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Yannam VRR, Caicedo M, Malvar RA, Ordás B. Genome-Wide Association Analysis of Senescence-Related Traits in Maize. Int J Mol Sci 2022; 23:ijms232415897. [PMID: 36555534 PMCID: PMC9782587 DOI: 10.3390/ijms232415897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 12/10/2022] [Accepted: 12/12/2022] [Indexed: 12/15/2022] Open
Abstract
Senescence is a programmed process that involves the destruction of the photosynthesis apparatus and the relocation of nutrients to the grain. Identifying senescence-associated genes is essential to adapting varieties for the duration of the cultivation cycle. A genome-wide association study (GWAS) was performed using 400 inbred maize lines with 156,164 SNPs to study the genetic architecture of senescence-related traits and their relationship with agronomic traits. We estimated the timing of senescence to be 45 days after anthesis in the whole plant and specifically in the husks. A list of genes identified in a previous RNAseq experiment as involved in senescence (core senescence genes) was used to propose candidate genes in the vicinity of the significant SNPs. Forty-six QTLs of moderate to high effect were found for senescence traits, including specific QTLs for husk senescence. The allele that delayed senescence primarily increased grain yield and moisture. Seven and one significant SNPs were found in the coding and promoter regions of eight core senescence genes, respectively. These genes could be potential candidates for generating a new variation by genome editing for functional analysis and breeding purposes, particularly Zm00001d014796, which could be responsible for a QTL of senescence found in multiple studies.
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Affiliation(s)
- Venkata Rami Reddy Yannam
- Mision Biológica de Galicia, Spanish National Research Council (CSIC), 36001 Pontevedra, Spain
- Sustainable Field Crops Programme, IRTA (Institute for Food and Agricultural Research and Technology), 25198 Lleida, Spain
| | - Marlon Caicedo
- Estación Experimental Tropical Pichilingue, Programa de Maíz, Instituto Nacional de Investigaciones Agropecuarias (INIAP), Quito 170518, Ecuador
| | - Rosa Ana Malvar
- Mision Biológica de Galicia, Spanish National Research Council (CSIC), 36001 Pontevedra, Spain
| | - Bernardo Ordás
- Mision Biológica de Galicia, Spanish National Research Council (CSIC), 36001 Pontevedra, Spain
- Correspondence:
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A New Perspective on the Role of Glutamine Synthetase in Nitrogen Remobilization in Wheat ( Triticum aestivum L.). Int J Mol Sci 2021; 22:ijms222011083. [PMID: 34681741 PMCID: PMC8539157 DOI: 10.3390/ijms222011083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2021] [Revised: 10/10/2021] [Accepted: 10/11/2021] [Indexed: 12/05/2022] Open
Abstract
Glutamine synthetase (GS), a key enzyme in plant nitrogen metabolism, is closely related to nitrogen remobilization. However, how GS isoforms participate in nitrogen remobilization remains unclear. Here, the spatiotemporal expression of the TaGS gene family after anthesis was investigated, and the results showed that TaGS1;1 was mainly encoded by TaGS1;1-6A, while the other isozymes were mainly encoded by TaGS localized on the A and D subgenomes. TaGS1;2-4A/4D had the highest expression level, especially in rachis and peduncle. Furthermore, immunofluorescence showed TaGS1;2 was located in the phloem of rachis and peduncle. GUS (β-glucuronidase) staining confirmed that ProTaGS1;2-4A/4D::GUS activity was mainly present in the vascular system of leaves, roots, and petal of Arabidopsis. Ureides, an important transport form of nitrogen, were mainly synthesized in flag leaves and transported to grains through the phloem of peduncle and rachis during grain filling. TaAAH, which encodes the enzyme that degrades ureides to release NH4+, had a higher expression in rachis and peduncle and was synchronized with the increase in NH4+ concentration in phloem, indicating that NH4+ in phloem is from ureide degradation. Taking the above into account, TaGS1;2, which is highly expressed in the phloem of peduncle and rachis, may participate in N remobilization by assimilating NH4+ released from ureide degradation.
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Fiaz S, Wang X, Khan SA, Ahmar S, Noor MA, Riaz A, Ali K, Abbas F, Mora-Poblete F, Figueroa CR, Alharthi B. Novel plant breeding techniques to advance nitrogen use efficiency in rice: A review. GM CROPS & FOOD 2021; 12:627-646. [PMID: 34034628 PMCID: PMC9208628 DOI: 10.1080/21645698.2021.1921545] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Recently, there has been a remarkable increase in rice production owing to genetic improvement and increase in application of synthetic fertilizers. For sustainable agriculture, there is dire need to maintain a balance between profitability and input cost. To meet the steady growing demands of the farming community, researchers are utilizing all available resources to identify nutrient use efficient germplasm, but with very little success. Therefore, it is essential to understand the underlying genetic mechanism controlling nutrients efficiency, with the nitrogen use efficiency (NUE) being the most important trait. Information regarding genetic factors controlling nitrogen (N) transporters, assimilators, and remobilizers can help to identify candidate germplasms via high-throughput technologies. Large-scale field trials have provided morphological, physiological, and biochemical trait data for the detection of genomic regions controlling NUE. The functional aspects of these attributes are time-consuming, costly, labor-intensive, and less accurate. Therefore, the application of novel plant breeding techniques (NPBTs) with context to genome engineering has opened new avenues of research for crop improvement programs. Most recently, genome editing technologies (GETs) have undergone enormous development with various versions from Cas9, Cpf1, base, and prime editing. These GETs have been vigorously adapted in plant sciences for novel trait development to insure food quantity and quality. Base editing has been successfully applied to improve NUE in rice, demonstrating the potential of GETs to develop germplasms with improved resource use efficiency. NPBTs continue to face regulatory setbacks in some countries due to genome editing being categorized in the same category as genetically modified (GM) crops. Therefore, it is essential to involve all stakeholders in a detailed discussion on NPBTs and to formulate uniform policies tackling biosafety, social, ethical, and environmental concerns. In the current review, we have discussed the genetic mechanism of NUE and NPBTs for crop improvement programs with proof of concepts, transgenic and GET application for the development of NUE germplasms, and regulatory aspects of genome edited crops with future directions considering NUE.
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Affiliation(s)
- Sajid Fiaz
- Department of Plant Breeding and Genetics, The University of Haripur 22620, Khyber, Pakhtunkhwa, Pakistan
| | - Xiukang Wang
- College of Life Sciences, Yan'an University, Yan'an, Shaanxi, China
| | - Sher Aslam Khan
- Department of Plant Breeding and Genetics, The University of Haripur 22620, Khyber, Pakhtunkhwa, Pakistan
| | - Sunny Ahmar
- Institute of Biological Sciences, Campus Talca, Universidad deTalca, Talca, Chile
| | - Mehmood Ali Noor
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Key Laboratory of Crop Physiology and Ecology, Ministry of Agriculture, Beijing, China
| | - Aamir Riaz
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, Zhejiang, China
| | - Kazim Ali
- National Institute for Genomics and Advanced Biotechnology, National Agricultural Research Centre, Islamabad, Pakistan
| | - Farhat Abbas
- Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
| | - Freddy Mora-Poblete
- Institute of Biological Sciences, Campus Talca, Universidad deTalca, Talca, Chile
| | - Carlos R Figueroa
- Institute of Biological Sciences, Campus Talca, Universidad deTalca, Talca, Chile
| | - Badr Alharthi
- College of Khurma, Taif University, Taif, Saudi Arabia.,College of Science and Engineering, Flinders University, Adelaide, South Australia
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Gupta N, Gupta M, Akhatar J, Goyal A, Kaur R, Sharma S, Goyal P, Mukta A, Kaur N, Mittal M, Singh MP, Bharti B, Sardana VK, Banga SS. Association genetics of the parameters related to nitrogen use efficiency in Brassica juncea L. PLANT MOLECULAR BIOLOGY 2021; 105:161-175. [PMID: 32997301 DOI: 10.1007/s11103-020-01076-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 09/23/2020] [Indexed: 06/11/2023]
Abstract
Genome wide association studies allowed prediction of 17 candidate genes for association with nitrogen use efficiency. Novel information obtained may provide better understanding of genomic controls underlying germplasm variations for this trait in Indian mustard. Nitrogen use efficiency (NUE) of Indian mustard (Brassica juncea (L.) Czern & Coss.) is low and most breeding efforts to combine NUE with crop performance have not succeeded. Underlying genetics also remain unexplored. We tested 92 SNP-genotyped inbred lines for yield component traits, N uptake efficiency (NUPEFF), nitrogen utilization efficiency (NUTEFF), nitrogen harvest index (NHI) and NUE for two years at two nitrogen doses (No without added N and N100 added @100 kg/ha). Genotypes IC-2489-88, M-633, MCP-632, HUJM 1080, GR-325 and DJ-65 recorded high NUE at low N. These also showed improved crop performance under high N. One determinate mustard genotype DJ-113 DT-3 revealed maximum NUTEFF. Genome wide association studies (GWAS) facilitated recognition of 17 quantitative trait loci (QTLs). Environment specificity was high. B-genome chromosomes (B02, B03, B05, B07 and B08) harbored many useful loci. We also used regional association mapping (RAM) to supplement results from GWAS. Annotation of the genomic regions around peak SNPs helped to predict several gene candidates for root architecture, N uptake, assimilation and remobilization. CAT9 (At1g05940) was consistently envisaged for both NUE and NUPEFF. Major N transporter genes, NRT1.8 and NRT3.1 were predicted for explaining variation for NUTEFF and NUPEFF, respectively. Most significant amino acid transporter gene, AAP1 appeared associated with NUE under limited N conditions. All these candidates were predicted in the regions of high linkage disequilibrium. Sequence information of the predicted candidate genes will permit development of molecular markers to aid breeding for high NUE.
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Affiliation(s)
- Neha Gupta
- Department of Plant Breeding and Genetics, Punjab Agricultural University, Punjab, 141004, Ludhiana, India
| | - Mehak Gupta
- Department of Plant Breeding and Genetics, Punjab Agricultural University, Punjab, 141004, Ludhiana, India
| | - Javed Akhatar
- Department of Plant Breeding and Genetics, Punjab Agricultural University, Punjab, 141004, Ludhiana, India
| | - Anna Goyal
- Department of Plant Breeding and Genetics, Punjab Agricultural University, Punjab, 141004, Ludhiana, India
| | - Rimaljeet Kaur
- Department of Plant Breeding and Genetics, Punjab Agricultural University, Punjab, 141004, Ludhiana, India
| | - Sanjula Sharma
- Department of Plant Breeding and Genetics, Punjab Agricultural University, Punjab, 141004, Ludhiana, India
| | - Prinka Goyal
- Department of Plant Breeding and Genetics, Punjab Agricultural University, Punjab, 141004, Ludhiana, India
| | - Archana Mukta
- Department of Plant Breeding and Genetics, Punjab Agricultural University, Punjab, 141004, Ludhiana, India
| | - Navneet Kaur
- Department of Plant Breeding and Genetics, Punjab Agricultural University, Punjab, 141004, Ludhiana, India
| | - Meenakshi Mittal
- Department of Plant Breeding and Genetics, Punjab Agricultural University, Punjab, 141004, Ludhiana, India
| | - Mohini Prabha Singh
- Department of Plant Breeding and Genetics, Punjab Agricultural University, Punjab, 141004, Ludhiana, India
| | - Baudh Bharti
- Department of Plant Breeding and Genetics, Punjab Agricultural University, Punjab, 141004, Ludhiana, India
| | - V K Sardana
- Department of Plant Breeding and Genetics, Punjab Agricultural University, Punjab, 141004, Ludhiana, India
| | - Surinder S Banga
- Department of Plant Breeding and Genetics, Punjab Agricultural University, Punjab, 141004, Ludhiana, India.
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Michailidis M, Karagiannis E, Tanou G, Sarrou E, Stavridou E, Ganopoulos I, Karamanoli K, Madesis P, Martens S, Molassiotis A. An integrated metabolomic and gene expression analysis identifies heat and calcium metabolic networks underlying postharvest sweet cherry fruit senescence. PLANTA 2019; 250:2009-2022. [PMID: 31531781 DOI: 10.1007/s00425-019-03272-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Accepted: 09/05/2019] [Indexed: 05/22/2023]
Abstract
Ηeat and calcium treatments reprogram sweet cherry fruit metabolism during postharvest senescence as evidenced by changes in respiration, amino acid metabolism, sugars, and secondary metabolites shift. Heat and calcium treatments are used to improve postharvest fruit longevity; however, the exact mechanism remains poorly understood. To characterize the impact of these treatments on sweet cherries metabolism, 'Lapins' fruits were treated with heat or CaCl2 solutions and their combination and subsequently were exposed at room temperature, for up to 4 days, defined as senescence period. Single and combined heat and calcium treatments partially delayed fruit senescence, as evidenced by changes in fruit colour darkening, skin penetration force, and respiration activity. Calcium content was noticeably increased by heat in Ca-treated fruit. Several primary metabolites, including amino acids, organic acids, and alcohols, were decreased in response to both treatments, while many soluble sugars and secondary metabolites were increased within 1 day post-treatment. Changes of several metabolites in heat-treated fruits, especially esculetin, peonidin 3-O-glucoside and peonidin 3-O-galactoside, ribose, pyroglutamate, and isorhamnetin-3-O-rutinoside, were detected. The metabolome of fruit exposed to calcium also displayed substantial modulations, particularly in the levels of galactose, glycerate, aspartate, tryptophan, phospharate rutin, and peonidin 3-O-glucoside. The expression of several genes involved in TCA cycle (MDH1, IDH1, OGDH, SUCLA2, and SDH1-1), pectin degradation (ADPG1) as well as secondary (SK1, 4CL1, HCT, and BAN), amino acids (ALDH18A1, ALDH4A1, GS, GAD, GOT2, OPLAH, HSDH, and SDS), and sugar (PDHA1 and DLAT) metabolism were affected by both treatments. Pathway-specific analysis further revealed the regulation of fruit metabolic programming by heat and calcium. This work provides a comprehensive understanding of metabolic regulation in response to heat and calcium during fruit senescence.
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Affiliation(s)
- Michail Michailidis
- Laboratory of Pomology, School of Agriculture, Aristotle University of Thessaloniki, Thermi, 57001, Thessaloniki, Greece
| | - Evangelos Karagiannis
- Laboratory of Pomology, School of Agriculture, Aristotle University of Thessaloniki, Thermi, 57001, Thessaloniki, Greece
| | - Georgia Tanou
- Institute of Soil and Water Resources, ELGO-DEMETER, 57001, Thessaloníki, Greece
| | - Eirini Sarrou
- Institute of Plant Breeding and Genetic Resources, ELGO-DEMETER, 57001, Thessaloníki, Greece
| | | | - Ioannis Ganopoulos
- Institute of Plant Breeding and Genetic Resources, ELGO-DEMETER, 57001, Thessaloníki, Greece
| | - Katerina Karamanoli
- Laboratory of Agricultural Chemistry, School of Agriculture, Aristotle University of Thessaloniki, Thessaloníki, 54124, Greece
| | | | - Stefan Martens
- Department of Food Quality and Nutrition, Centro Ricerca E Innovazione, Fondazione Edmund Mach, San Michele All'adige, 38010, Trento, Italy
| | - Athanassios Molassiotis
- Laboratory of Pomology, School of Agriculture, Aristotle University of Thessaloniki, Thermi, 57001, Thessaloniki, Greece.
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Nitrogen Supply and Leaf Age Affect the Expression of TaGS1 or TaGS2 Driven by a Constitutive Promoter in Transgenic Tobacco. Genes (Basel) 2018; 9:genes9080406. [PMID: 30103455 PMCID: PMC6115907 DOI: 10.3390/genes9080406] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 08/01/2018] [Accepted: 08/07/2018] [Indexed: 11/26/2022] Open
Abstract
Glutamine synthetase (GS) plays a key role in nitrogen metabolism. Here, two types of tobacco transformants, overexpressing Triticum aestivum GS1 (TaGS1) or GS2 (TaGS2), were analysed. Four independent transformed lines, GS1-TR1, GS1-TR2, GS2-TR1 and GS2-TR2, were used for the nitrogen treatment. Under nitrogen-sufficient conditions, the leaves of GS2-TR showed high accumulation of the TaGS2 transcript, while those of GS1-TR showed a low TaGS1 transcript levels. However, compared with nitrogen-sufficient conditions, the TaGS1 transcript level increased in the leaves under nitrogen starvation, but the TaGS2 transcript level decreased. In addition, the TaGS1 and TaGS2 transcript levels were highest in the middle leaves under nitrogen-sufficient and starvation conditions. These results show that nitrogen supply and leaf age regulate TaGS expression, even when they are driven by a super-promoter. Additionally, in regard to nitrogen metabolism level, the lower leaves of the GS1-TR exhibited lower NH4+ and higher amino acid contents, while the upper leaves exhibited higher amino acid, soluble protein and chlorophyll contents. The leaves of the GS2-TR exhibited lower NH4+ but higher amino acid, soluble protein and chlorophyll contents. Given the role that GS isoforms play in nitrogen metabolism, these data suggest that TaGS1 overexpression may improve nitrogen transport, and that TaGS2 overexpression may improve nitrogen assimilation under nitrogen stress.
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Tegeder M, Masclaux-Daubresse C. Source and sink mechanisms of nitrogen transport and use. THE NEW PHYTOLOGIST 2018; 217:35-53. [PMID: 29120059 DOI: 10.1111/nph.14876] [Citation(s) in RCA: 303] [Impact Index Per Article: 50.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 09/09/2017] [Indexed: 05/03/2023]
Abstract
Contents Summary 35 I. Introduction 35 II. Nitrogen acquisition and assimilation 36 III. Root-to-shoot transport of nitrogen 38 IV. Nitrogen storage pools in vegetative tissues 39 V. Nitrogen transport from source leaf to sink 40 VI. Nitrogen import into sinks 42 VII. Relationship between source and sink nitrogen transport processes and metabolism 43 VIII. Regulation of nitrogen transport 43 IX. Strategies for crop improvement 44 X. Conclusions 46 Acknowledgements 47 References 47 SUMMARY: Nitrogen is an essential nutrient for plant growth. World-wide, large quantities of nitrogenous fertilizer are applied to ensure maximum crop productivity. However, nitrogen fertilizer application is expensive and negatively affects the environment, and subsequently human health. A strategy to address this problem is the development of crops that are efficient in acquiring and using nitrogen and that can achieve high seed yields with reduced nitrogen input. This review integrates the current knowledge regarding inorganic and organic nitrogen management at the whole-plant level, spanning from nitrogen uptake to remobilization and utilization in source and sink organs. Plant partitioning and transient storage of inorganic and organic nitrogen forms are evaluated, as is how they affect nitrogen availability, metabolism and mobilization. Essential functions of nitrogen transporters in source and sink organs and their importance in regulating nitrogen movement in support of metabolism, and vegetative and reproductive growth are assessed. Finally, we discuss recent advances in plant engineering, demonstrating that nitrogen transporters are effective targets to improve crop productivity and nitrogen use efficiency. While inorganic and organic nitrogen transporters were examined separately in these studies, they provide valuable clues about how to successfully combine approaches for future crop engineering.
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Affiliation(s)
- Mechthild Tegeder
- School of Biological Sciences, Washington State University, Pullman, WA, 99164-4236, USA
| | - Céline Masclaux-Daubresse
- INRA-AgroParisTech, Institut Jean-Pierre Bourgin, UMR1318, ERL CNRS 3559, Saclay Plant Sciences, Versailles, France
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Zeng W, Sun Z, Cai Z, Chen H, Lai Z, Yang S, Tang X. Proteomic analysis by iTRAQ-MRM of soybean resistance to Lamprosema Indicate. BMC Genomics 2017; 18:444. [PMID: 28587595 PMCID: PMC5461738 DOI: 10.1186/s12864-017-3825-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 05/28/2017] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Lamprosema indicate is a major leaf feeding insect pest to soybean, which has caused serious yield losses in central and southern China. To explore the defense mechanisms of soybean resistance to Lamprosema indicate, a highly resistant line (Gantai-2-2) and a highly susceptible line (Wan 82-178) were exposed to Lamprosema indicate larval feedings for 0 h and 48 h, and the differential proteomic analyses of these two lines were carried out. RESULTS The results showed that 31 differentially expressed proteins (DEPs) were identified in the Gantai-2-2 when comparing 48 h feeding with 0 h feeding, and 53 DEPs were identified in the Wan 82-178. 28 DEPs were identified when comparing Gantai-2-2 with Wan 82-178 at 0 h feeding. The bioinformatic analysis results showed that most of the DEPs were associated with ribosome, linoleic acid metabolism, flavonoid biosynthesis, phenylpropanoid biosynthesis, peroxisome, stilbenoid, diarylheptanoid and gingerol biosynthesis, glutathione metabolism, pant hormone signal transduction, and flavone and flavonol biosynthesis, as well as other resistance related metabolic pathways. The MRM analysis showed that the iTRAQ results were reliable. CONCLUSIONS According to the analysis of the DEPs results, the soybean defended or resisted the Lamprosema indicate damage by the induction of a synthesis of anti-digestive proteins which inhibit the growth and development of insects, reactive oxygen species scavenging, signaling pathways, secondary metabolites synthesis, and so on.
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Affiliation(s)
- Weiying Zeng
- Guangxi Academy of Agricultural Sciences, Nanning, Guangxi 530007 China
| | - Zudong Sun
- Guangxi Academy of Agricultural Sciences, Nanning, Guangxi 530007 China
| | - Zhaoyan Cai
- Guangxi Academy of Agricultural Sciences, Nanning, Guangxi 530007 China
| | - Huaizhu Chen
- Guangxi Academy of Agricultural Sciences, Nanning, Guangxi 530007 China
| | - Zhenguang Lai
- Guangxi Academy of Agricultural Sciences, Nanning, Guangxi 530007 China
| | - Shouzhen Yang
- Guangxi Academy of Agricultural Sciences, Nanning, Guangxi 530007 China
| | - Xiangmin Tang
- Guangxi Academy of Agricultural Sciences, Nanning, Guangxi 530007 China
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Li Y, Wang M, Zhang F, Xu Y, Chen X, Qin X, Wen X. Effect of post-silking drought on nitrogen partitioning and gene expression patterns of glutamine synthetase and asparagine synthetase in two maize (Zea mays L.) varieties. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2016; 102:62-9. [PMID: 26913793 DOI: 10.1016/j.plaphy.2016.02.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 01/25/2016] [Accepted: 02/03/2016] [Indexed: 05/08/2023]
Abstract
Glutamine synthetase (GS) and asparagine synthetase (AS) are proposed to have important function in plant nitrogen (N) remobilization, but their roles under drought stress are not well defined. In this study, the expression dynamics of GS and AS genes were analyzed in two maize varieties (ZD958 and NH101) in relation to post-silking drought stress induced nitrogen partitioning. ZD958 was a 'stay-green' variety with 5% nitrogen harvest index (NHI) lower than NH101. From silking to maturity, the amount of nitrogen remobilized from ear-leaves in ZD958 was evidently lower than NH101, and post-silking drought stress increased the nitrogen remobilization for both varieties. In ear-leaves, the expression of ZmGln1-3 was enhanced under drought stress. Three AS genes (ZmAS1, ZmAS2 and ZmAS3) were differentially regulated by post-silking drought treatment, of which the expression of ZmAS3 was stimulated at late stage of leaf senescence. In NH101, the expression level of ZmAS3 was markedly higher than that in ZD958. In developing grains, there were no significant differences in expression patterns of GS and AS genes between well water and drought treated plants. Drought stress altered maize N partitioning at the whole-plant level, and the up-regulation of GS and AS genes may contribute to the higher leaf nitrogen remobilization when exposed to drought treatments.
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Affiliation(s)
- Yajun Li
- College of Agronomy, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Meiling Wang
- College of Agronomy, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Fengxia Zhang
- College of Agronomy, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Yadong Xu
- College of Agronomy, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Xiaohong Chen
- College of Agronomy, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Xiaoliang Qin
- College of Agronomy, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Xiaoxia Wen
- College of Agronomy, Northwest A&F University, Yangling, Shaanxi, 712100, China.
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Uzelac B, Janošević D, Simonović A, Motyka V, Dobrev PI, Budimir S. Characterization of natural leaf senescence in tobacco (Nicotiana tabacum) plants grown in vitro. PROTOPLASMA 2016; 253:259-75. [PMID: 25837009 DOI: 10.1007/s00709-015-0802-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 03/14/2015] [Indexed: 05/18/2023]
Abstract
Leaf senescence is a highly regulated final phase of leaf development preceding massive cell death. It results in the coordinated degradation of macromolecules and the subsequent nutrient relocation to other plant parts. Very little is still known about early stages of leaf senescence during normal leaf ontogeny that is not triggered by stress factors. This paper comprises an integrated study of natural leaf senescence in tobacco plants grown in vitro, using molecular, structural, and physiological information. We determined the time sequence of ultrastructural changes in mesophyll cells during leaf senescence, showing that the degradation of chloroplast ultrastructure fully correlated with changes in chlorophyll content. The earliest degenerative changes in chloroplast ultrastructure coinciding with early chromatin condensation were observed already in mature green leaves. A continuum of degradative changes in chloroplast ultrastructure, chromatin condensation and aggregation, along with progressive decrease in cytoplasm organization and electron density were observed in the course of mesophyll cells ageing. Although the total amounts of endogenous cytokinins gradually increased during leaf ontogenesis, the proportion of bioactive cytokinin forms, as well as their phosphate precursors, in total cytokinin content rapidly declined with ageing. Endogenous indole-3-acetic acid (IAA) levels were strongly reduced in senescent leaves, and a decreasing tendency was also observed for abscisic acid (ABA) levels. Senescence-associated tobacco cysteine proteases (CP, E.C. 3.4.22) CP1 and CP23 genes were induced in the initial phase of senescence. Genes encoding glutamate dehydrogenase (GDH, E.C. 1.4.1.2) and one isoform of cytosolic glutamine synthetase (GS1, E.C. 6.3.1.2) were induced in the late stage of senescence, while chloroplastic GS (GS2) gene showed a continuous decrease with leaf ageing.
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Affiliation(s)
- Branka Uzelac
- Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, Belgrade, Serbia.
| | - Dušica Janošević
- Institute of Botany and Botanical Garden "Jevremovac", Faculty of Biology, University of Belgrade, Takovska 43, Belgrade, Serbia
| | - Ana Simonović
- Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, Belgrade, Serbia
| | - Václav Motyka
- Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Rozvojova 263, 16502, Praha 6, Czech Republic
| | - Petre I Dobrev
- Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Rozvojova 263, 16502, Praha 6, Czech Republic
| | - Snežana Budimir
- Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, Belgrade, Serbia
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Moschen S, Bengoa Luoni S, Di Rienzo JA, Caro MDP, Tohge T, Watanabe M, Hollmann J, González S, Rivarola M, García-García F, Dopazo J, Hopp HE, Hoefgen R, Fernie AR, Paniego N, Fernández P, Heinz RA. Integrating transcriptomic and metabolomic analysis to understand natural leaf senescence in sunflower. PLANT BIOTECHNOLOGY JOURNAL 2016; 14:719-34. [PMID: 26132509 DOI: 10.1111/pbi.12422] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 05/12/2015] [Accepted: 05/25/2015] [Indexed: 05/20/2023]
Abstract
Leaf senescence is a complex process, which has dramatic consequences on crop yield. In sunflower, gap between potential and actual yields reveals the economic impact of senescence. Indeed, sunflower plants are incapable of maintaining their green leaf area over sustained periods. This study characterizes the leaf senescence process in sunflower through a systems biology approach integrating transcriptomic and metabolomic analyses: plants being grown under both glasshouse and field conditions. Our results revealed a correspondence between profile changes detected at the molecular, biochemical and physiological level throughout the progression of leaf senescence measured at different plant developmental stages. Early metabolic changes were detected prior to anthesis and before the onset of the first senescence symptoms, with more pronounced changes observed when physiological and molecular variables were assessed under field conditions. During leaf development, photosynthetic activity and cell growth processes decreased, whereas sucrose, fatty acid, nucleotide and amino acid metabolisms increased. Pathways related to nutrient recycling processes were also up-regulated. Members of the NAC, AP2-EREBP, HB, bZIP and MYB transcription factor families showed high expression levels, and their expression level was highly correlated, suggesting their involvement in sunflower senescence. The results of this study thus contribute to the elucidation of the molecular mechanisms involved in the onset and progression of leaf senescence in sunflower leaves as well as to the identification of candidate genes involved in this process.
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Affiliation(s)
- Sebastián Moschen
- Instituto de Biotecnología, Centro de Investigaciones en Ciencias Agronómicas y Veterinarias, Instituto Nacional de Tecnología Agropecuaria, Hurlingham, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, Argentina
| | - Sofía Bengoa Luoni
- Escuela de Ciencia y Tecnología, Universidad Nacional de San Martín, San Martín, Argentina
| | - Julio A Di Rienzo
- Facultad de Ciencias Agropecuarias, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - María Del Pilar Caro
- Instituto Superior de Investigaciones Biológicas, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de Tucumán, San Miguel de Tucumán, Argentina
| | - Takayuki Tohge
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Potsdam-Golm, Germany
| | - Mutsumi Watanabe
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Potsdam-Golm, Germany
| | - Julien Hollmann
- Institute of Botany, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Sergio González
- Instituto de Biotecnología, Centro de Investigaciones en Ciencias Agronómicas y Veterinarias, Instituto Nacional de Tecnología Agropecuaria, Hurlingham, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, Argentina
| | - Máximo Rivarola
- Instituto de Biotecnología, Centro de Investigaciones en Ciencias Agronómicas y Veterinarias, Instituto Nacional de Tecnología Agropecuaria, Hurlingham, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, Argentina
| | - Francisco García-García
- Department of Bioinformatics and Genomics, Centro de Investigación Príncipe Felipe, Valencia, España
- Functional Genomics Node, National Institute of Bioinformatics, Centro de Investigación Príncipe Felipe, Valencia, España
| | - Joaquin Dopazo
- Department of Bioinformatics and Genomics, Centro de Investigación Príncipe Felipe, Valencia, España
- Functional Genomics Node, National Institute of Bioinformatics, Centro de Investigación Príncipe Felipe, Valencia, España
| | - Horacio Esteban Hopp
- Instituto de Biotecnología, Centro de Investigaciones en Ciencias Agronómicas y Veterinarias, Instituto Nacional de Tecnología Agropecuaria, Hurlingham, Argentina
- Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina
| | - Rainer Hoefgen
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Potsdam-Golm, Germany
| | - Alisdair R Fernie
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Potsdam-Golm, Germany
| | - Norma Paniego
- Instituto de Biotecnología, Centro de Investigaciones en Ciencias Agronómicas y Veterinarias, Instituto Nacional de Tecnología Agropecuaria, Hurlingham, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, Argentina
| | - Paula Fernández
- Instituto de Biotecnología, Centro de Investigaciones en Ciencias Agronómicas y Veterinarias, Instituto Nacional de Tecnología Agropecuaria, Hurlingham, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, Argentina
- Escuela de Ciencia y Tecnología, Universidad Nacional de San Martín, San Martín, Argentina
| | - Ruth A Heinz
- Instituto de Biotecnología, Centro de Investigaciones en Ciencias Agronómicas y Veterinarias, Instituto Nacional de Tecnología Agropecuaria, Hurlingham, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, Argentina
- Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina
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12
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Avila-Ospina L, Marmagne A, Talbotec J, Krupinska K, Masclaux-Daubresse C. The identification of new cytosolic glutamine synthetase and asparagine synthetase genes in barley (Hordeum vulgare L.), and their expression during leaf senescence. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:2013-26. [PMID: 25697791 PMCID: PMC4378633 DOI: 10.1093/jxb/erv003] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 12/17/2014] [Accepted: 12/19/2014] [Indexed: 05/18/2023]
Abstract
Glutamine synthetase and asparagine synthetase are two master enzymes involved in ammonium assimilation in plants. Their roles in nitrogen remobilization and nitrogen use efficiency have been proposed. In this report, the genes coding for the cytosolic glutamine synthetases (HvGS1) and asparagine synthetases (HvASN) in barley were identified. In addition to the three HvGS1 and two HvASN sequences previously reported, two prokaryotic-like HvGS1 and three HvASN cDNA sequences were identified. Gene structures were then characterized, obtaining full genomic sequences. The response of the five HvGS1 and five HvASN genes to leaf senescence was then studied. Developmental senescence was studied using primary and flag leaves. Dark-exposure or low-nitrate conditions were also used to trigger stress-induced senescence. Well-known senescence markers such as the chlorophyll and Rubisco contents were monitored in order to characterize senescence levels in the different leaves. The three eukaryotic-like HvGS1_1, HvGS1_2, and HvGS1_3 sequences showed the typical senescence-induced reduction in gene expression described in many plant species. By contrast, the two prokaryotic-like HvGS1_4 and HvGS1_5 sequences were repressed by leaf senescence, similar to the HvGS2 gene, which encodes the chloroplast glutamine synthetase isoenzyme. There was a greater contrast in the responses of the five HvASN and this suggested that these genes are needed for N remobilization in senescing leaves only when plants are well fertilized with nitrate. Responses of the HvASN sequences to dark-induced senescence showed that there are two categories of asparagine synthetases, one induced in the dark and the other repressed by the same conditions.
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Affiliation(s)
- Liliana Avila-Ospina
- INRA, UMR1318, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France AgroParisTech, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France
| | - Anne Marmagne
- INRA, UMR1318, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France AgroParisTech, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France
| | - Joël Talbotec
- INRA, UMR1318, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France AgroParisTech, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France
| | - Karin Krupinska
- Institute of Botany, Christian-Albrechts-University of Kiel, Olshausenstraße 40, D-24098 Kiel, Germany
| | - Céline Masclaux-Daubresse
- INRA, UMR1318, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France AgroParisTech, Institut Jean-Pierre Bourgin, RD10, F-78000 Versailles, France
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13
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Thomsen HC, Eriksson D, Møller IS, Schjoerring JK. Cytosolic glutamine synthetase: a target for improvement of crop nitrogen use efficiency? TRENDS IN PLANT SCIENCE 2014; 19:656-63. [PMID: 25017701 DOI: 10.1016/j.tplants.2014.06.002] [Citation(s) in RCA: 137] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 05/30/2014] [Accepted: 06/02/2014] [Indexed: 05/19/2023]
Abstract
Overexpression of the cytosolic enzyme glutamine synthetase 1 (GS1) has been investigated in numerous cases with the goal of improving crop nitrogen use efficiency. However, the outcome has generally been inconsistent. Here, we review possible reasons underlying the lack of success and conclude that GS1 activity may be downregulated via a chain of processes elicited by metabolic imbalances and environmental constraints. We suggest that a pivotal role of GS1 may be related to the maintenance of essential nitrogen (N) flows and internal N sensing during critical stages of plant development. A number of more refined overexpression strategies exploiting gene stacking combined with tissue and cell specific targeting to overcome metabolic bottlenecks are considered along with their potential in relation to new N management strategies.
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Affiliation(s)
- Hanne C Thomsen
- Department of Plant and Environmental Sciences, Plant and Soil Science Section, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark
| | - Dennis Eriksson
- Department of Plant and Environmental Sciences, Plant and Soil Science Section, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark
| | - Inge S Møller
- Department of Plant and Environmental Sciences, Plant and Soil Science Section, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark
| | - Jan K Schjoerring
- Department of Plant and Environmental Sciences, Plant and Soil Science Section, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark.
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14
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Large-scale protein analysis of European beech trees following four vegetation periods of twice ambient ozone exposure. J Proteomics 2014; 109:417-35. [DOI: 10.1016/j.jprot.2014.05.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 03/24/2014] [Accepted: 05/01/2014] [Indexed: 01/02/2023]
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15
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Lee HJ, Abdula SE, Jang DW, Park SH, Yoon UH, Jung YJ, Kang KK, Nou IS, Cho YG. Overexpression of the glutamine synthetase gene modulates oxidative stress response in rice after exposure to cadmium stress. PLANT CELL REPORTS 2013; 32:1521-9. [PMID: 23743654 DOI: 10.1007/s00299-013-1464-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 05/14/2013] [Accepted: 05/23/2013] [Indexed: 05/23/2023]
Abstract
Overexpression of OsGS gene modulates oxidative stress response in rice after exposure to cadmium stress. Our results describe the features of transformants with enhanced tolerance to Cd and abiotic stresses. Glutamine synthetase (GS) (EC 6.3.1.2) is an enzyme that plays an essential role in the metabolism of nitrogen by catalyzing the condensation of glutamate and ammonia to form glutamine. Exposure of plants to cadmium (Cd) has been reported to decrease GS activity in maize, pea, bean, and rice. To better understand the function of the GS gene under Cd stress in rice, we constructed a recombinant pART vector carrying the GS gene under the control of the CaMV 35S promoter and OCS terminator and transformed using Agrobacterium tumefaciens. We then investigated GS overexpressing rice lines at the physiological and molecular levels under Cd toxicity and abiotic stress conditions. We observed a decrease in GS enzyme activity and mRNA expression among transgenic and wild-type plants subjected to Cd stress. The decrease, however, was significantly lower in the wild type than in the transgenic plants. This was further validated by the high GS mRNA expression and enzyme activity in most of the transgenic lines. Moreover, after 10 days of exposure to Cd stress, increase in the glutamine reductase activity and low or no malondialdehyde contents were observed. These results showed that overexpression of the GS gene in rice modulated the expression of enzymes responsible for membrane peroxidation that may result in plant death.
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Affiliation(s)
- Hye Jung Lee
- Department of Crop Science, Chungbuk National University, Cheongju, 361-763, Korea
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16
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Grassl J, Pružinská A, Hörtensteiner S, Taylor NL, Millar AH. Early events in plastid protein degradation in stay-green Arabidopsis reveal differential regulation beyond the retention of LHCII and chlorophyll. J Proteome Res 2012; 11:5443-52. [PMID: 23025280 DOI: 10.1021/pr300691k] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
An individually darkened leaf model was used to study protein changes in the Arabidopsis mutant stay-green1 (sgr1) to partially mimic the process of leaf covering senescence that occurs naturally in the shaded rosettes of Arabidopsis plants. Utilizing this controlled and predictable induced senescence model has allowed the direct comparison of sgr1 with Col-0 during the developmental period preceding the retention of chlorophyll and light harvesting complex II (LHCII) in sgr1 and the induction of senescence in Col-0. Quantitative proteomic analysis of soluble leaf proteins from sgr1 and Col-0 before the initiation of senescence has revealed a range of differences in plastid soluble protein abundance in sgr1 when compared to Col-0. Changes were also observed in membrane located machinery for photosystem II (PSII), in Calvin cycle components, proteins involved in redox control of the stromal compartment and ammonia assimilation that differentiated sgr1 during the early stages of the senescence process. The changes in PSII abundance were accompanied with a lower capacity of photosynthetic CO(2) assimilation in sgr1 than Col-0 after return of plants to lighted conditions following 3 and 5 days of darkness. A light-harvesting chlorophyll-a/b binding protein (LHCB2) was retained during the later stages of senescence in sgr1 but this was accompanied by an enhanced loss of oxygen evolving complex (OEC) subunits from PSII, which was confirmed by Western blotting, and an enhanced stability of PSII repair proteins in sgr1, compared to Col-0. Together these data provide insights into the significant differences in the steady-state proteome in sgr1 and its response to senescence, showing this cosmetic stay-green mutant is in fact significantly different to wild-type plants both before and during leaf senescence.
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Affiliation(s)
- Julia Grassl
- ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Western Australia, Australia
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17
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Khanna-Chopra R. Leaf senescence and abiotic stresses share reactive oxygen species-mediated chloroplast degradation. PROTOPLASMA 2012; 249:469-81. [PMID: 21805384 DOI: 10.1007/s00709-011-0308-z] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Accepted: 07/19/2011] [Indexed: 05/18/2023]
Abstract
Leaf senescence is a genetically programmed decline in various cellular processes including photosynthesis and involves the hydrolysis of macromolecules such as proteins, lipids, etc. It is governed by the developmental age and is induced or enhanced by environmental stresses such as drought, heat, salinity and others. Internal factors such as reproductive structures also influence the rate of leaf senescence. Reactive oxygen species (ROS) generation is one of the earliest responses of plant cells under abiotic stresses and senescence. Chloroplasts are the main targets of ROS-linked damage during various environmental stresses and natural senescence as ROS detoxification systems decline with age. Plants adapt to environmental stresses through the process of acclimation, which involves less ROS production coupled with an efficient antioxidant defence. Chloroplasts are a major site of protein degradation, and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is rapidly and selectively degraded during senescence and stress. The process of protein degradation is initiated by ROS and involves the action of proteolytic enzymes such as cysteine and serine proteases. The mechanism of Rubisco degradation still remains to be elucidated. The molecular understanding of leaf senescence was achieved through the characterization of senescence-associated genes and various senescence mutants of Arabidopsis, which is a suitable model plant showing monocarpic senescence. The regulation of senescence involves many regulatory elements composed of positive and negative elements to fine-tune the initiation and progression of senescence. This review gives an overview on chloroplast protein degradation during leaf senescence and abiotic stresses and also highlights the role of ROS management in both processes.
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Affiliation(s)
- Renu Khanna-Chopra
- Stress Physiology and Biochemistry Laboratory, Water Technology Centre, Indian Agricultural Research Institute, New Delhi, 110012, India.
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18
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Galant A, Koester RP, Ainsworth EA, Hicks LM, Jez JM. From climate change to molecular response: redox proteomics of ozone-induced responses in soybean. THE NEW PHYTOLOGIST 2012; 194:220-229. [PMID: 22272738 DOI: 10.1111/j.1469-8137.2011.04037.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
• Ozone (O₃) causes significant agricultural losses, with soybean (Glycine max) being highly sensitive to this oxidant. Here we assess the effect of elevated seasonal O₃ exposure on the total and redox proteomes of soybean. • To understand the molecular responses to O₃ exposure, soybean grown at the Soybean Free Air Concentration Enrichment facility under ambient (37 ppb), moderate (58 ppb), and high (116 ppb) O₃ concentrations was examined by redox-sensitive thiol labeling, mass spectrometry, and targeted enzyme assays. • Proteomic analysis of soybean leaf tissue exposed to high O₃ concentrations reveals widespread changes. In the high-O₃ treatment leaf, 35 proteins increased up to fivefold in abundance, 22 proteins showed up to fivefold higher oxidation, and 22 proteins increased in both abundance and oxidation. These changes occurred in carbon metabolism, photosynthesis, amino acid synthesis, flavonoid and isoprenoid biosynthesis, signaling and homeostasis, and antioxidant pathways. • This study shows that seasonal O₃ exposure in soybean alters the abundance and oxidation state of redox-sensitive multiple proteins and that these changes reflect a combination of damage effects and adaptive responses that influence a wide range of metabolic processes, which in some cases may help mitigate oxidative stress.
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Affiliation(s)
- Ashley Galant
- Department of Biology, Washington University, One Brookings Drive, Campus Box 1137, St. Louis, MO 63130, USA
| | - Robert P Koester
- Department of Plant Biology, 1201 West Gregory Drive, MC-051, University of Illinois, Urbana-Champaign, Urbana, IL 61801, USA
| | - Elizabeth A Ainsworth
- Department of Plant Biology, 1201 West Gregory Drive, MC-051, University of Illinois, Urbana-Champaign, Urbana, IL 61801, USA
- USDA-ARS Global Change and Photosynthesis Research Unit, 1201 West Gregory Drive, MC-051, Urbana, IL 61801, USA
| | - Leslie M Hicks
- Donald Danforth Plant Science Center, 975 North Warson Road, St. Louis, MO 63132, USA
| | - Joseph M Jez
- Department of Biology, Washington University, One Brookings Drive, Campus Box 1137, St. Louis, MO 63130, USA
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19
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Linka M, Weber APM. Evolutionary Integration of Chloroplast Metabolism with the Metabolic Networks of the Cells. FUNCTIONAL GENOMICS AND EVOLUTION OF PHOTOSYNTHETIC SYSTEMS 2012. [DOI: 10.1007/978-94-007-1533-2_8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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20
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Castro-Rodríguez V, García-Gutiérrez A, Canales J, Avila C, Kirby EG, Cánovas FM. The glutamine synthetase gene family in Populus. BMC PLANT BIOLOGY 2011; 11:119. [PMID: 21867507 PMCID: PMC3224142 DOI: 10.1186/1471-2229-11-119] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Accepted: 08/25/2011] [Indexed: 05/20/2023]
Abstract
BACKGROUND Glutamine synthetase (GS; EC: 6.3.1.2, L-glutamate: ammonia ligase ADP-forming) is a key enzyme in ammonium assimilation and metabolism of higher plants. The current work was undertaken to develop a more comprehensive understanding of molecular and biochemical features of GS gene family in poplar, and to characterize the developmental regulation of GS expression in various tissues and at various times during the poplar perennial growth. RESULTS The GS gene family consists of 8 different genes exhibiting all structural and regulatory elements consistent with their roles as functional genes. Our results indicate that the family members are organized in 4 groups of duplicated genes, 3 of which code for cytosolic GS isoforms (GS1) and 1 which codes for the choroplastic GS isoform (GS2). Our analysis shows that Populus trichocarpa is the first plant species in which it was observed the complete GS family duplicated. Detailed expression analyses have revealed specific spatial and seasonal patterns of GS expression in poplar. These data provide insights into the metabolic function of GS isoforms in poplar and pave the way for future functional studies. CONCLUSIONS Our data suggest that GS duplicates could have been retained in order to increase the amount of enzyme in a particular cell type. This possibility could contribute to the homeostasis of nitrogen metabolism in functions associated to changes in glutamine-derived metabolic products. The presence of duplicated GS genes in poplar could also contribute to diversification of the enzymatic properties for a particular GS isoform through the assembly of GS polypeptides into homo oligomeric and/or hetero oligomeric holoenzymes in specific cell types.
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Affiliation(s)
- Vanessa Castro-Rodríguez
- Departamento de Biología Molecular y Bioquímica, Instituto Andaluz de Biotecnología, Universidad de Málaga, 29071-Málaga, Spain
| | - Angel García-Gutiérrez
- Departamento de Biología Molecular y Bioquímica, Instituto Andaluz de Biotecnología, Universidad de Málaga, 29071-Málaga, Spain
| | - Javier Canales
- Departamento de Biología Molecular y Bioquímica, Instituto Andaluz de Biotecnología, Universidad de Málaga, 29071-Málaga, Spain
| | - Concepción Avila
- Departamento de Biología Molecular y Bioquímica, Instituto Andaluz de Biotecnología, Universidad de Málaga, 29071-Málaga, Spain
| | - Edward G Kirby
- Department of Biological Sciences, Rutgers University, Newark, New Jersey 07102, USA
| | - Francisco M Cánovas
- Departamento de Biología Molecular y Bioquímica, Instituto Andaluz de Biotecnología, Universidad de Málaga, 29071-Málaga, Spain
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21
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Keech O, Pesquet E, Gutierrez L, Ahad A, Bellini C, Smith SM, Gardeström P. Leaf senescence is accompanied by an early disruption of the microtubule network in Arabidopsis. PLANT PHYSIOLOGY 2010; 154:1710-20. [PMID: 20966154 PMCID: PMC2996031 DOI: 10.1104/pp.110.163402] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2010] [Accepted: 10/18/2010] [Indexed: 05/18/2023]
Abstract
The dynamic assembly and disassembly of microtubules (MTs) is essential for cell function. Although leaf senescence is a well-documented process, the role of the MT cytoskeleton during senescence in plants remains unknown. Here, we show that both natural leaf senescence and senescence of individually darkened Arabidopsis (Arabidopsis thaliana) leaves are accompanied by early degradation of the MT network in epidermis and mesophyll cells, whereas guard cells, which do not senesce, retain their MT network. Similarly, entirely darkened plants, which do not senesce, retain their MT network. While genes encoding the tubulin subunits and the bundling/stabilizing MT-associated proteins (MAPs) MAP65 and MAP70-1 were repressed in both natural senescence and dark-induced senescence, we found strong induction of the gene encoding the MT-destabilizing protein MAP18. However, induction of MAP18 gene expression was also observed in leaves from entirely darkened plants, showing that its expression is not sufficient to induce MT disassembly and is more likely to be part of a Ca(2+)-dependent signaling mechanism. Similarly, genes encoding the MT-severing protein katanin p60 and two of the four putative regulatory katanin p80s were repressed in the dark, but their expression did not correlate with degradation of the MT network during leaf senescence. Taken together, these results highlight the earliness of the degradation of the cortical MT array during leaf senescence and lead us to propose a model in which suppression of tubulin and MAP genes together with induction of MAP18 play key roles in MT disassembly during senescence.
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Affiliation(s)
- Olivier Keech
- Australian Research Council Centre of Excellence in Plant Energy Biology and Centre of Excellence for Plant Metabolomics, University of Western Australia, Crawley, Western Australia 6009, Australia.
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22
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Simon B, Sengupta-Gopalan C. The 3' untranslated region of the two cytosolic glutamine synthetase (GS(1)) genes in alfalfa (Medicago sativa) regulates transcript stability in response to glutamine. PLANTA 2010; 232:1151-62. [PMID: 20706735 DOI: 10.1007/s00425-010-1247-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2010] [Accepted: 07/28/2010] [Indexed: 05/20/2023]
Abstract
Glutamine synthetase (GS) catalyzes the ATP-dependent condensation of ammonia with glutamate to produce glutamine. The GS enzyme is located either in the chloroplast (GS(2)) or in the cytoplasm (GS(1)). GS(1) is encoded by a small gene family and the members exhibit differential expression pattern mostly attributed to transcriptional regulation. Based on our recent finding that a soybean GS(1) gene, Gmglnβ ( 1 ) is subject to its 3'UTR-mediated post-transcriptional regulation as a transgene in alfalfa (Medicago sativa) we have raised the question of whether the 3'UTR-mediated transcript destabilization is a more universal phenomenon. Gene constructs consisting of the CaMV35S promoter driving the reporter gene, GUS, followed by the 3'UTRs of the two alfalfa GS(1) genes, MsGSa and MsGSb, were introduced into alfalfa and tobacco. The analysis of these transformants suggests that while both the 3'UTRs promote transcript turnover, the MsGSb 3'UTR is more effective than the MsGSa 3'UTR. However, both the 3'UTRs along with Gmglnβ ( 1 ) 3'UTR respond to nitrate as a trigger in transcript turnover. More detailed analysis points to glutamine rather than nitrate as the mediator of transcript turnover. Our data suggests that the 3'UTR-mediated regulation of GS(1) genes at the level of transcript turnover is probably universal and is used for fine-tuning the expression in keeping with the availability of the substrates.
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Affiliation(s)
- Bindu Simon
- New Mexico State University, Las Cruces, NM 88003, USA
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23
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Couturier J, Doidy J, Guinet F, Wipf D, Blaudez D, Chalot M. Glutamine, arginine and the amino acid transporter Pt-CAT11 play important roles during senescence in poplar. ANNALS OF BOTANY 2010; 105:1159-69. [PMID: 20237111 PMCID: PMC2887068 DOI: 10.1093/aob/mcq047] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
BACKGROUND AND AIMS Nitrogen (N) availability in the forest soil is extremely low and N economy has a special importance in woody plants that are able to cope with seasonal periods of growth and development over many years. Here we report on the analysis of amino acid pools and expression of key genes in the perennial species Populus trichocarpa during autumn senescence. METHODS Amino acid pools were measured throughout senescence. Expression analysis of arginine synthesis genes and cationic amino acid transporter (CAT) genes during senescence was performed. Heterologous expression in yeast mutants was performed to study Pt-CAT11 function in detail. KEY RESULTS Analysis of amino acid pools showed an increase of glutamine in leaves and an accumulation of arginine in stems during senescence. Expression of arginine biosynthesis genes suggests that arginine was preferentially synthesized from glutamine in perennial tissues. Pt-CAT11 expression increased in senescing leaves and functional characterization demonstrated that Pt-CAT11 transports glutamine. CONCLUSIONS The present study established a relationship between glutamine synthesized in leaves and arginine synthesized in stems during senescence, arginine being accumulated as an N storage compound in perennial tissues such as stems. In this context, Pt-CAT11 may have a key role in N remobilization during senescence in poplar, by facilitating glutamine loading into phloem vessels.
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Affiliation(s)
- Jérémy Couturier
- UMR INRA/UHP 1136 ‘Interactions Arbre-Microorganismes’, Faculté des Sciences et Techniques, Nancy-Université, BP 70239, F-54506 Vandoeuvre-les-Nancy Cedex, France
- For correspondence. E-mail
| | - Joan Doidy
- UMR INRA 1088/CNRS 5184/Université Bourgogne, Plante-Microbe-Environnement, INRA-CMSE, BP 86510, 21065 Dijon Cedex, France
| | - Frédéric Guinet
- UMR INRA/UHP 1136 ‘Interactions Arbre-Microorganismes’, Faculté des Sciences et Techniques, Nancy-Université, BP 70239, F-54506 Vandoeuvre-les-Nancy Cedex, France
| | - Daniel Wipf
- UMR INRA 1088/CNRS 5184/Université Bourgogne, Plante-Microbe-Environnement, INRA-CMSE, BP 86510, 21065 Dijon Cedex, France
| | - Damien Blaudez
- UMR INRA/UHP 1136 ‘Interactions Arbre-Microorganismes’, Faculté des Sciences et Techniques, Nancy-Université, BP 70239, F-54506 Vandoeuvre-les-Nancy Cedex, France
| | - Michel Chalot
- UMR INRA/UHP 1136 ‘Interactions Arbre-Microorganismes’, Faculté des Sciences et Techniques, Nancy-Université, BP 70239, F-54506 Vandoeuvre-les-Nancy Cedex, France
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Broyart C, Fontaine JX, Molinié R, Cailleu D, Tercé-Laforgue T, Dubois F, Hirel B, Mesnard F. Metabolic profiling of maize mutants deficient for two glutamine synthetase isoenzymes using 1H-NMR-based metabolomics. PHYTOCHEMICAL ANALYSIS : PCA 2010; 21:102-9. [PMID: 19866455 DOI: 10.1002/pca.1177] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
INTRODUCTION Maize mutants deficient for the expression of two genes encoding cytosolic glutamine synthetase (GS) isoenzymes GS1.3 and GS1.4 displayed reduced kernel number and kernel size, respectively, the effect of the mutation being cumulative in the double mutant. However, at maturity, shoot biomass production was not modified in all the mutants, indicating that the reaction catalysed by the enzyme is specifically involved in the control of grain yield. OBJECTIVE To examine the physiological impact of the GS mutations on the leaf metabolic profile during the kernel filling period, during which nitrogen is remobilized from the shoots to be further exported to the kernels. METHODOLOGY An (1)H-NMR spectroscopy metabolomic was applied to the investigation of metabolic change of the gln1.3, gln1.4 and gln1.3/1.4 double mutant. RESULTS In the three GS mutants, an increase in the amount of several N-containing metabolites such as asparagine, alanine, threonine and phophatidylcholine was observed whatever the level of nitrogen fertilisation. In addition, we found an accumulation of phenylalanine and tyrosine, two metabolites involved the primary steps of the phenylpropanoid pathway. CONCLUSION Changes in the metabolic profile of the GS mutants suggest that, when cytosolic GS activity is strongly reduced, either alternative metabolic pathways participate in the reassimilation of ammonium released during leaf protein remobilization or that premature leaf senescence is induced when kernel set and kernel filling are affected. The accumulation of phenylalanine and tyrosine in the mutant plants indicates that lignin biosynthesis is altered, thus possibly affecting ear development.
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Affiliation(s)
- Caroline Broyart
- EA 3900-BioPI Biologie des Plantes et Contrôle des Insectes Ravageurs, Faculté de Pharmacie, 1, rue des Louvels et Faculté des Sciences, 33, rue Saint Leu, 80037 Amiens cedex 1, France
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Seger M, Ortega JL, Bagga S, Gopalan CS. Repercussion of mesophyll-specific overexpression of a soybean cytosolic glutamine synthetase gene in alfalfa ( Medicago sativa L.) and tobacco ( Nicotiana tabaccum L.). PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2009; 176:119-129. [PMID: 25067868 PMCID: PMC4108266 DOI: 10.1016/j.plantsci.2008.10.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Glutamine synthetase (GS) plays a central role in plant nitrogen metabolism. Plant GS occurs as a number of isoenzymes present in either the cytosol (GS1) or chloroplast/plastid (GS2). There are several reports of improved performance in transgenic plants overexpressing GS1 transgenes driven by the constitutive CaMV35S promoter. Improvement has been attributed to the GS1 transgene product functioning to enhance re-assimilation of NH4+ released by photorespiration or protein degradation. In this paper, alfalfa and tobacco transformants expressing a soybean gene driven by a photosynthetic cell-specific promoter have been compared to transformants with the same transgene driven by the stronger CaMV35S promoter. The two classes of alfalfa and tobacco transformants showed differences in the level of GS1 transcript and GS1 protein accumulation, but the difference in the total GS activity was small. The discrepancy in the transgene expression level and GS activity has been attributed to posttranslational regulation at the level of holoprotein stability. Both classes of transformants exhibited similar level of improvement in soluble protein and in the rates of photosynthesis and photorespiration. The data supports the hypothesis that GS1 made in the mesophyll cells is involved in the re-assimilation of NH4+ released via photorespiration and/or protein degradation.
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Affiliation(s)
- Mark Seger
- Graduate Program in Molecular Biology, New Mexico State University, 945 College Ave, MSC-3Q, Las Cruces, NM 88003 USA
| | - Jose Luis Ortega
- Department of Plant and Environmental Sciences, New Mexico State University, 945 College Ave, MSC-3Q, Las Cruces, NM 88003 USA
| | - Suman Bagga
- Department of Plant and Environmental Sciences, New Mexico State University, 945 College Ave, MSC-3Q, Las Cruces, NM 88003 USA
| | - Champa-Sengupta Gopalan
- Graduate Program in Molecular Biology, New Mexico State University, 945 College Ave, MSC-3Q, Las Cruces, NM 88003 USA
- Department of Plant and Environmental Sciences, New Mexico State University, 945 College Ave, MSC-3Q, Las Cruces, NM 88003 USA
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Bernard SM, Habash DZ. The importance of cytosolic glutamine synthetase in nitrogen assimilation and recycling. THE NEW PHYTOLOGIST 2009; 182:608-620. [PMID: 19422547 DOI: 10.1111/j.1469-8137.2009.02823.x] [Citation(s) in RCA: 285] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Glutamine synthetase assimilates ammonium into amino acids, thus it is a key enzyme for nitrogen metabolism. The cytosolic isoenzymes of glutamine synthetase assimilate ammonium derived from primary nitrogen uptake and from various internal nitrogen recycling pathways. In this way, cytosolic glutamine synthetase is crucial for the remobilization of protein-derived nitrogen. Cytosolic glutamine synthetase is encoded by a small family of genes that are well conserved across plant species. Members of the cytosolic glutamine synthetase gene family are regulated in response to plant nitrogen status, as well as to environmental cues, such as nitrogen availability and biotic/abiotic stresses. The complex regulation of cytosolic glutamine synthetase at the transcriptional to post-translational levels is key to the establishment of a specific physiological role for each isoenzyme. The diverse physiological roles of cytosolic glutamine synthetase isoenzymes are important in relation to current agricultural and ecological issues.
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Affiliation(s)
- Stéphanie M Bernard
- Earth Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA
| | - Dimah Z Habash
- Plant Science Department, Centre for Crop Genetic Improvement, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, UK
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Masclaux-Daubresse C, Reisdorf-Cren M, Orsel M. Leaf nitrogen remobilisation for plant development and grain filling. PLANT BIOLOGY (STUTTGART, GERMANY) 2008; 10 Suppl 1:23-36. [PMID: 18721309 DOI: 10.1111/j.1438-8677.2008.00097.x] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
A major challenge of modern agriculture is to reduce the excessive input of fertilisers and, at the same time, to improve grain quality without affecting yield. One way to achieve this goal is to improve plant nitrogen economy through manipulating nitrogen recycling, and especially nitrogen remobilisation, from senescing plant organs. In this review, the contribution of nitrogen remobilisation efficiency (NRE) to global nitrogen use efficiency (NUE), and tools dedicated to the determination of NRE are described. An overall examination of the physiological, metabolic and genetic aspects of nitrogen remobilisation is presented.
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Affiliation(s)
- C Masclaux-Daubresse
- Unité de Nutrition Azotée des Plantes, Institut National de la Recherche Agronomique, Route de Saint Cyr, Versailles, France.
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Yajun H, Wangzhen G, Xinlian S, Tianzhen Z. Molecular cloning and characterization of a cytosolic glutamine synthetase gene, a fiber strength-associated gene in cotton. PLANTA 2008; 228:473-83. [PMID: 18560885 DOI: 10.1007/s00425-008-0751-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2008] [Accepted: 05/08/2008] [Indexed: 05/12/2023]
Abstract
An expressed sequence tag encoding glutamine synthetase (GS) was identified by microarray-based hybridization using fiber mRNAs of allotetraploid Gossypium hirsutum, 7235, a super quality property germplasm line, and TM-1, a genetic standard in G. hirsutum. Northern-blot analysis verified transcript accumulation differences in 8 DPA fibers (including ovules) in the two varieties. The full-length cDNA encoding GS in 7235 was isolated and named GhGS. Sequence analysis revealed that the GhGS was similar to cytosolic GS. Southern-blot analysis showed that tetraploid cotton contained at least one copy of the A sub-genome and the D sub-genome. Genomic GhGS sequences were subsequently isolated from different varieties, TM-1, 7235 and two diploid progenitor cottons, G. herbaceum (A-genome) and G. raimondii (D-genome). Molecular mapping and single-marker analysis revealed that the GhGS was significantly correlated with fiber strength and was mapped to chromosome D7. Additionally, GS activities and total protein of the ovules and the fibers were assayed. The results showed a significantly higher GS activity in 7235 seeds compared to TM-1 seeds at 5 and 8 DPA. Also significant differences were found in total protein content and seed weight at 11 DPA. This suggested that GS promoted the seed-forming process by providing N. On the other hand, in fibers, GS activity and total protein assay indicated a lower total GS activity and longer fiber elongation period in 7235. These results suggest that the respective roles of the GS in ovules and fibers do not completely overlap.
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Affiliation(s)
- He Yajun
- National Key Laboratory of Crop Genetics and Germplasm Enhancement, Cotton Research Institute, Nanjing Agricultural University, Nanjing, 210095, Jiangsu Province, China
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Lemaître T, Gaufichon L, Boutet-Mercey S, Christ A, Masclaux-Daubresse C. Enzymatic and metabolic diagnostic of nitrogen deficiency in Arabidopsis thaliana Wassileskija accession. PLANT & CELL PHYSIOLOGY 2008; 49:1056-65. [PMID: 18508804 DOI: 10.1093/pcp/pcn081] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Adaptation to steady-state low-nutrient availability was investigated by comparing the Wassileskija (WS) accession of Arabidopsis thaliana grown on 2 or 10 mM nitrate. Low nitrogen conditions led to a limited rosette biomass and seed yield. The latter was mainly due to reduced seed number, while seed weight was less affected. However, harvest index was lower in high nitrate compared with limited nitrate conditions. Under nitrogen-limiting conditions, nitrate reductase activity was decreased while glutamine synthetase activity was increased due to a higher accumulation of the cytosolic enzyme. The level of nitrogen remobilization to the seeds was higher under low nitrogen, and the vegetative parts of the plants remaining after seed production stored very low residual nitrogen. Through promoting nitrogen remobilization and recycling pathways, nitrogen limitation modified plant and seed compositions. Rosette leaves contained more sugars and less free amino acids when grown under nitrogen-limiting conditions. Compared with high nitrogen, the levels of proline, asparagine and glutamine were decreased. The seed amino acid composition reflected that of the rosette leaves, thus suggesting that phloem loading for seed filling was poorly selective. The major finding of this report was that together with decreasing biomass and yield, nitrogen limitation triggers large modifications in vegetative products and seed quality.
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Affiliation(s)
- Thomas Lemaître
- Unité de Nutrition Azotée des Plantes, UNAP, UR511, INRA, Route de Saint Cyr, F-78000 Versailles, France
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Bohler S, Bagard M, Oufir M, Planchon S, Hoffmann L, Jolivet Y, Hausman JF, Dizengremel P, Renaut J. A DIGE analysis of developing poplar leaves subjected to ozone reveals major changes in carbon metabolism. Proteomics 2007; 7:1584-99. [PMID: 17486556 DOI: 10.1002/pmic.200600822] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Tropospheric ozone pollution is described as having major negative effects on plants, compromising plant survival. Carbon metabolism is especially affected. In the present work, the effects of chronic ozone exposure were evaluated at the proteomic level in developing leaves of young poplar plants exposed to 120 ppb of ozone for 35 days. Soluble proteins (excluding intrinsic membrane proteins) were extracted from leaves after 3, 14 and 35 days of ozone exposure, as well as 10 days after a recovery period. Proteins (pI 4 to 7) were analyzed by 2-D DIGE experiments, followed by MALDI-TOF-TOF identification. Additional observations were obtained on growth, lesion formation, and leaf pigments analysis. Although treated plants showed large necrotic spots and chlorosis in mature leaves, growth decreased only slightly and plant height was not affected. The number of abscised leaves was higher in treated plants, but new leaf formation was not affected. A decrease in chlorophylls and lutein contents was recorded. A large number of proteins involved in carbon metabolism were identified. In particular, proteins associated with the Calvin cycle and electron transport in the chloroplast were down-regulated. In contrast, proteins associated with glucose catabolism increased in response to ozone exposure. Other identified enzymes are associated with protein folding, nitrogen metabolism and oxidoreductase activity.
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Affiliation(s)
- Sacha Bohler
- Centre de Recherche Public--Gabriel Lippmann, Département Environnement et Agrobiotechnologies, Belvaux, Luxembourg
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Couturier J, Montanini B, Martin F, Brun A, Blaudez D, Chalot M. The expanded family of ammonium transporters in the perennial poplar plant. THE NEW PHYTOLOGIST 2007; 174:137-150. [PMID: 17335504 DOI: 10.1111/j.1469-8137.2007.01992.x] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
* Ammonium and nitrate are the prevalent nitrogen sources for growth and development of higher plants. Here, we report on the characterization of the ammonium transporter (AMT) family in the perennial species Populus trichocarpa. * In silico analysis and expression analysis of AMT genes from poplar was performed. In addition, AMT1;2 and AMT1;6 function was studied in detail by heterologous expression in yeast. * The P. trichocarpa genome contains 14 putative AMTs, which is more than twice the number of AMTs in Arabidopsis. In roots, the high-affinity AMT1;2 strongly increased upon mycorrhiza formation and might be partly responsible for the high-affinity ammonium uptake component measured in poplar. Transcript level for the high-affinity AMT1;6 was strongly affected by the diurnal cycle. AMT3;1 was exclusively expressed in senescing poplar leaves. Remarkably AMT2;1 was highly expressed in leaves while AMT2;2 was mostly expressed in petioles. Specific expression of AMT1;5 in stamen and of AMT1;6 in female flower indicate that they have key functions in reproductive organ development in poplar. * The present study provides basic genomic and transcriptomic information for the poplar AMT family and will pave the way for deciphering the precise role of AMTs in poplar physiology.
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Affiliation(s)
- Jérémy Couturier
- Research Unit INRA/UHP 1136 'Tree-microbe Interactions', Nancy-University, BP 239, F-54506 Vandoeuvre-les-Nancy Cedex, France
| | - Barbara Montanini
- Research Unit INRA/UHP 1136 'Tree-microbe Interactions', Nancy-University, BP 239, F-54506 Vandoeuvre-les-Nancy Cedex, France
| | - Francis Martin
- Research Unit INRA/UHP 1136 'Tree-microbe Interactions', Nancy-University, BP 239, F-54506 Vandoeuvre-les-Nancy Cedex, France
| | - Annick Brun
- Research Unit INRA/UHP 1136 'Tree-microbe Interactions', Nancy-University, BP 239, F-54506 Vandoeuvre-les-Nancy Cedex, France
| | - Damien Blaudez
- Research Unit INRA/UHP 1136 'Tree-microbe Interactions', Nancy-University, BP 239, F-54506 Vandoeuvre-les-Nancy Cedex, France
| | - Michel Chalot
- Research Unit INRA/UHP 1136 'Tree-microbe Interactions', Nancy-University, BP 239, F-54506 Vandoeuvre-les-Nancy Cedex, France
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Lopes MS, Cortadellas N, Kichey T, Dubois F, Habash DZ, Araus JL. Wheat nitrogen metabolism during grain filling: comparative role of glumes and the flag leaf. PLANTA 2006; 225:165-81. [PMID: 16804706 DOI: 10.1007/s00425-006-0338-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2005] [Accepted: 05/26/2006] [Indexed: 05/02/2023]
Abstract
The mobilization of nitrogen (N) compounds and the roles played by glumes and the flag leaf during grain filling were studied in bread wheat (Triticum aestivum L. cv. Florida) grown under field conditions. Glumes lost twice as much of their total N content as that lost by the flag leaf between the milk and early dough stages. In the flag leaf, glumes and grains, Glu, Asp, Ser and Ala accounted for 85% of all the reductions in the free amino acid pool. Principal component analysis of free amino acid pools separated grains from the glumes and the flag leaf, suggesting grain specific regulations in the use of free amino acids in protein synthesis. In all three organs, no decrease in Gln was detected, probably due to steady glutamine synthetase (GS; EC 6.3.1.2) activities per soluble protein in both the flag leaf and glumes. Compared with the flag leaf, glumes presented relatively smaller amounts of the chloroplast GS associated isoform. This we show is due to a lower relative number of mesophyll cells in glumes as supported by the different anatomy and the cellular pattern of the GS immunolocalization. We argue that cellular distribution plays a key role in supporting metabolism to enable the various functions undertaken by glume tissue.
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Affiliation(s)
- Marta S Lopes
- Unitat de Fisiologia Vegetal, Facultat de Biologia, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain
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Almeida AM, Santos M, Villalobos E, Araújo SS, van Dijck P, Leyman B, Cardoso LA, Santos D, Fevereiro PS, Torné JM. Immunogold localization of trehalose-6-phosphate synthase in leaf segments of wild-type and transgenic tobacco plants expressing the AtTPS1 gene from Arabidopsis thaliana. PROTOPLASMA 2006; 230:41-9. [PMID: 17111094 DOI: 10.1007/s00709-006-0198-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2005] [Accepted: 03/21/2006] [Indexed: 05/12/2023]
Abstract
Following the establishment of a transgenic line of tobacco (B5H) expressing the trehalose-6-phosphate synthase (TPS) gene from Arabidopsis thaliana, a preliminary immunolocalization study was conducted using leaves of adequately watered B5H and wild-type plants. Immunocytochemical staining, followed by electron microscopy showed that the enzyme could be detected in both B5H and wild-type plants at two different levels. Quantification showed the signal to be two to three times higher in transgenic plants than in the wild type. This enzyme was markedly present in the vacuoles and the cell wall, and to a lesser extent in the cytosol. Moreover, a high profusion of gold particles was detected in adjacent cells and in the sieve elements. Occasional spots were also detected in chloroplasts and the nucleus, especially in the transgenic B5H line. No labeling signal was detected in mitochondria. Protein localization seems to confirm the important role of TPS in sugar metabolism and transport through the plant, which could explain its role in plant stress tolerance. Finally, it can be expected that TPS from tobacco has a relatively high similarity to the TPS of Arabidopsis thaliana.
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Affiliation(s)
- A M Almeida
- Laboratório de Biotecnologia de Células Vegetais, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal.
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Pourtau N, Jennings R, Pelzer E, Pallas J, Wingler A. Effect of sugar-induced senescence on gene expression and implications for the regulation of senescence in Arabidopsis. PLANTA 2006; 224:556-68. [PMID: 16514542 DOI: 10.1007/s00425-006-0243-y] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2005] [Accepted: 01/30/2006] [Indexed: 05/06/2023]
Abstract
There has been some debate whether leaf senescence is induced by sugar starvation or by sugar accumulation. External supply of sugars has been shown to induce symptoms of senescence such as leaf yellowing. However, it was so far not clear if sugars have a signalling function during developmental senescence. Glucose and fructose accumulate strongly during senescence in Arabidopsis thaliana (L.) Heynh. leaves. Using Affymetrix GeneChip analysis we determined the effect of sugar-induced senescence on gene expression. Growth on glucose in combination with low nitrogen supply induced leaf yellowing and changes in gene expression that are characteristic of developmental senescence. Most importantly, the senescence-specific gene SAG12, which was previously thought to be sugar-repressible, was induced over 900-fold by glucose. Induction of SAG12, which is expressed during late senescence, demonstrates that processes characteristic for late stages are sugar-inducible. Two MYB transcription factor genes, PAP1 and PAP2, were identified as senescence-associated genes that are induced by glucose. Moreover, growth on glucose induced genes for nitrogen remobilisation that are typically enhanced during developmental senescence, including the glutamine synthetase gene GLN1;4 and the nitrate transporter gene AtNRT2.5. In contrast to wild-type plants, the hexokinase-1 mutant gin2-1 did not accumulate hexoses and senescence was delayed. Induction of senescence by externally supplied glucose was partially abolished in gin2-1, indicating that delayed senescence was a consequence of decreased sugar sensitivity. Taken together, our results show that Arabidopsis leaf senescence is induced rather than repressed by sugars.
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Affiliation(s)
- Nathalie Pourtau
- Department of Biology, University College London, Gower Street, London WC1E 6BT, UK
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Pageau K, Reisdorf-Cren M, Morot-Gaudry JF, Masclaux-Daubresse C. The two senescence-related markers, GS1 (cytosolic glutamine synthetase) and GDH (glutamate dehydrogenase), involved in nitrogen mobilization, are differentially regulated during pathogen attack and by stress hormones and reactive oxygen species in Nicotiana tabacum L. leaves. JOURNAL OF EXPERIMENTAL BOTANY 2005; 57:547-57. [PMID: 16377736 DOI: 10.1093/jxb/erj035] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
To investigate the role of stress in nitrogen management in plants, the effect of pathogen attack, elicitors, and phytohormone application on the expression of the two senescence-related markers GS1 (cytosolic glutamine synthetase EC 6.3.1.2) and GDH (glutamate dehydrogenase, EC 1.4.1.2) involved in nitrogen mobilization in senescing leaves of tobacco (Nicotiana tabacum L.) plants, was studied. The expression of genes involved in primary nitrogen assimilation such as GS2 (chloroplastic glutamine synthetase) and Nia (nitrate reductase, EC 1.6.1.1) was also analysed. The Glubas gene, coding a beta-1,3-glucanase, was used as a plant-defence gene control. As during natural senescence, the expression of GS2 and Nia was repressed under almost all stress conditions. By contrast, GS1 and GDH mRNA accumulation was increased. However, GS1 and GDH showed differential patterns of expression depending on the stress applied. The expression of GS1 appeared more selective than GDH. Results indicate that the GDH and GS1 genes involved in leaf senescence are also a component of the plant defence response during plant-pathogen interaction. The links between natural plant senescence and stress-induced senescence are discussed, as well as the potential role of GS1 and GDH in a metabolic safeguard process.
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Affiliation(s)
- Karine Pageau
- INRA Unité de Nutrition Azotée des Plantes, Route de Saint Cyr, F-78 026 Versailles Cedex, France
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Cooke JEK, Weih M. Nitrogen storage and seasonal nitrogen cycling in Populus: bridging molecular physiology and ecophysiology. THE NEW PHYTOLOGIST 2005; 167:19-30. [PMID: 15948826 DOI: 10.1111/j.1469-8137.2005.01451.x] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
While both annual and perennial plants store nitrogen resources during the growing season, seasonal N cycling is a hallmark of the perennial habit. In Populus the vegetative storage proteins BSP, WIN4 and PNI288 all play a role in N storage during active growth, whereas BSP is the major form of reduced N storage during winter dormancy. In this review we explore cellular and molecular events implicated in seasonal N cycling in Populus, as well as environmental cues that modulate both the phenology of seasonal N cycling, and the efficiency and proficiency of autumn N resorption. We highlight recent advances that have been made using Populus genomics resources to address processes germane to seasonal N cycling. Genetic and genetological studies are enabling us to connect our understanding of seasonal N cycling at molecular and cellular levels with that at ecophysiological levels. With the genomics resources and foundational knowledge that are now in place, Populus researchers are poised to build an integrative understanding of seasonal N cycling that spans from genomes to ecosystems.
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Affiliation(s)
- Janice E K Cooke
- Université Laval, Centre de Recherche en Biologie Forestière, Sainte-Foy, Québec G1K 7P4, Canada.
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Masclaux-Daubresse C, Carrayol E, Valadier MH. The two nitrogen mobilisation- and senescence-associated GS1 and GDH genes are controlled by C and N metabolites. PLANTA 2005; 221:580-8. [PMID: 15654637 DOI: 10.1007/s00425-004-1468-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2004] [Accepted: 11/19/2004] [Indexed: 05/22/2023]
Abstract
In tobacco, the two enzymes of nitrogen metabolism, cytosolic glutamine synthetase (GS1; E.C.6.3.1.2) and glutamate dehydrogenase (GDH; E.C.1.4.1.2), are induced during leaf senescence, whereas the chloroplastic glutamine synthetase (GS2; E.C.6.3.1.2) and nitrate reductase (NR; E.C.1.6.1.1) are repressed in the course of ageing. In this report, we showed in discs of fully expanded Nicotiana tabacum L. cv. Xanthi leaves that sucrose (Suc) and amino acids were involved in the regulation of the expression of GS1 and GDH genes. Suc induced the expression of GS1 and repressed that of GDH. Therefore, we concluded that in response to Suc, GS1 behaved as an "early" Senescence Associated Gene (SAG), whereas GDH behaved as a "late" SAG. Moreover, amino acids induced the expression of both genes. Among the amino acids tested as signal molecules, proline (Pro) and glutamate (Glu) were major inducers of GDH and GS1 expression, respectively. Interestingly, an opposite regulation of GS1 and GS2 by Pro and Glu was shown. The contrary effect of Suc on NIA (NR encoding gene) and GDH mRNA accumulation was also emphasized.
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Affiliation(s)
- Céline Masclaux-Daubresse
- Unité de Nutrition Azotée des Plantes, Institut National de la Recherche Agronomique, Route de St-Cyr, 78026 Versailles Cedex, France.
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Cantón FR, Suárez MF, Cánovas FM. Molecular aspects of nitrogen mobilization and recycling in trees. PHOTOSYNTHESIS RESEARCH 2005; 83:265-78. [PMID: 16143856 DOI: 10.1007/s11120-004-9366-9] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2004] [Accepted: 05/03/2004] [Indexed: 05/04/2023]
Abstract
Plants have developed a variety of molecular strategies to use limiting nutrients with a maximum efficiency. N assimilated into biomolecules can be released in the form of ammonium by plant metabolic activities in various physiological processes such as photorespiration, the biosynthesis of phenylpropanoids or the mobilization of stored reserves. Thus, efficient reassimilation mechanisms are required to reincorporate liberated ammonium into metabolism and maintain N plant economy. Although the biochemistry and molecular biology of ammonium recycling in annual herbaceous plants has been previously reported, the recent advances in woody plants need to be reviewed. Moreover, it is important to point out that N recycling is quantitatively massive during some of these metabolic processes in trees, including seed germination, the onset of dormancy and resumption of active growth or the biosynthesis of lignin that takes place during wood formation. Therefore, woody plants constitute an excellent system as a model to study N mobilization and recycling. The aim of this paper is to provide an overview of different physiological processes in woody perennials that challenge the overall plant N economy by releasing important amounts of inorganic N in the form of ammonium.
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Affiliation(s)
- Francisco R Cantón
- Departamento de Biología Molecular y Bioquímica, Instituto Andaluz de Biotecnología, Unidad Asociada UMA-CSIC, Universidad de Málaga, Málaga 29071, Spain
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Tercé-Laforgue T, Mäck G, Hirel B. New insights towards the function of glutamate dehydrogenase revealed during source-sink transition of tobacco (Nicotiana tabacum) plants grown under different nitrogen regimes. PHYSIOLOGIA PLANTARUM 2004; 120:220-228. [PMID: 15032856 DOI: 10.1111/j.0031-9317.2004.0241.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The metabolic, biochemical and molecular events occurring in the different leaf stages along the main axis of tobacco (Nicotiana tabacum) plants grown either on a nitrogen-rich medium, on a medium containing ammonium as sole nitrogen source or on a nitrogen-depleted medium, are presented. This study shows that the highest induction of cytosolic glutamine synthetase (GS1) protein and transcript occurs when nitrogen remobilization is maximal as the result of nitrogen starvation, whereas both glutamate dehydrogenase (GDH) transcript and activity remain at a very low level. In contrast, GDH is highly induced when plants are grown on ammonium as sole nitrogen source, a physiological situation during which leaf protein nitrogen remobilization is limited. It is therefore concluded that GDH does not play a direct role during the process of nitrogen remobilization but is rather induced following a built up of ammonium provided externally or released as the result of protein hydrolysis during natural leaf senescence.
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Affiliation(s)
- Thérèse Tercé-Laforgue
- Unité de Nutrition Azotée des Plantes, INRA, Centre de Versailles, Route de Saint Cyr, F-78026 Versailles Cedex, France
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Husted S, Mattsson M, Möllers C, Wallbraun M, Schjoerring JK. Photorespiratory NH(4)(+) production in leaves of wild-type and glutamine synthetase 2 antisense oilseed rape. PLANT PHYSIOLOGY 2002; 130:989-98. [PMID: 12376662 PMCID: PMC166624 DOI: 10.1104/pp.006759] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2002] [Revised: 05/05/2002] [Accepted: 05/16/2002] [Indexed: 05/18/2023]
Abstract
Exposure of oilseed rape (Brassica napus) plants to increasing leaf temperatures between 15 degrees C and 25 degrees C increased photorespiratory NH(4)(+) production from 0.7 to 3.5 micromol m(-2) s(-1). Despite the 5-fold increase in the rate of NH(4)(+) production, the NH(4)(+) concentration in root and leaf tissue water and xylem sap dropped significantly, whereas that in the leaf apoplastic fluid remained constant. The in vitro activity of glutamine synthetase (GS) in both leaves and roots also increased with temperature and in all cases substantially exceeded the observed rates of photorespiratory NH(4)(+) production. The surplus of GS in oilseed rape plants was confirmed using GS2 antisense plants with 50% to 75% lower in vitro leaf GS activity than in the wild type. Despite the substantial reduction in GS activity, there was no tendency for antisense plants to have higher tissue NH(4)(+) concentrations than wild-type plants and no overall correlation between GS activity and tissue NH(4)(+) concentration was observed. Antisense plants exposed to leaf temperatures increasing from 14 degrees C to 27 degrees C or to a trifold increase in the O(2) to CO(2) ratio did not show any change in steady-state leaf tissue NH(4)(+) concentration or in NH(3) emission to the atmosphere. The antisense plants also had similar leaf tissue concentrations of glutamine, glycine, and serine as the wild type, whereas glutamate increased by 38%. It is concluded that photorespiration does not control tissue or apoplastic levels of NH(4)(+) in oilseed rape leaves and, as a consequence, that photorespiration does not exert a direct control on leaf atmosphere NH(3) fluxes.
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Affiliation(s)
- Søren Husted
- Plant Nutrition Laboratory, The Royal Veterinary and Agricultural University, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Copenhagen, Denmark
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Inokuchi R, Kuma KI, Miyata T, Okada M. Nitrogen-assimilating enzymes in land plants and algae: phylogenic and physiological perspectives. PHYSIOLOGIA PLANTARUM 2002; 116:1-11. [PMID: 12207656 DOI: 10.1034/j.1399-3054.2002.1160101.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
An important biochemical feature of autotrophs, land plants and algae, is their incorporation of inorganic nitrogen, nitrate and ammonium, into the carbon skeleton. Nitrate and ammonium are converted into glutamine and glutamate to produce organic nitrogen compounds, for example proteins and nucleic acids. Ammonium is not only a preferred nitrogen source but also a key metabolite, situated at the junction between carbon metabolism and nitrogen assimilation, because nitrogen compounds can choose an alternative pathway according to the stages of their growth and environmental conditions. The enzymes involved in the reactions are nitrate reductase (EC 1.6.6.1-2), nitrite reductase (EC 1.7.7.1), glutamine synthetase (EC 6.3.1.2), glutamate synthase (EC 1.4.1.13-14, 1.4.7.1), glutamate dehydrogenase (EC 1.4.1.2-4), aspartate aminotransferase (EC 2.6.1.1), asparagine synthase (EC 6.3.5.4), and phosphoenolpyruvate carboxylase (EC 4.1.1.31). Many of these enzymes exist in multiple forms in different subcellular compartments within different organs and tissues, and play sometimes overlapping and sometimes distinctive roles. Here, we summarize the biochemical characteristics and the physiological roles of these enzymes. We also analyse the molecular evolution of glutamine synthetase, glutamate synthase and glutamate dehydrogenase, and discuss the evolutionary relationships of these three enzymes.
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Affiliation(s)
- Ritsuko Inokuchi
- Department of Biomolecular Science, Faculty of Science, Toho University, Chiba 274-8510, Japan Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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Miflin BJ, Habash DZ. The role of glutamine synthetase and glutamate dehydrogenase in nitrogen assimilation and possibilities for improvement in the nitrogen utilization of crops. JOURNAL OF EXPERIMENTAL BOTANY 2002; 53:979-87. [PMID: 11912240 DOI: 10.1093/jexbot/53.370.979] [Citation(s) in RCA: 346] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
This short review outlines the central role of glutamine synthetase (GS) in plant nitrogen metabolism and discusses some possibilities for crop improvement. GS functions as the major assimilatory enzyme for ammonia produced from N fixation, and nitrate or ammonia nutrition. It also reassimilates ammonia released as a result of photorespiration and the breakdown of proteins and nitrogen transport compounds. GS is distributed in different subcellular locations (chloroplast and cytoplasm) and in different tissues and organs. This distribution probably changes as a function of the development of the tissue, for example, GS1 appears to play a key role in leaf senescence. The enzyme is the product of multiple genes with complex promoters that ensure the expression of the genes in an organ- and tissue-specific manner and in response to a number of environmental variables affecting the nutritional status of the cell. GS activity is also regulated post-translationally in a manner that involves 14-3-3 proteins and phosphorylation. GS and plant nitrogen metabolism is best viewed as a complex matrix continually changing during the development cycle of plants. Along with GS, a number of other enzymes play key roles in maintaining the balance of carbon and nitrogen. It is proposed that one of these is glutamate dehydrogenase (GDH). There is considerable evidence for a GDH shunt to return the carbon in amino acids back into reactions of carbon metabolism and the tri-carboxylic acid cycle. Results with transgenic plants containing transferred GS genes suggest that there may be ways in which it is possible to improve the efficiency with which crop plants use nitrogen. Marker-assisted breeding may also bring about such improvements.
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Affiliation(s)
- Ben J Miflin
- Crop Performance and Improvement Division, IACR-Rothamsted, Harpenden, Hertfordshire AL5 2JQ, UK.
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Hörtensteiner S, Feller U. Nitrogen metabolism and remobilization during senescence. JOURNAL OF EXPERIMENTAL BOTANY 2002; 53:927-37. [PMID: 11912235 DOI: 10.1093/jexbot/53.370.927] [Citation(s) in RCA: 318] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Senescence is a highly organized and well-regulated process. As much as 75% of total cellular nitrogen may be located in mesophyll chloroplasts of C(3)-plants. Proteolysis of chloroplast proteins begins in an early phase of senescence and the liberated amino acids can be exported to growing parts of the plant (e.g. maturing fruits). Rubisco and other stromal enzymes can be degraded in isolated chloroplasts, implying the involvement of plastidial peptide hydrolases. Whether or not ATP is required and if stromal proteins are modified (e.g. by reactive oxygen species) prior to their degradation are questions still under debate. Several proteins, in particular cysteine proteases, have been demonstrated to be specifically expressed during senescence. Their contribution to the general degradation of chloroplast proteins is unclear. The accumulation in intact cells of peptide fragments and inhibitor studies suggest that multiple degradation pathways may exist for stromal proteins and that vacuolar endopeptidases might also be involved under certain conditions. The breakdown of chlorophyll-binding proteins associated with the thylakoid membrane is less well investigated. The degradation of these proteins requires the simultaneous catabolism of chlorophylls. The breakdown of chlorophylls has been elucidated during the last decade. Interestingly, nitrogen present in chlorophyll is not exported from senescencing leaves, but remains within the cells in the form of linear tetrapyrrolic catabolites that accumulate in the vacuole. The degradation pathways for chlorophylls and chloroplast proteins are partially interconnected.
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Affiliation(s)
- Stefan Hörtensteiner
- Institute of Plant Sciences, University of Bern, Altenbergrain 21, CH-3013 Bern, Switzerland
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Suárez MF, Avila C, Gallardo F, Cantón FR, García-Gutiérrez A, Claros MG, Cánovas FM. Molecular and enzymatic analysis of ammonium assimilation in woody plants. JOURNAL OF EXPERIMENTAL BOTANY 2002; 53:891-904. [PMID: 11912232 DOI: 10.1093/jexbot/53.370.891] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Ammonium is assimilated into amino acids through the sequential action of glutamine synthetase (GS) and glutamate synthase (GOGAT) enzymes. This metabolic pathway is driven by energy, reducing power and requires the net supply of 2-oxoglutarate that can be provided by the reaction catalysed by isocitrate dehydrogenase (IDH). Most studies on the biochemistry and molecular biology of N-assimilating enzymes have been carried out on annual plant species and the available information on woody models is far more limited. This is in spite of their economic and ecological importance and the fact that nitrogen is a common limiting factor for tree growth. GS, GOGAT and IDH enzymes have been purified from several woody species and their kinetic and molecular properties determined. A number of cDNA clones have also been isolated and characterized. Although the enzymes are remarkably well conserved along the evolutionary scale, major differences have been found in their compartmentation within the cell between angiosperms and conifers, suggesting possible adaptations to specific functional roles. The analysis of the gene expression patterns in a variety of biological situations such as changes in N nutrition, development, biotic or abiotic stresses and senescence, suggest that cytosolic GS plays a central and pivotal role in ammonium assimilation and metabolism in woody plants. The modification of N assimilation efficiency has been recently approached in trees by overexpression of a cytosolic pine GS in poplar. The results obtained, suggest that an increase in cytosolic GS might lead to a global effect on the synthesis of nitrogenous compounds in the leaves, with enhanced vegetative growth of transgenic trees. All these data suggest that manipulation of cytosolic GS may have consequences for plant growth and biomass production.
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Affiliation(s)
- María Fernanda Suárez
- Departamento de Biología Molecular y Bioquímica, Instituto Andaluz de Biotecnología, Unidad Asociada UMA-CSIC, Universidad de Málaga, E29071-Málaga, Spain
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The Biochemistry, Molecular Biology, and Genetic Manipulation of Primary Ammonia Assimilation. ADVANCES IN PHOTOSYNTHESIS AND RESPIRATION 2002. [DOI: 10.1007/0-306-48138-3_6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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Fuentes SI, Allen DJ, Ortiz-Lopez A, Hernández G. Over-expression of cytosolic glutamine synthetase increases photosynthesis and growth at low nitrogen concentrations. JOURNAL OF EXPERIMENTAL BOTANY 2001; 52:1071-81. [PMID: 11432923 DOI: 10.1093/jexbot/52.358.1071] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Nitrogen, which is a major limiting nutrient for plant growth, is assimilated as ammonium by the concerted action of glutamine synthetase (GS) and glutamate synthase (GOGAT). GS catalyses the critical incorporation of inorganic ammonium into the amino acid glutamine. Two types of GS isozymes, located in the cytosol (GS1) and in the chloroplast (GS2) have been identified in plants. Tobacco (Nicotiana tabacum) transformants, over-expressing GS1 driven by the constitutive CaMV 35S promoter were analysed. GS in leaves of GS-5 and GS-8 plants was up-regulated, at the level of RNA and proteins. These transgenic plants had six times higher leaf GS activity than controls. Under optimum nitrogen fertilization conditions there was no effect of GS over-expression on photosynthesis or growth. However, under nitrogen starvation the GS transgenics had c. 70% higher shoot and c. 100% greater root dry weight as well as 50% more leaf area than low nitrogen controls. This was achieved by the maintenance of photosynthesis at rates indistinguishable from plants under high nitrogen, while photosynthesis in control plants was inhibited by 40-50% by nitrogen deprivation. It was demonstrated that manipulation of GS activity has the potential to maintain crop photosynthetic productivity while reducing nitrogen fertilization and the concomitant pollution.
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Affiliation(s)
- S I Fuentes
- Centro de Investigación sobre Fijación de Nitrógeno, UNAM, Apartado Postal 565-A, Cuernavaca, Mor. México
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