title: Stress tolerance in transgenic tobacco seedlings that overexpress glutathione S-transferase/glutathione peroxidase.
abstract: Overexpression of a tobacco glutathione S-transferase with glutathione peroxidase activity (GST/GPX) in transgenic tobacco (Nicotiana tabacum L.) enhanced seedling growth under a variety of stressful conditions. In addition to increased GST and GPX activity, transgenic GST/GPX-expressing (GST+) seedlings had elevated levels of monodehydroascorbate reductase activity. GST+ seedlings also contained higher levels of glutathione and ascorbate than wild-type seedlings and the glutathione pools were more oxidized. Thermal or salt-stress treatments that inhibited the growth of wild-type seedlings also caused increased levels of lipid peroxidation. These treatments had less effect on the growth of GST+ seedling growth and did not lead to increased lipid peroxidation. Stress-induced damage resulted in reduced metabolic activity in wild-type seedlings while GST+ seedlings maintained metabolic activity levels comparable to seedlings grown under control conditions. These results indicate that overexpression of GST/GPX in transgenic tobacco seedlings provides increased glutathione-dependent peroxide scavenging and alterations in glutathione and ascorbate metabolism that lead to reduced oxidative damage. We conclude that this protective effect is primarily responsible for the ability of GST+ seedlings to maintain growth under stressful conditions.
authors.affiliation: Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA.
authors.forename: V P
authors.initials: VP
authors.lastname: Roxas
authors.forename: S A
authors.initials: SA
authors.lastname: Lodhi
authors.forename: D K
authors.initials: DK
authors.lastname: Garrett
authors.forename: J R
authors.initials: JR
authors.lastname: Mahan
authors.forename: R D
authors.initials: RD
authors.lastname: Allen
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics; D001205:Ascorbic Acid / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D005838:Genotype; D005978:Glutathione / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000235:genetics / Q000378:metabolism*; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism*; D015227:Lipid Peroxidation; D010084:Oxidation-Reduction; D063245:Plant Development; D010944:Plants / Q000235:genetics*; D030821:Plants, Genetically Modified; D010947:Plants, Toxic; D013696:Temperature; D014026:Nicotiana / Q000235:genetics* / Q000254:growth & development
chemical_list: D005979:Glutathione Peroxidase; D005982:Glutathione Transferase; D005978:Glutathione; D001205:Ascorbic Acid