Enhanced tolerance of transgenic sweetpotato plants that express both CuZnSOD and APX in chloroplasts to methyl viologen-mediated oxidative stress and chilling |
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Authors: | Soon Lim Yun-Hee Kim Sun-Hyung Kim Suk-Yoon Kwon Haeng-Soon Lee Jin-Seog Kim Kwang-Yun Cho Kee-Yoeup Paek Sang-Soo Kwak |
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Institution: | (1) Environmental Biotechnology Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Oun-dong 52, Yuseong-gu, Daejeon, 305-806, Korea;(2) Biofunction Research Team, Bioorganic Science Division, Korea Research Institute of Chemical Technology (KRICT), P.O. Box 107, Yuseong-gu, Daejeon, 305-600, Korea;(3) Department of Horticulture, Chungbuk National University, Cheongju, 361-763, Korea |
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Abstract: | Oxidative stress is one of the major factors causing injury to plants exposed to environmental stress. Transgenic sweetpotato
Ipomoea batatas (L.) Lam. cv. Yulmi] plants with an enhanced tolerance to multiple environmental stresses were developed by expressing the
genes of both CuZn superoxide dismutase (CuZnSOD) and ascorbate peroxidase (APX) under the control of an oxidative stress-inducible
SWPA2 promoter in the chloroplasts of sweetpotato plants (referred to as SSA plants). SSA plants were successfully generated by
the particle bombardment method and confirmed by PCR analysis. When leaf discs of SSA plants were subjected to 5 μM methyl viologen (MV), they showed approximately 45% less damage than non-transformed (NT) plants. When 200 μM MV was sprayed onto the whole plants, SSA plants showed a significant reduction in visible damage compared to leaves of NT
plants, which were almost destroyed. The expression of the introduced CuZnSOD and APX genes in leaves of SSA plants following
MV treatment was significantly induced, thereby reflecting increased levels of SOD and APX in the chloroplasts. APX activity
in chloroplast fractions isolated from SSA plants was approximately 15-fold higher than that in their counterparts from NT
plants. SSA plants treated with a chilling stress consisting of 4°C for 24 h exhibited an attenuated decrease in photosynthetic
activity (Fv/Fm) relative to NT plants; furthermore, after 12 h of recovery following chilling, the Fv/Fm of SSA plants almost
fully recovered to the initial levels, whereas NT plants remained at a lower level of Fv/Fm activity. These results suggest
that SSA plants would be a useful plant crop for commercial cultivation under unfavorable growth conditions. In addition,
the manipulation of the antioxidative mechanism in chloroplasts can be applied to the development of various other transgenic
crops with an increased tolerance to multiple environmental stresses. |
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Keywords: | Ascorbate peroxidase Chilling stress Chloroplast Oxidative stress Superoxide dismutase Sweetpotato |
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