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Ferrari M, Marieschi M, Cozza R, Torelli A. Phytochelatin Synthase: An In Silico Comparative Analysis in Cyanobacteria and Eukaryotic Microalgae. PLANTS (BASEL, SWITZERLAND) 2024; 13:2165. [PMID: 39124283 PMCID: PMC11314372 DOI: 10.3390/plants13152165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2024] [Revised: 07/09/2024] [Accepted: 08/01/2024] [Indexed: 08/12/2024]
Abstract
Phytochelatins (PCs) are small cysteine-rich peptides involved in metal detoxification, not genetically encoded but enzymatically synthesized by phytochelatin synthases (PCSs) starting from glutathione. The constitutive PCS expression even in the absence of metal contamination, the wide phylogenetic distribution and the similarity between PCSs and the papain-type cysteine protease catalytic domain suggest a wide range of functions for PCSs. These proteins, widely studied in land plants, have not been fully analyzed in algae and cyanobacteria, although these organisms are the first to cope with heavy-metal stress in aquatic environments and can be exploited for phytoremediation. To fill this gap, we compared the features of the PCS proteins of different cyanobacterial and algal taxa by phylogenetic linkage. The analyzed sequences fall into two main, already known groups of PCS-like proteins. Contrary to previous assumptions, they are not classed as prokaryotic and eukaryotic sequences, but rather as sequences characterized by the alternative presence of asparagine and aspartic/glutamic acid residues in proximity of the catalytic cysteine. The presence of these enzymes with peculiar features suggests differences in their post-translational regulation related to cell/environmental requirements or different cell functions rather than to differences due to their belonging to different phylogenetic taxa.
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Affiliation(s)
- Michele Ferrari
- Department of Biology, Ecology and Earth Science, University of Calabria, Arcavacata di Rende, 87036 Cosenza, Italy; (M.F.); (R.C.)
| | - Matteo Marieschi
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Viale delle Scienze 11/A, 43124 Parma, Italy;
| | - Radiana Cozza
- Department of Biology, Ecology and Earth Science, University of Calabria, Arcavacata di Rende, 87036 Cosenza, Italy; (M.F.); (R.C.)
| | - Anna Torelli
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Viale delle Scienze 11/A, 43124 Parma, Italy;
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2
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Sun SK, Chen J, Zhao FJ. Regulatory mechanisms of sulfur metabolism affecting tolerance and accumulation of toxic trace metals and metalloids in plants. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:3286-3299. [PMID: 36861339 DOI: 10.1093/jxb/erad074] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 02/23/2023] [Indexed: 06/08/2023]
Abstract
Soil contamination with trace metals and metalloids can cause toxicity to plants and threaten food safety and human health. Plants have evolved sophisticated mechanisms to cope with excess trace metals and metalloids in soils, including chelation and vacuolar sequestration. Sulfur-containing compounds, such as glutathione and phytochelatins, play a crucial role in their detoxification, and sulfur uptake and assimilation are regulated in response to the stress of toxic trace metals and metalloids. This review focuses on the multi-level connections between sulfur homeostasis in plants and responses to such stresses, especially those imposed by arsenic and cadmium. We consider recent progress in understanding the regulation of biosynthesis of glutathione and phytochelatins and of the sensing mechanism of sulfur homeostasis for tolerance of trace metals and metalloids in plants. We also discuss the roles of glutathione and phytochelatins in controlling the accumulation and distribution of arsenic and cadmium in plants, and possible strategies for manipulating sulfur metabolism to limit their accumulation in food crops.
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Affiliation(s)
- Sheng-Kai Sun
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
- Centre for Organismal Studies (COS), Heidelberg University, 69120 Heidelberg, Germany
| | - Jie Chen
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Fang-Jie Zhao
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
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3
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Ito T, Ohkama-Ohtsu N. Degradation of glutathione and glutathione conjugates in plants. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:3313-3327. [PMID: 36651789 DOI: 10.1093/jxb/erad018] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 01/12/2023] [Indexed: 06/08/2023]
Abstract
Glutathione (GSH) is a ubiquitous, abundant, and indispensable thiol for plants that participates in various biological processes, such as scavenging reactive oxygen species, redox signaling, storage and transport of sulfur, detoxification of harmful substances, and metabolism of several compounds. Therefore knowledge of GSH metabolism is essential for plant science. Nevertheless, GSH degradation has been insufficiently elucidated, and this has hampered our understanding of plant life. Over the last five decades, the γ-glutamyl cycle has been dominant in GSH studies, and the exoenzyme γ-glutamyl transpeptidase has been regarded as the major GSH degradation enzyme. However, recent studies have shown that GSH is degraded in cells by cytosolic enzymes such as γ-glutamyl cyclotransferase or γ-glutamyl peptidase. Meanwhile, a portion of GSH is degraded after conjugation with other molecules, which has also been found to be carried out by vacuolar γ-glutamyl transpeptidase, γ-glutamyl peptidase, or phytochelatin synthase. These findings highlight the need to re-assess previous assumptions concerning the γ-glutamyl cycle, and a novel overview of the plant GSH degradation pathway is essential. This review aims to build a foundation for future studies by summarizing current understanding of GSH/glutathione conjugate degradation.
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Affiliation(s)
- Takehiro Ito
- United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, 3-5-8, Saiwai-cho, Fuchu, Tokyo, 183-8509, Japan
- RIKEN Center for Sustainable Resource Science, 1-7-22, Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan
| | - Naoko Ohkama-Ohtsu
- Institute of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8, Saiwai-cho, Fuchu, Tokyo, 183-8509, Japan
- Institute of Global Innovation Research, Tokyo University of Agriculture and Technology, 3-5-8, Saiwai-cho, Fuchu, Tokyo, 183-8509, Japan
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4
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Burns AR, Baker RJ, Kitner M, Knox J, Cooke B, Volpatti JR, Vaidya AS, Puumala E, Palmeira BM, Redman EM, Snider J, Marwah S, Chung SW, MacDonald MH, Tiefenbach J, Hu C, Xiao Q, Finney CAM, Krause HM, MacParland SA, Stagljar I, Gilleard JS, Cowen LE, Meyer SLF, Cutler SR, Dowling JJ, Lautens M, Zasada I, Roy PJ. Selective control of parasitic nematodes using bioactivated nematicides. Nature 2023:10.1038/s41586-023-06105-5. [PMID: 37225985 DOI: 10.1038/s41586-023-06105-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 04/20/2023] [Indexed: 05/26/2023]
Abstract
Parasitic nematodes are a major threat to global food security, particularly as the world amasses 10 billion people amid limited arable land1-4. Most traditional nematicides have been banned owing to poor nematode selectivity, leaving farmers with inadequate means of pest control4-12. Here we use the model nematode Caenorhabditis elegans to identify a family of selective imidazothiazole nematicides, called selectivins, that undergo cytochrome-p450-mediated bioactivation in nematodes. At low parts-per-million concentrations, selectivins perform comparably well with commercial nematicides to control root infection by Meloidogyne incognita, a highly destructive plant-parasitic nematode. Tests against numerous phylogenetically diverse non-target systems demonstrate that selectivins are more nematode-selective than most marketed nematicides. Selectivins are first-in-class bioactivated nematode controls that provide efficacy and nematode selectivity.
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Affiliation(s)
- Andrew R Burns
- The Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada.
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada.
| | - Rachel J Baker
- Davenport Research Laboratories, Department of Chemistry, University of Toronto, Toronto, Ontario, Canada
| | - Megan Kitner
- USDA-ARS Horticultural Crops Research Laboratory, Corvallis, OR, USA
| | - Jessica Knox
- The Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Brittany Cooke
- The Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Jonathan R Volpatti
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- Division of Neurology and Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Aditya S Vaidya
- Institute for Integrative Genome Biology, University of California, Riverside, Riverside, CA, USA
- Department of Botany and Plant Sciences, University of California, Riverside, Riverside, CA, USA
| | - Emily Puumala
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Bruna M Palmeira
- Department of Comparative Biology and Experimental Medicine, Host-Parasite Interactions Program, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Elizabeth M Redman
- Department of Comparative Biology and Experimental Medicine, Host-Parasite Interactions Program, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Jamie Snider
- The Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
| | - Sagar Marwah
- Ajmera Transplant Centre, Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology and Immunology, University of Toronto, Toronto, Ontario, Canada
| | - Sai W Chung
- Ajmera Transplant Centre, Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology and Immunology, University of Toronto, Toronto, Ontario, Canada
| | - Margaret H MacDonald
- USDA-ARS Mycology and Nematology Genetic Diversity and Biology Laboratory, Beltsville Agricultural Research Center, Beltsville, MD, USA
| | - Jens Tiefenbach
- The Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
| | - Chun Hu
- The Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Qi Xiao
- Department of Biological Sciences, Host Parasite Interactions Program, Faculty of Science, University of Calgary, Calgary, Alberta, Canada
| | - Constance A M Finney
- Department of Biological Sciences, Host Parasite Interactions Program, Faculty of Science, University of Calgary, Calgary, Alberta, Canada
| | - Henry M Krause
- The Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Sonya A MacParland
- Ajmera Transplant Centre, Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology and Immunology, University of Toronto, Toronto, Ontario, Canada
| | - Igor Stagljar
- The Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
- Mediterranean Institute for Life Sciences, Split, Croatia
| | - John S Gilleard
- Department of Comparative Biology and Experimental Medicine, Host-Parasite Interactions Program, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Leah E Cowen
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Susan L F Meyer
- USDA-ARS Mycology and Nematology Genetic Diversity and Biology Laboratory, Beltsville Agricultural Research Center, Beltsville, MD, USA
| | - Sean R Cutler
- Institute for Integrative Genome Biology, University of California, Riverside, Riverside, CA, USA
- Department of Botany and Plant Sciences, University of California, Riverside, Riverside, CA, USA
| | - James J Dowling
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- Division of Neurology and Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Mark Lautens
- Davenport Research Laboratories, Department of Chemistry, University of Toronto, Toronto, Ontario, Canada
| | - Inga Zasada
- USDA-ARS Horticultural Crops Research Laboratory, Corvallis, OR, USA
| | - Peter J Roy
- The Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada.
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada.
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada.
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5
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Dard A, Weiss A, Bariat L, Auverlot J, Fontaine V, Picault N, Pontvianne F, Riondet C, Reichheld JP. Glutathione-mediated thermomorphogenesis and heat stress responses in Arabidopsis thaliana. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:2707-2725. [PMID: 36715641 DOI: 10.1093/jxb/erad042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 01/28/2023] [Indexed: 06/06/2023]
Abstract
In the context of climate change, the global rise of temperature and intense heat waves affect plant development and productivity. Among the molecular perturbations that high temperature induces in living cells is the accumulation of reactive oxygen species (ROS), which perturbs the cellular redox state. In plants, the dynamics of the cellular and subcellular redox state have been poorly investigated under high temperature. Glutathione plays a major role in maintaining the cellular redox state. We investigated its contribution in adaptation of Arabidopsis thaliana to contrasting high temperature regimes: high ambient temperature inducing thermomorphogenesis and heat stress affecting plant viability. Using the genetically encoded redox marker roGFP2, we show that high temperature regimes lead to cytoplasmic and nuclear oxidation and impact the glutathione pool. This pool is restored within a few hours, which probably contributes to plant adaptation to high temperatures. Moreover, low glutathione mutants fail to adapt to heat stress and to induce thermomorphogenesis, suggesting that glutathione is involved in both heat adaptation mechanisms. We also evaluate the transcriptomic signature in the two high temperature regimes and identified gene expression deviations in low glutathione mutants, which might contribute to their sensitivity to high temperature. Thus, we define glutathione as a major player in the adaptation of Arabidopsis to contrasting high temperature regimes.
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Affiliation(s)
- Avilien Dard
- Laboratoire Génome et Développement des Plantes, Université Perpignan Via Domitia, F-66860 Perpignan, France
- Laboratoire Génome et Développement des Plantes, CNRS, F-66860 Perpignan, France
| | - Alizée Weiss
- Laboratoire Génome et Développement des Plantes, Université Perpignan Via Domitia, F-66860 Perpignan, France
- Laboratoire Génome et Développement des Plantes, CNRS, F-66860 Perpignan, France
| | - Laetitia Bariat
- Laboratoire Génome et Développement des Plantes, Université Perpignan Via Domitia, F-66860 Perpignan, France
- Laboratoire Génome et Développement des Plantes, CNRS, F-66860 Perpignan, France
| | - Juline Auverlot
- Laboratoire Génome et Développement des Plantes, Université Perpignan Via Domitia, F-66860 Perpignan, France
- Laboratoire Génome et Développement des Plantes, CNRS, F-66860 Perpignan, France
| | - Valentine Fontaine
- Laboratoire Génome et Développement des Plantes, Université Perpignan Via Domitia, F-66860 Perpignan, France
- Laboratoire Génome et Développement des Plantes, CNRS, F-66860 Perpignan, France
| | - Nathalie Picault
- Laboratoire Génome et Développement des Plantes, Université Perpignan Via Domitia, F-66860 Perpignan, France
- Laboratoire Génome et Développement des Plantes, CNRS, F-66860 Perpignan, France
| | - Frédéric Pontvianne
- Laboratoire Génome et Développement des Plantes, Université Perpignan Via Domitia, F-66860 Perpignan, France
- Laboratoire Génome et Développement des Plantes, CNRS, F-66860 Perpignan, France
| | - Christophe Riondet
- Laboratoire Génome et Développement des Plantes, Université Perpignan Via Domitia, F-66860 Perpignan, France
- Laboratoire Génome et Développement des Plantes, CNRS, F-66860 Perpignan, France
| | - Jean-Philippe Reichheld
- Laboratoire Génome et Développement des Plantes, Université Perpignan Via Domitia, F-66860 Perpignan, France
- Laboratoire Génome et Développement des Plantes, CNRS, F-66860 Perpignan, France
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6
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Seregin IV, Kozhevnikova AD. Phytochelatins: Sulfur-Containing Metal(loid)-Chelating Ligands in Plants. Int J Mol Sci 2023; 24:2430. [PMID: 36768751 PMCID: PMC9917255 DOI: 10.3390/ijms24032430] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 01/20/2023] [Accepted: 01/23/2023] [Indexed: 01/28/2023] Open
Abstract
Phytochelatins (PCs) are small cysteine-rich peptides capable of binding metal(loid)s via SH-groups. Although the biosynthesis of PCs can be induced in vivo by various metal(loid)s, PCs are mainly involved in the detoxification of cadmium and arsenic (III), as well as mercury, zinc, lead, and copper ions, which have high affinities for S-containing ligands. The present review provides a comprehensive account of the recent data on PC biosynthesis, structure, and role in metal(loid) transport and sequestration in the vacuoles of plant cells. A comparative analysis of PC accumulation in hyperaccumulator plants, which accumulate metal(loid)s in their shoots, and in the excluders, which accumulate metal(loid)s in their roots, investigates the question of whether the endogenous PC concentration determines a plant's tolerance to metal(loid)s. Summarizing the available data, it can be concluded that PCs are not involved in metal(loid) hyperaccumulation machinery, though they play a key role in metal(loid) homeostasis. Unraveling the physiological role of metal(loid)-binding ligands is a fundamental problem of modern molecular biology, plant physiology, ionomics, and toxicology, and is important for the development of technologies used in phytoremediation, biofortification, and phytomining.
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Affiliation(s)
- Ilya V. Seregin
- K.A. Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya St., 35, 127276 Moscow, Russia
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7
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Gu TY, Qi ZA, Chen SY, Yan J, Fang ZJ, Wang JM, Gong JM. Dual-function DEFENSIN 8 mediates phloem cadmium unloading and accumulation in rice grains. PLANT PHYSIOLOGY 2023; 191:515-527. [PMID: 36087013 PMCID: PMC9806624 DOI: 10.1093/plphys/kiac423] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 08/15/2022] [Indexed: 06/01/2023]
Abstract
Grain cadmium (Cd) is translocated from source to sink tissues exclusively via phloem, though the phloem Cd unloading transporter has not been identified yet. Here, we isolated and functionally characterized a defensin-like gene DEFENSIN 8 (DEF8) highly expressed in rice (Oryza sativa) grains and induced by Cd exposure in seedling roots. Histochemical analysis and subcellular localization detected DEF8 expression preferentially in pericycle cells and phloem of seedling roots, as well as in phloem of grain vasculatures. Further analysis demonstrated that DEF8 is secreted into extracellular spaces possibly by vesicle trafficking. DEF8 bound to Cd in vitro, and Cd efflux from protoplasts as well as loading into xylem vessels decreased in the def8 mutant seedlings compared with the wild type. At maturity, significantly less Cd accumulation was observed in the mutant grains. These results suggest that DEF8 is a dual function protein that facilitates Cd loading into xylem and unloading from phloem, thus mediating Cd translocation from roots to shoots and further allocation to grains, representing a phloem Cd unloading regulator. Moreover, essential mineral nutrient accumulation as well as important agronomic traits were not affected in the def8 mutants, suggesting DEF8 is an ideal target for breeding low grain Cd rice.
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Affiliation(s)
| | | | - Si-Ying Chen
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Jing Yan
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng 475004, China
| | - Zi-Jun Fang
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Jun-Min Wang
- Institute of Crops and Nuclear Technology Utilization, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
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8
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Inoue R, Nakamura N, Matsumoto C, Takase H, Sekiya J, Prieto R. Characterization of γ-glutamyltransferase- and phytochelatin synthase-mediated catabolism of glutathione and glutathione S-conjugates in Arabidopsis thaliana. PLANT BIOTECHNOLOGY (TOKYO, JAPAN) 2022; 39:381-389. [PMID: 37283618 PMCID: PMC10240914 DOI: 10.5511/plantbiotechnology.22.1003a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 10/03/2022] [Indexed: 06/08/2023]
Abstract
Glutathione (GSH, γ-L-glutamyl-L-cysteinyl-glycine) has been implicated in a multitude of cellular functions, such as protection of cells against oxidative stress, detoxification of xenobiotics via degradation of GSH S-conjugates, and disease resistance. Glutathione also serves as a precursor of phytochelatins, and thereby plays an essential role in heavy metal detoxification. The Arabidopsis genome encodes three functional γ-glutamyltransferase genes (AtGGT1, AtGGT2, AtGGT4) and two phytochelatin synthase genes (AtPCS1, AtPCS2). The function of plant GGT has not yet been clearly defined, although it is thought to be involved in GSH and GSH S-conjugate catabolism. On the other hand, besides its role in heavy metal detoxification, PCS has also been involved in GSH S-conjugate catabolism. Herein we describe the HPLC characterization of GSH and GSH S-conjugate catabolism in Arabidopsis mutants deficient in GSH biosynthesis (pad2-1/gsh1), atggt and atpcs1 T-DNA insertion mutants, atggt pad2-1, atggt atpcs1 double mutants, and the atggt1 atggt4 atpcs1 triple mutant. The results of our HPLC analysis confirm that AtGGT and AtPCS play important roles in two different pathways related with GSH and GSH S-conjugate (GS-bimane) catabolism in Arabidopsis.
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Affiliation(s)
- Ryota Inoue
- Department of Bioscience and Biotechnology, Faculty of Bioenvironmental Science, Kyoto University of Advanced Science, 1-1 Nanjo, Sogabe-cho, Kameoka, Kyoto 621-8555, Japan
| | - Naoto Nakamura
- Department of Bioscience and Biotechnology, Faculty of Bioenvironmental Science, Kyoto University of Advanced Science, 1-1 Nanjo, Sogabe-cho, Kameoka, Kyoto 621-8555, Japan
| | - Chie Matsumoto
- Department of Bioscience and Biotechnology, Faculty of Bioenvironmental Science, Kyoto University of Advanced Science, 1-1 Nanjo, Sogabe-cho, Kameoka, Kyoto 621-8555, Japan
| | - Hisabumi Takase
- Department of Bioscience and Biotechnology, Faculty of Bioenvironmental Science, Kyoto University of Advanced Science, 1-1 Nanjo, Sogabe-cho, Kameoka, Kyoto 621-8555, Japan
| | - Jiro Sekiya
- Department of Bioscience and Biotechnology, Faculty of Bioenvironmental Science, Kyoto University of Advanced Science, 1-1 Nanjo, Sogabe-cho, Kameoka, Kyoto 621-8555, Japan
| | - Rafael Prieto
- Department of Bioscience and Biotechnology, Faculty of Bioenvironmental Science, Kyoto University of Advanced Science, 1-1 Nanjo, Sogabe-cho, Kameoka, Kyoto 621-8555, Japan
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9
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Effects of Phytochelatin-like Gene on the Resistance and Enrichment of Cd 2+ in Tobacco. Int J Mol Sci 2022; 23:ijms232416167. [PMID: 36555808 PMCID: PMC9784533 DOI: 10.3390/ijms232416167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 12/13/2022] [Accepted: 12/16/2022] [Indexed: 12/23/2022] Open
Abstract
Phytochelatins (PCs) are class III metallothioneins in plants. They are low molecular-weight polypeptides rich in cysteine residues which can bind to metal ions and affect the physiological metabolism in plants. Unlike other types of metallothioneins, PCs are not the product of gene coding but are synthesized by phytochelatin synthase (PCS) based on glutathione (GSH). The chemical formula of phytochelatin is a mixture of (γ-Glu-Cys)n-Gly (n = 2-11) and is influenced by many factors during synthesis. Phytochelatin-like (PCL) is a gene-encoded peptide (Met-(α-Glu-Cys)11-Gly) designed by our laboratory whose amino acid sequence mimics that of a natural phytochelatin. This study investigated how PCL expression in transgenic plants affects resistance to Cd and Cd accumulation. Under Cd2+ stress, transgenic plants were proven to perform significantly better than the wild-type (WT), regarding morphological traits and antioxidant abilities, but accumulated Cd to higher levels, notably in the roots. Fluorescence microscopy showed that PCL localized in the cytoplasm and nucleus.
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10
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Uraguchi S, Ohshiro Y, Otsuka Y, Wada E, Naruse F, Sugaya K, Nagai K, Wongkaew A, Nakamura R, Takanezawa Y, Clemens S, Ohkama-Ohtsu N, Kiyono M. Phytochelatin-mediated metal detoxification pathway is crucial for an organomercurial phenylmercury tolerance in Arabidopsis. PLANT MOLECULAR BIOLOGY 2022; 109:563-577. [PMID: 34837578 DOI: 10.1007/s11103-021-01221-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 11/16/2021] [Indexed: 06/13/2023]
Abstract
An organomercurial phenylmercury activates AtPCS1, an enzyme known for detoxification of inorganic metal(loid) ions in Arabidopsis and the induced metal-chelating peptides phytochelatins are essential for detoxification of phenylmercury. Small thiol-rich peptides phytochelatins (PCs) and their synthases (PCSs) are crucial for plants to mitigate the stress derived from various metal(loid) ions in their inorganic form including inorganic mercury [Hg(II)]. However, the possible roles of the PC/PCS system in organic mercury detoxification in plants remain elusive. We found that an organomercury phenylmercury (PheHg) induced PC synthesis in Arabidopsis thaliana plants as Hg(II), whereas methylmercury did not. The analyses of AtPCS1 mutant plants and in vitro assays using the AtPCS1-recombinant protein demonstrated that AtPCS1, the major PCS in A. thaliana, was responsible for the PheHg-responsive PC synthesis. AtPCS1 mutants cad1-3 and cad1-6, and the double mutant of PC-metal(loid) complex transporters AtABCC1 and AtABCC2 showed enhanced sensitivity to PheHg as well as to Hg(II). The hypersensitivity of cad1-3 to PheHg stress was complemented by the own-promoter-driven expression of AtPCS1-GFP. The confocal microscopy of the complementation lines showed that the AtPCS1-GFP was preferentially expressed in epidermal cells of the mature and elongation zones, and the outer-most layer of the lateral root cap cells in the meristematic zone. Moreover, in vitro PC-metal binding assay demonstrated that binding affinity between PC and PheHg was comparable to Hg(II). However, plant ionomic profiles, as well as root morphology under PheHg and Hg(II) stress, were divergent. These results suggest that PheHg phytotoxicity is different from Hg(II), but AtPCS1-mediated PC synthesis, complex formation, and vacuolar sequestration by AtABCC1 and AtABCC2 are similarly functional for both PheHg and Hg(II) detoxification in root surficial cell types.
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Affiliation(s)
- Shimpei Uraguchi
- Department of Public Health, School of Pharmacy, Kitasato University, Minato-ku, Tokyo, 108-8641, Japan.
| | - Yuka Ohshiro
- Department of Public Health, School of Pharmacy, Kitasato University, Minato-ku, Tokyo, 108-8641, Japan
| | - Yuto Otsuka
- Department of Public Health, School of Pharmacy, Kitasato University, Minato-ku, Tokyo, 108-8641, Japan
| | - Emiko Wada
- Department of Public Health, School of Pharmacy, Kitasato University, Minato-ku, Tokyo, 108-8641, Japan
| | - Fumii Naruse
- Department of Public Health, School of Pharmacy, Kitasato University, Minato-ku, Tokyo, 108-8641, Japan
| | - Kakeru Sugaya
- Department of Public Health, School of Pharmacy, Kitasato University, Minato-ku, Tokyo, 108-8641, Japan
| | - Kenichiro Nagai
- Medicinal Research Laboratories, School of Pharmacy, Kitasato University, Minato-ku, Tokyo, 108-8641, Japan
| | - Arunee Wongkaew
- United Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo, 183-8509, Japan
- Department of Agronomy, Faculty of Agriculture, Kasetsart University, Bangkok, 10900, Thailand
| | - Ryosuke Nakamura
- Department of Public Health, School of Pharmacy, Kitasato University, Minato-ku, Tokyo, 108-8641, Japan
| | - Yasukazu Takanezawa
- Department of Public Health, School of Pharmacy, Kitasato University, Minato-ku, Tokyo, 108-8641, Japan
| | - Stephan Clemens
- Department of Plant Physiology, Bayreuth Center of Ecology and Environmental Research, University of Bayreuth, 95447, Bayreuth, Germany
| | - Naoko Ohkama-Ohtsu
- Institute of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo, 183-8509, Japan
- Institute of Global Innovation Research, Tokyo University of Agriculture and Technology, Fuchu, Tokyo, 183-8509, Japan
| | - Masako Kiyono
- Department of Public Health, School of Pharmacy, Kitasato University, Minato-ku, Tokyo, 108-8641, Japan.
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11
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Seregin IV, Kozhevnikova AD. Low-molecular-weight ligands in plants: role in metal homeostasis and hyperaccumulation. PHOTOSYNTHESIS RESEARCH 2021; 150:51-96. [PMID: 32653983 DOI: 10.1007/s11120-020-00768-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 06/22/2020] [Indexed: 06/11/2023]
Abstract
Mineral nutrition is one of the key factors determining plant productivity. In plants, metal homeostasis is achieved through the functioning of a complex system governing metal uptake, translocation, distribution, and sequestration, leading to the maintenance of a regulated delivery of micronutrients to metal-requiring processes as well as detoxification of excess or non-essential metals. Low-molecular-weight ligands, such as nicotianamine, histidine, phytochelatins, phytosiderophores, and organic acids, play an important role in metal transport and detoxification in plants. Nicotianamine and histidine are also involved in metal hyperaccumulation, which determines the ability of some plant species to accumulate a large amount of metals in their shoots. In this review we extensively summarize and discuss the current knowledge of the main pathways for the biosynthesis of these ligands, their involvement in metal uptake, radial and long-distance transport, as well as metal influx, isolation and sequestration in plant tissues and cell compartments. It is analyzed how diverse endogenous ligand levels in plants can determine their different tolerance to metal toxic effects. This review focuses on recent advances in understanding the physiological role of these compounds in metal homeostasis, which is an essential task of modern ionomics and plant physiology. It is of key importance in studying the influence of metal deficiency or excess on various physiological processes, which is a prerequisite to the improvement of micronutrient uptake efficiency and crop productivity and to the development of a variety of applications in phytoremediation, phytomining, biofortification, and nutritional crop safety.
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Affiliation(s)
- I V Seregin
- K.A. Timiryazev Institute of Plant Physiology RAS, IPPRAS, Botanicheskaya st., 35, Moscow, Russian Federation, 127276.
| | - A D Kozhevnikova
- K.A. Timiryazev Institute of Plant Physiology RAS, IPPRAS, Botanicheskaya st., 35, Moscow, Russian Federation, 127276
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12
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Uraguchi S, Ohshiro Y, Otsuka Y, Tsukioka H, Yoneyama N, Sato H, Hirakawa M, Nakamura R, Takanezawa Y, Kiyono M. Selection of Agar Reagents for Medium Solidification Is a Critical Factor for Metal(loid) Sensitivity and Ionomic Profiles of Arabidopsis thaliana. FRONTIERS IN PLANT SCIENCE 2020; 11:503. [PMID: 32499794 PMCID: PMC7243937 DOI: 10.3389/fpls.2020.00503] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 04/03/2020] [Indexed: 06/11/2023]
Abstract
For researchers in the plant metal field, the agar reagent used for the solid plate medium is a problematic factor because application of different agar types and even a different lot of the same agar type can mask the plant metal-related phenotypes and impair the reproducibility. In this study, we systematically assessed effects of different agar reagents on metal(loid) sensitivity and element accumulation of the Arabidopsis metal sensitive mutants. Three established mutants (cad1-3, cad1-6, and abcc1/2), and three different types of purified agar reagents (Type A, Type E, and Nacalai) with two independent batches for each reagent were subjected to the analyses. First, we found that element concentrations in the agar reagents largely varied among the agar types. Then the effects of agar reagents on the mutant metal(loid)-sensitivity were examined under As(III), Hg(II), Cd(II), and excess Zn(II) conditions. A significant variation of the mutant metal(loid)-sensitivity was observed among the different agar plates but the variation depended on the combination of metal(loid) stress and agar reagents. Briefly, the type-dependent variation was more evident under As(III) and Hg(II) than Cd(II) or excess Zn(II) conditions. A lot-dependent variation was also observed for Type A and Type E but not for Nacalai: hypersensitive phenotypes of cad1-3, cad1-6, and abcc1/2 under As(III) or Hg(II) treatments were diminished when different batches of the Type A or Type E agar types were used. We also found a significant variation of As and Hg accumulation in the wild-type and cad1-3. Plant As and Hg concentrations were remarkably higher and the difference between the genotypes was more evident when grown with Type A agar plates. We finally analyzed ionomic profiles in the plants exposed to As(III) stress. Agar-type specific ionomic changes in cad1-3 were more observed with the Type A plates than with the Nacalai plates. The presented results overall suggest that suitability of agar reagents for metal(loid)-related phenotyping depends on the experimental design, and an inappropriate selection of agar reagents can mask even very clear phenotypes of the established mutant like cad1-3. We also discuss perspectives on the agar problem in the plant metal study.
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13
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Hématy K, Lim M, Cherk C, Piślewska-Bednarek M, Sanchez-Rodriguez C, Stein M, Fuchs R, Klapprodt C, Lipka V, Molina A, Grill E, Schulze-Lefert P, Bednarek P, Somerville S. Moonlighting Function of Phytochelatin Synthase1 in Extracellular Defense against Fungal Pathogens. PLANT PHYSIOLOGY 2020; 182:1920-1932. [PMID: 31992602 PMCID: PMC7140922 DOI: 10.1104/pp.19.01393] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 01/06/2020] [Indexed: 05/04/2023]
Abstract
Phytochelatin synthase (PCS) is a key component of heavy metal detoxification in plants. PCS catalyzes both the synthesis of the peptide phytochelatin from glutathione and the degradation of glutathione conjugates via peptidase activity. Here, we describe a role for PCS in disease resistance against plant pathogenic fungi. The pen4 mutant, which is allelic to cadmium insensitive1 (cad1/pcs1) mutants, was recovered from a screen for Arabidopsis mutants with reduced resistance to the nonadapted barley fungal pathogen Blumeria graminis f. sp. hordei PCS1, which is found in the cytoplasm of cells of healthy plants, translocates upon pathogen attack and colocalizes with the PEN2 myrosinase on the surface of immobilized mitochondria. pcs1 and pen2 mutant plants exhibit similar metabolic defects in the accumulation of pathogen-inducible indole glucosinolate-derived compounds, suggesting that PEN2 and PCS1 act in the same metabolic pathway. The function of PCS1 in this pathway is independent of phytochelatin synthesis and deglycination of glutathione conjugates, as catalytic-site mutants of PCS1 are still functional in indole glucosinolate metabolism. In uncovering a peptidase-independent function for PCS1, we reveal this enzyme to be a moonlighting protein important for plant responses to both biotic and abiotic stresses.
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Affiliation(s)
- Kian Hématy
- Carnegie Institution for Science, Department of Plant Biology, Stanford, California 94350
- Energy Biosciences Institute, University of California at Berkeley, Berkeley, California 94720
| | - Melisa Lim
- Carnegie Institution for Science, Department of Plant Biology, Stanford, California 94350
- Energy Biosciences Institute, University of California at Berkeley, Berkeley, California 94720
| | - Candice Cherk
- Energy Biosciences Institute, University of California at Berkeley, Berkeley, California 94720
| | - Mariola Piślewska-Bednarek
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, D-50829 Köln, Germany
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, 61-704 Poznań, Poland
| | - Clara Sanchez-Rodriguez
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Campus de Montegancedo-UPM, E-28223-Pozuelo de Alarcón (Madrid), Spain
| | - Monica Stein
- Carnegie Institution for Science, Department of Plant Biology, Stanford, California 94350
| | - Rene Fuchs
- University of Goettingen, Schwann-Schleiden Research Center for Molecular Cell Biology, Albrecht-von-Haller-Institute for Plant Sciences, Department of Plant Cell BiologyD-37077 Goettingen, Germany
| | - Christine Klapprodt
- University of Goettingen, Schwann-Schleiden Research Center for Molecular Cell Biology, Albrecht-von-Haller-Institute for Plant Sciences, Department of Plant Cell BiologyD-37077 Goettingen, Germany
| | - Volker Lipka
- University of Goettingen, Schwann-Schleiden Research Center for Molecular Cell Biology, Albrecht-von-Haller-Institute for Plant Sciences, Department of Plant Cell BiologyD-37077 Goettingen, Germany
| | - Antonio Molina
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Campus de Montegancedo-UPM, E-28223-Pozuelo de Alarcón (Madrid), Spain
- Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, E-28020-Madrid, Spain
| | - Erwin Grill
- Lehrstuhl für Botanik, Technische Universtät München, D-85350 Freising, Germany
| | - Paul Schulze-Lefert
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, D-50829 Köln, Germany
| | - Paweł Bednarek
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, D-50829 Köln, Germany
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, 61-704 Poznań, Poland
| | - Shauna Somerville
- Carnegie Institution for Science, Department of Plant Biology, Stanford, California 94350
- Energy Biosciences Institute, University of California at Berkeley, Berkeley, California 94720
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14
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The Moss Leptodictyum riparium Counteracts Severe Cadmium Stress by Activation of Glutathione Transferase and Phytochelatin Synthase, but Slightly by Phytochelatins. Int J Mol Sci 2020; 21:ijms21051583. [PMID: 32111035 PMCID: PMC7084805 DOI: 10.3390/ijms21051583] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 02/21/2020] [Accepted: 02/24/2020] [Indexed: 02/07/2023] Open
Abstract
In the present work, we investigated the response to Cd in Leptodictyum riparium, a cosmopolitan moss (Bryophyta) that can accumulate higher amounts of metals than other plants, even angiosperms, with absence or slight apparent damage. High-performance liquid chromatography followed by electrospray ionization tandem mass spectrometry of extracts from L. riparium gametophytes, exposed to 0, 36 and 360 µM Cd for 7 days, revealed the presence of γ-glutamylcysteine (γ-EC), reduced glutathione (GSH), and traces of phytochelatins. The increase in Cd concentrations progressively augmented reactive oxygen species levels, with activation of both antioxidant (catalase and superoxide dismutase) and detoxifying (glutathione-S-transferase) enzymes. After Cd treatment, cytosolic and vacuolar localization of thiol peptides was performed by means of the fluorescent dye monochlorobimane and subsequent observation with confocal laser scanning microscopy. The cytosolic fluorescence observed with the highest Cd concentrations was also consistent with the formation of γ-EC-bimane in the cytosol, possibly catalyzed by the peptidase activity of the L. riparium phytochelatin synthase. On the whole, activation of phytochelatin synthase and glutathione-S-transferase, but minimally phytochelatin synthesis, play a role to counteract Cd toxicity in L. riparium, in this manner minimizing the cellular damage caused by the metal. This study strengthens previous investigations on the L. riparium ability to efficiently hinder metal pollution, hinting at a potential use for biomonitoring and phytoremediation purposes.
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15
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Yazdi M, Kolahi M, Mohajel Kazemi E, Goldson Barnaby A. Study of the contamination rate and change in growth features of lettuce (Lactuca sativa Linn.) in response to cadmium and a survey of its phytochelatin synthase gene. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 180:295-308. [PMID: 31100594 DOI: 10.1016/j.ecoenv.2019.04.071] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 04/18/2019] [Accepted: 04/24/2019] [Indexed: 05/09/2023]
Abstract
Crops can become contaminated when grown in soils containing heavy metals. Cadmium is a heavy metal that poses a significant health risk to humans. The purpose of this study was to evaluate the effect of cadmium on lettuce (Lactuca sativa Linn) and the contamination risk of lettuce grown in cadmium environments. The results showed that photosynthesis and growth parameters were significantly affected by cadmium. Lettuce has the ability to absorb large amounts of cadmium from the contaminated environment and so is a cadmium hyperaccumulator plant. The study showed that approximately 35% of the total absorbed cadmium is transmitted to aerial and edible parts of lettuce. This study was undertaken as lettuce has the ability to absorb and accumulate high levels of cadmium. There are however are no reports on the PCS gene and the potential for high cadmium accumulation in lettuce. The bioinformatics study revealed that lettuce has two phytochelatin synthase genes that produce 6 PCSs through splicing leading to the ability of lettuce to store high levels of cadmium. These six sequences although different in length have high similarity. Sequence structure, cellular location, three-dimensional structure, phylogeny and a comparison of their catalytic power were evaluated. The high accumulation of cadmium in lettuce and the presence of several PCSs contribute to the accumulation of cadmium in aerial tissues. The cultivation of lettuce in contaminated environments led us to evaluate suspected farms for the presence of cadmium in produce. Lettuce grown in industrial environments contaminated with cadmium can pose a serious threat to human health.
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Affiliation(s)
- M Yazdi
- Department of Genetics, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran
| | - M Kolahi
- Department of Biology, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran.
| | - E Mohajel Kazemi
- Department of Plant Biology, Faculty of Natural Science, University of Tabriz, Tabriz, Iran
| | - A Goldson Barnaby
- Department of Chemistry, University of the West Indies, Mona, Jamaica
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16
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Park HC, Hwang JE, Jiang Y, Kim YJ, Kim SH, Nguyen XC, Kim CY, Chung WS. Functional characterisation of two phytochelatin synthases in rice (Oryza sativa cv. Milyang 117) that respond to cadmium stress. PLANT BIOLOGY (STUTTGART, GERMANY) 2019; 21:854-861. [PMID: 30929297 PMCID: PMC6766863 DOI: 10.1111/plb.12991] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 03/26/2019] [Indexed: 05/20/2023]
Abstract
Cadmium (Cd) is one of the most toxic heavy metals and a non-essential element to all organisms, including plants; however, the genes involved in Cd resistance in plants remain poorly characterised. To identify Cd resistance genes in rice, we screened a rice cDNA expression library treated with CdCl2 using a yeast (Saccharomyces cerevisiae) mutant ycf1 strain (DTY167) and isolated two rice phytochelatin synthases (OsPCS5 and OsPCS15). The genes were strongly induced by Cd treatment and conferred increased resistance to Cd when expressed in the ycf1 mutant strain. In addition, the Cd concentration was twofold higher in yeast expressing OsPCS5 and OsPCS15 than in vector-transformed yeast, and OsPCS5 and OsPCS15 localised in the cytoplasm. Arabidopsis thaliana plants overexpressing OsPCS5/-15 paradoxically exhibited increased sensitivity to Cd, suggesting that overexpression of OsPCS5/-15 resulted in toxicity due to excess phytochelatin production in A. thaliana. These data indicate that OsPCS5 and OsPCS15 are involved in Cd tolerance, which may be related to the relative abundances of phytochelatins synthesised by these phytochelatin synthases.
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Affiliation(s)
- H. C. Park
- Division of Ecological ConservationBureau of Ecological ResearchNational Institute of EcologySeocheonRepublic of Korea
| | - J. E. Hwang
- Division of Ecological ConservationBureau of Ecological ResearchNational Institute of EcologySeocheonRepublic of Korea
| | - Y. Jiang
- Division of Applied Life Science (BK21 Plus Program)Plant Molecular Biology and Biotechnology Research CenterGyeongsang National UniversityJinjuRepublic of Korea
| | - Y. J. Kim
- Division of Ecological ConservationBureau of Ecological ResearchNational Institute of EcologySeocheonRepublic of Korea
| | - S. H. Kim
- Division of Applied Life Science (BK21 Plus Program)Plant Molecular Biology and Biotechnology Research CenterGyeongsang National UniversityJinjuRepublic of Korea
| | - X. C. Nguyen
- Faculty of BiotechnologyVietnam National University of AgricultureHanoiVietnam
| | - C. Y. Kim
- Biological Resource CenterKorea Research Institute of Bioscience and Biotechnology (KRIBB)JeongeupRepublic of Korea
| | - W. S. Chung
- Division of Applied Life Science (BK21 Plus Program)Plant Molecular Biology and Biotechnology Research CenterGyeongsang National UniversityJinjuRepublic of Korea
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17
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Common Bean ( Phaseolus vulgaris L.) Accumulates Most S-Methylcysteine as Its γ-Glutamyl Dipeptide. PLANTS 2019; 8:plants8050126. [PMID: 31091711 PMCID: PMC6572574 DOI: 10.3390/plants8050126] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 05/01/2019] [Accepted: 05/12/2019] [Indexed: 02/07/2023]
Abstract
The common bean (Phaseolus vulgaris) constitutes an excellent source of vegetable dietary protein. However, there are sub-optimal levels of the essential amino acids, methionine and cysteine. On the other hand, P. vulgaris accumulates large amounts of the γ-glutamyl dipeptide of S-methylcysteine, and lower levels of free S-methylcysteine and S-methylhomoglutathione. Past results suggest two distinct metabolite pools. Free S-methylcysteine levels are high at the beginning of seed development and decline at mid-maturation, while there is a biphasic accumulation of γ-glutamyl-S-methylcysteine, at early cotyledon and maturation stages. A possible model involves the formation of S-methylcysteine by cysteine synthase from O-acetylserine and methanethiol, whereas the majority of γ-glutamyl-S-methylcysteine may arise from S-methylhomoglutathione. Metabolite profiling during development and in genotypes differing in total S-methylcysteine accumulation showed that γ-glutamyl-S-methylcysteine accounts for most of the total S-methylcysteine in mature seed. Profiling of transcripts for candidate biosynthetic genes indicated that BSAS4;1 expression is correlated with both the developmental timing and levels of free S-methylcysteine accumulated, while homoglutathione synthetase (hGS) expression was correlated with the levels of γ-glutamyl-S-methylcysteine. Analysis of S-methylated phytochelatins by liquid chromatography and high resolution tandem mass spectrometry revealed only small amounts of homophytochelatin-2 with a single S-methylcysteine. The mitochondrial localization of phytochelatin synthase 2—predominant in seed, determined by confocal microscopy of a fusion with the yellow fluorescent protein—and its spatial separation from S-methylhomoglutathione may explain the lack of significant accumulation of S-methylated phytochelatins.
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18
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Filiz E, Saracoglu IA, Ozyigit II, Yalcin B. Comparative analyses of phytochelatin synthase (PCS) genes in higher plants. BIOTECHNOL BIOTEC EQ 2019. [DOI: 10.1080/13102818.2018.1559096] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Affiliation(s)
- Ertugrul Filiz
- Department of Crop and Animal Production, Cilimli Vocational School, Duzce University, Duzce, Turkey
| | | | - Ibrahim Ilker Ozyigit
- Department of Biology, Faculty of Science and Arts, Marmara University, Istanbul, Turkey
- Department of Biology, Faculty of Science, Kyrgyz-Turkish Manas University, Bishkek, Kyrgyzstan
| | - Bahattin Yalcin
- Department of Chemistry, Faculty of Science and Arts, Marmara University, Istanbul, Turkey
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19
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Adams E, Miyazaki T, Watanabe S, Ohkama-Ohtsu N, Seo M, Shin R. Glutathione and Its Biosynthetic Intermediates Alleviate Cesium Stress in Arabidopsis. FRONTIERS IN PLANT SCIENCE 2019; 10:1711. [PMID: 32038683 PMCID: PMC6985154 DOI: 10.3389/fpls.2019.01711] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 12/05/2019] [Indexed: 05/07/2023]
Abstract
Phytoremediation is optimized when plants grow vigorously while accumulating the contaminant of interest. Here we show that sulphur supply alleviates aerial chlorosis and growth retardation caused by cesium stress without reducing cesium accumulation in Arabidopsis thaliana. This alleviation was not due to recovery of cesium-induced potassium decrease in plant tissues. Sulphur supply also alleviated sodium stress but not potassium deficiency stress. Cesium-induced root growth inhibition has previously been demonstrated as being mediated through jasmonate biosynthesis and signalling but it was found that sulphur supply did not decrease the levels of jasmonate accumulation or jasmonate-responsive transcripts. Instead, induction of a glutathione synthetase gene GSH2 and reduction of a phytochelatin synthase gene PCS1 as well as increased accumulation of glutathione and cysteine were observed in response to cesium. Exogenous application of glutathione or concomitant treatments of its biosynthetic intermediates indeed alleviated cesium stress. Interestingly, concomitant treatments of glutathione biosynthetic intermediates together with a glutathione biosynthesis inhibitor did not cancel the alleviatory effects against cesium suggesting the existence of a glutathione-independent pathway. Taken together, our findings demonstrate that plants exposed to cesium increase glutathione accumulation to alleviate the deleterious effects of cesium and that exogenous application of sulphur-containing compounds promotes this innate process.
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Affiliation(s)
- Eri Adams
- RIKEN Center for Sustainable Resource Science, Yokohama, Japan
- *Correspondence: Eri Adams, ; Ryoung Shin,
| | - Takae Miyazaki
- RIKEN Center for Sustainable Resource Science, Yokohama, Japan
| | | | - Naoko Ohkama-Ohtsu
- Institute of Agriculture, Tokyo University of Agriculture and Technology (TUAT), Fuchu, Japan
- Institute of Global Innovation Research, Tokyo University of Agriculture and Technology (TUAT), Fuchu, Japan
| | - Mitsunori Seo
- RIKEN Center for Sustainable Resource Science, Yokohama, Japan
| | - Ryoung Shin
- RIKEN Center for Sustainable Resource Science, Yokohama, Japan
- *Correspondence: Eri Adams, ; Ryoung Shin,
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Arabidopsis mutants impaired in glutathione biosynthesis exhibit higher sensitivity towards the glucosinolate hydrolysis product allyl-isothiocyanate. Sci Rep 2018; 8:9809. [PMID: 29955088 PMCID: PMC6023892 DOI: 10.1038/s41598-018-28099-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 06/15/2018] [Indexed: 11/16/2022] Open
Abstract
Upon tissue damage the plant secondary metabolites glucosinolates can generate various hydrolysis products, including isothiocyanates (ITCs). Their role in plant defence against insects and pest and their potential health benefits have been well documented, but our knowledge regarding the endogenous molecular mechanisms of their effect in plants is limited. Here we investigated the effect of allyl-isothiocyanate (AITC) on Arabidopsis thaliana mutants impaired in homeostasis of the low-molecular weight thiol glutathione. We show that glutathione is important for the AITC-induced physiological responses, since mutants deficient in glutathione biosynthesis displayed a lower biomass and higher root growth inhibition than WT seedlings. These mutants were also more susceptible than WT to another ITC, sulforaphane. Sulforaphane was however more potent in inhibiting root growth than AITC. Combining AITC with the glutathione biosynthesis inhibitor L-buthionine-sulfoximine (BSO) led to an even stronger phenotype than observed for the single treatments. Furthermore, transgenic plants expressing the redox-sensitive fluorescent biomarker roGFP2 indicated more oxidative conditions during AITC treatment. Taken together, we provide genetic evidence that glutathione plays an important role in AITC-induced growth inhibition, although further studies need to be conducted to reveal the underlying mechanisms.
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Zhang X, Rui H, Zhang F, Hu Z, Xia Y, Shen Z. Overexpression of a Functional Vicia sativa PCS1 Homolog Increases Cadmium Tolerance and Phytochelatins Synthesis in Arabidopsis. FRONTIERS IN PLANT SCIENCE 2018; 9:107. [PMID: 29467781 PMCID: PMC5808204 DOI: 10.3389/fpls.2018.00107] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 01/19/2018] [Indexed: 05/05/2023]
Abstract
Phytochelatins (PCs) catalyzed by phytochelatin synthases (PCS) are important for the detoxification of metals in plants and other living organisms. In this study, we isolated a PCS gene (VsPCS1) from Vicia sativa and investigated its role in regulating cadmium (Cd) tolerance. Expression of VsPCS1 was induced in roots of V. sativa under Cd stress. Analysis of subcellular localization showed that VsPCS1 was localized in the cytoplasm of mesophyll protoplasts of V. sativa. Overexpression of VsPCS1 (35S::VsPCS1, in wild-type background) in Arabidopsis thaliana could complement the defects of Cd tolerance of AtPCS1-deficent mutant (atpcs1). Compared with atpcs1 mutants, 35S::VsPCS1/atpcs1 (in AtPCS1-deficent mutant background) transgenic plants significantly lowered Cd-fluorescence intensity in mesophyll cytoplasm, accompanied with enhanced Cd-fluorescence intensity in the vacuoles, demonstrating that the increased Cd tolerance may be attributed to the increased PC-based sequestration of Cd into the vacuole. Furthermore, overexpressing VsPCS1 could enhance the Cd tolerance in 35S::VsPCS1, but have no effect on Cd accumulation and distribution, showing the same level of Cd-fluorescence intensity between 35S::VsPCS1 and wild-type (WT) plants. Further analysis indicated this increased tolerance in 35S::VsPCS1 was possibly due to the increased PCs-chelated Cd in cytosol. Taken together, a functional PCS1 homolog from V. sativa was identified, which hold a strong catalyzed property for the synthesis of high-order PCs that retained Cd in the cytosol rather the vacuole. These findings enrich the original model of Cd detoxification mediated by PCS in higher plants.
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Affiliation(s)
- Xingxing Zhang
- College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Haiyun Rui
- College of Pharmacy and Chemistry and Chemical Engineering, Taizhou University, Taizhou, China
| | - Fenqin Zhang
- College of Agriculture and Biotechnology, Hexi University, Zhangye, China
| | - Zhubing Hu
- College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Yan Xia
- College of Life Sciences, Nanjing Agricultural University, Nanjing, China
- *Correspondence: Yan Xia,
| | - Zhenguo Shen
- College of Life Sciences, Nanjing Agricultural University, Nanjing, China
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Yamazaki S, Ueda Y, Mukai A, Ochiai K, Matoh T. Rice phytochelatin synthases OsPCS1 and OsPCS2 make different contributions to cadmium and arsenic tolerance. PLANT DIRECT 2018; 2:e00034. [PMID: 31245682 PMCID: PMC6508543 DOI: 10.1002/pld3.34] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2017] [Revised: 12/05/2017] [Accepted: 12/14/2017] [Indexed: 05/18/2023]
Abstract
Cadmium (Cd) and arsenic (As) pollution in paddy soil and their accumulation in rice (Oryza sativa) pose serious threats to human health. Rice internally detoxifies these toxic metal and metalloid to some extent, resulting in their accumulation within the edible parts. However, the mechanisms of Cd and As detoxification in rice have been poorly elucidated. Plants synthesize thiol-rich metal-chelating peptides, termed phytochelatins (PCs). We characterized rice PC synthase (PCS) and investigated its contribution to Cd and As tolerance in rice. We identified two PCS homolog genes, OsPCS1 and OsPCS2, in the rice genome. The expression of OsPCS1 was upregulated by As(III) stress in the roots but that of OsPCS2 was not significantly affected. The expression level of OsPCS2 was higher than that of OsPCS1 in the shoots and roots. Recombinant OsPCS1 and OsPCS2 proteins differed in their metal activation. OsPCS1 was more strongly activated by As(III) than by Cd; however, OsPCS2 was more strongly activated by Cd than by As(III). Genetically engineered plants having their OsPCS2 expression silenced via RNA interference (OsPCS2 RNAi) contained less PCs and more glutathione (GSH), a substrate of PC synthesis, than wild-type plants, although there was no significant difference in OsPCS1 RNAi plants. OsPCS2 RNAi plants were sensitive to As(III) stress, but Cd tolerance was little affected. On the other hand, treatment with buthionine sulfoximine, an inhibitor of GSH biosynthesis, significantly decreased Cd and As tolerance of rice seedlings. These findings indicate that OsPCS2 is a major isozyme controlling PC synthesis, and that PCs are important for As tolerance in rice. However, PC synthesis may make a smaller contribution to Cd tolerance in rice, and GSH plays crucial roles, not only as a substrate of PC synthesis.
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Affiliation(s)
| | - Yosuke Ueda
- Graduate School of AgricultureKyoto UniversityKyotoJapan
| | - Aya Mukai
- Graduate School of AgricultureKyoto UniversityKyotoJapan
| | - Kumiko Ochiai
- Graduate School of AgricultureKyoto UniversityKyotoJapan
| | - Toru Matoh
- Graduate School of AgricultureKyoto UniversityKyotoJapan
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Zayneb C, Imen RH, Walid K, Grubb CD, Bassem K, Franck V, Hafedh M, Amine E. The phytochelatin synthase gene in date palm (Phoenix dactylifera L.): Phylogeny, evolution and expression. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2017; 140:7-17. [PMID: 28231507 DOI: 10.1016/j.ecoenv.2017.02.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 02/11/2017] [Accepted: 02/13/2017] [Indexed: 06/06/2023]
Abstract
We studied date palm phytochelatin synthase type I (PdPCS1), which catalyzes the cytosolic synthesis of phytochelatins (PCs), a heavy metal binding protein, in plant cells. The gene encoding PdPCS1 (Pdpcs) consists of 8 exons and 7 introns and encodes a protein of 528 amino acids. PCs gene history was studied using Notung phylogeny. During evolution, gene loss from several lineages was predicted including Proteobacteria, Bilateria and Brassicaceae. In addition, eleven gene duplication events appeared toward interior nodes of the reconciled tree and four gene duplication events appeared toward the external nodes. These latter sequences belong to species with a second copy of PCs suggesting that this gene evolved through subfunctionalization. Pdpcs1 gene expression was measured in seedling hypocotyls exposed to Cd, Cu and Cr using quantitative real-time polymerase chain reaction (qPCR). A Pdpcs1 overexpression was evidenced in P. dactylifera seedlings exposed to metals suggesting that 1-the Pdpcs1 gene is functional, 2-there is an implication of the enzyme in metal detoxification mechanisms. Additionally, the structure of PdPCS1 was predicted using its homologue from Nostoc (cyanobacterium, NsPCS) as a template in Discovery studio and PyMol software. These analyses allowed us to identify the phytochelatin synthase type I enzyme in date palm (PdPCS1) via recognition of key consensus amino acids involved in the catalytic mechanism, and to propose a hypothetical binding and catalytic site for an additional substrate binding cavity.
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Affiliation(s)
- Chaâbene Zayneb
- Laboratory of Plant Biotechnology, Faculty of Sciences, University of Sfax, BP 1171, 3000 Sfax, Tunisia; Laboratoire de Génie Civil et géo-Environnement, Université de Lille 1, F-59655 Villeneuve d'Ascq, France
| | - Rekik Hakim Imen
- Laboratory of Plant Biotechnology, Faculty of Sciences, University of Sfax, BP 1171, 3000 Sfax, Tunisia
| | - Kriaa Walid
- Laboratory of Plant Biotechnology, Faculty of Sciences, University of Sfax, BP 1171, 3000 Sfax, Tunisia
| | - C Douglas Grubb
- Biorecycling Operations Research Laboratory, Des Moines, IA, USA
| | - Khemakhem Bassem
- Laboratory of Plant Biotechnology, Faculty of Sciences, University of Sfax, BP 1171, 3000 Sfax, Tunisia
| | - Vandenbulcke Franck
- Laboratoire de Génie Civil et géo-Environnement, Université de Lille 1, F-59655 Villeneuve d'Ascq, France
| | - Mejdoub Hafedh
- Laboratory of Plant Biotechnology, Faculty of Sciences, University of Sfax, BP 1171, 3000 Sfax, Tunisia
| | - Elleuch Amine
- Laboratory of Plant Biotechnology, Faculty of Sciences, University of Sfax, BP 1171, 3000 Sfax, Tunisia.
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Kühnlenz T, Westphal L, Schmidt H, Scheel D, Clemens S. Expression of Caenorhabditis elegans PCS in the AtPCS1-deficient Arabidopsis thaliana cad1-3 mutant separates the metal tolerance and non-host resistance functions of phytochelatin synthases. PLANT, CELL & ENVIRONMENT 2015; 38:2239-47. [PMID: 25764348 DOI: 10.1111/pce.12534] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 02/19/2015] [Accepted: 03/06/2015] [Indexed: 05/22/2023]
Abstract
Phytochelatin synthases (PCS) play key roles in plant metal tolerance. They synthesize small metal-binding peptides, phytochelatins, under conditions of metal excess. Respective mutants are strongly cadmium and arsenic hypersensitive. However, their ubiquitous presence and constitutive expression had long suggested a more general function of PCS besides metal detoxification. Indeed, phytochelatin synthase1 from Arabidopsis thaliana (AtPCS1) was later implicated in non-host resistance. The two different physiological functions may be attributable to the two distinct catalytic activities demonstrated for AtPCS1, that is the dipeptidyl transfer onto an acceptor molecule in phytochelatin synthesis, and the proteolytic deglycylation of glutathione conjugates. In order to test this hypothesis and to possibly separate the two biological roles, we expressed a phylogenetically distant PCS from Caenorhabditis elegans in an AtPCS1 mutant. We confirmed the involvement of AtPCS1 in non-host resistance by showing that plants lacking the functional gene develop a strong cell death phenotype when inoculated with the potato pathogen Phytophthora infestans. Furthermore, we found that the C. elegans gene rescues phytochelatin synthesis and cadmium tolerance, but not the defect in non-host resistance. This strongly suggests that the second enzymatic function of AtPCS1, which remains to be defined in detail, is underlying the plant immunity function.
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Affiliation(s)
- Tanja Kühnlenz
- Department of Plant Physiology, University of Bayreuth, Universitätsstrasse 30, Bayreuth, 95440, Germany
| | - Lore Westphal
- Department of Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry, Weinberg 3, Halle, 06120, Germany
| | - Holger Schmidt
- Department of Plant Physiology, University of Bayreuth, Universitätsstrasse 30, Bayreuth, 95440, Germany
| | - Dierk Scheel
- Department of Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry, Weinberg 3, Halle, 06120, Germany
| | - Stephan Clemens
- Department of Plant Physiology, University of Bayreuth, Universitätsstrasse 30, Bayreuth, 95440, Germany
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Hernández LE, Sobrino-Plata J, Montero-Palmero MB, Carrasco-Gil S, Flores-Cáceres ML, Ortega-Villasante C, Escobar C. Contribution of glutathione to the control of cellular redox homeostasis under toxic metal and metalloid stress. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:2901-11. [PMID: 25750419 DOI: 10.1093/jxb/erv063] [Citation(s) in RCA: 141] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The accumulation of toxic metals and metalloids, such as cadmium (Cd), mercury (Hg), or arsenic (As), as a consequence of various anthropogenic activities, poses a serious threat to the environment and human health. The ability of plants to take up mineral nutrients from the soil can be exploited to develop phytoremediation technologies able to alleviate the negative impact of toxic elements in terrestrial ecosystems. However, we must select plant species or populations capable of tolerating exposure to hazardous elements. The tolerance of plant cells to toxic elements is highly dependent on glutathione (GSH) metabolism. GSH is a biothiol tripeptide that plays a fundamental dual role: first, as an antioxidant to mitigate the redox imbalance caused by toxic metal(loid) accumulation, and second as a precursor of phytochelatins (PCs), ligand peptides that limit the free ion cellular concentration of those pollutants. The sulphur assimilation pathway, synthesis of GSH, and production of PCs are tightly regulated in order to alleviate the phytotoxicity of different hazardous elements, which might induce specific stress signatures. This review provides an update on mechanisms of tolerance that depend on biothiols in plant cells exposed to toxic elements, with a particular emphasis on the Hg-triggered responses, and considering the contribution of hormones to their regulation.
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Affiliation(s)
- Luis E Hernández
- Laboratory of Plant Physiology, Department of Biology, Universidad Autónoma de Madrid, Cantoblanco, ES-28049 Madrid, Spain
| | - Juan Sobrino-Plata
- Laboratory of Plant Physiology, Department of Biology, Universidad Autónoma de Madrid, Cantoblanco, ES-28049 Madrid, Spain Department of Environmental Sciences, Universidad de Castilla-La Mancha, Campus Fábrica de Armas, ES-45070 Toledo, Spain
| | - M Belén Montero-Palmero
- Laboratory of Plant Physiology, Department of Biology, Universidad Autónoma de Madrid, Cantoblanco, ES-28049 Madrid, Spain Department of Environmental Sciences, Universidad de Castilla-La Mancha, Campus Fábrica de Armas, ES-45070 Toledo, Spain
| | - Sandra Carrasco-Gil
- Laboratory of Plant Physiology, Department of Biology, Universidad Autónoma de Madrid, Cantoblanco, ES-28049 Madrid, Spain † Present address: Aula Dei Experimental Research Station-CSIC, Avd. Montañana, ES- 50059 Zaragoza, Spain
| | - M Laura Flores-Cáceres
- Laboratory of Plant Physiology, Department of Biology, Universidad Autónoma de Madrid, Cantoblanco, ES-28049 Madrid, Spain
| | - Cristina Ortega-Villasante
- Laboratory of Plant Physiology, Department of Biology, Universidad Autónoma de Madrid, Cantoblanco, ES-28049 Madrid, Spain
| | - Carolina Escobar
- Department of Environmental Sciences, Universidad de Castilla-La Mancha, Campus Fábrica de Armas, ES-45070 Toledo, Spain
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Phytochelatin synthase is required for tolerating metal toxicity in a basidiomycete yeast and is a conserved factor involved in metal homeostasis in fungi. Fungal Biol Biotechnol 2015; 2. [PMID: 25926993 PMCID: PMC4410428 DOI: 10.1186/s40694-015-0013-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Background Phytochelatin synthase (PCS) is an enzyme that catalyzes the biosynthesis of phytochelatin from glutathione. Phytochelatins protect cells against the toxic effects of non-essential heavy metals, such as cadmium, and hence growth is restricted in the presence of these metals in mutants in PCS-encoding genes. PCS genes from fungi have been characterized in only two species in the Ascomycota, and these genes are considered sparsely distributed in the fungal kingdom. Results A gene encoding a putative PCS was identified in Sporobolomyces sp. strain IAM 13481, a fungus that is a member of the Pucciniomycotina subphylum of the Basidiomycota. The function of this PCS1 gene was assessed by heterologous expression in the Ascomycota yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe, and by mutating the gene in Sporobolomyces. The gene is required for tolerance to toxic concentrations of non-essential cadmium as well as the essential metal copper. Pcs1 homologs in fungi and other eukaryotes have putative targeting sequences for mitochondrial localization: the S. pombe homolog was fused to green fluorescent protein and it co-localized with a mitochondrial dye. Evaluation of the presence or absence of PCS and PCS-like homologs in the genome sequences of fungi indicates that they have a wide distribution, and the absence in most Ascomycota and Basidiomycota (the Dikarya) species can be explained by a small number of gene losses. Conclusions The ecology of the species within the fungi carrying putative PCS genes, the phenotypes of phytochelatin synthase mutants in two major fungal lineages, and the presence of homologs in many non-Dikarya lineages parallel what is seen in the plant and animal kingdoms. That is, PCS is a protein present early during the evolution of the fungi and whose role is not solely dedicated to combating toxic concentrations of non-essential metals. Electronic supplementary material The online version of this article (doi:10.1186/s40694-015-0013-3) contains supplementary material, which is available to authorized users.
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Zechmann B. Compartment-specific importance of glutathione during abiotic and biotic stress. FRONTIERS IN PLANT SCIENCE 2014; 5:566. [PMID: 25368627 PMCID: PMC4202713 DOI: 10.3389/fpls.2014.00566] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 10/01/2014] [Indexed: 05/19/2023]
Abstract
The tripeptide thiol glutathione (γ-L-glutamyl-L-cysteinyl-glycine) is the most important sulfur containing antioxidant in plants and essential for plant defense against abiotic and biotic stress conditions. It is involved in the detoxification of reactive oxygen species (ROS), redox signaling, the modulation of defense gene expression, and the regulation of enzymatic activities. Even though changes in glutathione contents are well documented in plants and its roles in plant defense are well established, still too little is known about its compartment-specific importance during abiotic and biotic stress conditions. Due to technical advances in the visualization of glutathione and the redox state through microscopical methods some progress was made in the last few years in studying the importance of subcellular glutathione contents during stress conditions in plants. This review summarizes the data available on compartment-specific importance of glutathione in the protection against abiotic and biotic stress conditions such as high light stress, exposure to cadmium, drought, and pathogen attack (Pseudomonas, Botrytis, tobacco mosaic virus). The data will be discussed in connection with the subcellular accumulation of ROS during these conditions and glutathione synthesis which are both highly compartment specific (e.g., glutathione synthesis takes place in chloroplasts and the cytosol). Thus this review will reveal the compartment-specific importance of glutathione during abiotic and biotic stress conditions.
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Affiliation(s)
- Bernd Zechmann
- Center for Microscopy and Imaging, Baylor University, Waco, TX, USA
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Sobrino-Plata J, Carrasco-Gil S, Abadía J, Escobar C, Álvarez-Fernández A, Hernández LE. The role of glutathione in mercury tolerance resembles its function under cadmium stress in Arabidopsis. Metallomics 2014; 6:356-66. [PMID: 24452078 DOI: 10.1039/c3mt00329a] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Recent research efforts have highlighted the importance of glutathione (GSH) as a key antioxidant metabolite for metal tolerance in plants. Little is known about the mechanisms involved in stress due to mercury (Hg), one of the most hazardous metals to the environment and human health. To understand the implication of GSH metabolism for Hg tolerance, we used two γ-glutamylcysteine synthetase (γECS) Arabidopsis thaliana allele mutants (rax1-1 and cad2-1) and a phytochelatin synthase (PCS) mutant (cad1-3). The leaves of these mutants and of wild type (Col-0) were infiltrated with a solution containing Cd or Hg (0, 3 and 30 μM) and incubated for 24 and 48 h. The formation of phytochelatins (PCs) in the leaf extracts was followed by two different HPLC-based methods and occurred in Col-0, cad2-1 and rax1-1 plants exposed to Cd, whereas in the Hg treatments, PCs accumulated mainly in Col-0 and rax1-1, where Hg-PC complexes were also detected. ASA and GSH/GSSG levels increased under moderate metal stress conditions, accompanied by increased GSH reductase (GR) activity and expression. However, higher metal doses led to a decrease in the analysed parameters, and stronger toxic effects appeared with 30 μM Hg. The GSH concentration was significantly higher in rax1-1 (70% of Col-0) than in cad2-1 (40% of Col-0). The leaves of rax1-1 were less sensitive than cad2-1, in accordance with the greater expression of γECS in rax1-1. Our results underline the existence of a minimal GSH concentration threshold needed to minimise the toxic effects exerted by Hg.
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Affiliation(s)
- Juan Sobrino-Plata
- Laboratory of Plant Physiology, Department of Biology, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.
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Kühnlenz T, Schmidt H, Uraguchi S, Clemens S. Arabidopsis thaliana phytochelatin synthase 2 is constitutively active in vivo and can rescue the growth defect of the PCS1-deficient cad1-3 mutant on Cd-contaminated soil. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:4241-53. [PMID: 24821959 PMCID: PMC4112630 DOI: 10.1093/jxb/eru195] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Phytochelatins play a key role in the detoxification of metals in plants and many other eukaryotes. Their formation is catalysed by phytochelatin synthases (PCS) in the presence of metal excess. It appears to be common among higher plants to possess two PCS genes, even though in Arabidopsis thaliana only AtPCS1 has been demonstrated to confer metal tolerance. Employing a highly sensitive quantification method based on ultraperformance electrospray ionization quadrupole time-of-flight mass spectrometry, we detected AtPCS2-dependent phytochelatin formation. Overexpression of AtPCS2 resulted in constitutive phytochelatin accumulation, i.e. in the absence of metal excess, both in planta and in a heterologous system. This indicates distinct enzymatic differences between AtPCS1 and AtPCS2. Furthermore, AtPCS2 was able to partially rescue the Cd hypersensitivity of the AtPCS1-deficient cad1-3 mutant in a liquid seedling assay, and, more importantly, when plants were grown on soil spiked with Cd to a level that is close to what can be found in agricultural soils. No rescue was found in vertical-plate assays, the most commonly used method to assess metal tolerance. Constitutive AtPCS2-dependent phytochelatin synthesis suggests a physiological role of AtPCS2 other than metal detoxification. The differences observed between wild-type plants and cad1-3 on Cd soil demonstrated: (i) the essentiality of phytochelatin synthesis for tolerating levels of Cd contamination that can naturally be encountered by plants outside of metal-rich habitats, and (ii) a contribution to Cd accumulation under these conditions.
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Affiliation(s)
- Tanja Kühnlenz
- Department of Plant Physiology, University of Bayreuth, Universitätsstrasse 30, 95447 Bayreuth, Germany
| | - Holger Schmidt
- Department of Plant Physiology, University of Bayreuth, Universitätsstrasse 30, 95447 Bayreuth, Germany
| | - Shimpei Uraguchi
- Department of Plant Physiology, University of Bayreuth, Universitätsstrasse 30, 95447 Bayreuth, Germany
| | - Stephan Clemens
- Department of Plant Physiology, University of Bayreuth, Universitätsstrasse 30, 95447 Bayreuth, Germany
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Gläser K, Kanawati B, Kubo T, Schmitt-Kopplin P, Grill E. Exploring the Arabidopsis sulfur metabolome. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 77:31-45. [PMID: 24147819 DOI: 10.1111/tpj.12359] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Revised: 10/09/2013] [Accepted: 10/16/2013] [Indexed: 05/18/2023]
Abstract
Sulfur plays a crucial role in protein structure and function, redox status and plant biotic stress responses. However, our understanding of sulfur metabolism is limited to identified pathways. In this study, we used a high-resolution Fourier transform mass spectrometric approach in combination with stable isotope labeling to describe the sulfur metabolome of Arabidopsis thaliana. Databases contain roughly 300 sulfur compounds assigned to Arabidopsis. In comparative analyses, we showed that the overlap of the expected sulfur metabolome and the mass spectrometric data was surprisingly low, and we were able to assign only 37 of the 300 predicted compounds. By contrast, we identified approximately 140 sulfur metabolites that have not been assigned to the databases to date. We used our method to characterize the γ-glutamyl transferase mutant ggt4-1, which is involved in the vacuolar breakdown of glutathione conjugates in detoxification reactions. Although xenobiotic substrates are well known, only a few endogenous substrates have been described. Among the specifically altered sulfur-containing masses in the ggt4-1 mutant, we characterized one endogenous glutathione conjugate and a number of further candidates for endogenous substrates. The small percentage of predicted compounds and the high proportion of unassigned sulfur compounds identified in this study emphasize the need to re-evaluate our understanding of the sulfur metabolome.
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Affiliation(s)
- Katharina Gläser
- Lehrstuhl für Botanik, Technische Universität München, Emil-Ramann Straße 4, D-85354, Freising, Germany
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Krajewski MP, Kanawati B, Fekete A, Kowalski N, Schmitt-Kopplin P, Grill E. Analysis of Arabidopsis glutathione-transferases in yeast. PHYTOCHEMISTRY 2013; 91:198-207. [PMID: 22633844 DOI: 10.1016/j.phytochem.2012.04.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Revised: 02/24/2012] [Accepted: 04/24/2012] [Indexed: 06/01/2023]
Abstract
The genome of Arabidopsis thaliana encodes 54 functional glutathione transferases (GSTs), classified in seven clades. Although plant GSTs have been implicated in the detoxification of xenobiotics, such as herbicides, extensive redundancy within this large gene family impedes a functional analysis in planta. In this study, a GST-deficient yeast strain was established as a system for analyzing plant GSTs that allows screening for GST substrates and identifying substrate preferences within the plant GST family. To this end, five yeast genes encoding GSTs and GST-related proteins were simultaneously disrupted. The resulting yeast quintuple mutant showed a strongly reduced conjugation of the GST substrates 1-chloro-2,4-dinitrobenzene (CDNB) and 4-chloro-7-nitro-2,1,3-benzoxadiazole (NBD-Cl). Consistently, the quintuple mutant was hypersensitive to CDNB, and this phenotype was complemented by the inducible expression of Arabidopsis GSTs. The conjugating activity of the plant GSTs was assessed by in vitro enzymatic assays and via analysis of exposed yeast cells. The formation of glutathione adducts with dinitrobenzene was unequivocally verified by stable isotope labeling and subsequent accurate ultrahigh-resolution mass spectrometry (ICR-FTMS). Analysis of Arabidopsis GSTs encompassing six clades and 42 members demonstrated functional expression in yeast by using CDNB and NBD-Cl as model substrates. Subsequently, the established yeast system was explored for its potential to screen the Arabidopsis GST family for conjugation of the fungicide anilazine. Thirty Arabidopsis GSTs were identified that conferred increased levels of glutathionylated anilazine. Efficient anilazine conjugation was observed in the presence of the phi, tau, and theta clade GSTs including AtGSTF2, AtGSTF4, AtGSTF6, AtGSTF8, AtGSTF10, and AtGSTT2, none of which had previously been known to contribute to fungicide detoxification. ICR-FTMS analysis of yeast extracts allowed the simultaneous detection and semiquantification of anilazine conjugates as well as catabolites.
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32
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Amaral CDB, Nóbrega JA, Nogueira ARA. Sample preparation for arsenic speciation in terrestrial plants--a review. Talanta 2013; 115:291-9. [PMID: 24054594 DOI: 10.1016/j.talanta.2013.04.072] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 04/24/2013] [Accepted: 04/25/2013] [Indexed: 12/31/2022]
Abstract
Arsenic is an element widely present in nature. Additionally, it may be found as different species in several matrices and therefore it is one of the target elements in chemical speciation. Although the number of studies in terrestrial plants is low, compared to matrices such as fish or urine, this number is raising due to the fact that this type of matrix are closely related to the human food chain. In speciation analysis, sample preparation is a critical step and several extraction procedures present drawbacks. In this review, papers dealing with extraction procedures, analytical methods, and studies of species conservation in plants cultivated in terrestrial environment are critically discussed. Analytical procedures based on extractions using water or diluted acid solutions associated with HPLC-ICP-MS are good alternatives, owing to their versatility and sensitivity, even though less expensive strategies are shown as feasible choices.
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Affiliation(s)
- Clarice D B Amaral
- Group of Applied Instrumental Analysis, Department of Chemistry, Federal University of São Carlos, PO Box 676, 13560-970 São Carlos, SP, Brazil; Embrapa Southeast Livestock, PO Box 339, 13560-970 São Carlos, SP, Brazil
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Molins H, Michelet L, Lanquar V, Agorio A, Giraudat J, Roach T, Krieger-Liszkay A, Thomine S. Mutants impaired in vacuolar metal mobilization identify chloroplasts as a target for cadmium hypersensitivity in Arabidopsis thaliana. PLANT, CELL & ENVIRONMENT 2013; 36:804-17. [PMID: 22998565 DOI: 10.1111/pce.12016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Cadmium (Cd) is highly toxic to plants causing growth reduction and chlorosis. It binds thiols and competes with essential transition metals. It affects major biochemical processes such as photosynthesis and the redox balance, but the connection between cadmium effects at the biochemical level and its deleterious effect on growth has seldom been established. In this study, two Cd hypersensitive mutants, cad1-3 impaired in phytochelatin synthase (PCS1), and nramp3nramp4 impaired in release of vacuolar metal stores, have been compared. The analysis combines genetics with measurements of photosynthetic and antioxidant functions. Loss of AtNRAMP3 and AtNRAMP4 function or of PCS1 function leads to comparable Cd sensitivity. Root Cd hypersensitivities conferred by cad1-3 and nramp3nramp4 are cumulative. The two mutants contrast in their tolerance to oxidative stress. In nramp3nramp4, the photosynthetic apparatus is severely affected by Cd, whereas it is much less affected in cad1-3. In agreement with chloroplast being a prime target for Cd toxicity in nramp3nramp4, the Cd hypersensitivity of this mutant is alleviated in the dark. The Cd hypersensitivity of nramp3nramp4 mutant highlights the critical role of vacuolar metal stores to supply essential metals to plastids and maintain photosynthetic function under Cd and oxidative stresses.
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Affiliation(s)
- Hélène Molins
- Institut des Sciences du Végétal, CNRS, Gif-sur-Yvette 91198, France
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Meyer Y, Belin C, Delorme-Hinoux V, Reichheld JP, Riondet C. Thioredoxin and glutaredoxin systems in plants: molecular mechanisms, crosstalks, and functional significance. Antioxid Redox Signal 2012; 17:1124-60. [PMID: 22531002 DOI: 10.1089/ars.2011.4327] [Citation(s) in RCA: 216] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Thioredoxins (Trx) and glutaredoxins (Grx) constitute families of thiol oxidoreductases. Our knowledge of Trx and Grx in plants has dramatically increased during the last decade. The release of the Arabidopsis genome sequence revealed an unexpectedly high number of Trx and Grx genes. The availability of several genomes of vascular and nonvascular plants allowed the establishment of a clear classification of the genes and the chronology of their appearance during plant evolution. Proteomic approaches have been developed that identified the putative Trx and Grx target proteins which are implicated in all aspects of plant growth, including basal metabolism, iron/sulfur cluster formation, development, adaptation to the environment, and stress responses. Analyses of the biochemical characteristics of specific Trx and Grx point to a strong specificity toward some target enzymes, particularly within plastidial Trx and Grx. In apparent contradiction with this specificity, genetic approaches show an absence of phenotype for most available Trx and Grx mutants, suggesting that redundancies also exist between Trx and Grx members. Despite this, the isolation of mutants inactivated in multiple genes and several genetic screens allowed the demonstration of the involvement of Trx and Grx in pathogen response, phytohormone pathways, and at several control points of plant development. Cytosolic Trxs are reduced by NADPH-thioredoxin reductase (NTR), while the reduction of Grx depends on reduced glutathione (GSH). Interestingly, recent development integrating biochemical analysis, proteomic data, and genetics have revealed an extensive crosstalk between the cytosolic NTR/Trx and GSH/Grx systems. This crosstalk, which occurs at multiple levels, reveals the high plasticity of the redox systems in plants.
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Affiliation(s)
- Yves Meyer
- Laboratoire Génome et Développement des Plantes, Université de Perpignan, Perpignan, France
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Bednarek P. Sulfur-containing secondary metabolites from Arabidopsis thaliana and other Brassicaceae with function in plant immunity. Chembiochem 2012; 13:1846-59. [PMID: 22807086 DOI: 10.1002/cbic.201200086] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2012] [Indexed: 11/10/2022]
Abstract
Biosynthesis of antimicrobial secondary metabolites in response to microbial infection is one of the features of the plant immune system. Particular classes of plant secondary metabolites involved in plant defence are often produced only by species belonging to certain phylogenetic clades. Brassicaceae plants have evolved the ability to synthesise a wide range of sulfur-containing secondary metabolites, including glucosinolates and indole-type phytoalexins. A subset of these compounds is produced by the model plant Arabidopsis thaliana. Genetic tools available for this species enabled verification of immune functions of glucosinolates and camalexin (A. thaliana phytoalexin), as well as characterisation of their respective biosynthetic pathways. Current knowledge of the biosynthesis of Brassicaceae sulfur-containing metabolites suggests that the key event in the evolution of these compounds is the acquisition of biochemical mechanisms originating from detoxification pathways into secondary metabolite biosynthesis. Moreover, it is likely that glucosinolates and Brassicaceae phytoalexins, traditionally considered as separate groups of compounds, have a common evolutionary origin and are interconnected on the biosynthetic level. This suggests that the diversity of Brassicaceae sulfur-containing phytochemicals reflect phylogenetic clade-specific branches of an ancient biosynthetic pathway.
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Affiliation(s)
- Paweł Bednarek
- Laboratory of Proteomics and Metabolomics, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, Poznań, Poland.
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Abstract
Of the mechanisms known to protect vascular plants and some algae, fungi and invertebrates from the toxic effects of non-essential heavy metals such as As, Cd or Hg, one of the most sophisticated is the enzyme-catalyzed synthesis of phytochelatins (PCs). PCs, (γ-Glu-Cys)(n) Gly polymers, which serve as high-affinity, thiol-rich cellular chelators and contribute to the detoxification of heavy metal ions, are derived from glutathione (GSH; γ-Glu-Cys-Gly) and related thiols in a reaction catalyzed by phytochelatin synthases (PC synthases, EC 2.3.2.15). Using the enzyme from Arabidopsis thaliana (AtPCS1) as a model, the reasoning and experiments behind the conclusion that PC synthases are novel papain-like Cys protease superfamily members are presented. The status of S-substituted GSH derivatives as generic PC synthase substrates and the sufficiency of the N-terminal domain of the enzyme from eukaryotic and its half-size equivalents from prokaryotic sources, for net PC synthesis and deglycylation of GSH and its derivatives, respectively, are emphasized. The question of the common need or needs met by PC synthases and their homologs is discussed. Of the schemes proposed to account for the combined protease and peptide polymerase capabilities of the eukaryotic enzymes vs the limited protease capabilities of the prokaryotic enzymes, two that will be considered are the storage and homeostasis of essential heavy metals in eukaryotes and the metabolism of S-substituted GSH derivatives in both eukaryotes and prokaryotes.
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Affiliation(s)
- Philip A Rea
- Carolyn Hoff Lynch Biology Laboratory, Plant Science Institute, Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA.
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Noctor G, Mhamdi A, Chaouch S, Han Y, Neukermans J, Marquez-Garcia B, Queval G, Foyer CH. Glutathione in plants: an integrated overview. PLANT, CELL & ENVIRONMENT 2012; 35:454-84. [PMID: 21777251 DOI: 10.1111/j.1365-3040.2011.02400.x] [Citation(s) in RCA: 791] [Impact Index Per Article: 65.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
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.
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Affiliation(s)
- Graham Noctor
- Institut de Biologie des Plantes, UMR CNRS 8618, Université de Paris sud 11, Orsay cedex, France.
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Guo J, Xu W, Ma M. The assembly of metals chelation by thiols and vacuolar compartmentalization conferred increased tolerance to and accumulation of cadmium and arsenic in transgenic Arabidopsis thaliana. JOURNAL OF HAZARDOUS MATERIALS 2012; 199-200:309-13. [PMID: 22119299 DOI: 10.1016/j.jhazmat.2011.11.008] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 11/02/2011] [Accepted: 11/03/2011] [Indexed: 05/18/2023]
Abstract
Transgenic Arabidopsis thaliana were developed to increase tolerance for and accumulation of heavy metals and metalloids by simultaneous overexpression of AsPCS1 and YCF1 (derived from garlic and baker's yeast) based on the fact that chelation of metals and vacuolar compartmentalization are the main strategies for heavy metals/metalloids detoxification and tolerance in plants. Dual-gene transgenic lines had the longest roots and the highest accumulation of Cd and As than single-gene transgenic lines and wildtype. When grown on cadmium or arsenic (arsenite/arsenate), Dual-gene transgenic lines accumulated over 2-10 folds cadmium/arsenite and 2-3 folds arsenate than wild type or plants expressing AsPCS1 or YCF1 alone. Such stacking modified genes involved in chelation of toxic metals and vacuolar compartmentalization represents a highly promising new tool for use in phytoremediation efforts.
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Affiliation(s)
- Jiangbo Guo
- Key Laboratory of Plant Resources, Institute of Botany, The Chinese Academy of Sciences, Beijing 100093, PR China
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Biochemical and Functional Responses of Arabidopsis thaliana Exposed to Cadmium, Copper and Zinc. THE PLANT FAMILY BRASSICACEAE 2012. [DOI: 10.1007/978-94-007-3913-0_9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/06/2022]
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Bräutigam A, Schaumlöffel D, Preud'homme H, Thondorf I, Wesenberg D. Physiological characterization of cadmium-exposed Chlamydomonas reinhardtii. PLANT, CELL & ENVIRONMENT 2011; 34:2071-2082. [PMID: 21819413 DOI: 10.1111/j.1365-3040.2011.02404.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Chlamydomonas reinhardtii is a common model organism for investigation of metal stress. This green alga produces phytochelatins in the presence of metal ions. The influence of cadmium is of main interest, because it is a strong activator of phytochelatin synthase. Cell wall bound and intracellular cadmium content was determined after exposition to 70 µm CdCl(2), showing the main portion of the metal outside the cell. Nevertheless, imported cadmium was sufficient to cause significant changes in thiolpeptide metabolism and its transcriptional regulation. Modern analytical approaches enable new insights into phytochelatin (PC) distribution. A new rapid and precise UPLC-MS method allowed high-throughput PC quantification in algal samples after 1, 4, 24 and 48 h cadmium stress. Initially, canonic PCs were synthesized in C. reinhardtii during cadmium exposition, but afterwards CysPCs became the major thiolpeptides. Thus, after 48 h the concentration of the PC-isoforms CysPC(2-3) and CysGSH attained between 105 and 199 nmol g(-1) fresh weight (FW), whereas the PC(2-3) concentrations were only 15 nmol g(-1) FW. The relative quantification of γ-glutamyl transpeptidase (γ-GT) mRNA suggests the generation of CysPCs by glutamate cleavage from canonic PCs by γ-GT. Furthermore, a homology model of C. reinhardtii phytochelatin synthase was constructed to verify the use of crystal structures from Anabaena sp. phytochelatin synthase (PCS) for docking studies with canonical PCs and CysPCs. From the difference in energy scores, we hypothesize that CysPC may prevent the synthesis of canonical PCs by blocking the binding pocket. Finally, possible physiological reasons for the high abundance of CysPC compared with their canonic precursors are discussed.
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Affiliation(s)
- Anja Bräutigam
- Martin-Luther-Universität Halle-Wittenberg, Institut für Biochemie und Biotechnologie, Abteilung Ökologische und Pflanzen-Biochemie, 06120 Halle (Saale), Germany
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41
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Koffler BE, Maier R, Zechmann B. Subcellular distribution of glutathione precursors in Arabidopsis thaliana. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2011; 53:930-41. [PMID: 22050910 PMCID: PMC3588602 DOI: 10.1111/j.1744-7909.2011.01085.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Glutathione is an important antioxidant and has many important functions in plant development, growth and defense. Glutathione synthesis and degradation is highly compartment-specific and relies on the subcellular availability of its precursors, cysteine, glutamate, glycine and γ-glutamylcysteine especially in plastids and the cytosol which are considered as the main centers for glutathione synthesis. The availability of glutathione precursors within these cell compartments is therefore of great importance for successful plant development and defense. The aim of this study was to investigate the compartment-specific importance of glutathione precursors in Arabidopsis thaliana. The subcellular distribution was compared between wild type plants (Col-0), plants with impaired glutathione synthesis (glutathione deficient pad2-1 mutant, wild type plants treated with buthionine sulfoximine), and one complemented line (OE3) with restored glutathione synthesis. Immunocytohistochemistry revealed that the inhibition of glutathione synthesis induced the accumulation of the glutathione precursors cysteine, glutamate and glycine in most cell compartments including plastids and the cytosol. A strong decrease could be observed in γ-glutamylcysteine (γ-EC) contents in these cell compartments. These experiments demonstrated that the inhibition of γ-glutamylcysteine synthetase (GSH1) - the first enzyme of glutathione synthesis - causes a reduction of γ-EC levels and an accumulation of all other glutathione precursors within the cells.
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Brunetti P, Zanella L, Proia A, De Paolis A, Falasca G, Altamura MM, Sanità di Toppi L, Costantino P, Cardarelli M. Cadmium tolerance and phytochelatin content of Arabidopsis seedlings over-expressing the phytochelatin synthase gene AtPCS1. JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:5509-19. [PMID: 21841172 PMCID: PMC3223047 DOI: 10.1093/jxb/err228] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Revised: 06/27/2011] [Accepted: 06/28/2011] [Indexed: 05/18/2023]
Abstract
Previous studies demonstrated that expression of the Arabidopsis phytochelatin (PC) biosynthetic gene AtPCS1 in Nicotiana tabacum plants increases the Cd tolerance in the presence of exogenous glutathione (GSH). In this paper, the Cd tolerance of Arabidopsis plants over-expressing AtPCS1 (AtPCSox lines) has been analysed and the differences between Arabidopsis and tobacco are shown. Based on the analysis of seedling fresh weight, primary root length, and alterations in root anatomy, evidence is provided that, at relatively low Cd concentrations, the Cd tolerance of AtPCSox lines is lower than the wild type, while AtPCS1 over-expressing tobacco is more tolerant to Cd than the wild type. At higher Cd concentrations, Arabidopsis AtPCSox seedlings are more tolerant to Cd than the wild type, while tobacco AtPCS1 seedlings are as sensitive as the wild type. Exogenous GSH, in contrast to what was observed in tobacco, did not increase the Cd tolerance of AtPCSox lines. The PC content in wild-type Arabidopsis at low Cd concentrations is more than three times higher than in tobacco and substantial differences were also found in the PC chain lengths. These data indicate that the differences in Cd tolerance and in its dependence on exogenous GSH between Arabidopsis and tobacco are due to species-specific differences in the endogenous content of PCs and GSH and may be in the relative abundance of PCs of different length.
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Affiliation(s)
- Patrizia Brunetti
- Dipartimento di Biologia e Biotecnologie (formerly Dipartimento di Genetica e Biologia Molecolare), Sapienza Università di Roma, Italy
| | - Letizia Zanella
- Dipartimento di Biologia Ambientale (formerly Dipartimento di Biologia Vegetale), Sapienza Università di Roma, Italy
| | - Alessandra Proia
- IBPM-CNR Dipartimento di Biologia e Biotecnologie (formerly Dipartimento di Genetica e Biologia Molecolare), Sapienza Università di Roma, Italy
| | | | - Giuseppina Falasca
- Dipartimento di Biologia Ambientale (formerly Dipartimento di Biologia Vegetale), Sapienza Università di Roma, Italy
| | - Maria Maddalena Altamura
- Dipartimento di Biologia Ambientale (formerly Dipartimento di Biologia Vegetale), Sapienza Università di Roma, Italy
| | | | - Paolo Costantino
- Dipartimento di Biologia e Biotecnologie (formerly Dipartimento di Genetica e Biologia Molecolare), Sapienza Università di Roma, Italy
| | - Maura Cardarelli
- IBPM-CNR Dipartimento di Biologia e Biotecnologie (formerly Dipartimento di Genetica e Biologia Molecolare), Sapienza Università di Roma, Italy
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43
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Meyer CL, Peisker D, Courbot M, Craciun AR, Cazalé AC, Desgain D, Schat H, Clemens S, Verbruggen N. Isolation and characterization of Arabidopsis halleri and Thlaspi caerulescens phytochelatin synthases. PLANTA 2011; 234:83-95. [PMID: 21369921 DOI: 10.1007/s00425-011-1378-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Accepted: 02/07/2011] [Indexed: 05/13/2023]
Abstract
The synthesis of phytochelatins (PC) represents a major metal and metalloid detoxification mechanism in various species. PC most likely play a role in the distribution and accumulation of Cd and possibly other metals. However, to date, no studies have investigated the phytochelatin synthase (PCS) genes and their expression in the Cd-hyperaccumulating species. We used functional screens in two yeast species to identify genes expressed by two Cd hyperaccumulators (Arabidopsis halleri and Thlaspi caerulescens) and involved in cellular Cd tolerance. As a result of these screens, PCS genes were identified for both species. PCS1 was in each case the dominating cDNA isolated. The deduced sequences of AhPCS1 and TcPCS1 are very similar to AtPCS1 and their identity is particularly high in the proposed catalytic N-terminal domain. We also identified in A. halleri and T. caerulescens orthologues of AtPCS2 that encode functional PCS. As compared to A. halleri and A. thaliana, T. caerulescens showed the lowest PCS expression. Furthermore, concentrations of PC in Cd-treated roots were the highest in A. thaliana, intermediate in A. halleri and the lowest in T. caerulescens. This mirrors the known capacity of these species to translocate Cd to the shoot, with T. caerulescens being the best translocator. Very low or undetectable concentrations of PC were measured in A. halleri and T. caerulescens shoots, contrary to A. thaliana. These results suggest that extremely efficient alternative Cd sequestration pathways in leaves of Cd hyperaccumulators prevent activation of PC synthase by Cd²⁺ ions.
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Affiliation(s)
- Claire-Lise Meyer
- Faculté des Sciences, Laboratoire de Physiologie & de Génétique moléculaire des Plantes, Université Libre de Bruxelles, Campus Plaine CP242, 1050 Brussels, Belgium
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44
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Noctor G, Queval G, Mhamdi A, Chaouch S, Foyer CH. Glutathione. THE ARABIDOPSIS BOOK 2011; 9:e0142. [PMID: 22303267 PMCID: PMC3267239 DOI: 10.1199/tab.0142] [Citation(s) in RCA: 133] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Glutathione is a simple sulfur compound composed of three amino acids and the major non-protein thiol in many organisms, including plants. The functions of glutathione are manifold but notably include redox-homeostatic buffering. Glutathione status is modulated by oxidants as well as by nutritional and other factors, and can influence protein structure and activity through changes in thiol-disulfide balance. For these reasons, glutathione is a transducer that integrates environmental information into the cellular network. While the mechanistic details of this function remain to be fully elucidated, accumulating evidence points to important roles for glutathione and glutathione-dependent proteins in phytohormone signaling and in defense against biotic stress. Work in Arabidopsis is beginning to identify the processes that govern glutathione status and that link it to signaling pathways. As well as providing an overview of the components that regulate glutathione homeostasis (synthesis, degradation, transport, and redox turnover), the present discussion considers the roles of this metabolite in physiological processes such as light signaling, cell death, and defense against microbial pathogen and herbivores.
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Affiliation(s)
- Graham Noctor
- Institut de Biologie des Plantes, UMR CNRS 8618, Université de Paris sud 11, 91405 Orsay cedex, France
| | - Guillaume Queval
- Institut de Biologie des Plantes, UMR CNRS 8618, Université de Paris sud 11, 91405 Orsay cedex, France
- Present address: Department of Plant Systems Biology, Flanders Institute for Biotechnology and Department of Plant Biotechnologyand Genetics, Gent University, 9052 Gent, Belgium
| | - Amna Mhamdi
- Institut de Biologie des Plantes, UMR CNRS 8618, Université de Paris sud 11, 91405 Orsay cedex, France
| | - Sejir Chaouch
- Institut de Biologie des Plantes, UMR CNRS 8618, Université de Paris sud 11, 91405 Orsay cedex, France
| | - Christine H. Foyer
- Centre for Plant Sciences, Faculty of Biology, University of Leeds, Leeds, LS2 9JT, UK
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45
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Noctor G, Queval G, Mhamdi A, Chaouch S, Foyer CH. Glutathione. THE ARABIDOPSIS BOOK 2011. [PMID: 22303267 DOI: 10.1199/tab0142] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Glutathione is a simple sulfur compound composed of three amino acids and the major non-protein thiol in many organisms, including plants. The functions of glutathione are manifold but notably include redox-homeostatic buffering. Glutathione status is modulated by oxidants as well as by nutritional and other factors, and can influence protein structure and activity through changes in thiol-disulfide balance. For these reasons, glutathione is a transducer that integrates environmental information into the cellular network. While the mechanistic details of this function remain to be fully elucidated, accumulating evidence points to important roles for glutathione and glutathione-dependent proteins in phytohormone signaling and in defense against biotic stress. Work in Arabidopsis is beginning to identify the processes that govern glutathione status and that link it to signaling pathways. As well as providing an overview of the components that regulate glutathione homeostasis (synthesis, degradation, transport, and redox turnover), the present discussion considers the roles of this metabolite in physiological processes such as light signaling, cell death, and defense against microbial pathogen and herbivores.
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