• 한국자기공명학회논문지
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• 제24권4호
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• pp.123-128
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• 2020

All plants in natural ecosystems are living in symbiosis with endophytes. Recently, there has been an increasing interest in endophytes since these organisms can interact with the hosts and produce various structurally or biologically interesting molecules. This study aimed to identify these molecules from endophytes. Chemical investigation of Climacium dendroides-derived fungus Talaromyces sp. resulted in the isolation of two diphenyl ether derivatives, purpactin A (1) and penicillide (2), and two steroids, dankasterone A (3) and calvasterol B (4). The structures of the compounds were identified via extensive spectroscopic and spectrometric methods. Four compounds did not show any antioxidative activities in the on-line antioxidant activity screening system.

• Mycobiology
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• 제43권2호
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• pp.137-149
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• 2015

In the search for novel potent fungi-derived bioactive compounds for bioinsecticide applications, crude ethyl acetate culture filtrate extracts from 110 mangrove fungal endophytes were screened for their toxicity. Toxicity tests of all extracts against brine shrimp (Artemia salina) larvae were performed. The extracts with the highest toxicity were further examined for insecticidal activity against Spodoptera litura larvae and acetylcholinesterase (AChE) inhibition activity. The results showed that the extracts of five isolates exhibited the highest toxicity to brine shrimp at 50% lethal concentration ($LC_{50}$) values of 7.45 to 10.24 ppm. These five fungal isolates that obtained from Rhizophora mucronata were identified based on sequence data analysis of the internal transcribed spacer region of rDNA as Aspergillus oryzae (strain BPPTCC 6036), Emericella nidulans (strains BPPTCC 6035 and BPPTCC 6038), A. tamarii (strain BPPTCC 6037), and A. versicolor (strain BPPTCC 6039). The mean percentage of S. litura larval mortality following topical application of the five extracts ranged from 16.7% to 43.3%. In the AChE inhibition assay, the inhibition rates of the five extracts ranged from 40.7% to 48.9%, while eserine (positive control) had an inhibition rate of 96.8%, at a concentration of 100 ppm. The extracts used were crude extracts, so their potential as sources of AChE inhibition compounds makes them likely candidates as neurotoxins. The high-performance liquid chromatography profiles of the five extracts differed, indicating variations in their chemical constituents. This study highlights the potential of culture filtrate ethyl acetate extracts of mangrove fungal endophytes as a source of new potential bioactive compounds for bioinsecticide applications.

• The Plant Pathology Journal
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• 제38권4호
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• pp.313-322
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• 2022

Seed-borne pathogens in crops reduce the seed germination rate and hamper seedling growth, leading to significant yield loss. Due to the growing concerns about environmental damage and the development of resistance to agrochemicals among pathogen populations, there is a strong demand for eco-friendly alternatives to synthetic chemicals in agriculture. It has been well established during the last few decades that plant seeds harbor diverse microbes, some of which are vertically transmitted and important for plant health and productivity. In this study, we isolated culturable endophytic bacteria and fungi from soybean seeds and evaluated their antagonistic activities against common bacterial and fungal seed-borne pathogens of soybean. A total of 87 bacterial isolates and 66 fungal isolates were obtained. Sequencing of 16S rDNA and internal transcribed spacer amplicon showed that these isolates correspond to 30 and 15 different species of bacteria and fungi, respectively. Our antibacterial and antifungal activity assay showed that four fungal species and nine bacterial species have the potential to suppress the growth of at least one seed-borne pathogen tested in the study. Among them, Pseudomonas koreensis appears to have strong antagonistic activities across all the pathogens. Our collection of soybean seed endophytes would be a valuable resource not only for studying biology and ecology of seed endophytes but also for practical deployment of seed endophytes toward crop protection.

• 한국초지조사료학회지
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• 제42권3호
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• pp.201-207
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• 2022

Fescues, which are widely cultivated as grasses and forages around the world, are often naturally infected with the endophyte, Epichloë. This fungus, transmitted through seeds, imparts resistance to drying and herbivorous insects in its host without causing any external damage, thereby contributing to the adaptation of the host to the environment and maintaining a symbiosis. However, some endophytes, such as E. coenophialum synthesize ergovaline or lolitrem B, which accumulate in the plant and impart anti-mammalian properties. For example, when livestock consume excessive amounts of grass containing toxic endophytes, problems associated with neuromuscular abnormalities, such as convulsions, paralysis, high fever, decreased milk production, reproductive disorders, and even death, can occur. Therefore, pre-inoculation with non-toxic endogenous fungi or management with endophyte-free grass is important in preventing damage to livestock and producing high-quality forage. To date, the diagnosis of endophytes has been mainly performed by observation under a microscope following staining, or by performing an immune blot assay using a monoclonal antibody. Recently, the polymerase chain reaction (PCR)-based molecular diagnostic method is gaining importance in the fields of agriculture, livestock, and healthcare given the method's advantages. These include faster results, with greater accuracy and sensitivity than those obtained using conventional diagnostic methods. For the diagnosis of endophytes, the nested PCR method is the only available option developed; however, it is limited by the fact that the level of toxic alkaloid synthesis cannot be estimated. Therefore, in this study, we aimed to develop a triplex real-time PCR diagnostic method that can determine the presence or absence of endophyte infection using DNA extracted from seeds within 1 h, while simultaneously detecting easD and LtmC genes, which are related to toxic alkaloid synthesis. This new method was then also applied to real field samples.

• Mycobiology
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• 제42권2호
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• pp.100-108
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• 2014

Twelve plant species were collected from the east coast of Korea to identify culturable endophytes present in their roots. The fungal internal transcribe spacer (ITS) region (ITS1-5.8SrRNA-ITS2) was used as a DNA barcode for identification of fungi. A total of 194 fungal strains were identified and categorized into 31 genera. The genus Penicillium accounted for the largest number of strains, followed by the genus Aspergillus. Furthermore, using 5 statistical methods, the diversity indices of the fungi were calculated at the genus level. After comprehensive evaluation, the endophytic fungal group from Phragmites australis ranked highest in diversity analyses. Several strains responsible for plant growth and survival (Penicillium citrinum, P. funiculosum, P. janthinellum, P. restrictum, and P. simplicissimum), were also identified. This study provides basic data on the sheds light on the symbiotic relationship between coastal plants and fungi.

• 한국균학회지
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• 제45권4호
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• pp.355-361
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• 2017

본 연구는 전라북도 진도에서 자란(Bletilla striata), 강원도 정선군 함백산에서 감자난초(Oreorchis patens)와 은대난초(Cephalanthera longibracteata)의 뿌리에서 내생균을 분리하고 이들의 형태 및 분자생물학적 방법을 통해 동정하였다. 각 균주의 형태학적 특징을 분석하기 위해 포자의 모양과 특징을 관찰하였고, 분자생물학적 동정을 위해 ITS1F와 ITS4 primer를 이용하여 internal transcribed spacer (ITS) 및large subunit (LSU) rDNA영역을 분석하였다. 그 결과 Phialocephala bamuru, Coniochaeta mutabilis, Phialophora foetens, Calonectria Canadensis, Neonectria ramulariae 5종의 국내 미기록 내생균이 동정되어 이를 보고하고자 한다.

• Journal of Microbiology and Biotechnology
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• 제20권3호
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• pp.630-636
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• 2010

A survey of the endangered orchid Orchis militaris populations was carried out in north-eastern Italy. The occurrence of fungal root endophytes was investigated by light and electron microscopies and molecular techniques. Two main sites of presence were individuated in the Euganean Hills, differing as to the percentage of flowering individuals and of capsules completing maturity. Fluorescence microscopy revealed an intracellular cortical colonization by hyphal pelotons. Two ITS PCR products co-amplified. Sequencing revealed for the former an identity and a high similarity (99%) with a Tulasnellaceae (Basidiomycota) fungus found within tissues of the same host in independent studies in Hungary and Estonia, suggesting an interesting case of tight specificity throughout the Eurosiberian home range. The second amplicon had 99% similarity with Tetracladium species (Ascomycota) recently demonstrated as potential endophytes. TEM revealed two different hyphal structures. Double fungal colonization appears to occur in Orchis militaris and the possible requirement of a specific fungal partner throws light on the causes of this plant's rarity and threatened status.

• The Plant Pathology Journal
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• 제38권5호
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• pp.490-502
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• 2022

Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial leaf blight (BLB) disease in rice (Oryza sativa L.) and it is among the most destructive pathogen responsible for severe yield losses. Potential bacterial biocontrol agents (BCAs) with plant growth promotion (PGP) abilities can be applied to better manage the BLB disease and increase crop yield, compared to current conventional practices. Thus, this study aimed to isolate, screen, and identify potential BCAs with PGP abilities. Isolation of the BCAs was performed from internal plant tissues and rhizosphere soil of healthy and Xoo-infected rice. A total of 18 bacterial strains were successfully screened for in vitro antagonistic ability against Xoo, siderophore production and PGP potentials. Among the bacterial strains, 3 endophytes, Bacillus sp. strain USML8, Bacillus sp. strain USML9, and Bacillus sp. strain USMR1 which were isolated from diseased plants harbored the BCA traits and significantly reduced leaf blight severity of rice. Simultaneously, the endophytic BCAs also possessed plant growth promoting traits and were able to enhance rice growth. Application of the selected endophytes (BCAs-PGP) at the early growth stage of rice exhibited potential in suppressing BLB disease and promoting rice growth.

• 아시안잔디학회지
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• 제23권1호
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• pp.163-176
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• 2009

자생화본과 식물에서 자연적으로 생기는 엔도파이트 분포의 연구는 엔도파이트 공생에 대한 이해와 재배식물에서의 엔도파이트의 잇점에 대하여 중요하다. 본 연구는 중국 유난, 구이죠우, 시촨지역에서 자생하는 페스큐로부터 엔도파이트를 조사하고, 그 지역에서 널리 식재되는 잔디형 페스큐와의 융화에 대하여 연구하는데 목표를 두었다. 현장의 현미경 관찰 결과628개체의 sheep fescue 중 421개체가 엽초조직에서 엔도파이트가 동정되었다. 페스큐종에서 3개는 종자에서, 90개의 엔도파이트 분리체가 수집된 종자의 유묘에서 수집되었다. sheep fescue와 stapfii 페스큐의 엔도파이트는 Neotyphodium typhinum와 Neotyphodium starii로 각각 동정되었다. Little Hero, Sub Boy, Eldorado, Arid III, Millennium, Crossfire, 그리고 Fawn 톨페스큐 7품종에서 위 2종의 균류의 융화성을 조사한 결과, N. typhinum 나 N. typhinum and N. starii는 'Sun Boy'와 'Eldorado'에서 가장 높은 접종율을 보였다. 톨페스큐 품종과 엔도파이트 타입과의 접종에서 매우 높은 유의성의 교호 효과를 보였다.

• Mycobiology
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• 제40권4호
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• pp.231-235
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• 2012

Fungal endophytes are microfungi that live in plants without causing apparent symptoms of infection. This study was conducted to identify endophytic fungi isolated from leaves of coniferous trees in Bohyeon Mountain of Korea. We collected leaves of two species of coniferous trees, Pinus densiflora and Pinus koraiensis, from 11 sites in the study area. A total 58 isolates were obtained and identified using molecular and morphological characteristics. Four species of endophytic fungi were isolated from P. densiflora: Lophodermium conigenum, Leotiomycetes sp., Septoria pini-thunbergii, and Polyporales sp., while two fungal species were isolated from P. koraiensis: Eurotiomycetes sp. and Rhytismataceae sp. The most frequently isolated species were L. conigenum and S. pini-thunbergii.