Article

Glutathione, photosynthesis and redox regulation of stress-responsive gene expression. Photosynth Res 86: 459-474

Department of Biological Sciences, University of Essex, Wivenhoe Park, CO4 3SQ Colchester, UK.
Photosynthesis Research (Impact Factor: 3.5). 01/2006; 86(3):459-74. DOI: 10.1007/s11120-005-8811-8
Source: PubMed

ABSTRACT

The ubiquitous antioxidant thiol tripeptide glutathione is present in millimolar concentrations in plant tissues and is regarded as one of the major determinants of cellular redox homeostasis. Recent research has highlighted a regulatory role for glutathione in influencing the expression of many genes important in plants' responses to both abiotic and biotic stress. Therefore, it becomes important to consider how glutathione levels and its redox state are influenced by environmental factors, how glutathione is integrated into primary metabolism and precisely how it can influence the functioning of signal transduction pathways by modulating cellular redox state. This review draws on a number of recent important observations and papers to present a unified view of how the responsiveness of glutathione to changes in photosynthesis may be one means of linking changes in nuclear gene expression to changes in the plant's external environment.

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    • "Crucial role of GSH in plant antioxidant defense typifies this compound as a stress marker. GSH provides the most important intracellular defense against ROS (Mullineaux and Rausch 2005). It also plays a central role in detoxification of xenobiotics as well as the expression of stressresponsive genes (Ding et al. 2007; Golisz et al. 2008; Sytykiewicz 2011). "
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    ABSTRACT: The current study was conducted to evaluate the physiological and molecular response of self-regenerating annual Medicago species (M. polymorpha and M. lupulina) to juglone exposure. A randomized complete block design was performed in which two treatment groups consisted of a control and juglone (10-4 M) allotted to main plots and genotypes assigned to subplots. A significant increase in the concentration of GSH and the GSH/ GSSG ratio was observed in both annual Medicago species in response to juglone exposure. However, such response was greater in M. lupulina than M. polymorpha. The activity of all antioxidant enzymes (CAT, APX, GST, and GPOX) was significantly increased by juglone. In response to juglone, the expression of WRKY was significantly decreased. The transcription of CBF4, Zpt2-2, CAT, and GST genes was highly induced by juglone in annual Medicago species. Higher expression of CBF4, Zpt2-2, CAT and GST genes in M. lupulina which showed more juglone-tolerance can be associated with higher tolerance against allelochemical stress. It can be concluded that M. polymorpha is juglone-sensitive because it started to show chlorosis of leaves after a week subjecting to juglone. Though M. lupulina seems to be more juglone-tolerant at least in short term, long-term exposure of juglone should also be examined to find out its suitability to grow in walnut orchards. Considering the presence of cross-talk between different stresses, we can propose that M. lupulina is more tolerant to other abiotic stresses compared to M. polymorpha.
    Full-text · Article · Nov 2015 · Acta Physiologiae Plantarum
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    • "FW, Fresh weight; E, EcoRI; H, HindIII. 2004; Mullineaux and Rausch, 2005; Liedschulte et al., 2010). Transgenic Arabidopsis plants with low GSH level (10% of the wild type) exhibit hypersensitivity to cadmium stress due to the limited capacity of these plants to make phytochelatins (Xiang et al., 2001). "
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    ABSTRACT: Glutathione (GSH) plays a fundamental role in plant defense signaling network. Recently, we have established the involvement of GSH with ethylene (ET) to combat environmental stress. However, the mechanism of GSH-ET interplay still remains unexplored. Here, we demonstrate that GSH induces ET biosynthesis by modulating the transcriptional and post-trancriptional regulations of its key enzymes, ACC synthase (ACS) and ACC oxidase (ACO). Transgenic Arabidopsis thaliana plants with enhanced GSH content (AtECS) exhibited remarkable up-regulation of ACS2, ACS6 and ACO1 at transcript as well as protein levels while they were down-regulated in the GSH depleted pad2-1 mutant. We further observed that GSH induced ACS2 and ACS6 transcription in a WRKY33 dependent manner while ACO1 transcription remained unaffected. On the other hand, the mRNA stability for ACO1 was found to be increased by GSH which explains our above observations. In addition, we also identified the ACO1 protein to be a subject for S-glutathionylation which is consistent with our in silico data. However, S-glutathionylation of ACS2 and ACS6 proteins was not detected. Further, the AtECS plants exhibited resistance to necrotrophic infection and salt stress while the pad2-1 mutant was sensitive. Exogenously applied GSH could improve stress tolerance in wild-type plants but not in the ET signaling mutant, ein2-1, indicating that GSH mediated resistance to these stresses occurs via an ET mediated pathway. Together, our investigation reveals a dual-level regulation of ET biosynthesis by GSH during stress.
    Preview · Article · Oct 2015 · Plant physiology
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    • "It can also act as scavenger for hydroxyl radical, singlet O2 and various electrophiles. Recent research has highlight a regulatory role of glutathione is influencing the expression of many gene which are important in the plant responses to both abiotic and biotic stress (Mullineaux et al., 2005). GR play an important role in metabolism and it is also involved in the detoxification of xenobiotic and protection against heavy metal toxicity as a source of reductant in enzyme reaction (Mohammad et al., 2012). "
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    ABSTRACT: Glutathione reductase (GR) is an essential enzyme which plays an important role in the Ascorbate Glutathione metabolic pathway for the oxidative tolerance in plants. It acts as an anti-oxidant enzyme preserving a reduced intracellular environment and protection of cellular macromolecules like DNA, proteins and lipids. During exposure to the biotic stresses, the differential modulation of GR in plants has been widely implicated in the significance of antioxidants as the major components of plant defense operations. How the stress factor affects the plant leaves and what is the role of GR as a defense mechanism to protect the plants from these stresses, will be studied in this review in a gross detail. This review lays emphasis on the overview about structure, localization, biosynthesis and mechanism of GR from the abiotic stress for exposed crop plants and also points-out unexplored aspects in the current context. It draws inspiration from a number of observations and research papers by scientists across the molecular biology world to understand and assert that GR is a vital enzyme without which a plant's survival is difficult and impossible. We hope that this review would enlighten the reader to think broadly about the plant's life cycle and importance of GR as a performance enhancing-agent in plants to help maintain the balance between plant and animals in the environment.
    Full-text · Article · Aug 2015
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