title: Enhanced stress-tolerance of transgenic tobacco plants expressing a human dehydroascorbate reductase gene.
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.
authors.affiliation: Laboratory of Environmental Biotechnology, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Oun-dong 52, Yusong-gu, Daejeon 305-806, Korea.
authors.forename: Suk-Yoon
authors.initials: SY
authors.lastname: Kwon
authors.forename: Sun-Mee
authors.initials: SM
authors.lastname: Choi
authors.forename: Young-Ock
authors.initials: YO
authors.lastname: Ahn
authors.forename: Haeng-Soon
authors.initials: HS
authors.lastname: Lee
authors.forename: Hae-Bok
authors.initials: HB
authors.lastname: Lee
authors.forename: Yong-Mok
authors.initials: YM
authors.lastname: Park
authors.forename: Sang-Soo
authors.initials: SS
authors.lastname: Kwak
mesh_terms: D000222:Adaptation, Physiological; D003080:Cold Temperature; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D010088:Oxidoreductases / Q000235:genetics*; D010269:Paraquat / Q000494:pharmacology; D018515:Plant Leaves / Q000187:drug effects; D030821:Plants, Genetically Modified / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D012965:Sodium Chloride / Q000008:administration & dosage; D014026:Nicotiana / Q000235:genetics* / Q000378:metabolism / Q000502:physiology
chemical_list: D012965:Sodium Chloride; D006861:Hydrogen Peroxide; D010088:Oxidoreductases; C020666:glutathione dehydrogenase (ascorbate); D010269:Paraquat