Simultaneous overexpression of both CuZn superoxide dismutase and ascorbate peroxidase in transgenic tall fescue plants confers increased tolerance to a wide range of abiotic stresses.
To mitigate the oxidative damage inflicted by biotic or abiotic stresses, plants have evolved complex anti-oxidative defense mechanisms that involve induction of antioxidant and anti-oxidative enzymes, such as superoxide dismutase (SOD) and ascorbate peroxidase (APX). To determine whether overexpression of the genes encoding copper-zinc SOD (CuZnSOD) and APX in plants is capable of decreasing reactive oxygen species (ROS) produced in response to abiotic stresses, we generated transgenic tall fescue plants expressing the CuZnSOD and APX genes in chloroplasts under the control of the oxidative stress-inducible promoter, sweet potato peroxidase anionic 2 (SWPA2). Transgenic plants were generated by Agrobacterium-mediated genetic transformation, and genotypes were confirmed by DNA blot analysis. Transgenic plants were exposed to several ROS-generating abiotic stresses, such as methyl viologen (MV), H(2)O(2), and the heavy metals copper, cadmium, and arsenic, and their tolerance was evaluated. High levels of CuZnSOD and APX gene transcripts in the transgenic plants under these treatments suggested that the transgenes were functionally expressed. Compared to transgenic plants, higher amounts of ROS were generated in the leaves of control plants exposed to abiotic stresses, resulting in increased thiobarbituric acid reactive substances (TBARS), ion leakage, and chlorophyll degradation. These parameters were significantly lower in transgenic plants. Enzyme activity assays and native polyacrylamide gel electrophoresis (PAGE) showed that total SOD and APX were highly active in transgenic plants under the abiotic stresses examined. We conclude that one of the mechanisms of increased anti-oxidative defense in transgenic tall fescue plants is overexpression of the CuZnSOD and APX genes, which are utilized in scavenging ROS and thus provide improved tolerance to abiotic stresses.
Lee
Sang-Hoon
SH
Major of Dairy Science, Division of Applied Life Science (BK21), PMBBRC, College of Agriculture and Life Sciences, Gyeongsang National University, Jinju 660-701, Korea.
Ahsan
Nagib
N
Lee
Ki-Won
KW
Kim
Do-Hyun
DH
Lee
Dong-Gi
DG
Kwak
Sang-Soo
SS
Kwon
Suk-Yoon
SY
Kim
Tae-Hwan
TH
Lee
Byung-Hyun
BH
D000222:Adaptation, Physiological / Q000187:drug effects; D000975:Antioxidants / Q000378:metabolism; D060387:Ascorbate Peroxidases; D016923:Cell Death / Q000187:drug effects; D002734:Chlorophyll / Q000378:metabolism; D004269:DNA, Bacterial; D018744:DNA, Plant / Q000378:metabolism; D031751:Festuca / Q000166:cytology / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics*; D015870:Gene Expression / Q000187:drug effects; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D019216:Metals, Heavy / Q000494:pharmacology; D010269:Paraquat / Q000494:pharmacology; D010544:Peroxidases / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism*; D014170:Transformation, Genetic / Q000187:drug effects; D019076:Transgenes
D000975:Antioxidants; D004269:DNA, Bacterial; D018744:DNA, Plant; D007527:Isoenzymes; D019216:Metals, Heavy; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; C036483:T-DNA; D002734:Chlorophyll; D006861:Hydrogen Peroxide; D010544:Peroxidases; D060387:Ascorbate Peroxidases; D013482:Superoxide Dismutase; D010269:Paraquat