Enhanced tolerance to oxidative stress in transgenic tobacco plants expressing three antioxidant enzymes in chloroplasts.
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.
Lee
Young-Pyo
YP
Environmental Biotechnology Research Center, KRIBB, Eoeun-dong 52, Yuseong-gu, Daejeon, 305-806 Korea.
Kim
Sun-Hyung
SH
Bang
Jae-Wook
JW
Lee
Haeng-Soon
HS
Kwak
Sang-Soo
SS
Kwon
Suk-Yoon
SY
D000222:Adaptation, Physiological / Q000187:drug effects; D000975:Antioxidants / Q000378:metabolism*; D060387:Ascorbate Peroxidases; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002736:Chloroplasts / Q000187:drug effects / Q000201:enzymology*; D004798:Enzymes / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D010544:Peroxidases / Q000378:metabolism; D018515:Plant Leaves / Q000166:cytology / Q000187:drug effects; D030821:Plants, Genetically Modified; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development; D012965:Sodium Chloride / Q000494:pharmacology; D013482:Superoxide Dismutase / Q000378:metabolism; D014026:Nicotiana / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics*
D000975:Antioxidants; D004798:Enzymes; D012965:Sodium Chloride; D010088:Oxidoreductases; D010544:Peroxidases; D060387:Ascorbate Peroxidases; D013482:Superoxide Dismutase; C020666:glutathione dehydrogenase (ascorbate)