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      Dynamic compartment specific changes in glutathione and ascorbate levels in Arabidopsis plants exposed to different light intensities

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          Abstract

          Background

          Excess light conditions induce the generation of reactive oxygen species (ROS) directly in the chloroplasts but also cause an accumulation and production of ROS in peroxisomes, cytosol and vacuoles. Antioxidants such as ascorbate and glutathione occur in all cell compartments where they detoxify ROS. In this study compartment specific changes in antioxidant levels and related enzymes were monitored among Arabidopsis wildtype plants and ascorbate and glutathione deficient mutants ( vtc2-1 and pad2-1, respectively) exposed to different light intensities (50, 150 which was considered as control condition, 300, 700 and 1,500 μmol m -2 s -1) for 4 h and 14 d.

          Results

          The results revealed that wildtype plants reacted to short term exposure to excess light conditions with the accumulation of ascorbate and glutathione in chloroplasts, peroxisomes and the cytosol and an increased activity of catalase in the leaves. Long term exposure led to an accumulation of ascorbate and glutathione mainly in chloroplasts. In wildtype plants an accumulation of ascorbate and hydrogen peroxide (H 2O 2) could be observed in vacuoles when exposed to high light conditions. The pad2-1 mutant reacted to long term excess light exposure with an accumulation of ascorbate in peroxisomes whereas the vtc2-1 mutant reacted with an accumulation of glutathione in the chloroplasts (relative to the wildtype) and nuclei during long term high light conditions indicating an important role of these antioxidants in these cell compartments for the protection of the mutants against high light stress.

          Conclusion

          The results obtained in this study demonstrate that the accumulation of ascorbate and glutathione in chloroplasts, peroxisomes and the cytosol is an important reaction of plants to short term high light stress. The accumulation of ascorbate and H 2O 2 along the tonoplast and in vacuoles during these conditions indicates an important route for H 2O 2 detoxification under these conditions.

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          Most cited references61

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          Glutathione in plants: an integrated overview.

          Plants cannot survive without glutathione (γ-glutamylcysteinylglycine) or γ-glutamylcysteine-containing homologues. The reasons why this small molecule is indispensable are not fully understood, but it can be inferred that glutathione has functions in plant development that cannot be performed by other thiols or antioxidants. The known functions of glutathione include roles in biosynthetic pathways, detoxification, antioxidant biochemistry and redox homeostasis. Glutathione can interact in multiple ways with proteins through thiol-disulphide exchange and related processes. Its strategic position between oxidants such as reactive oxygen species and cellular reductants makes the glutathione system perfectly configured for signalling functions. Recent years have witnessed considerable progress in understanding glutathione synthesis, degradation and transport, particularly in relation to cellular redox homeostasis and related signalling under optimal and stress conditions. Here we outline the key recent advances and discuss how alterations in glutathione status, such as those observed during stress, may participate in signal transduction cascades. The discussion highlights some of the issues surrounding the regulation of glutathione contents, the control of glutathione redox potential, and how the functions of glutathione and other thiols are integrated to fine-tune photorespiratory and respiratory metabolism and to modulate phytohormone signalling pathways through appropriate modification of sensitive protein cysteine residues. © 2011 Blackwell Publishing Ltd.
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            Redox regulation in photosynthetic organisms: signaling, acclimation, and practical implications.

            Reactive oxygen species (ROS) have multifaceted roles in the orchestration of plant gene expression and gene-product regulation. Cellular redox homeostasis is considered to be an "integrator" of information from metabolism and the environment controlling plant growth and acclimation responses, as well as cell suicide events. The different ROS forms influence gene expression in specific and sometimes antagonistic ways. Low molecular antioxidants (e.g., ascorbate, glutathione) serve not only to limit the lifetime of the ROS signals but also to participate in an extensive range of other redox signaling and regulatory functions. In contrast to the low molecular weight antioxidants, the "redox" states of components involved in photosynthesis such as plastoquinone show rapid and often transient shifts in response to changes in light and other environmental signals. Whereas both types of "redox regulation" are intimately linked through the thioredoxin, peroxiredoxin, and pyridine nucleotide pools, they also act independently of each other to achieve overall energy balance between energy-producing and energy-utilizing pathways. This review focuses on current knowledge of the pathways of redox regulation, with discussion of the somewhat juxtaposed hypotheses of "oxidative damage" versus "oxidative signaling," within the wider context of physiological function, from plant cell biology to potential applications.
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              • Article: not found

              Understanding oxidative stress and antioxidant functions to enhance photosynthesis.

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                Author and article information

                Contributors
                Journal
                BMC Plant Biol
                BMC Plant Biol
                BMC Plant Biology
                BioMed Central
                1471-2229
                2013
                17 July 2013
                : 13
                : 104
                Affiliations
                [1 ]Department of Lothar Willmitzer, Max-Planck-Institute of Molecular Plant Physiology, Golm, 14476, Germany
                [2 ]Institute for Electron Microscopy and Fine Structure Research, Graz University of Technology, Steyrergasse 17, Graz, 8010, Austria
                [3 ]Institute of Plant Sciences, University of Graz, Schubertstrasse 51, Graz, 8010, Austria
                Article
                1471-2229-13-104
                10.1186/1471-2229-13-104
                3728233
                23865417
                782a95e9-beaa-43c5-bf97-b36918d5e819
                Copyright ©2013 Heyneke et al.; licensee BioMed Central Ltd.

                This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

                History
                : 3 April 2013
                : 16 July 2013
                Categories
                Research Article

                Plant science & Botany
                arabidopsis,ascorbate,chloroplast,glutathione,high light,reactive oxygen species

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