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Aconitase: To Be or not to Be Inside Plant Glyoxysomes, That Is the Question. BIOLOGY 2020; 9:biology9070162. [PMID: 32664680 PMCID: PMC7407140 DOI: 10.3390/biology9070162] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 07/08/2020] [Accepted: 07/10/2020] [Indexed: 12/26/2022]
Abstract
After the discovery in 1967 of plant glyoxysomes, aconitase, one the five enzymes involved in the glyoxylate cycle, was thought to be present in the organelles, and although this was found not to be the case around 25 years ago, it is still suggested in some textbooks and recent scientific articles. Genetic research (including the study of mutants and transcriptomic analysis) is becoming increasingly important in plant biology, so metabolic pathways must be presented correctly to avoid misinterpretation and the dissemination of bad science. The focus of our study is therefore aconitase, from its first localization inside the glyoxysomes to its relocation. We also examine data concerning the role of the enzyme malate dehydrogenase in the glyoxylate cycle and data of the expression of aconitase genes in Arabidopsis and other selected higher plants. We then propose a new model concerning the interaction between glyoxysomes, mitochondria and cytosol in cotyledons or endosperm during the germination of oil-rich seeds.
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Lama K, Peer R, Shlizerman L, Meir S, Doron-Faigenboim A, Sadka A, Aharoni A, Flaishman MA. Tissue-specific organic acid metabolism in reproductive and non-reproductive parts of the fig fruit is partially induced by pollination. PHYSIOLOGIA PLANTARUM 2020; 168:133-147. [PMID: 30740711 DOI: 10.1111/ppl.12941] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 01/30/2019] [Accepted: 02/04/2019] [Indexed: 06/09/2023]
Abstract
Organic acids are important components of overall fruit quality through flavor, taste, nutritional and medicinal values. Pollinated fig (Ficus carica L.) fruit quality is enhanced by increased acidity. We quantified the major organic acids and characterized the expression pattern of organic acid metabolic pathway-related genes in the reproductive part - inflorescence and non-reproductive part - receptacle of parthenocarpic and pollinated fig fruit during ripening. Essentially, pollinated fruit contains seeds in the inflorescence, as opposed to no seeds in the parthenocarpic inflorescence. The major organic acids - citrate and malate - were found in relatively high quantities in the inflorescence compared to the receptacle of both parthenocarpic and pollinated fig fruit. Notably, pollination increased citric acid content significantly in both inflorescence and receptacle. Genes related to the phosphoenolpyruvate carboxylase (PEPC) cycle, tricarboxylic acid cycle, citrate catabolism and glyoxylate cycle were identified in fig fruit. Expression levels of most of these genes were higher in inflorescences than in receptacles. In particular, FcPEPC and FcFUM (encoding fumarase) had significantly higher expression in the inflorescence of pollinated fruit. Most importantly, expression of the glyoxylate cycle genes FcMLS and FcICL (encoding malate synthase and isocitrate lyase, respectively) was induced to strikingly high levels in the inflorescence by pollination, and their expression level was highly positively correlated with the contents of all organic acids. Therefore, the glyoxylate cycle may be responsible for altering the accumulation of organic acids to upgrade the fruit taste during ripening, especially in the pollinated, seeded inflorescence.
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Affiliation(s)
- Kumar Lama
- Institute of Plant Sciences, Agricultural Research Organization, Bet Dagan 50250, Israel
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel
| | - Reut Peer
- Institute of Plant Sciences, Agricultural Research Organization, Bet Dagan 50250, Israel
| | - Lyudmila Shlizerman
- Institute of Plant Sciences, Agricultural Research Organization, Bet Dagan 50250, Israel
| | - Sagit Meir
- Department of Plant and Environmental Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Adi Doron-Faigenboim
- Institute of Plant Sciences, Agricultural Research Organization, Bet Dagan 50250, Israel
| | - Avi Sadka
- Institute of Plant Sciences, Agricultural Research Organization, Bet Dagan 50250, Israel
| | - Asaph Aharoni
- Department of Plant and Environmental Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Moshe A Flaishman
- Institute of Plant Sciences, Agricultural Research Organization, Bet Dagan 50250, Israel
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Yuenyong W, Sirikantaramas S, Qu LJ, Buaboocha T. Isocitrate lyase plays important roles in plant salt tolerance. BMC PLANT BIOLOGY 2019; 19:472. [PMID: 31694539 PMCID: PMC6833277 DOI: 10.1186/s12870-019-2086-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 10/20/2019] [Indexed: 05/27/2023]
Abstract
BACKGROUND Isocitrate lyase (ICL) is a key enzyme in the glyoxylate cycle. In a previous study in rice, the expression of the ICL-encoding gene (OsICL) was highly induced by salt stress and its expression was enhanced in transgenic rice lines overexpressing OsCam1-1, a calmodulin (CaM)-encoding gene. CaM has been implicated in salt tolerance mechanisms in plants; however, the cellular mechanisms mediated by CaM are not clearly understood. In this study, the role of OsICL in plant salt tolerance mechanisms and the possible involvement of CaM were investigated using transgenic plants expressing OsICL or OsCam1-1. RESULTS OsICL was highly expressed in senesced leaf and significantly induced by salt stress in three OsCam1-1 overexpressing transgenic rice lines as well as in wild type (WT). In WT young leaf, although OsICL expression was not affected by salt stress, all three transgenic lines exhibited highly induced expression levels. In Arabidopsis, salt stress had negative effects on germination and seedling growth of the AtICL knockout mutant (Aticl mutant). To examine the roles of OsICL we generated the following transgenic Arabidopsis lines: the Aticl mutant expressing OsICL driven by the native AtICL promoter, the Aticl mutant overexpressing OsICL driven by the 35SCaMV promoter, and WT overexpressing OsICL driven by the 35SCaMV promoter. Under salt stress, the germination rate and seedling fresh and dry weights of the OsICL-expressing lines were higher than those of the Aticl mutant, and the two lines with the icl mutant background were similar to the WT. The Fv/Fm and temperature of rosette leaves in the OsICL-expressing lines were less affected by salt stress than they were in the Aticl mutant. Finally, glucose and fructose contents of the Aticl mutant under salt stress were highest, whereas those of OsICL-expressing lines were similar to or lower than those of the WT. CONCLUSIONS OsICL, a salt-responsive gene, was characterized in the transgenic Arabidopsis lines, revealing that OsICL expression could revert the salt sensitivity phenotypes of the Aticl knockout mutant. This work provides novel evidence that supports the role of ICL in plant salt tolerance through the glyoxylate cycle and the possible involvement of OsCam1-1 in regulating its transcription.
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Affiliation(s)
- Worawat Yuenyong
- Molecular Crop Research Unit, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok, 10330 Thailand
| | - Supaart Sirikantaramas
- Molecular Crop Research Unit, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok, 10330 Thailand
- Omics Sciences and Bioinformatics Center, Faculty of Science, Chulalongkorn University, Bangkok, 10330 Thailand
| | - Li-Jia Qu
- State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences at College of Life Sciences, Peking University, Beijing, 100871 China
- The National Plant Gene Research Center (Beijing), Beijing, 100101 China
| | - Teerapong Buaboocha
- Molecular Crop Research Unit, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok, 10330 Thailand
- Omics Sciences and Bioinformatics Center, Faculty of Science, Chulalongkorn University, Bangkok, 10330 Thailand
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Balic I, Vizoso P, Nilo-Poyanco R, Sanhueza D, Olmedo P, Sepúlveda P, Arriagada C, Defilippi BG, Meneses C, Campos-Vargas R. Transcriptome analysis during ripening of table grape berry cv. Thompson Seedless. PLoS One 2018; 13:e0190087. [PMID: 29320527 PMCID: PMC5761854 DOI: 10.1371/journal.pone.0190087] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 12/07/2017] [Indexed: 11/18/2022] Open
Abstract
Ripening is one of the key processes associated with the development of major organoleptic characteristics of the fruit. This process has been extensively characterized in climacteric fruit, in contrast with non-climacteric fruit such as grape, where the process is less understood. With the aim of studying changes in gene expression during ripening of non-climacteric fruit, an Illumina based RNA-Seq transcriptome analysis was performed on four developmental stages, between veraison and harvest, on table grapes berries cv Thompson Seedless. Functional analysis showed a transcriptional increase in genes related with degradation processes of chlorophyll, lipids, macromolecules recycling and nucleosomes organization; accompanied by a decrease in genes related with chloroplasts integrity and amino acid synthesis pathways. It was possible to identify several processes described during leaf senescence, particularly close to harvest. Before this point, the results suggest a high transcriptional activity associated with the regulation of gene expression, cytoskeletal organization and cell wall metabolism, which can be related to growth of berries and firmness loss characteristic to this stage of development. This high metabolic activity could be associated with an increase in the transcription of genes related with glycolysis and respiration, unexpected for a non-climacteric fruit ripening.
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Affiliation(s)
- Iván Balic
- Universidad Andrés Bello, Facultad Ciencias Biológicas, Centro de Biotecnología Vegetal, Santiago, Chile
- Universidad de Los Lagos, Departamento de Acuicultura y Recursos Agroalimentarios, Osorno, Chile
| | - Paula Vizoso
- Center of Plant Propagation and Conservation (CEPROVEG), Faculty of Sciences, Universidad Mayor, Santiago, Chile
| | | | - Dayan Sanhueza
- Universidad Andrés Bello, Facultad Ciencias Biológicas, Centro de Biotecnología Vegetal, Santiago, Chile
| | - Patricio Olmedo
- Universidad Andrés Bello, Facultad Ciencias Biológicas, Centro de Biotecnología Vegetal, Santiago, Chile
| | - Pablo Sepúlveda
- Universidad Andrés Bello, Facultad Ciencias Biológicas, Centro de Biotecnología Vegetal, Santiago, Chile
| | - Cesar Arriagada
- Laboratorio Biorremediación, Departamento de Ciencias Forestales, Facultad de Ciencias Agropecuarias y Forestales, Universidad de La Frontera, Temuco, Chile
| | - Bruno G. Defilippi
- Instituto de Investigaciones Agropecuarias, INIA La Platina, Santiago, Chile
| | - Claudio Meneses
- Universidad Andrés Bello, Facultad Ciencias Biológicas, Centro de Biotecnología Vegetal, Santiago, Chile
- FONDAP Center for Genome Regulation, Santiago, Chile
| | - Reinaldo Campos-Vargas
- Universidad Andrés Bello, Facultad Ciencias Biológicas, Centro de Biotecnología Vegetal, Santiago, Chile
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Gründel M, Knoop H, Steuer R. Activity and functional properties of the isocitrate lyase in the cyanobacterium Cyanothece sp. PCC 7424. MICROBIOLOGY-SGM 2017; 163:731-744. [PMID: 28516845 DOI: 10.1099/mic.0.000459] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Cyanobacteria are ubiquitous photoautotrophs that assimilate atmospheric CO2 as their main source of carbon. Several cyanobacteria are known to be facultative heterotrophs that are able to grow on diverse carbon sources. For selected strains, assimilation of organic acids and mixotrophic growth on acetate has been reported for decades. However, evidence for the existence of a functional glyoxylate shunt in cyanobacteria has long been contradictory and unclear. Genes coding for isocitrate lyase (ICL) and malate synthase were recently identified in two strains of the genus Cyanothece, and the existence of the complete glyoxylate shunt was verified in a strain of Chlorogloeopsis fritschii. Here, we report that the gene PCC7424_4054 of the strain Cyanothece sp. PCC 7424 encodes an enzymatically active protein that catalyses the reaction of ICL, an enzyme that is specific for the glyoxylate shunt. We demonstrate that ICL activity is induced under alternating day/night cycles and acetate-supplemented cultures exhibit enhanced growth. In contrast, growth under constant light did not result in any detectable ICL activity or enhanced growth of acetate-supplemented cultures. Furthermore, our results indicate that, despite the presence of a glyoxylate shunt, acetate does not support continued heterotrophic growth and cell proliferation. The functional validation of the ICL is supplemented with a bioinformatics analysis of enzymes that co-occur with the glyoxylate shunt. We hypothesize that the glyoxylate shunt in Cyanothece sp. PCC 7424, and possibly other nitrogen-fixing cyanobacteria, is an adaptation to a specific ecological niche and supports assimilation of nitrogen or organic compounds during the night phase.
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Affiliation(s)
- Marianne Gründel
- Fachinstitut Theoretische Biologie (ITB), Institut für Biologie, Humboldt-Universität zu Berlin, Invalidenstraße 43, 10115 Berlin, Germany.,Institut für Biologie, Humboldt-Universität zu Berlin, Chausseestr. 117, 10115 Berlin, Germany
| | - Henning Knoop
- Fachinstitut Theoretische Biologie (ITB), Institut für Biologie, Humboldt-Universität zu Berlin, Invalidenstraße 43, 10115 Berlin, Germany
| | - Ralf Steuer
- Fachinstitut Theoretische Biologie (ITB), Institut für Biologie, Humboldt-Universität zu Berlin, Invalidenstraße 43, 10115 Berlin, Germany
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Lombardo S, Restuccia C, Muratore G, Barbagallo RN, Licciardello F, Pandino G, Scifò GO, Mazzaglia A, Ragonese F, Mauromicale G. Effect of nitrogen fertilisation on the overall quality of minimally processed globe artichoke heads. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2017; 97:650-658. [PMID: 27144811 DOI: 10.1002/jsfa.7784] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 04/26/2016] [Accepted: 04/26/2016] [Indexed: 06/05/2023]
Abstract
BACKGROUND Although nitrogen (N) fertilisation is essential for promoting crop yield, it may also affect the produce quality. Here, the influence of three N fertiliser rates (0 kg ha-1 as a control, 200 kg ha-1 and 400 kg ha-1 referred to as N0 , N200 and N400, respectively) on the overall quality of minimally processed globe artichoke heads was investigated during refrigerated storage for 12 days. RESULTS Throughout the storage time, N fertilised samples had higher inulin contents than those unfertilised. In addition, the respiratory quotient of N200 and N400 samples was 2-fold and 2.5-fold lower than N0 ones, whose values were close to the normal range for vegetables. All the samples reported good microbiological standards, although N200 and N400 achieved lower mesophilic and psychotropic counts than N0 throughout the storage time. After 8 and 12 days of refrigerated storage, the N200 samples showed the highest scores of positive sensory descriptors. CONCLUSION A fertiliser level of 200 kg N ha-1 is suitable for obtaining minimally processed globe artichoke heads with good nutritional, sensory and microbiological quality, characterised by low endogenous oxidase activities. Proper packaging systems and procedures are, however, crucial for extending the product shelf-life and, thus, promoting its exportation on a wider scale. © 2016 Society of Chemical Industry.
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Affiliation(s)
- Sara Lombardo
- Di3A - Dipartimento di Agricoltura, Alimentazione e Ambiente, University of Catania, via Santa Sofia 98, 95123, Catania, Italy
| | - Cristina Restuccia
- Di3A - Dipartimento di Agricoltura, Alimentazione e Ambiente, University of Catania, via Santa Sofia 98, 95123, Catania, Italy
| | - Giuseppe Muratore
- Di3A - Dipartimento di Agricoltura, Alimentazione e Ambiente, University of Catania, via Santa Sofia 98, 95123, Catania, Italy
| | - Riccardo N Barbagallo
- Di3A - Dipartimento di Agricoltura, Alimentazione e Ambiente, University of Catania, via Santa Sofia 98, 95123, Catania, Italy
| | - Fabio Licciardello
- Di3A - Dipartimento di Agricoltura, Alimentazione e Ambiente, University of Catania, via Santa Sofia 98, 95123, Catania, Italy
| | - Gaetano Pandino
- Di3A - Dipartimento di Agricoltura, Alimentazione e Ambiente, University of Catania, via Santa Sofia 98, 95123, Catania, Italy
| | - Giovanna O Scifò
- Di3A - Dipartimento di Agricoltura, Alimentazione e Ambiente, University of Catania, via Santa Sofia 98, 95123, Catania, Italy
| | - Agata Mazzaglia
- Di3A - Dipartimento di Agricoltura, Alimentazione e Ambiente, University of Catania, via Santa Sofia 98, 95123, Catania, Italy
| | - Francesca Ragonese
- Di3A - Dipartimento di Agricoltura, Alimentazione e Ambiente, University of Catania, via Santa Sofia 98, 95123, Catania, Italy
| | - Giovanni Mauromicale
- Di3A - Dipartimento di Agricoltura, Alimentazione e Ambiente, University of Catania, via Santa Sofia 98, 95123, Catania, Italy
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7
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Xu C, Shanklin J. Triacylglycerol Metabolism, Function, and Accumulation in Plant Vegetative Tissues. ANNUAL REVIEW OF PLANT BIOLOGY 2016; 67:179-206. [PMID: 26845499 DOI: 10.1146/annurev-arplant-043015-111641] [Citation(s) in RCA: 149] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Oils in the form of triacylglycerols are the most abundant energy-dense storage compounds in eukaryotes, and their metabolism plays a key role in cellular energy balance, lipid homeostasis, growth, and maintenance. Plants accumulate oils primarily in seeds and fruits. Plant oils are used for food and feed and, increasingly, as feedstocks for biodiesel and industrial chemicals. Although plant vegetative tissues do not accumulate significant levels of triacylglycerols, they possess a high capacity for their synthesis, storage, and metabolism. The development of plants that accumulate oil in vegetative tissues presents an opportunity for expanded production of triacylglycerols as a renewable and sustainable bioenergy source. Here, we review recent progress in the understanding of triacylglycerol synthesis, turnover, storage, and function in leaves and discuss emerging genetic engineering strategies targeted at enhancing triacylglycerol accumulation in biomass crops. Such plants could potentially be modified to produce oleochemical feedstocks or nutraceuticals.
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Affiliation(s)
- Changcheng Xu
- Biology Department, Brookhaven National Laboratory, Upton, New York 11973; ,
| | - John Shanklin
- Biology Department, Brookhaven National Laboratory, Upton, New York 11973; ,
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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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Mansilla N, Garcia L, Gonzalez DH, Welchen E. AtCOX10, a protein involved in haem o synthesis during cytochrome c oxidase biogenesis, is essential for plant embryogenesis and modulates the progression of senescence. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:6761-75. [PMID: 26246612 DOI: 10.1093/jxb/erv381] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Cytochrome c oxidase (CcO) biogenesis requires several accessory proteins implicated, among other processes, in copper and haem a insertion. In yeast, the farnesyltransferase Cox10p that catalyses the conversion of haem b to haem o is the limiting factor in haem a biosynthesis and is essential for haem a insertion in CcO. In this work, we characterized AtCOX10, a putative Cox10p homologue from Arabidopsis thaliana. AtCOX10 was localized in mitochondria and was able to restore growth of a yeast Δcox10 null mutant on non-fermentable carbon sources, suggesting that it also participates in haem o synthesis. Plants with T-DNA insertions in the coding region of both copies of AtCOX10 could not be recovered, and heterozygous mutant plants showed seeds with embryos arrested at early developmental stages that lacked CcO activity. Heterozygous mutant plants exhibited lower levels of CcO activity and cyanide-sensitive respiration but normal levels of total respiration at the expense of an increase in alternative respiration. AtCOX10 seems to be implicated in the onset and progression of senescence, since heterozygous mutant plants showed a faster decrease in chlorophyll content and photosynthetic performance than wild-type plants after natural and dark-induced senescence. Furthermore, complementation of mutants by expressing AtCOX10 under its own promoter allowed us to obtain plants with T-DNA insertions in both AtCOX10 copies, which showed phenotypic characteristics comparable to those of wild type. Our results highlight the relevance of haem o synthesis in plants and suggest that this process is a limiting factor that influences CcO activity levels, mitochondrial respiration, and plant senescence.
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Affiliation(s)
- Natanael Mansilla
- Instituto de Agrobiotecnología del Litoral (CONICET-UNL), Cátedra de Biología Celular y Molecular, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Centro Científico Tecnológico Santa Fe - Colectora Ruta Nacional Nº 168 Km 0, Paraje El Pozo, 3000 Santa Fe, Argentina
| | - Lucila Garcia
- Instituto de Agrobiotecnología del Litoral (CONICET-UNL), Cátedra de Biología Celular y Molecular, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Centro Científico Tecnológico Santa Fe - Colectora Ruta Nacional Nº 168 Km 0, Paraje El Pozo, 3000 Santa Fe, Argentina
| | - Daniel H Gonzalez
- Instituto de Agrobiotecnología del Litoral (CONICET-UNL), Cátedra de Biología Celular y Molecular, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Centro Científico Tecnológico Santa Fe - Colectora Ruta Nacional Nº 168 Km 0, Paraje El Pozo, 3000 Santa Fe, Argentina
| | - Elina Welchen
- Instituto de Agrobiotecnología del Litoral (CONICET-UNL), Cátedra de Biología Celular y Molecular, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Centro Científico Tecnológico Santa Fe - Colectora Ruta Nacional Nº 168 Km 0, Paraje El Pozo, 3000 Santa Fe, Argentina
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10
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Maurino VG, Engqvist MKM. 2-Hydroxy Acids in Plant Metabolism. THE ARABIDOPSIS BOOK 2015; 13:e0182. [PMID: 26380567 PMCID: PMC4568905 DOI: 10.1199/tab.0182] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Glycolate, malate, lactate, and 2-hydroxyglutarate are important 2-hydroxy acids (2HA) in plant metabolism. Most of them can be found as D- and L-stereoisomers. These 2HA play an integral role in plant primary metabolism, where they are involved in fundamental pathways such as photorespiration, tricarboxylic acid cycle, glyoxylate cycle, methylglyoxal pathway, and lysine catabolism. Recent molecular studies in Arabidopsis thaliana have helped elucidate the participation of these 2HA in in plant metabolism and physiology. In this chapter, we summarize the current knowledge about the metabolic pathways and cellular processes in which they are involved, focusing on the proteins that participate in their metabolism and cellular/intracellular transport in Arabidopsis.
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Affiliation(s)
- Veronica G. Maurino
- institute of Developmental and Molecular Biology of Plants, Plant Molecular Physiology and Biotechnology Group, Heinrich Heine University, Universitätsstraße 1, and Cluster of Excellence on Plant Sciences (CEPLAS), 40225 Düsseldorf, Germany
| | - Martin K. M. Engqvist
- institute of Developmental and Molecular Biology of Plants, Plant Molecular Physiology and Biotechnology Group, Heinrich Heine University, Universitätsstraße 1, and Cluster of Excellence on Plant Sciences (CEPLAS), 40225 Düsseldorf, Germany
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Brychkova G, Yarmolinsky D, Batushansky A, Grishkevich V, Khozin-Goldberg I, Fait A, Amir R, Fluhr R, Sagi M. Sulfite Oxidase Activity Is Essential for Normal Sulfur, Nitrogen and Carbon Metabolism in Tomato Leaves. PLANTS 2015; 4:573-605. [PMID: 27135342 PMCID: PMC4844397 DOI: 10.3390/plants4030573] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2015] [Revised: 07/30/2015] [Accepted: 08/07/2015] [Indexed: 11/24/2022]
Abstract
Plant sulfite oxidase [SO; E.C.1.8.3.1] has been shown to be a key player in protecting plants against exogenous toxic sulfite. Recently we showed that SO activity is essential to cope with rising dark-induced endogenous sulfite levels in tomato plants (Lycopersicon esculentum/Solanum lycopersicum Mill. cv. Rheinlands Ruhm). Here we uncover the ramifications of SO impairment on carbon, nitrogen and sulfur (S) metabolites. Current analysis of the wild-type and SO-impaired plants revealed that under controlled conditions, the imbalanced sulfite level resulting from SO impairment conferred a metabolic shift towards elevated reduced S-compounds, namely sulfide, S-amino acids (S-AA), Co-A and acetyl-CoA, followed by non-S-AA, nitrogen and carbon metabolite enhancement, including polar lipids. Exposing plants to dark-induced carbon starvation resulted in a higher degradation of S-compounds, total AA, carbohydrates, polar lipids and total RNA in the mutant plants. Significantly, a failure to balance the carbon backbones was evident in the mutants, indicated by an increase in tricarboxylic acid cycle (TCA) cycle intermediates, whereas a decrease was shown in stressed wild-type plants. These results indicate that the role of SO is not limited to a rescue reaction under elevated sulfite, but SO is a key player in maintaining optimal carbon, nitrogen and sulfur metabolism in tomato plants.
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Affiliation(s)
- Galina Brychkova
- French Associates Institute for Agriculture and Biotechnology of Drylands, Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus 84990, Israel.
| | - Dmitry Yarmolinsky
- French Associates Institute for Agriculture and Biotechnology of Drylands, Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus 84990, Israel.
| | - Albert Batushansky
- French Associates Institute for Agriculture and Biotechnology of Drylands, Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus 84990, Israel.
| | - Vladislav Grishkevich
- French Associates Institute for Agriculture and Biotechnology of Drylands, Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus 84990, Israel.
| | - Inna Khozin-Goldberg
- French Associates Institute for Agriculture and Biotechnology of Drylands, Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus 84990, Israel.
| | - Aaron Fait
- French Associates Institute for Agriculture and Biotechnology of Drylands, Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus 84990, Israel.
| | - Rachel Amir
- Migal-Galilee Technology Center, Southern Industrial Zone, POB831 Kiryat-Shmona 11016, Israel.
| | - Robert Fluhr
- Department of Plant Sciences, Weizmann Institute of Science, P.O.B. 26 Rehovot 76100, Israel.
| | - Moshe Sagi
- French Associates Institute for Agriculture and Biotechnology of Drylands, Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus 84990, Israel.
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Subramanian V, Dubini A, Astling DP, Laurens LML, Old WM, Grossman AR, Posewitz MC, Seibert M. Profiling Chlamydomonas metabolism under dark, anoxic H2-producing conditions using a combined proteomic, transcriptomic, and metabolomic approach. J Proteome Res 2014; 13:5431-51. [PMID: 25333711 DOI: 10.1021/pr500342j] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Chlamydomonas reinhardtii is well adapted to survive under different environmental conditions due to the unique flexibility of its metabolism. Here we report metabolic pathways that are active during acclimation to anoxia, but were previously not thoroughly studied under dark, anoxic H2-producing conditions in this model green alga. Proteomic analyses, using 2D-differential in-gel electrophoresis in combination with shotgun mass fingerprinting, revealed increased levels of proteins involved in the glycolytic pathway downstream of 3-phosphoglycerate, the glyoxylate pathway, and steps of the tricarboxylic acid (TCA) reactions. Upregulation of the enzyme, isocitrate lyase (ICL), was observed, which was accompanied by increased intracellular succinate levels, suggesting the functioning of glyoxylate pathway reactions. The ICL-inhibitor study revealed presence of reverse TCA reactions under these conditions. Contributions of the serine-isocitrate lyase pathway, glycine cleavage system, and c1-THF/serine hydroxymethyltransferase pathway in the acclimation to dark anoxia were found. We also observed increased levels of amino acids (AAs) suggesting nitrogen reorganization in the form of de novo AA biosynthesis during anoxia. Overall, novel routes for reductant utilization, in combination with redistribution of carbon and nitrogen, are used by this alga during acclimation to O2 deprivation in the dark.
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Masterson C, Wood C. Influence of mitochondrial β-oxidation on early pea seedling development. THE NEW PHYTOLOGIST 2009; 181:832-842. [PMID: 19140943 DOI: 10.1111/j.1469-8137.2008.02717.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
This work investigates the role of mitochondrial β-oxidation in early pea (Pisumsativum) seedling development using the epoxy fatty acid etomoxir. Etomoxir was used to effect selective chemical intervention in this biological system. The effect of this intervention on chloroplast structure and membrane composition was determined by transmission electron microscopy and lipidomic analysis by electrospray ionization (ESI) tandem mass spectrometry. β-oxidation was assayed radiochemically using 14C-palmitic acid. Chlorophyll and starch were assayed spectrophotometrically and lipid content determined by soxhlet extraction.Following emergence of the plumule, there was a switch from utilization of starch to lipid by the cotyledons. Etomoxir had a potent inhibitory effect on mitochondrial but not on peroxisomal β-oxidation. Seedlings grown hydroponically in 50 μM etomoxir in the light were phenotypically very different from water-grown controls. Chloroplast structure and fatty acid compositions were altered, etomoxir-treated plants containing more saturated fatty acids in their chloroplast lipids than controls. Etomoxir had no observable phenotypic effect on dark grown seedlings. When etiolated seedlings were exposed to light for 48 h, carnitine (on which mitochondrial β-oxidation depends)stimulated chlorophyll synthesis whilst etomoxir reduced chlorophyll synthesis. The development of newly emergent embryos into independent autotrophic seedlings is dependent upon mitochondrial β-oxidation in the cotyledons.
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Affiliation(s)
- Christine Masterson
- School of Biology, Newcastle University, King George VI Building, King's Road, Newcastle upon Tyne NE1 7RU, UK
| | - Clifford Wood
- School of Biology, Newcastle University, King George VI Building, King's Road, Newcastle upon Tyne NE1 7RU, UK
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Wingler A, Roitsch T. Metabolic regulation of leaf senescence: interactions of sugar signalling with biotic and abiotic stress responses. PLANT BIOLOGY (STUTTGART, GERMANY) 2008; 10 Suppl 1:50-62. [PMID: 18721311 DOI: 10.1111/j.1438-8677.2008.00086.x] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Sugars are important signals in the regulation of plant metabolism and development. During stress and in senescing leaves, sugars often accumulate. In addition, both sugar accumulation and stress can induce leaf senescence. Infection by bacterial and fungal pathogens and attack by herbivores and gall-forming insects may influence leaf senescence via modulation of the sugar status, either by directly affecting primary carbon metabolism or by regulating steady state levels of plant hormones. Many types of biotic interactions involve the induction of extracellular invertase as the key enzyme of an apoplasmic phloem unloading pathway, resulting in a source-sink transition and an increased hexose/sucrose ratio. Induction of the levels of the phytohormones ethylene and jasmonate in biotic interactions results in accelerated senescence, whereas an increase in plant- or pathogen-derived cytokinins delays senescence and results in the formation of green islands within senescing leaves. Interactions between sugar and hormone signalling also play a role in response to abiotic stress. For example, interactions between sugar and abscisic acid (ABA) signalling may be responsible for the induction of senescence during drought stress. Cold treatment, on the other hand, can result in delayed senescence, despite sugar and ABA accumulation. Moreover, natural variation can be found in senescence regulation by sugars and in response to stress: in response to drought stress, both drought escape and dehydration avoidance strategies have been described in different Arabidopsis accessions. The regulation of senescence by sugars may be key to these different strategies in response to stress.
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Affiliation(s)
- A Wingler
- Department of Biology, University College London, Gower Street, London, UK.
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Nayidu NK, Wang L, Xie W, Zhang C, Fan C, Lian X, Zhang Q, Xiong L. Comprehensive sequence and expression profile analysis of PEX11 gene family in rice. Gene 2008; 412:59-70. [PMID: 18291602 DOI: 10.1016/j.gene.2008.01.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2007] [Revised: 01/08/2008] [Accepted: 01/08/2008] [Indexed: 10/22/2022]
Abstract
PEX11 gene family has been shown to be involved in peroxisome biogenesis but very little is known about this gene family in rice. Here we show that five putative PEX11 genes (OsPEX11-1-5) present in rice genome and each contain three conserved motifs. The PEX11 sequences from rice and other species can be classified into three major groups. Among the five rice PEX11 genes, OsPEX11-2 and -3 are most likely duplicated. Expression profile and RT-PCR analysis suggested that the members of PEX11 family in rice had differential expression patterns: OsPEX11-1 and OsPEX11-4 had higher expression levels in leaf tissues than in the other tissues, OsPEX11-2 was detected only in germinated seeds, OsPEX11-3 was expressed predominantly in endosperm and germinated seeds, and OsPEX11-5 was expressed in all the tissues investigated. We also observed that the rice PEX11 genes had differential expression patterns under different abiotic stresses. OsPEX11-1 and OsPEX11-4 were induced by abscisic acid (ABA), hydrogen peroxide (H2O2), salt and low nitrogen stress conditions. OsPEX11-3 was responsive to ABA and H2O2 treatments, and OsPEX11-5 was responsive to ABA, H2O2, and salt treatments. However, OsPEX11-2 had no response to any of the stresses. Our results suggest that the rice PEX11 genes have diversification not only in sequences but also in expression patterns under normal and various stress conditions.
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Affiliation(s)
- Naghabushana K Nayidu
- National Key Laboratory of Crop Genetic Improvement, National Center of Plant Gene Research Wuhan, Huazhong Agricultural University, Wuhan 430070, China
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Identification of genes associated with cotyledon senescence in upland cotton. CHINESE SCIENCE BULLETIN 2006. [DOI: 10.1007/s11434-006-1085-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Parrott D, Yang L, Shama L, Fischer AM. Senescence is accelerated, and several proteases are induced by carbon "feast" conditions in barley (Hordeum vulgare L.) leaves. PLANTA 2005; 222:989-1000. [PMID: 16034594 DOI: 10.1007/s00425-005-0042-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2005] [Accepted: 05/30/2005] [Indexed: 05/03/2023]
Abstract
Leaf senescence is characterized by nitrogen remobilization to developing seeds of annual plants, or surviving organs of perennial species. It has been demonstrated that high carbohydrate levels (carbon "feast") are associated with the onset of the senescence process. Therefore, the development of model systems allowing the manipulation of leaf carbohydrates constitutes a logical first step in the investigation of processes important during early phases of senescence, such as plastidial protein degradation. In this study, sugar accumulation was induced either by the incubation of excised, mature barley (Hordeum vulgare L.) leaves under relatively strong light, or by the interruption of sieve tubes at the base of the leaf lamina by "steam-girdling". Accelerated chlorophyll degradation and net proteolysis confirmed successful senescence induction in both model systems, but suggested that girdled leaves are more useful than excised leaves to study proteolysis. Activities or transcript levels of several proteolytic enzymes, including plastidial (aminopeptidases, Clp protease), cytosolic (proteasome) and vacuolar (thiol proteases, an aspartic protease and a serine carboxypeptidase) proteases were clearly induced under these conditions; some of these genes also reacted to other stimuli such as leaf excision. The most interesting finding was the specific induction of a carboxypeptidase gene (cp-mIII) in girdled leaves accumulating high carbohydrate levels. As a previous study from our laboratory, using a genetic approach, has indicated that one or several carboxypeptidases are involved in leaf N remobilization, the detailed characterization of cp-mIII (and, possibly, closely related genes) may considerably improve our understanding of whole-plant N recycling.
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Affiliation(s)
- D Parrott
- Department of Plant Sciences and Plant Pathology, Montana State University, Bozeman, MT, 59717-3150, USA
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Lu Y, Wu YR, Han B. Anaerobic induction of isocitrate lyase and malate synthase in submerged rice seedlings indicates the important metabolic role of the glyoxylate cycle. Acta Biochim Biophys Sin (Shanghai) 2005; 37:406-14. [PMID: 15944756 DOI: 10.1111/j.1745-7270.2005.00060.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The glyoxylate cycle is a modified form of the tricarboxylic acid cycle that converts C2 compounds into C4 dicarboxylic acids at plant developmental stages. By studying submerged rice seedlings, we revealed the activation of the glyoxylate cycle by identifying the increased transcripts of mRNAs of the genes of isocitrate lyase (ICL) and malate synthase (MS), two characteristic enzymes of the glyoxylate cycle. Northern blot analysis showed that ICL and MS were activated in the prolonged anaerobic environment. The activity assay of pyruvate decarboxylase and ICL in the submerged seedlings indicated an 8.8-fold and 3.5-fold increase over that in the unsubmerged seedlings, respectively. The activity assay of acetyl-coenzyme A synthetase in the submerged seedlings indicated a 3-fold increase over that in the unsubmerged seedlings, which is important for initiating acetate metabolism. Consequently, we concluded that the glyoxylate cycle was involved in acetate metabolism under anaerobic conditions.
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Affiliation(s)
- Ying Lu
- National Center for Gene Research, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200233, China
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Abstract
Peroxisomes, one of single membrane-bound organelles, are present ubiquitously in eukaryotic cells. They were originally identified as organelles for production of hydrogen peroxide, the degradation of its hydrogen peroxide, and metabolism of fatty acids, which are functions common to almost all the organisms. Meanwhile, photorespiration and assimilation of symbiotically induced nitrogen are plant-specific functions. Recent postgenetic approaches such as transcriptome and proteome showed that plant peroxisomes are differentiated in various tissues, and revealed that peroxisomes have more important roles in various metabolic processes including biosynthesis of plant hormones than we speculated. All peroxisomal proteins, including metabolic enzymes in the matrix, membrane proteins, and factors responsible for peroxisome biogenesis, are nuclear encoded, and are provided from the outside of peroxisomes. Peroxisome biogenesis, such as protein transport, division, and enlargement, requires various complicated steps and is one of the most intriguing topics. Analyses using peroxisome biogenesis mutants and the whole-scale sequencing projects among several organisms revealed the existence of essential factors responsible for peroxisome biogenesis such as peroxins. This review addresses a comprehensive issue relating to function and biogenesis of plant peroxisomes and Arabidopsis mutants that have been accelerating our understanding of peroxisomes in planta.
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Affiliation(s)
- Shoji Mano
- Department of Cell Biology, National Institute for Basic Biology Okazaki 444-8585, Japan
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Fargeix C, Gindro K, Widmer F. Soybean (Glycine max. L.) and bacteroid glyoxylate cycle activities during nodular senescence. JOURNAL OF PLANT PHYSIOLOGY 2004; 161:183-90. [PMID: 15022832 DOI: 10.1078/0176-1617-01094] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Soybean (Glycine max. L.) nodular senescence results in the dismantling of the peribacteroid membrane (PBM) and in an increase of soybean isocitrate lyase (ICL; EC 4.1.3.1) and malate synthase (MS; EC 4.1.3.2) mRNA and protein levels. This suggests that in senescing soybean nodular cells, the specific glyoxylate cycle enzyme activities might be induced to reallocate carbon obtained from the PBM degradation. In order to evaluate as well the carbon metabolism of the nitrogen-fixing Bradyrhizobium japonicum endosymbiotic bacteroids during nodular senescence, their glyoxylate cycle activities were also investigated. To this end, partial DNA sequences were isolated from their icl and ms genes, but the corresponding mRNAs were not detected in the microorganisms. It was also observed that the bacteroid ICL and MS activities were negligible during nodular senescence. This suggests that glyoxylate cycle activities are not reinitiated in the bacteroids under these physiological conditions. In case the microorganisms nevertheless feed on the PBM degradation products, this might occur via the citric acid cycle exclusively.
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Affiliation(s)
- Christophe Fargeix
- Laboratory of Plant Biology and Physiology, University Biology Building, CH-1015 Lausanne, Switzerland
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Rylott EL, Gilday AD, Graham IA. The gluconeogenic enzyme phosphoenolpyruvate carboxykinase in Arabidopsis is essential for seedling establishment. PLANT PHYSIOLOGY 2003; 131:1834-42. [PMID: 12692343 PMCID: PMC166940 DOI: 10.1104/pp.102.019174] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2002] [Revised: 01/02/2003] [Accepted: 01/09/2003] [Indexed: 05/18/2023]
Abstract
Phosphoenolpyruvate carboxykinase (PEPCK) catalyzes the conversion of oxaloacetate to phosphoenolpyruvate in the gluconeogenic production of sugars from storage oil in germinating oilseeds. Here, we present the results of analysis on PEPCK antisense Arabidopsis plants with a range of enzyme activities from 20% to 80% of wild-type levels. There is a direct correlation between enzyme activity and seedling establishment during early post-germinative growth, thus demonstrating the absolute requirement of PEPCK and gluconeogenesis in this process. Soluble sugar levels in the 35S-PCK1 antisense seedlings are reduced and seedling establishment can be rescued with an exogenous supply of sucrose. We observed an increase in the respiration of acetyl coenzyme A units released from fatty acid beta-oxidation and a corresponding decrease in the production of sugars with decreasing enzyme activity in 2-d-old antisense seedlings. The 35S-PCK1 antisense lines have a more extreme phenotype when compared with Arabidopsis mutants disrupted in the glyoxylate cycle. We conclude that the 35S-PCK1 antisense seedlings are compromised in the ability to use both storage lipid and storage protein through gluconeogenesis to produce soluble sugars.
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Affiliation(s)
- Elizabeth L Rylott
- Centre for Novel Agricultural Products, Department of Biology (Area 7), University of York, P.O. Box 373, United Kingdom
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Bhalerao R, Keskitalo J, Sterky F, Erlandsson R, Björkbacka H, Birve SJ, Karlsson J, Gardeström P, Gustafsson P, Lundeberg J, Jansson S. Gene expression in autumn leaves. PLANT PHYSIOLOGY 2003; 131:430-42. [PMID: 12586868 PMCID: PMC166820 DOI: 10.1104/pp.012732] [Citation(s) in RCA: 175] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2002] [Revised: 10/09/2002] [Accepted: 11/07/2002] [Indexed: 05/18/2023]
Abstract
Two cDNA libraries were prepared, one from leaves of a field-grown aspen (Populus tremula) tree, harvested just before any visible sign of leaf senescence in the autumn, and one from young but fully expanded leaves of greenhouse-grown aspen (Populus tremula x tremuloides). Expressed sequence tags (ESTs; 5,128 and 4,841, respectively) were obtained from the two libraries. A semiautomatic method of annotation and functional classification of the ESTs, according to a modified Munich Institute of Protein Sequences classification scheme, was developed, utilizing information from three different databases. The patterns of gene expression in the two libraries were strikingly different. In the autumn leaf library, ESTs encoding metallothionein, early light-inducible proteins, and cysteine proteases were most abundant. Clones encoding other proteases and proteins involved in respiration and breakdown of lipids and pigments, as well as stress-related genes, were also well represented. We identified homologs to many known senescence-associated genes, as well as seven different genes encoding cysteine proteases, two encoding aspartic proteases, five encoding metallothioneins, and 35 additional genes that were up-regulated in autumn leaves. We also indirectly estimated the rate of plastid protein synthesis in the autumn leaves to be less that 10% of that in young leaves.
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Affiliation(s)
- Rupali Bhalerao
- Umea Plant Science Center, Department of Plant Physiology, Umea University, 901 87 Umea, Sweden
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Pua EC, Chandramouli S, Han P, Liu P. Malate synthase gene expression during fruit ripening of Cavendish banana (Musa acuminata cv. Williams). JOURNAL OF EXPERIMENTAL BOTANY 2003; 54:309-16. [PMID: 12493858 DOI: 10.1093/jxb/erg030] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Malate synthase (MS) is a key enzyme responsible for malic acid synthesis in the glyoxylate cycle, which functions to convert stored lipids to carbohydrates, by catalysing the glyoxylate condensation reaction with acetyl-CoA in the peroxisome. In this study, the cloning of an MS cDNA, designated MaMS-1, from the banana fruit is reported. MaMS-1 was 1801 bp in length encoding a single polypeptide of 556 amino acid residues. Sequence analysis revealed that MaMS-1 possessed the conserved catalytic domain and a putative peroxisomal targeting signal SK(I/L) at the carboxyl terminal. MaMS-1 also shared an extensive sequence homology (79-81.3%) with other plant MS homologues. Southern analysis indicated that MS might be present as multiple members in the banana genome. In Northern analysis, MaMS-1 was expressed specifically in ripening fruit tissue and transcripts were not detected in other organs such as roots, pseudostem, leaves, ovary, male flower, and in fruit at different stages of development. However, the transcript abundance in fruit was affected by stage of ripening, during which transcript was barely detectable at the early stage of ripening (FG and TY), but the level increased markedly in MG and in other fruits at advanced ripening stages. Furthermore, MaMS-1 expression in FG fruit could be stimulated by treatment with 1 microl l(-1) exogenous ethylene, but the stimulatory effect was abolished by the application of an ethylene inhibitor, norbornadiene. Results of this study clearly show that MS expression in banana fruit is temporally regulated during ripening and is ethylene-inducible.
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Affiliation(s)
- Eng-Chong Pua
- Plant Genetic Engineering Laboratory, Department of Biological Sciences, Faculty of Science, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260, Republic of Singapore.
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Munir E, Hattori T, Shimada M. Purification and characterization of isocitrate lyase from the wood-destroying basidiomycete Fomitopsis palustris grown on glucose. Arch Biochem Biophys 2002; 399:225-31. [PMID: 11888209 DOI: 10.1006/abbi.2002.2770] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Isocitrate lyase (EC 4.1.3.1), a key enzyme in the glyoxylate cycle, was purified 76-fold with 23% yield as an electrophoretically homogeneous protein from the wood-destroying basidiomycete Fomitopsis palustris grown on glucose. The native enzyme has a molecular mass of 186 kDa, consisting of three identical subunits of 60 kDa. The K(m) for DL-isocitrate was found to be 1.6 mM at the optimum pH (7.0). The enzyme required Mg(2+) (K(m) 92 microM) and sulfhydryl compounds for optimal activity. The enzyme activity was strongly inhibited by oxalate and itaconate with a K(i) of 37 and 68 microM, respectively. The inhibition by the glycolysis and tricarboxylic acid cycle intermediates and related compounds suggested that the isocitrate lyase was a regulatory enzyme playing a crucial role in the fungal growth.
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Affiliation(s)
- Erman Munir
- Wood Research Institute, Kyoto University, Uji, Kyoto 611-0011, Japan
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Graham IA, Eastmond PJ. Pathways of straight and branched chain fatty acid catabolism in higher plants. Prog Lipid Res 2002; 41:156-81. [PMID: 11755682 DOI: 10.1016/s0163-7827(01)00022-4] [Citation(s) in RCA: 191] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Significant advances in our knowledge of fatty acid breakdown in plants have been made since the subject was last comprehensively reviewed in the early 1990s. Many of the genes encoding the enzymes of peroxisomal beta-oxidation of straight chain fatty acids have now been identified. Biochemical genetic approaches in the model plant, Arabidopsis thaliana, have been particularly useful not only in the identification and functional characterisation of genes involved in fatty acid beta-oxidation but also in establishing the role of beta-oxidation at different stages in plant development. Advances in our understanding of branched chain amino acid catabolism have provided convincing evidence that mitochondria play an important role in this process. This work is discussed in the context of the long running debate on the sub-cellular localisation of fatty acid beta-oxidation in plants. A significant aspect of this review is that it provides the opportunity to present a comprehensive analysis of the complete Arabidopsis genome sequence for each of the different gene families that are known to be involved in beta-, alpha-, and omega-oxidation of fatty acids in plants. Inevitably, this increase in information, as well as providing many answers also raises many new intriguing questions, particularly as regards the regulation and physiological role of fatty acid catabolism throughout the higher plant life cycle.
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Affiliation(s)
- Ian A Graham
- Centre for Novel Agricultural Products, Department of Biology, University of York, Heslington, YO10 5DD, York, UK.
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Huang YJ, To KY, Yap MN, Chiang WJ, Suen DF, Chen SCG. Cloning and characterization of leaf senescence up-regulated genes in sweet potato. PHYSIOLOGIA PLANTARUM 2001; 113:384-391. [PMID: 12060284 DOI: 10.1034/j.1399-3054.2001.1130312.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Genes that are expressed during leaf senescence in sweet potato (Ipomoea batatas, cv. Tainong 57) were identified by the isolation of cDNA fragments with the mRNA differential display method. Eight senescence-associated cDNA clones for mRNAs differentially expressed during leaf senescence were obtained and characterized. Northern blot analysis indicated that all these clones represented genes that are up-regulated during natural leaf senescence. Among them, five cDNA clones have been obtained in full length by screening a senescing leaf cDNA library or by performing rapid amplification of cDNA ends. DNA and protein database searches revealed that clones SPA15 and SPC9 encode proteins of unknown function. The other six clones SPG31, SPC20, SPG27, SPC25, SPC15 and SPC1 showed significant sequence homology to known genes encoding a cysteine proteinase, isocitrate lyase, S-adenosylmethionine decarboxylase, cysteine proteinase inhibitor and metallothionein-like type I protein. The gene expression patterns represented by SPG31, SPG27 and SPA15 were found to be highly specific in senescing leaves. The corresponding transcripts for SPG31, SPG27 and SPA15 were below detectable levels in other organs such as flowers, stems, roots and tubers. The possible physiological roles of these gene products in the leaf senescence process are discussed.
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Affiliation(s)
- Yih-Jong Huang
- Institute of Biochemistry, National Yang-Ming University, Taipei, Taiwan Institute of BioAgricultural Sciences, Academia Sinica, Taipei, Taiwan Institute of Botany, Academia Sinica, Taipei, Taiwan
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29
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Kaplan CP, Thomas JE, Charlton WL, Baker A. Identification and characterisation of PEX6 orthologues from plants. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1539:173-80. [PMID: 11389979 DOI: 10.1016/s0167-4889(01)00091-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The sunflower (Helianthus annuus) orthologue of PEX6, an AAA ATPase essential for the biogenesis of peroxisomes in yeasts and mammals, was isolated. HaPex6p is immunologically related to Pichia pastoris Pex6p. Like other genes involved in peroxisome biogenesis and function HaPEX6 mRNA and protein levels peak in early post-germinative growth and mRNA levels also increase in senescent tissue. HaPEX6 identifies probable orthologues in Arabidopsis and rice.
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Affiliation(s)
- C P Kaplan
- Centre for Plant Sciences, LIBA, University of Leeds, LS2 9JT, Leeds, UK
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30
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Eastmond PJ, Graham IA. Re-examining the role of the glyoxylate cycle in oilseeds. TRENDS IN PLANT SCIENCE 2001; 6:72-8. [PMID: 11173291 DOI: 10.1016/s1360-1385(00)01835-5] [Citation(s) in RCA: 173] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Oil is the primary seed storage reserve in many higher plants. After germination, this reserve is mobilized in order to support growth during early seedling development. The glyoxylate cycle is instrumental in this metabolic process. It allows acetyl-CoA derived from the breakdown of storage lipids to be used for the synthesis of carbohydrate. Recently, Arabidopsis mutants have been isolated that lack key glyoxylate cycle enzymes. An isocitrate lyase mutant has provided the first opportunity to test the biochemical and physiological functions of the glyoxylate cycle in vivo in an oilseed species.
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Affiliation(s)
- P J Eastmond
- Centre for Novel Agricultural Products, Dept of Biology, University of York, YO10 5DD, York, UK
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31
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Nito K, Yamaguchi K, Kondo M, Hayashi M, Nishimura M. Pumpkin peroxisomal ascorbate peroxidase is localized on peroxisomal membranes and unknown membranous structures. PLANT & CELL PHYSIOLOGY 2001; 42:20-7. [PMID: 11158440 DOI: 10.1093/pcp/pce003] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
To investigate the roles of peroxisomal membrane proteins in the reversible conversion of glyoxysomes to leaf peroxisomes, we characterized several membrane proteins of glyoxysomes. One of them was identified as an ascorbate peroxidase (pAPX) that is localized on glyoxysomal membranes. Its cDNA was isolated by immunoscreening. The deduced amino acid sequence encoded by the cDNA insert does not have a peroxisomal targeting signal (PTS), suggesting that pAPX is imported by one or more PTS-independent pathways. Subcellular fractionation of 3- and 5-d-old cotyledons of pumpkin revealed that pAPX was localized not only in the glyoxysomal fraction, but also in the ER fraction. A magnesium shift experiment showed that the density of pAPX in the ER fraction did not increase in the presence of Mg(2+), indicating that pAPX is not localized in the rough ER. Immunocytochemical analysis using a transgenic Arabidopsis which expressed pumpkin pAPX showed that pAPX was localized on peroxisomal membranes, and also on a unknown membranous structure in green cotyledons. The overall results suggested that pAPX is transported to glyoxysomal membranes via this unknown membranous structure.
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Affiliation(s)
- K Nito
- Department of Cell Biology, National Institute for Basic Biology, Okazaki, 444-8585 Japan
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32
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Matile P. Senescence and Cell Death in Plant Development: Chloroplast Senescence and its Regulation. REGULATION OF PHOTOSYNTHESIS 2001. [DOI: 10.1007/0-306-48148-0_16] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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33
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Chen ZH, Walker RP, Acheson RM, Técsi LI, Wingler A, Lea PJ, Leegood RC. Are isocitrate lyase and phosphoenolpyruvate carboxykinase involved in gluconeogenesis during senescence of barley leaves and cucumber cotyledons? PLANT & CELL PHYSIOLOGY 2000; 41:960-967. [PMID: 11038056 DOI: 10.1093/pcp/pcd021] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The aim of this study was to investigate whether gluconeogenesis catalysed by phosphoenolpyruvate carboxykinase (PEPCK) occurs during leaf senescence. This was addressed by determining changes in the abundance and intercellular location of enzymes necessary for gluconeogenesis during the senescence of barley leaves and cucumber cotyledons. PEPCK was never present in barley leaves, despite the presence of large amounts of isocitrate lyase (ICL), a key enzyme of the glyoxylate cycle, and of its product, glyoxylate. Although PEPCK was present in non-senescent cucumber cotyledons, its abundance declined during senescence. Throughout senescence, PEPCK was only present in the trichomes and vasculature, whereas ICL was located in mesophyll cells. Pyruvate,Pi dikinase (PPDK) which, in concert with NAD(P)-malic enzyme, is also capable of catalysing gluconeogenesis, was present in non-senescent barley leaves and cucumber cotyledons, but in both plants its abundance decreased greatly during senescence. The abundance of ICL was greatly reduced in senescing detached barley leaves by either illumination or by co-incubation with sucrose, and greatly increased in darkened attached barley leaves. These results argue against the large-scale occurrence of gluconeogenesis during senescence catalysed either by PEPCK or PPDK. In cucumber cotyledons, PEPCK may play a role in metabolic processes linked to the export of amino acids, a role in which phosphoenolpyruvate carboxylase may also be involved. The amount of ICL was increased by starvation and during senescence may function in the conversion of lipids to organic acids, which are then utilised in the mobilisation of amino acids from leaf protein.
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Affiliation(s)
- Z H Chen
- Robert Hill Institute and Department of Animal and Plant Sciences, University of Sheffield, UK
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34
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Eastmond PJ, Germain V, Lange PR, Bryce JH, Smith SM, Graham IA. Postgerminative growth and lipid catabolism in oilseeds lacking the glyoxylate cycle. Proc Natl Acad Sci U S A 2000; 97:5669-74. [PMID: 10805817 PMCID: PMC25886 DOI: 10.1073/pnas.97.10.5669] [Citation(s) in RCA: 197] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The glyoxylate cycle is regarded as essential for postgerminative growth and seedling establishment in oilseed plants. We have identified two allelic Arabidopsis mutants, icl-1 and icl-2, which lack the glyoxylate cycle because of the absence of the key enzyme isocitrate lyase. These mutants demonstrate that the glyoxylate cycle is not essential for germination. Furthermore, photosynthesis can compensate for the absence of the glyoxylate cycle during postgerminative growth, and only when light intensity or day length is decreased does seedling establishment become compromised. The provision of exogenous sugars can overcome this growth deficiency. The icl mutants also demonstrate that the glyoxylate cycle is important for seedling survival and recovery after prolonged dark conditions that approximate growth in nature. Surprisingly, despite their inability to catalyze the net conversion of acetate to carbohydrate, mutant seedlings are able to break down storage lipids. Results suggest that lipids can be used as a source of carbon for respiration in germinating oilseeds and that products of fatty acid catabolism can pass from the peroxisome to the mitochondrion independently of the glyoxylate cycle. However, an additional anaplerotic source of carbon is required for lipid breakdown and seedling establishment. This source can be provided by the glyoxylate cycle or, in its absence, by exogenous sucrose or photosynthesis.
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Affiliation(s)
- P J Eastmond
- Plant Molecular Science Group, Division of Biochemistry and Molecular Biology, Institute Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
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35
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Corpas FJ, Barroso JB, Sandalio LM, Palma JM, Lupiáñez JA. Peroxisomal NADP-Dependent Isocitrate Dehydrogenase. Characterization and Activity Regulation during Natural Senescence. PLANT PHYSIOLOGY 1999; 121:921-928. [PMID: 10557241 PMCID: PMC59455 DOI: 10.1104/pp.121.3.921] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/1999] [Accepted: 07/07/1999] [Indexed: 05/20/2023]
Abstract
The peroxisomal localization and characterization of NADP-dependent isocitrate dehydrogenase (perICDH) in young and senescent pea (Pisum sativum) leaves was studied by subcellular fractionation, kinetic analysis, immunoblotting, and immunoelectron microscopy. The subunit molecular mass for perICDH determined by immunoblotting was 46 kD. By isoelectric focusing (IEF) of the peroxisomal matrix fraction, the NADP-ICDH activity was resolved into four isoforms, perICDH-1 to perICDH-4, with isoelectric points (pIs) of 6.0, 5.6, 5.4, and 5.2, respectively. The kinetic properties of the NADP-ICDH in peroxisomes from young and senescent pea leaves were analyzed. The maximum initial velocity was the same in peroxisomes from young and senescent leaves, while the Michaelis constant value in senescent leaf peroxisomes was 11-fold lower than in young leaf peroxisomes. The protein levels of NADP-ICDH in peroxisomes were not altered during senescence. The kinetic behavior of this enzyme suggests a possible fine control of enzymatic activity by modulation of its Michaelis constant during the natural senescence of pea leaves. After embedding, electron microscopy immunogold labeling of NADP-ICDH confirmed that this enzyme was localized in the peroxisomal matrix. Peroxisomal NADP-ICDH represents an alternative dehydrogenase in these cell organelles and may be the main system for the reduction of NADP to NADPH for its re-utilization in the peroxisomal metabolism.
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Affiliation(s)
- FJ Corpas
- Departamento de Bioquímica, Biología Celular y Molecular de Plantas, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Apartado 419, E-18080 Granada, Spain
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36
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Pool MR, López-Huertas E, Horng JT, Baker A. NADPH is a specific inhibitor of protein import into glyoxysomes. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 1998; 15:1-14. [PMID: 9744090 DOI: 10.1046/j.1365-313x.1998.00171.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
We have studied the import of proteins into glyoxysomes in vitro and show that this process is specifically inhibited by NADPH. NADPH affects both binding and translocation of proteins into glyoxysomes, and inhibition is determined by the ratio of NADP+ to NADPH. The site of action of NADPH is most likely within the glyoxysome because (1) pretreatment of glyoxysomes with NADPH, followed by re-isolation of the organelles prior to the import assay, resulted in inhibition of import that could be restored by the addition of NADP+; (2) low concentrations of NADPH inhibited binding of proteins to broken glyoxysome membranes. The sensitivity of protein import to inhibition by NADPH declines as glyoxysomes are converted to leaf-type peroxisomes. A model is proposed that speculates on a possible role for NADPH in regulating protein import into plant peroxisomes.
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Affiliation(s)
- M R Pool
- Centre for Plant Biochemistry and Biotechnology, University of Leeds, UK
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37
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Affiliation(s)
- J E Thompson
- Department of Biology, University of Waterloo, Ontario, Canada
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38
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Kato A, Hayashi M, Takeuchi Y, Nishimura M. cDNA cloning and expression of a gene for 3-ketoacyl-CoA thiolase in pumpkin cotyledons. PLANT MOLECULAR BIOLOGY 1996; 31:843-52. [PMID: 8806414 DOI: 10.1007/bf00019471] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
A cDNA clone for 3-ketoacyl-CoA thiolase (EC 2.3.1.16) was isolated from a lambda gt11 cDNA library constructed from the poly(A)+ RNA of etiolated pumpkin cotyledons. The cDNA insert contained 1682 nucleotides and encoded 461 amino acid residues. A study of the expression in vitro of the cDNA and analysis of the amino-terminal sequence of the protein indicated that pumpkin thiolase is synthesized as a precursor which has a cleavable amino-terminal presequence of 33 amino acids. The amino-terminal presequence was highly homologous to typical amino-terminal signals that target proteins to microbodies. Immunoblot analysis showed that the amount of thiolase increased markedly during germination but decreased dramatically during the light-inducible transition of microbodies from glyoxysomes to leaf peroxisomes. By contrast, the amount of mRNA increased temporarily during the early stage of germination. In senescing cotyledons, the levels of the thiolase mRNA and protein increased again with the reverse transition of microbodies from leaf peroxisomes to glyoxysomes, but the pattern of accumulation of the protein was slightly different from that of malate synthase. These results indicate that expression of the thiolase is regulated in a similar manner to that of other glyoxysomal enzymes, such as malate synthase and citrate synthase, during seed germination and post-germination growth. By contrast, during senescence, expression of the thiolase is regulated in a different manner from that of other glyoxysomal enzymes.
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MESH Headings
- Acetyl-CoA C-Acyltransferase/biosynthesis
- Acetyl-CoA C-Acyltransferase/chemistry
- Acetyl-CoA C-Acyltransferase/genetics
- Amino Acid Sequence
- Base Sequence
- Cloning, Molecular
- Cotyledon/genetics
- DNA, Complementary/genetics
- DNA, Plant/genetics
- Gene Expression Regulation, Enzymologic/physiology
- Gene Expression Regulation, Enzymologic/radiation effects
- Gene Expression Regulation, Plant/physiology
- Gene Expression Regulation, Plant/radiation effects
- Genes, Plant/genetics
- Light
- Microbodies
- Molecular Sequence Data
- Molecular Weight
- Protein Precursors/biosynthesis
- Protein Precursors/chemistry
- Protein Sorting Signals/genetics
- RNA, Messenger/biosynthesis
- RNA, Plant/analysis
- Recombinant Fusion Proteins/biosynthesis
- Recombinant Fusion Proteins/chemistry
- Sequence Homology, Amino Acid
- Time Factors
- Vegetables/enzymology
- Vegetables/genetics
- Vegetables/growth & development
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Affiliation(s)
- A Kato
- Department of Cell Biology, National Institute for Basic Biology, Okazaki, Japan
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39
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Sarah CJ, Graham IA, Reynolds SJ, Leaver CJ, Smith SM. Distinct cis-acting elements direct the germination and sugar responses of the cucumber malate synthase gene. MOLECULAR & GENERAL GENETICS : MGG 1996; 250:153-61. [PMID: 8628214 DOI: 10.1007/bf02174174] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The malate synthase gene (ms) promoter in cucumber (Cucumis sativus L.) was investigated with the aim of distinguishing DNA sequences mediating regulation of gene expression by sugar, and expression following seed germination. Promoter deletions were constructed and their ability to direct expression of the beta-glucuronidase (gus) reporter gene was investigated in transgenic Nicotiana plumbaginifolia. Gene expression was assayed in germinating seeds and developing seedlings (the germination response) and in seedlings transferred from light into darkness with and without sucrose (the sugar response). As progressively more of the promoter was deleted from the 5' end, first the sugar response and then the germination response was lost. Thus, distinct regions of the promoter are required for carbohydrate control and for regulation of gene expression in response to germination. Sequence comparisons of the ms promoter with that of the isocitrate lyase gene (icl) of cucumber have previously identified four IMH(ICL-MS-Homology) sequences. One such sequence, IMH2, is shown here to be implicated in the sugar response of the ms gene. The 17 bp sequences which when deleted from the ms gene results in loss of the germination response, contains a 14 bp sequence which is similar to a sequence in the icl promoter, which we refer to as IMH5. Furthermore, this sequence has similarity with amdI9-like sequences in filamentous fungi, which confer facB-mediated acetate inducibility on several genes, including those encoding ICL and MS.
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Affiliation(s)
- C J Sarah
- Institute of Cell and Molecular Biology, University of Edinburgh, UK
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40
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Hanfrey C, Fife M, Buchanan-Wollaston V. Leaf senescence in Brassica napus: expression of genes encoding pathogenesis-related proteins. PLANT MOLECULAR BIOLOGY 1996; 30:597-609. [PMID: 8605308 DOI: 10.1007/bf00049334] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Genes that are expressed during leaf senescence in Brassica napus were identified by the isolation of representative cDNA clones. DNA sequence and deduced protein sequence from two senescence-related cDNAs, LSC94 and LSC222, representing genes that are expressed early in leaf senescence before any yellowing of the leaves is visible, showed similarities to genes for pathogenesis-related (PR) proteins: a PR-1a-like protein and a class IV chitinase, respectively. The LSC94 and LSC222 genes showed differential regulation with respect to each other; an increase in expression was detected at different times during development of healthy leaves. Expression of both genes was induced by salicylic acid treatment. These findings suggest that some PR genes, as well as being induced by pathogen infection, may have alternative functions during plant development, for example in the process of leaf senescence.
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Affiliation(s)
- C Hanfrey
- Plant Molecular Biology Laboratory, Department of Biological Sciences, Wye College, University of London, Ashford, Kent, UK
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41
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Reynolds SJ, Smith SM. Regulation of expression of the cucumber isocitrate lyase gene in cotyledons upon seed germination and by sucrose. PLANT MOLECULAR BIOLOGY 1995; 29:885-96. [PMID: 8555453 DOI: 10.1007/bf00014963] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
A 6.5 kb cucumber genomic DNA fragment containing the icl gene was introduced into Nicotiana plumbaginifolia and shown to direct isocitrate lyase (ICL) mRNA synthesis in transgenic seedlings upon germination, in a temporally regulated manner. Two putative icl promoter fragments, of 2900 and 572 bp, were subsequently linked to the GUS reporter gene and introduced into N. plumbaginifolia. Both constructs directed GUS expression after transgenic seed germination, and although the 572 bp fragment gave only 1% of the activity of the 2900 bp fragment, it directed expression in the same cotyledon-specific and temporally regulated pattern. Seedlings were transferred to darkness after 18 days growth in the light, to induce a starvation response. The 2900 bp construct was activated by starvation and repressed by exogenous sucrose, whereas the 572 bp construct was not starvation-responsive. To localize the region of the 2900 bp promoter fragment which is responsible for regulation by sucrose, further deletions were made, linked to GUS, and assayed in a cucumber protoplast transient assay system. Constructs with promoters of 2900, 2142 and 1663 bp were activated by starvation and repressed by sucrose, but promoters of 1142 and 572 bp showed no such response. We conclude that the icl gene promoter contains at least two distinct cis-acting elements, one required for the response to sucrose and the other which participates in expression upon seed germination.
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Affiliation(s)
- S J Reynolds
- Institute of Cell and Molecular Biology, University of Edinburgh, UK
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42
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Reynolds SJ, Smith SM. The isocitrate lyase gene of cucumber: isolation, characterisation and expression in cotyledons following seed germination. PLANT MOLECULAR BIOLOGY 1995; 27:487-497. [PMID: 7894014 DOI: 10.1007/bf00019316] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The cucumber (Cucumis sativus L.) genome contains only a single gene encoding the glyoxylate cycle enzyme isocitrate lyase (ICL). The cucumber icl gene has been isolated and sequenced, revealing only two small introns. The predicted amino acid sequence is more than 85% identical to ICL from other higher plants, and contains the C-terminal tripeptide Ser-Arg-Met which resembles a peroxisomal targeting sequence. The icl gene is coordinately expressed with the malate synthase (ms) gene after seed germination in both the light and the dark, suggesting that these genes may contain similar DNA elements regulating transcription. The start of transcription of the icl gene was determined and the DNA sequences upstream compared with the region of the ms gene promoter known to regulate transcription. This comparison revealed a highly conserved DNA sequence at similar positions in each gene.
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Affiliation(s)
- S J Reynolds
- Institute of Cell and Molecular Biology, University of Edinburgh, UK
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43
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Kim DJ, Smith SM. Molecular cloning of cucumber phosphoenolpyruvate carboxykinase and developmental regulation of gene expression. PLANT MOLECULAR BIOLOGY 1994; 26:423-434. [PMID: 7948888 DOI: 10.1007/bf00039551] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
A cDNA library from RNA of senescing cucumber cotyledons was screened for sequences also expressed in cotyledons during post-germinative growth. One clone encodes ATP-dependent phosphoenolpyruvate carboxykinase (PCK; EC 4.1.1.49), an enzyme of the gluconeogenic pathway. The sequence of a full-length cDNA predicts a polypeptide of 74,397 Da which is 43%, 49% and 57% identical to bacterial, trypanosome and yeast enzymes, respectively. The cDNA was expressed in Escherichia coli and antibodies raised against the resultant protein. The antibody recognises a single polypeptide of ca. 74 kDa, in extracts of cotyledons, leaves and roots. The cucumber genome contains a single pck gene. In the seven-day period after seed imbibition, PCK mRNA and protein steady-state levels increase in amount in cotyledons, peaking at days 2 and 3 respectively, and then decrease. Both accumulate again to a low level in senescing cotyledons. This pattern of gene expression is similar to that of isocitrate lyase (ICL) and malate synthase (MS). When green cotyledons are detached from seedlings and incubated in the dark, ICL and MS mRNAs increase rapidly in amount but PCK mRNA does not. Therefore it seems unlikely that the glyoxylate cycle serves primarily a gluconeogenic role in starved (detached) cotyledons, in contrast to post-germinative and senescing cotyledons where PCK, ICL and MS are coordinately synthesised. While exogenous sucrose greatly represses expression of icl and ms genes in dark-incubated cotyledons, it has a smaller effect on the level of PCK mRNA.
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Affiliation(s)
- D J Kim
- Institute of Cell and Molecular Biology, University of Edinburgh, Scotland
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44
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Abstract
Leaf senescence is a hiphly-controlled sequence of events comprising the final stage of development. Cells remain viable during the process and new gene expression is required. There is some similarity between senescence in plants and programmed cell death in animals. In this review, different classes of senescence-related genes are defined and progress towards isolating such genes is reported. A range of internal and external factors which appear to cause leaf senescence is considered and various models for the mechanism of senescence- initiation are described. The current understanding of senescence at the wrganelle and molecular levels is presented. Finally, same ideas are mooted as to why senescence occurs and why it should be studied further. Contents Summary 419 I. Introduction 420 II. Internal factors that cause senescence 423 III. External factors that cause senescence 427 IV. What is the mechanism of senescence initiation? 428 V. Progress in the understanding of organelle senescence 431 VI. Progress in the understanding of senescence at the molecular level 434 VII. The control of senescence in animals and plants 440 VIII. Why is senescence necessary? 441 IX. Why study senescence? 441 References 442.
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Affiliation(s)
- Catherine M Smart
- Cell Biology Department, Institute of Grassland and Environment Research, Plas Gogerddan, Aberystwyth, Dyfed, SY23 3EB, Wales, UK
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45
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Zhang JZ, Gomez-Pedrozo M, Baden CS, Harada JJ. Two classes of isocitrate lyase genes are expressed during late embryogeny and postgermination in Brassica napus L. MOLECULAR & GENERAL GENETICS : MGG 1993; 238:177-84. [PMID: 8479425 DOI: 10.1007/bf00279545] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We have analyzed the structure of genes encoding the glyoxylate cycle enzyme isocitrate lyase from Brassica napus L. and their expression during embryogeny and postgermination. Restriction mapping, nucleotide sequence, and DNA gel blot hybridization analyses of cDNA and genomic clones indicated that there are approximately six isocitrate lyase genes in the B. napus genome that can be divided into at least two subfamilies based upon their divergence in 5' and 3' untranslated regions. We showed previously that isocitrate lyase mRNA accumulates during late embryogeny and postgermination. Here, we present results which indicate that several isocitrate lyase genes are expressed at both stages of development. First, gene-specific probes were used to show that mRNAs encoded by representatives of both gene subfamilies accumulated in both late maturation stage embryos and in seedlings of B. napus. Second, a single B. napus isocitrate lyase gene, together with 3.5 kb and 1.4 kb of 5' and 3' flanking regions, respectively, was expressed in both embryos and seedlings of transgenic tobacco plants. The results indicated that accumulation of isocitrate lyase in late embryogeny and postgermination does not result from the alternate expression of distinct members of the gene family.
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Affiliation(s)
- J Z Zhang
- Section of Botany, University of California, Davis 95616
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46
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del Río LA, Sandalio LM, Palma JM, Bueno P, Corpas FJ. Metabolism of oxygen radicals in peroxisomes and cellular implications. Free Radic Biol Med 1992; 13:557-80. [PMID: 1334030 DOI: 10.1016/0891-5849(92)90150-f] [Citation(s) in RCA: 201] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Peroxisomes are subcellular respiratory organelles which contain catalase and H2O2-producing flavin oxidases as basic enzymatic constituents. These organelles have an essentially oxidative type of metabolism and have the potential to carry out different important metabolic pathways. In recent years the presence of different types of superoxide dismutase (SOD) have been demonstrated in peroxisomes from several plant species, and more recently the occurrence of SOD has been extended to peroxisomes from human and transformed yeast cells. A copper,zinc-containing SOD from plant peroxisomes has been purified and partially characterized. The production of hydroxyl and superoxide radicals has been studied in peroxisomes. There are two sites of O2- production in peroxisomes: (1) in the matrix, the generating system being xanthine oxidase; and (2) in peroxisomal membranes, dependent on reduced nicotinamide adenine dinucleotide (NADH), and the electron transport components of the peroxisomal membrane are possibly responsible. The generation of oxygen radicals in peroxisomes could have important effects on cellular metabolism. Diverse cellular implications of oxyradical metabolism in peroxisomes are discussed in relation to phenomena such as cell injury, peroxisomal genetic diseases, peroxisome proliferation and oxidative stress, metal and salt stress, catabolism of nucleic acids, senescence, and plant pathogenic processes.
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Affiliation(s)
- L A del Río
- Unidad de Bioquímica Vegetal, Estación Experimental del Zaidín, CSIC, Granada, Spain
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47
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Khan AS, Van Driessche E, Kanarek L, Beeckmans S. The purification and physicochemical characterization of maize (Zea mays L.) isocitrate lyase. Arch Biochem Biophys 1992; 297:9-18. [PMID: 1637186 DOI: 10.1016/0003-9861(92)90634-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A purification scheme is described for the glyoxylate cycle enzyme isocitrate lyase from maize scutella. Purification involves an acetone precipitation and a heat denaturation step, followed by ammonium sulfate precipitation and chromatography on DEAE-cellulose and on blue-Sepharose. The latter step results in the removal of the remaining malate dehydrogenase activity, and of a high molecular mass (62 kDa) but inactive degradation product of isocitrate lyase. Catalase can be completely removed by performing the DEAE-cellulose chromatography in the presence of Triton X-100. Pure isocitrate lyase can be stored without appreciable loss of activity at -70 degrees C in 5 mM triethanolamine buffer containing 6 mM MgCl2, 7 mM 2-mercaptoethanol, and 50% (v/v) glycerol, pH 7.6. Maize isocitrate lyase is a tetrameric protein with a subunit molecular mass of 64 kDa. Purity of the enzyme preparation was demonstrated by polyacrylamide gel electrophoresis in the presence of dodecylsulfate, in acid (pH 3.2) urea and by isoelectric focusing (pI = 5.1). Maize isocitrate lyase is devoid of covalently linked sugar residues. From circular dichroism measurements we estimate that its structure comprises 30% alpha-helical and 15% beta-pleated sheet segments. The enzyme requires Mg2+ ions for activity, and only Mn2+ apparently is able to replace this cation to a certain extent. The kinetics of the isocitrate lyase-catalyzed cleavage reaction were investigated, and the amino acid composition of the maize enzyme was determined. Finally the occurrence of an association between maize isocitrate lyase and catalase was observed. Such a multienzyme complex may be postulated to play a protective role in vivo.
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Affiliation(s)
- A S Khan
- Laboratorium voor Chemie der Proteïnen, Vrije Universiteit Brussel, Belgium
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48
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Affiliation(s)
- B Gerhardt
- Institut für Botanik, Universität Münster, Germany
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49
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Graham IA, Smith LM, Leaver CJ, Smith SM. Developmental regulation of expression of the malate synthase gene in transgenic plants. PLANT MOLECULAR BIOLOGY 1990; 15:539-49. [PMID: 2102373 DOI: 10.1007/bf00017829] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
The cucumber malate synthase (MS) gene, including 1856 bp of 5' non-transcribed sequence, has been transferred into Petunia (Mitchell) and Nicotiana plumbaginifolia plants using an Agrobacterium binary vector. The transferred gene is found in variable copy number in different transformants, and is stably transmitted in each case as a single Mendelian character. Transgene mRNA accumulates in the seedling during the first three days of germination, then declines in amount as the cotyledons emerge from the seed. The decline is more pronounced in light-grown seedlings than in dark-grown seedlings. Expression of the MS transgene is also detected at a low level in petals of transformed Petunia plants. In these respects the pattern of MS gene expression is similar in cucumber and in transformed plants, showing that the transferred DNA fragment contains a functional MS gene. A 1076 bp fragment of 5' sequence was linked to the beta-glucuronidase reporter gene and transferred into Nicotiana, where it was shown to direct temporal and spatial patterns of expression similar to that of the complete MS gene. However, histochemical localisation of beta-glucuronidase activity demonstrated that the chimaeric gene is expressed not only in cotyledons of transgenic plants, but also in endosperm and some hypocotyl cells during early germination. The relevance of these findings to the control of malate synthase gene expression is discussed.
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Affiliation(s)
- I A Graham
- Department of Botany, University of Edinburgh, U.K
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