• 한국균학회지
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• 제24권3호통권78호
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• pp.167-175
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• 1996

Ganoderma lucidum 균주는 인공 배지 상에서 광에 의하여 자실체 원기가 형성되었으며, 광질이 자실체 원기 형성에 미치는 영향을 조사한 결과, 자실체 원기 형성능을 가지고 있는 5균주중 3균주는 공시한 모든 형광등의 아래에서 즉, BLB, 순청색, 순녹색, 순황색, 순적색 형광등의 아래에서 자실체 원기가 형성되었고, 2균주는 BLB 형광등을 제외한 가시광선 영역에서 형성되었다. 그러나 암상태에서는 공시한 모든 균주가 자실체를 형성하지 않았다. 자실체 원기는 광도 0.05에서 $10.0\;{\mu}mol\;m^{-2}s^{-1}$의 범위에서 형성되었고, 광도가 $0.5\;{\mu}mol\;m^{-2}s^{-1}$ 이상에서는 자실체 원기의 수가 감소하였다. 주기적인 광조사가 자실체 원기의 형성에 미치는 영향을 조사한 결과, Gl-009균주는 자실체 원기의 수와 무게가 연속광을 조사한 경우보다 증가하였다. 자실체원기를 형성하기 위해서는 최소 4일간의 광조사가 필요하였다. 단색광의 조사가 자실체 원기의 형성에 미치는 영향을 조사한 결과 Gl-003 균주는 400에서 800 nm의 모든 단색광 처리구에서 자실체 원기가 형성되었고, 그 외의 4균주는 400에서 500 nm, 그리고 700에서 750 nm 범위에서 형성되었다.

• 농약과학회지
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• 제19권2호
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• pp.125-133
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• 2015

해충방제에 있어서 곤충병원성 곰팡이는 화학농약을 대체할 수 있는 생물학적 방제인자로써 개발하기 위한 연구가 진행되고 있다. 나비목의 파밤나방과 배추좀나방 유충은 다양한 작물에 피해를 주는 주요 해충이지만 다양한 살충제에 대한 높은 저항성으로 인해 효과적인 방제가 이루어지지 않고 있다. 안동에 위치한 파재배지에서 채집한 파밤나방 유충에서 곰팡이 균주를 분리하였고, 이 균주의 형태적 특성과 분자생물학적 특성에 관하여 동정하였다. 그 결과, 기존의 Beauveria bassiana와 동일함을 확인하였고, B. bassiana ANU1으로 명명하였다. B. bassiana ANU1의 병원성 조사는 파밤나방과 배추좀나방 2령 유충을 대상으로 수행하였다. 파밤나방과 배추좀나방에 대한 반수치사농도는 각각 $2.7{\times}10^3$과 $0.9{\times}10^3conidia/ml$이었으며, 반수치사시간은 각각 65.6과 60.8시간으로 조사되었다. 또한 B. bassiana ANU1는 상대습도 50% 조건에서 일정온도 ($20^{\circ}C-30^{\circ}C$)와 $25^{\circ}C$의 온도에서 40%-70%의 습도조건에 노출되었을 때 $10^7conidia/ml$의 농도에서 파밤나방과 배추좀나방 유충을 대상으로 높은 병원성을 나타내었다.

• 한국균학회지
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• 제44권1호
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• pp.36-47
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• 2016

본 연구는 식물 근권에서 분리한 유용미생물 PA1, PA2, PA4, PA5, PA12 의 식물 생장 촉진능력과 식물 병원성 진균인 Colletotrichum acutatum, C. coccodes, C. gloeosporioides, C. dematium, Botrytis cinerea, Rhizoctonia solani, Sclerotinia minor 그리고 Fusarium sp.에 대한 생장억제능력을 평가하는데 그 목적이 있다. In vitro 실험에서 유용미생물의 식물 병원성 진균의 생장억제 능력을 확인하기 위해 세균배지인 TSA 배지와 곰팡이 배지인 PDA배지, 그리고 TSA와 PDA배지를 각각 50%씩 혼합한 배지(v/v, 1:1)에서 대치배양을 실시하였다. 그 결과 PDA배지에서는 PA2가 C. coccodes에 대해 65.5%로 가장 높은 억제능력을 보였으며, TSA배지에서는 PA2가 S. minor에 대해 96.5%로 가장 높은 억제력을 보였다. 또한 PDA와 TSA를 혼합한 배지에서는 PA2가 C. acutatum에 대해 58.5%로 가장 높은 억제능력을 보였다. 분리한 5균주 모두에서 식물병원성 진균에 대하여 생물적 방제 효과가 있음을 확인하였다. 또한 식물생장 촉진능력을 유발하는 원인물질을 탐색하기 위해 siderophore, protease, chitinase, hydrogen cyanide (HCN) 생성 유무를 확인하였고, phosphate solubilizing 실험을 실시하였다. 본 연구에서 사용된 유용미생물 5균주를 16s rDNA sequencing 결과 PA1, PA2는 Bacillus subtilis, PA4, PA5, PA12 각각 Bacillus altitudinis, Paenibacillus polymyxa, Bacillus amyloliquefaciens로 동정되었다.

• 한국작물학회지
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• 제45권2호
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• pp.143-149
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• 2000

From the soils of soybean fields in Cotton Branch Station (CBS) and Pine Tree Station (PTS), Arkansas, USA, various single spore isloates of sudden death syndrome (SDS) pathogen were obtained on modified Nash ＆ Snyder's medium (MNSM) with dilution plating technique and transferred to potato dextrose agar (PDA) medium to identify the cultural colony shape. The colony shapes of these isolates resembled F. solani isolate 171 which was white and chalky shaped on MNSM and most of them had unique form of morphology which produced white margin and blue center colony on PDA. Although, some of these isolates had more dark blue or showed slightly different color, all isolates that were selected randomly for green-house inoculation assay produced typical foliar symptoms on leaves of soybean, Hartz 6686. To determine the genetic differences among the isolates, mitochondrial DNA restriction fragment length polymorphism (RFLP) was conducted with fourty isolates from both fields, using mtDNA probes, 2U18 and 4U40, derived from Colletotrichum orbiculare. We obtained distinctive RFLPs in each treatment of restriction enzyme, EcoRI and HaeⅢ. Isolates, 11-2-5 and 14-3-1-1, from CBS and isolates, 104-3-1-2 and 701-1-5-1, from PTS showed different band patterns from 171 in both or in either treatment of restriction enzymes. Even if some of these isolates showed heterogeneous, they were more closer to 171 than PN603. And, also, rest of the thirty-six isolates had exactly same polymorphisms as 171 in each treatment of restriction enzyme. Although, some of the isolates showed the different morphological shape on PDA and slightly different band patterns on RFLPs, all of the isolates selected on MNSM due to their distinctive colony shape from other fungi produced the typical foliar symptoms on soybean leaves in greenhouse inoculation assay. It might be suggested that these isolates were not genetically different from check isolate 171 and they were unique strain of F. solani.

• Mycobiology
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• 제42권4호
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• pp.346-352
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• 2014

Recently, the Q biotype of tobacco whitefly has been recognized as the most hazardous strain of Bemisia tabaci worldwide, because of its increased resistance to some insecticide groups. As an alternative control agent, we selected an Isaria javanica isolate as a candidate for the development of a mycopesticide against the Q biotype of sweet potato whitefly. To select optimal mass production media for solid-state fermentation, we compared the production yield and virulence of conidia between 2 substrates (barley and brown rice), and we also compared the effects of various additives on conidia production and virulence. Barley was a better substrate for conidia production, producing $3.43{\times}10^{10}$ conidia/g, compared with $3.05{\times}10^{10}$ conidia/g for brown rice. The addition of 2% $CaCO_3+2%$ $CaSO_4$ to barley significantly increased conidia production. Addition of yeast extract, casein, or gluten also improved conidia production on barley. Gluten addition (3% and 1.32%) to brown rice improved conidia production by 14 and 6 times, respectively, relative to brown rice without additives. Conidia cultivated on barley produced a mortality rate of 62% in the sweet potato whitefly after 4-day treatment, compared with 53% for conidia cultivated on brown rice. The amendment of solid substrate cultivation with additives changed the virulence of the conidia produced; the median lethal time ($LT_{50}$) was shorter for conidia produced on barley and brown rice with added yeast extract (1.32% and 3%, respectively), $KNO_3$ (0.6% and 1%), or gluten (1.32% and 3%) compared with conidia produced on substrates without additives.

• Mycobiology
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• 제48권2호
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• pp.139-147
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• 2020

Root-feeding Scarabaeidae, particularly white grubs are considered among the most harmful coleopteran insect pests in turfgrass. In this work, sixteen entomopathogenic fungal species were assayed against flower chafer beetle, Protaetia brevitarsis (Coleoptera: Scarabaeidae) and Metarhizium anisopliae JEF-314 showed high virulence. The control ability of the isolate JEF-314 has been in detail tested for a model insect flower chafer beetle. Further analyses showed insect stage-dependent virulence where the fungal virulence was the highest against smaller instar larvae. Additionally, we confirmed that millet-based solid cultured granule was effective against the soil-dwelling larval stage. The isolate also showed a similar ability for a representative pest (Popillia spp.) in laboratory conditions. Our results clearly suggest a high potential of M. anisopliae JEF-314 to control the flower chafer beetle, possibly resulting in controlling of root-feeding white grubs in turfgrass. Based on the insect life cycle and susceptibility to the fungus, late spring and summer time would be the optimum time to apply JEF-314 granules for an effective control. Further characterization of the efficacy of the fungus under field conditions against the Scarabaeidae beetles might provide an efficient tool to control this beetle in an environment-friendly way.

• Mycobiology
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• 제48권4호
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• pp.326-329
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• 2020

Valuable natural compounds produced by a variety of microorganisms can be used as lead molecules for development of new agrochemicals. Furthermore, high-throughput in vitro screening systems with specific modes of action can increase the probability of discovery of new fungicides. In the current study, a rapid assay tested with various microbes was developed to determine the degree of respiratory inhibition of Saccharomyces cerevisiae in two different liquid media, YG (containing a fermentable carbon source) and NFYG (containing a non-fermentable carbon source). Based on this system, we screened 100 fungal isolates that were classified into basidiomycetes, to find microbial secondary metabolites that act as respiratory inhibitors. Consequently, of the 100 fungal species tested, the culture broth of an IUM04881 isolate inhibited growth of S. cerevisiae in NFYG medium, but not in YG medium. The result is comparable to that from treatment with kresoxim-methyl used as a control, suggesting that the culture broth of IUM04881 isolate might contain active compounds showing the inhibition activity for respiratory chain. Based on the assay developed in this study and spectroscopic analysis, we isolated and identified an antifungal compound (-)-oudemansin A from culture broth of IUM04881 that is identified as Oudemansiella venosolamellata. This is the first report that (-)-oudemansin A is identified from O. venosolamellata in Korea. Taken together, the development of this assay will accelerate efforts to find and identify natural respiratory inhibitors from various microbes.

• The Plant Pathology Journal
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• 제39권5호
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• pp.430-448
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• 2023

Recently, strategies for controlling Fusarium oxysporum f. sp. lycopersici (Fol), the causal agent of Fusarium wilt of tomato, focus on using effective biocontrol agents. In this study, an analysis of the biocontrol and plant growth promoting (PGP) attributes of 11 isolates of loamy soil Bacillus spp. has been conducted. Among them, the isolates B.PNR1 and B.PNR2 inhibited the mycelial growth of Fol by inducing abnormal fungal cell wall structures and cell wall collapse. Moreover, broad-spectrum activity against four other plant pathogenic fungi, F. oxysporum f. sp. cubense race 1 (Foc), Sclerotium rolfsii, Colletotrichum musae, and C. gloeosporioides were noted for these isolates. These two Bacillus isolates produced indole acetic acid, phosphate solubilization enzymes, and amylolytic and cellulolytic enzymes. In the pot experiment, the culture filtrate from B.PNR1 showed greater inhibition of the fungal pathogens and significantly promoted the growth of tomato plants more than those of the other treatments. Isolate B.PNR1, the best biocontrol and PGP, was identified as Bacillus stercoris by its 16S rRNA gene sequence and whole genome sequencing analysis (WGS). The WGS, through genome mining, confirmed that the B.PNR1 genome contained genes/gene cluster of a nonribosomal peptide synthetase/polyketide synthase, such as fengycin, surfactin, bacillaene, subtilosin A, bacilysin, and bacillibactin, which are involved in antagonistic and PGP activities. Therefore, our finding demonstrates the effectiveness of B. stercoris strain B.PNR1 as an antagonist and for plant growth promotion, highlighting the use of this microorganism as a biocontrol agent against the Fusarium wilt pathogen and PGP abilities in tomatoes.

• 한국약용작물학회지
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• 제27권6호
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• pp.404-411
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• 2019

Background: In September 2017, wilting and rhizome rot symptoms were observed on Atractylodes macrocephala Koidz. in Jecheon-si and Eumseong-gun. This study was carried out to isolate hitherto unidentified pathogenic fungi from A. macrocephala and to test the pathogenicity of isolated fungi against Atractylodes spp. genus such as A. macrocephala, A. japonica, and their interspecific hybrids. Methods and Results: The diseased plants were washed with running tap water, and the boundary between the healthy area and the diseased area was cut while the pathogens were isolated by growing cultures from the diseased areas on Phytophthora semi-selective medium. The internal transcribed spacer (ITS) region of the isolates was used in this study for identification. Test plants were cultivated in the glasshouse at 20℃ - 30℃ for 4 months and then used for pathogenicity test. The pots with plants inoculated with mycelial plugs and zoospores were placed at 25℃ for 48 h in a dew chamber where relative humidity was above 95%, and then moved into the glasshouse at 20℃ - 30℃. The presence or absence of pathogenicity of the strains was determined by evaluating the symptom of plant wilting. The inoculation test was performed in three replicates with a non-treated control. Conclusions: On the basis of results of ITS sequence analysis, the strains isolated from the diseased plants was identified as Phytophthora sansomeana. Biological assay using test plants confirmed the pathogenicity of P. sansomeana against Atractylodes macrocephala. This is the first report of rhizome rot in A. macrocephala caused by P. sansomeana.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 2003년도 정기총회 및 추계학술발표회
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• pp.84.2-85
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• 2003

Magnaporthee grisea causes the devastating blast disease of rice. Entensive research has been conducted on infection mechanisms, particularly on appressorium formation and penetration, of this fungus during the last decade. However, the role(s) of cell-wall-degrading enzymes (CWDEs) on pathogenesis is not clearly demonstrated at molecular level. Many CWDES in plant pathogenic fungi including M. grisea are redundant; that is, there are multiple genes encoding enzymes with a similar or overlapping spectrum of activities. It is laborious to isolate all of the genes encoding related enzymes and to construct mutants lacking all 9f them. Thus, we considered alternative strategies to address the role of CWDEs in pathogenesis. Since expression of CWDE genes Is repressed by a simple sugar, as the first step, we cloned a Snfl (sucrose non-fermenting) gene (MgSnf1) from M. grisea. The predicted amino acid sequence showed a high identity with other Snf1 genes from various fungi. To elucidate molecular function of MgSnf1, a transformant lacking MgSnf1 was created by targeted gene replacement. En glucose, sucrose, and xylan the MgSnf1 mutant grew normally but in pectin and complex media, it grew slower than wild type. Expression of various CWDEs in MgSnf1 mutant was investigated and found that expression of some CWDEs is repressed. However, no significant difference was observed in conidial germination, appressorium formation, and pathogenicity in MgSnf1 mutant. However, MgSnf1 functionally complemented a yeast MgSnf1 mutant. These results suggest that MgSnf1 is involved in regulation of CWDEs and MgSnf1 is dispensable in pathogenicity of M. grisea.