• The Plant Pathology Journal
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• v.21 no.2
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• pp.87-92
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• 2005

The structural differences between healthy and diseasedpanicle necks caused by Pyricularia oryzae were observed using electron-microscope. In the diseased panicle neck, the infection hyphae of the rice blast pathogen grew through the sclerenchymatous fiber tissue and reached to the central internal lacuna. Since the pathogen grew through the sclerenchymatous fiber tissues, the vascular bundle composed with xylem and phloem had been destroyed and finally the nutrients from the leaf and stem were not able to be transported into the grains. Infection of panicle base by the blast pathogen until 20 days after heading caused more than 50% of yield loss in both Jinmibyeo and Chucheongbyeo. There was a positive correlation between incidence of the panicle blast and rice yield losses. The regression equations between incidence of the panicle blast and yield losses were y= -3.61+496.7 ($R^2$=0.70) in Jinmibyeoand y=-3.93+520.2 ($R^2$=0.82) in Juanbyeo. The panicleblast caused deterioration of grain quality. Healthy grain rate was reduced by increase of panicle blast infection.

• Journal of Korean Society of Forest Science
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• v.85 no.3
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• pp.343-346
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• 1996

The cultured stain fungus isolated firstly from discolored wood of Pinus rigida was inoculated on wood blocks to investigate the invading pathway of the fungus. The inoculated fungus rapidly colonized in the ray parenchyma and moved radially along them. In process of time the fungus penetrated tracheids where it started to move into vertical direction. After 90 days the fungus colonized all over the wood tissue, therefore some cell lumens were filled with full of hyphae. In addition methanol extracts did not affect the invading pathway of the stain fungus.

• The Plant Pathology Journal
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• v.33 no.1
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• pp.80-86
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• 2017

One of the major problems in strawberry production is difficulty in diagnosis of anthracnose caused by Colletotrichum acutatum or Glomerella cingulata in latent infection stage. We here developed a diagnostic tool for the latent infection consisting of initial culturing of fungi, DNA extraction, synthesis of PCR-amplified probes and microtube hybridization (MTH) using a macroarray. The initial culturing step is convenient to lure the fungi out of the plant tissues, and to extract PCR-inhibitor-free DNA directly from fungal hyphae. For specific detection of the fungi, PCR primers were designed to amplify the fungal MAT1-2 gene. The subsequent MTH step using the PCR products as probes can replace the laborious electrophoresis step providing us sequence information and high-throughput screening. Using this method, we have conducted a survey for a few thousands nursery plants every year for three consecutive years, and finally succeeded in eliminating latent infection in the third year of challenge.

• Mycobiology
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• v.29 no.2
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• pp.110-112
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• 2001

A black scab was observed on strawberry(Fragaria ananassa) in plastic film houses around Jinju area during the winter of 2000. The disease started from leaves then moved to calyx and runner. At the beginning, the infected area started with small dark brown spots then gradually expanded. The pathogenic fungus was purely isolated from the diseased leaves, calyx and runner. The fungus was inoculated to test Koch's postulates and proved to be the causal agent of the disease. The isolated fungus grew readily on potato dextrose agar, forming dark green to dark gray colonies. The optimum temperature for mycelial growth was about $25^{\circ}C$. The diameter of growing hyphae was $3.8{\sim}5.6{\mu}m$. Conidia were ellipsoidal, ovoid or subspherical, mostly one-celled but occasionally septate. The size of conidia were $4.1{\sim}11.7{\times}3.8{\sim}5.3$ 1-cell, $9.3{\sim}18.8{\times}4.0{\sim}7.4{\mu}m$ 2-cell and formed in long branched chains on the erected conidiophores which were dark brown and variable in length between $28.8{\sim}236.2{\times}3.0{\sim}6.2{\mu}m$ in size. The fungus was identified as Cladosporium herbarum on the basis of its morphological characteristics. The black scab disease of strawberry caused by C. herbarum has not been reported in Korea previously.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.107.1-107
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• 2003

The fermentation process and subsequent processing determine the efficacy of a bioherbicide propagule. Large batches of biomass of the mycoherbicide agent for white clover, Sclerotium sp.(BWC98-105) was produced in simple liquid fermentator in 5 gallons vessels(Model No. 8087, Dabo Inc., Korea) with oxygen supply(DPH16000, FineTech Inc., Korea) simulating industrial conditions by utilizing commercially available, inexpensive ingredients (10 ％ rice bran), The maximum biomass yield of Sclerotium sp.(BWC98-105) was obtained after 5 days of air pumped incubation at room temperature condition(22-28$^{\circ}C$). By using this simple facility, it could get fragmented or proliferated greatly and attained maximum mycelia biomass. The biomass of mycoherbicide agent consisted of hyphae devoid of spores. Biomass mycelia of the fungus 99％ survival at room temperature after 2 me. A thorough understanding of the effects of fermentation and formulation on viability and virulence is required to guide these processes. After an economical yield level of bioherbicide propagule has been achieved in a fermentation process, formulation becomes a critical factor which influences product efficacy. Because the fermentation must be stopped at a point when virulence/viability are optimum, the live bioherbicide propagule must be stabilized, formulated, and packaged.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.19-20
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• 2003

Helicobasidium mompa Tanaka and Resellinia necatrix Prillieux cause violet root rot and white root rot of various crops, respectively. Intensive cultural practices, such as the use of dwarf stock, glasshouse cultivation, etc., predispose plants to the diseases. The diseases can be controlled only by biennial drench of 50100L of chemicals for each tree. Biocontrol with soil microorganisms proved ineffective under field conditions. Long-term control may be hampered by the perennial growth of hosts and by the difficulty in the establishment of antagonists in soil. Crop rotation or soil amendment is not applicable, either. Fungal viruses with dsRNA genome (Buck 1986) are promising against root diseases of fruit trees since they exist within the cytoplasm of fungal hyphae and need no effort to help them persist in the field. The viruses are considered to spread though the network of fungal mycelia in the soil once they enter the fungal cytoplasm. Here, we present preliminary results from a project to control the root diseases of fruit trees with dsRNA.(중략)

• Korean Journal Plant Pathology
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• v.11 no.3
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• pp.278-281
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• 1995

An isolate of Rhizoctonia solani AG 2-2(IV) from zoysiagrass was examined on development of its teleomorph by the modified soil-on-agar culture method. The most effective growth medium for sporulation was Czapek's 1/2 agar medium added with yeast extract and peptone. The characters of teleomorph of R. solani AG 2-2 (IV) are as follows. Hymenia developed on soil surface after the development of vegetative hyphae. Basidia were barrel-shaped, short clavate or obovate and were 11.4~17.9$\times$7.1~11.4 ${\mu}{\textrm}{m}$ (mean : 15.1$\times$9.0 ${\mu}{\textrm}{m}$) in size. Sterigmata were horn-shaped and slightly bent to the inner side and 4.3~18.6 ${\mu}{\textrm}{m}$ (mean : 10.3 ${\mu}{\textrm}{m}$) in size. Two to four sterigmata developed on each basidium. Basidiospores were obovate, ellipsoid to oblong-ellipsoid, hyaline, smooth, thin walled, with an apiculus, and 3.6~10.4$\times$2.9~5.7 ${\mu}{\textrm}{m}$ (mean : 7.8$\times$4.4 ${\mu}{\textrm}{m}$) in size.

• Applied Biological Chemistry
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• v.35 no.3
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• pp.191-195
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• 1992

In order to elucidate the plant-microorganism relationship, we purified an ethylene-inducible, basic 30 KD endochitinase from bean leaves and studied its antifungal activity by a hyphal extension-inhibition assay. The purified chitinase was effective in the inhibition of hyphal growth of Aspergillus fumigatus, Botrytis cinerea, Fusarium oxysporum, Rhizoctonia solani, while microbial chitinases of Serratia marcescens and Streptomyces griceus, egg white lysozyme and papya protease didn't affect hyphal growth of the fungi. The chitinase degraded the cell walls of Micrococcus lysodeikticus, suggesting the lysozyme activity of the chitinase. We discussed the implication of the bifunctional chitinase/lysozyme activities of the protein with hydrolysis of chitin in the rapidly extending hyphae of the fungi.

• Journal of Veterinary Clinics
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• v.8 no.1
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• pp.53-57
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• 1991

Opportunistic mycotic infection of mammary gland due to Candida tropicalis is described in a 7-year-old Holstein Friesian cow with a history of prologned use of antibiotics and corticosteroids. C. tropicalis was repeatedly isolated from the mastitic milk on simplified sunflower seed medium at 30$^{\circ}C$. The pathogen was directly detected in the infected milk by 'PHOL' technique. Microscopic examination of Gram stained smears of milk sediment revealed numerous yeast cells and hyphae morphologically consistent with Candida spp. In vitro drug sensitivity test indicated that C. tropicalis was sensitive to nystatin. Chemotherapy with intramammary infusion of nystatin was successful as evidenced by clinical and mycological observations. It emphasizes the growing significance of Candida spp. and other opportunistic fungal pathogens in Veterinary medicine.

• The Plant Pathology Journal
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• v.18 no.2
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• pp.57-62
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• 2002

In vivo expression technology (IVET) has been developed to study bacterial gene expression in Salmonella typhimurium during host infection. The expression of selected genes by IVET has been elevated in vivo but not in vitro. The selected genes turned out to be important for bacterial virulence and/or pathogenicity. IVET depends on a synthetic operon with a promoterless transcriptional fusion between a selection marker gene and a reporter gene. The IVET approach has been successfully adapted in other bacterial pathogens and plant-associated bacteria using different selection markers. Pseudomonas putida suppresses citrus root rot caused by Phytophthora parasitica and enhances citrus seedling growth. The WET strategy was adapted based on a transcriptional fusion, pyrBC'-lacZ, in P. putida to study the bacterial traits important far biocontrol activities. Several genes appeared to be induced on P. parasitica hyphae and were found to be related with metabolism and regulation of gene expression. It is likely that the biocontrol strain took a metabolic advantage from the plant pathogenic fungus and then suppressed citrus root rot effectively. The result was parallel with those from the adaptation of IVET in P. fluorescens, a plant growth promoting rhizobacteria (PGPR). Interestingly, genes encoding components for type III secretion system have been identified as rhizosphere-induced genes in the PGPR strain. The type III secretion system may play a certain role during interaction with its counterpart plants. Application of IVET has been demonstrated in a wide range of bacteria. It is an important strategy to genetically understand complicated bacterial traits in the environment.