1
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Baker CR, Cocuron JC, Alonso AP, Niyogi KK. Time-resolved systems analysis of the induction of high photosynthetic capacity in Arabidopsis during acclimation to high light. THE NEW PHYTOLOGIST 2023; 240:2335-2352. [PMID: 37849025 DOI: 10.1111/nph.19324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 09/19/2023] [Indexed: 10/19/2023]
Abstract
Induction of high photosynthetic capacity is a key acclimation response to high light (HL) for many herbaceous dicot plants; however, the signaling pathways that control this response remain largely unknown. Here, a systems biology approach was utilized to characterize the induction of high photosynthetic capacity in strongly and weakly acclimating Arabidopsis thaliana accessions. Plants were grown for 5 wk in a low light (LL) regime, and time-resolved photosynthetic physiological, metabolomic, and transcriptomic responses were measured during subsequent exposure to HL. The induction of high nitrogen (N) assimilation rates early in the HL shift was strongly predictive of the induction of photosynthetic capacity later in the HL shift. Accelerated N assimilation rates depended on the mobilization of existing organic acid (OA) reserves and increased de novo OA synthesis during the induction of high photosynthetic capacity. Enhanced sucrose biosynthesis capacity increased in tandem with the induction of high photosynthetic capacity, and increased starch biosynthetic capacity was balanced by increased starch catabolism. This systems analysis supports a model in which the efficient induction of N assimilation early in the HL shift begins the cascade of events necessary for the induction of high photosynthetic capacity acclimation in HL.
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Affiliation(s)
- Christopher R Baker
- Department of Plant and Microbial Biology, Howard Hughes Medical Institute, University of California, Berkeley, CA, 94720-3102, USA
| | | | - Ana Paula Alonso
- BioAnalytical Facility, University of North Texas, Denton, TX, 76201, USA
- Department of Biological Sciences, BioDiscovery Institute, University of North Texas, Denton, TX, 76201, USA
| | - Krishna K Niyogi
- Department of Plant and Microbial Biology, Howard Hughes Medical Institute, University of California, Berkeley, CA, 94720-3102, USA
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
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2
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Lloyd MK, Stein RA, Ibarra DE, Barclay RS, Wing SL, Stahle DW, Dawson TE, Stolper DA. Isotopic clumping in wood as a proxy for photorespiration in trees. Proc Natl Acad Sci U S A 2023; 120:e2306736120. [PMID: 37931112 PMCID: PMC10655223 DOI: 10.1073/pnas.2306736120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 09/22/2023] [Indexed: 11/08/2023] Open
Abstract
Photorespiration can limit gross primary productivity in terrestrial plants. The rate of photorespiration relative to carbon fixation increases with temperature and decreases with atmospheric [CO2]. However, the extent to which this rate varies in the environment is unclear. Here, we introduce a proxy for relative photorespiration rate based on the clumped isotopic composition of methoxyl groups (R-O-CH3) in wood. Most methoxyl C-H bonds are formed either during photorespiration or the Calvin cycle and thus their isotopic composition may be sensitive to the mixing ratio of these pathways. In water-replete growing conditions, we find that the abundance of the clumped isotopologue 13CH2D correlates with temperature (18-28 °C) and atmospheric [CO2] (280-1000 ppm), consistent with a common dependence on relative photorespiration rate. When applied to a global dataset of wood, we observe global trends of isotopic clumping with climate and water availability. Clumped isotopic compositions are similar across environments with temperatures below ~18 °C. Above ~18 °C, clumped isotopic compositions in water-limited and water-replete trees increasingly diverge. We propose that trees from hotter climates photorespire substantially more than trees from cooler climates. How increased photorespiration is managed depends on water availability: water-replete trees export more photorespiratory metabolites to lignin whereas water-limited trees either export fewer overall or direct more to other sinks that mitigate water stress. These disparate trends indicate contrasting responses of photorespiration rate (and thus gross primary productivity) to a future high-[CO2] world. This work enables reconstructing photorespiration rates in the geologic past using fossil wood.
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Affiliation(s)
- Max K. Lloyd
- Department of Earth and Planetary Science, University of California, Berkeley, CA94720
- Department of Geosciences, The Pennsylvania State University, University Park, PA16802
| | - Rebekah A. Stein
- Department of Earth and Planetary Science, University of California, Berkeley, CA94720
- Department of Chemistry and Physical Sciences, Quinnipiac University, Hamden, CT06518
| | - Daniel E. Ibarra
- Department of Earth and Planetary Science, University of California, Berkeley, CA94720
- Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, RI02912
| | - Richard S. Barclay
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC20560
| | - Scott L. Wing
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC20560
| | - David W. Stahle
- Department of Geosciences, University of Arkansas, Fayetteville, AR72701
| | - Todd E. Dawson
- Department of Integrative Biology, University of California, Berkeley, CA94720
| | - Daniel A. Stolper
- Department of Earth and Planetary Science, University of California, Berkeley, CA94720
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3
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Fu X, Walker BJ. Dynamic response of photorespiration in fluctuating light environments. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:600-611. [PMID: 35962786 DOI: 10.1093/jxb/erac335] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 08/09/2022] [Indexed: 06/15/2023]
Abstract
Photorespiration is a dynamic process that is intimately linked to photosynthetic carbon assimilation. There is a growing interest in understanding carbon assimilation during dynamic conditions, but the role of photorespiration under such conditions is unclear. In this review, we discuss recent work relevant to the function of photorespiration under dynamic conditions, with a special focus on light transients. This work reveals that photorespiration is a fundamental component of the light induction of assimilation where variable diffusive processes limit CO2 exchange with the atmosphere. Additionally, metabolic interactions between photorespiration and the C3 cycle may help balance fluxes under dynamic light conditions. We further discuss how the energy demands of photorespiration present special challenges to energy balancing during dynamic conditions. We finish the review with an overview of why regulation of photorespiration may be important under dynamic conditions to maintain appropriate fluxes through metabolic pathways related to photorespiration such as nitrogen and one-carbon metabolism.
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Affiliation(s)
- Xinyu Fu
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA
| | - Berkley J Walker
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA
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4
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Fu X, Gregory LM, Weise SE, Walker BJ. Integrated flux and pool size analysis in plant central metabolism reveals unique roles of glycine and serine during photorespiration. NATURE PLANTS 2023; 9:169-178. [PMID: 36536013 DOI: 10.1038/s41477-022-01294-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 10/28/2022] [Indexed: 06/17/2023]
Abstract
Photorespiration is an essential process juxtaposed between plant carbon and nitrogen metabolism that responds to dynamic environments. Photorespiration recycles inhibitory intermediates arising from oxygenation reactions catalysed by Rubisco back into the C3 cycle, but it is unclear what proportions of its nitrogen-containing intermediates (glycine and serine) are exported into other metabolisms in vivo and how these pool sizes affect net CO2 gas exchange during photorespiratory transients. Here, to address this uncertainty, we measured rates of amino acid export from photorespiration using isotopically non-stationary metabolic flux analysis. This analysis revealed that ~23-41% of the photorespiratory carbon was exported from the pathway as serine under various photorespiratory conditions. Furthermore, we determined that the build-up and relaxation of glycine pools constrained a large portion of photosynthetic acclimation during photorespiratory transients. These results reveal the unique and important roles of glycine and serine in successfully maintaining various photorespiratory fluxes that occur under environmental fluctuations in nature and providing carbon and nitrogen for metabolism.
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Affiliation(s)
- Xinyu Fu
- Michigan State University-Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, USA
| | - Luke M Gregory
- Michigan State University-Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, USA
- Department of Plant Biology, Michigan State University, East Lansing, MI, USA
| | - Sean E Weise
- Michigan State University-Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, USA
| | - Berkley J Walker
- Michigan State University-Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, USA.
- Department of Plant Biology, Michigan State University, East Lansing, MI, USA.
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5
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Duan Y, Ren W, Zhao J, Luo C, Liu Y. Planting Cyperus esculentus augments soil microbial biomass and diversity, but not enzymatic activities. PeerJ 2022; 10:e14199. [PMID: 36258793 PMCID: PMC9573350 DOI: 10.7717/peerj.14199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 09/16/2022] [Indexed: 01/24/2023] Open
Abstract
The planting of Cyperus esculentus, a member of the grass family Cyperaceae which includes nut sedge weeds, is being increasingly promoted in northern China's semi-arid and arid regions. Yet the effects of planting C. esculentus upon soil quality and soil microbial characteristics of sandy land remain unclear. This study examined the short-term (1 year) impact of this grass species on soil microbial biomass indices, enzymatic activities, and microbiome characteristics in the Horqin Sandy Land area of China. The results show that planting C. esculentus could increase microbial biomass in the form of carbon (MBC), nitrogen (MBN), and phosphorus (MBP), but it negligibly influenced the enzymatic activities of soil β-1,4-glucosidase (BG), cellobiohydrolase (CBH), leucine aminopeptidase (LAP), and β-1,4-N-acetaminoglycosidase (NAG). Over 1 year, we found that planting C. esculentus significantly increased the soil bacterial richness and diversity of sandy land, yet also altered community composition of soil bacteria and eukaryotes in way that could promote their homogenization. In this respect, the relative abundances of Acidobacteria and Proteobacteria significantly decreased and increased, respectively; hence, they may be considered for use as important indicators of soil nutrient-rich conditions. Overall, the results could be explained by greater soil organic carbon (SOC) and total nitrogen (TN), mainly derived from cumulative plant litter input to soils, which then increased the sandy soil's C:N ratio. Future research should focus on exploring the long-term effects of planting C. esculentus on soil quality and soil microbial characteristics of sandy lands in China and abroad.
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Affiliation(s)
- Yulong Duan
- Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, Gansu, China,Naiman Desertification Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Tongliao, China
| | - Wei Ren
- Agricultural Biotechnology Institute, Jilin Academy of Agricultural Sciences, Changchun, China
| | - Jianhua Zhao
- Shanghai Majorbio Bio-pharm Technology Co., Ltd, Shanghai, China
| | - Chun Luo
- Shanghai Majorbio Bio-pharm Technology Co., Ltd, Shanghai, China
| | - Yang Liu
- Gansu Institute of Architectural Design and Research Company, Lanzhou, Gansu, China
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6
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Mincke J, Courtyn J, Vanhove C, Vandenberghe S, Steppe K. Guide to Plant-PET Imaging Using 11CO 2. FRONTIERS IN PLANT SCIENCE 2021; 12:602550. [PMID: 34149742 PMCID: PMC8206809 DOI: 10.3389/fpls.2021.602550] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 05/03/2021] [Indexed: 05/12/2023]
Abstract
Due to its high sensitivity and specificity for tumor detection, positron emission tomography (PET) has become a standard and widely used molecular imaging technique. Given the popularity of PET, both clinically and preclinically, its use has been extended to study plants. However, only a limited number of research groups worldwide report PET-based studies, while we believe that this technique has much more potential and could contribute extensively to plant science. The limited application of PET may be related to the complexity of putting together methodological developments from multiple disciplines, such as radio-pharmacology, physics, mathematics and engineering, which may form an obstacle for some research groups. By means of this manuscript, we want to encourage researchers to study plants using PET. The main goal is to provide a clear description on how to design and execute PET scans, process the resulting data and fully explore its potential by quantification via compartmental modeling. The different steps that need to be taken will be discussed as well as the related challenges. Hereby, the main focus will be on, although not limited to, tracing 11CO2 to study plant carbon dynamics.
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Affiliation(s)
- Jens Mincke
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
- MEDISIP - INFINITY - IBiTech, Department of Electronics and Information Systems, Faculty of Engineering and Architecture, Ghent University, Ghent, Belgium
| | - Jan Courtyn
- Medical Molecular Imaging and Therapy, Department of Radiology and Nuclear Medicine, Ghent University Hospital, Ghent, Belgium
| | - Christian Vanhove
- MEDISIP - INFINITY - IBiTech, Department of Electronics and Information Systems, Faculty of Engineering and Architecture, Ghent University, Ghent, Belgium
| | - Stefaan Vandenberghe
- MEDISIP - INFINITY - IBiTech, Department of Electronics and Information Systems, Faculty of Engineering and Architecture, Ghent University, Ghent, Belgium
| | - Kathy Steppe
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
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7
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13C Isotope Labelling to Follow the Flux of Photorespiratory Intermediates. PLANTS 2021; 10:plants10030427. [PMID: 33668274 PMCID: PMC7996249 DOI: 10.3390/plants10030427] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 02/18/2021] [Accepted: 02/19/2021] [Indexed: 12/04/2022]
Abstract
Measuring the carbon flux through metabolic pathways in intact illuminated leaves remains challenging because of, e.g., isotopic dilution by endogenous metabolites, the impossibility to reach isotopic steady state, and the occurrence of multiple pools. In the case of photorespiratory intermediates, our knowledge of the partitioning between photorespiratory recycling, storage, and utilization by other pathways is thus rather limited. There has been some controversy as to whether photorespiratory glycine and serine may not be recycled, thus changing the apparent stoichiometric coefficient between photorespiratory O2 fixation and CO2 release. We describe here an isotopic method to trace the fates of glycine, serine and glycerate, taking advantage of positional 13C content with NMR and isotopic analyses by LC–MS. This technique is well-adapted to show that the proportion of glycerate, serine and glycine molecules escaping photorespiratory recycling is very small.
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8
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Tcherkez G, Limami AM. Net photosynthetic CO 2 assimilation: more than just CO 2 and O 2 reduction cycles. THE NEW PHYTOLOGIST 2019; 223:520-529. [PMID: 30927445 DOI: 10.1111/nph.15828] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 03/24/2019] [Indexed: 06/09/2023]
Abstract
Net photosynthetic assimilation in C3 plants is mostly viewed as a simple balance between CO2 fixation by Rubisco-catalyzed carboxylation and CO2 production by photorespiration (and to a lower extent, by day respiration) that can be easily manipulated during gas exchange experiments using the CO2 : O2 ratio of the environment. However, it now becomes clear that it is not so simple, because the photosynthetic response to gaseous conditions involves 'ancillary' metabolisms, even in the short-term. That is, carbon and nitrogen utilization by pathways other than the Calvin cycle and the photorespiratory cycle, as well as rapid signaling events, can influence the observed rate of net photosynthesis. The potential impact of such ancillary metabolisms is assessed as well as how it must be taken into account to avoid misinterpretation of photosynthetic CO2 response curves or low O2 effects in C3 leaves.
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Affiliation(s)
- Guillaume Tcherkez
- Research School of Biology, Australian National University, Canberra, 2601, ACT, Australia
| | - Anis M Limami
- IRHS Centre INRA d'Angers, Université d'Angers, 42 rue George Morel, 49070, Beaucouzé, France
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9
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Normalization of 11C-autoradiographic images for semi-quantitative analysis of woody tissue photosynthesis. ACTA ACUST UNITED AC 2018. [DOI: 10.17660/actahortic.2018.1222.6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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10
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Busch FA, Sage RF, Farquhar GD. Plants increase CO 2 uptake by assimilating nitrogen via the photorespiratory pathway. NATURE PLANTS 2018; 4:46-54. [PMID: 29229957 DOI: 10.1038/s41477-017-0065-x] [Citation(s) in RCA: 105] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 10/27/2017] [Indexed: 05/20/2023]
Abstract
Photorespiration is a major bioengineering target for increasing crop yields as it is often considered a wasteful process. Photorespiratory metabolism is integrated into leaf metabolism and thus may have certain benefits. Here, we show that plants can increase their rate of photosynthetic CO2 uptake when assimilating nitrogen de novo via the photorespiratory pathway by fixing carbon as amino acids in addition to carbohydrates. Plants fed NO3- had higher rates of CO2 assimilation under photorespiratory than low-photorespiratory conditions, while plants lacking NO3- nutrition exhibited lower stimulation of CO2 uptake. We modified the widely used Farquhar, von Caemmerer and Berry photosynthesis model to include the carbon and electron requirements for nitrogen assimilation via the photorespiratory pathway. Our modified model improves predictions of photosynthetic CO2 uptake and of rates of photosynthetic electron transport. The results highlight how photorespiration can improve photosynthetic performance despite reducing the efficiency of Rubisco carboxylation.
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Affiliation(s)
- Florian A Busch
- Research School of Biology and ARC Centre of Excellence for Translational Photosynthesis, Australian National University, Acton, Australian Capital Territory, Australia.
| | - Rowan F Sage
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
| | - Graham D Farquhar
- Research School of Biology and ARC Centre of Excellence for Translational Photosynthesis, Australian National University, Acton, Australian Capital Territory, Australia
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11
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Bacher A, Chen F, Eisenreich W. Decoding Biosynthetic Pathways in Plants by Pulse-Chase Strategies Using (13)CO₂ as a Universal Tracer †. Metabolites 2016; 6:E21. [PMID: 27429012 PMCID: PMC5041120 DOI: 10.3390/metabo6030021] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 07/03/2016] [Accepted: 07/04/2016] [Indexed: 01/14/2023] Open
Abstract
(13)CO₂ pulse-chase experiments monitored by high-resolution NMR spectroscopy and mass spectrometry can provide (13)C-isotopologue compositions in biosynthetic products. Experiments with a variety of plant species have documented that the isotopologue profiles generated with (13)CO₂ pulse-chase labeling are directly comparable to those that can be generated by the application of [U-(13)C₆]glucose to aseptically growing plants. However, the application of the (13)CO₂ labeling technology is not subject to the experimental limitations that one has to take into account for experiments with [U-(13)C₆]glucose and can be applied to plants growing under physiological conditions, even in the field. In practical terms, the results of biosynthetic studies with (13)CO₂ consist of the detection of pairs, triples and occasionally quadruples of (13)C atoms that have been jointly contributed to the target metabolite, at an abundance that is well above the stochastic occurrence of such multiples. Notably, the connectivities of jointly transferred (13)C multiples can have undergone modification by skeletal rearrangements that can be diagnosed from the isotopologue data. As shown by the examples presented in this review article, the approach turns out to be powerful in decoding the carbon topology of even complex biosynthetic pathways.
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Affiliation(s)
- Adelbert Bacher
- Lehrstuhl für Biochemie, Technische Universität München, 85748 Garching, Germany.
| | - Fan Chen
- Lehrstuhl für Biochemie, Technische Universität München, 85748 Garching, Germany.
| | - Wolfgang Eisenreich
- Lehrstuhl für Biochemie, Technische Universität München, 85748 Garching, Germany.
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12
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Abadie C, Boex-Fontvieille ERA, Carroll AJ, Tcherkez G. In vivo stoichiometry of photorespiratory metabolism. NATURE PLANTS 2016; 2:15220. [PMID: 27249192 DOI: 10.1038/nplants.2015.220] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 12/14/2015] [Indexed: 05/08/2023]
Abstract
Photorespiration is a major light-dependent metabolic pathway that consumes oxygen and produces carbon dioxide. In the metabolic step responsible for carbon dioxide production, two molecules of glycine (equivalent to two molecules of O2) are converted into one molecule of serine and one molecule of CO2. Here, we use quantitative isotopic techniques to determine the stoichiometry of this reaction in sunflower leaves, and thereby the O2/CO2 stoichiometry of photorespiration. We find that the effective O2/CO2 stoichiometric coefficient at the leaf level is very close to 2 under normal photorespiratory conditions, in line with expectations, but increases slightly at high rates of photorespiration. The net metabolic impact of this imbalance is likely to be modest.
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Affiliation(s)
- Cyril Abadie
- Research School of Biology, ANU College of Medicine, Biology and Environment, Australian National University, Canberra ACT 0200, Australia
| | - Edouard R A Boex-Fontvieille
- Laboratoire BVpam, EA3061, Université de Lyon/Saint-Etienne, 23 rue du Docteur Michelon, 42000 Saint-Etienne, France
| | - Adam J Carroll
- Research School of Biology, ANU College of Medicine, Biology and Environment, Australian National University, Canberra ACT 0200, Australia
| | - Guillaume Tcherkez
- Research School of Biology, ANU College of Medicine, Biology and Environment, Australian National University, Canberra ACT 0200, Australia
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13
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Bloemen J, Bauweraerts I, De Vos F, Vanhove C, Vandenberghe S, Boeckx P, Steppe K. Fate of xylem-transported 11C- and 13C-labeled CO2 in leaves of poplar. PHYSIOLOGIA PLANTARUM 2015; 153:555-64. [PMID: 25142926 DOI: 10.1111/ppl.12262] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 07/02/2014] [Indexed: 05/26/2023]
Abstract
In recent studies, assimilation of xylem-transported CO2 has gained considerable attention as a means of recycling respired CO2 in trees. However, we still lack a clear and detailed picture on the magnitude of xylem-transported CO2 assimilation, in particular within leaf tissues. To this end, detached poplar leaves (Populus × canadensis Moench 'Robusta') were allowed to take up a dissolved (13)CO2 label serving as a proxy of xylem-transported CO2 entering the leaf from the branch. The uptake rate of the (13)C was manipulated by altering the vapor pressure deficit (VPD) (0.84, 1.29 and 1.83 kPa). Highest tissue enrichments were observed under the highest VPD. Among tissues, highest enrichment was observed in the petiole and the veins, regardless of the VPD treatment. Analysis of non-labeled leaves showed that some (13)C diffused from the labeled leaves and was fixed in the mesophyll of the non-labeled leaves. However, (13)C leaf tissue enrichment analysis with elemental analysis coupled to isotope ratio mass spectrometry was limited in spatial resolution at the leaf tissue level. Therefore, (11)C-based CO2 labeling combined with positron autoradiography was used and showed a more detailed spatial distribution within a single tissue, in particular in secondary veins. Therefore, in addition to (13)C, (11) C-based autoradiography can be used to study the fate of xylem-transported CO2 at leaf level, allowing the acquisition of data at a yet unprecedented resolution.
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Affiliation(s)
- Jasper Bloemen
- Laboratory of Plant Ecology, Ghent University, 9000, Gent, Belgium
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14
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Allen DK, Bates PD, Tjellström H. Tracking the metabolic pulse of plant lipid production with isotopic labeling and flux analyses: Past, present and future. Prog Lipid Res 2015; 58:97-120. [PMID: 25773881 DOI: 10.1016/j.plipres.2015.02.002] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 01/30/2015] [Accepted: 02/11/2015] [Indexed: 11/25/2022]
Abstract
Metabolism is comprised of networks of chemical transformations, organized into integrated biochemical pathways that are the basis of cellular operation, and function to sustain life. Metabolism, and thus life, is not static. The rate of metabolites transitioning through biochemical pathways (i.e., flux) determines cellular phenotypes, and is constantly changing in response to genetic or environmental perturbations. Each change evokes a response in metabolic pathway flow, and the quantification of fluxes under varied conditions helps to elucidate major and minor routes, and regulatory aspects of metabolism. To measure fluxes requires experimental methods that assess the movements and transformations of metabolites without creating artifacts. Isotopic labeling fills this role and is a long-standing experimental approach to identify pathways and quantify their metabolic relevance in different tissues or under different conditions. The application of labeling techniques to plant science is however far from reaching it potential. In light of advances in genetics and molecular biology that provide a means to alter metabolism, and given recent improvements in instrumentation, computational tools and available isotopes, the use of isotopic labeling to probe metabolism is becoming more and more powerful. We review the principal analytical methods for isotopic labeling with a focus on seminal studies of pathways and fluxes in lipid metabolism and carbon partitioning through central metabolism. Central carbon metabolic steps are directly linked to lipid production by serving to generate the precursors for fatty acid biosynthesis and lipid assembly. Additionally some of the ideas for labeling techniques that may be most applicable for lipid metabolism in the future were originally developed to investigate other aspects of central metabolism. We conclude by describing recent advances that will play an important future role in quantifying flux and metabolic operation in plant tissues.
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Affiliation(s)
- Doug K Allen
- United States Department of Agriculture, Agricultural Research Service, 975 North Warson Road, St. Louis, MO 63132, United States; Donald Danforth Plant Science Center, 975 North Warson Road, St. Louis, MO 63132, United States.
| | - Philip D Bates
- Department of Chemistry and Biochemistry, University of Southern Mississippi, Hattiesburg, MS 39406, United States
| | - Henrik Tjellström
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824, United States; Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI 48824, United States
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15
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The design and performance of a portable handheld (11)CO2 delivery system. Appl Radiat Isot 2014; 94:338-343. [PMID: 25305526 DOI: 10.1016/j.apradiso.2014.09.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 09/10/2014] [Accepted: 09/12/2014] [Indexed: 11/22/2022]
Abstract
We constructed a hand-held device to efficiently trap [(11)C]CO2 from the cyclotron target, safely transport up to 3.7GBq (100mCi) doses to remote sites and release it without the need for a liquid cryogen. The system consists of a 180W furnace and a miniature molecular sieve trap (80-100mg; 80-100mesh 13×) placed inside a lead pig weighing 11.1kg. The overall [(11)C]CO2 delivery efficiency of the device is ~82% (> 99% trapping efficiency). Radiation dose rates measured at 30cm from the surface of the pig are <43.5µSv/h (5mR/h) up to 2.59GBq (70mCi).
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16
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Chen YJ, Huang X, Mahieu NG, Cho K, Schaefer J, Patti GJ. Differential incorporation of glucose into biomass during Warburg metabolism. Biochemistry 2014; 53:4755-7. [PMID: 25010499 PMCID: PMC4116146 DOI: 10.1021/bi500763u] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
It is well established that most cancer cells take up an increased amount of glucose relative to that taken up by normal differentiated cells. The majority of this glucose carbon is secreted from the cell as lactate. The fate of the remaining glucose carbon, however, has not been well-characterized. Here we apply a novel combination of metabolomic technologies to track uniformly labeled glucose in HeLa cancer cells. We provide a list of specific intracellular metabolites that become enriched after being labeled for 48 h and quantitate the fraction of consumed glucose that ends up in proteins, peptides, sugars/glycerol, and lipids.
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Affiliation(s)
- Ying-Jr Chen
- Departments of †Chemistry, ‡Genetics, and §Medicine, Washington University in St. Louis , St. Louis, Missouri 63130, United States
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17
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Abstract
Bacteria associate with surfaces and one another by elaborating an extracellular matrix to encapsulate cells, creating communities termed biofilms. Biofilms are beneficial in some ecological niches, but also contribute to the pathogenesis of serious and chronic infectious diseases. New approaches and quantitative measurements are needed to define the composition and architecture of bacterial biofilms to help drive the development of strategies to interfere with biofilm assembly. Solid-state NMR is uniquely suited to the examination of insoluble and complex macromolecular and whole-cell systems. This article highlights three examples that implement solid-state NMR to deliver insights into bacterial biofilm composition and changes in cell-wall composition as cells transition to the biofilm lifestyle. Most recently, solid-state NMR measurements provided a total accounting of the protein and polysaccharide components in the extracellular matrix of an E. coli biofilm and transform our qualitative descriptions of matrix composition into chemical parameters that permit quantitative comparisons among samples. We present additional data for whole biofilm samples (cells plus the extracellular matrix) that complement matrix-only analyses. The study of bacterial biofilms by solid-state NMR is an exciting avenue ripe with many opportunities and we close the article by articulating some outstanding questions and future directions in this area.
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Affiliation(s)
| | - Lynette Cegelski
- Department of Chemistry, Stanford University, CA 94305, United States
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18
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Misra JB. Integrated operation of the photorespiratory cycle and cytosolic metabolism in the modulation of primary nitrogen assimilation and export of organic N-transport compounds from leaves: a hypothesis. JOURNAL OF PLANT PHYSIOLOGY 2014; 171:319-328. [PMID: 24157314 DOI: 10.1016/j.jplph.2013.09.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 09/17/2013] [Accepted: 09/17/2013] [Indexed: 06/02/2023]
Abstract
Photorespiration is generally considered to be an essentially dissipative process, although it performs some protective and essential functions. A theoretical appraisal indicates that the loss of freshly assimilated CO2 due to photorespiration in well-watered plants may not be as high as generally believed. Even under moderately adverse conditions, these losses may not exceed 10%. The photorespiratory metabolism of the source leaves of well-watered and well-nourished crop plants ought to be different from that of other leaves because the fluxes of the export of both carbohydrates and organic N-transport compounds in source leaves is quite high. With a heuristic approach that involved the dovetailing of certain metabolic steps with the photorespiratory cycle (PR-cycle), a novel network is proposed to operate in the source-leaves of well-watered and well-nourished plants. This network allows for the diversion of metabolites from their cyclic-routes in sizeable quantities. With the removal of considerable quantities of glycine and serine from the cyclic route, the number of RuBP oxygenation events would be several times those of the formation of hydroxypyruvate. Thus, to an extreme extent, photorespiratory metabolism would become open-ended and involve much less futile recycling of glycine and serine. Conversion of glyoxylate to glycine has been proposed to be a crucial step in the determination of the relative rates of the futile (cyclic) and anabolic (open-ended) routes. Thus, in the source leaves of well-watered and well-nourished plants, the importance of the cyclic route is limited to the salvaging of photorespiratory intermediates for the regeneration of RuBP. The proposed network is resilient enough to coordinate the rates of the assimilation of carbon and nitrogen in accordance with the moisture and N-fertility statuses of the soil.
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Affiliation(s)
- Jitendra B Misra
- Directorate of Groundnut Research, Junagadh 362001, Gujarat, India.
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19
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Dirks RC, Singh M, Potter GS, Sobotka LG, Schaefer J. Glycine metabolism in leaves of Glycine max in 200 and 600-ppm CO2 environments. THE NEW PHYTOLOGIST 2013; 198:339-342. [PMID: 23437894 DOI: 10.1111/nph.12206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Affiliation(s)
- Rebecca C Dirks
- Department of Chemistry, Washington University, St Louis, MO, 63130, USA
| | - Manmilan Singh
- Department of Chemistry, Washington University, St Louis, MO, 63130, USA
| | - Gregory S Potter
- Department of Chemistry, Washington University, St Louis, MO, 63130, USA
| | - Lee G Sobotka
- Department of Chemistry, Washington University, St Louis, MO, 63130, USA
| | - Jacob Schaefer
- Department of Chemistry, Washington University, St Louis, MO, 63130, USA
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20
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Tcherkez G. Is the recovery of (photo) respiratory CO2 and intermediates minimal? THE NEW PHYTOLOGIST 2013; 198:334-338. [PMID: 23240660 DOI: 10.1111/nph.12101] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Affiliation(s)
- Guillaume Tcherkez
- Institute of Plant Biology, CNRS UMR 8618, Université Paris-Sud, 91405, Orsay Cedex, France
- Institut Universitaire de France, 103 Boulevard Saint-Michel, 75005, Paris, France
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