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Pagano A, Macovei A, Balestrazzi A. Molecular dynamics of seed priming at the crossroads between basic and applied research. PLANT CELL REPORTS 2023; 42:657-688. [PMID: 36780009 PMCID: PMC9924218 DOI: 10.1007/s00299-023-02988-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 01/20/2023] [Indexed: 06/18/2023]
Abstract
The potential of seed priming is still not fully exploited. Our limited knowledge of the molecular dynamics of seed pre-germinative metabolism is the main hindrance to more effective new-generation techniques. Climate change and other recent global crises are disrupting food security. To cope with the current demand for increased food, feed, and biofuel production, while preserving sustainability, continuous technological innovation should be provided to the agri-food sector. Seed priming, a pre-sowing technique used to increase seed vigor, has become a valuable tool due to its potential to enhance germination and stress resilience under changing environments. Successful priming protocols result from the ability to properly act on the seed pre-germinative metabolism and stimulate events that are crucial for seed quality. However, the technique still requires constant optimization, and researchers are committed to addressing some key open questions to overcome such drawbacks. In this review, an update of the current scientific and technical knowledge related to seed priming is provided. The rehydration-dehydration cycle associated with priming treatments can be described in terms of metabolic pathways that are triggered, modulated, or turned off, depending on the seed physiological stage. Understanding the ways seed priming affects, either positively or negatively, such metabolic pathways and impacts gene expression and protein/metabolite accumulation/depletion represents an essential step toward the identification of novel seed quality hallmarks. The need to expand the basic knowledge on the molecular mechanisms ruling the seed response to priming is underlined along with the strong potential of applied research on primed seeds as a source of seed quality hallmarks. This route will hasten the implementation of seed priming techniques needed to support sustainable agriculture systems.
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Affiliation(s)
- Andrea Pagano
- Department of Biology and Biotechnology 'L. Spallanzani', Via Ferrata 1, 27100, Pavia, Italy
| | - Anca Macovei
- Department of Biology and Biotechnology 'L. Spallanzani', Via Ferrata 1, 27100, Pavia, Italy
- National Biodiversity Future Center (NBFC), 90133, Palermo, Italy
| | - Alma Balestrazzi
- Department of Biology and Biotechnology 'L. Spallanzani', Via Ferrata 1, 27100, Pavia, Italy.
- National Biodiversity Future Center (NBFC), 90133, Palermo, Italy.
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Domergue JB, Abadie C, Limami A, Way D, Tcherkez G. Seed quality and carbon primary metabolism. PLANT, CELL & ENVIRONMENT 2019; 42:2776-2788. [PMID: 31323691 DOI: 10.1111/pce.13618] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 07/05/2019] [Accepted: 07/13/2019] [Indexed: 05/28/2023]
Abstract
Improving seed quality is amongst the most important challenges of contemporary agriculture. In fact, using plant varieties with better germination rates that are more tolerant to stress during seedling establishment may improve crop yield considerably. Therefore, intense efforts are currently being devoted to improve seed quality in many species, mostly using genomics tools. However, despite its considerable importance during seed imbibition and germination processes, primary carbon metabolism in seeds is less studied. Our knowledge of the physiology of seed respiration and energy generation and the impact of these processes on seed performance have made limited progress over the past three decades. In particular, (isotope-assisted) metabolomics of seeds has only been assessed occasionally, and there is limited information on possible quantitative relationships between metabolic fluxes and seed quality. Here, we review the recent literature and provide an overview of potential links between metabolic efficiency, metabolic biomarkers, and seed quality and discuss implications for future research, including a climate change context.
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Affiliation(s)
- Jean-Baptiste Domergue
- IRHS Institut de Recherche en Horticultures et Séances, UMR 1345, INRA, Agrocampus-Ouest, Université d'Angers SFR 4207 QuaSaV, Beaucouzé, 49070, France
| | - Cyril Abadie
- IRHS Institut de Recherche en Horticultures et Séances, UMR 1345, INRA, Agrocampus-Ouest, Université d'Angers SFR 4207 QuaSaV, Beaucouzé, 49070, France
| | - Anis Limami
- IRHS Institut de Recherche en Horticultures et Séances, UMR 1345, INRA, Agrocampus-Ouest, Université d'Angers SFR 4207 QuaSaV, Beaucouzé, 49070, France
| | - Danielle Way
- Department of Biology, University of Western Ontario, London, ON, N6A 5B7, Canada
- Research School of Biology, ANU Joint College of Sciences, Australian National University, Canberra, ACT, 2601, Australia
- Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA
| | - Guillaume Tcherkez
- IRHS Institut de Recherche en Horticultures et Séances, UMR 1345, INRA, Agrocampus-Ouest, Université d'Angers SFR 4207 QuaSaV, Beaucouzé, 49070, France
- Research School of Biology, ANU Joint College of Sciences, Australian National University, Canberra, ACT, 2601, Australia
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Ashihara H, Stasolla C, Fujimura T, Crozier A. Purine salvage in plants. PHYTOCHEMISTRY 2018; 147:89-124. [PMID: 29306799 DOI: 10.1016/j.phytochem.2017.12.008] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 12/10/2017] [Accepted: 12/14/2017] [Indexed: 05/04/2023]
Abstract
Purine bases and nucleosides are produced by turnover of nucleotides and nucleic acids as well as from some cellular metabolic pathways. Adenosine released from the S-adenosyl-L-methionine cycle is linked to many methyltransferase reactions, such as the biosynthesis of caffeine and glycine betaine. Adenine is produced by the methionine cycles, which is related to other biosynthesis pathways, such those for the production of ethylene, nicotianamine and polyamines. These purine compounds are recycled for nucleotide biosynthesis by so-called "salvage pathways". However, the salvage pathways are not merely supplementary routes for nucleotide biosynthesis, but have essential functions in many plant processes. In plants, the major salvage enzymes are adenine phosphoribosyltransferase (EC 2.4.2.7) and adenosine kinase (EC 2.7.1.20). AMP produced by these enzymes is converted to ATP and utilised as an energy source as well as for nucleic acid synthesis. Hypoxanthine, guanine, inosine and guanosine are salvaged to IMP and GMP by hypoxanthine/guanine phosphoribosyltransferase (EC 2.4.2.8) and inosine/guanosine kinase (EC 2.7.1.73). In contrast to de novo purine nucleotide biosynthesis, synthesis by the salvage pathways is extremely favourable, energetically, for cells. In addition, operation of the salvage pathway reduces the intracellular levels of purine bases and nucleosides which inhibit other metabolic reactions. The purine salvage enzymes also catalyse the respective formation of cytokinin ribotides, from cytokinin bases, and cytokinin ribosides. Since cytokinin bases are the active form of cytokinin hormones, these enzymes act to maintain homeostasis of cellular cytokinin bioactivity. This article summarises current knowledge of purine salvage pathways and their possible function in plants and purine salvage activities associated with various physiological phenomena are reviewed.
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Affiliation(s)
- Hiroshi Ashihara
- Department of Biology, Ochanomizu University, Bunkyo-ku, Tokyo, 112-8610, Japan.
| | - Claudio Stasolla
- Department of Plant Science, University of Manitoba, Winnipeg, R3T 2N2, Canada
| | - Tatsuhito Fujimura
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, 305-8572, Japan
| | - Alan Crozier
- Department of Nutrition, University of California, Davis, CA, 95616-5270, USA
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Führs H, Behrens C, Gallien S, Heintz D, Van Dorsselaer A, Braun HP, Horst WJ. Physiological and proteomic characterization of manganese sensitivity and tolerance in rice (Oryza sativa) in comparison with barley (Hordeum vulgare). ANNALS OF BOTANY 2010; 105:1129-40. [PMID: 20237113 PMCID: PMC2887067 DOI: 10.1093/aob/mcq046] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Revised: 01/04/2010] [Accepted: 01/18/2010] [Indexed: 05/18/2023]
Abstract
BACKGROUND AND AIMS Research on manganese (Mn) toxicity and tolerance indicates that Mn toxicity develops apoplastically through increased peroxidase activities mediated by phenolics and Mn, and Mn tolerance could be conferred by sequestration of Mn in inert cell compartments. This comparative study focuses on Mn-sensitive barley (Hordeum vulgare) and Mn-tolerant rice (Oryza sativa) as model organisms to unravel the mechanisms of Mn toxicity and/or tolerance in monocots. METHODS Bulk leaf Mn concentrations as well as peroxidase activities and protein concentrations were analysed in apoplastic washing fluid (AWF) in both species. In rice, Mn distribution between leaf compartments and the leaf proteome using 2D isoelectric focusing IEF/SDS-PAGE and 2D Blue native BN/SDS-PAGE was studied. KEY RESULTS The Mn sensitivity of barley was confirmed since the formation of brown spots on older leaves was induced by low bulk leaf and AWF Mn concentrations and exhibited strongly enhanced H2O2-producing and consuming peroxidase activities. In contrast, by a factor of 50, higher Mn concentrations did not produce Mn toxicity symptoms on older leaves in rice. Peroxidase activities, lower by a factor of about 100 in the rice leaf AWF compared with barley, support the view of a central role for these peroxidases in the apoplastic expression of Mn toxicity. The high Mn tolerance of old rice leaves could be related to a high Mn binding capacity of the cell walls. Proteomic studies suggest that the lower Mn tolerance of young rice leaves could be related to Mn excess-induced displacement of Mg and Fe from essential metabolic functions. CONCLUSIONS The results provide evidence that Mn toxicity in barley involves apoplastic lesions mediated by peroxidases. The high Mn tolerance of old leaves of rice involves a high Mn binding capacity of the cell walls, whereas Mn toxicity in less Mn-tolerant young leaves is related to Mn-induced Mg and Fe deficiencies.
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Affiliation(s)
- Hendrik Führs
- Institute for Plant Nutrition, Faculty of Natural Sciences, Leibniz University Hannover, Herrenhäuser Str. 2, D-30419 Hannover, Germany
| | - Christof Behrens
- Institute for Plant Genetics, Faculty of Natural Sciences, Leibniz University Hannover, Herrenhäuser Str. 2, D-30419 Hannover, Germany
| | - Sébastien Gallien
- Laboratoire de Spectrométrie de Masse Bio-organique, IPHC-DSA, Université de Strasbourg, CNRS, UMR7178, 25 rue Becquerel, 67087 Strasbourg, France
| | - Dimitri Heintz
- Institut de Biologie Mooléculaire des Plantes (IBMP), 28 rue Goethe, CNRS-UPR2357, Université de Strasbourg, 67083 Strasbourg, France
| | - Alain Van Dorsselaer
- Laboratoire de Spectrométrie de Masse Bio-organique, IPHC-DSA, Université de Strasbourg, CNRS, UMR7178, 25 rue Becquerel, 67087 Strasbourg, France
| | - Hans-Peter Braun
- Institute for Plant Genetics, Faculty of Natural Sciences, Leibniz University Hannover, Herrenhäuser Str. 2, D-30419 Hannover, Germany
| | - Walter J. Horst
- Institute for Plant Nutrition, Faculty of Natural Sciences, Leibniz University Hannover, Herrenhäuser Str. 2, D-30419 Hannover, Germany
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Levy HR. Glucose-6-phosphate dehydrogenases. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2006; 48:97-192. [PMID: 367106 DOI: 10.1002/9780470122938.ch3] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Stasolla C, Katahira R, Thorpe TA, Ashihara H. Purine and pyrimidine nucleotide metabolism in higher plants. JOURNAL OF PLANT PHYSIOLOGY 2003; 160:1271-95. [PMID: 14658380 DOI: 10.1078/0176-1617-01169] [Citation(s) in RCA: 201] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Purine and pyrimidine nucleotides participate in many biochemical processes in plants. They are building blocks for nucleic acid synthesis, an energy source, precursors for the synthesis of primary products, such as sucrose, polysaccharides, phospholipids, as well as secondary products. Therefore, biosynthesis and metabolism of nucleotides are of fundamental importance in the growth and development of plants. Nucleotides are synthesized both from amino acids and other small molecules via de novo pathways, and from preformed nucleobases and nucleosides by salvage pathways. In this article the biosynthesis, interconversion and degradation of purine and pyrimidine nucleotides in higher plants are reviewed. This description is followed by an examination of physiological aspects of nucleotide metabolism in various areas of growth and organized development in plants, including embryo maturation and germination, in vitro organogenesis, storage organ development and sprouting, leaf senescence, and cultured plant cells. The effects of environmental factors on nucleotide metabolism are also described. This review ends with a brief discussion of molecular studies on nucleotide synthesis and metabolism.
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Affiliation(s)
- Claudio Stasolla
- Department of Plant Science, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada
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7
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Moffatt BA, Wang L, Allen MS, Stevens YY, Qin W, Snider J, von Schwartzenberg K. Adenosine kinase of Arabidopsis. Kinetic properties and gene expression. PLANT PHYSIOLOGY 2000; 124:1775-85. [PMID: 11115893 PMCID: PMC59874 DOI: 10.1104/pp.124.4.1775] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2000] [Revised: 05/22/2000] [Accepted: 07/18/2000] [Indexed: 05/17/2023]
Abstract
To assess the functional significance of adenosine salvage in plants, the cDNAs and genes encoding two isoforms of adenosine kinase (ADK) were isolated from Arabidopsis. The ADK1- and ADK2-coding sequences are very similar, sharing 92% and 89% amino acid and nucleotide identity, respectively. Each cDNA was overexpressed in Escherichia coli, and the catalytic activity of each isoform was determined. Both ADKs had similar catalytic properties with a K(m) and V(max)/K(m) for adenosine of 0.3 to 0.5 microM and 5.4 to 22 L min(-1) mg(-1) protein, respectively. The K(m) and V(max)/K(m) for the cytokinin riboside N(6)(isopentenyl) adenosine are 3 to 5 microM and 0.021 to 0.14 L min(-1) mg(-1) protein, respectively, suggesting that adenosine is the preferred substrate for both ADK isoforms. In Arabidopsis plants, both ADK genes are expressed constitutively, with the highest steady-state mRNA levels being found in stem and root. ADK1 transcript levels were generally higher than those of ADK2. ADK enzyme activity reflected relative ADK protein levels seen in immunoblots for leaves, flowers, and stems but only poorly so for roots, siliques, and dry seeds. The catalytic properties, tissue accumulation, and expression levels of these ADKs suggest that they play a key metabolic role in the salvage synthesis of adenylates and methyl recycling in Arabidopsis. They may also contribute to cytokinin interconversion.
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MESH Headings
- Adenosine/metabolism
- Adenosine Kinase/genetics
- Adenosine Kinase/metabolism
- Arabidopsis/enzymology
- Arabidopsis/genetics
- Blotting, Northern
- Cytokinins/metabolism
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- DNA, Complementary/isolation & purification
- DNA, Plant/chemistry
- DNA, Plant/genetics
- DNA, Plant/isolation & purification
- Gene Expression Regulation, Enzymologic
- Gene Expression Regulation, Plant
- Genes, Plant/genetics
- Isoenzymes/genetics
- Isoenzymes/metabolism
- Kinetics
- Molecular Sequence Data
- Phylogeny
- Promoter Regions, Genetic
- RNA, Plant/genetics
- RNA, Plant/metabolism
- Sequence Analysis, DNA
- Substrate Specificity
- Tissue Distribution
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Affiliation(s)
- B A Moffatt
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1.
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8
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Guranowski A, Starzyńska E, Rataj-Guranowska M, Günther Sillero MA. Purification of apyrase from yellow lupin cotyledons after extraction with perchloric acid. Protein Expr Purif 1991; 2:235-9. [PMID: 1668272 DOI: 10.1016/1046-5928(91)90078-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Neutralized 1 M perchloric acid (PCA) extracts of yellow lupin (Lupinus luteus) seedling cotyledons contain considerable amounts of apyrase (EC 3.6.1.5). Investigators who use PCA extraction for the estimation of nucleotide levels, particularly in plant tissues, should be aware of this danger. Only when the material is treated with 1.8-2 M PCA are the extracts obtained free of apyrase activity. Chromatography of neutralized 1 M extracts obtained from 7-day-old seedling cotyledons on DEAE-Sephacel and Sephadex G-100 yields almost homogeneous apyrase that shows a band of M(r) 51,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels. The molecular weight of the native enzyme is also about 51,000. The apyrase preparation is free of nonspecific phosphatases, nucleotidases, and adenosine nucleosidase, as well as dinucleoside polyphosphate-degrading enzymes. The apyrase exhibits a broad pH optimum between 6 and 8. Mg2+ and Ca2+ are required for maximum activity; Zn2+ and Mn2+ are less effective and Co2+, Ni2+, and Cd2+ are without effect. The Km values for ATP and ADP are about 20 microM. All common 5'-nucleoside tri- and diphosphates as well as adenosine 5'-tetraphosphate are substrates.
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Affiliation(s)
- A Guranowski
- Katedra Biochemii, Akademia Rolnicza, Poznań, Poland
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9
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Schuller KA, Day DA, Gibson AH, Gresshoff PM. Enzymes of ammonia assimilation and ureide biosynthesis in soybean nodules: effect of nitrate. PLANT PHYSIOLOGY 1986; 80:646-50. [PMID: 16664678 PMCID: PMC1075176 DOI: 10.1104/pp.80.3.646] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The effect of nitrate on N(2) fixation and the assimilation of fixed N(2) in legume nodules was investigated by supplying nitrate to well established soybean (Glycine max L. Merr. cv Bragg)-Rhizobium japonicum (strain 3I1b110) symbioses. Three different techniques, acetylene reduction, (15)N(2) fixation and relative abundance of ureides ([ureides/(ureides + nitrate + alpha-amino nitrogen)] x 100) in xylem exudate, gave similar results for the effect of nitrate on N(2) fixation by nodulated roots. After 2 days of treatment with 10 millimolar nitrate, acetylene reduction by nodulated roots was inhibited by 48% but there was no effect on either acetylene reduction by isolated bacteroids or in vitro activity of nodule cytoplasmic glutamine synthetase, glutamine oxoglutarate aminotransferase, xanthine dehydrogenase, uricase, or allantoinase. After 7 days, acetylene reduction by isolated bacteroids was almost completely inhibited but, except for glutamine oxoglutarate aminotransferase, there was still no effect on the nodule cytoplasmic enzymes. It was concluded that, when nitrate is supplied to an established symbiosis, inhibition of nodulated root N(2) fixation precedes the loss of the potential of bacteroids to fix N(2). This in turn precedes the loss of the potential of nodules to assimilate fixed N(2).
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Affiliation(s)
- K A Schuller
- Botany Department, Australian National University, G.P.O. Box 4, Canberra, A.C.T. 2601, Australia
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Polayes DA, Schubert KR. Purine synthesis and catabolism in soybean seedlings : the biogenesis of ureides. PLANT PHYSIOLOGY 1984; 75:1104-10. [PMID: 16663743 PMCID: PMC1067061 DOI: 10.1104/pp.75.4.1104] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The ureides, allantoin and allantoic acid, are the major nitrogenous substances transported within the xylem of N(2)-fixing soybeans (Glycine max L. Merr. cv Amsoy 71). The ureides accumulated in the cotyledons, roots and shoots of soybean seedlings inoculated with Rhizobium or grown in the presence of 10 millimolar nitrate. The patterns of activity for uricase and allantoinase, enzymes involved in ureide synthesis, were positively correlated with the accumulation of ureides in the roots and cotyledons. Allopurinol and azaserine inhibited ureide production in 3-day-old cotyledons while no inhibition was observed in the roots. Incubation of 4-day-old seedlings with [(14)C]serine indicated that in the cotyledons ureides arose via de novo synthesis of purines. The source of ureides in both 3- and 4-day-old roots was probably the cotyledons. The inhibition of ureide accumulation by allopurinol but not azaserine in 8-day-old cotyledons suggested that ureides in these older cotyledons arose via nucleotide breakdown. Incubation of 8-day-old plants with [(14)C]serine suggested that the roots had acquired the capability to synthesize ureides via de novo synthesis of purines. These data indicate that both de novo purine synthesis and nucleotide breakdown are involved in the production of ureides in young soybean seedlings.
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Affiliation(s)
- D A Polayes
- Department of Biology, Washington University, St. Louis, Missouri 63130
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11
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Srivastava D, Anderson L. Isolation and characterization of light- and dithiothreitol-modulatable glucose-6-phosphate dehydrogenase from pea chloroplasts. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1983. [DOI: 10.1016/0005-2728(83)90095-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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12
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Hirose F, Ashihara H. Adenine Phosphoribosyltransferase of Catharanthus roseus Cells: Purification, Properties and Regulation. ACTA ACUST UNITED AC 1983. [DOI: 10.1016/s0044-328x(83)80160-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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13
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Apelbaum A, Wang SY, Burgoon AC, Baker JE, Lieberman M. Inhibition of the Conversion of 1-Aminocyclopropane-1-carboxylic Acid to Ethylene by Structural Analogs, Inhibitors of Electron Transfer, Uncouplers of Oxidative Phosphorylation, and Free Radical Scavengers. PLANT PHYSIOLOGY 1981; 67:74-9. [PMID: 16661637 PMCID: PMC425624 DOI: 10.1104/pp.67.1.74] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Cyclopropane carboxylic acid (CCA) at 1 to 5 millimolar, unlike related cyclopropane ring analogs of 1-aminocyclopropane-1-carboxylic acid (ACC) which were virtually ineffective, inhibited C(2)H(4) production, and this inhibition was nullified by ACC. Inhibition by CCA is not competitive with ACC since there is a decline, rather than an increase, in native endogenous ACC in the presence of CCA. Similarly, short-chain organic acids from acetic to butyric acid and alpha-aminoisobutyric acid inhibited C(2)H(4) production at 1 to 5 millimolar and lowered endogenous ACC levels. These inhibitions, like that of CCA, were overcome with ACC. Inhibitors of electron transfer and oxidative phosphorylation effectively inhibited ACC conversion to C(2)H(4) in pea and apple tissues. The most potent inhibitors were 2,4-dinitrophenol (DNP) and carbonyl cyanide m-chlorophenylhydrazone (CCCP) which virtually eliminated ACC-stimulated C(2)H(4) production in both tissues. Still other inhibitors of the conversion of ACC to C(2)H(4) were putative free radical scavengers which reduced chemiluminescence in the free radical-activated luminol reaction. These inhibitor studies suggest the involvement of a free radical in the reaction sequence which converts ACC to C(2)H(4). Additionally, the potent inhibition of this reaction by uncouplers of oxidative phosphorylation (DNP and CCCP) suggest the involvement of ATP or the necessity for an intact membrane for C(2)H(4) production from ACC. In the latter case, CCCP may be acting as a proton ionophore to destroy the membrane integrity necessary for C(2)H(4) production.
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Affiliation(s)
- A Apelbaum
- Postharvest Physiology Laboratory, Beltsville Agricultural Research Center (W), Beltsville, Maryland 20705
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14
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Aspart L, Cooke R, Michaux-Ferriere N, Delseny M. Ribosomal RNA synthesis in imbibing radish (Raphanus sativus) embryo axes : A biochemical and cytological study. PLANTA 1980; 148:17-23. [PMID: 24311260 DOI: 10.1007/bf00385436] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/1979] [Accepted: 09/21/1979] [Indexed: 06/02/2023]
Abstract
The first hours of seed germination are characterized by an increase in the rate of RNA synthesis. Although this change is most easily accounted for by changes in the ribonucleotide pool sizes, we investigated two other aspects of rRNA synthesis which are likely to contribute to the phenomenon. Using isolated radish embryo axes, we demonstrate that processing of rRNA gene transcripts is much slower during early germination than during the growth of the seedling. We also provide evidence that rRNA gene expression is sequentially reactivated in different tissues, starting in the provascular tissue and apex cells and only later in the cortical cells of the rootlet.
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Affiliation(s)
- L Aspart
- Laboratoire de Physiologie Végétale, ERA n 226 du CNRS, Centre Universitaire de Perpignan, Avenue de Villeneuve, F-66025, Perpignan-Cedex, France
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15
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Barankiewicz J, Paszkowski J. Purine metabolism in mesophyll protoplasts of tobacco (Nicotiana tabacum) leaves. Biochem J 1980; 186:343-50. [PMID: 6154458 PMCID: PMC1161536 DOI: 10.1042/bj1860343] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The overall metabolism of purines was studied in tobacco (Nicotiana tabacum) mesophyll protoplasts. Metabolic pathways were studied by measuring the conversion of radioactive adenine, adenosine, hypoxanthine and guanine into purine ribonucleotides, ribonucleosides, bases and nucleic acid constituents. Adenine was extensively deaminated to hypoxanthine, whereupon it was also converted into AMP and incorporated into nucleic acids. Adenosine was mainly hydrolysed to adenine. Inosinate formed from hypoxanthine was converted into AMP and GMP, which were then catabolized to adenine and guanosine respectively. Guanine was mainly deaminated to xanthine and also incorporated into nucleic acids via GTP. Increased RNA synthesis in the protoplasts resulted in enhanced incorporation of adenine and guanine, but not of hypoxanthine and adenosine, into the nucleic acid fraction. The overall pattern of purine-nucleotide metabolic pathways in protoplasts of tobacco leaf mesophyll is proposed.
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16
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Mattoo AK, Anderson JD, Chalutz E, Lieberman M. Influence of enol ether amino acids, inhibitors of ethylene biosynthesis, on aminoacyl transfer RNA synthetases and protein synthesis. PLANT PHYSIOLOGY 1979; 64:289-92. [PMID: 16660951 PMCID: PMC543073 DOI: 10.1104/pp.64.2.289] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The analogs of rhizobitoxine, aminoethoxyvinylglycine (AVG) (l-2-amino-4-2'-aminoethoxy-trans-3 butenoic acid) and methoxyvinylglycine (MVG) (l-2-amino-4-methoxy-trans-3-butenoic acid), that are potent inhibitors of ethylene biosynthesis at 0.1 millimolar also inhibited protein synthesis and charging of tRNA especially at 1 millimolar and higher concentrations. The saturated analog of MVG inhibited ethylene synthesis while the saturated analog of AVG did not. Both saturated AVG and MVG inhibit methionyl- and leucyl-amino acyl-tRNA synthetase. Because of the inhibition of amino acid metabolism in plant tissues by these rhizobitoxine analogs caution is advised in interpreting the results obtained with concentrations of compounds above 0.1 millimolar.
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Affiliation(s)
- A K Mattoo
- United States Department of Agriculture, Science and Education Administration, Agricultural Research, AMRI; Post Harvest Plant Physiology Laboratory, Beltsville, Maryland 20705
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17
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Mattoo AK, Chalutz E, Anderson JD, Lieberman M. Characterization of the Phosphate-mediated Control of Ethylene Production by Penicillium digitatum. PLANT PHYSIOLOGY 1979; 64:55-60. [PMID: 16660914 PMCID: PMC543023 DOI: 10.1104/pp.64.1.55] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Characterization of the phosphate effect on ethylene production by Penicillium digitatum is reported. A low level of phosphate (0.001 millimolar) was about 200 to 500 times as effective as a high phosphate level (100 millimolar) in stimulating ethylene production and the stimulation was readily reversed by addition of phosphate. This phosphate effect did not operate in static cultures. The precursor of ethylene in the stimulated low phosphate system was glutamate but not alpha-ketoglutarate, which is a precursor in static systems. Actinomycin D and cycloheximide effectively inhibited the low phosphate/high ethylene-producing system. Alkaline phosphatase and protein kinase activities were higher in low than in high phosphate systems. We suggest that phosphate level regulates ethylene production by P. digitatum and that the regulation involves a phosphorylation or dephosphorylation reaction of some enzyme system associated with ethylene production. Phosphate-mediated control of ethylene production may also involve the transcriptional and translational machinery of the fungal cell. P. digitatum apparently can produce widely different levels of ethylene by different pathways, depending on culture conditions under which it is grown.
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Affiliation(s)
- A K Mattoo
- Post Harvest Plant Physiology Laboratory, Beltsville Agricultural Research Center (W), Beltsville, Maryland 20705
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18
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Anderson JD. Purine nucleotide metabolism of germinating soybean embryonic axes. PLANT PHYSIOLOGY 1979; 63:100-4. [PMID: 16660656 PMCID: PMC542773 DOI: 10.1104/pp.63.1.100] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Isolated soybean (Glycine max L. cv. Kent) embyronic axes metabolized [(14)C]glycine to ATP within the 1 hour of imbibition. Radioactivity was not detected in GTP until the 3rd hour. Throughout most of the first 24 hours of germination about 10 to 26 times as much label from [(14)C]glycine appears in ATP as GTP. About five times as much [(14)C]hypoxanthine and [(14)C]inosine was converted into GTP as into ATP in embryonic axes. Two independent pools of IMP appear to be used in purine nucleotide synthesis of soybean axes.
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Affiliation(s)
- J D Anderson
- Post-Harvest Plant Physiology Laboratory, Agricultural Marketing Research Institute, Beltsville Agricultural Research Center, Science and Education Administration, SEA, United States Department of Agriculture, Beltsville, Maryland 20705
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19
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Parrish DJ, Leopold AC. On the mechanism of aging in soybean seeds. PLANT PHYSIOLOGY 1978; 61:365-8. [PMID: 16660294 PMCID: PMC1091869 DOI: 10.1104/pp.61.3.365] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Changes in seeds of soybeans (Glycine max [L.] Merr. var. Wayne) which occur during accelerated aging (41 C, 100% relative humidity) showed subsequent loss of vigor, a decline in early respiratory activity, increased leakage of electrolytes, losses of as much as 10% dry weight from imbibing cotyledons, and a decrease in the swelling response of the imbibing system (seed plus H(2)O). Each of these changes with aging is interpreted as resulting from deteriorative changes in membranes.
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Affiliation(s)
- D J Parrish
- Department of Agronomy, University of Nebraska, Lincoln, Nebraska 68583
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20
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Anderson JD. Responses of adenine nucleotides in germinating soybean embryonic axes to exogenously applied adenine and adenosine. PLANT PHYSIOLOGY 1977; 60:689-92. [PMID: 16660165 PMCID: PMC542695 DOI: 10.1104/pp.60.5.689] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The ATP content of soybean (Glycine max [L.] Merr. cv. Kent) axes incubated for 3 hours in 1 mm solutions of adenine and adenosine increased over 100% and 75%, respectively, over axes incubated in water. The increase in ATP was primarily due to the conversion of these purines to nucleotides via the nucleotide salvage pathway. The ATP formed was in a metabolically active pool because label from adenine was incorporated into acid-insoluble material. Adenine also increased the levels of GTP, UTP, and CTP, but not to the extent of the ATP level.
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Affiliation(s)
- J D Anderson
- Post Harvest Plant Physiology Laboratory, Agricultural Marketing Research Institute, Beltsville Agricultural Research Center, ARS, Beltsville, Maryland 20705
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