• The Korean Journal of Mycology
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• v.46 no.3
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• pp.281-294
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• 2018

Molecular analysis using the internal transcribed spacer region sequences revealed that the strains used in this study, which were formerly identified as Panellus serotinus, are Panellus edullis. After Universal Fungal PCR Fingerprinting (UFPF) analysis, eight strains of P. edulis were divided into two groups. We conducted fundamental research on mycelial growth and sawdust cultivation to understand the cultural characteristics of eight wild P. edulis strains collected from Korean forests. All strains showed faster and denser mycelial growth on potato dextrose agar (PDA) than on other media (malt extract agar, Sabouraud dextrose agar). Optimal conditions for mycelial growth were: $20^{\circ}C$ on PDA, $25^{\circ}C$ on potato dextrose broth (PDB), and pH 5~8 on PDB at $25^{\circ}C$. Two strains (NIFoS 2407, 3993) were selected as excellent strains based on mycelial growth and density on PDA. NIFoS 2792 showed high cellulase activities on carboxymethyl cellulose (CMC) agar, and NIFoS 2387 and 2804 exhibited high laccase activities on ABTS-containing agar media. The mycelial growth of P. edulis was the fastest on Quercus acutissima and Q. mongolica sawdust media, and mycelial density was the highest on Quercus spp. sawdust-containing media. Sawdust cultivation of P. edulis was successful. The conditions were 80~85 days of cultivation period after spawn inoculation, 10~11 days for primordial formation at $17{\sim}18^{\circ}C$, and 15~20 days for fruiting growth. NIFoS 2804 and 3993 were selected as good strains in terms of cultivation period and mushroom production. These results could be useful for the artificial cultivation of P. edulis.

• Asian Journal of Turfgrass Science
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• v.20 no.1
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• pp.65-76
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• 2006

Scz1, an isolate of Sclerotinia homoeocarpa, was recently reported as a novel pathogen responsible for dollar spot disease in Zoysiagrass, a warm season turfgrass. Scz1 possessed different characteristics on mycelial pigment, mycelial affinity and host pathogenecity compared to those of Scb1, a typical isolate, obtained from creeping bentgrass, a cool season turfgrass. In this study, only three isolates, Scz1, Scz2(another analogous isolate of Sclerotinia homoeocarpa from zoysiagrass), and Scb1, were examined at the molecular level using the internal transcribed spacer(ITS) and random amplified polymorphic DNA(RAPD) assays to verify their identification and genetic variation. As a result of ITS assay, partial ITS sequences of three isolates showed 94-97% similarity with a standardized ITS sequence of S. homoeocarpa registered on BLAST. In the analysis of RAPD, range value through similarity matrix was 0.167 between Scz1 and Scb1, 0.139 between Scz2 and Scb1, and 0.713 between Scz1 and Scz2, respectively. Furthermore, tendegram analysis indicated that Scz1 and Scz2, unlike Scb1, were clustered together as accompanying a high genetic similarity. In in vitro fungicide bioassay, $EC_{50}$ value representing the sensitivity degree to propiconazole, a well-known fungicide for dollar spot disease, was 0.012 ${\mu}g/ml$ for Sczl, 0.003 ${\mu}g/ml$ for Scz2, and 0.030 ${\mu}g/ml$ for Scb1. From all data taken, we concluded that both Scz1 and Scz2 belonged to one group of S. homoeocarpa, since they exhibit the same host range and high level of genetic similarity, whereas their chemical competences to a fungicide were different. This study would provide further approach for assessing genetic diversity of S. homoeocarpa isolates as well as characterizing individual isolate against chemical exposure.

• Korean journal of applied entomology
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• v.56 no.4
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• pp.377-385
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• 2017

Estimates of evolutionary sequence divergence and inference of a phylogenetic tree for eight delphacid planthopper species were based on the full-length nucleotide sequence of the internal transcribed spacer 2 (ITS2) region. Size of the ITS2 DNA sequence varied from 550 bp in Sogatella furcifera to 699 bp in Nilaparvata muiri. Nucleotide sequence distance ($d{\pm}S.E.$) was lowest between N. muiri and N. bakeri ($0.001{\pm}0.001$), and highest between Ecdelphax cervina and Stenocranus matsumurai ($0.579{\pm}0.021$). Sequence distance between N. lugens and other planthoppers ranged from $0.056{\pm}0.008$ (N. muiri) to $0.548{\pm}0.021$ (S. matsumurai). In the neighbor-joining phylogenetic tree, all planthoppers were clustered separately into a species group, except N. muiri and N. bakeri. The ITS2 nucleotide sequence of N. lugens was used to design four loop-mediated isothermal amplification (LAMP) primer sets (BPH-38, BPH-38-1, BPH-207, and BPH-92) for N. lugens species-specific detection. After the LAMP reaction of three rice planthoppers, N. lugens, S. furcifera, and Laodelphax striatellus, with the four LAMP primer sets for 60 min at $65^{\circ}C$, LAMP products were observed in the genomic DNA of N. lugens only. In the BPH-92 LAMP primer set, the fluorescence relative to that of the negative control differed according to the amount of DNA (0.1 ng, 10 ng, and 100 ng) and incubation duration (20 min, 30 min, 40 min, and 60 min). At $65^{\circ}C$ incubation, the difference was clearly observed after 40 min with 10 ng and100 ng, but with a 60-min incubation period, the minimum DNA needed was 0.1 ng. However, there was little difference in fluorescence among all DNA amounts tested with 20 or 30 min incubations.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.22 no.1
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• pp.31-44
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• 2017

Pfiesteria piscicida is one of heterotrophic dinoflagellate having toxic metaboliges, and it is difficult to detect and quantify this dinoflagellate via light microscope due to small size and morphological similarity with Pfiesteria-like dinoflagellate (PLD) species. Alternatively, we developed quantitative real-time PCR assay based on EvaGreen and determined field accessibility throughout the investigation of distribution in the entire Korean coastal waters and population dynamics in Shihwa Lake. The P. piscicida-specific primers based on internal transcribed spacer 1 (ITS 1) were designed and the specificity of primers was confirmed by PCR with other genomic DNAs which have genetic similarity with target species. Through real-time PCR assay, a standard curve which had a significant linear correlation between log cell number and $C_T$ value ($r^2{\geq}0.999$) and one informative melting peak ($88^{\circ}C$) were obtained. These results implies that developed real-time PCR can accurately detect and quantify P. piscicida. Throughout the field applications of real-time PCR assay, P. piscicida was distributed in western (Mokpo and Kimje) and easthern (Gangneng) Korean coastal water even though light microscopy failed to identify P. piscicida. In the investigation of population dynamics in Shihwa Lake, the density of P. piscicida was peaked in June, July and August 2007 at St. 1 where salinity (${\leq}15psu$) was lower than the other 2 sites. In this study, we successed to develop EvaGreen bassed real-time PCR for detection and quantification of P. piscicida in fields, so this developed assay will be useful for various ecological studies in the future.

• Korean Journal of Microbiology
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• v.55 no.3
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• pp.234-241
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• 2019

An intensive interaction between yeasts and insects has highlighted their relevance for attraction to food and for the insect's development and behavior. Yeast associated in the gut of insects secretes cellulase which aided in the food digestion (cellulose degradation). Three strains of cellulose-degrading yeast were isolated from the gut of adult grasshoppers collected in Gyeonggi Province, South Korea. The strains $ON22^T$, $G10^T$, and $G15^T$, showed positive cellulolytic activity in the carboxymethyl cellulose (CMC)-plate assay. The phylogenetic tree based on sequence analysis of D1/D2 domains of the large subunit rRNA gene and the internal transcribed spacer (ITS) regions revealed that the strains $ON22^T$ (100 and 98.4% sequence similarities in D1/D2 domains and ITS) and $G10^T$ (99.8 and 99.5% in D1/D2 domain and ITS region) were most closely related to the species Moesziomyces aphidis JCM $10318^T$; $G15^T$ (100% in D1/D2 domains and ITS) belongs to the species Moesziomyces antarcticus JCM $10317^T$, respectively. Morphology and biochemical test results are provided in the species description. Cellulase with its massive applicability has been used in various industrial processes such as biofuels like bioethanol productions. Therefore, this is the first report of the cellulolytic yeast strains $ON22^T$, $G10^T$, and $G15^T$ related to the genus Moesziomyces in the family Ustilaginaceae (Ustilaginales), in Korea.

• Korean Journal of Microbiology
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• v.54 no.4
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• pp.362-368
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• 2018

Grasshoppers play vital role in the digestion of photosynthetically fixed carbons. With the aid of intestinal microflora, the grasshopper can degrade leaves constituents such as cellulose and hemicellulose. The purpose of this study was to examine cellulolytic yeast isolates from the gut of grasshoppers collected in Gyeonggi Province, South Korea. Among the yeast isolates, ON2, ON17 (two strains), and ON6 (one strain) showed positive cellulolytic activity in the CMC-plate assay. The sequence analyses of D1/D2 domains of the large subunit rDNA gene and the internal transcribed spacer (ITS) regions revealed that the strains ON2 and ON17 were most closely related to Papiliotrema aspenensis CBS $13867^T$ (100%, sequence similarity in D1/D2 domains; 99.4% sequence similarity in ITS) and strain ON6 related to Saitozyma flava (100% in D1/D2 domains; 99.0% in ITS). All these three yeast strains are capable of degrading cellulose; therefore, the members of endosymbiotic yeasts may produce their own enzymes for carbohydrate degradation and convert mobilized sugar monomers to volatile fatty acids. Thus, the endosymbiotic yeast strains ON2, ON17 (represents the genus Papilioterma) and ON6 (Saitozyma) belonging to the family Tremellomycetes, are unreported strains in Korea.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.105-110
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• 2008

We have proposed a new structure of poly-silicon thin film transistor(TFT) which was fabricated the LDD region using doping oxide with graded spacer by etching shape retio. The devices of n-channel poly-si TFT's hydrogenated by $H_2$ and $HT_2$/plasma processes are fabricated for the devices reliability. We have biased the devices under the gate voltage stress conditions of maximum leakage current. The parametric characteristics caused by gate voltage stress conditions in hydrogenated devices are investigated by measuring /analyzing the drain current, leakage current, threshold voltage($V_{th}$), sub-threshold slope(S) and transconductance($G_m$) values. As a analyzed results of characteristics parameters, the degradation characteristics in hydrogenated n-channel polysilicon TFT's are mainly caused by the enhancement of dangling bonds at the poly-Si/$SiO_2$ interface and the poly-Si Brain boundary due to dissolution of Si-H bonds. The structure of novel proposed poly-Si TFT's are the simplity of the fabrication process steps and the decrease of leakage current by reduced lateral electric field near the drain region.

• Korean Journal of Plant Taxonomy
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• v.37 no.2
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• pp.115-129
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• 2007

Using internal transcribed spacer (ITS) sequences and inter-simple sequence repeats (ISSRs) data, genetic diversity of a rare species, Hibiscus hamabo Siebold & Zucc. was examined for 3 populations in Jeju Island, Korea. A total of 14 nucleotide (excluding 3 ambiguous nucleotide) site variation in the ITS was observed from 18 individuals (Population 1, Hadori), which differed up to 13 bp in pair-wise comparison. On the contrary, the ITS sequences of all individuals in Populations 2 and 3 were identical. Genetic diversity estimates including Nei's gene diversity (h) generated by ISSR data were substantially high in Population 1 compared to other two populations. Low genetic variation in Populations 1 and 2 is considered due to genetic drift (bottleneck effect) and limited gene flow in these populations. Considering the differences in genetic diversity, protection of the Population 1(Hadori) is very critical for in situ conservation of Hibiscus hamabo in Korea. If ex situ conservation is required, making the full use of Population 1 will be most efficient.

• Korean Journal of Plant Taxonomy
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• v.43 no.1
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• pp.46-55
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• 2013

The purpose of this study is to review the taxonomic position of Taxus cuspidata var. latifolia endemic to Ulleung Island with related taxa T. cuspidata var. cuspidata, T. caespitosa, and T. cuspidata var. nana based on external morphological characters and DNA barcoding study. T. cuspidata var. latifolia was similar to T. cuspidata var. cuspidata in the arbor, straight trunk, and symmetric arrangement of leaf. But the unique differences between T. cuspidata var. latifolia and T. cuspidata var. cuspidata were leaf size and the exposure of seed from aril. Additionally, sequences of four chloroplast DNA regions including matK, rbcL, trnL intron and trnL-trnF spacer regions were analyzed. Korean Taxus species and their related taxon T. cuspidata var. nana were strongly supported as a monophyletic group in neighbor-joining analysis. Taxus cuspidata var. latifolia showed 100% sequence identity to related taxa. Korean endemic T. caespitosa is also distinguishable from related taxa by prostrate stems and spiral arrangement of leaf. The examinations of external morphology and DNA barcoding study suggest that the taxonomic position of T. cuspidata var. latifolia should be maintained as a variety of T. cuspidata.

• Weed & Turfgrass Science
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• v.2 no.1
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• pp.88-94
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• 2013

Brown patch caused by Rhizoctonia solani AG-1 IB occurred on Kentucky bluegrass during late May through early October 2010 at golf course in Gyeongbuk Province, Korea. Disease symptoms on the turfgrass for spring season were leaf blights dying from the leaf tip, which appeared patches of brown color in the field. However, it appeared patches of dark brown color or gray brown color in fall. The fungus (B-7 isolate) of brown patch was isolated from the diseased leaf tissue and cultured on potato-dextrose agar (PDA) for identification. The young hyphae had acute angular branching and few septa and mature hyphal branches showed about 90-degree angles and development of monilioid cells, which were morphologically identical to Rhizoctonia solani AG-1 IB reported previously. DNA sequences of ribosomal RNA gene (internal transcribed spacer) of the fungus were homologous with similarity of 99% to those of Rhizoctonia solani AG-1 IB isolates in GenBank database, confirming the identity of the causal agent of the disease. Pathogenicity of the fungus was also confirmed on the creeping bentgrass and Kentucky bluegrass by Koch's postulates. This is the first report of brown patch on Kentucky bluegrass caused by Rhizoctonia solani AG-1 IB in Korea.