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

• 농약과학회지
• /
• 제8권4호
• /
• pp.338-346
• /
• 2004

홀아비꽃대(Chloranthus japonicus) 뿌리 조직의 메탄을 추출물은 벼 도열병(Magnaporthe grisea), 벼 잎집무늬마름병(Corticium sasaki), 토마토 잿빛곰팡이병(Botrytis cinerea), 토마토 역병(Phytophthora infestans) 및 밀 붉은녹병(Puccinia recondita) 등의 다양한 식물병을 효과적으로 방제하였다. 이 메탄올 추출물로부터 3개의 항균물질을 분리하였고 이들은 질량분석과 핵자기공명분석을 통하여 shizukanol B, C 및 D로 동정되었다. 이들 세 개의 물질들 중에서 shizukanol C가 실험한 식물병원균들의 균사생육 저해 활성이 가장 큰 것으로 나타났다. 즉, $12.5{\mu}g/m\ell$ 이상의 농도에서 벼 도열병균과 고추 탄저병균(Colletotrichum gloeosporioides와 C. acutatum)의 균사 생육을 완전히 억제하였고, $3.13{\mu}g/m\ell$ 이상의 농도에서는 토마토 역병균의 균사 생육이 완전히 억제되었다. 세 가지 물질은 또한 in vivo에서 벼 도열병과 밀 붉은녹병에 대하여 특히 높은 방제효과를 보였다. 다른 한편으로 세 가지 물질들은 밀과 보리 잎에 약해를 유발하였고, 또한 좀개구리밥(Lemna paucicosta)의 생장을 억제하였으며, shizukanol B, C, D의 50% 생육억제 농도는 각각 $30.0{\mu}g/m\ell$, $49.9{\mu}g/m\ell$ 및 $154{\mu}g/m\ell$였다. 그리고 shizukanol C는 시험한 5종류의 해충중에서 벼멸구(Nilaparavata lugens), 복숭아혹진딧물(Myzus persicae), 배추좀나방(Plutella xylostella) 및 담배거세미나방(Spodoptera litura)에 대해서 $1,000{\mu}g/m\ell$ 수준에서 60% 이상의 살충활성을 보였다.

• The Plant Pathology Journal
• /
• 제26권4호
• /
• pp.386-393
• /
• 2010

In order to study disease resistance mechanisms in rice against the rice blast fungus Magnaporthe grisea, we screened fungal elicitor-responsive genes from rice suspension-cultured cells treated with fungal elicitors employing differential hybridization (DH). By DH screening, 31 distinct rice clones were isolated and a majority of them were full-length cDNAs encoding pathogenesisrelated (PR) genes. Sixteen of the 31 genes were upregulated at 4, 8, and 12 h following fungal elicitor treatment. To elucidate the effect of signal molecules and biotic elicitors on the regulation of rice defense genes, we further characterized the transcriptional expression patterns of representative isolated PR genes; OsGlu1, OsGlu2, OsTLP, OsRLK, and OsPR-10, following treatment with fungal elicitor, phytohormones, cycloheximide, and inhibitors of protein phosphorylation. Jasmonic acid (JA) induced transcriptional expression of OsGlu1, OsTLP, and OsRLK, but not of OsGlu2 and OsPR-10 at any of the tested time points. Salicylic acid (SA) and abscisic acid weakly induced the expression of OsTLP and OsRLK. SA showed an antagonistic effect with fungal elicitor and JA. Cycloheximide suppressed all these genes upon elicitor treatment, except for OsGlu2. Staurosporine only induced the expression of OsRLK. Application of calyculin A strongly induced OsRLK expression, but suppressed the expression of OsGlu2. Our study yielded a number of PR genes that play a role in defense mechanisms against the rice blast fungus, as well as contribute towards the elucidation of crosstalk between phytohormones and other modifications during defense signaling.

• Molecules and Cells
• /
• 제27권5호
• /
• pp.563-570
• /
• 2009

We previously isolated the OsCBT gene, which encodes a calmodulin (CaM)-binding protein, from a rice expression library constructed from fungal elicitor-treated rice suspension cells. In order to understand the function of OsCBT in rice, we isolated and characterized a T-DNA insertion mutant allele named oscbt-1. The oscbt-1 mutant exhibits reduced levels of OsCBT transcripts and no significant morphological changes compared to wild-type plant although the growth of the mutant is stunted. However, oscbt-1 mutants showed significant resistance to two major rice pathogens. The growth of the rice blast fungus Magnaporthe grisea, as well as the bacterial pathogen Xanthomonas oryzae pv. oryzae was significantly suppressed in oscbt-1 plants. Histochemical analysis indicated that the hypersensitive-response was induced in the oscbt-1 mutant in response to compatible strains of fungal pathogens. OsCBT expression was induced upon challenge with fungal elicitor. We also observed significant increase in the level of pathogenesis-related genes in the oscbt-1 mutant even under pathogen-free condition. Taken together, the results support an idea that OsCBT might act as a negative regulator on plant defense.

• 한국육종학회지
• /
• 제40권4호
• /
• pp.408-413
• /
• 2008

벼 조생종 품종 금오3호의 잎도열병 저항성 및 도열병 저항성 연관마커 zt56591과의 관계를 분석한 결과, '03~'07년까지 5년간 전국 14개 지역 잎도열병 밭못자리 검정의 평균 발병정도는 금오3호가 1.6으로 진부벼 3.6, 금오벼 5.3 및 일품벼 6.4에 비해 낮았다. 저항성(0-3) 12개소, 중도 저항성(4-6) 2개소이며, 감수성(7-9)을 보인 곳은 없었다. 도열병 내구저항성에서 병반 면적율이 0.1~5.0%사이로 지속적인 저항성을 보였으며, 29개 균주에 저항성반응을 보였고, 1개 균주에 대해서는 이병성 반응을 보였다. 도열병 저항성과 연관된 DNA marker를 이용하여 분석한 결과 '금오3호'는 도열병 광범위 저항성 유전자로 알려진 Pizt와 연관된 마커 zt56591에 저항성 밴드 패턴을 나타내었다. 또한, 아끼다고마찌/금오3호 RIL집단에서 Pizt 연관마커와 잎도열병 저항성과의 관계를 분석한 결과 조환가가 1.1%로 밀접히 연관되어 있어 '금오3호'와 교배된 후대집단에서 zt56591마커를 이용한 MAS선발도 가능할 것으로 판단되었다.

• Molecules and Cells
• /
• 제23권1호
• /
• pp.108-114
• /
• 2007

The mitogen-activated protein kinase (MAPK) signaling cascade is critical for regulating plant defense systems against various kinds of pathogen and environmental stresses. One component of this cascade, the MAP kinase kinases (MAPKK), has not yet been shown to be induced in plants following biotic attacks, such as those by insects and fungi. We describe here a gene coding for a blast (Magnaporthe grisea)- and insect (Nilaparvata lugens)-responsive putative MAPK kinase, OmMKK1 (Oryza minuta MAPKK 1), which was identified in a library of O. minuta expressed sequence tags (ESTs). Two copies of OmMKK1 are present in the O. minuta genome. They encode a predicted protein with molecular mass 39 kDa and pI of 6.2. Transcript patterns following imbibition of plant hormones such as methyl jasmonic acid (MeJA), ethephone, salicylic acid (SA) and abscisic acid (ABA), as well as exposure to methyl viologen (MV), revealed that the expression of OmMKK1 is related to defense response signaling pathways. A comparative analysis of OmMKK1 and its O. sativa ortholog OsMKK1 showed that both were induced by stress-related hormones and biotic stresses, but that the kinetics of their responses differed despite their high amino acid sequence identity (96%).

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

• 한국육종학회지
• /
• 제51권4호
• /
• pp.395-403
• /
• 2019

우리나라의 도열병 균계에 내구저항성을 보이는 자포니카 벼 품종 팔공의 저항성 유전좌위를 분석한 결과, 팔공 allele에 의한 저항성 관련 putative QTLs가 2번, 4번, 7번, 11번 염색체상에서 9개 좌위들이 확인되었다. 팔공의 allele에 의한 도열병 저항성 연관 유전자좌들 중 qBn2.3 (Ch r. 2), qBn4.2 (Ch r. 4), qBn11.1 및 qBn11.2 (Ch r. 11) 등 4개 좌위는 표현형 변이의 28-56.7%를 설명하는 major QTL이었고, 이들 좌위에서는 1-4개의 저항성 관련 유전자들이 위치하는 것으로 보고되었다. 팔공 allele의 5개 QTLs qBn2.1, qBn2.4 (Ch r. 2), qBn4.1 (Chr. 4), qBn7.1 및 qBn7.2 (Ch r. 7) 등은 표현형 변이를 9.7-18.8% 설명하였으며, 이들 좌위들 중 2번 염색체상의 qBn2.1를 제외한 4개 QTLs 좌위에서는 다른 유전자의 보고가 없어 팔공 고유의 도열병 저항성 관련 유전 요소들로 추정 된다. 팔공의 도열병 내구 저항성은 2번, 4번, 7번, 11번 염색체상의 9개 QTLs들의 상호 작용에 의한 것으로 생각되며, 특히 목도열병 내구 저항성 유전자 Pb1이 위치하는 것으로 보고된 좌위의 qBn11.2는 표현형 변이 56.7%를 설명하였고 내구저항성에서 중요한 역할을 하는 것으로 생각된다. 팔공의 줄무늬잎마름병 저항성은 qBn11.2 좌위의 Stvb-i 유전자에 의한 것으로 생각된다.

• The Plant Pathology Journal
• /
• 제22권4호
• /
• pp.323-328
• /
• 2006

Serratia marcescens W1, isolated from cucumber-cultivated soil in Suwon, Korea, evidenced profound antifungal activity and produced the extracellular hydrolytic enzymes, chitinase and protease. In order to isolate the antifungal genes from S. marcescens W1, a cosmid genomic library was constructed and expressed in Escherichia coli. Transformants exhibiting chitinase and protease expression were selected, as well as those transformants evidencing antifungal effects against the rice blast fungus, Magnaporthe grisea, and the cucumber leaf spot fungus, Cercospora citrullina. Cosmid clones expressing chitinase or protease exerted no inhibitory effects against the growth of fungal pathogens. However, two cosmid clones evidencing profound antifungal activities were selected for further characterization. An 8.2 kb HindIII fragment from these clones conditioned the expression of antagonistic activity, and harbored seven predicted complete open reading frames(ORFs) and two incomplete ORFs. The deduced amino acid sequences indicated that six ORFs were highly homologous with genes from S. marcescens generating pyrroloquinoline quinone(PQQ). Only subclones harboring the full set of pqq genes were shown to solubilize insoluble phosphate and inhibit fungal pathogen growth. The results of this study indicate that the functional expression of the pqq genes of S. marcescens W1 in E. coli may be involved in antifungal activity, via as-yet unknown mechanisms.

• 식물병연구
• /
• 제14권1호
• /
• pp.21-25
• /
• 2008

본 연구는 잎도열병에 대한 합리적 약제방제수준을 설정하기 위하여 수행하였다. 발병은 온실에서 도열병균을 접종하여 발병시킨 전파식물을 시험식물 이앙 2주 후에 이식하여 발병을 유도하였다. 발병정도 설정은 병 발생 최성기에 병반면적율에 따라 수준을 설정하고 표식하였다. 병반면적율에 따라 주당이삭수, 이삭당입수, 등숙율, 천립중 그리고 수량에 대한 상관을 분석한 결과 주당이삭수, 등숙율, 수량과는 1%수준에서 -0.97, -1.00, -0.96의 부의 상관이 있었으며, 이삭당입수와 천립중은 1% 수준에서 공히 0.98의 정의 상관이 있었다. 수익역치(GT) 값은 방제비용을 쌀 시장가격으로 나누어 8.35가 되며, 경제적 피해수준(EIL)은 수익역치값을 회귀식의 피해계수로 나눈 값이 된다. 경제적 방제수준(ET)은 EIL값에다 80%를 곱한 값이 된다. 본 시험에서의 경제적 피해허용 수준은 주당 이삭수, 이삭당입수, 등숙율, 천립중, 수량에서 각각 병반면적율 41.77%, 9.74%, 19.01%, 291.06%, 3.36%가 된다. 수량에 대한 경제적 방제수준은 2.7%가 된다($3.4%(EIL){\times}0.8$). 수량에서의 경제적 방제수준은 하위 2엽이 거의 병반으로 덮여 있거나 20개 이상의 대형병반이 하위엽에 발생하였을 때 방제하는 시점으로 나타났다.