• 한국균학회소식:학술대회논문집
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• 2015.11a
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• pp.41-41
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• 2015

Oomycetes belong to the kingdom Straminipila, a remarkably diverse group which includes brown algae and planktonic diatoms, although they have previously been classified under the kingdom Fungi. These organisms have evolved both saprophytic and pathogenic lifestyles, and more than 60% of the known species are pathogens on plants, the majority of which are classified into the order Peronosporales (includes downy mildews, Phytophthora, and Pythium). Recent phylogenetic investigations based on DNA sequences have revealed that the diversity of oomycetes has been largely underestimated. Although morphology is the most valuable criterion for their identification and diversity, morphological species identification is time-consuming and in some groups very difficult, especially for non-taxonomists. DNA barcoding is a fast and reliable tool for identification of species, enabling us to unravel the diversity and distribution of oomycetes. Accurate species determination of plant pathogens is a prerequisite for their control and quarantine, and further for assessing their potential threat to crops. The mitochondrial cox2 gene has been widely used for identification, taxonomy and phylogeny of various oomycete groups. However, recently the cox1 gene was proposed as a DNA barcode marker instead, together with ITS rDNA. To determine which out of cox1 or cox2 is best suited as universal oomycete barcode, we compared these two genes in terms of (1) PCR efficiency for 31 representative genera, as well as for historic herbarium specimens, and (2) in terms of sequence polymorphism, intra- and interspecific divergence. The primer sets for cox2 successfully amplified all oomycete genera tested, while cox1 failed to amplify three genera. In addition, cox2 exhibited higher PCR efficiency for historic herbarium specimens, providing easier access to barcoding type material. In addition, cox2 yielded higher species identification success, with higher interspecific and lower intraspecific divergences than cox1. Therefore, cox2 is suggested as a partner DNA barcode along with ITS rDNA instead of cox1. Including the two barcoding markers, ITS rDNA and cox2 mtDNA, the multi-locus phylogenetic analyses were performed to resolve two complex clades, Bremia lactucae (lettuce downy mildew) and Peronospora effuse (spinach downy mildew) at the species level and to infer evolutionary relationships within them. The approaches discriminated all currently accepted species and revealed several previously unrecognized lineages, which are specific to a host genus or species. The sequence polymorphisms were useful to develop a real-time quantitative PCR (qPCR) assay for detection of airborne inoculum of B. lactucae and P. effusa. Specificity tests revealed that the qPCR assay is specific for detection of each species. This assay is sensitive, enabling detection of very low levels of inoculum that may be present in the field. Early detection of the pathogen, coupled with knowledge of other factors that favor downy mildew outbreaks, may enable disease forecasting for judicious timing of fungicide applications.

• ALGAE
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• v.35 no.3
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• pp.293-301
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• 2020

The applications of DNA barcoding have a wide range of uses, such as in taxonomic studies to help elucidate cryptic species and phylogenetic relationships and analyzing environmental samples for biodiversity monitoring and conservation assessments of species. After obtaining the DNA barcode sequences, sequence similarity-based homology analysis is commonly used. This means that the obtained barcode sequences are compared to the DNA barcode reference databases. This bioinformatic analysis necessarily implies that the overall quantity and quality of the reference databases must be stringently monitored to not have an adverse impact on the accuracy of species identification. With the development of next-generation sequencing techniques, a noticeably large number of DNA barcode sequences have been produced and are stored in online databases, but their degree of validity, accuracy, and reliability have not been extensively investigated. In this study, we investigated the extent to which the amount and types of erroneous barcode sequences were deposited in publicly accessible databases. Over 4.1 million sequences were investigated in three largescale DNA barcode databases (NCBI GenBank, Barcode of Life Data System [BOLD], and Protist Ribosomal Reference database [PR2]) for four major DNA barcodes (cytochrome c oxidase subunit 1 [COI], internal transcribed spacer [ITS], ribulose bisphosphate carboxylase large chain [rbcL], and 18S ribosomal RNA [18S rRNA]); approximately 2% of erroneous barcode sequences were found and their taxonomic distributions were uneven. Consequently, our present findings provide compelling evidence of data quality problems along with insufficient and unreliable annotation of taxonomic data in DNA barcode databases. Therefore, we suggest that if ambiguous taxa are presented during barcoding analysis, further validation with other DNA barcode loci or morphological characters should be mandated.

• Animal Systematics, Evolution and Diversity
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• v.37 no.4
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• pp.354-357
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• 2021

In Korean waters, the cirolanid isopod, Eurydice longiantennata Nunomura and Ikehara, 1985 has been reported only from the subtidal zone of Jeju island. We obtained the mitochondrial cytochrome c oxidase subunit I (COI) sequences of this species and determined the DNA barcoding data of E. longiantennata based on a genetic comparison of E. longiantennata and its congeners. The intra-specific genetic distance between the three COI sequences of E. longiantennata ranged from 0 to 0.6%. The inter-specific distances between E. longiantennata and other cirolanid isopods ranged from 24 to 33.2%. In this study, we provided the DNA information of E. longiantennata with a morphological diagnosis and images of the species.

• Animal Systematics, Evolution and Diversity
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• v.35 no.3
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• pp.156-159
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• 2019

The phyllodicd polychaete species, Nereiphylla hera Kato and Mawatari, 1999 is reported from the intertidal habitats of the eastern coast of South Korea. We determined the DNA barcoding region of the mitochondrial cytochrome c oxidase subunit I (COI) of N. hera and compared nucleotide variation with its congeners. The intra-specific genetic distance between the three COI sequences of N. hera was ranged from 0 to 0.4%. The inter-specific distances between N. hera and other Nereiphylla species ranged from 18.8 to 22.3%. In this study, we reported the first COI barcodes of N. hera with the morphologcial diagnosis and the photographs. These results would be helpful to understand taxonomy of Nereiphylla.

• Animal Systematics, Evolution and Diversity
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• v.38 no.2
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• pp.108-112
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• 2022

An aegid species, Rocinela niponia Richardson, 1909, is a Far Eastern species known from Korean and Japanese waters. In this study, mitochondrial cytochrome c oxidase subunit I (COI) sequences of R. niponia were determined based on four specimens collected from the subtidal zone of Chujado Island, South Korea. We compared DNA barcoding data of this species with its congeners. As a result, there was no intra-specific genetic distance between the four COI sequences of R. niponia. Inter-specific distances between R. niponia and other five aegid species ranged from 23.8% to 35.6%. Morphological diagnosis and images of R. niponia are also provided as a valuable contribution toward the identification of Rocinela species in further taxonomic and ecological studies.

• ALGAE
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• v.38 no.2
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• pp.127-139
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• 2023

Cryptic stages of diverse macroalgae present in natural substrata, "the bank of microscopic forms", were isolated into clonal cultures and identified based on both morphological characteristics and DNA barcoding. Approximately 120 clonal isolates from 308 natural substratum samples were collected from the entire coastline of Kuwait. Amongst these isolates, 77 (64%) were identified through DNA barcoding using the nuclear ribosomal small subunit, RuBisCO spacer (ITS2, tufa, rbcL, psaA, and psbA) and sequencing. Twenty-six isolates (34%) were identified in the division Chlorophyta, 18 (23%) as Phaeophyceae, and 33 (43%) as Rhodophyta. For all DNA sequences in this study, species-level cut off applied was ≥98% homology which depend entirely on the markers used. Three putative new records of Chlorophyta new for the Arabian Gulf were made: Cladophora laetevirens (Dillwyn) Kützing, Ulva torta (Mertens) Trevisan and Ulvella leptochaete (Huber) R. Nielsen, C. J. O'Kelly & B. Wysor in Nielsen, while Cladophora gracilis Kützing and Ulva ohnoi M. Hiraoka & S. Shimada are new records for Kuwait. For Phaeophyceae, Ectocarpus subulatus Kützing and Elachista stellaris Areschoug were new records for the Gulf and Kuwait. In the Rhodophyta, Acrochaetium secundatum (Lyngbye) Nägeli in Nägeli & Cramer, Ceramium affine Setchell & N. L. Gardner, Gelidium pusillum var. pakistanicum Afaq-Husain & Shameel and Dasya caraibica Børgesen are new records for the Gulf and Kuwait, while the red alga Stylonema alsidii (Zanardini) K. Drew is a new record for Kuwait. Several isolates identified corresponded to genera not previously reported in Kuwait and / or the Arabian Gulf, such as Porphyrostromium Trevisan, a new genus from the Bangiales, and two unidentified species for the Planophilaceae Škaloud & Leliaert. The isolates cultivated from substrata enhance understanding of the marine macroalgal diversity in the region and confirmed that the Germling Emergence Method is suitable for determining the actual diversity of a given study area through isolation from cryptic life-history phases.

• Mycobiology
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• v.41 no.4
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• pp.191-201
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• 2013

Distinguishing individual Russula species has been difficult due to extensive phenotypic plasticity and obscure morphological and anatomical discontinuities. Due to highly similar macroscopic features, such as the presence of a red-cap, species identification within the Russula subgenus Amoenula is particularly difficult. Three species of the subgenus Amoneula have been reported in Korea. We used a combination of morphology and three molecular markers, the internal transcribed spacer (ITS), 28S nuclear ribosomal large subunit (LSU), and RNA polymerase II gene (RPB2), for identification and study of the genetic diversity of Russula subgenus Amoenula in Korea. We identified only two species in Korea (R. mariae and R. violeipes); these two species were indistinguishable according to morphology and LSU, but were found to be reciprocally monophyletic species using ITS and RPB2. The markers, ITS, LSU, and RPB2, have been tested in the past for use as DNA barcoding markers, and findings of our study suggest that ITS and RPB2 had the best performance for the Russula subgenus Amoneula.

• Mycobiology
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• v.48 no.5
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• pp.331-340
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• 2020

The family Peronosporaceae, an obligate biotrophic group of Oomycota, causes downy mildew disease on many cultivated and ornamental plants such as beet, cucumber, grape, onion, rose, spinach, and sunflower. To investigate the diversity of Peronosporaceae species in Korea, we performed morphological analysis for dried plant herbariums with downy mildew infections by two largest genera, Peronospora and Plasmopara. As a result, it was confirmed that there are five species of Peronospora and two species of Plasmopara, which have been so far unrecorded in Korea, as well as rarely known in the world; Pl. angustiterminalis (ex Xanthium strumarium), Pl. siegesbeckiae (ex Siegesbeckia glabrescens), P. chenopodii-ambrosioidis (ex Chenopodium ambrosioides), P. chenopodii-ficifolii (ex Chenopodium ficifolium), P. clinopodii (ex Clinopodium cf. vulgare), P. elsholtziae (ex Elsholtzia ciliata), and P. lathyrina (ex Lathyrus japonicus). In addition, their phylogenetic relationship was inferred by molecular sequence analysis of ITS, LSU rDNA, and cox2 mtDNA. By rediscovering the seven missing species and barcoding their DNA sequences, this study provides valuable insights into the diversity and evolutionary studies of downy mildew pathogens.

• Animal Systematics, Evolution and Diversity
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• v.36 no.3
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• pp.228-231
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• 2020

Pseudohelice subquadrata (Dana, 1851) is endangered due to its restricted habitat; hence, it has been designated as a marine protected species and endangered species by law in Korea. It has been recorded only Jeju-do and Geomun-do, Republic of Korea. The present study, is the first report on a cytochrome c oxidase subunit I DNA barcode for P. subquadrata. The maximum intra-specific genetic distance among all P. subquadrata individuals was found to be 0.5%, whereas inter-genetic distance within the same genus was 17.2-21.5% compared with Helice tientsinensis (Rathbun, 1931), H. tridens (De Haan, 1835), H. epicure (Ng et al., 2018), and Helicana wuana (Rathbun, 1931). Our barcoding data can thus be used as reference for restoration and conservation studies on P. subquadrata, which are designated as marine protected species.

• Journal of Plant Biotechnology
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• v.48 no.3
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• pp.131-138
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• 2021

We reviewed current research trends for discriminating between species of the Angelica genus, a group of important medicinal plants registered in South Korea, China, and Japan. Since the registered species for medicinal purposes differ by country, they are often adulterated as well as mixed in commercial markets. Several DNA technologies have been applied to distinguish between species. However, one of the restrictions is insufficient single-nucleotide polymorphisms (SNPs) within the target DNA fragments; in particular, among closely-related species. Recently, amplification refractory mutation system (ARMS)-PCR and highresolution melting (HRM) curve analysis techniques have been developed to solve such a problem. We applied both technologies, and found they were able to discriminate several lines of Angelica genus, including A. gigas Nakai, A. gigas Jiri, A. sinensis, A. acutiloba Kitag, and Levisticum officinale. Furthermore, although the ITS region differs only by one SNP between A. gigas Nakai and A. gigas Jiri, both HRM and ARMS-PCR techniques were powerful enough to discriminate between them. Since both A. gigas Nakai and A. gigas Jiri are native species to South Korea and are very closely related, they are difficult to discriminate by their morphological characteristics. For practical applications of these technologies, further research is necessary with various materials, such as dried or processed materials (jam, jelly, juice, medicinal decoctions, etc.) in commercial markets.