Enhanced stress-tolerance of transgenic tobacco plants expressing a human dehydroascorbate reductase gene.
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.
Kwon
Suk-Yoon
SY
Laboratory of Environmental Biotechnology, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Oun-dong 52, Yusong-gu, Daejeon 305-806, Korea.
Choi
Sun-Mee
SM
Ahn
Young-Ock
YO
Lee
Haeng-Soon
HS
Lee
Hae-Bok
HB
Park
Yong-Mok
YM
Kwak
Sang-Soo
SS
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
D012965:Sodium Chloride; D006861:Hydrogen Peroxide; D010088:Oxidoreductases; C020666:glutathione dehydrogenase (ascorbate); D010269:Paraquat