Enhanced stress-tolerance of transgenic tobacco plants expressing a human dehydroascorbate reductase gene |
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Authors: | Kwon Suk-Yoon Choi Sun-Mee Ahn Young-Ock Lee Haeng-Soon Lee Hae-Bok Park Yong-Mok Kwak Sang-Soo |
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Institution: | Laboratory of Environmental Biotechnology, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Oun-dong 52, Yusong-gu, Daejeon 305-806, Korea. |
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Abstract: | To analyze the physiological role of dehydroascorbate reductase (DHAR, EC 1.8.5.1) catalyzing the reduction of DHA to ascorbate in environmental stress adaptation, T1 transgenic tobacco (Nicotiana tabacum cv. Xanthi) plants expressing a human DHAR gene in chloroplasts were biochemically characterized and tested for responses to various stresses. Fully expanded leaves of transgenic plants had about 2.29 times higher DHAR activity (units/g fresh wt) than non-transgenic (NT) plants. Interestingly, transgenic plants also showed a 1.43 times higher glutathione reductase activity than NT plants. As a result, the ratio of AsA/DHA was changed from 0.21 to 0.48, even though total ascorbate content was not significantly changed. When tobacco leaf discs were subjected to methyl viologen (MV) at 5 mumol/L and hydrogen peroxide (H2O2) at 200 mmol/L, transgenic plants showed about a 40% and 25% reduction in membrane damage relative to NT plants, respectively. Furthermore, transgenic seedlings showed enhanced tolerance to low temperature (15 degrees C) and NaCl (100 mmol/L) compared to NT plants. These results suggest that a human derived DHAR properly works for the protection against oxidative stress in plants. |
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Keywords: | ascorbic acid dehydroascorbate reductase glutathione methyl viologen oxidative stress transgenic tobacco plant |
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