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Moreira E, Ferreira J, Coimbra S, Melo P. The significance of the two cytosolic glutamine synthetase enzymes, GLN1;3 and GLN1;5, in the context of seed development and germination in Arabidopsis thaliana. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2024; 210:108631. [PMID: 38657550 DOI: 10.1016/j.plaphy.2024.108631] [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: 11/30/2023] [Revised: 02/21/2024] [Accepted: 04/14/2024] [Indexed: 04/26/2024]
Abstract
Glutamine synthetase (GS), an initial enzyme in nitrogen (N) plant metabolism, exists as a group of isoenzymes found in both cytosolic (GS1) and plastids (GS2) and has gathered significant attention for enhancing N use efficiency and crop yield. This work focuses on the A. thaliana GLN1;3 and GLN1;5 genes, the two predicted most expressed genes in seeds, among the five isogenes encoding GS1 in this species. The expression patterns were studied using transgenic marker line plants and qPCR during seed development and germination. The observed patterns highlight distinct functions for the two genes and confirm GLN1;5 as the most highly expressed GS1 gene in seeds. The GLN1;5, expression, oriented towards hypocotyl and cotyledons, suggests a role in protein turnover during germination, while the radicle-oriented expression of GLN1;3 supports a function in early external N uptake. While the single mutants exhibited a normal phenotype, except for a decrease in seed parameters, the double gln1;3/gln1;5 mutant displayed a germination delay, substantial impairment in growth, nitrogen metabolism, and number and quality of the seeds, as well as a diminishing in flowering. Although seed and pollen-specific, GLN1;5 expression is upregulated in the meristems of the gln1;3 mutants, filling the lack of GLN1;3 and ensuring the normal functioning of the gln1;3 mutants. These findings validate earlier in silico data on the expression patterns of GLN1;3 and GL1;5 genes in seeds, explore their different functions, and underscore their essential role in plant growth, seed production, germination, and early stages of plant development.
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Affiliation(s)
- Emanuel Moreira
- Department of Biology, Faculty of Sciences of the University of Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal; INOV4Agro - GreenUPorto - Research Centre on Sustainable Agri-Food Production, Department of Biology, Faculty of Sciences of the University of Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal.
| | - João Ferreira
- Department of Biology, Faculty of Sciences of the University of Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal.
| | - Sílvia Coimbra
- Department of Biology, Faculty of Sciences of the University of Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal; LAQV/REQUIMTE, Department of Biology, Faculty of Sciences of the University of Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal.
| | - Paula Melo
- Department of Biology, Faculty of Sciences of the University of Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal; INOV4Agro - GreenUPorto - Research Centre on Sustainable Agri-Food Production, Department of Biology, Faculty of Sciences of the University of Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal.
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Moreira E, Coimbra S, Melo P. Glutamine synthetase: an unlikely case of functional redundancy in Arabidopsis thaliana. PLANT BIOLOGY (STUTTGART, GERMANY) 2022; 24:713-720. [PMID: 35246892 DOI: 10.1111/plb.13408] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 01/25/2022] [Indexed: 06/14/2023]
Abstract
Glutamine synthetase (GS, EC 6.3.1.2) is an essential enzyme in plant metabolism, catalysing the assimilation of inorganic nitrogen into the amino acid glutamine. GS is a key enzyme in plant growth and has received special attention due to its recognized roles in plant nitrogen use efficiency and crop productivity. It occurs in plants as a collection of isoenzymes, located in the cytosol (GS1) and plastids (GS2), consistent with the multiplicity of roles played in plant metabolism. It is considered that the different isoenzymes, involved in a wide variety of physiological processes throughout the plant life cycle, perform non-redundant and non-overlapping roles. In fact, specific and non-redundant roles of GS isoenzymes in nitrogen metabolism were observed in species like Oryza sativa and Zea mays. However, in A. thaliana the GS isoenzymes, five cytosolic and one plastidic, are suggested to have functional redundancy and an isoenzyme compensation mechanism, specific to this species, was described. This review integrates analyses on the likely roles of the distinct cytosol- and plastid-located GS isoenzymes in A. thaliana, highlighting the redundancy of the GS gene family specifically occurring in this model plant.
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Affiliation(s)
- E Moreira
- Department of Biology, Faculty of Sciences of the University of Porto, Porto, Portugal
- GreenUPorto - Research Centre on Sustainable Agrifood Production & Department of Biology, Faculty of Sciences of the University of Porto, Porto, Portugal
| | - S Coimbra
- Department of Biology, Faculty of Sciences of the University of Porto, Porto, Portugal
- LAQV/REQUIMTE, Department of Biology, Faculty of Sciences of the University of Porto, Porto, Portugal
| | - P Melo
- Department of Biology, Faculty of Sciences of the University of Porto, Porto, Portugal
- GreenUPorto - Research Centre on Sustainable Agrifood Production & Department of Biology, Faculty of Sciences of the University of Porto, Porto, Portugal
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Dmitrović S, Dragićević M, Savić J, Milutinović M, Živković S, Maksimović V, Matekalo D, Perišić M, Mišić D. Antagonistic Interaction between Phosphinothricin and Nepeta rtanjensis Essential Oil Affected Ammonium Metabolism and Antioxidant Defense of Arabidopsis Grown In Vitro. PLANTS 2021; 10:plants10010142. [PMID: 33445496 PMCID: PMC7828019 DOI: 10.3390/plants10010142] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 01/08/2021] [Accepted: 01/09/2021] [Indexed: 11/17/2022]
Abstract
Phosphinothricin (PPT) is one of the most widely used herbicides. PTT targets glutamine synthetase (GS) activity in plants, and its phytotoxicity is ascribed to ammonium accumulation and reactive oxygen species bursts, which drives rapid lipid peroxidation of cell membranes. In agricultural fields, PPT is extensively sprayed on plant foliage; however, a portion of the herbicide reaches the soil. According to the present study, PPT absorbed via roots can be phytotoxic to Arabidopsis, inducing more adverse effects in roots than in shoots. Alterations in plant physiology caused by 10 days exposure to herbicide via roots are reflected through growth suppression, reduced chlorophyll content, perturbations in the sugar and organic acid metabolism, modifications in the activities and abundances of GS, catalase, peroxidase, and superoxide dismutase. Antagonistic interaction of Nepeta rtanjensis essential oil (NrEO) and PPT, emphasizes the existence of complex control mechanisms at the transcriptional and posttranslational level, which result in the mitigation of PPT-induced ammonium toxicity and in providing more efficient antioxidant defense of plants. Simultaneous application of the two agents in the field cannot be recommended; however, NrEO might be considered as the PPT post-treatment for reducing harmful effects of herbicide residues in the soil on non-target plants.
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Affiliation(s)
- Slavica Dmitrović
- Institute for Biological Research ‘‘Siniša Stanković”—National Institute of Republic of Serbia, University of Belgrade, Bulevar despota Stefana 142, 11060 Belgrade, Serbia; (M.D.); (J.S.); (M.M.); (S.Ž.); (D.M.)
- Correspondence: (S.D.); (D.M.); Tel.: +381112078385 (D.M.)
| | - Milan Dragićević
- Institute for Biological Research ‘‘Siniša Stanković”—National Institute of Republic of Serbia, University of Belgrade, Bulevar despota Stefana 142, 11060 Belgrade, Serbia; (M.D.); (J.S.); (M.M.); (S.Ž.); (D.M.)
| | - Jelena Savić
- Institute for Biological Research ‘‘Siniša Stanković”—National Institute of Republic of Serbia, University of Belgrade, Bulevar despota Stefana 142, 11060 Belgrade, Serbia; (M.D.); (J.S.); (M.M.); (S.Ž.); (D.M.)
| | - Milica Milutinović
- Institute for Biological Research ‘‘Siniša Stanković”—National Institute of Republic of Serbia, University of Belgrade, Bulevar despota Stefana 142, 11060 Belgrade, Serbia; (M.D.); (J.S.); (M.M.); (S.Ž.); (D.M.)
| | - Suzana Živković
- Institute for Biological Research ‘‘Siniša Stanković”—National Institute of Republic of Serbia, University of Belgrade, Bulevar despota Stefana 142, 11060 Belgrade, Serbia; (M.D.); (J.S.); (M.M.); (S.Ž.); (D.M.)
| | - Vuk Maksimović
- Institute for Multidisciplinary Research, University of Belgrade, Kneza Višeslava 1, 11030 Belgrade, Serbia;
| | - Dragana Matekalo
- Institute for Biological Research ‘‘Siniša Stanković”—National Institute of Republic of Serbia, University of Belgrade, Bulevar despota Stefana 142, 11060 Belgrade, Serbia; (M.D.); (J.S.); (M.M.); (S.Ž.); (D.M.)
| | - Mirjana Perišić
- Institute of Physics Belgrade—National Institute of the Republic of Serbia, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia;
| | - Danijela Mišić
- Institute for Biological Research ‘‘Siniša Stanković”—National Institute of Republic of Serbia, University of Belgrade, Bulevar despota Stefana 142, 11060 Belgrade, Serbia; (M.D.); (J.S.); (M.M.); (S.Ž.); (D.M.)
- Correspondence: (S.D.); (D.M.); Tel.: +381112078385 (D.M.)
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Ferreira S, Moreira E, Amorim I, Santos C, Melo P. Arabidopsis thaliana mutants devoid of chloroplast glutamine synthetase (GS2) have non-lethal phenotype under photorespiratory conditions. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2019; 144:365-374. [PMID: 31622939 DOI: 10.1016/j.plaphy.2019.10.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 10/04/2019] [Accepted: 10/08/2019] [Indexed: 06/10/2023]
Abstract
Chloroplast located Glutamine Synthetase (GS2) is believed to play a major role in the reassimilation of ammonium generated by photorespiration, being GS2 knockout mutants unable to grow under photorespiratory conditions (low-CO2 atmosphere) in the species characterized so far (Barley, Lotus). To investigate the importance of GS2 in A. thaliana nitrogen metabolism mutant plants devoid of this GS isoenzyme were characterized. It was shown that GS2 mutants although smaller, slightly chlorotic and with the nitrogen metabolism impaired, were able to grow and complete their life cycle under ordinary air conditions. Surprisingly, GS2 mutants were more tolerant to salt stress than wild-type plants. The lack of GS2 seems to be compensated by higher expression of some GS cytosolic isogenes, namely GLN1;2 and GLN1;3 and by glutamate dehydrogenase, whose activity and expression is enhanced in the GS2 mutant plants and might account for the increased tolerance to salt stress. Under conditions that minimize photorespiration (CO2-enriched atmosphere) plant growth and ammonium assimilation impairment is less evident in the GS2 mutant plants and is accompanied by an adjustment of levels of expression of the cytosolic isogenes, with an increase in the expression of GLN1;3 and a decrease in the expression of the GLN1;1 and GLN1;2. Altogether the results confirm a major role of GS2 in the assimilation of ammonium released during photorespiration, but suggest a redundancy of activity with cytosolic GSs and GDH and further support the involvement of the chloroplastic isoenzyme in primary nitrogen assimilation and plant growth and development in A. thaliana.
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Affiliation(s)
- Sónia Ferreira
- Department of Biology, Faculty of Sciences of the University of Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal.
| | - Emanuel Moreira
- Department of Biology, Faculty of Sciences of the University of Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal.
| | - Isabel Amorim
- Department of Biology, Faculty of Sciences of the University of Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal; GreenUPorto - Research Centre on Sustainable Agri-food Production & Department of Biology, Faculty of Sciences of the University of Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal.
| | - Conceição Santos
- Department of Biology, Faculty of Sciences of the University of Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal; LAQV/REQUIMTE, Department of Biology, Faculty of Sciences of the University of Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal.
| | - Paula Melo
- Department of Biology, Faculty of Sciences of the University of Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal; GreenUPorto - Research Centre on Sustainable Agri-food Production & Department of Biology, Faculty of Sciences of the University of Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal.
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Dmitrović S, Dragićević M, Savić J, Milutinović M, Živković S, Maksimović V, Matekalo D, Mišić D. Nepetalactone-rich essential oil mitigates phosphinothricin-induced ammonium toxicity in Arabidopsis thaliana (L.) Heynh. JOURNAL OF PLANT PHYSIOLOGY 2019; 237:87-94. [PMID: 31034969 DOI: 10.1016/j.jplph.2019.04.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 03/25/2019] [Accepted: 04/10/2019] [Indexed: 06/09/2023]
Abstract
Active ingredient of the commercial herbicide BASTA (B), phosphinothricin, acts as an inhibitor of glutamine synthetase (GS), a key enzyme in ammonium assimilation. The treatment with BASTA leads to an elevation of ammonium levels in plants and further to various physiological alterations, ammonium toxicity and lethality. Results of the present study emphasize the complexity underlying control mechanisms that determine BASTA interaction with essential oil (EO) from Nepeta rtanjensis (NrEO), bioherbicide inducing oxidative stress in target plants. Simultaneous application of NrEO and BASTA, two agents showing differential mode of action, suspends BASTA-induced ammonium toxicity in Arabidopsis thaliana plants. This is achieved through maintaining GS activity, which sustains a sub-toxic and/or sub-lethal ammonium concentration in tissues. As revealed by the present study, regulation of GS activity, as influenced by BASTA and NrEO, occurs at transcriptional, posttranscriptional, and/or posttranslational levels. Two genes encoding cytosolic GS, GLN1;1 and GLN1;3, are highlighted as the main isozymes in Arabidopsis shoots contributing to NrEO-induced overcoming of BASTA-generated ammonium toxicity. The effects of NrEO might be ascribed to its major component nepetalactone, but the contribution of minor EO components should not be neglected. Although of fundamental significance, the results of the present study suggest possible low efficiency of BASTA in plantations of medicinal/aromatic plants such as Nepeta species. Furthermore, these results highlight the possibility of using NrEO as a bioherbicide in BASTA-treated crop fields to mitigate the effect of BASTA residues in contaminated soils.
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Affiliation(s)
- Slavica Dmitrović
- Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060 Belgrade, Serbia
| | - Milan Dragićević
- Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060 Belgrade, Serbia
| | - Jelena Savić
- Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060 Belgrade, Serbia
| | - Milica Milutinović
- Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060 Belgrade, Serbia
| | - Suzana Živković
- Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060 Belgrade, Serbia
| | - Vuk Maksimović
- Institute for Multidisciplinary Research, University of Belgrade, Kneza Višeslava 1, 11030 Belgrade, Serbia
| | - Dragana Matekalo
- Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060 Belgrade, Serbia
| | - Danijela Mišić
- Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060 Belgrade, Serbia.
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Moison M, Marmagne A, Dinant S, Soulay F, Azzopardi M, Lothier J, Citerne S, Morin H, Legay N, Chardon F, Avice JC, Reisdorf-Cren M, Masclaux-Daubresse C. Three cytosolic glutamine synthetase isoforms localized in different-order veins act together for N remobilization and seed filling in Arabidopsis. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:4379-4393. [PMID: 29873769 PMCID: PMC6093384 DOI: 10.1093/jxb/ery217] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 05/30/2018] [Indexed: 05/22/2023]
Abstract
Glutamine synthetase (GS) is central for ammonium assimilation and consists of cytosolic (GS1) and chloroplastic (GS2) isoenzymes. During plant ageing, GS2 protein decreases due to chloroplast degradation, and GS1 activity increases to support glutamine biosynthesis and N remobilization from senescing leaves. The role of the different Arabidopsis GS1 isoforms in nitrogen remobilization was examined using 15N tracing experiments. Only the gln1;1-gln1;2-gln1;3 triple-mutation affecting the three GLN1;1, GLN1;2, and GLN1;3 genes significantly reduced N remobilization, total seed yield, individual seed weight, harvest index, and vegetative biomass. The triple-mutant accumulated a large amount of ammonium that could not be assimilated by GS1. Alternative ammonium assimilation through asparagine biosynthesis was increased and was related to higher ASN2 asparagine synthetase transcript levels. The GS2 transcript, protein, and activity levels were also increased to compensate for the lack of GS1-related glutamine biosynthesis. Localization of the different GLN1 genes showed that they were all expressed in the phloem companion cells but in veins of different order. Our results demonstrate that glutamine biosynthesis for N-remobilization occurs in veins of all orders (major and minor) in leaves, it is mainly catalysed by the three major GS1 isoforms (GLN1;1, GLN1;2, and GLN1;3), and it is alternatively supported by AS2 in the veins and GS2 in the mesophyll cells.
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Affiliation(s)
- Michael Moison
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, Versailles, France
| | - Anne Marmagne
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, Versailles, France
| | - Sylvie Dinant
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, Versailles, France
| | - Fabienne Soulay
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, Versailles, France
| | - Marianne Azzopardi
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, Versailles, France
| | - Jérémy Lothier
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, Versailles, France
- Université de Versailles Saint Quentin en Yvelines, Université Paris Saclay, Versailles, France
| | - Sylvie Citerne
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, Versailles, France
| | - Halima Morin
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, Versailles, France
| | - Nicolas Legay
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, Versailles, France
- Université de Versailles Saint Quentin en Yvelines, Université Paris Saclay, Versailles, France
| | - Fabien Chardon
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, Versailles, France
| | - Jean-Christophe Avice
- UCBN, INRA, UMR INRA-UBCN Ecophysiologie Végétale, Agronomie and Nutrition N.C.S., Université de Caen Normandie, Caen, France
| | - Michèle Reisdorf-Cren
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, Versailles, France
- Université de Versailles Saint Quentin en Yvelines, Université Paris Saclay, Versailles, France
| | - Céline Masclaux-Daubresse
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, Versailles, France
- Correspondence:
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Konishi N, Saito M, Imagawa F, Kanno K, Yamaya T, Kojima S. Cytosolic Glutamine Synthetase Isozymes Play Redundant Roles in Ammonium Assimilation Under Low-Ammonium Conditions in Roots of Arabidopsis thaliana. PLANT & CELL PHYSIOLOGY 2018; 59:601-613. [PMID: 29373725 DOI: 10.1093/pcp/pcy014] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 01/17/2018] [Indexed: 05/26/2023]
Abstract
Ammonium is a major nitrogen source for plants; it is assimilated into glutamine via a reaction catalyzed by glutamine synthetase (GLN). Arabidopsis expresses four cytosolic GLN genes, GLN1; 1, GLN1; 2, GLN1; 3 and GLN1; 4, in roots. However, the function and organization of these GLN1 isozymes in ammonium assimilation in roots remain unclear. In this study, we aimed to characterize the four GLN1 isozymes. The levels of growth of the wild type and gln1 single and multiple knockout lines were compared in a hydroponic culture at ammonium concentrations of 0.1 and 3 mM. Under the low-ammonium concentration, in single mutants for each GLN1 gene, there was little effect on growth, whereas the triple mutant for GLN1; 1, GLN1; 2 and GLN1; 3 grew slowly and accumulated ammonium. Under the high-ammonium concentration, the single mutant for GLN1; 2 showed 50% decreases in fresh weight and glutamine, whereas the other gln1 single mutants did not show notable changes in the phenotype. The double mutant for GLN1; 1 and GLN1; 2 showed less growth and a lower glutamine concentration than the single mutant for GLN1; 2. Promoter analysis indicated an overlapping expression of GLN1; 1 with GLN1; 2 in the surface layers of the roots. We thus concluded that: (i) at a low concentration, ammonium was assimilated by GLN1; 1, GLN1; 2 and GLN1; 3, and they were redundant; (ii) low-affinity GLN1; 2 could contribute to ammonium assimilation at concentrations ranging from 0.1 to 3 mM; and (iii) GLN1; 1 supported GLN1; 2 within the outer cell layers of the root.
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Affiliation(s)
- Noriyuki Konishi
- Graduate School of Agricultural Science, Tohoku University, 468-1 Aoba, Aramaki, Sendai, 980-0845 Japan
- Division for Interdisciplinary Advanced Research and Education, Tohoku University, 6-3 Aoba, Aramaki, Sendai, 980-8578 Japan
| | - Masahide Saito
- Graduate School of Agricultural Science, Tohoku University, 468-1 Aoba, Aramaki, Sendai, 980-0845 Japan
| | - Fumi Imagawa
- Graduate School of Agricultural Science, Tohoku University, 468-1 Aoba, Aramaki, Sendai, 980-0845 Japan
| | - Keiich Kanno
- Graduate School of Agricultural Science, Tohoku University, 468-1 Aoba, Aramaki, Sendai, 980-0845 Japan
| | - Tomoyuki Yamaya
- Graduate School of Agricultural Science, Tohoku University, 468-1 Aoba, Aramaki, Sendai, 980-0845 Japan
| | - Soichi Kojima
- Graduate School of Agricultural Science, Tohoku University, 468-1 Aoba, Aramaki, Sendai, 980-0845 Japan
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Konishi N, Ishiyama K, Beier MP, Inoue E, Kanno K, Yamaya T, Takahashi H, Kojima S. Contributions of two cytosolic glutamine synthetase isozymes to ammonium assimilation in Arabidopsis roots. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:613-625. [PMID: 28007952 PMCID: PMC5441914 DOI: 10.1093/jxb/erw454] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Glutamine synthetase (GS) catalyzes a reaction that incorporates ammonium into glutamate and yields glutamine in the cytosol and chloroplasts. Although the enzymatic characteristics of the GS1 isozymes are well known, their physiological functions in ammonium assimilation and regulation in roots remain unclear. In this study we show evidence that two cytosolic GS1 isozymes (GLN1;2 and GLN1;3) contribute to ammonium assimilation in Arabidopsis roots. Arabidopsis T-DNA insertion lines for GLN1;2 and GLN1;3 (i.e. gln1;2 and gln1;3 single-mutants), the gln1;2:gln1;3 double-mutant, and the wild-type accession (Col-0) were grown in hydroponic culture with variable concentrations of ammonium to compare their growth, and their content of nitrogen, carbon, ammonium, and amino acids. GLN1;2 and GLN1;3 promoter-dependent green fluorescent protein was observed under conditions with or without ammonium supply. Loss of GLN1;2 caused significant suppression of plant growth and glutamine biosynthesis under ammonium-replete conditions. In contrast, loss of GLN1;3 caused slight defects in growth and Gln biosynthesis that were only visible based on a comparison of the gln1;2 single- and gln1;2:gln1;3 double-mutants. GLN1;2, being the most abundantly expressed GS1 isozyme, markedly increased following ammonium supply and its promoter activity was localized at the cortex and epidermis, while GLN1;3 showed only low expression at the pericycle, suggesting their different physiological contributions to ammonium assimilation in roots. The GLN1;2 promoter-deletion analysis identified regulatory sequences required for controlling ammonium-responsive gene expression of GLN1;2 in Arabidopsis roots. These results shed light on GLN1 isozyme-specific regulatory mechanisms in Arabidopsis that allow adaptation to an ammonium-replete environment.
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Affiliation(s)
- Noriyuki Konishi
- Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Sendai, Japan
| | - Keiki Ishiyama
- Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Sendai, Japan
- RIKEN Plant Science Center, Yokohama, Japan
| | - Marcel Pascal Beier
- Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Sendai, Japan
| | - Eri Inoue
- RIKEN Plant Science Center, Yokohama, Japan
| | - Keiichi Kanno
- Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Sendai, Japan
| | - Tomoyuki Yamaya
- Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Sendai, Japan
- RIKEN Plant Science Center, Yokohama, Japan
| | - Hideki Takahashi
- RIKEN Plant Science Center, Yokohama, Japan
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - Soichi Kojima
- Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Sendai, Japan
- RIKEN Plant Science Center, Yokohama, Japan
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Wang X, Wei Y, Shi L, Ma X, Theg SM. New isoforms and assembly of glutamine synthetase in the leaf of wheat (Triticum aestivum L.). JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:6827-34. [PMID: 26307137 PMCID: PMC4623691 DOI: 10.1093/jxb/erv388] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Glutamine synthetase (GS; EC 6.3.1.2) plays a crucial role in the assimilation and re-assimilation of ammonia derived from a wide variety of metabolic processes during plant growth and development. Here, three developmentally regulated isoforms of GS holoenzyme in the leaf of wheat (Triticum aestivum L.) seedlings are described using native-PAGE with a transferase activity assay. The isoforms showed different mobilities in gels, with GSII>GSIII>GSI. The cytosolic GSI was composed of three subunits, GS1, GSr1, and GSr2, with the same molecular weight (39.2kDa), but different pI values. GSI appeared at leaf emergence and was active throughout the leaf lifespan. GSII and GSIII, both located in the chloroplast, were each composed of a single 42.1kDa subunit with different pI values. GSII was active mainly in green leaves, while GSIII showed brief but higher activity in green leaves grown under field conditions. LC-MS/MS experiments revealed that GSII and GSIII have the same amino acid sequence, but GSII has more modification sites. With a modified blue native electrophoresis (BNE) technique and in-gel catalytic activity analysis, only two GS isoforms were observed: one cytosolic and one chloroplastic. Mass calibrations on BNE gels showed that the cytosolic GS1 holoenzyme was ~490kDa and likely a dodecamer, and the chloroplastic GS2 holoenzyme was ~240kDa and likely a hexamer. Our experimental data suggest that the activity of GS isoforms in wheat is regulated by subcellular localization, assembly, and modification to achieve their roles during plant development.
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Affiliation(s)
- Xiaochun Wang
- Collaborative Innovation Center of Henan Grain Crops, Henan Agriculture University, Zhengzhou 450002, China State Key Laboratory of Wheat and Maize Crop Science in China, Henan Agriculture University, Zhengzhou 450002, China Department of Biochemistry, College of Life Science, Henan Agriculture University, Zhengzhou 450002, China
| | - Yihao Wei
- Department of Biochemistry, College of Life Science, Henan Agriculture University, Zhengzhou 450002, China
| | - Lanxin Shi
- Department of Plant Biology, University of California-Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Xinming Ma
- Collaborative Innovation Center of Henan Grain Crops, Henan Agriculture University, Zhengzhou 450002, China
| | - Steven M Theg
- Department of Plant Biology, University of California-Davis, One Shields Avenue, Davis, CA 95616, USA
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Guan M, Møller IS, Schjoerring JK. Two cytosolic glutamine synthetase isoforms play specific roles for seed germination and seed yield structure in Arabidopsis. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:203-12. [PMID: 25316065 PMCID: PMC4265158 DOI: 10.1093/jxb/eru411] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Nitrogen (N) remobilization from reserves to sinks is essential for seedling establishment and seed production. Cytosolic glutamine synthetase (GS1) is up-regulated during both seed germination and seed filling in plants. However, the specific roles of the individual GS1 isogenes with respect to N remobilization, early seedling vigour, and final seed productivity are not known. In this study, impairment of seed germination and seedling establishment is demonstrated in the single knockout mutant gln1;2, and the double knockout mutant gln1;1:gln1;2. The negative effect of Gln1;2 deficiency was associated with reduced N remobilization from the cotyledons and could be fully alleviated by exogenous N supply. Following reproductive growth, both the single and double Gln1;2-knockout mutants showed decreased seed yield due to fewer siliques, less seeds per silique, and lower dry weight per seed. The gln1;1 single mutant had normal seed yield structure but primary root development during seed germination was reduced in the presence of external N. Gln1;2 promoter-green fluorescent protein constructs showed that Gln1;2 localizes to the vascular cells of roots, petals, and stamens. It is concluded that Gln1;2 plays an important role in N remobilization for both seedling establishment and seed production in Arabidopsis.
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Affiliation(s)
- M Guan
- Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
| | - I S Møller
- Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
| | - J K Schjoerring
- Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
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