1999
DOI: 10.1105/tpc.11.7.1277
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Elevated Glutathione Biosynthetic Capacity in the Chloroplasts of Transgenic Tobacco Plants Paradoxically Causes Increased Oxidative Stress

Abstract: Glutathione (GSH), a major antioxidant in most aerobic organisms, is perceived to be particularly important in plant chloroplasts because it helps to protect the photosynthetic apparatus from oxidative damage. In transgenic tobacco plants overexpressing a chloroplast-targeted ␥ -glutamylcysteine synthetase ( ␥ -ECS), foliar levels of GSH were raised threefold. Paradoxically, increased GSH biosynthetic capacity in the chloroplast resulted in greatly enhanced oxidative stress, which was manifested as light inten… Show more

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Cited by 318 publications
(198 citation statements)
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“…Elevated GR activity should lead to more reduced glutathione which would generally be regarded as beneficial for redox homeostasis in chloroplasts (Mittler 2002). However, our finding matches that of Creissen et al (1999) who increased GSH levels by transformation with a gene for a chloroplast-targeted c-glutamylcysteine synthetase (c-ECS) and found increased oxidative stress, which they explained on the basis of impaired redox sensing in the chloroplast. We contend that the increased MV sensitivity of the transplastomic lines over-expressing GR has a similar basis, although it is not reflected in a study in poplar (Foyer et al 1995) in which chloroplast targeted GR did result in improved oxidative stress tolerance.…”
Section: Discussionsupporting
confidence: 64%
“…Elevated GR activity should lead to more reduced glutathione which would generally be regarded as beneficial for redox homeostasis in chloroplasts (Mittler 2002). However, our finding matches that of Creissen et al (1999) who increased GSH levels by transformation with a gene for a chloroplast-targeted c-glutamylcysteine synthetase (c-ECS) and found increased oxidative stress, which they explained on the basis of impaired redox sensing in the chloroplast. We contend that the increased MV sensitivity of the transplastomic lines over-expressing GR has a similar basis, although it is not reflected in a study in poplar (Foyer et al 1995) in which chloroplast targeted GR did result in improved oxidative stress tolerance.…”
Section: Discussionsupporting
confidence: 64%
“…Hydrochloric acid (0.1 M) extracts from 100 mg of fresh Arabidopsis tissue ground in liquid nitrogen were prepared and purified over activated charcoal as described by Creissen et al (1999). H 2 O 2 concentrations in purified extracts were determined using an Amplex Red assay kit (Invitrogen) according to the manufacturer's instructions.…”
Section: Total Foliar H 2 O 2 Measurementsmentioning
confidence: 99%
“…have extensively reviewed several studies showing the importance of GR in the defense against oxidative stress. In contrast, an increased sensitivity to oxidative stress in transgenic plants with elevated GSH levels by either overexpression of γ-glutamylecysteine synthetase (γ-ECS), glutathione synthetase (GS) or GR has been also reported (Creissen et al 1999, Logan et al 2003.…”
Section: Introductionmentioning
confidence: 98%