Enhanced tolerance to oxidative stress in transgenic tobacco plants expressing three antioxidant enzymes in chloroplasts |
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Authors: | Young-Pyo Lee Sun-Hyung Kim Jae-Wook Bang Haeng-Soon Lee Sang-Soo Kwak Suk-Yoon Kwon |
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Institution: | (1) Environmental Biotechnology Research Center, KRIBB, Eoeun-dong 52, Yuseong-gu, Daejeon, 305-806, Korea;(2) Department of Biology, Chungnam National University, Daejeon, 305-764, Korea;(3) Department of Environmental Horticulture, University of Seoul, Seoul, 130-743, Korea |
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Abstract: | The effect of simultaneous expression of genes encoding three antioxidant enzymes, copper zinc superoxide dismutase (CuZnSOD,
EC 1.15.1.1), ascorbate peroxidase (APX, EC 1.11.1.11), and dehydroascorbate (DHA) reductase (DHAR, EC 1.8.5.1), in the chloroplasts
of tobacco plants was investigated under oxidative stress conditions. In previous studies, transgenic tobacco plants expressing
both CuZnSOD and APX in chloroplast (CA plants), or DHAR in chloroplast showed enhanced tolerance to oxidative stresses, such
as paraquat and salt. In this study, in order to develop transgenic plants that were more resistant to oxidative stress, we
introduced the gene encoding DHAR into CA transgenic plants. Mature leaves of transgenic plants expressing all three antioxidant
genes (CAD plants) had approximately 1.6–2.1 times higher DHAR activity, and higher ratios of reduced ascorbate (AsA) to DHA,
and oxidized glutathione (GSSG) to reduced glutathione (GSH) compared to CA plants. CAD plants were more resistant to paraquat-induced
stress, exhibiting only 18.1% reduction in membrane damage relative to CA plants. In addition, seedlings of CAD plants had
enhanced tolerance to NaCI (100 mM) compared to CA plants. These results indicate that the simultaneous expression of multiple
antioxidant enzymes, such as CuZnSOD, APX, and DHAR, in chloroplasts is more effective than single or double expression for
developing transgenic plants with enhanced tolerance to multiple environmental stresses. |
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Keywords: | Ascorbate Ascorbate peroxidase Chloroplast Dehydroascorbate reductase Glutathione Methyl viologen Oxidative stress Superoxide dismutase |
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