Baier, M. & Dietz, K. J. Chloroplasts as source and target of cellular redox regulation: a discussion on chloroplast redox signals in the context of plant physiology. J. Exp. Bot. 56, 1449-1462

Biochemistry and Physiology of Plants, University of Bielefeld, D-33501 Bielefeld, Germany.
Journal of Experimental Botany (Impact Factor: 5.53). 07/2005; 56(416):1449-62. DOI: 10.1093/jxb/eri161
Source: PubMed


During the evolution of plants, chloroplasts have lost the exclusive genetic control over redox regulation and antioxidant gene expression. Together with many other genes, all genes encoding antioxidant enzymes and enzymes involved in the biosynthesis of low molecular weight antioxidants were transferred to the nucleus. On the other hand, photosynthesis bears a high risk for photo-oxidative damage. Concomitantly, an intricate network for mutual regulation by anthero- and retrograde signals has emerged to co-ordinate the activities of the different genetic and metabolic compartments. A major focus of recent research in chloroplast regulation addressed the mechanisms of redox sensing and signal transmission, the identification of regulatory targets, and the understanding of adaptation mechanisms. In addition to redox signals communicated through signalling cascades also used in pathogen and wounding responses, specific chloroplast signals control nuclear gene expression. Signalling pathways are triggered by the redox state of the plastoquinone pool, the thioredoxin system, and the acceptor availability at photosystem I, in addition to control by oxolipins, tetrapyrroles, carbohydrates, and abscisic acid. The signalling function is discussed in the context of regulatory circuitries that control the expression of antioxidant enzymes and redox modulators, demonstrating the principal role of chloroplasts as the source and target of redox regulation.

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Available from: Margarete Baier
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    • "Despite intensive work, the signal molecule, which is responsible for transmitting information of the PQ pool redox state and which transduces that information into a regulatory mechanism that modulates the PSII antenna size, remains unknown. Among the chloroplast signals, reactive oxygen species and, in particular, hydrogen peroxide (H 2 O 2 ), play major roles in the different signalling pathways (Desikan et al., 2001; Vandenabeele et al., 2003; Apel and Hirt, 2004; Baier and Dietz, 2005; Vanderauwera et al., 2005; Slesak et al., 2007; Foyer and Noctor, 2009; Alboresi et al., 2011; Ivanov et al., 2012; Karpinski et al., 2013). In chloroplasts, the photochemical reactions are coupled to the generation of H 2 O 2 resulting from the reduction of molecular oxygen by the components of the photosynthetic electron transport chain (Mehler, 1951). "
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    ABSTRACT: Higher plants possess the ability to trigger a long-term acclimatory response to different environmental light conditions through the regulation of the light-harvesting antenna size of photosystem II. The present study provides an insight into the molecular nature of the signal which initiates the high light-mediated response of a reduction in antenna size. Using barley (Hordeum vulgare) plants, it is shown (i) that the light-harvesting antenna size is not reduced in high light with a low hydrogen peroxide content in the leaves; and (ii) that a decrease in the antenna size is observed in low light in the presence of an elevated concentration of hydrogen peroxide in the leaves. In particular, it has been demonstrated that the ability to reduce the antenna size of photosystem II in high light is restricted to photosynthetic apparatus with a reduced level of the plastoquinone pool and with a low hydrogen peroxide content. Conversely, the reduction of antenna size in low light is induced in photosynthetic apparatus possessing elevated hydrogen peroxide even when the reduction level of the plastoquinone pool is low. Hydrogen peroxide affects the relative abundance of the antenna proteins that modulate the antenna size of photosystem II through a down-regulation of the corresponding lhcb mRNA levels. This work shows that hydrogen peroxide contributes to triggering the photosynthetic apparatus response for the reduction of the antenna size of photosystem II by being the molecular signal for the long-term acclimation of plants to high light. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email:
    Full-text · Article · Aug 2015 · Journal of Experimental Botany
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    • "The initial concept of retrograde signalling was based on plastid factors that are needed for full expression of the (chloro-)plastidic complement of nuclear genes (Hagemann and Börner, 1978). Later on, central regulators were proposed to control plastid-to-nucleus communication which include genome uncoupled 4 (GUN4), ABA insensitive 1 and 4 (ABI1 and ABI4), redox responsive transcription factor (RRTF), and the executer proteins EX1 and EX2, which mediate a response to acute toxic singlet oxygen doses (op den Camp et al., 2003; Baier and Dietz, 2005; Koussevitzky et al., 2007; Khandelwal et al., 2008; Giraud et al., 2009; Pfannschmidt, 2010). Figure 8 summarizes key processes and events in light acclimation as recently described (Oelze et al., 2012, 2014; Alsharafa et al., 2014; Vogel et al., 2014). "
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    ABSTRACT: Like no other chemical or physical parameter, the natural light environment of plants changes with high speed and jumps of enormous intensity. To cope with this variability, photosynthetic organisms have evolved sensing and response mechanisms that allow efficient acclimation. Most signals originate from the chloroplast itself. In addition to very fast photochemical regulation, intensive molecular communication is realized within the photosynthesizing cell, optimizing the acclimation process. Current research has opened up new perspectives on plausible but mostly unexpected complexity in signalling events, crosstalk, and process adjustments. Within seconds and minutes, redox states, levels of reactive oxygen species, metabolites, and hormones change and transmit information to the cytosol, modifying metabolic activity, gene expression, translation activity, and alternative splicing events. Signalling pathways on an intermediate time scale of several minutes to a few hours pave the way for long-term acclimation. Thereby, a new steady state of the transcriptome, proteome, and metabolism is realized within rather short time periods irrespective of the previous acclimation history to shade or sun conditions. This review provides a time line of events during six hours in the 'stressful' life of a plant. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email:
    Full-text · Article · Jan 2015 · Journal of Experimental Botany
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    • "A decline or rise in the growth temperature from the optimal temperature resulted in an oxidative cellular environment as indicated by the decreased GSH/GSSG ratio, and this decrease was largely alleviated by grafting plants onto Cf or Lc (Fig. 6). Many enzymes (such as RCA and FBPase) involved in photosynthesis are redox-sensitive because the thiol-disulphide interchange is largely dependent on the redox state of the antioxidants (Daie 1993, Kim and Mayfield 1997, Baier and Dietz 2005). In cucumbers, CO 2 assimilation and the activities of these redox-sensitive enzymes are correlated with the GSH/GSSG ratio (Jiang et al. 2012). "
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    ABSTRACT: Shoot-root communication is involved in plant stress responses, but its mechanism is largely unknown. To determine the role of roots in stress tolerance, cucumber (Cucumis sativus) shoots from plants with roots of their own or with figleaf gourd (Cucurbita ficifolia, a chilling-tolerant species) or luffa (Luffa cylindrica (L.) M. Roem., a heat tolerant species) rootstocks were exposed to low (18/13 °C), optimal (27/22 °C) and high (36/31 °C) temperatures, respectively. Grafting onto figleaf gourd and luffa rootstocks significantly alleviated chilling and heat-induced reductions, respectively, in biomass production and CO2 assimilation capacity in the shoots, whilst levels of lipid peroxidation and protein oxidation were decreased. Figleaf gourd and luffa rootstocks upregulated a subset of stress-responsive genes involved in signal transduction (MAPK1 and RBOH), transcriptional regulation (MYB and MYC), protein protection (HSP45.9 and HSP70), the antioxidant response (Cu/Zn-SOD, cAPX, and GR), and photosynthesis (RBCL, RBCS, RCA, and FBPase) at low and high growth temperatures, respectively, and this was accompanied by increased activity of the encoded enzymes and reduced glutathione redox homeostasis in the leaves. Moreover, HSP70 expression in cucumber leaves was strongly induced by the luffa rootstock at the high growth temperature but slightly induced by the figleaf gourd rootstock at low or high growth temperatures. These results indicate that rootstocks could induce significant changes in the transcripts of stress-responsive and defense-related genes, and the ROS scavenging activity via unknown signals, especially at stressful growth temperatures, and this is one of mechanisms involved in the grafting-induced stress tolerance.
    Full-text · Article · Mar 2014 · Physiologia Plantarum
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