Article

Chloroplast redox control of nuclear gene expression--a new class of plastid signals in interorganellar communication.

Institute of General Botany, Department of Plant Physiology, University of Jena, Jena, Germany.
Antioxidants and Redox Signaling (Impact Factor: 7.67). 03/2003; 5(1):95-101. DOI: 10.1089/152308603321223586
Source: PubMed

ABSTRACT Chloroplasts are genetically semiautonomous organelles that contain their own subset of 100-120 genes coding for chloroplast proteins, tRNAs, and rRNAs. However, the great majority of the chloroplast proteins are encoded in the nucleus and must be imported into the organelle after their translation in the cytosol. This arrangement requires a high degree of coordination between the gene expression machineries in chloroplasts and nucleus, which is achieved by a permanent exchange of information between both compartments. The existence of such coordinating signals has long been known; however, the underlying molecular mechanisms and signaling routes are not understood. The present data indicate that the expression of nuclear-encoded chloroplast proteins is coupled to the functional state of the chloroplasts. Photosynthesis, which is the major function of chloroplasts, plays a crucial role in this context. Changes in the reduction/oxidation (redox) state of components of the photosynthetic machinery act as signals, which regulate the expression of chloroplast proteins in both chloroplasts and nucleus and help to coordinate the expression both in compartments. Recent advances in understanding chloroplast redox regulation of nuclear gene expression are summarized, and the importance for intracellular signaling is discussed.

2 Followers
 · 
138 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Natural illumination conditions are highly variable and because of their sessile life style plants are forced to acclimate to them at cellular and molecular level. Changes in light intensity or quality induce changes in the reduction/oxidation (redox) state of the photosynthetic electron chain that act as trigger for compensatory acclimation responses comprising functional and structural adjustments of photosynthesis and metabolism. Such responses include redox-controlled changes in plant gene expression in nucleus and organelles. Here we describe a strategy for the identification of early redox-regulated genes (ERGs) in the nucleus of the model organism Arabidopsis thaliana which significantly respond 30 or 60 min after the generation of a reduction signal in the photosynthetic electron transport chain. By comparing the response of wild-type plants with that of the acclimation mutant stn7 we could specifically identify ERGs. The results reveal a significant impact of chloroplast redox signals on distinct nuclear gene groups including genes for the mitochondrial electron transport chain, tetrapyrrole biosynthesis, carbohydrate metabolism and signalling lipid synthesis. These expression profiles are clearly different from that observed in response to reduction of the photosynthetic electron transport (PET) by high light treatments. The identified ERGs, thus, are unique to redox imbalances in PET and were used for the analysis of potential redox-responsive cis-elements, trans-factors and chromosomal regulatory hot spots. The data identify a novel redox-responsive element and indicate extensive redox control at transcriptional and chromosomal levels that point to an unprecedented impact of redox signals on epigenetic processes. Copyright © 2015 The Author. Published by Elsevier Inc. All rights reserved.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Plants are the ultimate food source for humans, either directly or indirectly. Being sessile in nature, they are exposed to various biotic and abiotic stresses because of changing climate that adversely effects their growth and development. Contamination of heavy metals is one of the major abiotic stresses because of anthropogenic as well as natural factors which lead to increased toxicity and accumulation in plants. Arsenic is a naturally occurring metalloid toxin present in the earth crust. Due to its presence in terrestrial and aquatic environments, it effects the growth of plants. Plants can tolerate arsenic using several mechanisms like phytochelation, vacuole sequestration and activation of antioxidant defense systems. Several signaling mechanisms have evolved in plants that involve the use of proteins, calcium ions, hormones, reactive oxygen species and nitric oxide as signaling molecules to cope with arsenic toxicity. These mechanisms facilitate plants to survive under metal stress by activating their defense systems. The pathways by which these stress signals are perceived and responded is an unexplored area of research and there are lots of gaps still to be filled. A good understanding of these signaling pathways can help in raising the plants which can perform better in arsenic contaminated soil and water. In order to increase the survival of plants in contaminated areas there is a strong need to identify suitable gene targets that can be modified according to needs of the stakeholders using various biotechnological techniques. This review focuses on the signaling mechanisms of plants grown under arsenic stress and will give an insight of the different sensory systems in plants. Furthermore, it provides the knowledge about several pathways that can be exploited to develop plant cultivars which are resistant to arsenic stress or can reduce its uptake to minimize the risk of arsenic toxicity through food chain thus ensuring food security.
    Ecotoxicology and Environmental Safety 01/2015; 114C:126-133. DOI:10.1016/j.ecoenv.2015.01.017 · 2.48 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Plant cells are often exposed to oxidative cellular environments which result in the generation of toxic reactive oxygen species (ROS). In order to detoxify the harmful ROS, plants have evolved various strategies including their scavenging and antioxidant machinery. Plant cellscontain many enzymatic and non-enzymatic antioxidants which aid in removing the toxic oxygen molecules. Various antioxidant molecules localized within different cellular compartments play crucial role(s) during this process, which includes both redox-signalling and redox-homeostasis. The present review gives an overview of cellular oxidativeenvironment, redox signalling operative within a cell and contributions of major cellular organelles towards maintaining the redox homeostasis. Additionally, the importance of various antioxidant enzymes working in an orchestrated and coordinated manner within acell, to protect it from stress injury has been presented. We also present the state-of-the-art where transgenic approach has been used to improve stress tolerance in model and crop species by engineering one or more than one of these components of the ROS scavenging machinery.
    12/2014; 2. DOI:10.3389/fenvs.2014.00070

Full-text (2 Sources)

Download
266 Downloads
Available from
Jun 3, 2014