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.

Proline and Glycinebetaine Ameliorated NaCl Stress via Scavenging of Hydrogen Peroxide and Methylglyoxal but Not Superoxide or Nitric Oxide in Tobacco Cultured Cells

“…5), although both increased activity of glyoxalase I under such stress, 8) which can contribute to the detoxification of MG. Overexpression or higher activity of GPX in plants increases antioxidant activity and improves tolerance of oxidative stress. 39,40) Taken together, the increased activity and/or expression of H 2 O 2 -and MG-scavenging enzymes and/or genes in tobacco BY-2 cells grown with exogenous proline or betaine under NaCl stress suggests greater protection against the damaging effects of H 2 O 2 and MG. 8,12,28,29) In conclusion, proline and betaine do not modulate the early response to salt stress and production of O 2 À and NO, but do mitigate late response to salt stress and the production of H 2 O 2 and MG. Proline and betaine can alleviate a variety of environmental stresses, since the late response to salt stress appears to be similar to the response elicited by various environmental stresses, but the reduction of accumulation of H 2 O 2 and MG due to proline and betaine might be imperative in avoiding cellular damage and increasing salt tolerance.…”

Identifying Differentially Expressed Genes Associated with Tolerance against Low Temperature Stress in Brassica napus through Transcriptome Analysis

“…Overexpression of GST can stimulate seedling growth under chilling and salt stress, and this effect could be caused by oxidation of the glutathione pool (Roxas et al, 1997). 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 (Roxas et al, 2000). Secondary metabolism and its products also play an important role in rapeseed response to low temperature stress response.…”

Relationships among lipid peroxidation, SOD enzyme activity, and SOD gene expression profile in Lycopersicum esculentum L. exposed to cold stress

“…Overexpression of antioxidant genes, such as GR, APX, SOD, etc., have been demonstrated to provide enhanced tolerance to ROS-induced stress in several crop species (Roxas et al, 2000;Shinozaki and Yamaguchi-Shinozaki, 2000;Payton et al, 2001;Dai et al, 2009;Goupil et al, 2009;Fortunato et al, 2010). Different gene encoding factors involved in signal transduction cascades, such as transcription factors, are induced by stress treatments, which in turn might affect expression patterns of antioxidant genes (Shinozaki and Yamaguchi-Shinozaki, 1996).…”