• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.1
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• pp.62-67
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• 2002

An efficient system of rice microspore culture could contribute to the production of genetically modified rice. The microspores were isolated by mechanical or shed methods. The number of microspores per 100 anthers isolated at uninucleate stage was higher than (or similar to) those at binucleate stage in isolation method with pestle or spatular, but microspore divisions were not easily observed on both stages. On the other hand, pollen division in shed pollen culture was observed more frequently at uninuclear than at binuclear stage. Cold pretreatment at 1$0^{\circ}C$ for 10 days resulted in the best multicellular division to produce microcalli at 12.5% efficiency in shed microspores. Heat shock at 33$^{\circ}C$ for one hour before or after pollen shedding enhanced cell division and callus formation. Out of twelve green regenerants, two were haploids and ten were diploids based on the chromosome analysis of root tips. The size of stoma was 12$^{m}$ m in haploids and 15 ${\mu}{\textrm}{m}$ in diploids determined by scanning electron microscope (SEM).

• Korean Journal of Plant Tissue Culture
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• v.26 no.3
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• pp.143-148
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• 1999

This study was conducted to elucidate the effects of ascorbic acid and dehydroascorbic acid on somatic embryogenesis from the cultured cells of carrot. Ascorbic acid in culture medium merely stimulated the proliferation of non-embryogenic cells but dehydroascorbic acid in medium induced embryogenic cells from non-embryogenic cells accompanying the inhibition of cell proliferation. Ascorbic acid in medium inhibited somatic embryogenesis from embryogenic cells while dehydroascorbic acid in medium enhanced somatic embryogenesis from the cells as well as non-embryogenic cells. This enhancement was limited to globular embryos and the maturation to cotyledonary embryos was inhibited by dehydroascorbic acid treatment. From the above results it is suggested that carrot callus cultures on medium containing dehydroascorbic acid could quickly induce embryogenic cells. In addition after brief culture of embryogenic cells on development medium containing dehydroascorbic there by acid the subculture of the cells to MS basal medium resulted in the high frequency production of somatic embryos.

• Plant Biotechnology Reports
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• v.2 no.4
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• pp.227-231
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• 2008

D-class cyclins play important roles in controlling the cell cycle in development and in response to external signals by forming the regulatory subunit of cyclin-dependent kinase (CDK) complexes. To evaluate the effects of D-class cyclins in transgenic rice plants, Arabidopsis cyclin D2 gene (CycD2) was linked to the maize ubiquitin1 promoter (Ubi1) and introduced into rice by the Agrobacterium-mediated transformation method. Genomic deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and Western blot hybridizations of the Ubi1:-CycD2 plants revealed copy number of transgene and its increased expression in leaf and callus cells at messenger RNA (mRNA) and/or protein levels. The H1 kinase assay using the immunoprecipitates of protein extracts from the Ubi1:CycD2 plants and nontransgenic controls demonstrated that the introduced Arabidopsis CycD2 forms a functional CycD2/CDK complex with an unidentified CDK of rice. Shoot and root growth was enhanced in the Ubi1:CycD2 seedlings compared with nontransgenic controls, together, suggesting that Arabidopsis cyclin D2 interacts with a rice cyclin-dependent kinase, consequently enhancing seedling growth.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.4
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• pp.356-361
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• 2006

The present study was conducted to determine plant growth and physiological responses of corn, barnyardgrass, and soybean to ALA (5-aminolevulinic acid). ALA effect on early seedling growth of test plants was greatly concentration dependant, suggesting that it inhibits at higher concentrations. No significant difference in herbicidal activity of two types of ALA on plant height and weight of test plants was observed. Barnyardgrass was the most sensitive to ALA and followed by corn and soybean, indicating that both crop plants were less affected by ALA concentration as well as different growth stages than barnyardgrass. Greatly reduced chlorophyll contents from leaves of three plant species were observed with increasing of ALA concentration. Compared with untreated controls, higher amounts of three tetrapyrroles were detected from three crop plants, indicating more accumulation in ALA-treated plants. The differential selectivity among plant species would be explained with the differences in tetrapyrrole accumulating capabilities, the susceptibility of various greening groups of plant species to the accumulation of various tetrapyrroles, and their metabolism in various plant tissues. The results indicate that negative biological potential of ALA exhibited differently on plant species, and that the photodynamic herbicidal activity against susceptible plants highly correlated with the extent of tetrapyrrole accumulation by the species.

• Korean Journal of Plant Resources
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• v.19 no.3
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• pp.405-410
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• 2006

A series of aqueous or methanol extracts from four different Korean salad plants were assayed to determine their allelopathy and antioxidant activity. The extracts applied on filter paper in a Petri-dish bioassay significantly inhibited root growth of against alfalfa (Medicago sativa) seedlings. Leaf extracts from 40 g dry tissue $L^{-1}$ of Aster yomena was most phytotoxic to alfalfa root growth, and followed by that of Cirsium japonicum, Taraxacum officinale, and Ixeris dentate. Methanol extracts of plants dose-dependently increased DPPH free radical scavenging activity in vitro. Antioxidant activity of methanol extracts from the same plant species was investigated, and the result showed high DPPH free radical scavenging activity in Cirsium japonicum, Aster yomena, and Ixeris dentate, however, in Taraxacum officinale was least activity. By means of HPLC analysis, chlorogenic acid, p-coumaric acid, and total phenolics with 7.68, 17.47 and 18.64 mg, $100g^{-1}$, respectively, showed the highest amounts in methanol extracts from Cirsium japonicum leaves. These results suggest that Compositae salad plants contain water-soluble substances with allelopathic potential as well as antioxidant activity.

• Journal of Ginseng Research
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• v.35 no.1
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• pp.21-30
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• 2011

Panax ginseng root has been used as a major source of ginsenoside throughout the history of oriental medicine. In recent years, scientists have found that all of its biomass, including embryogenic calli and flower buds can contain similar active ingredients with pharmacological functions. In this study, transcriptome analyses were used to identify different gene expressions from embryogenic calli and fl ower buds. In total, 6,226 expressed sequence tags (ESTs) were obtained from cDNA libraries of P. ginseng. Insilico analysis was conducted to annotate the putative sequences using gene ontology functional analysis, Kyoto Encyclopedia of Genes and Genomes orthology biochemical analysis, and interproscan protein functional domain analysis. From the obtained results, genes responsible for growth, pathogenicity, pigments, ginsenoside pathway, and development were discussed. Almost 83.3% of the EST sequence was annotated using one-dimensional insilico analysis.

• Korean Journal of Weed Science
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• v.15 no.2
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• pp.160-165
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• 1995

Anthocyanin formation in callus cultures using Populus alba ${\times}$ Populus glandulosa was evaluated on basal MS medium supplemented with various levels of growth regulators, sucrose and nitrate concentrations. The highest yield of anthocyanin from cultured cells was produced under 5% sucrose, 1/8 strength of nitrate(12.5% of basic concentration) and combination of 1.0 mg/l IAA with 2 mg/l BAP, respectively. The high anthocyanin producing cell line no. 11 was selected among 15 cell lines, showing over 80% cells contained anthocyanin producing cells. From these cells, the highly productive red protoplast was isolated and the highest protoplast yield, $6.7{\times}10^6$ was obtained in enzyme combination IV which is composed of 2.0% cellulase, 0.5% macerozyme and 0.1% pectolyase.

• Composites Research
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• v.20 no.5
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• pp.7-12
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• 2007

This paper aims to enhance the efficiency of bone fracture healing with bone plate made of fiber reinforced composite materials. The composite bone plate was designed as the same dimension and shape as the existing stainless steel bone plate. To find out the appropriate stacking sequence of the composite bone plate the variations of strain distributions were calculated using FE analysis when the bone plates were applied to the fracture site. From the analysis result it was found that the composite bone plate whose Young's modulus is lower than that of metal bone plate gave more uniform strain distribution and provided appropriate condition for callus formation and its development.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.spc1
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• pp.233-236
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• 2006

This study was conducted to investigate somatic embryogenesis capacity using callus derived from bud meristems in sweetpotato. Shoot apical meristem explants $(height:150{\mu}m;base:\;350{\mu}m)$were cultured on MS medium supplemented with 1 mg/L 2/4-D. Embryogenic callus were observed in five cultivars when their shoot apices were cultured on MS medium supplements with 1 mg/L 2,4-D. After 6 weeks of culture, greater than 80% of the survived explants produced embryogenic calli and the calli gave rise to somatic embryos at frequencies of 72% (Yulmi), 60% (Shinhwangmi), 78% (Geonmi), 70% (KoKei 14), 40% (Sinjami). The regenerated plants developed into whole plantlets after they were transferred onto the fresh hormon-free MS medium of 74% (Yulmi), 82% (Shinhwangmi), 86% (Geonmi), 74% (Kokei 14), 41% (Sinjami) respectively.

• Korean Journal of Weed Science
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• v.8 no.2
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• pp.182-186
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• 1988

This study was conducted to level up the tolerance of tobacco plant against bialaphos herbicide through tissue culture. The relatively good shoot regeneration from the subcultured calli treated with bialaphos at 0.5 ppm was observed in old the tobacco varieties tested such as NC 82, BY 4 and KA 101. However, at the treatment of bialaphos 1.0 ppm, shoot regeneration was only made in KA 101 variety, showing better regeneration than that of untreated one, When these shoots were transfered to the medium containing of bialaphos 10.0 ppm, the percentage of living shoots (i.e. tolerant plant) was very low, showing 2.43% in NC 82, 2.76% in KA 101 and 0.78% BY 4. Calli were induced and multiplied from leaf petiole of the above tolerant plants even under 2.5ppm of bialaphos, showing an average of 9% in NC 82 and 16% in KA 101 as compared with the untreated control. No calli were induced from tolerant plants as bialaphos concentration increased up to 5.0 ppm. Direct shooting from leaves of the above tolerant plants, that is selected at 10.0ppm of bialaphos treatment, was observed even under 10.0ppm of bialaphos treatment both in NC 82 and in KA 101 varieties, indicating that tolerance of tobacco plants against bialaphos can be greatly increased.