• 식물병과 농업
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• 제1권1호
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• pp.19-29
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• 1995

A microbial product composed of three antagonistic fungal isolates (Aspergillus sp., Penicillium sp. and Trichoderma sp.) and three bacterial isolates (Arthrobacter sp., Bacillus sp., and Pseudomonas sp.) was tested for the control of Pythium blight caused by Pythium sp., brown patch by Rhizoctonia solani (anastomosis group(AG) 1-1) and large patch by R. solani (AG 2-2) of turfgrasses. Cultures of the antagonistic fungi and bacteria varied in the effectiveness in reducing disease severity of Pytium blight and brown patch on bentgrass. The antagonistic fungal and bacterial isolates were mixed and cultured at 20-$25^{\circ}C$ for 3 days in a growth medium, and the diluted solution of the microbial culture was applied under the field conditions after inoculation of the above turfgrass pathogens. The treated turfgrass was incubated at 28$^{\circ}C$ in a growth chamber. In this experiment, Pythium blight was almost completely controlled and brown patch was slightly decreased by the microbial product, while no control was observed in large patch of zoysiagrass. In zoysiagrass treated with the microbial culture, thatch accumulation was notably reduced.

• 한국식물병리학회지
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• 제12권2호
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• pp.237-244
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• 1996

길항곰팡이 3종(Aspergillus sp. A101, Penicillium sp. B202, Trichoderma sp. C303), 길항세균 3종(Arthrobacter sp. AN303)또는 이들 모두의 혼합균주를 배양하여 creeping bentgrass 양묘장에 처리하여 Pythium blight, brown patch 및 dollar spot의 방제효과를 조사하였다. 또한 길항미생물 6종의 배양액을 살균제와 병용하여 그린에 살포하여 이들 토양병에 대한 방제효과를 조사하였다. 양묘장에서는 미생물의 종류에 관계없이 Pythium blight 억제효과가 커 3회 이상 미생물제 처리시 병이 전혀 발생하지 않았다. 그러나 brown patch와 dollar spot은 미생물제에 의한 방제효과가 크지 않았으며, 살균제에 의해 효과적으로 방제되었다. 미생물제와 살균(Pythium blight 방제용 살균제 제외)를 병용하여 처리한 그린에서는 살균제 단독처리와 비교할 때 brown patch는 유의적으로 억제되었고 Pythium blight와 dollar spot은 차이가 없었다.

• The Plant Pathology Journal
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• 제25권3호
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• pp.263-269
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• 2009

Bacterial wilt, Fusarium wilt and Foot rot caused by Ralstonia solanacearum, Fusarium oxysporum, and Phytophthora capsici respectively, continue to be severe problems to tomato, potato and black pepper growers in Vietnam. Three bio-products, Bacillus vallismortis EXTN-1 (EXTN-1), Bacillus sp. and Paenibacillus sp. (ESSC) and Bacillus substilis (MFMF) were examined in greenhouse bioassay for the ability to reduce bacterial wilt, fusarium wilt and foot rot disease severity. While these bio-products significantly reduced disease severities, EXTN-1 was the most effective, providing a mean level of disease reduction 80.0 to 90.0% against bacterial wilt, fusarium wilt and foot rot diseases under greenhouse conditions. ESSC and MFMF also significantly reduced fusarium wilt, bacterial wilt and foot rot severity under greenhouse conditions. Bio-product, EXTN-1 with the greatest efficacy under greenhouse condition was tested for the ability to reduce bacterial wilt, fusarium wilt and foot rot under field condition at Song Phuong and Thuong Tin locations in Ha Tay province, Vietnam. Under field condition, EXTN-1 provided a mean level of disease reduction more than 45.0% against all three diseases compared to water treated control. Besides, EXTN-1 treatment increased the yield in tomato fruits 17.3% than water treated control plants.

• The Plant Pathology Journal
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• 제23권2호
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• pp.97-102
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• 2007

A total of 39 essential oils were tested for antifungal activities as volatile compounds against five phytopathogenic fungi at a dose of 1 ${\mu}l$ per plate. Five essential oils showed inhibitory activities against mycelial growth of at least one phytopathogenic fungus. Origanum vulgare essential oil inhibited mycelial growth of all of the five fungi tested. Both Cuminum cyminum and Eucalyptus citriodora oils displayed in vitro antifungal activities against four phytopathogenic fungi except for Colletotrichum gloeosporioides. The essential oil of Thymus vulgaris suppressed the mycelial growth of C. gloeosporioides, Fusarium oxysporum and Rhizoctonia solani and that of Cymbopogon citratus was active to only F. oxysporum. The chemical compositions of the five active essential oils were determined by gas chromatography-mass spectrometry. This study suggests that both E. citriodora and C. cyminum oils have a potential as antifungal preservatives for the control of storage diseases of various crops.

• The Plant Pathology Journal
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• 제21권3호
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• pp.244-251
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• 2005

The induction of growth promotion on numerous crops by rhizobacteria is a well documented phenomenon. In case of tomato (Lycopersicon esculentum), fruit yield is higher in replant soil than that in fresh soil. To investigate what kind of rhizobacterium is involved, microbial community in rhizosphere and on rhizoplane of tomato plants from each soil was analyzed by dilution plating on selective media. Many Gram-negative bacteria and actinomycetes were isolated from tomato in replant soil. One Gram-negative rhizobacterium isolated was identified as Pseudomonas putida based on its biochemical characteristics, fatty acid methyl ester analysis and 16S rDNA sequence. This bacterium designated strain 17 inhibited the growth of Pseudomonas corrugata, and increased growth of tomato seedlings. In addition, its culture filtrate inhibited conidial germination of plant-pathogenic fungi such as Fusarium oxysporum f. sp. radicis-lycopersici, F. oxysporum f. sp. cucumerinum, and Nectria radicicola. Scanning electron microscopy revealed strain 17 colonized and persisted on the epidermal surfaces of tomato radicles and roots. These results suggest that P. putida strain 17 may serve as a biological control agent to suppress multiple soil-borne diseases for tomato plants. Increased microbial populations that suppress deleterious microorganisms including pathogens could be one of the major factors in increased tomato yield in replant soil.

• Journal of Ginseng Research
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• 제40권1호
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• pp.28-37
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• 2016

Background: Panax ginseng cannot be cultivated on the same land consecutively for an extended period, and the underlying mechanism regarding microorganisms is still being explored. Methods: Polymerase chain reaction and denaturing gradient gel electrophoresis (PCR-DGGE) and BIO-LOG methods were used to evaluate the microbial genetic and functional diversity associated with the P. ginseng rhizosphere soil in various cultivation ages and modes. Results: The analysis of microbial diversity using PCR-DGGE showed that microbial communities were significantly variable in composition, of which six bacterial phyla and seven fungal classes were detected in P. ginseng soil. Among them, Proteobacteria and Hypocreales dominated. Fusarium oxysporum, a soilborne pathogen, was found in all P. ginseng soil samples except R0. The results from functional diversity suggested that the microbial metabolic diversity of fallow soil abandoned in 2003was the maximum and transplanted soil was higher than direct-seeding soil and the forest soil uncultivated P. ginseng, whereas the increase in cultivation ages in the same mode led to decreases in microbial diversity in P. ginseng soil. Carbohydrates, amino acids, and polymers were the main carbon sources utilized. Furthermore, the microbial diversity index and multivariate comparisons indicated that the augmentation of P. ginseng cultivation ages resulted in decreased bacterial diversity and increased fungal diversity, whereas microbial diversity was improved strikingly in transplanted soil and fallow soil abandoned for at least one decade. Conclusion: The key factors for discontinuous P. ginseng cultivation were the lack of balance in rhizosphere microbial communities and the outbreak of soilborne diseases caused by the accumulation of its root exudates.

• 식물병연구
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• 제15권1호
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• pp.30-35
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• 2009

청양지역을 비롯한 멜론 연작재배지에서 매년 피해를 나타내고 있는 시들음 증상 발생주의 뿌리로부터 뿌리씩 음병 원균 Monosporascus cannonballus(28.4%), Fusarium spp.(27.4%), Didymella bryoniae(24.2%), Phytophthora spp.(20.0%) 등을 각각 분리하였다. 멜론 연작재배 토양내 뿌리썩음병 방제를 위해 고온수 관주 및 훈증제 3종 살균처리하고 방제효율을 검정하였다. 고온수($92{\sim}98^{\circ}C$) 토양관주 살균처리는 $'05{\sim}'06$년 정식전 4시간(관주량: $52{\sim}55$ tons/10a) 관주하였다. 그 결과 발병율이 0.01$\sim$0.08%로 무처리의 발병량(6.6$\sim$81.4%)보다 높은 방제효과를 나타내었다(p<0.05). 이는 토양훈증 살균제 3종의 방제효과(54.8$\sim$79.7%) 보다 20.2$\sim$45.1% 높았다. 또한, 고온수 관주처리 토양에서의 역병(Fire blight), 시들음병 (Fusarium wilt)의 발병율도 극히 낮았다 한편, 2005-2006년 고온수 관주처리구의 수량은 39톤/ha으로 무처리구(13.6톤/ha)에 비해 매우 높아 고도의 유의성을 나타내었다(P<0.05). 그러나, Dazomet, methyl bromide등 훈증제 처리는 약제 처리간 유의성은 없었으나 수량은 무처리 보다 39$\sim$47% 높았다. 결과적으로 고온수($92{\sim}98^{\circ}C$)를 이용한 연작재배지 토양 살균은 토양병해에 높은 방제효과를 나타내어 약제에 의한 훈증살균보다 효과적이라 판단되었다.

• 식물병연구
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• 제20권1호
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• pp.21-24
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• 2014

Plasmodiophora brassicae는 십자화과 작물에 뿌리혹병을 일으키는 주요 병원균이다. 본 연구에서는 뿌리혹병균의 신속 정확한 검출을 위해서 뿌리혹병균에 대한 새로운 종 특이적 프라이머를 개발하고자 하였다. 새롭게 개발된 프라이머들은 10종의 주요 토양병원균을 비롯하여 기주인 배추 DNA와는 반응하지 않고 P. brassicae와만 반응하는 특이성을 갖고 있었다. 그 가운데 Primer ITS1-1/1-2는 민감도 검정 결과, 10 spores/ml의 DNA까지 검출이 가능함으로써, first round PCR용임에도 불구하고 이전의 검출법 보다 감도가 높고 정확한 결과를 얻었다. Quantitative real-time PCR로 분석할 경우에는 더 적은 수의 포자까지 안정적으로 검출해 낼 수 있어 새로운 P. brassicae 종 특이적 프라이머로서의 유용성을 확인할 수 있었다.

• Journal of Microbiology and Biotechnology
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• 제16권3호
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• pp.450-456
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• 2006

Pseudomonas fluorescens MC07 is a growth-promoting rhizobacterium that suppresses mycelial growth in fungi such as Rhizoctonia solani, Pythium ultimum, Fusarium oxysporum, and Phytophthora capsici. To determine the role of the bacterium's antifungal activity in disease suppression, we screened 2,500 colonies generated by Tn5lacZ insertions, and isolated a mutant 157 that had lost antifungal activity. The EcoRI fragment carrying Tn5lacZ was cloned into pBluescript II SK(+) and used as a probe to isolate wild-type clones from a genomic library of the parent strain, MC07. Two overlapping cosmid clones, pEH4 and pEH5, that had hybridized with the mutant clone were isolated. pEH4 conferred antifungal activity to the heterologous host P.fluorescens strain 1855.344, whereas pEH5 did not. Through transposon mutagenesis of pEH4 and complementation analyses, we delineated the 14.7-kb DNA region that is responsible for the biosynthesis of an antifungal compound. DNA sequence analysis of the region identified 11 possible open reading frames (ORF), ORF1 through ORF11. A BLAST search of each putative protein implied that the proteins may be involved in an antifungal activity similar to polyketides.

• The Plant Pathology Journal
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• 제34권3호
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• pp.163-170
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• 2018

Strawberry Fusarium wilt disease, caused by Fusarium oxysporum f. sp. fragariae, is the most devastating disease in strawberry production. The pathogen produces chlamydospores which tolerate against harsh environment, fungicide and survive for decades in soil. Development of detection and quantification techniques are regarded significantly in many soilborne pathogens to prevent damage from diseases. In this study, we improved specific-quantitative primers for F. oxysporum f. sp. fragariae to reveal correlation between the pathogen density and the disease severity. Standard curve $r^2$ value of the specific-quantitative primers for qRT-PCR and meting curve were over 0.99 and $80.5^{\circ}C$, respectively. Over pathogen $10^5cfu/g$ of soil was required to cause the disease in both lab and field conditions. With the minimum density to develop the wilt disease, the pathogen affected near 60% in nursery plantation. A biological control microbe agent and soil solarization reduced the pathogen population 2-fold and 1.5-fold in soil, respectively. The developed F. oxysporum f. sp. fragariae specific qRT-PCR protocol may contribute to evaluating soil healthiness and appropriate decision making to control the disease.