• Journal of Plant Biotechnology
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• 제41권2호
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• pp.73-80
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• 2014

산화질소(nitric oxide: NO) 공여체인 $100{\mu}M$ sodium nitroprusside (SNP)를 배추 잎에 전처리한 후 이어서 $2{\mu}M$ paraquat (PQ)처리 시, PQ에 의해 유도된 산화적 손상에 대한 잎의 내성이 효과적으로 증진되었다. 24 시간 광 배양기간 동안 PQ 단독 처리구 잎에서는 생체량, 엽록소 및 단백질 함량이 현저하게 감소하였으나 PQ 노출 전에 3시간 SNP 전처리로 이들 잎 손상이 의미 있게 완화되었다. 게다가 PQ 처리에 기인된 malondialdehyde (MDA)와 $H_2O_2$ 함량 증가도 SNP 전처리에 의해 유의하게 억제되었다. 잎에서 이들 PQ 독성에 대한 SNP의 방어효과와 관련하여 ascorbate-glutathione 회로 구성 효소의 활성도 변화를 조사하였다. PQ 단독 처리구에서 APX, DHAR 및 GR 효소 활성도는 배양 6시간후에 급격히 감소되어 대조구 잎과 비교 시 각각 대조구의 19%, 50%, 39% 수준의 활성도 값을 보였다. 그러나, 이들 효소 활성도 값 감소는 SNP 전처리에 의해 현저하게 억제되어 6시간 배양 후에 PQ 단독처리구 보다 각각 5배, 2배, 1.5배 높은 값을 나타내었다. 또한, 그 이후 24시간 배양 때까지 PQ 단독 처리구보다 계속 높은 활성도를 보이면서 점차로 감소하였다. 이들 결과로부터, PQ에 노출된 배추 잎에서 SNP 전처리에 의한 ascorbate-glutathione 회로의 활성화가 $H_2O_2$의 축적을 억제하며 그로인해 PQ에 의해 유도된 산화스트레스로부터 잎을 방어하는 것으로 생각되었다. 동시에 이 들 결과는 산화질소가 배추 잎에서 PQ 스트레스에 대한 항산화 방어자로서의 역할을 하는 것을 의미한다.

• Journal of Ginseng Research
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• 제41권3호
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• pp.307-315
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• 2017

Background: Red-skin root disease has seriously decreased the quality and production of Panax ginseng (ginseng). Methods: To explore the disease's origin, comparative analysis was performed in different parts of the plant, particularly the epidermis, cortex, and/or fibrous roots of 5-yr-old healthy and diseased red-skin ginseng. The inorganic element composition, phenolic compound concentration, reactive oxidation system, antioxidant concentrations such as ascorbate and glutathione, activities of enzymes related to phenolic metabolism and oxidation, and antioxidative system particularly the ascorbate-glutathione cycle were examined using conventional methods. Results: Aluminum (Al), iron (Fe), magnesium, and phosphorus were increased, whereas manganese was unchanged and calcium was decreased in the epidermis and fibrous root of red-skin ginseng, which also contained higher levels of phenolic compounds, higher activities of the phenolic compound-synthesizing enzyme phenylalanine ammonia-lyase and the phenolic compound oxidation-related enzymes guaiacol peroxidase and polyphenoloxidase. As the substrate of guaiacol peroxidase, higher levels of $H_2O_2$ and correspondingly higher activities of superoxide dismutase and catalase were found in red-skin ginseng. Increased levels of ascorbate and glutathione; increased activities of $\text\tiny L$-galactose 1-dehydrogenase, ascorbate peroxidase, ascorbic acid oxidase, and glutathione reductase; and lower activities of dehydroascorbate reductase, monodehydroascorbate reductase, and glutathione peroxidase were found in red-skin ginseng. Glutathione-S-transferase activity remained constant. Conclusion: Hence, higher element accumulation, particularly Al and Fe, activated multiple enzymes related to accumulation of phenolic compounds and their oxidation. This might contribute to red-skin symptoms in ginseng. It is proposed that antioxidant and antioxidative enzymes, especially those involved in ascorbate-glutathione cycles, are activated to protect against phenolic compound oxidation.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2010년도 정기총회 및 추계학술발표회
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• pp.14-14
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• 2010

Vitamin C (ascorbic acid) is an essential component for collagen biosynthesis and also for the proper functioning of the cardiovascular system in humans. Unlike most of the animals, humans lack the ability to synthesize ascorbic acid on their own due to a mutation in the gene encoding the last enzyme of ascorbate biosynthesis. As a result, vitamin C must be obtained from dietary sources like plants. In this study, we have developed two different kinds of transgenic potato plants (Solanumtuberosum L. cv. Taedong Valley) overexpressing strawberry GalUR and mouse GLoase gene under the control of CaMV 35S promoter with increased ascorbic acid levels. Integration of the these genes in the plant genome was confirmed by PCR and Southern blotting. Ascorbic acid(AsA) levels in transgenic tubers were determined by high-performance liquid chromatography(HPLC). The over-expression of these genes resulted in 2-4 folds increase in AsA intransgenic potato and the levels of AsA were positively correlated with increased geneactivity. The transgenic lines with enhanced vitamin C content showed enhanced tolerance to abiotic stresses induced by methyl viologen(MV), NaCl or mannitol as compared to untransformed control plants. The leaf disc senescence assay showed better tolerance in transgenic lines by retaining higher chlorophyll as compared to the untransformed control plants. Present study demonstrated that the over-expression of these gene enhanced the level of AsA in potato tubers and these transgenics performed better under different abiotic stresses as compared to untransformed control. We have also investigated the mechanism of the abiotic stress tolerance upon enhancing the level of the ascorbate in transgenic potato. The transgenic potato plants overexpressing GalUR gene with enhanced accumulation of ascorbate were investigated to analyze the antioxidants activity of enzymes involved in the ascorbate-glutathione cycle and their tolerance mechanism against different abiotic stresses under invitro conditions. Transformed potato tubers subjected to various abiotic stresses induced by methyl viologen, sodium chloride and zinc chloride showed significant increase in the activities of superoxide dismutase(SOD, EC 1.15.1.1), catalase, enzymes of ascorbate-glutathione cycle enzymes such as ascorbate peroxidase(APX, EC 1.11.1.11), dehydroascorbate reductase(DHAR, EC 1.8.5.1), and glutathione reductase(GR, EC 1.8.1.7) as well as the levels of ascorbate, GSH and proline when compared to the untransformed tubers. The increased enzyme activities correlated with their mRNA transcript accumulation in the stressed transgenic tubers. Pronounced differences in redox status were also observed in stressed transgenic potato tubers that showed more tolerance to abiotic stresses when compared to untransformed tubers. From the present study, it is evident that improved to lerance against abiotic stresses in transgenic tubers is due to the increased activity of enzymes involved in the antioxidant system together with enhanced ascorbate accumulated in transformed tubers when compared to untransformed tubers. At moment we also investigating the role of enhanced reduced glutathione level for the maintenance of the methylglyoxal level as it is evident that methylglyoxal is a potent cytotoxic compound produced under the abiotic stress and the maintenance of the methylglyoxal level is important to survive the plant under stress conditions.

• The Korean Journal of Ecology
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• 제26권5호
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• pp.273-280
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• 2003

해안에 주로 분포하는 Atriplex gmelini(가는갯능쟁이)의 염 내성이 항산화 효소의 활성증가에 의한 것인가를 조사하기 위해 다양한 농도의 염 처리에 의한 광계 Ⅱ 양자효율 및 항산화 효소의 활성 변화를 조사하였다. A. gmelini는 100 mM NaCl처리구에서 가장 높은 지상부 건물함량(대조구의 116%) 및 최적의 생장을 보였으며, 300 mM NaCl처리에 의해서도 체내 수분함량과 건물량의 감소를 보이지 않아 염에 대한 높은 내성을 보였다. 단기간(2, 4일)의 염 처리시 외부 염 농도 구배에 따른 Fv/Fm값(양자효율)의 증가, Fo/Fm값(스트레스지표)의 감소 및 SOD, APX, GR과 같은 항산화 효소의 활성 증가를 나타내어 광화학적 스트레스 혹은 항산화 방어시스템의 손상을 보이지 않았다. 그러나 400 mM NaCl을 처리한 식물의 경우, 비록 대조구(0 mM NaCl)에 비해 높은 항산화 효소 활성값(SOD 171%, APX 114%, GR 134%)을 보였지만 생장감소(잎, 줄기 각각 30%, 16%) 및 고농도 염에 의한 활성의 감소양상을 나타내었다. 흥미롭게도, H₂O₂제거에 중요한 역할을 하는 또 다른 효소인 CAT의 활성이 염에 의한 빠른 감소(200, 300, 400 mM NaCl 처리구의 경우 각각 대조구의 38%, 22%, 15%)를 보여, A. gmelini는 염에 의해 생성된 활성산소 제거와 염분 내성에 ascorbate-glutathione cycle의 APX, GR이 중요한 역할을 수행하는 것으로 생각된다. 그러나, 염 처리 6일 후, Fv/Fm값의 감소, Fo/Fm값의 증가 및 항산화 효소의 활성감소를 보여 광화학적 저해 및 항산화 방어시스템의 손상을 나타내었다. A. gmelini는 단기간의 염 처리(염 처리 2, 4일)시, 염에 의해 유도된 ROS증가에 대해 항산화 시스템의 활성 강화를 통해 균형을 이루지만, 6일 이상의 지속적인 염에 의해서는 항산화 효소의 활성감소와 광화학적 손상으로 인한 ROS증가로 산화적 스트레스가 유발되는 것으로 여겨진다.