• The Korean Journal of Mycology
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• v.48 no.4
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• pp.397-405
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• 2020

Beech mushroom (Hypsizygus marmoreus) is one of the most popular mushrooms in Japan, China, and Korea because of its delicious taste, nutritious value, and unique crunchy texture. In 2018-2019, unusual signs on the mushroom were observed in mushroom farms in Gyeongnam Province. The main signs were the inhibition of mycelial growth and primordial formation on the surface of mushroom media. When green mold caused contamination at early stage, the rate of pinhead formation by the mushroom greatly decreased to 46.5-71.5%. Conidia of the causal green mold were ellipsoidal, dark green, and measured 2.0-3.1㎛ long. The optimum temperature for mycelial growth of the green mold was 25℃. The phylogenetic tree obtained from the internal transcribed spacer (ITS) rDNA sequences showed that the isolated green mold corresponded to Penicillium brevicompactum (100.0%). This is the first report of green mold contamination caused by P. brevicompactum on H. marmoreus.

• Research in Plant Disease
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• v.25 no.4
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• pp.220-225
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• 2019

During the year 2018, the symptoms of bunch rot on Shine Muscat (Vitis vinifera L.) were observed in Kimcheon-si, Gyeongbuk province in Korea. The disease appears on the Shine Muscat as a black rot due to prolific fungal sporulation after it has invaded into the Shine Muscat which look completely empty and dryness. Colonies of these fungi are present on the Shine Muscat skin from fruit setting and increase in amount from early season to harvest, while become peak at ripening stage. To isolate the causal agent, small fragments (2 to 3 mm) of decayed tissue from the lesion margin were placed onto potato dextrose agar (PDA) plates. Fungal colonies on PDA produced dense white aerial mycelium and then covered with dark black conidial heads. These heads were large and radiate, and vesicles were globose (2.12-32.0×2.0-3.1 ㎛). Based on morphological and cultural characteristics, this fungus was identified as Aspergillus tubingensis. To confirm its identity, the internal transcribed spacer, β-tubulin, and RNA polymerase II was sequenced for molecular identification. BLAST search indicated 99% identity with A. tubingensis. The pathogenicity test on healthy grape of Shine Muscat produced bunch rot, as the original symptoms. To select effective fungicides for the control of brunch rot, an in vitro antifungal activity of seven fungicides were evaluated against the growth of A. tubingensis. Five fungicides (dipenoconazole, tebuconazole, metconazole, iminoctadine, and captan) exhibited significantly strong suppression of the mycelial growth of A. tubingensis.

• Research in Plant Disease
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• v.24 no.4
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• pp.302-307
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• 2018

From 2014 to 2016, approximately 5% of okra fruit were observed displaying gray mold symptoms at the research field of Jeollabuk-do Agricultural Research and Extension Services, Korea. The symptoms observed were water-soaked, brown or gray spots, and abundant mycelial with conidia appearing on the infected fruit. Initial infection commenced from the base of fruit and gradually moved to the pod, where it finally resulted in collapse. Colonies on potato dextrose agar were gray to grayish brown, felted and cottony expanding 65-80 mm after one week. The fungus formed several black sclerotia ranging $1.0-3.5{\times}0.5-3.0mm$ on the Petri dish after two weeks. The conidia were one-celled, ellipsoidal or ovoid, colorless or pale brown, and $6.2-15.4{\times}5.0-10.4{\mu}m$. Conidiophores arose solitary or in groups, straight or flexuous, septate, with an inflated basal cell brown to light brown, and measured $85-450{\times}10.0-40.0{\mu}m$. On the basis of the morphological characteristics and phylogenetic analyses of internal transcribed spacer rDNA, the fungus was identified as Botrytis cinerea Pers. Pathogenicity of a representative isolate was proved by artificial inoculation, fulfilling Koch's postulates. To our knowledge, this is the first report on the occurrence of B. cinerea on okra in Korea.

• Asian Journal of Turfgrass Science
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• v.21 no.2
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• pp.147-154
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• 2007

In March of 2004, gray snow mold (Typhula blight) caused by Typhula spp. occurred on perennial ryegrass (Lolium perenne L.) and Kentucky bluegrass (Poo pratensis L.) at MuJu golf courses in Jeonbuk Province. Leaves in the affected areas were matted together and frequently covered with white to grayish mycelia. Sclerotia were formed on the leaf blade, leaf sheath, or crown regions. The fungus isolated from the diseased leaf formed whitish mycelium, clamp connections, and light pink to brown, irregular-shaped small sclerotia of less than 1.4 mm in diameter, which are characteristic to Typhula incarnata. Optimum temperature ranges for mycelial growth were $5^{\circ}C$ to $15^{\circ}C$. The causal organism was confirmed to be T. incarnata as the partial sequence of its ribosomal RNA ITS1 (internal transcribed spacer) region was 91% homologous to those of T. incarnata in GenBank database. Out of the 14 fungicides tested fur antifungal activity in vitro, 10 fungicides including iprodione, tebuconazole, polyoxin D, flutolanil, hexaconazole, tolclofos-methyl, fosetyl-Al, mepronil, pencycuron+tebuconazole, and fenarimol completely inhibited fungal growth at their recommended concentrations. In the field test, these fungicides and others such as thifluzamide and thiram effectively controlled the gray snow mold of turfgrass with some variable degrees of control efficacies.

• Journal of Microbiology and Biotechnology
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• v.33 no.8
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• pp.1023-1029
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• 2023

Biosurfactants reduce surface and interfacial tension due to their amphiphilic properties and are an eco-friendly alternative for chemical surfactants. In this study, a new yeast strain JAF-11 that produces a biosurfactant was selected using drop collapse method, and the properties of the extracts were investigated. The nucleotide sequences of the strain were compared with closely related strains and identified based on the D1/D2 domain of the large subunit ribosomal DNA (LSU) and internal transcribed spacer (ITS) regions. Neodothiora populina CPC 39399^T, the closest species with strain JAF-11, showed a sequence similarity of 97.75% for LSU and 94.27% for ITS, respectively. The result suggests that the strain JAF-11 represents a distinct species that cannot be assigned to any existing genus or species in the family Dothideaceae. Strain JAF-11 produced a biosurfactant reducing the surface tension of water from 72 mN/m to 34.5 mN/m on the sixth day of culture and the result of measuring the critical micelle concentration (CMC) by extracting the crude biosurfactant was found to be 24 mg/l. The molecular weight 502 of the purified biosurfactant was confirmed by measuring the fast atom bombardment mass spectrum. The chemical structure was analyzed by measuring ¹H nuclear magnetic resonance (NMR), ¹³C NMR, and two-dimensional NMRs of the compound. The molecular formula was C₂₆H₄₆O₉, and it was composed of one octanoyl group and two hexanoyl groups to myo-inositol moiety. The new biosurfactant is the first report of a compound produced by a new yeast strain, JAF-11.

• Journal of Life Science
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• v.27 no.6
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• pp.661-672
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• 2017

Endophytic fungi are present in host plants and contribute to resistance to biotic and abiotic stress. Aquatic plants are living in aquatic environment such as saltwater or freshwater and exposed more water stress than other land plants. In this study, we investigated 4 wetlands in Jeju and collected 11 aquatic plants. Exogenous microbes were removed by preprocessing of plants and endophytic fungal strains were isolated from the plants. We isolated 126 fungal strains from Namsaengi-pond, 22 fungal strains from Sujangdong-marsh, 44 fungal strains from Yongsu-reservoir and 32 fungal strains from Gangjeongcheon. The fungal strains were identified using internal transcribed spacer (ITS) region and analyzed the phylogeny and diversity. Endophytic fungi isolated from plants of Namsaengi-pond were classified to 30 genera, 19 families, 12 orders, 7 classes and 4 phyla. Endophytic fungi of Sujangdong-marsh were classified to 11 genera, 11 families, 6 orders, 5 classes and 4 phyla. Endophytic fungi of Yongsu-reservoir were classified to 13 genera, 12 families, 7 orders, 5 classes and 4 phyla. Endophytic fungi isolated from Gangjeongcheon were classified to 9 genera, 7 families, 5 orders, 2 classes and 1 phyla. Overall, they were divided 40 genera and Alternaria, Colletotrichum and Fusarium were isolated from 4 sites in common. By investigating the endophytic fungi in aquatic plants, it is for baseline data that determination of diversity and the ecological distribution of endophytic fungi.

• Horticultural Science & Technology
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• v.31 no.6
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• pp.740-747
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• 2013

Leaf mold symptoms were found on commercial tomato cultivars carrying the Cf-9, a resistance gene to leaf mold pathogen Fulvia fulva in 2012 at Buyeo, Chungnam in Korea. Fifteen-fungal isolates were obtained from four Cf-9 cultivars of tomato including 'Cutie', 'otaerangdia', 'Unicorn' and 'Rapito'. Due to their same morphological appearances and colony color, nine isolates were selected and identified as F. fulva based on molecular analysis of the internal transcribed spacer rDNA sequence. Pathogenicity of the 15 isolates on five commercial cultivars carrying Cf-4, Cf-5, and Cf-9 were tested. All the isolates showed strong pathogenicity on Cf-9 cultivars, 'Cutie' and 'Dotaerangdia', and Cf-5 cultivar, 'Yoyocaptain'. In contrast, on Cf-4 cultivar, 'Superdotaerang', five isolates were virulent and the other isolates were not. In addition, two fungal isolates, infecting Cf-9 cultivar and non-infecting Cf-4 cultivar, were selected and their pathogenicity was tested on 17 commercial cultivars reported as tomato having Cf-9 resistance gene. Among them, 15 cultivars were susceptible and 2 cultivars were resistant. It is likely that the two cultivars include other resistance gene. To our knowledge, this is the first report on the occurrence of Cf-9 infecting F. fulfva strains in Korea.

• Journal of Life Science
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• v.26 no.12
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• pp.1446-1457
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• 2016

Wetlands exhibit intermediate characteristics of both terrestrial and aquatic ecosystems, and the biodiversity is rich in these unique biological habitats. The symbiotic relationships between plants and fungi that inhabit these wetlands play an important role in natural resource management, biodiversity, and conservation. Accordingly, the mujechi, having academic value for the study of the natural environment, was investigated in terms of genetic diversity of endophytic fungi, which inhabit the roots of wild plants. The internal transcribed spacer (ITS) region was amplified to identify fungal strains. In total, 226 strains were isolated and categorized into three phyla, seven classes, 10 orders, 22 families, and 31 genera. In plants by endophytic fungi were classified in Isachne globosa (Ig) to 19 genera, Scirpus karuisawensis (Sk) to 11 genera, Utricularia racemosa (Ur) to 19 genera, and one incertae sedis, Eriocaulon decemflorum (Ed) to 11 genera. The fungal taxa was identified the genera Acephala (19.9%), Tolypocladium (16.3%), Neopestalotiopsis (11.5%), and Perenniporia (7.1%). The fungal group isolated from Isachne globosa (Ig) grew the largest number of isolated fungal strains. After comprehensive evaluation, the endophytic fungal group from Utricularia racemosa (Ur) ranked highest in diversity analyses. From the roots of wild plant in mujechi-neup, it confirmed the distribution and diversity of endophytic fungi. This study provides the basic data to understand fungal community structure in peat wetlands.

• Journal of Microbiology and Biotechnology
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• v.23 no.7
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• pp.905-912
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• 2013

A novel species, Metschnikowia cibodasensis, is proposed to accommodate eight strains (ID03-$0093^T$, ID03-0094, ID03-0095, ID03-0096, ID03-0097, ID03-0098, ID03-0099, and ID03-0109) isolated from flowers of Saurauia pendula, Berberis nepalensis, and Brunfelsia americana in Cibodas Botanical Garden, West Java, Indonesia. The type strain of M. cibodasensis is ID03-$0093^T$ (= NBRC $101693^T$ =UICC $Y-335^T$ = BTCC-$Y25^T$). The common features of M. cibodasensis are a spherical to ellipsoidopedunculate shaped ascus, which contains one or two needle-shaped ascospores, and lyse at maturity. Asci generally develop directly from vegetative cells but sometimes from chlamydospores. The neighbor-joining tree based on the D1/D2 domain of nuclear large subunit (nLSU) ribosomal DNA sequences strongly supports that M. cibodasensis (eight strains) and its closest teleomorphic species, M. reukaufii, are different species by a 100% bootstrap value. The type strain of M. cibodasensis, ID03-$0093^T$, differed from M. reukaufii NBRC $1679^T$ by six nt (five substitutions and one deletion) in their D1/D2 region of nLSU rDNA, and by 18 nt (five deletions, four insertions, and nine substitutions) in their internal transcribed spacer regions of rDNA, respectively. Four strains representative of M. cibodasensis (ID03-$0093^T$, ID03-0095, ID03-0096, and ID03-0099) showed a mol% G+C content of $44.05{\pm}0.25%$, whereas that of M. reukaufii NBRC $1679^T$ was 41.3%. The low value of DNA-DNA homology (5-16%) in four strains of M. cibodasensis and M. reukaufii NBRC $1679^T$ strongly supported that these strains represent a distinct species.

• The Korean Journal of Mycology
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• v.46 no.2
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• pp.193-199
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• 2018

The fungus, Podosphaera pannosa, was identified in 1991 as the cause of powdery mildew symptoms on peach (Prunus persica var. persica) fruit from Korea based on the morphological characteristics of the conidial state. Recently, however, in Serbia and France, the cause of 'rusty spot' found on peach fruit was identified as P. leucotricha, and the cause of 'powdery mildew' on nectarine (Prunus persica var. nucipersica) fruit was identified as P. pannosa. To confirm the identity of the Korean pathogen, we collected four samples of powdery mildew from Korean peach fruit: three with the 'powdery mildew' symptom and one with the 'rusty spot' symptom. Morphological examination of the four samples confirmed P. pannosa as the pathogen. Internal transcribed spacer sequences of rDNA were analyzed for molecular characterization. A phylogenetic tree showed that the Korean isolates were clustered into a clade containing P. pannosa from Rosa species, with high sequence similarities of more than 99%. Thus, we showed that the powdery mildew and rusty spot symptoms on peach fruits from Korea are associated with P. pannosa.