• Journal of Microbiology and Biotechnology
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• 제15권1호
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• pp.112-117
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• 2005

Abstract Griseofulvin has been used as an antifungal antibiotic for the treatment of mycotic diseases of humans and veterinary animals. The purpose of this work was to identify a griseofulvin-producing endophytic fungus from Abies holophylla and evaluate its in vivo antifungal activity against plant pathogenic fungi. Based on nuclear ribosomal ITS1-5.8SITS2 sequence analysis, the fungus was identified and labeled as Xylaria sp. F0010. Two antifungal substances were purified from liquid cultures of Xylaria sp. F0010, and their chemical identities were determined to be griseofulvin and dechlorogriseofulvin through mass and NMR spectral analyses. Compared to dechlorogriseofulvin, griseofulvin showed high in vivo and in vitro antifungal activity, and effectively controlled the development of rice blast (Magnaporthe grisea), rice sheath blight (Corticium sasaki), wheat leaf rust (Puccinia recondita), and barley powdery mildew (Blumeria graminis f. sp. hordei), at doses of 50 to 150 ${\mu}$g/ml, depending on the disease. This is the first report on the production of griseofulvin and dechlorogriseofulvin by Xylaria species.

• 농약과학회지
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• 제10권3호
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• pp.201-209
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• 2006

43종의 식물오일들을 대상으로 잿빛곰팡이병균 (Botrytis cinerea) 외 9종의 식물병원균에 대한 살균 효과로 이들의 생리활성 검증을 실시하였다. 이 중 thyme 오일이 잿빛곰팡이병균(Botrytis cinerea), 잎집무늬 마름병균(Rhizoctonia solani), 고추역병균(Phytophthora capsici), 고추탄저병균(Glomerella cingulate), 사과점무늬 낙엽병균(Alternaria mali)과 벼도열병균(Magnaporthe grisea)에서 광범위하게 살균효과를 나타내었다. Thyme 오일의 주성분을 GC/MS로 분석한 결과 thymol, carvacrol, borneol, linalool과 p-cymene임을 확인하였다. 이 중 thymol과 carvacrol이 높은 살균활성을 나타내었다. 한편, 식물병원균에 대한 살균활성관련 작용기작을 실험한 결과, 잿빛곰팡이병균(Botrytis cinerea), 잎집무늬마름병균(Rhizoctonia solani)과 사과점무늬낙엽병균(Alternaria mali)의 포자발아를 억제하는 것으로 나타났다. Thymol과 carvacrol은 in vivo에서 잿빛곰팡이병균(Botrytis cinerea)과 잎집무늬마름병균(Rhizoctonia solani)에 대하여 높은 예방효과를 나타내었으며, thymol, carvacrol의 유사구조를 갖는 alkylphenol계 화합물들도 살균활성이 있음을 검정하였다.

• 농약과학회지
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• 제10권3호
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• pp.165-171
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• 2006

2-이미노-1,3-티아졸린 유도체의 분자수정에 의하여 새로운 3-아미노-2-벤질이미노-1,3-티아졸린 화합물 라이브러리를 parallel 합성법에 의해서 합성하고, 대표적인 식물병 6종에 대한 살균력(100 ppm)을 조사하였다. 이들 유도체의 특징은 2-이미노-1,3-티아졸린 골격의 2위치의 이미노기에 벤질기가 3위치에 아미노기가 각각 치환된 것이다. 합성된 화합물 중 일부가 토마토 역병과 벼 도열병에 대하여 선택적인 살균 활성을 나타냈다. 살균력은 벤질기의 3,4-디클로로페닐기에서 기인한 것으로 생각된다.

• The Plant Pathology Journal
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• 제28권4호
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• pp.364-372
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• 2012

Xanthomonas oryzae pv. oryzae causing bacterial leaf blight disease in rice produces and secretes Hpa1 protein that belongs to harpin protein family. Previously it was reported that Hpa1 induced defense responses when it was produced in tobacco. In this study, we expressed hpa1 gene in rice and Arabidopsis to examine the effects of Hpa1 expression on disease resistance to both fungal and bacterial pathogens. Expression of hpa1 gene in rice enhanced disease resistance to both X. oryzae pv. oryzae and Magnaporthe grisea. Interestingly, individual transgenic rice plants could be divided into four groups, depending on responses to both pathogens. hpa1 expression in Arabidopsis also enhanced disease resistance to both Botrytis cineria and Xanthomonas campestris pv. campestris. To examine genes that are up-regulated in the transgenic rice plants after inoculation with X. oryzae pv. oryzae, known defense-related genes were assessed, and also microarray analysis with the Rice 5 K DNA chip was performed. Interestingly, expression of OsACS1 gene, which was found as the gene that showed the highest induction, was induced earlier and stronger than that in the wild type plant. These results indicate that hpa1 expression in the diverse plant species, including monocot and dicot, can enhance disease resistance to both fungal and bacterial plant pathogens.

• Mycobiology
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• 제31권3호
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• pp.179-182
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• 2003

A total of 187 endophytic fungi were isolated from 11 plant species, which were collected from 11 locations in Korea. Their antifungal activities were screened in vivo by antifungal bioassays after they were cultured in potato dextrose broth and rice solid media. Antifungal activity against plant pathogenic fungi such as Magnaporthe grisea(rice blast), Corticium sasaki(rice sheath blight), Botrytis cinerea(tomato gray mold), Phytophthora infestans(tomato late blight), Puccinia recondita(wheat leaf rust), and Blumeria graminis f. sp. hordei(barley powdery mildew) was determined in vivo by observing the inhibition of plant disease development. Twenty(11.7%) endophytic fungi fermentation broths were able to control, by more than 90%, at least one of the six plant diseases tested. Among 187 liquid broths, the F0010 strain isolated from Abies holophylla had the most potent disease control activity; it showed control values of more than 90% against five plant diseases, except for tomato late blight. On the other hand, fourteen(7.5%) solid culture extracts exhibited potent disease control values of more than 90% against one of six plant diseases. The screening results of this study strongly suggested that metabolites of plant endophytic fungi could be good potential sources for screening programs of bioactive natural products.

• Journal of Microbiology
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• 제43권6호
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• pp.475-486
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• 2005

Fungal secondary metabolites constitute a wide variety of compounds which either playa vital role in agricultural, pharmaceutical and industrial contexts, or have devastating effects on agriculture, animal and human affairs by virtue of their toxigenicity. Owing to their beneficial and deleterious characteristics, these complex compounds and the genes responsible for their synthesis have been the subjects of extensive investigation by microbiologists and pharmacologists. A majority of the fungal secondary metabolic genes are classified as type I polyketide synthases (PKS) which are often clustered with other secondary metabolism related genes. In this review we discuss on the significance of our recent discovery of chalcone synthase (CHS) genes belonging to the type III PKS superfamily in an industrially important fungus, Aspergillus oryzae. CHS genes are known to playa vital role in the biosynthesis of flavonoids in plants. A comparative genome analyses revealed the unique character of A. oryzae with four CHS-like genes (csyA, csyB, csyC and csyD) amongst other Aspergilli (Aspergillus nidulans and Aspergillus fumigatus) which contained none of the CHS-like genes. Some other fungi such as Neurospora crassa, Fusarium graminearum, Magnaporthe grisea, Podospora anserina and Phanerochaete chrysosporium also contained putative type III PKSs, with a phylogenic distinction from bacteria and plants. The enzymatically active nature of these newly discovered homologues is expected owing to the conservation in the catalytic residues across the different species of plants and fungi, and also by the fact that a majority of these genes (csyA, csyB and csyD) were expressed in A. oryzae. While this finding brings filamentous fungi closer to plants and bacteria which until recently were the only ones considered to possess the type III PKSs, the presence of putative genes encoding other principal enzymes involved in the phenylpropanoid and flavonoid biosynthesis (viz., phenylalanine ammonia-lyase, cinnamic acid hydroxylase and p-coumarate CoA ligase) in the A. oryzae genome undoubtedly prove the extent of its metabolic diversity. Since many of these genes have not been identified earlier, knowledge on their corresponding products or activities remain undeciphered. In future, it is anticipated that these enzymes may be reasonable targets for metabolic engineering in fungi to produce agriculturally and nutritionally important metabolites.

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2000년도 추계학술발표대회
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• pp.39-45
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• 2000

It hab been proposed that CHS3-mediated chitin synthesis during the vegitative cell cycle is regulated by CHS4. To investigate direct protein-protein interaction between their coding products, we used yeast two hybrid system and found that a domain of Chs3p was responsible for interaction with Chs4p. This domain, termed MIRC3-4 (maximum interacting region of chs3p with chs4p), spans from 647 to 700 residues. It is well conserved among CHS3 homologs of various fungi such as Candida albicans, Emericella nidulans, Neurospora crassa, Magnaporthe grisea, Ustilago maydis, Glomus versiforme, Exophiala dermatitidis, Rhizopus microsporus. A series of mutaion in the MIRC3-4 resulted in no appearance of chitin ring at the early G 1 phase but did not affect chitin synthesis in the cell wall after cytokinesis. Absence of chitin ring could be caused either by delocalization of Chs3p to the septum or by improper interaction with Chs4p. To discriminate those two, not mutually exclusive, alternatives, mutants cells were immunostained with Chs3p-specific antibody. Some exhibited localization of chs3p to the septum, while others failed. These results indicate that simultaneous localization and activation Chs3p by Chs4p is required for chitin ring synthesis.

• The Plant Pathology Journal
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• 제15권5호
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• pp.280-286
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• 1999

Lichen-forming (LFF) or lichenicolous fungi (LCF) were isolated from the lichens collected at‘Backwoon’mountain area,‘Chiri’mountain area and‘Sorok’island in the southern regions of Korea and were screened for antagonistic efficacy against several phyto-pathogenic fungi. Symbiotic algae-free LFF and LCF were isolated by the following methods: I) discharged spores (ascospores), II) macerated thallus suspension and III) direct use of thallus fragments. Among 58 isolates obtained from 34 lichens, 8 isolates showed antifungal activity against Rhizoctonia solani. Antifungal activities of the strongest antagonistic isolate (LB9810) originated from the thallus of Parmelia quercina lichen were evaluated against 15 phyto-pathogenic fungi. When crude methanol extract of mycelia of the LB8910 isolate was employed at the rate of 0.5% (v/w), fungal growth of Magnaporthe grisea and Rhizoctonia solani was severly and Rhizoctonia solani was severly inhibited as much as approximately 60% compared to control. Growth of various food-borne same extract. The extract was successively partitioned with n-hexane, ethyl acetate and n-butanol. n-Hexane fraction displayed the strongest antifungal activities against R. solani. The LB9810 isolate was finally identified as Fusarium equiseti (Corda) Sacc., which has not been reported as LFF or LCF yet. Therefore, it is very likely that F. equiseti isolated it the study was originated from the contaminants associated with thallus fragments rather than from LFF or LCF.

• 농약과학회지
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• 제5권3호
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• pp.26-35
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• 2001

식물자원으로부터 식물병원균에 대한 항균물질을 탐색하고자 국내에서 재배한 40종의 약용식물 추출물을 대상으로 항균활성을 검색하였다. 우선, 각 식물을 methanol (MeOH)로 추출, 농축한 MeOH추출물을 시료로 하여 $2000{\mu}g/mL$ 농도수준에서 6가지 식물병에 대한 in vivo 방제효과를 조사하였다. 40종의 시료 중 14종의 시료가 적어도 한가지이상의 식물병에 대하여 90% 이상의 방제효과를 나타내었다. 벼 도열병, 토마토 역병 및 밀 붉은녹병에 대해서는 각각 8개, 7개 및 3개의 시료가 90% 이상의 효과를 나타내었으나, 벼 잎집무늬마름병, 토마토 잿빛곰팡이병 및 보리 흰가루병에 대해서는 90% 이상의 방제효과를 보이는 시료는 없었다. 벼 도열병에 대하여 높은 활성을 보이는 당귀(Angelica gigas, 당귀(當歸))와 백지 (Angelica dahurica, 백지(白芷))의 MeOH추출물로부터 solvent partitioning과 column chromatography를 통하여 각각 1개 및 2개의 항균물질을 분리하였으며 이들 물질은 질량분석 및 핵자기공명분석에 의하여 모두 coumarin계 물질인 decursin, imperatorin 및 isoimperatorin으로 동정되었다. 구조와 항균활성간의 관계를 알아보기 위하여 분리한 3개의 물질을 7번 위치에 free hydroxyl기를 가지고 있는 umbelliferone (7-hydroxycoumarin)과 scopoletin (6-methoxy-7-hydroxycoumarin)과 비교하여 in vitro 및 in vivo 항균활성을 조사하였다. In vitro에서 균사생육억제활성을 조사한 결과, 이들 물질들은 대상식물병원 곰팡이에 대하여 50% 균사생육억제농도 ($IC_{50}$)가 대부분 $200{\mu}g/mL$ 이상으로 나타나 항균활성이 비교적 약한 것으로 나타났다. 또한 7번 위치에 hydroxyl기가 노출되어 있는 umbelliferone과 scopoletin보다는 7번 위치의 free hydroxyl기 대신에 cyclic alkoxy기로 존재하는 decursin과 imperatorin이 곰팡이에 대한 항균활성이 강한 것으로 나타났다. 특히, decursin과 imperatorin은 각각 Pythium ultimum과 Magnaporthe grisea에 대하여 $25{\mu}g/mL$ 이하의 $IC_{50}$를 보여 강한 항균활성을 나타냈다. In vivo 실험에서는 decursin과 imperatorin은 여섯 가지 식물병 중 벼 도열병에 대하여 항균활성이 높은 것으로 나타났으며, 다른 세 개의 물질은 식물병 방제활성이 거의 없는 것으로 나타났다. 이상의 실험결과 7-hydroxycoumarin계 물질들의 항진균활성과 관련하여 7번 위치에 free hydroxyl기가 있는 것보다는 이 hydroxyl기가 보다 안정한 cyclic alkoxy기로 치환되는 것이 높은 항균활성을 나타내는데 중요하다는 것을 알 수 있었다.

• 한국균학회지
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• 제32권1호
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• pp.31-38
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• 2004

오이 뿌리조직으로부터 분리한 식물내생세균 EB215균은 탄저병균인 Colletotrichum species에 대하여 강한 항균활성을 보였다. 이 균은 생리 생화학적 특성과 Biolog 실험 및 16S rDNA 유전자 서열에 의해 Burkholderia cepacia로 동정되었다. 이 균의 항균물질 생산을 위한 최적배지는 nutrient 액체(NB) 배지로 그리고 배양기간은 3일로 결정되었다. B. cepacia EB215 균주의 NB 배양체로부터 원심분리, n-hexane 분획, silica gel 컬럼, preparative TLC 및 in vitro 생물검정 등을 통하여 한 개의 항균물질을 분리하였다. 이 물질은 질량분석과 핵자기공명 분석을 통하여 pyrrolnitrin으로 동정되었다. Pyrrolnitrin은 고추 탄저병(Colletotrichum coccodes), 오이 탄저병(Colletotrichum orbiculare), 벼 도열병(Magnaporthe grisea), 벼 잎집무늬마름병(Corticium sasaki) 등의 4가지 식물병에는 $11.1\;{\mu}g/ml$ 낮은 농도에서도 90% 이상의 높은 방제활성을 보였다. 그리고 또한 토마토 잿빛곰팡이병(Botrytis cinerea)과 밀 붉은녹병(Puccinia recondita)에 대해서는 $33.3\;{\mu}g/ml$ 이상의 농도에서 90% 이상의 방제활성 보였다. 하지만 Phytophthora infestans에 의한 토마토 역병에 대해서는 전혀 항균활성이 없었다. 앞으로 B. cepacia EB215균을 이용한 미생물살균제 개발에 대하 연구를 진행할 예정이다.