• The Korean Journal of Mycology
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• v.26 no.1 s.84
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• pp.31-38
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• 1998

Since 1990, destructive yellow rots on Ganoderma lucidum caused by a soilborne fungus have been occurred in major cultivation areas of Korea. Incidences of the disease were 61% in Chulwon and 94% in Kanghwa area where the mushroom has been cultivated for 10 years, whereas the disease has not been found yet in new cultivation areas such as Moonkyung and Hongsung. when severely infected, inner tissues of bed-logs showed severe yellow and fruiting bodies of the mushroom was not produced. Infected tissues of bed-logs were readily distinguished from those of healthy ones by a distinctive brown border line. When the disease progressed, mycelia of Ganoderma lucidum were totally destroyed, and abundant ascocarps of the pathogen were formed inside the tissues of bed-logs showing yellowish green. The fungus derived from a single ascospore strongly lysed mycelia of Ganoderma lucidum growing on bottle media, and non-volatile components secreted by the pathogen were also highly inhibitory to mycelial growth of the mushroom fungus. The pathogen was identified as Arthrographis cuboidea based on its distinctive cultural and morphological characters. The fungus produced arthroconidia and unbrached conidiophores. The width of fungal conidia was distinctively wide as compared with the length. Colonies of the fungi were pale yellow to yellowish green on agar media. As a causal pathogen of yellow rot of Ganoderma lucidum., this fungus has not been reported yet in Korea.

• The Korean Journal of Mycology
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• v.42 no.4
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• pp.262-268
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• 2014

A fungal isolate DUCC5000 from a garden plant Pachysandra terminalis was identified as Paraconiothyrium brasiliense based on the results of morphological and molecular studies. The fungus formed brown to black conidiomata of (0.2-0.7)-2(-3.5) mm singly or as a group on PDA. Conidia measured $2-5{\times}1.8-3{\mu}m$ in size, hyaline, ellipsoid to short-cylindrical, and rounded at both ends. The internal transcribed spacer (ITS) DNA of the isolate shared 100% nucleotide sequence homology with those of known P. brasiliense isolates. Phylogenetic tree inferred from the ITS sequence analysis showed that the DUCC5000 isolate formed a clade with known isolates of P. brasiliense. The fungal mycelia grew better on oatmeal agar than on MEA and PDA. On PDA media under various pH conditions, fungal mycelial growth was observed at pH 9. Colony morphology of the fungus tended to alter depending on the kinds of nutrient media and pH condition. On chromagenic media, the fungus demonstrated its ability to produce extracellular enzymes including amyalse, avicelase, ${\beta}$-glucosidase, protease, and xylanase. However, in pathogenicity testing, no disease symptoms were observed on the leaves of P. terminalis. This strain is the first report on P. terminalis in Korea.

• Research in Plant Disease
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• v.18 no.2
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• pp.109-116
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• 2012

A bacterial strain antagonistic to some fungal phytopathogens was isolated from the stem of a Persimmon tree in Yeongam, Korea. This bacterium was identified as Bacillus subtilis by 16S rRNA gene sequencing and designated as B. subtilis GDYA-1. In in vivo experiment, the fermentation broth exhibited antifungal activities against Magnaporthe oryzae on rice plants, Phytophthora infestans on tomato plants, and Puccinia recondita on wheat plants. We isolated one antifungal compound and its chemical structure was determined by mass and $^1H$-NMR spectral data. The antifungal substance was identified as benzoic acid. It inhibited mycelial growth of M. oryzae, Rhizoctonia solani, Sclerotinia sclerotiorum, and P. capsici with minimum inhibition concentration (MIC) values, ranging from 62.5 to 125 ${\mu}g/ml$. Moreover, the substance effectively suppressed Phytophthora blight of red pepper caused by P. capsici in a pot experiment. To the author's knowledge, this is the first report on the antifungal activity of benzoic acid against phytopathogenic fungi. Benzoic acid and B. subtilis GDYA-1 may contribute to environmental-friendly protect crops from phytopathogenic fungi.

• The Plant Pathology Journal
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• v.26 no.4
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• pp.313-320
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• 2010

Genetic instability of the rice blast fungus Magnaporthe oryzae has been suggested as a major factor underlying the rapid breakdown of host resistance in the field. However, little information is available on the mechanism of genetic instability. In this study, we assessed the stability of repetitive DNA elements and several key phenotypic traits important for pathogenesis after serially transferring two isolates though rice plants and an artificial medium. Using isolate 70-15, we obtained a total of 176 single-spore isolates from 10 successive rounds of culturing on artificial medium. Another 20 isolates were obtained from germ tubes formed at the basal and apical cells of 10 three-celled conidia. Additionally, 60 isolates were obtained from isolate KJ201 after serial transfers through rice plants and an artificial medium. No apparent differences in phenotypes, including mycelial growth, conidial morphologies, conidiation, conidial germination, appressorium formation, and virulence, or in DNA fingerprints using MGR586, MAGGY, Pot2, LINE, MG-SINE and PWL2 as probes were observed among isolates from the same parent isolate. Southern hybridization and sequence analysis of two avirulence genes, AVR-Pita1 and AVR-Pikm, showed that both genes were also maintained stably during 10 successive generations on medium and plants. However, one reversible loss of restriction fragments was found in the telomere-linked helicase gene (TLH1) family, suggesting some telomere regions may be more unstable than the rest of the genome. Taken together, our results suggest that phenotype and genotype of M. oryzae isolates do not noticeably change, at least up to 10 successive generations on a cultural medium and in host plants.

• Research in Plant Disease
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• v.14 no.1
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• pp.57-60
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• 2008

A rhizopus soft rot caused by Rhizopus stolonifer occurred sporadically on apple fruits (Malus pumila var. dulcissima Koidz.) at a wholesale market of agricultural products in Jinju, Korea in 2006 and 2007. Infected fruits were rapidly water-soaked, softened and rotted. The symptoms were initiated mainly from wounds or cracks occurred at harvest time. Sporangiophores were $950{\sim}1,900\;{\mu}m$ in length and $12{\sim}22\;{\mu}m$ in width. Sporangia were globose or hemispheric and $82{\sim}185\;{\mu}m$ in size. The color of sporangia was white and cottony at first and gradually turned to brownish black, bearing abundant spores when matured. Columella were hemispheric and $70{\sim}85\;{\mu}m$ in size. Sporangiospores were irregular round or oval, brownish-black streaked and $8{\sim}18{\times}7{\sim}8\;{\mu}m$ in size. Optimum temperature for mycelial growth of the fungus on PDA was $25^{\circ}C$. On the basis of mycological characteristics and pathogenicity to apple the causal fungus was identified as Rhizopus stolonifer (Ehrenb.) Vuill. This is the first report of Rhizopus soft rot by R. stolonifer on Fuji apple in Korea.

• Weed & Turfgrass Science
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• v.1 no.4
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• pp.69-75
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• 2012

In response of fungicides for control of gray snow mold, isolates of Typhula incarnata were collected from three golf courses in 2012 Yongpyeong, Korea and tested for sensitivity to propiconazole, tebuconazole and azoxystrobin fungicides. Four discriminatory concentrations were used to detect in vitro sensitivity of 50 isolates. Mean 50% effective concentration inhibiting mycelial growth ($EC_{50}$) values for tebuconazole was the lowest among the three fungicides. The $EC_{50}$ value of tebuconazole ranged from 0.0005 ${\mu}g\;ml^{-1}$ to 0.014 ${\mu}g\;ml^{-1}$ with a mean of 0.0048 ${\mu}g\;ml^{-1}$. The mean $EC_{50}$ values of propiconazole in triazole family was 0.5825 (0.78-1.651) ${\mu}g\;ml^{-1}$. $EC_{50}$ value of azoxystrobin ranged from 0.0017 ${\mu}g\;ml^{-1}$ to 0.131 ${\mu}g\;ml^{-1}$ with a mean of 0.0278 ${\mu}g\;ml^{-1}$. There was no correlation among $EC_{50}$ values for propiconazole, azoxystrobin and tebuconazole indicating no cross-resistance relationships with each other. Results of this study were confirmed no resistance isolates in vitro sensitivity of T. incarnata of three fungicides in Yongpyeong.

• Research in Plant Disease
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• v.12 no.2
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• pp.69-74
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• 2006

Basal rot of freesia caused by a Sclerotium sp. occurred at Incheon areas. Incidence of the disease reached up to 45% and averaged 17.0% in the fields. Typical symptoms consisted of sheath dry and leaf blight due to rots on basal leaves. The causal fungus was identified as Sclerotium sp. based on following mycological characteristics. The fungus formed sclerotia on cultural media and plant tissues, but did not produce asexual spores. On cultural medium, aerial mycelia of the fungus changed color from white to clay with cultural age and smelled musty odor. Numerous irregular and elliptical black microsclerotia of the fungus were formed on potato dextrose agar (PDA) after 5 days of incubation at $25^{\circ}C$ and sized $115{\sim}200{\times}95{\sim}150 (av. 145{\sim}126.5){\mu}m$. The fungus grew at $10{\sim}32^{\circ}C$ and $pH 4.0{\sim}8.5$. However, the optimal temperature and pH for mycelial growth of the fungus were $24^{\circ}C$ and 5.5 respectively. The isolate showed present pathogenicity to not only freesia but gladiolus in the pathogenicity test, and the symptoms were similar to those observed in the fields. Basal rot of freesia caused by Sclerotium sp. is firstly reported in Korea.

• Korean Journal of Breeding Science
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• v.42 no.6
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• pp.711-716
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• 2010

'Sanggang', a new cultivar of Agrocybe aegerita, was bred with mating between monokaryotic strains isolated from 'GMAG45109' and 'GMAG45107' in Mushroom Research Station, Gyonggi Province A.R.E.S. in 2009. The optimum temperature for the mycelial growth of 'Sanggang' was 26 to 28$^{\circ}C$ on PDA(potato dextrose agar) medium. The optimum temperature for the primordia formation and fruiting body development of 'Sanggang', was 18 to 20$^{\circ}C$. In the bottle cultivation of 'Sanggang', the period of spawn running was around 38 days at 22 to 23$^{\circ}C$ and the period from scratching of inoculum to harvest was 12 days. These characteristics of 'Sanggang' were not different from those of 'Mihwang' (control). 'Sanggang' had brown-colored pileus, whereas 'Mihwang' had yellowish brown-colored one. In bottle cultivation, 'Sanggang' hada little smaller but stronger stipe and pilus than 'Mihwang', and 'Sanggang', as well as 'Mihwang', had upright stipe. And 'Sanggang' was shown to have lower veil opening ratio than that of 'Mihwang' at harvest time.The yield of fruiting bodies of 'Sanggang' was 134 g/850ml bottle, which was similar to that of 'Mihwang'. Resistance of'Sanggang' against Trichoderma spp., as well as 'Mihwang', was weak. Freshness of 'Sanggang' was maintained for 13 days under storage temperature 4$^{\circ}C$, while that of 'Mihwang' was maintained for 10 days.

• Korean Journal of Breeding Science
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• v.42 no.3
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• pp.288-293
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• 2010

'Cham', a new cultivar of Agrocybe aegerita, was bred by crossing between monokaryotic strains isolated from GMAG45021 and 'Beodeulsongi1ho' in Mushroom Research Station, Gyonggi Province A.R.E.S. in 2007. The optimum temperature for the mycelial growth of 'Cham' was 26 to $28^{\circ}C$ on PDA medium, whereas that of 'Beodeulsongi1ho'(control) was 24 to $26^{\circ}C$. The optimum temperature for the primordial formation and fruiting body development of 'Cham', as well as 'Beodeulsongi1ho', was 18 to $20^{\circ}C$. In the bottle cultivation, the spawn run period of 'Cham' at 22 to $23^{\circ}C$ was around 38 days and the period from scratching of inoculum to harvest was 12 days. These characteristics of 'Cham' were not different from those of 'Beodeulsongi1ho'. However, 'Cham' had more dark brown-colored, and thicker and stronger pileus, and longer and thicker stipe compared to that of 'Beodeulsongilho'. Freshness of 'Cham' was maintained for 10 days at the storage temperature of $4^{\circ}C$, while that of 'Beodeulsongi1ho' was maintained for 8 days. Moreover, the yield of fruiting bodies of 'Cham' was $141g/850m{\ell}$ bottle, which was similar to that of 'Beodeulsongi1ho'. Both 'Cham' and 'Beodeulsongilho' have lower resistivity against Trichoderma virens and Trichoderma harzianum.

• Journal of Mushroom
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• v.17 no.3
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• pp.126-131
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• 2019

This study sought to identify the optimum substrate composition for the stable bottle cultivation of Sparassis latifolia. The main substrate was fermented larch sawdust. Six nutrient sources were mixed at a maximum volume ratio of 20%. The fresh weight of fruit body was the highest at 128.5 g for GMSL69033 and 126.6 g for 'Neoul' in the treatments of beet pulp and corn flour in a volume ratio of 15:5. In addition, the total cultivation period was 94 days, which was shorter than that required for other treatments. The selected substrate characteristics were pH 4.7, C:N (carbon to nitrogen) ratio of 106:4, moisture content of 70%, and air filling porosity of 38%. We plan to develop new income items through research on mycelial incubation and fruit body growth conditions.