• Applied Biological Chemistry
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• v.41 no.8
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• pp.600-604
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• 1998

Methanol extracts from 53 species of oriental medicinal plants in 34 families were tested for their fungicidal activities against Pyricularia grisea, Rhizoctonia solani, Phytophthora capsici, Phytophthora infestans, Collectotrichum dematium, Botryospaeria dothidea, Fusarium oxysporum f. sp. cucumerinum, Botrytis cinerea, Puccinia recondita, and Erysiphe graminis. In in vitro study using impregnated paper disc method, the efficacy varied with both plant pathogen and plant species tested. Methanol extracts of Asarum sieboldii roots, Sinomenium acutum roots, Pinus densiflora leaves, Rheum undulatum root barks, Coptis japonica roots, and Phellodendron amurense barks showed potent fungicidal activities against the various pathogens when treated with 10 mg/disc. In a whole plant test, methanol extracts of P. densiflora leaves and roots and C. japonica roots were highly effective against a variety of plant pathogens. As a naturally occurring fungicide, P. densiflora- and C. japonica-derived materials could be useful as new fungicidal products against various plant diseases induced by plant pathogenic fungi.

• 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.

• Proceedings of the Botanical Society of Korea Conference
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• 1999.07a
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• pp.41-44
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• 1999

Magnaporthe grisea (Hebert) Barr (anamorph: Pyricularia grisea) is a typical heterothallic Ascomycete and the causal agent of rice blast, one of the most destructive diseases on rice (Oryza sativa L.) worldwide. The interactions between cells of the pathogen and those of the host involve a complex of biological influences which can lead to blast disease. The early stages of infection process in particular may be viewed as a sequence of discrete and critical events. These include conidial attachment, gemination, and the formation of an appressorium, a dome-shaped and melanized infection structure. Disruption of this process at any point will result in failure of the pathogen to colonize host tissues. This may offer a new avenue for developing innovative crop protection strategies. To recognize and capture such opportunities, understanding the very bases of the pathogenesis at the cellular and molecular level is prerequisite. Much has been learned about environmental cues and endogenous signaling systems for the early infection-related morphogenesis in M. grisea during last several years. The study of signal transduction system in phytopathogenic filamentous fungi offers distinct advantages over traditional mammalian systems. Mammalian systems often contain multiple copies of important genes active in the same tissue under the same physiological processes. Functional redundancy, alternate gene splicing, and specilized isoforms make defining the role of any single gene difficult. Fungi and animals are closely related kingdoms [3], so inferences between these organisms are often justified. For many genes, fungi frequently possess only a single copy, thus phenotype can be attributed directly to the mutation or deletion of any particular gene of interest.

• Proceedings of the Botanical Society of Korea Conference
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• 1985.08b
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• pp.19-22
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• 1985

Magnaporthe grisea (Hebert) Barr (anamorph: Pyricularia grisea) is a typical heterothallic Ascomycete and the causal agent of rice blast, one of the most destructive diseases on rice (Oryza sativa L.) worldwide. The interactions between cells of the pathogen and those of the host involve a complex of biological influences which can lead to blast disease. The early stages of infection process in particular may be viewed as a sequence of discrete and critical events. These include conidial attachment, gemination, and the formation of an appressorium, a dome-shaped and melanized infection structure. Disruption of this process at any point will result in failure of the pathogen to colonize host tissues. This may offer a new avenue for developing innovative crop protection strategies. To recognize and capture such opportunities, understanding the very bases of the pathogenesis at the cellular and molecular level is prerequisite. Much has been learned about environmental cues and endogenous signaling systems for the early infection-related morphogenesis in M. grisea during last several years. The study of signal transduction system in phytopathogenic filamentous fungi offers distinct advantages over traditional mammalian systems. Mammalian systems often contain multiple copies of important genes active in the same tissue under the same physiological processes. Functional redundancy, alternate gene splicing, and specilized isoforms make defining the role of any single gene difficult. Fungi and animals are closely related kingdoms [3], so inferences between these organisms are often justified. For many genes, fungi frequently possess only a single copy, thus phenotype can be attributed directly to the mutation or deletion of any particular gene of interest.

• 한국균학회소식:학술대회논문집
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• 2014.10a
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• pp.49-49
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• 2014

In order to find indigenous beneficial fungal species from crop field soils of Nigeria, 23 soil samples were collected from various places of Nigeria in June, 2013 and fungi were isolated through serial dilution technique. Isolated fungi were purified and differentiated according to their morphological and microscopic characteristics. In total, 38 different representative isolates were recovered and the genomic DNA of each isolates was extracted using QIAGEN$^{(R)}$ Plasmid Mini Kit (QIAGEN Sciences, USA) and the identification of fungi was carried out by sequence analysis of internal transcribed spacer (ITS) region of the 18S ribosomal DNA (18S rDNA). Recovered isolates belonged to 9 fungal genera comprising Fusarium, Aspergillus, Chaetomium, Coniothyrium, Dipodascaceae, Myrothecium, Neosartorya, Penicillium and Trichoderma. Aspergillus spp., Penicillium spp. and Trichoderma spp. were the most dominant taxa in this study. The antagonistic potentiality of species belonged to Trichoderma against 10 phytopathogenic fungi (F. oxysporum, C. gloesporoides, P. cytrophthora, A. alternata, A. solani, S. rolfsii, F. solani, R. solani, S. sclerotiorum and P. nicotiana) was assessed in vitro using dual culture assay. The dual culture assay results showed varied degree of antagonism against the tested phytopathogens. The potential Trichoderma spp. will be further evaluated for their antagonistic and plant growth promotion potentiality under in vivo conditions.

• The Korean Journal of Mycology
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• v.47 no.3
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• pp.259-269
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• 2019

Brown spot and sheath rot of rice are caused by fungal pathogens such as Curvularia lunata, Cochliobolus miyabeanus, and Sarocladium oryzae, and cause losses such as reduced rice yield and quality, which is an enormous problem with serious long-term effects. To search biological control agents of phytopathogenic fungi, five kinds of useful Bacillus-like isolates which are excellent in extracellular enzyme activity and produce siderophore were selected from paddy soil of Sunchang in Korea. The selected isolates were tested for excellent antifungal activity against three of the phytopathogenic fungi that frequently occur in rice, and JSRB 177 strain had the most excellent antifungal activity. Based on the experimental results, JSRB 177 is finally selected as a candidate for biological control and identified to Bacillus subtilis through 16S rRNA sequence analysis. In addition, physiological characteristics of JSRB 177 confirmed by analysis of carbohydrate fermentation patterns and enzyme production ability. Based on the above results, JSRB 177 is expected to be used as a biological control agent for the rice pathogenic fungi. In the future, further studies related to industrialization such as port test and establishment of mass production process are needed.

• Microbiology and Biotechnology Letters
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• v.49 no.3
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• pp.403-412
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• 2021

This study aimed to identify plant growth-promoting activity, phytopathogenic fungi growth inhibitory activity, mineral solubilization ability, and extracellular enzyme activity of the genus Bacillus in soil and the rhizosphere. With regards to antifungal activity against phytopathogenic fungi, DDP257 showed antifungal activity against all 10 pathogenic fungi tested. ANG20 showed the highest ability to produce indole-3-acetic acid, a plant growth-promoting factor (70.97 ㎍/ml). In addition, 10 species were identified to have 1-aminocyclopropane-1-carboxylate deaminase production ability, and most isolates showed nitrogen fixation and siderophore production abilities. Thereafter, the isolated strains' ability to solubilize minerals such as phosphate, calcite, and zinc was identified. With extracellular enzyme activity, the activity appeared in most enzymes. In particular, all the strains showed similar abilities for alkaline phosphatase, esterase (C4), acid phosphatase, and naphtol-AS-BI-phosphohydrolase production. This result was observed because the genus Bacillus secreted various organic substances, antibiotics, and extracellular enzymes. Therefore, through the results of this study, we suggest the possibility of using strains contributing to the improvement of the soil environment as microbial agents.

• Korean Journal Plant Pathology
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• v.10 no.3
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• pp.151-156
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• 1994

Pseudomonas fluorescens produces the antibiotic, 2,4-diacetylphloroglucinol (Phl), which promotes plant growth by inhibiting bacteria and fungi. Cosmids (genomic library) were mobilized into Phl-nonproducing mutants through the triparental matings with pRK2013 as the helper plasmid at the frequency of 8.37$\times$10-4. Complemented mutants that showed antibiotic activity were selected among about 2,000 transconjugants. The complemented mutants were confirmed by acquired drug resistances (kanamycin and tetracycline). The antibiotic substances of wild type and complemented mutants showed the most excellent anti-bacterial activity. Inhibitory effects of complemented P. fluorescens against phytopathogenic fungi were equal to the parental strain. Complemented mutant and wild type of P. fluorescens were causal microbes of fungal morphological abnormalities. Complemented mutants in potato dextrose agar supplemented with bromothymol blue also showed restoration of glucose utilization as wild type. Plasmids of complemented mutants were isolated from transconjugant sand transformed into competent cells of E. coli DH5$\alpha$. The plamid DNA was reisolated from transformed E. coli DH5$\alpha$.

• Journal of Microbiology and Biotechnology
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• v.16 no.3
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• pp.465-468
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• 2006

Even though many pesticides are known for barley powdery mildew and wheat leaf rust, alternative controls are necessary, because of consumer rejection of chemical pesticides and the appearance of fungi resistant to fungicides. To discover biopesticides, many broths of microorganisms were screened. Of those, a culture broth of Burkholderia ambifaria showed an excellent antifungal activity against both Erysiphe graminis and Puccinia recondita, which cause barley powdery mildew and wheat leaf rust, respectively.

• Korean Journal Plant Pathology
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• v.11 no.2
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• pp.165-172
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• 1995

벼 잎집무늬마름병균(Rhizoctonia solani)의 균핵에서 분리한 길항세균 SJ-2를 대치 배양 방법에 의해 벼도열병균(Pyricularia oryzae)외 6종의 식물 병원균에 대한 억제 효과를 조사하였다. 형태 및 생리적 특성을 조사한 결과, 이 균은 Bacillus subtilis로 동정되었다. 이 균은 AM 1(antibiotic medium 1)액체 배지에서 항균 물질을 분비하였으며, 배양 2일째 가장 항균 활성이 높았다. Butyl alcohol로 배양액에서 항균 물질을 조추출하여 100$\mu\textrm{g}$/ml의 농도로 조제한 감자 한천 배지에서 P. oryzae의 15개균에 대한 생육을 조사한 결과 P. oryzae, R. solani, Cochliobolus sativus에 대해서는 100% 생장을 억제하였으며, C. miyabeanus, Alternaria alternata, Botrytis cinerea, Cladosporium fulvum, Colletotrichum gloeosporioides, Fusarium moniliforme, F. oxysporum에는 80% 이상의 억제 효과를 보인 반면 난균강에 속하는 병원균에 대한 효과는 낮게 나타났다. 활성물질을 분리 정제하여 동정한 결과 B. subtilis가 분비하는 항균 물질로 알려진 polypeptides계의 iturins로 밝혀졌다. 이러한 항균 물질은 벼 도열병균(P. oryzae)의 포자 발아 및 발아관의 팽대(swelling)를 야기했으며, 벼 잎집무늬마름병균(R. solani)에는 균사의 용균(lysis)현상을 일으켰다.