• Korean Journal Plant Pathology
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• v.11 no.1
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• pp.90-93
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• 1995

Leaf blotch of Welsh onion was observed at a farmer's field at Kangnung in July 1990. Further collection o the diseased materials was made in 1993 and 1994. The symptom initially appeared as discolored spot and later yellowish blotch with the long axis parallel to the leaf veins, which turned to sooty colored concentric lesion due to heavy production of conidiophores and conidia. Cladosporium allii-cepae (Ranojevic) M. B. Ellis was repeatedly isolated from the leaf lesions. Healthy Welsh onion inoculated with conidial suspension of the fungus produced the typical symptom 10 days after inoculation. Koch's postulates were fulfilled by reisolation of the fungus. This is the first report of a Cladosporium leaf blotch of Welsh onion in Korea.

• Mycobiology
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• v.50 no.3
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• pp.155-165
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• 2022

Penicillium vietnamense sp. nov. was isolated from Nha Trang Bay, Vietnam in June 2017. It is phylogenetically distinct from the sister species of Penicillium section Charlesia series Indica based on multi-locus sequence typing results using internal transcribed spacer, large subunit ribosomal RNA, b-tubulin, calmodulin, and RNA polymerase II second largest subunit regions. It showed strong growth on Czapek yeast autolysate agar at 37 ℃, a strong acid production on Creatine sucrose agar, and produced short stipes, small vesicles, and subglobose to globose conidia delicately roughened with very short ridges. As the first novel marine fungi species described from Vietnam and discovered in a unique environment, the data could be significant for understanding the taxonomy and geographical distribution of marine fungi in tropical coastal systems such as Vietnam.

• The Plant Pathology Journal
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• v.32 no.5
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• pp.388-395
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• 2016

The most serious aerial disease of garlic is leaf blight caused by Stemphylium spp. Geographical variation in the causal agent of this disease is indicated. Stemphylium vesicarium has been reported in Spain, whereas S. solani is the most prevalent species recorded in China. In this study, Stemphylium isolates were obtained from symptomatic garlic plants sampled from the main Spanish production areas. Sequence data for the ITS1-5.8S-ITS2 region enabled assignation of the isolates to the Pleospora herbarum complex and clearly distinguished the isolates from S. solani. Conidial morphology of the isolates corresponded to that of S. vesicarium and clearly discriminated them from S. alfalfae and S. herbarum on the basis of the size and septation pattern of mature conidia. Conidial morphology as well as conidial length, width and length:width ratio also allowed the Spanish isolates to be distinguished from S. botryosum and S. herbarum. Control of leaf blight of garlic is not well established. Few studies are available regarding the effectiveness of chemical treatments to reduce Stemphylium spp. incidence on garlic. The effectiveness of nine fungicides of different chemical groups to reduce Stemphylium mycelial growth in vitro was tested. Boscalid + pyraclostrobin (group name, succinate dehydrogenase inhibitors + quinone outside inhibitors), iprodione (dicar-boximide), and prochloraz (demethylation inhibitors) were highly effective at reducing mycelial growth in S. vesicarium with $EC_{50}$ values less than 5 ppm. In general, the effectiveness of the fungicide was enhanced with increasing dosage.

• The Plant Pathology Journal
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• v.21 no.3
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• pp.221-228
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• 2005

A total of 179 isolates of Trichoderma spp. were collected from oyster mushroom substrates in Korea. On the basis of morphological and cultural characteristics, Trichoderma isolates were divided into seven groups, namely T. atroviride, T. citrinoviride, T. harzianum, T. longibrachiatum, T. virens, and two unidentified species, referred to as Trichoderma sp. 1 and 2. The predominant species was Trichoderma sp. 2 (n=86) followed by Trichoderma sp. 1 (n=52). Trichoderma sp. 1 and 2 were morphologically distinct not only from the other species of Trichoderma reported but also from each other in the characteristics such as mycelial growth rate, colony appearance, shape of conidia and conidiophores and branching pattern of phialides, although branching pattern of phialides of Trichoderma sp. 1 was similar to that of T. harzianum. In virulence test, the degree for compost colonization of Trichoderma sp. 2 was significantly greater than that of the other Trichoderma species. Trichoderma sp. 2 was found to be the main cause of green mold disease in oyster mushroom production. More work including molecular characterization is needed to confirm the species of Trichoderma sp. 1 and 2.

• Korean Journal Plant Pathology
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• v.14 no.3
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• pp.268-277
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• 1998

The production of Korean ginseng, one of the most important medicinal root crops, is limited by many factors including soil sickness, root rots in fields as well as during storage prior to consumption. Although much research has been conducted on the diseases in field condition, little information is available on the control of postharvest roots rots. To obtain better management strategy of postharvest root rots in ginseng, biological control using antagonistic bacteria was attempted. Of 208 bacteria obtained form suppressive soil samples, 4 were selected based on the inhibitory effect on mycelial growth of two major causal fungi for postharvest root rots in ginseng, Botrytis cinerea and Fusarium solani. The culture filtrates of these bacterial antagonists greatly inhibited the conidial germination of both pathogenic fungi and produced abnormal morphology such as swollen germ tubes in F. solani and vacuolation of nongerminated conidia in B. cinerea. The population levels of bacterial antagonists on the ginseng roots were gradually increased up to 8 days of incubation. Postharvest root rots of ginseng caused by f. solani and B. cinerea were controlled in dipping tests in the ranges of 60∼80% by antagonistic Bacillus spp. obtained from suppressive soil. These results suggest that biological control using these antagonistic bacteria would be an alternative strategy to control postharvest root rots in ginseng.

• The Korean Journal of Mycology
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• v.48 no.2
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• pp.87-93
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• 2020

A fungal strain designated KNU-WDM2A2 was isolated from mosquitoes in Gimcheon, Korea. The pure culture was transferred to potato dextrose agar (PDA) and synthetic nutrient agar (SNA) media and attained a diameter of 90 mm after 10 days of incubation at 25℃. The colonies were whitish to light pink and cottony to wooly, with an abundant production of aerial mycelia. The strain produced hyaline to slightly yellowish conidiophores that were rough-walled and branched, with conidiogenous cells arising terminally or laterally. Conidia were unicellular, hyaline to light brown, smooth, and oval or ovoid to clavate, with a size of 4.1-6.9×2.5-3.3 ㎛ (n=65). A phylogenetic analysis was conducted using the internal transcribed spacer (ITS) regions and 28S rDNA of large subunit (LSU) sequences, to support the cultural and morphological characteristics. The KNU-WDM2A2 strain was identified here as Biscogniauxia petrensis, new to Korea.

• The Plant Pathology Journal
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• v.16 no.3
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• pp.137-141
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• 2000

A causal fungus of turfgrass blight was isolated from the infected leaves of zoysiagrass (Zoysia japonica Steud.) and identified as Nigrospora sphaerica (Sacc.) Mason by using a light misroscope. Its conidia are large (14-20 ${\mu}{\textrm}{m}$ diameter), shiny, black, aseptate, and smooth-walled spheres. The fungus caused typical blighting symptoms on the two turfgrass plants of bermudagrass (Cynodon dactylon (L.) Pers.) and bentgrass (Agrostis palustris Huds.). The fungus was found to produce a phytotoxic subtance to be associated with the pathogenic mechanism. A phytotoxin was isolated from the liquid cultures of N. sphaerica by repeated silica gel column chromatography and its structure was determined to be 5, 6-dihydro-5-hydroxy-6-propenyl-2H-pyr-2-one (T-3 compound). It was not a host-specific toxin showing phytotoxic effects to various plants inclusing turfgrasses in the leaf-wounding assay, the whole plant test, and the cellular leakage test. The compound caused leaf tip dieback symptoms in turfgrass plants similar to those caused by the pathogen. Thus, T-3 compound is thought to be involved in the development of Nigrospora blight.

• 한국균학회소식:학술대회논문집
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• 2015.11a
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• pp.28-28
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• 2015

Asexual reproduction or conidiation in aspergilli is a primary mean to produce their progenies that is environmentally and genetically controlled tightly. Previously, intensive researches in the model fungus Aspergillus nidulans disclosed some genes playing important roles in asexual and sexual development. Among them, one gene encoding a putative helix-loop-helix (HLH) transcription factor, named ndrA, has been isolated and characterized as a downstream regulator of developmental master regulator NsdD. By using comparative genome search of A. niduans NdrA protein, its orthologues have been identified in A. fumigatus and A. flavus, respectively (AfudrnA and AfldrnA). Deletion of the ndrA genes in both Aspergillus species made them unable to produce the conidia yet abundant production of sclerotia in A. flavus. Complementation of ndrA deletion strains by intact ndrA ORFs has restored the conidiation as in the control strains. In A. fumigatus, ndrA deletion also resulted in loss of conidiation phenotype. Northern analyses showed that the ndrA genes in both Aspergillus species are highly expressed at the early stage of the conidiation. Interestingly, the ndrA genes were found to be necessary for the proper expression of brlA genes. Antifungal sensitivity test revealed that the ndrA genes might be responsible for the sensitivity or resistance to some antifungal agents. However, ndrA deletion did not greatly influence the growth in both strains. And the A. flavus ndrA gene did not affect the aflatoxin production. Taken together, ndrA genes in Aspergillus species could be an important positive regulator of conidiation under the regulation of the nsdD gene yet upstream of the brlA gene.

• The Korean Journal of Mycology
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• v.25 no.4 s.83
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• pp.320-329
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• 1997

Botrytis cinerea isolates obtained from infected plants of cucumber, tomato, and strawberry were divided into three groups (sporing, sclerotial, and mycelial types). Of which sclerotial types were the major group. There were no correlations between morphological phenotypes and responses to benzimidazole and dicarboximide fungicides. External structure of conidia of three phenotypes by scanning electron microscope was the same with verrucose surface. Mycelial type was the most virulent on fruits of eggplants. Comparative tests were carried out to examine correlations between the virulence and production of fungal enzymes such as phenol oxidases, pectin methyl esterases (PME), amylases, cellulases, ureases, ${\beta}-glucosidases$, and proteinases. There was no correlation among the phenotypes in production of phenol oxidases and ${\beta}-glucosidases$. However, there were significantly different from each other in PME, amylase, cellulase, urease, and protease activity.

• Microbiology and Biotechnology Letters
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• v.26 no.4
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• pp.290-296
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• 1998

Interspecific hybrids between Aspergillus oryzae var. oryzae and Penicillium chrysogenum (Tyr$\^$-/), high alkaline protease producing fungi, were obtained by nuclear transfer technique. Nuclei isolated from the wild type Aspergillus oryzae var. oryzae strain were transferred into auxotrophic Penicillium chrysogenum mutants and selected the new strains showing an increased protein degrading capability. Maximum production of protoplasts were obtained by 1% Novozym 234 at $30^{\circ}C$ for 3 hours and the most effective osmotic stabilizers for the isolation of protoplasts were 0.6M KCl. Frequencies of hybrid formation by nuclear transfer were 1.3${\times}$10$\^$-3/∼2.8${\times}$10$\^$-3/. They could be suggested as an aneuploid by the observation of genetic stability, conidial size, DNA content, and nuclear strain. The hybrids showed 1.1～2.2 fold higher alkaline pretense activities than parental strains.