• Proceedings of the Plant Resources Society of Korea Conference
• /
• 2003.10b
• /
• pp.47-47
• /
• 2003

Plant growth promoting rhizobacteria (PGPR) have been shown to suppress phytopthora blight. This suppression has been related to both microbial antagonism and induced resistance. The PGPR isolates were screened by dual culture plate method and most of the isolates were showed varyinglevels of antagonism. Among the PGPR isolates pyoverdin, pyochelin and salicylic acid producing strains showed the maximum inhibition of mycelial growth of Phytophthora capsici and increased plant growth promotion in red pepper. PGPR isolatesfurther analysed for its ability to induce production of defence related enzymes and chemicals. The activities such as Phenyle alanin ammonia lyase (PAL), Peroxidase (PO), Polyphenol oxidase (PPO) and accumulation of phenolics were observed in PGPR pretreated red pepper plants challenged with Phytophthora capsici. The present study shows that an addition of direct antagonism and plant growth promotion, induction of defense related enzymes involved to enhance resistance against invasion of P. capsici in red pepper.

• Proceedings of the Korean Society of Plant Pathology Conference
• /
• 2005.10a
• /
• pp.15-20
• /
• 2005

Locations of silicon accumulation in rice leaves and its possible association with resistance to rice blast were investigated by analytical electron microscopy and atomic force microscopy. A blast-susceptible cultivar, Jinmi, and partially resistant cultivars, Hwaseong and Suwon345, were grown under a hydroponic culture system with modified Yoshida's nutrient solution. Electron-dense silicon layers were frequently found beneath the cuticle in epidermal cell walls of silicon-treated plants. Increasing levels of silicon were detected in the outer regions of epidermal cell walls. Silicon was present mainly in epidermal cell walls, middle lamella, and Intercellular spaces within subepidermal tissues. Furthermore, silicon was prevalent throughout the leaf surface with relatively small deposition on stomatal guard cells in silicon-treated plants. Force-distance curve measurements revealed relative hardness and smaller adhesion force in silicon-treated plants (18.65 uN) than control plants (28.39 uN). Moreover, force modulation microscopy showed higher mean height values of elastic Images In silicon-treated plants(1.26 V) than in control plants (0.44 V), implying the increased leaf hardness by silicon treatment. These results strongly suggest that silicon-induced cell wall fortification of rice leaves may be closely associated with enhanced host resistance to blast.

• The Plant Pathology Journal
• /
• v.17 no.3
• /
• pp.128-140
• /
• 2001

Infection of pepper leaves by Colletotrichum cocodes at the two- and eight-leaf stages caused susceptible and resistant lesions 96 h after inoculation, respectively. At the two-leaf stage, progressive symptom development occurred on the infected leaves. In contrast, localized necrotic spots were characteristic symptoms at the eight-leaf stage. Infected leaves at the two-leaf stage exhibited cell death accompanied by the accumulation of autofluorescent compounds. At the eight-leaf stage, pepper leaves infected by the anthracnose fungus displayed localized autofluorescence from the symptoms. Infection of pepper leaves by C. cocodes at the two-leaf stage resulted in its rapidand massive colonization of all the leaf tissues including the vascular tissue, together with cytoplasmic collapse, distortion of chloroplasts, and disruption of host cell walls. However, penetration of C. cocodes was very limited in the older leaf tissues of pepper plants at the eight-leaf stage. Fungal hyphae grew only in the intramural spaces of the epidermal cell walls at this stage. Occlusion of amorphous material in xylem vessels, aggregation of fibrillar material in inter-cellular spaces, and deposition of protein bodies were found as resistance responses to C. cocodes.

• Journal of the Korean Society for Heat Treatment
• /
• v.7 no.3
• /
• pp.155-159
• /
• 1994

As Cr-Mo-V steels have excellent mechanical and creep properties at elevated temperatures, they are extensively used in power plants. However, the steam turbine components are supposed to have suffered material degradation during long-term service at elevated tenperatures. Many efforts have been made to assess the safety and residual life of these components by means of non-destructive methods such as plastic replication, hardness and electric resistance techniques. Recently, a parameter correlating hardness changes during long-term heating to those during creep was introduced and it was named 'G parameter'. The electric resistivity as well as hardness are affected by damage accumulation, but there have been no efforts to correlate G parameter to resistivity changes. In this study, relationship between G parameter and changes in electric resistivity was investigated using artificially aged Cr-Mo-V steel. It is well understood that G parameter can be applied to electric: resistance techmique.

• Transactions of Materials Processing
• /
• v.14 no.6 s.78
• /
• pp.502-508
• /
• 2005

Hypereutectic Al-Si alloys have been regarded attractive for automotive and aerospace application, due to high specific strength, good wear resistance, high thermal stability, low thermal expansion coefficient and good creep resistance. Spray casting of hypereutectic Al-Si alloy has been reported to provide distinct advantages over ingot metallurgy (IM) or rapid solidification/powder metallurgy (RS/PM) process in terms of microstructure refinement. In this study, hypereutectic Al-25Si-2.0Cu-1.0Mg alloy was prepared by OSPREY spray casting process. The change of strain rate sensitivity and Creep transition were analyzed by using the load relaxation test and constant creep test. High temperature deformation behavior of the hypereutectic Al-Si alloy has been investigated by applying the internal variable theory proposed by Chang et al. Especially, the creep resistance of spray casted hypereutectic Al-Si alloy can be enhanced considerably by the accumulation of prestrain.

• Korean journal of applied entomology
• /
• v.21 no.3 s.52
• /
• pp.128-132
• /
• 1982

Starch contents in healthy and powdery mildew-infected spring barley leaves at first and fifth leaf stages were measured at different intervals after inoculation. Different patterns of starch accumulation in the susceptible cultivar Peruvian and the adult plant resistant cultivar Asse were found in infected first and fifth leaves. At the early phase of infection, the amount of starch in infected first leaves was slightly changed in both cultivars. During colony development and sporulation, the decrease in starch content was .more marked in the susceptible Peruvian, whereas the amounts of starch in the adult plant resistant Asse increased during colony development and then decreased sharply before and after sporulation. In heavily infected first leaves, the susceptible cultivar Peruvian showed a drastic decrease in starch content. In the adult plant resistant cultivar Asse, the higher amount of starch retained in these infected leaves, regardless of infection intensity. The regulation of starch accumulation in mildewed barley plants at different leaf stages was discussed in relation to adult plant resistance of spring barley.

• Weed & Turfgrass Science
• /
• v.1 no.4
• /
• pp.50-56
• /
• 2012

The objectives of this research were to quantify resistance levels of transgenic rice expressing the bar gene to glutamine synthetase (GS)-inhibiting, and methionine sulfoximine and photosynthesis-inhibiting herbicide, paraquat, and compare the ammonium accumulation, chilling injury, and yield between transgenic and non-transgenic rice. The transgenic rice lines were 45-96-fold more resistant to glufosinate-ammonium than non-transgenic rice. The transgenic rice lines were also 18-fold more resistant to methionine sulfoximine, but was not resistant to paraquat, which has different target site. Glufosinate-ammonium increased the ammonium accumulation in leaves of non-transgenic rice plants, but had minimal or no effect on leaves of transgenic lines. The transgenic lines except for 258, 411, 607 and 608 were more susceptible during chilling and recovery than non-transgenic rice plants. The yield of transgenic lines 142, 144, 258 and 608 was similar or higher than that of non-transgenic rice in pot conditions.

• Journal of Plant Biotechnology
• /
• v.33 no.1
• /
• pp.57-62
• /
• 2006

Several methods for determining the response of corn to glyphosate were investigated to provide a fast and reliable method for identifying glyphosate-resistant corn in vivo. Two bioassays were developed. One assay is named 'whole plant / leaf growth assay', in which the herbicide glyphosate is applied on the upper part of 3rd leaf and the growth of herbicide-untreated 4th leaf is measured at 3 day after treatment. in this assay, the leaf growth of conventional corn was inhibited in a dose dependent from 50 to $1600{\mu}g/mL$ of glyphosate and growth inhibition at $1600{\mu}g/mL$ was 55% of untreated control. The assay has the potential to be used especially in the case that the primary cause of glyphosate resistance is related with a reduction of the herbicide translocation. Another assay is named 'leaf segment / shikimate accumulation assay', in which the four excised leaf segments ($4{\times}4mm$) are placed in each well of a 48-well microtiter plate containing $200{\mu}L$ test solution and the amount of shikimate is determined after incubation for 24 h in continuous light at $25^{\circ}C$. In this assay, 0.33% sucrose added to basic test solution enhanced a shikimate accumulation by 3 to 4 times and the shikimate accumulation was linearly occurred from 2 to $8{\mu}g/mL$ of glyphosate, showing an improved response to the method described by Shaner et al. (2005). The leaf segment / shikimate accumulation assay is simple and robust and has the potential to be used as a high throughput assay in the case that the primary cause of glyphosate resistance is related with EPSPS, target site of the herbicide. Taken together, these two assays would be highly useful to initially select the lines obtained after transformation, to investigate the migration of glyphosate-resistant gene into other weeds and to detect a weedy glyphosate-resistant corn in field.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.27 no.1
• /
• pp.60-65
• /
• 1982

In order to observe the degree and response of drought-resistance and its physiological mechanism in barley and wheat seedling stage, 5 species (16 cultivars) were tested for the changes of nitrate reductase and protease activity and the accumulation of free proline, by being subjected to water stress by withholding watering for 8 days at 10 days (at the 3rd leaf stage) after emergence and by imposing water stress to the excised first leaf by polyethyleneglycol solution (osmotic potential, -20 bars) for 48 hours. The average rate of decrease of all cultivars was 42% in nitrate reductase activity and 73% in protease activity. But proline content in water stress was increased 10 folds more than that of control. The decrease4 rate of nitrate reductase activity in 5 species was in the order of wheat < rye < covered barley < naked barley < two-row barley: wheat being the lowest. The decreased rate of protease activity in 5 species was in the order of wheat > rye > two-row barley > covered barley > naked barley: wheat being the" heighest. The accumulated amount of free proline in 5 species by water stress was in the order of wheat > covered barley > rye > naked barley > two-row barley. And the increased ratio (folds) of free proline of water stress to control was in the order of rye(13) > wheat. covered barley(11) > naked barley(99) > two-row barley(7): rye being the highest. In terms of the enzymatic activity and the physiotically adaptive metabolism during the processing leading to drought-resistance, the degree of drought-resistance of 5 species to water stress at seedling stage was shown to be in the order of wheat > rye > covered barley > naked barley > two-row barley.

• The Journal of Korean Medicine
• /
• v.38 no.2
• /
• pp.53-60
• /
• 2017

Objectives: Beakdugu-tang (BDGT) consists of three medicinal herbs, and this prescription has long been used in treatment of various digestant problem in Korea. In this study, we designed to clarify mechanisms by which Korean traditional digestive medicine, BDGT, may exert anti-hepatic steatosis effects via improved insulin resistance cell model in human hepatocellular carcinoma (HepG2) and monocyte (THP-1). Materials and methods: The preparation of BDGT and constituents were extracted with 70% ethanol. HepG2 and THP-1 were treated with different concentrations of BDGT and constituents in the presence and absence of stimulants such as free fatty acids (FFAs) and oxidized low-density lipoprotein (ox-LDL), respectively. Results: The BDGT and its constituents inhibited the FFAs-stimulated lipid accumulation in HepG2 cells. Ethanol extracts of Amomum cardamomum (ACE) improved the ox-LDL induced insulin resistance in THP-1 cells. Also, treatment of monocytic cells with ACE increased anti-hepatic steatosis related gene levels including ABCA, ABCG and SR-B1. Conclusion: The results suggest that the ethanol extract of BDGT and its constituents potently inhibit the FFAs- and ox-LDL induced liver steatosis via improved insulin resistance.