title: Overexpression of the glutamine synthetase gene modulates oxidative stress response in rice after exposure to cadmium stress.
abstract: Overexpression of OsGS gene modulates oxidative stress response in rice after exposure to cadmium stress. Our results describe the features of transformants with enhanced tolerance to Cd and abiotic stresses. Glutamine synthetase (GS) (EC 6.3.1.2) is an enzyme that plays an essential role in the metabolism of nitrogen by catalyzing the condensation of glutamate and ammonia to form glutamine. Exposure of plants to cadmium (Cd) has been reported to decrease GS activity in maize, pea, bean, and rice. To better understand the function of the GS gene under Cd stress in rice, we constructed a recombinant pART vector carrying the GS gene under the control of the CaMV 35S promoter and OCS terminator and transformed using Agrobacterium tumefaciens. We then investigated GS overexpressing rice lines at the physiological and molecular levels under Cd toxicity and abiotic stress conditions. We observed a decrease in GS enzyme activity and mRNA expression among transgenic and wild-type plants subjected to Cd stress. The decrease, however, was significantly lower in the wild type than in the transgenic plants. This was further validated by the high GS mRNA expression and enzyme activity in most of the transgenic lines. Moreover, after 10 days of exposure to Cd stress, increase in the glutamine reductase activity and low or no malondialdehyde contents were observed. These results showed that overexpression of the GS gene in rice modulated the expression of enzymes responsible for membrane peroxidation that may result in plant death.
authors.affiliation: Department of Crop Science, Chungbuk National University, Cheongju, 361-763, Korea.
authors.forename: Hye Jung
authors.initials: HJ
authors.lastname: Lee
authors.forename: Sailila E
authors.initials: SE
authors.lastname: Abdula
authors.forename: Dae Won
authors.initials: DW
authors.lastname: Jang
authors.forename: Sung-Han
authors.initials: SH
authors.lastname: Park
authors.forename: Ung-Han
authors.initials: UH
authors.lastname: Yoon
authors.forename: Yu Jin
authors.initials: YJ
authors.lastname: Jung
authors.forename: Kwon Kyoo
authors.initials: KK
authors.lastname: Kang
authors.forename: Ill Sup
authors.initials: IS
authors.lastname: Nou
authors.forename: Yong-Gu
authors.initials: YG
authors.lastname: Cho
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002104:Cadmium / Q000494:pharmacology*; D018506:Gene Expression Regulation, Plant; D005974:Glutamate-Ammonia Ligase / Q000235:genetics / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism; D015227:Lipid Peroxidation; D008315:Malondialdehyde / Q000378:metabolism; D008969:Molecular Sequence Data; D012275:Oryza / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D018384:Oxidative Stress; D018515:Plant Leaves / Q000201:enzymology; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics / Q000502:physiology; D011401:Promoter Regions, Genetic
chemical_list: D002104:Cadmium; D008315:Malondialdehyde; D006861:Hydrogen Peroxide; D005974:Glutamate-Ammonia Ligase