• The Plant Pathology Journal
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• v.35 no.2
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• pp.156-163
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• 2019

Our study investigated the available chlorine content, contact time and difference among strains of each pathogen for sodium hypochlorite (NaOCl) to control chemically against soil-borne fungal pathogens, such as Phytophthora rot by Phytophthora cactorum, violet root rot by Helicobasidium mompa, and white root rot by Rosellinia necatrix, causing die-back symptom on apple trees. As a result, the colony growth of Phytophthora cactorum was inhibited completely by soaking over 5 s in 31.25 ml/l available chlorine content of NaOCl. Those of H. mompa and R. necatrix were inhibited entirely by soaking over 160 s in 62.5 and 125 ml/l available chlorine content in NaOCl, respectively. Also, inhibition effect on available chlorine in NaOCl among strains of each soil-borne pathogen showed no significant difference and was similar to or better than that of fungicides.

• Research in Plant Disease
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• v.19 no.3
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• pp.177-182
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• 2013

Resvestrol has been known to inhibit bacterial and fungal growth in vitro, and can be accumulated in plant to concentrations necessary to inhibit microbial pathogens. Hence, stilbene synthase gene has been used to transform to synthesize resveratrol in heterologous plant species to enhance resistance against pathogens. In the present study, we investigated the antimicrobial activities of resveratrol and piceid to bacterial and fungal pathogens, which causing severe damages to rice plants. In addition, disease resistance was compared between transgenic rice varieties, Iksan 515 and Iksan 526 transformed with stlibene synthase gene and non-transgenic rice varieties, Dongjin and Nampyeong. Minimum inhibitory concentration of resveratrol for Burkolderia glumae was 437.5 ${\mu}M$, and the mycelial growth of Biplaris oryzae was slightly inhibited at concentration of 10 ${\mu}M$. However, other bacterial and fungal pathogens are not inhibited by resveratrol and piceid. The expression of the stilbene synthase gene in Iksan 515 and Iksan 526 did not significantly enhanced resistance against bacterial grain rot, bacterial leaf blight, sheath blight, and leaf blight. This study is the first report on the effect of resveratrol and piceid against pathogens of rice plant, and changes of disease resistance of transgenic rice plants transformed with stilbene synthase gene.

• Journal of the Korean Wood Science and Technology
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• v.48 no.1
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• pp.50-60
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• 2020

Fungi are wood-decaying organisms, and this is an important trait that should be considered in wood utilization. When fungi attack wood, it decreases the quality of the wood. The use of metal screws has become an important part of woodworking. The ability of fungi to decay wood and damage metal screws that are embedded into wood is varied. In this study, eight fungal species were evaluated with respect to their ability to decay Parashorea smythiesii and P. tomentella wood. In addition, the effect of fungi on corroding metal screws was determined using the Kolle flask method. The evaluation showed that the fungal species Schizophyllum commune, Pycnoporus sanguineus, and Polyporus arcularius were highly capable of decaying Parashorea spp. woods. The greatest wood weight loss occurred with the heartwood of P. tomentella exposed to S. commune. Based on the classification of wood resistance against fungal attack, the two Parashorea spp. were classified as moderately resistant woods (class III). Schizophyllum commune was classified as highly capable of decaying wood that was embedded with metal screws and was highly capable of corroding metal screws placed in fungi-culture media. The greatest weight of rust powder formed because of screw corrosion was obtained from screw-embedded wood exposed to S. commune. Additionally, the most severe corrosion of metal screws that were embedded into woods was caused by the activities of P. arcularius. Moreover, the average weight loss of screw-embedded wood was greater than that of unscrewed wood.

• Research in Plant Disease
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• v.26 no.1
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• pp.38-43
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• 2020

The genome of the rice blast fungus Magnaporthe oryzae contains several types of transposable elements (TEs), and some TEs cause genetic variation that allows M. oryzae to evade host detection. We studied how five abundant TEs in rice pathogens, Pot3, Pot2, MAGGY, Line-like element (MGL) and Mg-SINE, are expressed under diverse conditions related to growth, development, and stress. Expression of Pot3 and Pot2 was activated in germinated conidia and mycelia treated with tricyclazole. Retrotransposon MAGGY was highly expressed in appressoria and tricyclazole-treated mycelia. MAGGY and Pot2 were also activated during the early and late stages of perithecia development. MGL was up-regulated in conidia and during conidial germination but not during appressorium formation. No noticeable expression of Mg-SINE was observed under most conditions. Our results should help investigate if and how condition-specific expressions of some TEs contribute to the biology and evolution of M. oryzae.

• Journal of Apiculture
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• v.34 no.2
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• pp.125-129
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• 2019

Honey bees are important pollinators in agriculture, but are threatened by the pathogen Ascosphaera apis, which causes chalkbrood. Despite attempts to control this fungus using synthetic fungicides, none of them have been proven to be completely effective. Among 640 natural compounds that we tested, 4-hydroxyderricin (MIC=3.125, 6.25 mg/L after 24 h and 48 h growth, respectively) exhibited the strongest anti- Ascosphaera apis activity, followed by acetylshikonin (MIC=12.5 mg/L for 24 h and 48 h growth). 4-Hydroxyderricin showed selective growth inhibition of Ascosphaera apis and Rhizopus oryzae among tested fungus strains. Treatment 4-hydroxyderricin with miconazole revealed a synergistic effect (FICI=0.65±0.13 at 48 h incubation). These findings suggest that 4-hydroxyderricin, which has antifungal activity against Ascosphaera apis but few other fungal species, can effectively control infectious fungal diseases. Combined treatment of bees with 4-hydroxyderricin and miconazole could reduce cytotoxicity and improve the cost effectiveness of treatment.

• Mycobiology
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• v.45 no.3
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• pp.129-138
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• 2017

In this study, we aimed to characterize fungal samples from necrotic lesions on collar regions observed in different sweetpotato growing regions during 2015 and 2016 in Korea. Sclerotia appeared on the root zone soil surface, and white dense mycelia were observed. At the later stages of infection, mother roots quickly rotted, and large areas of the plants were destroyed. The disease occurrence was monitored at 45 and 84 farms, and 11.8% and 6.8% of the land areas were found to be infected in 2015 and 2016, respectively. Fungi were isolated from disease samples, and 36 strains were preserved. Based on the cultural and morphological characteristics of colonies, the isolates resembled the reference strain of Sclerotium rolfsii. Representative strains were identified as S. rolfsii (teleomorph: Athelia rolfsii) based on phylogenetic analysis of the internal transcribed spacer and large subunit genes along with morphological observations. To test the pathogenicity, sweetpotato storage roots were inoculated with different S. rolfsii strains. 'Yulmi' variety displayed the highest disease incidence, whereas 'Pungwonmi' resulted in the least. These findings suggested that morphological characteristics and molecular phylogenetic analysis were useful for identification of S. rolfsii.

• Korean Journal of Veterinary Research
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• v.42 no.3
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• pp.363-370
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• 2002

For the development of diagnostic polymerase chain reaction (PCR) to fungal infection by dermatophytes Trichophyton and Microsporum, detection of the fungal DNA by PCR and analysis of the DNA pattern were undertaken in the present study. A total of 15 strains were tested and those consisted of 3 reference strains and 12 isolates such as: reference strains of T mentagrophytes (downy type, ATCC 9533), T rubrum (IFO 6204) and M gypseum (ATCC 9083), and each isolate of T mentogrophytes (powdery type), T mentagrophytes (granular type), T mentogrophytes (purple-red type), T rubrum, T raubitschekii, T tonsurans, T equinum, T ajelloi, T verrucosum, M cookei, M nanum and M gypseum. The DNA were purely isolated from all strains of Trichophyton spp. and Microsporum spp. by a simple method partly consisted of disruption of fungal cells by lyophilization and grinding and extraction of fungal DNA without phenol treatment which is a routine procedure in DNA isolation. For the detection of fungal DNAs, optimal condition of PCR was determined as preheating once at $94^{\circ}C$ for 5 min, 35 cycles of denaturation at $94^{\circ}C$ for 1 min, annealing at $38^{\circ}C$ for 1 min and polymerization at $72^{\circ}C$ for 2 min, and 1 cycle of final extension at $72^{\circ}C$ for 5 min. In PCR using arbitrary primers AP-1 (5' ACCCGACCTG3') and AP-2 (5' ACGGGCCAGT3'), DNAs in various numbers and sizes were detected from different species of Trichophyton and Microsporum, while DNAs in similar size were also detected in all strains of Trichophyton spp. and Microsporum spp. There were unique DNAs observed from certain dermatophytes by AP-1 such as 1,900 bases in T rubrum, 950 and 1,100 bases in T raubitscheldi, 2,100 bases in T equinum, 400 bases in T verrucosum and 1,150 bases in M gypseum. The unique DNAs were also observed by AP-2 such as 1,200 bases in T ajelloi, 250 bases in T verrucosum, 1,150 bases in M cookei and 2,000 bases in M nanum. The results indicated that PCR can detect a specific DNA from certain Trychophyton and Microsporum spp, which can be the information for further development of diagoomc PCR to dennatophytes.

• Journal of Animal Science and Technology
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• v.46 no.5
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• pp.763-772
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• 2004

The patterns of fungal growth and fiber digestion under the microscope, and tile productions of fibrolytic enzyme were studied in an in vitro culture with Neocallimastix frontalis SA when either filter paper or rice straw was provided as sole energy source. Under the microscopic observation, active zoospores attachment, sporangium development and complex rhizoidal system were founded on the surface and at the edge of filter paper. After 7 days of incubation, a reduced fiber mass, a decreased fiber cohesion and a weakened fiber structure by fungal digestion were clearly observed. Similar fungal development was observed with rice straw, but fungal growth and digestion took place mostly on the damaged and exposed portion of rice straw. Although there were some differences in absolute concentration and pattern, the concentration of both cellulase and xylanase increased with incubation time with the higher activity being obtained with filter paper. Their differences were large especially after 48 and 96hr of incubation(P< 0.05). The filter paper was more good inducer of cellulolytic and xylanolytic enzymes compared with complex substrate, rice straw. These findings suggest that the filter paper is the better energy source for N frontalis than the complex substrate, and structural disintegration by physical process is able to help rumen fungal growth on the lignified roughage although anaerobic rumen fungi have mechanical and enzymatic functions for fiber digestion.

• Journal of Microbiology and Biotechnology
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• v.18 no.10
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• pp.1729-1734
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• 2008

Chitosan, a cationic polysaccharide, has been widely used as a dietary supplement and in a variety of pharmacological and biomedical applications. The antifungal activity and mechanism of action of low molecular weight water-soluble chitosan (LMWS-chitosan) were studied in fungal cells and vesicles containing various compositions of fungal lipids. LMWS-chitosan showed strong antifungal activity against various pathogenic yeasts and hyphae-forming fungi but no hemolytic activity or cytotoxicity against mammalian cells. The degree of calcein leakage was assessed on the basis of lipid composition (PC/CH; 10:1, w/w). Our result showing that LMWS-chitosan interacts with liposomes demonstrated that chitosan induces leakage from zwitterionic lipid vesicles. Confocal microscopy revealed that LMWS-chitosan was located in the plasma membrane. Finally, scanning electron microscopy revealed that LMWS-chitosan causes significant morphological changes on fungal surfaces. Its potent antibiotic activity suggests that LMWS-chitosan is an excellent candidate as a lead compound for the development of novel anti-infective agents.

• Mycobiology
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• v.43 no.1
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• pp.87-91
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• 2015

Eighteen endophytic fungi with different colony morphologies were isolated from the roots of Nymphoides peltata growing in the Dalsung wetland. The fungal culture filtrates of the endophytic fungi were treated to Waito-c rice seedling to evaluate their plant growth-promoting activities. Culture filtrate of Y2H0002 fungal strain promoted the growth of the Waito-c rice seedlings. This strain was identified on the basis of sequences of the partial internal transcribed spacer region and the partial beta-tubulin gene. Upon chromatographic analysis of the culture filtrate of Y2H0002 strain, the gibberellins (GAs: $GA_1$, $GA_3$, and $GA_4$) were detected and quantified. Molecular and morphological studies identified the Y2H0002 strain as belonging to Aspergillus clavatus. These results indicated that A. clavatus improves the growth of plants and produces various GAs, and may participate in the growth of plants under diverse environmental conditions.