Stress tolerance in transgenic tobacco seedlings that overexpress glutathione S-transferase/glutathione peroxidase

• Published in: Plant and cell physiology 2000-11, Vol.41 (11), p.1229-1234
• Main Authors: Roxas, V.P. (Texas Tech Univ., Lubbock (USA)), Lodhi, S.A, Garrett, D.K, Mahan, J.R, Allen, R.D
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological - genetics; APX; ASA; ascorbate peroxidase; ascorbic acid; Ascorbic Acid - metabolism; days post-imbibition; dehydroascorbate; dehydroascorbate reductase; DHA; DHAR; DPI; ENZYMIC ACTIVITY; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Genotype; GLUTATHIONE; Glutathione - metabolism; GLUTATHIONE PEROXIDASE; Glutathione Peroxidase - genetics; Glutathione Peroxidase - metabolism; glutathione reductase; glutathione S-transferase; Glutathione Transferase - genetics; Glutathione Transferase - metabolism; GPX glutathione peroxidase; GROWTH; GSH; GSSG; GST; Key words: Glutathione peroxidase — Glutathione S-transferase — Seedling growth — Stress tolerance — Transgenic tobacco; Lipid Peroxidation; malondialdehyde; MDA; MDHA; MDHAR; monodehydroascorbate; monodehydroascorbate reductase; Nicotiana - genetics; Nicotiana - growth & development; NICOTIANA TABACUM; Oxidation-Reduction; oxidized glutathione; Plant Development; Plants - genetics; Plants, Genetically Modified; Plants, Toxic; reduced glutathione; RESISTANCE TO INJURIOUS FACTORS; SEEDLINGS; Temperature; TRANSFERASES; TRANSGENIC PLANTS
• ISSN: 0032-0781; 1471-9053
• DOI: 10.1093/pcp/pcd051

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.