470 results on '"Young-Joon Choi"'
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2. Designing A Novel Primer Set for GAPDH Gene to Enhance Taxonomic and Phylogenetic Studies of Golovinomyces Species
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Jun Hyuk Park and Young-Joon Choi
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New primers ,obligate biotroph ,phylogenetic marker ,powdery mildew ,Botany ,QK1-989 - Abstract
Golovinomyces (Erysiphaceae, Ascomycota) is an obligate plant pathogenic group causing powdery mildew on diverse angiosperm plants, including economically significant crops. Despite advancements in the taxonomy and phylogeny of Golovinomyces species using ribosomal DNA markers (ITS and LSU), several taxonomic issues remain unresolved. Previously, the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene, which exhibits higher nucleotide variation, has been proposed as an additional marker for powdery mildew species. In this study, we designed a new primer set (GoGPD-F and GoGPD-R) to improve the PCR success and efficiency of the GAPDH gene across various Golovinomyces species and dried herbarium specimens. The primers were successful in amplifying and sequencing the GAPDH gene in sixteen Golovinomyces species, including six species not previously registered in GenBank and two undescribed species. This development is a significant contribution to future research on the identification, taxonomy, and phylogeny of Golovinomyces species, offering a more robust tool for resolving existing taxonomic issues.
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- 2024
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3. Yearly Update of the List of Plant Diseases in Korea (6.2 Edition, 2024)
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Jaehyuk Choi, Seon-Hee Kim, Young-Joon Choi, Gyoung Hee Kim, Ju-Yeon Yoon, Byeong-Yong Park, Hyun Gi Kong, Soonok Kim, Sekeun Park, Chang-Gi Back, Hee-Seong Byun, Jang Kyun Seo, Jun Myoung Yu, Dong-Hyeon Lee, Mi-Hyun Lee, Bong Choon Lee, Seung-Yeol Lee, Seungmo Lim, Yongho Jeon, Jaeyong Chun, Insoo Choi, In-Young Choi, Hyo-Won Choi, Jin Sung Hong, and Seung-Beom Hong
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list of plant diseases in korea ,nomenclature ,online database ,plant disease ,Agriculture (General) ,S1-972 - Abstract
Since 2009, the Korean Society of Plant Pathology has established the Committee on Common Names of Plant Disease to systematically review and determine plant disease names and related terminologies. The committee published the 6th edition of the List of Plant Diseases in Korea (LPDK) in 2022, and the list has been made publicly accessible online. The online database has significantly enhanced user accessibility, expedited update processes, and improved interoperability with other databases. As a result, the 6.1 edition of the list was released by online LPDK in 2023, detailing new disease names added over the preceding year and revisions to existing names. Subsequently, in 2024, the 6.2 edition was published, encompassing 6,765 diseases caused by 2,503 pathogen taxa across 1,432 host species. The public release of the online database has, however, introduced several challenges and tasks. Addressing these issues necessitates the development of modern, standardized nomenclature guidelines and a robust system for the registration of new disease names. Open communication and collaboration among the diverse members of the Korean Society of Plant Pathology are required to ensure the reliability of the LPDK.
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- 2024
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4. Emergence and Potential Spread of Rust Disease on Wisteria floribunda and Corydalis incisa Influenced by Climate Change in Korea
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Jae Sung Lee, Ji-Hyun Park, Young-Joon Choi, and Hyeon-Dong Shin
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Ochropsora kraunhiae ,wisteria rust ,alternate host ,climate change ,predictive model ,Botany ,QK1-989 - Abstract
Global climate change influences the emergence, spread, and severity of rust diseases that affect crops and forests. In Korea, the rust diseases that affect Wisteria floribunda and its alternate host Corydalis incisa are rapidly spreading northwards. Through morphological, molecular, phylogenetic, and pathogenicity approaches, Neophysopella kraunhiae was identified as the causal agent, alternating between the two host plants to complete its life cycle. Using the maximum entropy model (Maxent) under shared socioeconomic pathways (SSPs), the results of this study suggest that by the 2050s, C. incisa is likely to extend its range into central Korea owing to climate shifts, whereas the distribution of W. floribunda is expected to remain unchanged nationwide. The generalized additive model revealed a significant positive correlation between the presence of C. incisa and the incidence of rust disease, highlighting the role that climate-driven expansion of this alternate host plays in the spread of N. kraunhiae. These findings highlight the profound influence of climate change on both the distribution of a specific plant and the disease a rust fungus causes, raising concerns about the potential emergence and spread of other rust pathogens with similar host dynamics.
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- 2024
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5. Taxonomy, Phylogeny, and Host Expansion of Powdery Mildew Fungi Parasitic to Veronica Species
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Jun Hyuk Park, Young-Joon Choi, and Hyeon-Dong Shin
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Golovinomyces cichoracearum ,host expansion ,phylogeny ,Podosphaera fuliginea ,Veronica kiusiana ,Botany ,QK1-989 - Abstract
AbstractPowdery mildew is a prevalent fungal disease that affects various Veronica spp. (Plantaginaceae), caused by species in the genera Podosphaera and Golovinomyces (Erysiphales). There have been recent taxonomic changes in these groups and ongoing disease occurrence on a range of Veronica species previously unrecognized as hosts; however, the pathogen found in Korea remains unidentified. This study aimed to identify the causative agent of powdery mildew on Veronica spp. in Korea through molecular phylogenetic analysis of internal transcribed spacer (ITS) and large subunit (LSU) sequences of rDNA and morphological examination. Our study identified Golovinomyces bolayi as the sole pathogen affecting all nine Veronica species in Korea and confirmed that G. cichoracearum s. str., which was previously identified as the pathogen, was not the causal agent. These results expand the known host range of G. bolayi, including the addition of five Veronica species in Korea: V. hederifolia, V. kiusiana var. glabrifolia, V. longifolia, V. polita, and V. serpyllifolia. Notably, V. kiusiana has been added as a new global host of powdery mildew. These findings substantially enhance our understanding of the taxonomy of powdery mildew pathogens on Veronica species and provide valuable insights into their evolutionary host expansion.
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- 2024
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6. Introduction of List of Plant Diseases in Korea 6.1st Edition (2023 Revised Version)
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Seon-Hee Kim, Jaehyuk Choi, Young-Joon Choi, Byeong-Yong Park, Su-Heon Lee, Gyoung Hee Kim, Hyun Gi Kong, Donggun Kim, Soonok Kim, Youngho Kim, Chang-Gi Back, Hee-Seong Byun, Jang Kyun Seo, Jun Myoung Yu, Ju-Yeon Yoon, Dong-Hyeon Lee, Seung-Yeol Lee, Seungmo Lim, Yongho Jeon, Jaeyong Chun, Insoo Choi, In-Young Choi, Hyo-Won Choi, Jin Sung Hong, and Seung-Beom Hong
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common name ,host ,pathogen ,plant disease ,reference ,Agriculture (General) ,S1-972 - Abstract
More than a year has passed after the 6th edition of ‘List of Plant Diseases in Korea (LPDK)’ was published in April 2022. The 6.1st edition (2023) of List of Plant Diseases in Korea was made by correcting errors found in the 6th edition of list and adding new diseases reported after the 6th edition. There were 397 corrections from the 6th edition, most of which were simple spelling errors or minor issues. However, 12 diseases were deleted due to duplication or unclear literature proof, and 2 diseases had their diseases’ common names changed. We added 158 diseases that were reported before 2021 but not included in the 6th edition, or reported after the 6th edition. After all, 146 diseases were added to the 6,534 diseases in the 6th edition, resulting in a total of 6,680 diseases in the 6.1st edition. Thirty host taxa were also added, increasing the number from 1,390 in the 6th edition to 1,420 in the 6.1st edition. Pathogens were also added to 62 taxa, from 2,400 in the 6th edition, bringing the total to 2,462 taxa in the 6.1st edition. Ultimately, the 6.1st edition (2023) of ‘The List of Plant Diseases in Korea’ contains 6,680 diseases caused by pathogens of 2,462 taxa on 1,420 hosts. The 6.1st edition is not printed as a book, but is provided through the online ‘List of Plant Diseases in Korea’ (https://genebank. rda.go.kr/kplantdisease.do).
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- 2023
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7. Morphology, Molecular Phylogeny, and Fungicide Sensitivity of Phytophthora nagaii and P. tentaculata in Korea
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Seung Hyun Lee, Bora Nam, Dong Jae Lee, and Young-Joon Choi
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Diversity ,oomycetes ,plant pathogen ,resistance ,Botany ,QK1-989 - Abstract
AbstractPhytophthora species, classified under Oomycota, cause significant damage to various crops and trees. The present study introduced Phytophthora species, P. nagaii and P. tentaculata, new to Korea, which pose notable risks to their respective host plants. Our research provided a comprehensive description of these species taking into account their cultural features, morphological characteristics, and molecular phylogenetic analysis using the internal transcribed spacer rDNA region and cytochrome c oxidase subunit mtDNA genes (cox1 and cox2) sequences. In addition, this study first evaluated the sensitivity of P. nagaii and P. tentaculata to five anti-oomycete fungicides, finding both species most responsive to picarbutrazox and P. tentaculata resistant to fluazinam. The data can guide targeted treatment strategies and offer insights into effective control methods. The findings expand our understanding of the diversity, distribution, and management of Phytophthora species in Korea.
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- 2023
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8. New Finding of Golovinomyces salviae Powdery Mildew on Glechoma longituba (Lamiaceae), Besides Its Original Host Salvia spp.
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In-Young Choi, Lamiya Abasova, Joon-Ho Choi, Young-Joon Choi, and Hyeon-Dong Shin
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erysiphaceae ,golovinomyces biocellatus ,gapdh (glyceraldehyde-3-phosphate dehydrogenase) ,its (internal transcribed spacer) ,lsu (large subunit) ,multigene analysis ,Biology (General) ,QH301-705.5 - Abstract
The Golovinomyces biocellatus complex is known to consist of powdery mildew from the Golovinomyces genus, associated with host plants from the Lamiaceae family. Recent molecular phylogenetic analyses have resolved the taxonomic composition of this complex, and Golovinomyces biocellatus sensu stricto is considered to be a pathogen of Glechoma species, globally. However, this paper presents a new finding of Golovinomyces salviae on Glechoma longituba, besides its original host species of Salvia. This information was inferred by molecular phylogenetic analyses from the multi-locus nucleotide sequence dataset of intergeneric spacer (IGS), internal transcribed spacer (ITS), large subunit (LSU) of rDNA, and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene. Further, the asexual morphology of this fungus is described and illustrated.
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- 2023
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9. Leaf Blight Caused by Curvularia intermedia on the Invasive Weed Lactuca serriola in Korea
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Jin A Lee, Seon Young Lee, and Young-Joon Choi
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biological control ,gpd (glyceraldehyde-3-phosphate dehydrogenase) ,lactuca scariola ,prickly lettuce ,Biology (General) ,QH301-705.5 - Abstract
Prickly lettuce (Lactuca serriola), an invasive annual plant, poses a significant threat to the agricultural systems of many countries, including Korea. In 2020, leaf blight symptoms were observed in the prickly lettuce populations of various farms across Korea. Detailed morphological and molecular sequence analyses revealed that the disease was caused by the fungus, Curvularia intermedia. A pathogenicity test confirmed that the fungus can cause the same symptoms in healthy prickly lettuce, thereby fulfilling Koch’s postulates. To the best of our knowledge, this is the first report of C. intermedia causing leaf blight on L. serriola in Korea, suggesting its potential as a biocontrol agent for this weed. However, further investigations are necessary to determine its ecological impact to prevent any nontarget effects.
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- 2023
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10. Identification and Pathogenicity of Neophysopella vitis Causing Rust Disease on Meliosma myriantha in Korea
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Dong Hwan Na, Jae Sung Lee, Young-Joon Choi, Ji-Hyun Park, and Hyeon-Dong Shin
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boston ivy ,morphology ,sequence analysis ,virginia creeper ,Agriculture (General) ,S1-972 - Abstract
Rust symptoms on Meliosma myriantha trees have been noticed during disease surveys in Korea since 2010, with a high disease incidence frequently surpassing 90%. The causal fungus of the rust disease was identified as Neophysopella vitis based on the morphological investigation and molecular sequence analysis of the internal transcribed spacer (ITS) and large subunit (LSU) rDNA regions. This is the first report of rust disease caused by N. vitis on M. myriantha in Korea. A pathogenicity assay proved that M. myriantha serves as the aecial host of N. vitis as spermogonia and aeciospores were produced, which can infect the two uredinial hosts, Boston ivy (Parthenocissus tricuspidata) and Virginia creeper (Parthenocissus quinquefolia).
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- 2023
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11. Unraveling the Life Cycle of Nyssopsora cedrelae: A Study of Rust Diseases on Aralia elata and Toona sinensis
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Jae Sung Lee, Makoto Kakishima, Ji-Hyun Park, Hyeon-Dong Shin, and Young-Joon Choi
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alternate host ,Korean angelica tree ,Pucciniales ,Puccinia caricis-araliae ,Biology (General) ,QH301-705.5 - Abstract
Rust disease poses a major threat to global agriculture and forestry. It is caused by types of Pucciniales, which often require alternate hosts for their life cycles. Nyssopsora cedrelae was previously identified as a rust pathogen on Toona sinensis in East and Southeast Asia. Although this species had been reported to be autoecious, completing its life cycle solely on T. sinensis, we hypothesized that it has a heteroecious life cycle, requiring an alternate host, since the spermogonial and aecial stages on Aralia elata, a plant native to East Asia, are frequently observed around the same area where N. cedrelae causes rust disease on T. sinensis. Upon collecting rust samples from both A. elata and T. sinensis, we confirmed that the rust species from both tree species exhibited matching internal transcribed spacer (ITS), large subunit (LSU) rDNA, and cytochrome oxidase subunit III (CO3) mtDNA sequences. Through cross-inoculations, we verified that aeciospores from A. elata produced a uredinial stage on T. sinensis. This study is the first report to clarify A. elata as an alternate host for N. cedrelae, thus providing initial evidence that the Nyssopsora species exhibits a heteroecious life cycle.
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- 2024
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12. Uncharted Diversity and Ecology of Saprolegniaceae (Oomycota) in Freshwater Environments
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Bora Nam, Thuong T. T. Nguyen, Hyang Burm Lee, Sang Kyu Park, and Young-Joon Choi
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Freshwater ecosystem ,Geolegnia ,Leptolegnia ,Saprolegnia ,seasonality ,substrate preference ,Botany ,QK1-989 - Abstract
AbstractThe fungal-like family Saprolegniaceae (Oomycota), also called “water mold,” includes mostly aquatic saprophytes as well as notorious aquatic animal pathogens. Most studies on Saprolegniaceae have been biased toward pathogenic species that are important to aquaculture rather than saprotrophic species, despite the latter’s crucial roles in carbon cycling of freshwater ecosystems. Few attempts have been made to study the diversity and ecology of Saprolegniaceae; thus, their ecological role is not well-known. During a survey of oomycetes between 2016 and 2021, we investigated the diversity and distribution of culturable Saprolegniaceae species in freshwater ecosystems of Korea. In the present study, members of Saprolegniaceae were isolated and identified at species level based on their cultural, morphological, and molecular phylogenetic analyses. Furthermore, substrate preference and seasonal dynamics for each were examined. Most of the species were previously reported as animal pathogens; however, in the present study, they were often isolated from other freshwater substrates, such as plant debris, algae, water, and soil sediment. The relative abundance of Saprolegniaceae was higher in the cold to cool season than that in the warm to hot season of Korea. This study enhances our understanding of the diversity and ecological attributes of Saprolegniaceae in freshwater ecosystems.
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- 2022
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13. Multiplex TaqMan qPCR Assay for Detection, Identification, and Quantification of Three Sclerotinia Species
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Dong Jae Lee, Jin A Lee, Dae-Han Chae, Hwi-Seo Jang, Young-Joon Choi, and Dalsoo Kim
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asp gene ,phylogeny ,TaqMan probe ,sclerotia ,white mold ,Botany ,QK1-989 - Abstract
AbstractWhite mold (or Sclerotinia stem rot), caused by Sclerotinia species, is a major air, soil, or seed-transmitted disease affecting numerous crops and wild plants. Microscopic or culture-based methods currently available for their detection and identification are time-consuming, laborious, and often erroneous. Therefore, we developed a multiplex quantitative PCR (qPCR) assay for the discrimination, detection, and quantification of DNA collected from each of the three economically relevant Sclerotinia species, namely, S. sclerotiorum, S. minor, and S. nivalis. TaqMan primer/probe combinations specific for each Sclerotinia species were designed based on the gene sequences encoding aspartyl protease. High specificity and sensitivity of each probe were confirmed for sclerotium and soil samples, as well as pure cultures, using simplex and multiplex qPCRs. This multiplex assay could be helpful in detecting and quantifying specific species of Sclerotinia, and therefore, may be valuable for disease diagnosis, forecasting, and management.
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- 2022
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14. Erysiphe quercicola Causing Powdery Mildew on Quercus rubra in Korea
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Young-Joon Choi, Jun Hyuk Park, In-Young Choi, Lamiya Abasova, Joon-Ho Choi, Dong-Hyeon Lee, and Chang Sun Kim
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emerging disease ,host expansion ,morphology ,phylogeny ,Biology (General) ,QH301-705.5 - Abstract
In Korea, powdery mildew has been observed on Quercus rubra, commonly called the northern red oak tree. Based on its morphological and molecular phylogenetic analyses, the fungal agent was identified as Erysiphe quercicola, but it was distinct from the other four Erysiphe species, specialized to Quercus species. This is the first confirmed report on the identity of powdery mildew found on Q. rubra in Korea. This finding can help understand the host expansion of E. quercicola and the biodiversity of powdery mildew on Quercus species.
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- 2022
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15. Three Unreported Fungi Isolated From Reservoirs in Korea: Mortierella biramosa, Paraphoma radicina, and Sordaria macrospora
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Bora Nam, Hyang Burm Lee, and Young-Joon Choi
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cultivation ,freshwater ,fungi ,morphology ,phylogeny ,Biology (General) ,QH301-705.5 - Abstract
Freshwater ecosystems have a large reserve of latent biological resources that play an essential ecological role, and have significant economic and social value. Fungi in freshwater are prospective materials that can be used in the food, medicine, and biomass energy fields. In this study, three promising fungal species were isolated from freshwater ecosystems in Korea. These isolates were identified as Mortierella biramosa, Paraphoma radicina, and Sordaria macrospora, based on their cultural and morphological characteristics, as well as molecular phylogenetic analyses. These species were previously unknown in Korea. The finding allows us to explore its physiological and biochemical characteristics in more detail and use them as biological resources.
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- 2022
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16. Emergence of a New Rust Disease of Virginia Creeper (Parthenocissus quinquefolia) through a Host Range Expansion of Neophysopella vitis
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Dong-Hwan Na, Jae Sung Lee, Hyeon-Dong Shin, Yoshitaka Ono, and Young-Joon Choi
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Boston Ivy ,host-jump ,obligate biotroph ,Pucciniales ,Vitaceae ,Botany ,QK1-989 - Abstract
Virginia creeper (or five-leaved ivy; Parthenocissus quinquefolia) is one of the most popular and widely grown climbers worldwide. In September 2021, Virginia creeper leaves with typical rust symptom were found in an arboretum in Korea, with severe damage. Globally, there is no record of a rust disease on Virginia creeper. Using morphological investigation and molecular phylogenetic inferences, the rust agent was identified as Neophysopella vitis, which is a rust pathogen of other Parthenocissus spp. including Boston ivy (P. tricuspidata). Given that the two ivy plants, Virginia creeper and Boston ivy, have common habitats, especially on buildings and walls, throughout Korea, and that N. vitis is a ubiquitous rust species affecting Boston ivy in Korea, it is speculated that the host range of N. vitis may recently have expanded from Boston ivy to Virginia creeper. The present study reports a globally new rust disease on Virginia creeper, which could be a major threat to the ornamental creeper.
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- 2022
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17. Taxonomy, Phylogeny, and Life Cycle of Four Neophysopella Species on Meliosma myriantha and M. oldhamii in Korea
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Dong Hwan Na, Jae Sung Lee, Hyeon-Dong Shin, and Young-Joon Choi
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cox3 ,Neophysopella meliosmae ,Neophysopella meliosmae-myrianthae ,Neophysopella vitis ,Pucciniales ,Plant ecology ,QK900-989 - Abstract
The present study performed an in-depth investigation of rust diseases affecting Meliosma myriantha and Meliosma oldhamii trees (Sabiaceae) in Korea. The analysis identified four distinct species of the genus Neophysopella (Pucciniales) as the causal agents. Among these, N. hornotina was found to infect only M. oldhamii, whereas three Neophysopella species (N. meliosmae, N. meliosmae-myrianthae, and N. vitis) were parasitic on M. myriantha. To our knowledge, this is the first report of the former two species (N. hornotina and N. meliosmae) in Korea. In addition, we specified their alternate host plants for two heteroecious species (N. meliosmae-myrianthae and N. vitis) in Korea, completing the life cycles of the four rust species, and provided detailed morphological descriptions at each stage of their life cycles. Phylogenetic relationships of these rust species were uncovered using a comprehensive sample size, and we have constructed a phylogenetic tree for Neophysopella using the cytochrome c oxidase subunit III (cox3) gene sequences, demonstrating an effective approach for species delineation within this genus. The findings contribute to identifying and managing rust diseases affecting Meliosma species.
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- 2023
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18. Identification of Pseudocercospora bolleana Associated with Angular Leaf Spot on Common Fig in Korea
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In-Young Choi, Young-Joon Choi, Chong-Kyu Lee, and Hyeon-Dong Shin
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cercosporoid fungus ,ficus carica ,passalora bolleana ,pseudocercospora fici-caricae ,Biology (General) ,QH301-705.5 - Abstract
A cercosporoid fungus associated with angular leaf spots on the leaves of common fig (Ficus carica) in Korea is known to be morphologically similar to Passalora, but phylogenetically similar to Pseudocercospora. To clarify the ambiguity, six fig samples with angular leaf spots were collected and examined using a microscope, and two representative isolates were sequenced for multiple genes. The morphological characteristics were consistent with previous descriptions of Passalora bolleana. Molecular phylogenetic analysis based on the internal transcribed spacer and large subunit ribosomal DNA (rDNA) regions showed that the Korean isolates, as well as previously published Korean and Romanian isolates, formed a well-supported group in the clade of Pseudocercospora species. Consequently, the current Korean isolates should be correctly described as Pseudocercospora bolleana. Additionally, Pseudocercospora fici-caricae, a cercosporoid fungus previously described as a leaf pathogen on common fig in Taiwan and Korea, was also compared and discussed.
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- 2021
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19. Rust Fungus Pucciniastrum styracinum on Styrax japonicus in Korea Confirmed by Morphological and Molecular Data
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Ji-Hyun Park, Bok-Nam Jung, Jae Sung Lee, Young-Joon Choi, and Hyeon-Dong Shin
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molecular analysis ,morphology ,styrax obassia ,uredinales ,Biology (General) ,QH301-705.5 - Abstract
Styrax japonicus is a deciduous shrub or a small tree belonging to the family Styracaceae. Since 1990, a rust fungus has continuously been found on S. japonicus leaves across the country. The morphological characteristics of the rust fungus were most consistent with those of Pucciniastrum styracinum reported on Styrax obassia in Japan. The species identification was confirmed by molecular phylogenetic analysis of the internal transcribed spacer and large subunit rDNA sequences. The current study provides mycological information with morphological measurements and molecular phylogenetic data of P. styracinum found on S. japonicus in Korea. Therefore, this is the first confirmed report on the presence of P. styracinum on S. japonicus in Korea.
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- 2021
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20. High-Temperature-Tolerant Fungus and Oomycetes in Korea, Including Saksenaea longicolla sp. nov.
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Bora Nam, Dong-Jae Lee, and Young-Joon Choi
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climate change ,freshwater ,microbial diversity ,mucorales ,oomycota ,Botany ,QK1-989 - Abstract
Global temperatures are steadily increasing, leading to significant changes in microbial diversity and ecology. In the present study, we isolated high-temperature-growing fungi and fungi-like group (Oomycota) strains from freshwater environments of Korea and identified them based on cultural, morphological, and multilocus phylogenetic analyses. As a result, we introduce Saksenaea (Fungi) isolates as a new species, Saksenaea longicolla sp. nov. and record Phytophthora chlamydospora and P. lagoariana (Oomycota) new to Korea. In the growth experiments, they exhibited high-temperature tolerance, which can grow at 35–40 °C but become inactive at 4 °C and below. This study confirms the presence of high-temperature-tolerant fungi and oomycetes in Korea and suggests that the Korean climate conditions are changing in favor of these species. This indicates that climate warming is altering microbial distributions in freshwater environments.
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- 2021
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21. Bremia lactucae causing Downy Mildew on Lactuca serriola in Korea
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Jin A Lee, Bora Kim, Dong-Jae Lee, and Young-Joon Choi
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invasive weed, lactuca scariola, lettuce, oomycota ,Biology (General) ,QH301-705.5 - Abstract
Lactuca serriola L. (syn. L. scariola L.), commonly known as prickly lettuce, invaded Korea in the late 1970s. The plant has since become widely naturalized and disruptive to native plant communities. In May 2020, downy mildew infections were observed on L. serriola in Gimje-si, Korea. Molecular phylogenetic and morphological analyses identified the causal agent as Bremia lactucae. This is the first report of B. lactucae infection on L. serriola in Korea.
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- 2021
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22. Organic Farming Allows Balanced Fungal and Oomycetes Communities
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Bora Nam, Hyo Jung Lee, and Young-Joon Choi
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organic farming ,fungi ,oomycetes ,Biology (General) ,QH301-705.5 - Abstract
Conventional and organic farming systems affect soils differently, thereby influencing microbial diversity and composition. Organic farming, which relies on natural processes, biodiversity, and cycles adapted to local conditions, is generally known to improve soil texture and alleviate microbial diversity loss compared with that of conventional farming, which uses synthetic inputs such as chemical fertilisers, pesticides, and herbicides. Although they affect the health and productivity of host plants, the community dynamics of fungi and fungi-like oomycetes (under Chromista) in organic farmland are poorly understood. The present study aimed to determine the differences in the diversity and composition of fungi and oomycetes inhabiting organic and conventional farm soils using culture-based DNA barcoding and culture-independent environmental DNA (eDNA) metabarcoding. Four tomato farms with different farming practices were selected and investigated: mature pure organic (MPO) via non-pesticide and organic fertiliser, mature integrated organic (MIO) via non-pesticide and chemical fertiliser, mature conventional chemical (MCC) via both pesticide and chemical fertiliser, and young conventional chemical (YCC). Culture-based analysis revealed that different genera were dominant on the four farms: Linnemannia in MPO, Mucor in MIO, and Globisporangium in MCC and YCC. eDNA metabarcoding demonstrated that the fungal richness and diversity on the MPO farm were higher than that on other farms. Both conventional farms exhibited simpler fungal and oomycete network structures with lower phylogenetic diversity. Interestingly, a high richness of oomycetes was shown in YCC; in which, Globisporangium, a potential pathogenic group on tomato plants, was abundantly observed. Our findings indicate that organic farming enhances fungal and oomycete diversity, which may provide robust support for maintaining healthy and sustainable agricultural practices. This study contributes to our knowledge on the positive effects of organic farming on crop microbiomes and provides essential information for maintaining biological diversity.
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- 2023
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23. Puccinia klugkistiana, a Rust Fungus Occurring on Cleistogenes hackelii in Korea
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Jae-Sung Lee, Young-Joon Choi, In-Young Choi, Chong-Kyu Lee, and Hyeon-Dong Shin
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aecidium klugkistianum ,ligustrum ,puccinia diplachnicola ,teliospore ,urediniospore ,Biology (General) ,QH301-705.5 - Abstract
Rust samples at both uredinial and telial stages were collected from Cleistogenes hackelii (Poaceae) in 2017 and 2019 in Korea. Based on the morphological examination and molecular phylogenetic analyses of the internal transcribed spacer (ITS) and large subunit (LSU) rDNA, it was identified as Puccinia klugkistiana. This rust at aecial stage has previously been recorded on Ligustrum japonicum (Oleaceae) in Korea. Puccinia diplachnicola has been previously recorded on C. hackelii in Korea; however, it is believed to be unrelated to the rust collected in the present study. Conclusively, this is the first study to report P. klugkistiana occurrence on C. hackelii in Korea.
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- 2021
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24. Co-Occurrence of Two Phylogenetic Clades of Pseudoperonospora cubensis, the Causal Agent of Downy Mildew Disease, on Oriental Pickling Melon
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Dong Jae Lee, Jae Sung Lee, and Young-Joon Choi
- Subjects
cox2 mtdna ,downy mildew ,phylogenetic analysis ,pseudoperonospora humuli ,Botany ,QK1-989 - Abstract
The genus Pseudoperonospora, an obligate biotrophic group of Oomycota, causes the most destructive foliar downy mildew disease on many economically important crops and wild plants. A previously unreported disease by Pseudoperonospora was found on oriental pickling melon (Cucumis melo var. conomon) in Korea, which is a minor crop cultivated in the temperate climate zone of East Asia, including China, Korea, and Japan. Based on molecular phylogenetic and morphological analyses, the causal agent was identified as Pseudoperonospora cubensis, and its pathogenicity has been proven. Importantly, two phylogenetic clades of P. cubensis, harboring probably two distinct species, were detected within the same plots, suggesting simultaneous coexistence of the two clades. This is the first report of P. cubensis causing downy mildew on oriental pickling melon in Korea, and the confirmation of presence of two phylogenetic clades of this pathogen in Korea. Given the high incidence of P. cubensis and high susceptibility of oriental pickling melon to this disease, phytosanitary measures, including rapid diagnosis and effective control management, are urgently required.
- Published
- 2021
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25. Pucciniastrum hydrangeae-petiolaris, a Newly Found Rust Fungus on Hydrangea petiolaris in Korea
- Author
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Jae Sung Lee, Young-Joon Choi, Byoung-Ki Choi, Bok-Nam Jung, Ji-Hyun Park, and Hyeon-Dong Shin
- Subjects
identification ,phylogeny ,pucciniastraceae ,pucciniastrum hydrangeae ,sem ,Biology (General) ,QH301-705.5 - Published
- 2021
- Full Text
- View/download PDF
26. Macruropyxis fraxini on Fraxinus rhynchophylla: Confirmation in the Korean Peninsula after 82 Years and the First Record in South Korea
- Author
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Bok-Nam Jung, Young-Joon Choi, Hyeon-Dong Shin, and Ji-Hyun Park
- Subjects
fraxinus ,identification ,phylogeny ,puccinia fraxini ,uropyxis fraxini ,Botany ,QK1-989 - Abstract
Macruropyxis fraxini has been recorded on several species of Fraxinus in China, Japan, Russia (Far East), and North Korea since its first recorded observation as a rust fungus on F. rhynchophylla in Jilin, China, in 1899. In the Korean Peninsula, the rust fungus was first recorded on F. rhynchophylla in 1935, based on four specimens collected at Mt. Kumgangsan, Gangwondo Province, in the North Korean territory. We confirmed this rust in the Korean Peninsula after 82 years. The rust fungus was identified based on morphological characteristics and a molecular phylogenetic analysis. This is the first record of M. fraxini in South Korea.
- Published
- 2020
- Full Text
- View/download PDF
27. Results of total knee arthroplasty for painless, stiff knees
- Author
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Young-Joon Choi, Dong-Kyo Seo, Ki Won Lee, Ho Jong Ra, Hyun Wook Kang, and Jin Kyung Kim
- Subjects
Knee ,Stiff ,Ankylosis ,Total knee arthroplasty ,Orthopedic surgery ,RD701-811 - Abstract
Abstract Background Stiff knees, like completely ankylosed or arthrodesed knees, can be painless. Total knee arthroplasty (TKA) for these painless, stiff knees is technically demanding. However, it can correct the alignment and advance the range of motion to improve quality of life. So, we reviewed the preoperative and postoperative results of functional and pain scores, range of motion (ROM) and complications in painless, stiff knees treated by TKA. Methods Fifteen painless, stiff knees underwent TKA from January 1998 to January 2017. The mean follow-up period was 15.4 (2.4–22.2) years. All the knees were completely ankylosed or arthrodesed. Clinical outcome and complications were evaluated using medical record review, serial plan radiography, ROM assessment, Knee Society score (KSS), Knee Society function score (FS), and a visual analog scale for pain (VAS). Results All patients were satisfied with their operated knees. Mean KSS and FS scores were improved from 36 and 50.9 to 76.9 and 67.2, respectively (P
- Published
- 2020
- Full Text
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28. Identification of Sphaerulina azaleae on Korean Azalea in Korea Based on Morphological Characteristics and Multilocus Sequence Typing
- Author
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In-Young Choi, Young-Joon Choi, Kui-Jae Lee, Ho-Jong Ju, Seong-Wan Cho, and Hyeon-Dong Shin
- Subjects
angular leaf spot ,korean azalea ,rhododendron yedoense f. poukhanense ,sphaerulina azaleae ,Biology (General) ,QH301-705.5 - Abstract
From 2008 to 2017, Korean azalea (Rhododendron yedoense f. poukhanense) showing angular, necrotic leaf spots were found in Jeju and Hongcheon, Korea. The lesions occurred frequently, detracting from the beauty of the glossy green leaves of the plant and causing premature defoliation. Therefore, to identify the fungus associated with the lesions, morphological characterization and molecular phylogenetic analysis of actin (Act), translation elongation factor 1-alpha (EF), internal transcribed spacer (ITS), 28S nrDNA (LSU), and RNA polymerase II encoding the second largest subunit (RPB2) of the two representative isolates were performed. The phylogenetic tree inferred from the neighbor-joining method showed the isolates clustering in the Sphaerulina azaleae group. Therefore, the fungus associated with the angular leaf spots on the Korean azalea was identified as Sphaerulina azaleae.
- Published
- 2020
- Full Text
- View/download PDF
29. One Hundred Representative Fungi in Korea and Their Korean Names
- Author
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Hyo-Won Choi, Young Woon Lim, Myoung-Dong Kim, Jayoung Kim, Changmu KIM, Chang Sun Kim, Yun-Su Do, Chang-Gi Back, Hyunkyu Sang, Woo Chang Shin, Seung-Yeol Lee, Dawoon Chung, Hee-Young Jung, Young-Joon Choi, In-Young Choi, Jae-Gu Han, and Seung-Beom Hong
- Subjects
korean names of fungi ,mold ,mushroom ,plant pathogenic fungi ,representative fungi ,Biology (General) ,QH301-705.5 - Abstract
One hundred representative species of fungi in Korea were selected and their Korean names were proposed to increase interest in fungi among Korean people. This task was performed under the supervision of the Committee of Mycological Terms, under the Korean Society of Mycology. First, the committee established the criteria for selecting 100 representative species of fungi in Korea and then selected the candidate fungal species accordingly. To ensure the uniformity and stability of Korean fungal names, the principle of naming fungi in Korean was established, and the candidate Korean fungal names were presented accordingly. Finally, the candidate Korean fungal names were posted online to collect opinions of the members of the Korean Society of Mycology. The candidate Korean names of the plant pathogenic fungi and mushrooms were reviewed by the Korean Society of Plant Pathology and the Korean Society of Mushroom Science, respectively. After their opinions were considered, the Korean names for 100 representative fungi in Korea were finally determined. The 100 fungi comprised 41 common molds and yeasts, 28 plant pathogenic fungi, and 31 mushrooms.
- Published
- 2020
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30. Rediscovery of Seven Long-Forgotten Species of Peronospora and Plasmopara (Oomycota)
- Author
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Jae Sung Lee, Hyeon-Dong Shin, and Young-Joon Choi
- Subjects
barcoding ,downy mildew ,morphology ,peronosporaceae ,phylogenetic analysis ,Botany ,QK1-989 - Abstract
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.
- Published
- 2020
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31. Plasmopara elegantissima sp. nov. (Oomycota, Peronosporales), a Downy Mildew Species Specialized to Impatiens textori (Balsaminaceae)
- Author
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Young-Joon Choi, Marlena Görg, Hyeon-Dong Shin, and Marco Thines
- Subjects
cox2 mtdna ,multi-locus phylogeny ,peronosporaceae ,taxonomy ,allopatric speciation ,Botany ,QK1-989 - Abstract
Over the past 15 years, downy mildew became the most destructive foliar disease in cultivated Impatiens species (Balsaminaceae) worldwide. A previous study had revealed that the causal agent was not Plasmopara obducens (Oomycota, Peronosporales) but Plasmopara destructor on Impatiens walleriana, and Plasmopara velutina on Impatiens balsamina. This hints to a relatively high degree of specialization of Plasmopara on Balsaminaceae. Therefore, it was the aim of the present study to perform multigene phylogenetic analysis and detailed morphological investigation for several Korean downy mildew samples parasitic to cultivated I. walleriana, and I. balsamina, but also to a northeast Asian wild plant, Impatiens textori. It was revealed that I. textori harbors a new species, which is introduced and described here as Plasmopara elegantissima.
- Published
- 2020
- Full Text
- View/download PDF
32. Pezizomycotina (Ascomycota) Fungi Isolated from Freshwater Environments of Korea: Cladorrhinum australe, Curvularia muehlenbeckiae, Curvularia pseudobrachyspora , and Diaporthe longicolla
- Author
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Bora Nam, Jae Sung Lee, Hyang Burm Lee, and Young-Joon Choi
- Subjects
diversity ,dothideomycetes ,freshwater ,its rdna ,sordariomycetes ,Biology (General) ,QH301-705.5 - Abstract
Fungi are ubiquitous and indispensable components of nearly all ecosystems on earth, including freshwater environments. A survey of fungal diversity in freshwater environments of Korea led to the identification of four unrecorded Pezizomycotina (Ascomycota) species in 2016 and 2017, based on morphology and molecular phylogeny; these included Cladorrhinum australe, Curvularia muehlenbeckiae, Curvularia pseudobrachyspora (Dothideomycetes), and Diaporthe longicolla (Sordariomycetes).
- Published
- 2020
- Full Text
- View/download PDF
33. First Report of Peach Fruit Rot Caused by Fusarium avenaceum in Korea
- Author
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A Yeong Heo, Young Mo Koo, Young-Joon Choi, Sang Hee Kim, Gyu Young Chung, and Hyong Woo Choi
- Subjects
fruit rot ,fusarium avenaceum ,peach fruits ,Agriculture (General) ,S1-972 - Abstract
In July 2019, typical rot symptom was observed on peach fruits harvested from the fields at Andong, Korea. As the disease progressed, white and purple colored mycelial mat developed on the surface of the infected fruits. A causal pathogen was isolated from the infected fruit and cultured on potato dextrose agar media for identification. Fungal colonies on potato dextrose agar produced 3 pigments, including purple, yellow, and white colors. The isolate incited fruit rot symptoms on artificially inoculated peach fruits, from which the same fungus was isolated, fulfilling Koch’s postulates. Based on the morphological characteristics and sequence analysis of rDNA internal transcribed spacer, translation elongation factor 1-alpha, and β-tubulin, the causal agent of the disease was identified as Fusarium avenaceum. This study is the first report of fruit rot of peach fruits caused by Fusarium avenaceum in Korea.
- Published
- 2020
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- View/download PDF
34. Four Endophytic Ascomycetes New to Korea: Cladosporium anthropophilum, C. pseudocladosporioides, Daldinia eschscholtzii, and Nigrospora chinensis
- Author
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Dong Jae Lee, Jae Sung Lee, Hyang Burm Lee, and Young-Joon Choi
- Subjects
ascomycota ,diversity ,endophyte ,its rdna ,tef1 ,Biology (General) ,QH301-705.5 - Abstract
Ascomycota is the largest phylum of the Fungi, including approximately 6,600 genera. They are often isolated from soils, indoor air, and freshwater environments, but also from plants as pathogens or endophytes. In this study, four species of Ascomycota (two of Cladosporium and one of each Daldinia and Nigrospora) were collected from the leaves of four woody plants (Camellia japonica, Ginkgo biloba, Quercus sp., Vitis vinifera). Their cultural characteristics were investigated on five different media (PDA, V8A, CMA, MEA, CZA) at 3 days after incubation at 25°C in darkness. BLASTn search and phylogenetic analysis were performed using the internal transcribed spacer (ITS) rDNA sequences, in addition to tef1 gene sequences for Cladosporium species. Based on the cultural, morphological, and phylogenetic data, the isolates were identified as Cladosporium anthropophilum, Cladosporium pseudocladosporioides, Daldinia eschscholtzii, and Nigrospora chinensis. Previously, some members of Cladosporium and Nigrospora have been recorded as endophytes inhabiting the leaves and stems of various plants, whereas Daldinia eschscholtzii is a wood-inhabiting endophyte or wood-decaying fungus. To our knowledge, this is the first report of these four ascomycetes in Korea.
- Published
- 2019
- Full Text
- View/download PDF
35. Grovesinia moricola occurring on Parthenocissus tricuspidata
- Author
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Hyeon-Dong Shin, Young-Joon Choi, Sun-Hee Hong, and Yong-Ho Lee
- Subjects
boston ivy ,cristulariella moricola ,grovesinia moricola ,internal transcribed spacer rdna ,Biology (General) ,QH301-705.5 - Abstract
Between August and September 2017, zonate leaf spots with severe defoliation were observed on Parthenocissus tricuspidata in Gimcheon, Korea. The initial symptoms included water-soaked, gray to grayish brown, circular or irregular-shaped leaf spots. As the disease progressed, the spots enlarged, coalesced, and became cream-colored with characteristic target-shaped rings, leading to leaf blight and premature defoliation. Based on cultural and morphological characteristics, the fungus associated with the symptoms was identified as Grovesinia moricola. The identity of this fungus was confirmed by analyzing sequences of the internal transcribed spacer region of ribosomal DNA. The pathogenicity of the isolate was demonstrated by artificial inoculation. To our knowledge, this is the first report of G. moricola occurring on P. tricuspidata globally as well as in Korea.
- Published
- 2019
- Full Text
- View/download PDF
36. Phytopythium and Pythium Species (Oomycota) Isolated from Freshwater Environments of Korea
- Author
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Bora Nam and Young-Joon Choi
- Subjects
Oomycete ,freshwater ,taxonomy ,ecology ,pythiales ,Botany ,QK1-989 - Abstract
Oomycetes are widely distributed in various environments, including desert and polar regions. Depending upon different habits and hosts, they have evolved with both saprophytic and pathogenic nutritional modes. Freshwater ecosystem is one of the most important habitats for members of oomycetes. Most studies on oomycete diversity, however, have been biased mostly towards terrestrial phytopathogenic species, rather than aquatic species, although their roles as saprophytes and parasites are essential for freshwater ecosystems. In this study, we isolated oomycete strains from soil sediment, algae, and decaying plant debris in freshwater streams of Korea. The strains were identified based on cultural and morphological characteristics, as well as molecular phylogenetic analyses of ITS rDNA, cox1, and cox2 mtDNA sequences. As a result, we discovered eight oomycete species previously unknown in Korea, namely Phytopythium chamaehyphon, Phytopythium litorale, Phytopythium vexans, Pythium diclinum, Pythium heterothallicum, Pythium inflatum, Pythium intermedium, and Pythium oopapillum. Diversity and ecology of freshwater oomycetes in Korea are poorly understood. This study could contribute to understand their distribution and ecological function in freshwater ecosystem.
- Published
- 2019
- Full Text
- View/download PDF
37. New Downy Mildew Disease Caused by Hyaloperonospora brassicae on Pak choi (Brassica rapa) in Korea
- Author
-
Hyun Ju Lee, Jae Sung Lee, and Young-Joon Choi
- Subjects
Brassica ,downy mildew ,Oomycota ,Pak choi ,Phylogeny ,Agriculture (General) ,S1-972 - Abstract
Pak choi (or a Bok choy; Brassica rapa subsp. chinensis) is a popular brassicaceous vegetable worldwide. In January 2019, a downy mildew symptom on pak choi was found at a farm located in Yongin, Korea. Based on morphological characteristics and molecular phylogenetic inference, the pathogenic oomycete was identified as Hyaloperonospora brassicae. To our knowledge, this is the first report of downy mildew disease occurring on pak choi in Korea. Considering the increasing demand for this crop, this pathogen would be a potentially new threat to the cultivation of pak choi in Korea.
- Published
- 2019
- Full Text
- View/download PDF
38. Characterization of Achlya americana and A. bisexualis (Saprolegniales, Oomycota) Isolated from Freshwater Environments in Korea
- Author
-
Young-Joon Choi, Seo Hee Lee, Thuong T. T. Nguyen, Bora Nam, and Hyang Burm Lee
- Subjects
Achlyaceae ,emerging disease ,freshwater fungi ,mycosis ,oomycetes ,Botany ,QK1-989 - Abstract
Many members of the Saprolegniales (Oomycete) cause mycoses and disorders of fishes, of which Achlya and Saprolegnia are most ubiquitous genera worldwide. During a survey of the diversity of freshwater oomycetes in Korea, we collected seven isolates of Achlya, for which morphological and molecular phylogenetic analyses enabled them to identify as Achlya americana and Achlya bisexualis. In Korea, only a species of Achlya, A. prolifera, has been previously found to cause seedling rot on rice (Oryza sativa), but none of the two species have been reported yet. Importantly, A. bisexualis was isolated from a live fish, namely rice fish (Oryzias sinensis), as well as freshwater, and this is the first report of Achlya-causing mycoses on freshwater fishes in Korea. The presence of A. americana and A. bisexualis on live fish in Korea should be closely monitored, as considering the well-known broad infectivity of these species it has the potential to cause an important emerging disease on aquaculture industry.
- Published
- 2019
- Full Text
- View/download PDF
39. Diversity of Aspergillus, Penicillium, and Talaromyces Species Isolated from Freshwater Environments in Korea
- Author
-
Inbeom Heo, Kyeongyeon Hong, Hyejin Yang, Hyang Burm Lee, Young-Joon Choi, and Seung-Beom Hong
- Subjects
Aspergillus ,Penicillium piscarium ,Talaromyces versatilis ,freshwater fungi ,Korea ,Botany ,QK1-989 - Abstract
In order to elucidate the fungal diversity and community structure in freshwater environments, numerous fungal strains were isolated from freshwater, submerged soils, twigs, dead insects, etc. Among them, the present study has focused specifically on Aspergillus, Penicillium, and Talaromyces species, which produce diverse useful metabolites in general. Twelve strains of Aspergillus isolated were identified as A. japonicus (n = 5), A. tubingensis (3), A. niger (2), and A. flavus (2), 10 strains of which belong to Aspergillus section Nigri, named black Aspergillus. Eight strains of Penicillium were identified as P. brasilianim (n = 3), P. oxalicum (2), P. crustosum (1), P. expansum (1), and P. piscarium (1). Two different strains of Talaromyces were identified as T. pinophilus and T. versatilis. Thus far, Penicillium piscarium and Talaromyces versatilis have been unrecorded in Korea, for which we provide detailed morphological and molecular characteristics.
- Published
- 2019
- Full Text
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40. Bremia itoana (Oomycota, Peronosporales), a Specialized Downy Mildew Pathogen on an East Asian Plant, Crepidiastrum sonchifolium (Asteraceae)
- Author
-
Young-Joon Choi, Ji Hoon Park, Jeongran Lee, and Hyeon-Dong Shin
- Subjects
Barcoding ,Cichorioideae ,cox2 mtDNA ,downy mildew ,newly emerging disease ,Botany ,QK1-989 - Abstract
Crepidiastrum sonchifolium, a flowering plant in the daisy family (Asteraceae), is native to East Asia. In Korea, this plant is a locally cultivated vegetable, and its market size is gradually growing. Since the plants with downy mildew infection were initially found at a private farm of Chuncheon city, the occurrences have continued in commercial farms of other regions, highlighting that this disease is spreading throughout Korea. The pathogen was attributed to a member of the genus Bremia that contains many specialized species, each of which displays a narrow host spectrum on Asteraceae. Based on morphological and molecular phylogenetic analyses, along with the high host specificity recently proven for Bremia species, the identity of the causal agent was confirmed as a so far undescribed species of Bremia. Here, we introduce Bremia itoana sp. nov., specific to C. sonchifolium.
- Published
- 2018
- Full Text
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41. Host Jumps and Radiation, Not Co-Divergence Drives Diversification of Obligate Pathogens. A Case Study in Downy Mildews and Asteraceae.
- Author
-
Young-Joon Choi and Marco Thines
- Subjects
Medicine ,Science - Abstract
Even though the microevolution of plant hosts and pathogens has been intensely studied, knowledge regarding macro-evolutionary patterns is limited. Having the highest species diversity and host-specificity among Oomycetes, downy mildews are a useful a model for investigating long-term host-pathogen coevolution. We show that phylogenies of Bremia and Asteraceae are significantly congruent. The accepted hypothesis is that pathogens have diverged contemporarily with their hosts. But maximum clade age estimation and sequence divergence comparison reveal that congruence is not due to long-term coevolution but rather due to host-shift driven speciation (pseudo-cospeciation). This pattern results from parasite radiation in related hosts, long after radiation and speciation of the hosts. As large host shifts free pathogens from hosts with effector triggered immunity subsequent radiation and diversification in related hosts with similar innate immunity may follow, resulting in a pattern mimicking true co-divergence, which is probably limited to the terminal nodes in many pathogen groups.
- Published
- 2015
- Full Text
- View/download PDF
42. Regulation of c-SMAC formation and AKT-mTOR signaling by the TSG101-IFT20 axis in CD4+ T cells
- Author
-
Jiung Jeong, In Kang, Yumin Kim, Keun Bon Ku, Jang Hyun Park, Hyun-Jin Kim, Chae Won Kim, Jeongwoo La, Hi Eun Jung, Hyeon Cheol Kim, Young Joon Choi, Jaeho Kim, Joon Kim, and Heung Kyu Lee
- Subjects
Infectious Diseases ,Immunology ,Immunology and Allergy - Abstract
CD4+ T cells play major roles in the adaptive immune system, which requires antigen recognition, costimulation, and cytokines for its elaborate orchestration. Recent studies have provided new insight into the importance of the supramolecular activation cluster (SMAC), which comprises concentric circles and is involved in the amplification of CD4+ T cell activation. However, the underlying mechanism of SMAC formation remains poorly understood. Here, we performed single-cell RNA sequencing of CD4+ T cells left unstimulated and stimulated with anti-CD3 and anti-CD28 antibodies to identify novel proteins involved in their regulation. We found that intraflagellar transport 20 (IFT20), previously known as cilia-forming protein, was upregulated in antibody-stimulated CD4+ T cells compared to unstimulated CD4+ T cells. We also found that IFT20 interacted with tumor susceptibility gene 101 (TSG101), a protein that endocytoses ubiquitinated T-cell receptors. The interaction between IFT20 and TSG101 promoted SMAC formation, which led to amplification of AKT-mTOR signaling. However, IFT20-deficient CD4+ T cells showed SMAC malformation, resulting in reduced CD4+ T cell proliferation, aerobic glycolysis, and cellular respiration. Finally, mice with T-cell-specific IFT20 deficiency exhibited reduced allergen-induced airway inflammation. Thus, our data suggest that the IFT20-TSG101 axis regulates AKT-mTOR signaling via SMAC formation.
- Published
- 2023
43. A Study on MICE Visitor Experience and Satisfaction During the COVID-19 Pandemic
- Author
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Jun-Hee Yoon, Ji-Yon Lee, and Young-Joon Choi
- Published
- 2023
44. The Effect of the Career Identity of Unemployed Young People on Employment Behavior
- Author
-
Young-Joon Choi
- Published
- 2022
45. Effects of Climacteric Women’s Forest Healing Participation Motivation and Interpersonal Relationships on Psychological Stability
- Author
-
Young-Joon Choi
- Published
- 2022
46. An Analysis of Effects on Job Search of the Middle age’s: Based on the Positive Psychological Capital
- Author
-
Young-Joon Choi
- Published
- 2022
47. A Qualitative Study on the Development of Digital Platform for Exhibitions
- Author
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Young-Joon Choi, Da-Hye Kim, and Hwa-Bong Lee
- Published
- 2022
48. CD5 Suppresses IL-15–Induced Proliferation of Human Memory CD8+ T Cells by Inhibiting mTOR Pathways
- Author
-
Eui-Cheol Shin, Young Joon Choi, Moa Sa, Su-Hyung Park, So Young Kim, June-Young Koh, Ho-Young Lee, and Jong Hoon Kim
- Subjects
biology ,Chemistry ,Immunology ,Human memory ,Cell biology ,immune system diseases ,Interleukin 15 ,hemic and lymphatic diseases ,biology.protein ,Cytotoxic T cell ,Immunology and Allergy ,CD5 ,Antibody ,PI3K/AKT/mTOR pathway ,CD8 - Abstract
IL-15 induces the proliferation of memory CD8+ T cells as well as NK cells. The expression of CD5 inversely correlates with the IL-15 responsiveness of human memory CD8+ T cells. However, whether CD5 directly regulates IL-15–induced proliferation of human memory CD8+ T cells is unknown. In the current study, we demonstrate that human memory CD8+ T cells in advanced stages of differentiation respond to IL-15 better than human memory CD8+ T cells in stages of less differentiation. We also found that the expression level of CD5 is the best correlate for IL-15 hyporesponsiveness among human memory CD8+ T cells. Importantly, we found that IL-15–induced proliferation of human memory CD8+ T cells is significantly enhanced by blocking CD5 with Abs or knocking down CD5 expression using small interfering RNA, indicating that CD5 directly suppresses the IL-15–induced proliferation of human memory CD8+ T cells. We also found that CD5 inhibits activation of the mTOR pathway, which is required for IL-15–induced proliferation of human memory CD8+ T cells. Taken together, the results indicate that CD5 is not just a correlative marker for IL-15 hyporesponsiveness, but it also directly suppresses IL-15–induced proliferation of human memory CD8+ T cells by inhibiting mTOR pathways.
- Published
- 2022
49. A Study on the Prevention and Treatment of Infectious Diseases in Mongolian Traditional Medical Education Institutions : Focusing on Smallpox in the 17th to 20th Centuries
- Author
-
Kyongna Kim and Young-Joon Choi
- Subjects
General Medicine - Published
- 2022
50. First Report of Powdery Mildew Caused by Golovinomyces ambrosiae on Erigeron annuus in Korea
- Author
-
Jun Hyuk, Park, Young-Joon, Choi, In-Young, Choi, and Hyeon-Dong, Shin
- Subjects
Plant Science ,Agronomy and Crop Science - Abstract
Erigeron annuus (L.) Pers., known as annual fleabane or eastern daisy fleabane, is native to North America and was unintentionally introduced to Korea in the 1910s (Park, 1995). It is now widely naturalized throughout Korea and was designated as one of the ten major introduced plants in Korea by the Korea National Arboretum. In September 2012, several dozen annual fleabanes were found to be heavily infected with powdery mildew. Symptoms first appeared as circular to irregular white patches, which subsequently showed abundant hyphal growth on both sides of the leaves. The same symptoms have continuously been found on annual fleabane throughout the country, where the disease incidence was often higher than 80%. Five voucher specimens were deposited in the Korea University Herbarium (KUS-F30208, 31414, 31774, 31784 and 32003). Hyphae were septate, branched, and 4.5 to 6.7 µm wide. Appressoria on the mycelium were lobed. Conidiophores (n = 30), measured 154 to 215 × 9 to 12.5 μm, were simple and produced 2 to 4 immature conidia in chains with a sinuate outline, followed by 2 to 3 cells. Foot-cells of conidiophores were straight, cylindrical, and 40 to 98 µm long. Conidia (n = 30) were hyaline, ellipsoid to barrel-shaped, measured 25.3 to 35.8 × 13 to 17 μm (length/width ratio = 1.62 to 2.31), lacked distinct fibrosin bodies, and showed reticulate wrinkling of the outer walls. Primary conidia were apically rounded and basally truncated and generally smaller than the secondary conidia. Germ tubes were produced on the subterminal position of conidia. No chasmothecia were observed. The structures described above were typical of the Euoidium anamorph of the genus Golovinomyces, and the fungus measurements were compatible with those of G. ambrosiae (Schwein.) U. Braun & R.T.A. Cook (Qiu et al., 2020). To confirm the identity of the causal fungus, the internal transcribed spacer (ITS) and large subunit (LSU) regions of rDNA from the five herbarium specimens were amplified with primers PM10/ITS4 for ITS and PM3/TW14 for LSU (Bradshaw and Tobin, 2020; Mori et al., 2000; White et al., 1990) and sequenced directly. The resulting sequence was deposited in GenBank (Accession No. OP788040-4 for ITS and OP788045-9 for LSU). Comparison with the sequences available in the GenBank database revealed that the isolates showed 100% sequence similarity with those of G. ambrosiae from the family Asteraceae (e.g., MT355557, MF612182, etc.). Pathogenicity was confirmed through inoculation by gently pressing diseased leaves onto the leaves of five healthy potted plants. Five non-inoculated plants served as controls. Plants were maintained in a greenhouse at 22 to 28°C. Inoculated plants developed signs and symptoms after seven days, whereas the control plants remained healthy. The fungus present on the inoculated plants was morphologically identical to that observed initially on diseased plants, fulfilling Koch’s postulates. Powdery mildew infections of Erigeron spp. associated with Golovinomyces species have been known in the United States, France, and China (Farr and Rossman, 2022). To our knowledge, this is the first report of powdery mildew disease caused by G. ambrosiae on E. annuus outside of North America as well as in Korea. According to our field observation, powdery mildew infections were found only on annual fleabanes growing in shady areas, not in sunny places.
- Published
- 2022
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