• Journal of Environmental Science International
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• v.1 no.2
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• pp.87-91
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• 1992

Leaf discs were excised from spinach leaves (Spinaia oleracea L.) and floated in phosphate buffer (pH 6.8) containing paraquat solutions (0, 0.1, 1.0, 10, 20, 50 and 100 ppm), and incubated in the growth chamber under 5, 500 lux illumination at $25^{\circ}C$ for 24 hr. Treatment with paraquat caused the formation of malondialdehyde (MDA), an indicator of lipid peroxidation in leaf discs. When 1.0, 10, 20, 50 and 100 ppm of paraquat solutions were applied to leaf discs, the contents of MDA were increased by 63, n6, 100, 140 and 150% of the level without paraquat treatment, respectively. 1.0, 10, 20, 50 and 100 ppm of paraquat treatments reduced the amounts of ascorbic acid in leaf discs by 23, 35, 38, 42 and 56% of the level without paraquat treatment respectively. Activities of superoxide dismutase (SOD) in leaf discs of 1.0, 10, 20, 50 and 100 ppm of paraquat treatments were decreased by 23, 42, 48, 61 and 70% of the level of SOD in non-treated group, respectively. The results suggest that paraquat may cause peroxidation of membrane lipid in spinach leaves as a result of paraquat-induced destruction of physiological defense against oxygen phytotoxicity.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.1 no.2
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• pp.87-91
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• 1997

Leaf discs were excised from spinach leaves (Spinacia oleracea L.) and floated in phosphate buffer (pH 6.8) containing paraquat solutions (0, 0.1, 1.0, 10, 20, 50 and 100 ppm), and incubated in the growth chamber under 5,500 lux illumination at $25^{\circ}C$ for 24 hr. Treatment with paraquat caused the formation of malondialdehyde (MDA), an indicator of lipid peroxidation in leaf discs. When 1.0, 10, 20, 50 and 100 ppm of paraquat solutions were applied to leaf discs, the contents of MDA were increased by 63, 86, 100, 140 and $150\%$ of the level without paraquat treatment respectively. 1.0, 10, 20, 50 and 100 ppm of paraquat treatments reduced the amounts of ascorbic acid in leaf discs by 23, 35, 38, 42 and $56\%$ of the level without paraquat treatment, respectively. Activities of superoxide dismutase (SOD) in leaf discs of 1.0, 10, 20, 50 and 100 ppm of paraquat treatments were decreased by 23, 42, 48, 61 and $70\%$ of the level of SOD in non-treated group, respectively. The results suggest that paraquat may cause peroxidation of membrane lipid in spinach leaves as a result of paraquat-induced destruction of physiological defense against oxygen phytotoxicity.

• Korean Journal of Medicinal Crop Science
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• v.10 no.4
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• pp.259-262
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• 2002

The efficiency of regeneration of callus and explants from leaf and stem disks of Epimedium koreanum was examined on the MS media containing 2,4-D, NAA, Kinetin, BA and TDZ. Calli were formed on the 2mg/l 2,4-D media at the rate of 32% from leaf discs and 52% from stems. No callus was produced on the media which are containing BA or TDZ alone. The combination of 2,4-D and BA showed the effect on the formation of callus. The combination of 2mg/l 2,4-D and 0.lmg/l BA in the MS media had produced the highest percentage of callus formation, 50% from leaf discs and 40% from stems, respectively. The combination of 2mg/l 2,4-D and 1mg/1 BA in the MS media had affected the formation of callus in the rate of 40% from leaf discs and 25% from stems. The combined plant growth regulators of 2,4-D and BA increased the formation of calli from leaf discs, but single treatment of 2,4-D showed the highest callus formation from stems. Multiple shoots from leaf discs were formed on the media containing NAA, BA, kinetin, and TDZ. The highest number of multiple shoots were obtained 0.1mg/l NAA combined with 1mg/l kinetin. As a result, leaf discs or stems can be used for the mass propagation of Epimedium koreanum, but stem elongation of shoots from calli was not easy.

• Journal of Plant Biology
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• v.31 no.2
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• pp.155-164
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• 1988

The rapid senescence of detached Chinese cabbage leaf discs in darkness is first manifested by a sharp rise in malondialdehyde content (indicated by distruption of membrane structure), then by a rise in peroxidase activity and a decrease in catalase activity, and ultimately by chlorophyll degradation. These changes in parameters besides the catalase activity during senescence were delayed by application of spermidine. Especially, 10-4M spermidine almost completely arrested chlorophyll degradation after incubaton over 5 days. Spermidine reduced the amount of ethylene produced by senescing leaf discs. Additionally, it also reduced IAA-induced ethylene production. Calcium ion (1mM, 10mM) supplied together with the spermidine diminished the spermidine action, indicating probable involvement of an initial ionic attachment mechanism. These results suggest that spermidine can be used as an anti-senescence agent for plants and that this agent may stabilize membrane structure through interaction with the negatively charged loci on the membrane and exert the influence during senescence.

• Korean Journal of Plant Resources
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• v.12 no.4
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• pp.253-259
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• 1999

In this study, three simple methods were established to confirm the transgenic potato plants. The leaf disc was used in the first method. After leaf discs of transgenic and non-transgenic potato were transfered into the liquid MS medium with bialaphos 5mg/l, 25 days, the chlorosis occurred in the non-transgenic leaf discs while it could not find in the transgenic leaf discs, In the second method, shoot tips of potato were transferred into MS medium supplemented with 0.5mg/l bialaphos and 0.6% agar. After 7-10 days, a lot of roots developed from the transgenic shoot tip, but the non-transgenic shoot tip was dead. The third method was using chlorophyll contents. Leaf discs were transferred into the liquid MS medium with bialaphos 0.5 mg/l. After 15 days, the content of chlorophyll A in transgenic plant was at least 2.5 times higher than in non-transgenic plant. In addition, the PAT enzyme activity were detected in the transgenic potato, but not detected in normal potato.

• Plant Resources
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• v.4 no.3
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• pp.111-120
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• 2001

The efficiency of in vitro regeneration of four clones of Populus euramericana, Canada blanc, Eugenii, I-45/51, and Wisconsin #5, was examined. Cytokinins and the combinations with auxins affected the rate of regeneration from the explants of root segments, stem internodes, and leaf discs. Overall, BA and the combination with auxins were effective in root segments and leaf discs of the Canada blanc clone, whereas zeatin and the combination with auxins were important in stem internodes of the Wisconsin #5 clone. The highest number of shoots averaging 17.6 $\pm$ 0.47 from root segments in the Canada blanc clone,18.2 $\pm$ 3.0 from stem internodes in the Wisconsin #5 clone, and 17.8 $\pm$ 1.92 from leaf discs in the Canada blanc clone were obtained with 2.0 mg/1 BA, 2.0 mg/l zeatin combined with 0.2 mg/l IAA, and 0.5 mg/l BA combined with 0.05 mg/l 2,4-D, respectively. In particular, the addition of 2,4-D into cytokinin medium promoted shoot proliferation.

• Journal of Plant Biology
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• v.36 no.4
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• pp.383-389
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• 1993

The effects of light and $CO_2$ on the electrophysiological characteristics of guard cells in the intact leaf and in the detached epidermis have been investigated. Guard cells in intact leaves showed the membrane hyperpolarization in response to light. The biggest induced change of the membrane potential difference (PD) in the guard cells of the intact leaf was 13 m V by light and 42 mV by $CO_2$ in Commelina communis. Similar results were obtained with Tradescantia virginiana. However, there were no changes of membrane PD in detached epidermis. In order to determine the influence of the mesophyll on the changes of membrane PD, infiltration of the mesophyll cells with photosynthetic inhibitors was performed. In CCCP infiltrated leaf discs the guard cell membrane was depolarized slightly by red-light and hyperpolarized by $CO_2$, but in leaf discs infiltrated with DCCD and DCMU the guard cell membrane was hyperpolrized by both red-light and $CO_2$ as the control leaf discs. In azide infiltrated leaf discs the guard cell membrane showed no response to light and there was a much reduced membrane hyperpolarization by $CO_2$ compared to other responses. It was likely that azide caused leaf damage and the activity of cell metabolism was decreased greatly, resulting in small membrane PD changes by $CO_2$ and no changes by redlight. Therefore, it can be suggested that red light was sensed by the mesophyll and the light induced guard cell membrane hyperpolarization was related to energy produced by cyclic-photophosphorylation, but ${CO_2}-induced$ guard cell membrane hyperpolarization was not related to photosynthesis. Alkalisation of the vacuole was observed when the intact leaf was exposed to $CO_2$, indicating that membrane hyperpolarization was mainly the result of proton efflux.efflux.

• Korean Journal of Medicinal Crop Science
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• v.13 no.6
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• pp.273-277
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• 2005

Adventitious shoots were directly induced from leaf explants of R. glutinosa, an important medicinal plant. Proliferating shoot cultures were obtained by culturing leaf discs on Murashige and Skoog(MS) medium alone or combination with auxins and cytokinins. MS medium supplemented with 1 $mg/{\ell}\;BA\;and\;2\;mg/{\ell}$ IAA was the most effective, providing high shoot bud formation frequency without formation of intervening callus. The effect of leaf age on adventitious shoot formation was also investigated. The maximum shoot bud production (93.4%) was achived using 3rd leaf from apex of 6 weeks old plantlets after seed germination. Plantlet were rooted on an half-strength MS (1/2MS) medium containing 0.1 $mg/{\ell}\;IBA$. This prtocol is useful for clonal propagation and Agrobacterium-mediated transforamtion in R. glutinosa.

• Korean Journal of Environmental Biology
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• v.17 no.2
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• pp.199-204
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• 1999

The effects of temperature stress and paraquat on the superoxide dismutase (SOD) activity and the photochemical efficiency of photosystem II were studied in the leaves of Araliaceae plants. The SOD activity of Acanthopanax koreanum leaf discs increased at 4$^{\circ}C$ and 28$^{\circ}C$, and increased significantly at 4$^{\circ}C$ ,28$^{\circ}C$ and 35$^{\circ}C$ in the presence of paraquat. However, the SOD activity of Dendropanax morbifera leaf discs decreased at 4$^{\circ}C$, 28$^{\circ}C$ and 35$^{\circ}C$ regardless of paraquat treatment. The photochemical efficiency of photosystem II, Fv/Fm, of leaf discs of A. koreanum and D. morbifera fell remarkably at 35$^{\circ}C$. In the presence of paraquat, the Ev/Fm values fell slightly at 4$^{\circ}C$ in A. koreanum leaf discs and at 35$^{\circ}C$, in D. morbifera leaf discs. These results indicate that A. koreanum plants are more resistant to temperature stress or oxidative stress than D. morbifera plants although their photochemical efficiency falls slightly at 4$^{\circ}C$ in the presence of paraquat.

• Plant Resources
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• v.4 no.1
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• pp.36-40
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• 2001

Transgenic Petunia hybrida cv. Rosanpion was produced by Agrobactepium tumefaciens LBA4404 harboring a binary vector pBI 121 containing $\beta$-glucuronidase (gus) and neomycin phosphotransferase (nptII). For genetic transformation, leaf discs were precultured on MS medium supplemented with 0.5 mg/L NAA and 1.0 mg/L BA (MNB) for 2 days and cocultured for 15 mins with A. tumefaciens. For selection of transformant, leaf discs were transferred to fresh MNB containing 50 mg/L kanamycin and 500 mg/L cefotaxime. Eighteen plants were regenerated and four were confirmed by PCR for detection of gus and nptII gene integrated into the nuclear genome of petunia ‘Rosanpion’. Using this transformation system, we expect that transgenic petunia ‘Rosanpion’ incorporating a useful gene can be produced.