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Maruta T, Tanaka Y, Yamamoto K, Ishida T, Hamada A, Ishikawa T. Evolutionary insights into strategy shifts for the safe and effective accumulation of ascorbate in plants. J Exp Bot 2024; 75:2664-2681. [PMID: 38452239 DOI: 10.1093/jxb/erae062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 03/06/2024] [Indexed: 03/09/2024]
Abstract
Plants accumulate high concentrations of ascorbate, commonly in their leaves, as a redox buffer. While ascorbate levels have increased during plant evolution, the mechanisms behind this phenomenon are unclear. Moreover, has the increase in ascorbate concentration been achieved without imposing any detrimental effects on the plants? In this review, we focus on potential transitions in two regulatory mechanisms related to ascorbate biosynthesis and the availability of cellular dehydroascorbate (DHA) during plant evolution. The first transition might be that the trigger for the transcriptional induction of VTC2, which encodes the rate-limiting enzyme in ascorbate biosynthesis, has shifted from oxidative stress (in green algae) to light/photosynthesis (in land plants), probably enabling the continuous accumulation of ascorbate under illumination. This could serve as a preventive system against the unpredictable occurrence of oxidative stress. The second transition might be that DHA-degrading enzymes, which protect cells from the highly reactive DHA in green algae and mosses, have been lost in ferns or flowering plants. Instead, flowering plants may have increased glutathione concentrations to reinforce the DHA reduction capacity, possibly allowing ascorbate accumulation and avoiding the toxicity of DHA. These potential transitions may have contributed to strategies for plants' safe and effective accumulation of ascorbate.
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Affiliation(s)
- Takanori Maruta
- Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan
- Bioresource and Life Sciences, The United Graduate School of Agricultural Sciences, Tottori University, 4-101 Koyama-Minami, Tottori, Tottori 680-8553, Japan
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan
| | - Yasuhiro Tanaka
- Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan
- Bioresource and Life Sciences, The United Graduate School of Agricultural Sciences, Tottori University, 4-101 Koyama-Minami, Tottori, Tottori 680-8553, Japan
| | - Kojiro Yamamoto
- Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan
| | - Tetsuya Ishida
- Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan
| | - Akane Hamada
- Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan
| | - Takahiro Ishikawa
- Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan
- Bioresource and Life Sciences, The United Graduate School of Agricultural Sciences, Tottori University, 4-101 Koyama-Minami, Tottori, Tottori 680-8553, Japan
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan
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Tanaka M, Takahashi R, Hamada A, Terai Y, Ogawa T, Sawa Y, Ishikawa T, Maruta T. Distribution and Functions of Monodehydroascorbate Reductases in Plants: Comprehensive Reverse Genetic Analysis of Arabidopsis thaliana Enzymes. Antioxidants (Basel) 2021; 10:antiox10111726. [PMID: 34829597 PMCID: PMC8615211 DOI: 10.3390/antiox10111726] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 10/22/2021] [Accepted: 10/27/2021] [Indexed: 11/16/2022] Open
Abstract
Monodehydroascorbate reductase (MDAR) is an enzyme involved in ascorbate recycling. Arabidopsis thaliana has five MDAR genes that encode two cytosolic, one cytosolic/peroxisomal, one peroxisomal membrane-attached, and one chloroplastic/mitochondrial isoform. In contrast, tomato plants possess only three enzymes, lacking the cytosol-specific enzymes. Thus, the number and distribution of MDAR isoforms differ according to plant species. Moreover, the physiological significance of MDARs remains poorly understood. In this study, we classify plant MDARs into three classes: class I, chloroplastic/mitochondrial enzymes; class II, peroxisomal membrane-attached enzymes; and class III, cytosolic/peroxisomal enzymes. The cytosol-specific isoforms form a subclass of class III and are conserved only in Brassicaceae plants. With some exceptions, all land plants and a charophyte algae, Klebsormidium flaccidum, contain all three classes. Using reverse genetic analysis of Arabidopsis thaliana mutants lacking one or more isoforms, we provide new insight into the roles of MDARs; for example, (1) the lack of two isoforms in a specific combination results in lethality, and (2) the role of MDARs in ascorbate redox regulation in leaves can be largely compensated by other systems. Based on these findings, we discuss the distribution and function of MDAR isoforms in land plants and their cooperation with other recycling systems.
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Affiliation(s)
- Mio Tanaka
- Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Shimane, Japan; (M.T.); (A.H.); (T.O.); (T.I.)
- Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Shimane, Japan; (R.T.); (Y.T.); (Y.S.)
| | - Ryuki Takahashi
- Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Shimane, Japan; (R.T.); (Y.T.); (Y.S.)
| | - Akane Hamada
- Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Shimane, Japan; (M.T.); (A.H.); (T.O.); (T.I.)
- Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Shimane, Japan; (R.T.); (Y.T.); (Y.S.)
| | - Yusuke Terai
- Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Shimane, Japan; (R.T.); (Y.T.); (Y.S.)
| | - Takahisa Ogawa
- Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Shimane, Japan; (M.T.); (A.H.); (T.O.); (T.I.)
- Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Shimane, Japan; (R.T.); (Y.T.); (Y.S.)
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Shimane, Japan
| | - Yoshihiro Sawa
- Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Shimane, Japan; (R.T.); (Y.T.); (Y.S.)
| | - Takahiro Ishikawa
- Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Shimane, Japan; (M.T.); (A.H.); (T.O.); (T.I.)
- Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Shimane, Japan; (R.T.); (Y.T.); (Y.S.)
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Shimane, Japan
| | - Takanori Maruta
- Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Shimane, Japan; (M.T.); (A.H.); (T.O.); (T.I.)
- Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Shimane, Japan; (R.T.); (Y.T.); (Y.S.)
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Shimane, Japan
- Correspondence: ; Tel.: +81-882-32-6585
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Zhou F, Zheng B, Wang F, Cao A, Xie S, Chen X, Schick JA, Jin X, Li H. Genome-Wide Analysis of MDHAR Gene Family in Four Cotton Species Provides Insights into Fiber Development via Regulating AsA Redox Homeostasis. Plants (Basel) 2021; 10:plants10020227. [PMID: 33503886 PMCID: PMC7912408 DOI: 10.3390/plants10020227] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 01/17/2021] [Accepted: 01/20/2021] [Indexed: 11/16/2022]
Abstract
Monodehydroasorbate reductase (MDHAR) (EC1.6.5.4), a key enzyme in ascorbate-glutathione recycling, plays important roles in cell growth, plant development and physiological response to environmental stress via control of ascorbic acid (AsA)-mediated reduction/oxidation (redox) regulation. Until now, information regarding MDHAR function and regulatory mechanism in Gossypium have been limited. Herein, a genome-wide identification and comprehensive bioinformatic analysis of 36 MDHAR family genes in four Gossypium species, Gossypium arboreum, G. raimondii, G. hirsutum, and G. barbadense, were performed, indicating their close evolutionary relationship. Expression analysis of GhMDHARs in different cotton tissues and under abiotic stress and phytohormone treatment revealed diverse expression features. Fiber-specific expression analysis showed that GhMDHAR1A/D, 3A/D and 4A/D were preferentially expressed in fiber fast elongating stages to reach peak values in 15-DPA fibers, with corresponding coincident observances of MDHAR enzyme activity, AsA content and ascorbic acid/dehydroascorbic acid (AsA/DHA) ratio. Meanwhile, there was a close positive correlation between the increase of AsA content and AsA/DHA ratio catalyzed by MDHAR and fiber elongation development in different fiber-length cotton cultivars, suggesting the potential important function of MDHAR for fiber growth. Following H2O2 stimulation, GhMDHAR demonstrated immediate responses at the levels of mRNA, enzyme, the product of AsA and corresponding AsA/DHA value, and antioxidative activity. These results for the first time provide a comprehensive systemic analysis of the MDHAR gene family in plants and the four cotton species and demonstrate the contribution of MDHAR to fiber elongation development by controlling AsA-recycling-mediated cellular redox homeostasis.
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Affiliation(s)
- Fangfang Zhou
- Key Laboratory of Xinjiang Phytomedicine Resource and Utilization of Ministry of Education, College of Life Sciences, Shihezi University, Shihezi 832003, China; (F.Z.); (B.Z.); (F.W.); (A.C.); (S.X.); (X.C.)
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, College of Life Sciences, Hainan Normal University, Haikou 571158, China
| | - Bowen Zheng
- Key Laboratory of Xinjiang Phytomedicine Resource and Utilization of Ministry of Education, College of Life Sciences, Shihezi University, Shihezi 832003, China; (F.Z.); (B.Z.); (F.W.); (A.C.); (S.X.); (X.C.)
| | - Fei Wang
- Key Laboratory of Xinjiang Phytomedicine Resource and Utilization of Ministry of Education, College of Life Sciences, Shihezi University, Shihezi 832003, China; (F.Z.); (B.Z.); (F.W.); (A.C.); (S.X.); (X.C.)
| | - Aiping Cao
- Key Laboratory of Xinjiang Phytomedicine Resource and Utilization of Ministry of Education, College of Life Sciences, Shihezi University, Shihezi 832003, China; (F.Z.); (B.Z.); (F.W.); (A.C.); (S.X.); (X.C.)
| | - Shuangquan Xie
- Key Laboratory of Xinjiang Phytomedicine Resource and Utilization of Ministry of Education, College of Life Sciences, Shihezi University, Shihezi 832003, China; (F.Z.); (B.Z.); (F.W.); (A.C.); (S.X.); (X.C.)
| | - Xifeng Chen
- Key Laboratory of Xinjiang Phytomedicine Resource and Utilization of Ministry of Education, College of Life Sciences, Shihezi University, Shihezi 832003, China; (F.Z.); (B.Z.); (F.W.); (A.C.); (S.X.); (X.C.)
| | - Joel A. Schick
- Genetics and Cellular Engineering Group, Institute of Molecular Toxicology and Pharmacology, Helmholtz Zentrum Muenchen, 85764 Neuherberg, Germany;
| | - Xiang Jin
- Key Laboratory of Xinjiang Phytomedicine Resource and Utilization of Ministry of Education, College of Life Sciences, Shihezi University, Shihezi 832003, China; (F.Z.); (B.Z.); (F.W.); (A.C.); (S.X.); (X.C.)
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, College of Life Sciences, Hainan Normal University, Haikou 571158, China
- Correspondence: (X.J.); (H.L.)
| | - Hongbin Li
- Key Laboratory of Xinjiang Phytomedicine Resource and Utilization of Ministry of Education, College of Life Sciences, Shihezi University, Shihezi 832003, China; (F.Z.); (B.Z.); (F.W.); (A.C.); (S.X.); (X.C.)
- Correspondence: (X.J.); (H.L.)
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Abstract
Ascorbic acid (AsA) is an essential compound present in almost all living organisms that has important functions in several aspects of plant growth and development, hormone signaling, as well as stress defense networks. In recent years, the genetic regulation of AsA metabolic pathways has received much attention due to its beneficial role in human diet. Despite the great variability within species, genotypes, tissues and developmental stages, AsA accumulation is considered to be controlled by the fine orchestration of net biosynthesis, recycling, degradation/oxidation, and/or intercellular and intracellular transport. To date, several structural genes from the AsA metabolic pathways and transcription factors are considered to significantly affect AsA in plant tissues, either at the level of activity, transcription or translation via feedback inhibition. Yet, all the emerging studies support the notion that the steps proceeding through GDP-L-galactose phosphorylase and to a lesser extent through GDP-D-mannose-3,5-epimerase are control points in governing AsA pool size in several species. In this mini review, we discuss the current consensus of the genetic regulation of AsA biosynthesis and recycling, with a focus on horticultural crops. The aspects of AsA degradation and transport are not discussed herein. Novel insights of how this multifaceted trait is regulated are critical to prioritize candidate genes for follow-up studies toward improving the nutritional value of fruits and vegetables.
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Affiliation(s)
- Ifigeneia Mellidou
- Group of Biotechnology of Pharmaceutical Plants, Laboratory of Pharmacognosy, Department of Pharmaceutical Sciences, Aristotle University of ThessalonikiThessaloniki, Greece.,Laboratory of Agricultural Chemistry, Department of Crop Science, School of Agriculture, Aristotle University of ThessalonikiThessaloniki, Greece
| | - Angelos K Kanellis
- Group of Biotechnology of Pharmaceutical Plants, Laboratory of Pharmacognosy, Department of Pharmaceutical Sciences, Aristotle University of ThessalonikiThessaloniki, Greece
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Truffault V, Gest N, Garchery C, Florian A, Fernie AR, Gautier H, Stevens RG. Reduction of MDHAR activity in cherry tomato suppresses growth and yield and MDHAR activity is correlated with sugar levels under high light. Plant Cell Environ 2016; 39:1279-92. [PMID: 26510400 DOI: 10.1111/pce.12663] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 10/01/2015] [Accepted: 10/18/2015] [Indexed: 05/08/2023]
Abstract
Ascorbate is oxidized into the radical monodehydroascorbate (MDHA) through ascorbate oxidase or peroxidase activity or non-enzymatically by reactive oxygen species. Regeneration of ascorbate from MDHA is ensured by the enzyme MDHA reductase (MDHAR). Previous work has shown that growth processes and yield can be altered by modifying the activity of enzymes that recycle ascorbate; therefore, we have studied similar processes in cherry tomato (Solanum lycopersium L.) under- or overexpressing MDHAR. Physiological and metabolic characterization of these lines was carried out under different light conditions or by manipulating the source-sink ratio. Independently of the light regime, slower early growth of all organs was observed in MDHAR silenced lines, decreasing final fruit yield. Photosynthesis was altered as was the accumulation of hexoses and sucrose in a light-dependent manner in plantlets. Sucrose accumulation was also repressed in young fruits and final yield of MDHAR silenced lines showed a stronger decrease under carbon limitation, and the phenotype was partially restored by reducing fruit load. Ascorbate and MDHA appear to be involved in control of growth and sugar metabolism in cherry tomato and the associated enzymes could be potential targets for yield improvement.
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Affiliation(s)
- Vincent Truffault
- INRA, UR-1052, Génétique et Amélioration des Fruits et Légumes, CS60094, 84143, Montfavet, France
- INRA, UR-1115, Plantes et Systèmes de Culture Horticoles, CS40509, 84914, Avignon Cedex 9, France
| | - Noé Gest
- INRA, UR-1052, Génétique et Amélioration des Fruits et Légumes, CS60094, 84143, Montfavet, France
| | - Cécile Garchery
- INRA, UR-1052, Génétique et Amélioration des Fruits et Légumes, CS60094, 84143, Montfavet, France
| | - Alexandra Florian
- Max-Planck-Institute of Molecular Plant Physiology, Am Muehlenberf 1, 14476, Potsdam-Golm, Germany
| | - Alisdair R Fernie
- Max-Planck-Institute of Molecular Plant Physiology, Am Muehlenberf 1, 14476, Potsdam-Golm, Germany
| | - Hélène Gautier
- INRA, UR-1115, Plantes et Systèmes de Culture Horticoles, CS40509, 84914, Avignon Cedex 9, France
| | - Rebecca G Stevens
- INRA, UR-1052, Génétique et Amélioration des Fruits et Légumes, CS60094, 84143, Montfavet, France
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Lallement PA, Roret T, Tsan P, Gualberto JM, Girardet JM, Didierjean C, Rouhier N, Hecker A. Insights into ascorbate regeneration in plants: investigating the redox and structural properties of dehydroascorbate reductases from Populus trichocarpa. Biochem J 2016; 473:717-31. [PMID: 26699905 DOI: 10.1042/bj20151147] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 12/23/2015] [Indexed: 12/20/2022]
Abstract
Dehydroascorbate reductases (DHARs), enzymes belonging to the GST superfamily, catalyse the GSH-dependent reduction of dehydroascorbate into ascorbate in plants. By maintaining a reduced ascorbate pool, they notably participate to H2O2 detoxification catalysed by ascorbate peroxidases (APXs). Despite this central role, the catalytic mechanism used by DHARs is still not well understood and there is no supportive 3D structure. In this context, we have performed a thorough biochemical and structural analysis of the three poplar DHARs and coupled this to the analysis of their transcript expression patterns and subcellular localizations. The transcripts for these genes are mainly detected in reproductive and green organs and the corresponding proteins are expressed in plastids, in the cytosol and in the nucleus, but not in mitochondria and peroxisomes where ascorbate regeneration is obviously necessary. Comparing the kinetic properties and the sensitivity to GSSG-mediated oxidation of DHAR2 and DHAR3A, exhibiting 1 or 3 cysteinyl residues respectively, we observed that the presence of additional cysteines in DHAR3A modifies the regeneration mechanism of the catalytic cysteine by forming different redox states. Finally, from the 3D structure of DHAR3A solved by NMR, we were able to map the residues important for the binding of both substrates (GSH and DHA), showing that DHAR active site is very selective for DHA recognition and providing further insights into the catalytic mechanism and the roles of the additional cysteines found in some DHARs.
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Affiliation(s)
- Pierre-Alexandre Lallement
- Université de Lorraine, UMR 1136 Interactions Arbres/Microorganismes, Faculté des Sciences et Technologies, 54506 Vandœuvre-lès-Nancy, France INRA, UMR 1136 Interactions Arbres/Microorganismes, Centre INRA Nancy Lorraine, 54280 Champenoux, France
| | - Thomas Roret
- Université de Lorraine, UMR 1136 Interactions Arbres/Microorganismes, Faculté des Sciences et Technologies, 54506 Vandœuvre-lès-Nancy, France INRA, UMR 1136 Interactions Arbres/Microorganismes, Centre INRA Nancy Lorraine, 54280 Champenoux, France
| | - Pascale Tsan
- Université de Lorraine, CRM2, UMR 7036, 54506 Vandœuvre-lès-Nancy, France CNRS, CRM2, UMR 7036, 54506 Vandœuvre-lès-Nancy, France
| | - José M Gualberto
- Institut de Biologie Moléculaire des Plantes, CNRS-UPR 2357, 67084 Strasbourg, France
| | - Jean-Michel Girardet
- Université de Lorraine, UMR 1136 Interactions Arbres/Microorganismes, Faculté des Sciences et Technologies, 54506 Vandœuvre-lès-Nancy, France INRA, UMR 1136 Interactions Arbres/Microorganismes, Centre INRA Nancy Lorraine, 54280 Champenoux, France
| | - Claude Didierjean
- Université de Lorraine, CRM2, UMR 7036, 54506 Vandœuvre-lès-Nancy, France CNRS, CRM2, UMR 7036, 54506 Vandœuvre-lès-Nancy, France
| | - Nicolas Rouhier
- Université de Lorraine, UMR 1136 Interactions Arbres/Microorganismes, Faculté des Sciences et Technologies, 54506 Vandœuvre-lès-Nancy, France INRA, UMR 1136 Interactions Arbres/Microorganismes, Centre INRA Nancy Lorraine, 54280 Champenoux, France
| | - Arnaud Hecker
- Université de Lorraine, UMR 1136 Interactions Arbres/Microorganismes, Faculté des Sciences et Technologies, 54506 Vandœuvre-lès-Nancy, France INRA, UMR 1136 Interactions Arbres/Microorganismes, Centre INRA Nancy Lorraine, 54280 Champenoux, France
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Zhang C, Huang J, Li X. Transcriptomic Analysis Reveals the Metabolic Mechanism of L-Ascorbic Acid in Ziziphus jujuba Mill. Front Plant Sci 2016; 7:122. [PMID: 26913041 PMCID: PMC4753306 DOI: 10.3389/fpls.2016.00122] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2015] [Accepted: 01/22/2016] [Indexed: 06/01/2023]
Abstract
Chinese jujube (Ziziphus jujuba Mill.) is the most economically important member of the Rhamnaceae family and contains a high concentration of ascorbic acid (AsA). To explore the metabolic mechanism of AsA accumulation, we investigated the abundance of AsA in the fruit development stages, the leaf and flower of Z. jujuba cv Junzao, and the mature fruit of one type of wild jujube (Z. jujuba var. spinosa Hu, Yanchuan sour jujube). And the expression patterns of genes involved in AsA biosynthesis, degradation, and recycling were analyzed. The result showed that AsA biosynthesis during early fruit development (the enlargement stage) is the main reason for jujube high accumulation. The L-galactose pathway plays a predominant role in the biosynthesis of AsA during jujube fruit development, and the genes GMP1, GME1, GGP, and GaLDH involved in the determination of AsA concentration during fruit development and in different genotypes; the myo-inositol pathway along with the genes GME2 and GMP2 in the L-galactose pathway play a compensatory role in maintaining AsA accumulation during the ripening stage. These findings enhance our understanding of the molecular mechanism in regulating AsA accumulation for jujube.
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Root-Bernstein R, Fewins J, Rhinesmith T, Koch A, Dillon PF. Enzymatic recycling of ascorbic acid from dehydroascorbic acid by glutathione-like peptides in the extracellular loops of aminergic G-protein coupled receptors. J Mol Recognit 2016; 29:296-302. [PMID: 26749062 DOI: 10.1002/jmr.2530] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Revised: 11/09/2015] [Accepted: 11/28/2015] [Indexed: 11/11/2022]
Abstract
The intracellular recycling of ascorbic acid from dehydroascorbic acid by the glutathione-glutathione reductase system has been well-characterized. We propose that extracellular recycling of ascorbic acid is performed in a similar manner by cysteine-rich, glutathione-like regions of the first and second extracellular loops of some aminergic receptors including adrenergic, histaminergic, and dopaminergic receptors. Previous research in our laboratory demonstrated that ascorbic acid binds to these receptors at a site on their first or second extracellular loops, significantly enhancing ligand activity, and apparently recycling hundreds of times their own concentration of ascorbate in an enzymatic fashion. In this study, we have synthesized 25 peptides from the first and second extracellular loops of aminergic and insulin receptors and compared them directly to glutathione for their ability to prevent the oxidation of ascorbate and to regenerate ascorbate from dehydroascorbic acid. Peptide sequences that mimic glutathione in containing a cysteine and a glutamic acid-like amino acid also mimic glutathione activity in effects and in kinetics. Some (but not all) peptide sequences that contain one or more methionines instead of cysteine can significantly retard the oxidation of ascorbic acid but do not recycle it from dehydroascorbate into ascorbate. Peptides lacking both cysteines and methionines uniformly failed to alter significantly ascorbate or dehydroascorbate oxidation or reduction. We believe that this is the first proof that receptors may carry out both ligand binding and enzymatic activity extracellularly. Our results suggest the existence of a previously unknown extracellular system for recycling ascorbate. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
| | - Jenna Fewins
- Department of Physiology, Michigan State University, East Lansing, MI, 48824, USA
| | - Tyler Rhinesmith
- Department of Physiology, Michigan State University, East Lansing, MI, 48824, USA
| | - Ariana Koch
- Department of Physiology, Michigan State University, East Lansing, MI, 48824, USA
| | - Patrick F Dillon
- Department of Physiology, Michigan State University, East Lansing, MI, 48824, USA
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9
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Mellidou I, Keulemans J, Kanellis AK, Davey MW. Regulation of fruit ascorbic acid concentrations during ripening in high and low vitamin C tomato cultivars. BMC Plant Biol 2012; 12:239. [PMID: 23245200 PMCID: PMC3548725 DOI: 10.1186/1471-2229-12-239] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Accepted: 12/12/2012] [Indexed: 05/20/2023]
Abstract
BACKGROUND To gain insight into the regulation of fruit ascorbic acid (AsA) pool in tomatoes, a combination of metabolite analyses, non-labelled and radiolabelled substrate feeding experiments, enzyme activity measurements and gene expression studies were carried out in fruits of the 'low-' and 'high-AsA' tomato cultivars 'Ailsa Craig' and 'Santorini' respectively. RESULTS The two cultivars exhibited different profiles of total AsA (totAsA, AsA + dehydroascorbate) and AsA accumulation during ripening, but both displayed a characteristic peak in concentrations at the breaker stage. Substrate feeding experiments demonstrated that the L-galactose pathway is the main AsA biosynthetic route in tomato fruits, but that substrates from alternative pathways can increase the AsA pool at specific developmental stages. In addition, we show that young fruits display a higher AsA biosynthetic capacity than mature ones, but this does not lead to higher AsA concentrations due to either enhanced rates of AsA breakdown ('Ailsa Craig') or decreased rates of AsA recycling ('Santorini'), depending on the cultivar. In the later stages of ripening, differences in fruit totAsA-AsA concentrations of the two cultivars can be explained by differences in the rate of AsA recycling activities. Analysis of the expression of AsA metabolic genes showed that only the expression of one orthologue of GDP-L-galactose phosphorylase (SlGGP1), and of two monodehydroascorbate reductases (SlMDHAR1 and SlMDHAR3) correlated with the changes in fruit totAsA-AsA concentrations during fruit ripening in 'Ailsa Craig', and that only the expression of SlGGP1 was linked to the high AsA concentrations found in red ripe 'Santorini' fruits. CONCLUSIONS Results indicate that 'Ailsa Craig' and 'Santorini' use complementary mechanisms to maintain the fruit AsA pool. In the low-AsA cultivar ('Ailsa Craig'), alternative routes of AsA biosynthesis may supplement biosynthesis via L-galactose, while in the high-AsA cultivar ('Santorini'), enhanced AsA recycling activities appear to be responsible for AsA accumulation in the later stages of ripening. Gene expression studies indicate that expression of SlGGP1 and two orthologues of SlMDHAR are closely correlated with totAsA-AsA concentrations during ripening and are potentially good candidates for marker development for breeding and selection.
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Affiliation(s)
- Ifigeneia Mellidou
- Laboratory for Fruit Breeding and Biotechnology, Department of Biosystems, Faculty of Bioscience Engineering, Katholieke Universiteit Leuven, B-3001, Heverlee, Belgium
| | - Johan Keulemans
- Laboratory for Fruit Breeding and Biotechnology, Department of Biosystems, Faculty of Bioscience Engineering, Katholieke Universiteit Leuven, B-3001, Heverlee, Belgium
| | - Angelos K Kanellis
- Group of Biotechnology of Pharmaceutical Plants. Laboratory of Pharmacognosy, Department of Pharmaceutical Sciences, Aristotle University of Thessaloniki, 541 24, Thessaloniki, Greece
| | - Mark W Davey
- Laboratory for Fruit Breeding and Biotechnology, Department of Biosystems, Faculty of Bioscience Engineering, Katholieke Universiteit Leuven, B-3001, Heverlee, Belgium
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Abstract
Ascorbate (vitamin C) is a vital antioxidant molecule in the brain. However, it also has a number of other important functions, participating as a cofactor in several enzyme reactions, including catecholamine synthesis, collagen production, and regulation of HIF-1 alpha. Ascorbate is transported into the brain and neurons via the sodium-dependent vitamin C transporter 2 (SVCT2), which causes accumulation of ascorbate within cells against a concentration gradient. Dehydroascorbic acid, the oxidized form of ascorbate, is transported via glucose transporters of the GLUT family. Once in cells, it is rapidly reduced to ascorbate. The highest concentrations of ascorbate in the body are found in the brain and in neuroendocrine tissues such as adrenal, although the brain is the most difficult organ to deplete of ascorbate. Combined with regional asymmetry in ascorbate distribution within different brain areas, these facts suggest an important role for ascorbate in the brain. Ascorbate is proposed as a neuromodulator of glutamatergic, dopaminergic, cholinergic, and GABAergic transmission and related behaviors. Neurodegenerative diseases typically involve high levels of oxidative stress and thus ascorbate has been posited to have potential therapeutic roles against ischemic stroke, Alzheimer's disease, Parkinson's disease, and Huntington's disease.
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Affiliation(s)
| | - James M. May
- To whom correspondence should be addressed: Dr. James May, 7465 Medical Research Building IV, Vanderbilt University School of Medicine, Nashville, TN 37232-0475. Tel. (615) 936-1653; Fax: (615) 936-1667. E-mail:
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