• The Plant Pathology Journal
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• 제24권3호
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• pp.317-321
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• 2008

In a search for plant extracts with in vivo antifungal activity for plant diseases, we found that the methanol extract of Myristica malabarica fruit rinds effectively suppressed the development of several plant diseases. The methanol extract exhibited potent 1-day protective activity against rice blast, tomato late blight, wheat leaf rust and red pepper anthracnose. It also showed 7-day and 4-day protective activities against the plant diseases. Three antifungal resorcinols were isolated from the methanol extract of M. malabarica fruit rinds and identified as malabaricones A(MA), B(MB), and C(MC). Inhibitory activity of the three resorcinols against mycelial growth of plant pathogenic fungi varied according to compound and target species. All three compounds effectively reduced the development of rice blast, wheat leaf rust and red pepper anthracnose. In addition, MC was highly active for reducing the development of tomato late blight. This is the first report on the antifungal activities of malabaricones against filamentous fungi.

• The Plant Pathology Journal
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• 제31권3호
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• pp.278-289
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• 2015

Indigenous strains of Trichoderma species isolated from rhizosphere soils of Tea gardens of Assam, north eastern state of India were assessed for in vitro antagonism against two important tea fungal pathogens namely Pestalotia theae and Fusarium solani. A potent antagonist against both tea pathogenic fungi, designated as SDRLIN1, was selected and identified as Trichoderma viride. The strain also showed substantial antifungal activity against five standard phytopathogenic fungi. Culture filtrate collected from stationary growth phase of the antagonist demonstrated a significantly higher degree of inhibitory activity against all the test fungi, demonstrating the presence of an optimal blend of extracellular antifungal metabolites. Moreover, quantitative enzyme assay of exponential and stationary culture filtrates revealed that the activity of cellulase, ${\beta}$-1,3-glucanase, pectinase, and amylase was highest in the exponential phase, whereas the activity of proteases and chitinase was noted highest in the stationary phase. Morphological changes such as hyphal swelling and distortion were also observed in the fungal pathogen grown on potato dextrose agar containing stationary phase culture filtrate. Moreover, the antifungal activity of the filtrate was significantly reduced but not entirely after heat or proteinase K treatment, demonstrating substantial role of certain unknown thermostable antifungal compound(s) in the inhibitory activity.

• The Plant Pathology Journal
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• 제23권4호
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• pp.295-299
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• 2007

These experiments were carried out to examine efficacy of soil solarization for control of pink root disease by means of mulching with transparent polyethylene sheets in the hot season. The effects of soil solarization on incidence of pink-root disease caused by Pyrenochaeta terrestris and on onion growth and on populations of soil fungi were investigated. Solarization was dramatically effective in reducing pink root incidence in onion seedling and harvested onion bulb. A 30-day and 40-day solarization treatment significantly improved seedling survival and increased yield of 'Changnyeong-deago' onion while decreasing incidence of pink root. Populations of soil fungi from fields planted to onion were assayed on selective media. Solarization treatment was effective in reducing populations of P. terrestris, Pythium spp., and Rhizoctonia sp. in soil. Increase of yield of onion bulbs was associated with control of soil-borne pathogenic fungi. Soil solarization had beneficial effects on yield, bulb diameter, or incidence of pink root.

• Mycobiology
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• 제34권4호
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• pp.185-190
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• 2006

Endophytic fungi were isolated from healthy leaf and root samples of Taraxacum coreanum. Of the 72 isolates recovered, 39 were from leaves and 33 from roots with an isolation frequency of 54% and 46%, respectively. Based on ITS sequence analysis, 72 isolates were classified into 19 genera of which 17 were under the phylum Ascomycota and 2 were under Basidiomycota. Diverse genera were found and Alternaria, Cladosporium, Fusarium and Phoma were dominant. Out of 19 genera, Apodus, Ceriporia, Dothideales, Leptodontidium, Nemania, Neoplaconema, Phaeosphaeria, Plectosphaerella and Terfezia were new to Korea. Seventy two isolates were screened for antifungal activity, of which 10 isolates (14%) were found active at least against one of the tested fungi. Isolate 050603 had the widest antifungal spectra of activity, and isolates 050592 and 050611 were active against three plant pathogenic fungi.

• 한국환경농학회지
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• 제21권3호
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• pp.216-222
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• 2002

항진균 세균의 특성 및 기능변화 가능성을 조사하기 위하여 버섯폐배지, 온천수, 해조류 및 삼림토양으로부터 식물병원성 진균에 대한 8종의 항진균 활성 균주를 분리하였고 감마선($^{60}Co$)을 이용하여 $LD_{95}$에서 돌연변이체를 유도하였다. Bacillus circulans K1, Burkholderia gladioli K4와 Bacillus subtilis YS1은 12 종의 식물병원성 진균에 대해 항진균 활성을 보였다. 이들 균주의 방사선감수성 조사결과 B. gladioli K4는 감마선에 대한 높은 감수성을 보였으며, $D_{10}$ 값은 0.11 kGy 였다. 감마선에 의해 유도된 K1-1004와 YS1-1009는 Botryosphaeria dothidea에 대해 항진균 활성이 증가되었다. B. subtilis YS1의 돌연변이체인 YS1-1006과 YS1-1009는 tebuconazol과 copper hydroxide에 대해 농약 저항성을 나타냈다. SAR535, SAR5108 과 SAR5l18 돌연변이체는 야생형 균주인 Streptomyces sp. SAR01에 비해 5 종의 식물병원성 진균에 대해 항진균 활성이 없었다. 연구결과, 방사선을 이용하여 다양한 기능의 돌연변이체 유도가 가능하였다. 이를 이용하여 항진균 활성 관련 유전자 연구 및 균주개량이 가능할 것으로 사료된다.

• Mycobiology
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• 제48권5호
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• pp.392-398
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• 2020

This study was conducted to understand the dynamics of microbial communities of soil microorganisms, and their distribution and abundance in the indigenous microorganisms (IMOs) manipulated from humus collected from the forest near the crop field. The soil microorganisms originated from humus and artificially cultured microbial-based soil amendments were characterized by molecular and biochemical analyses. The bacterial population (2 × 10⁶~13 × 10⁶ CFU/g sample) was approximately 100-fold abundant than the fungal population (2 × 10⁴~8 × 10⁴ CFU/g sample). The 16S rDNA and ITS sequence analyses showed that the bacterial and fungal communities in humus and IMOs were mainly composed of Bacillus and Pseudomonas, and Trichoderma and Aspergillus species, respectively. Some of the bacterial isolates from the humus and IMOs showed strong inhibitory activity against soil-borne pathogenic fungi Fusarium oxysporum and Sclerotinia sclerotiorum. These bacteria also showed the siderophore production activity as well as phosphate solubilizing activity, which are requisite traits for biological control of plant pathogenic fungi. These results suggest that humus and IMOs could be a useful resource for sustainable agriculture.

• The Plant Pathology Journal
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• 제27권2호
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• pp.103-109
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• 2011

The fungal genus Cercospora is one of the most ubiquitous groups of plant pathogenic fungi, and gray leaf spot caused by C. zeae-maydis is one of the most widespread and damaging foliar diseases of maize in the world. While light has been implicated as a critical environmental regulator of pathogenesis in C. zeae-maydis, the relationship between light and the development of disease is not fully understood. Recent discoveries have provided new insights into how light influences pathogenesis and morphogenesis in C. zeae-maydis, particularly at the molecular level. This review is focused on integrating old and new information to provide an updated perspective of how light influences pathogenesis, and provides a working model to explain some of the underlying molecular mechanisms. Ultimately, a thorough molecular-level understanding of how light regulates pathogenesis will augment efforts to manage gray leaf spot by improving host resistance and disease management strategies.

• 한국식물병리학회지
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• 제11권2호
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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.

• The Plant Pathology Journal
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• 제24권1호
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• pp.24-30
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• 2008

Colletotrichum gloeosporioides forms an appressorium, a specialized infection structure, to infect its hosts. Among 400 and 600 culture filtrates from fungi and class Actinomycetes, six methanol extracts (A5005, A5314, A5387, A5560, A5597, and A5598) from the class Actinomycetes significantly inhibited appressorium formation in C. gloeosporioides infecting pepper fruits in a dose-dependent manner, while conidial germination was slightly enhanced. Two (A5005 and A5560) of them also exhibited distinctive inhibitory effect on the disease progress of pepper anthracnose. Water fractions of both culture filtrates also specifically inhibited appressorium formation in C. gloeosporioides and pepper anthracnose disease. Inhibition of appressorium formation by culture filtrate of A5005 was partially restored by the exogenous calcium. This results suggests that chemicals within A5005 extents its biological activity through disturbance of intracellular $Ca^{2+}$ regulation during prepenetration morphogenesis by C. gloeosporioides. Together, cell-based and target-oriented screening system used in this study should be applicable for other plant pathogenic fungi prerequisite appressorium formation to infect their hosts.

• 한국환경농학회지
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• 제29권1호
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• pp.86-91
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• 2010

This study was carried out to assess the antifungal potential of R. oligosporus and its ethyl acetate (EtOAc) extract against the fungal pathogens causing anthracnose disease in apple fruits using disc diffusion, antagonistic effect and morphological abnormalities in fungal mycelia. The percentage of inhibition of antifungal effect of the ethyl acetate extract (5 ${\mu}l$ $disc^{-1}$) of the R. oligosporus against C. acutatum KACC 40848, C. gloeosporioides KACC 40897, C. higginsianum KACC 40806, C. orbiculare KACC 40808, C. coccodes KACC 40008, C. musae KACC 40947, C. boninense KACC 40893, C. liliacearum KACC 40981, C. caudatum KACC 41028 and Colletotrichum sp. KACC 40811 was found to be 44.4, 35.5, 40, 31.1, 33.3, 37.7, 40, 51.1, 28.8 and 28.8%, respectively. Also the fungus R. oligosporus showed potential antagonistic effect of antifungal activity against the tested pathogens of Colletotrichum spp. Further, R. oligosporus had a potential detrimental effect on the morphology of the tested fungi of Colletotrichum spp. such as wrinkle abnormalities, abnormal cell formation, lysis of mycelium, empty cell formation, distorted cell formation and breakage of the mycelium. These findings strongly support the role of R. oligosporus to serve as a potential antifungal agent to control plant pathogenic fungi causing anthracnose disease in apple fruits.