growth against E. carotovorum subsp. carotovora, P. syringae pv. syringae and R. solanacearum.CONCLUSION: In this regard, eugenol and isoeugenol were found to be responsible for the antimicrobial activity of Z. jujuba ethanol extract against plant pathogens. In addition, Z. jujuba ethanol extract, eugenol and isoeugenol can be used the potent antimicrobial agents.

• Journal of Life Science
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• v.18 no.7
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• pp.974-979
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• 2008

The powdery mildew, a fungal plant disease found in varieties of plant cultures, is occurred by attack with Fusarium sp., Sphaerotheca sp., Leveilluna sp., and Eryshipe sp.. In this study we investigated the control of Fusarium graminearum, a barley powdery mildew fungus, by natural plant extracts. Among the 900 plant extracts tested, Zanthoxylum schinifolium, Ligusticum acutilobum, Bidens frondosa L., Dictamnus dasycarpus, Evodia officinalis, Disporum sessile, Scopolia japonica Max., Styrax japonica S. et Z., Dictamnus dasycarpus Turcz., Sinomenium acutum Rehder et Wils., Eugenia aromaticum, Rubus parvifolius L., Reynoutria elliptica, Coptis chinensis, Paeonia lactiflora Pall., Rheum undalatum, Paeonia suffruticosa, Oenothera odorata Jacq., Euphorbia pekinensis Rupr., and Nepeta cataria were selected based on spore germination inhibition assay. Further mycelial growth inhibition assay with economical and safety considerations led us to finally select Z. schinifolium (sancho) for control of F. graminearum. To produce antifungal sancho extract, methanol was suitable for extraction and subsequent fractionations of the extract showed that the water residue mainly had antifungal activity. The sancho extract and its fractions showed minor antibacterial activity against different pathogenic or food spoilage bacteria, but they did not show any harmful effects against young tomato plant by treatment of $1,000\;{\mu}g/ml$ in green chamber test. These results suggested that the extract of sancho has high potentials on control of a powdery mildew fungus, F. graminearum.

• Korean Journal of Organic Agriculture
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• v.23 no.2
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• pp.347-357
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• 2015

This experiment was conducted to test the efficiency of environmentally friendly materials for controlling garlic leaf blight by Stemphylium botryosum. Fifty five kinds of environmental friendly control agents are obtained from commercial market and are tested for spore germination using 96 well plate and among them, five agents (copper-, sulfur-, medinal herb extract-, sulfur+sodium bicarbonate- and oligo chitosan based compound) are selected for field test from 2012 and 2013 year. With reference of 2012 year test result, copper and oligo chitosan based compounds are chosen as 2013 year test. When the first symptoms were appeared early May season and environmental friendly control agents are applied as prompt as possible, the control value of copper and oligo chitosan based agents are 54% and 90% respectively as compared to the occasion of chemical agent Antracol WP (propineb 70%) and yield of bulbs are increased by 16% and 34% against untreated control and marketable garlic bulb yield were 79% and 95% against Antracol WP treatment, respectively. From this result, oligo chitosan based compound can be a good organic control agent candidate for garlic leaf blight disease in organic garlic cultivation.

• Research in Plant Disease
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• v.23 no.3
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• pp.268-277
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• 2017

Fusarium head bight (FHB) is a devastating disease on major cereal crops worldwide which causes primarily by Fusarium graminearum. Synthetic fungicides are generally used in conventional agriculture to control FHB. Their prolonged usage has led to environmental issues and human health problems. This has prompted interest in developing environmentally friendly biofungicides, including botanical fungicides. In this study, a total 100 plant extracts were tested for antifungal activity against F. graminearum. The crude extract of Pterocarpus santalinus heartwood showed the strongest antifungal activity and contained two antifungal metabolites which were identified as ${\alpha}$-cedrol and widdrol by GC-MS analysis. ${\alpha}$-Cedrol and widdrol isolated from P. santalinus heartwood extract had 31.25 mg/l and 125 mg/l of minimal inhibitory concentration against the spore germination of F. graminearum, and also showed broad spectrum antifungal activities against various plant pathogens. In addition, the wettable powder type formulation of heartwood extract of P. santalinus decreased FHB incidence in dose-dependent manner and suppressed the development of FHB with control values of 87.2% at 250-fold dilution, similar to that of chemical fungicide (92.6% at 2,000-fold dilution). This study suggests that the heartwood extract of P. santalinus could be used as an effective biofungicide for the control of FHB.

• Journal of Mushroom
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• v.11 no.1
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• pp.1-8
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• 2013

In this study, twelve of Lepista nuda were collected from various localities in Korea. Also thirteen exotic L. nuda species were collected from Japan, France, Switzerland and Portugal. Spores were isolated under optical microscope. These spores were placed on the surface of YM medium for inducing to germination. Eleven mating-groups were selected by morphological characters of fruit body such as size, color and stipe patterns. Intra-isolate crosses were made between two single-spore isolates derived from mating-groups. Also, dikaryotic crossing using the isolates from L. nuda were carried out to evaluated tetrakaryon formation. Cross-mating compatibility tests also verified its dikaryotic state by microscopic or molecular genetic observation of clamp connection and Random Amplified Polymorphic DNA (RAPD) band pattern. To analyze the growth rate of hybrids and parents mycelium in dikaryons obtained from compatible mating groups were placed on PDA medium. Intra-isolate crosses determined eleven mating-groups within L. nuda. The typical clamp connection were mostly observed in mating-groups of Korean L. nuda in $K1{\times}K2$, $K1{\times}K3$, $K1{\times}K4$, $K1{\times}K6$, $K1{\times}K5$, $K2{\times}K4$, $K2{\times}K3$, $K2{\times}K6$, $K3{\times}K4$, $K4{\times}K5$, and $K4{\times}K6$. Korean L. nuda type of dikaryon, shown to cross-incompatibility with L. sordida, it seemed that mating induce more rapidly than wild types in a view of growth rate. In conclusion, it would be useful to improve mass production with better morphological characteristics through a special mating of L. nuda.

• The Plant Pathology Journal
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• v.25 no.4
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• pp.344-351
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• 2009

A biocontrol bacterium Bacillus licheniformis N1 grown in nutrient broth showed no chitinolytic activity, while its genome contains a gene which encodes a chitinase. The gene for chitinase from B. licheniformis N1 was amplified by PCR and the deduced amino acid sequence analysis revealed that the chitinase exhibited over 95% identity with chitinases from other B. licheniformis strains. Escherichia coli cells carrying the recombinant plasmid displayed chitinase activity as revealed by the formation of a clear zone on chitin containing media, indicating that the gene could be expressed in E. coli cells. Chitinase gene expression in B. licheniformis N1 was not detected by RT-PCR analysis. The protein was over-expressed in E. coli BL21 (DE3) as a glutathione S-transferase fusion protein. The protein could also be produced in B. subtilis 168 strain carrying the chitinase gene of N1 strain. The crude protein extract from E. coli BL21 carrying GST fusion protein or culture supernatant of B. subtilis carrying the chitinase gene exhibited enzyme activity by hydrolyzing chitin analogs, 4-methylumbelliferyl-$\beta$-D-N,N'-diacetylchitobioside and 4-methylumbelliferyl-$\beta$-D-N,N',N"-triacetylchitotrioside. These results indicated that even though the chitinase gene is not expressed in the N1 strain, the coding region is functional and encodes an active chitinase enzyme. Furthermore, B. subtilis 168 transformants expressing the chitinase gene exhibited antifungal activity against Fulvia fulva by suppressing spore germination. Our results suggest that the proper engineering of the expression of the indigenous chitinase gene, which will lead to its expression in the biocontrol strain B. licheniformis N1, may further enhance its biocontrol activity.

• Microbiology and Biotechnology Letters
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• v.27 no.6
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• pp.427-432
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• 1999

For the development of a multifunctional biocontrol agent, the siderophore-producing strain GL7 was isolated from a rhizosphere on chrome azurol S agar. The GL7 was identified as a strain of Pseudomonas fluorescents on the basis of their reactions to standard physicochemcial tests from Bergey's manual, API diagnostic test, and fatty acid analysis. P. fluorescents GL7 considerably inhibited spore germination and hyphal growth of phytopathogenic fungus Funsarium solani in a dual culture. In pot trials of bean with P. fluorescens GL7, the disease incidence was significantly reduced down to 5% from 70% of incidence in the untreated control. P. fluorescens GL7 also enhanced plant growth to nearly 1.5 times than that of the untreated control, promoting elongation and development of the roots. These results suggest that the plant growth-promoting P. fluorescens GL7 can play an important role in the biological control of soil-borne plant disease in a rhizosphere.

• The Korean Journal of Pesticide Science
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• v.12 no.3
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• pp.291-294
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• 2008

The Streptomyces padanus isolate TH04, isolated from mummified peaches, showed strong antifungal activity to Monilinia fructicola. The inhibition activity of the isolate TH04 to mycelial growth and spore germination at 1% concentration of sub-antifungal powder made from culture suspension (CS) was ranged from 79.8% to 81.0% and from 73.9% to 75.8% to M. fructicola four strains, respectively. In the test of antifungal activity in mixed culture of the isolate and M. fructicola, inhibition rate was 7.5%, 86.8% and 94.0% in 0.01, 0.1, and 1% concentration of CS containing bacterial cell of the isolate, respectively. On apples (cultivar; Fuji), the control values of the isolate TH04 crude filtrates (0.1 and 1%) were 85.9% and 100%, respectively. The results suggest that the isolate TH04 indicate development possibility as biocontrol agent of brown rot caused by M. fructicola with the study on delivery method and fermentation condition to produce an antifungal compound.

• Microbiology and Biotechnology Letters
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• v.39 no.2
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• pp.168-174
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• 2011

In order to develop safe and economic novel antifungal agents, we prepared 73 methanol extracts from medicinal and edible herbs and examined their 365 solvent fractions using n-hexane, methylene chloride, ethylacetate, butanol and water residue based on the sequential organic solvent fraction method. When using the various fractions in the screening step for antifungal activity, we discovered ethylacetate fraction of Morus alba L., methylene chloride fraction of Pimpinella brachycarpa (MCPB), and n-hexane fraction of Salvia miltiorrhiza Bunge, which all have activities in methanol extracts, as potential sources of antifungal agents. Amongst these, the antifungal activity of P. brachycarpa has not to date been reported on. In addition, the mycelial growth inhibition and spore germination inhibition activities of MCPB against A. niger were confirmed by disc-diffusion assay in a 10 day culture. The MIC and MFC of MCPB were determined as 0.25 and 0.5 mg/ml, respectively. The MCPB has no hemolytic activity against human RBC at 0.5 mg/ml and glycoside-flavonoids are theorized to be active constituents. These results suggest that MCPB has a prominent antifungal activity and that the application of sequential organic solvent fractions, instead of simple natural product extracts, is useful in the screening process of novel bioactive substances.

• The Korean Journal of Pesticide Science
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• v.15 no.2
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• pp.188-193
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• 2011

Resistance monitoring for tolyfluanid was conducted over 2 years from 2005 to 2006 with 218 isolates of Botrytis cinerea obtained from infected plants of ginseng. All isolates of B. cinerea were divided into 3 groups such as highly sensitive (HS) group, sensitive (S) group and less sensitive (LS) group to tolyfluanid. HS group was defined as one showing $EC_{50}$ value less than $2.0\;{\mu}g\;mL^{-1}$. $EC_{50}$ value of S group ranged between $2.0\;{\mu}g\;mL^{-1}$ and $18.0\;{\mu}g\;mL^{-1}$, while that of LS group was more than $18.0\;{\mu}g\;mL^{-1}$ Among B. cinerea isolates tested in this study, 174 isolates were included into S group, while 22 isolates were done into HS group. The other isolates belonged to LS group. Botrytis cinerea isolates showed the high correlation of $EC_{50}$ value of mycelial growth with that of spore germination to tolyfluanid. This results could be used for the determination of fungicide resistance and the establishment of strategy for fungicide resistance management.