1
|
Bangari MPS, Nataraja KN. Can endophytes minimize photosynthetic limitation? TRENDS IN PLANT SCIENCE 2024; 29:403-405. [PMID: 38155045 DOI: 10.1016/j.tplants.2023.12.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 11/09/2023] [Accepted: 12/05/2023] [Indexed: 12/30/2023]
Abstract
Recently, it has been proposed that the respiratory metabolism of endophytes leads to an increased internal concentration of CO2, which contributes to higher photosynthesis. We argue that endophytes contribute to improved photosynthetic efficiency and net carbon gains by minimizing photosynthetic limitations.
Collapse
Affiliation(s)
- Mayank Pratap Singh Bangari
- Plant Molecular Biology Laboratory, Department of Crop Physiology, University of Agricultural Sciences Bangalore, Gandhi Krishi Vigyana Kendra, Bengaluru, 560065, India
| | - Karaba N Nataraja
- Plant Molecular Biology Laboratory, Department of Crop Physiology, University of Agricultural Sciences Bangalore, Gandhi Krishi Vigyana Kendra, Bengaluru, 560065, India.
| |
Collapse
|
2
|
Shi M, Zhao L, Wang Y. Identification and Characterization of Genes Encoding the Hydroxypyruvate Reductases in Chlamydomonas Reveal Their Distinct Roles in Photorespiration. FRONTIERS IN PLANT SCIENCE 2021; 12:690296. [PMID: 34249060 PMCID: PMC8264790 DOI: 10.3389/fpls.2021.690296] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 05/31/2021] [Indexed: 06/13/2023]
Abstract
Photorespiration plays an important role in maintaining normal physiological metabolism in higher plants and other oxygenic organisms, such as algae. The unicellular eukaryotic organism Chlamydomonas is reported to have a photorespiration system different from that in higher plants, and only two out of nine genes encoding photorespiratory enzymes have been experimentally characterized. Hydroxypyruvate reductase (HPR), which is responsible for the conversion of hydroxypyruvate into glycerate, is poorly understood and not yet explored in Chlamydomonas. To identify the candidate genes encoding hydroxypyruvate reductases in Chlamydomonas (CrHPR) and uncover their elusive functions, we performed sequence comparison, enzyme activity measurement, subcellular localization, and analysis of knockout/knockdown strains. Together, we identify five proteins to be good candidates for CrHPRs, all of which are detected with the activity of hydroxypyruvate reductase. CrHPR1, a nicotinamide adenine dinucleotide (NADH)-dependent enzyme in mitochondria, may function as the major component of photorespiration. Its deletion causes severe photorespiratory defects. CrHPR2 takes part in the cytosolic bypass of photorespiration as the compensatory pathway of CrHPR1 for the reduction of hydroxypyruvate. CrHPR4, with NADH as the cofactor, may participate in photorespiration by acting as the chloroplastidial glyoxylate reductase in glycolate-quinone oxidoreductase system. Therefore, the results reveal that CrHPRs are far more complex than previously recognized and provide a greatly expanded knowledge base for studies to understand how CrHPRs perform their functions in photorespiration. These will facilitate both modification of photorespiration and genetic engineering for crop improvement by synthetic biology.
Collapse
Affiliation(s)
- Menglin Shi
- College of Life Sciences, Nankai University, Tianjin, China
| | - Lei Zhao
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
- National Center of Technology Innovation for Synthetic Biology, Tianjin, China
| | - Yong Wang
- College of Life Sciences, Nankai University, Tianjin, China
| |
Collapse
|
3
|
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.
Collapse
|
4
|
Timm S, Hagemann M. Photorespiration-how is it regulated and how does it regulate overall plant metabolism? JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:3955-3965. [PMID: 32274517 DOI: 10.1093/jxb/eraa183] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 04/08/2020] [Indexed: 05/03/2023]
Abstract
Under the current atmospheric conditions, oxygenic photosynthesis requires photorespiration to operate. In the presence of low CO2/O2 ratios, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) performs an oxygenase side reaction, leading to the formation of high amounts of 2-phosphoglycolate during illumination. Given that 2-phosphoglycolate is a potent inhibitor of photosynthetic carbon fixation, it must be immediately removed through photorespiration. The core photorespiratory cycle is orchestrated across three interacting subcellular compartments, namely chloroplasts, peroxisomes, and mitochondria, and thus cross-talks with a multitude of other cellular processes. Over the past years, the metabolic interaction of photorespiration and photosynthetic CO2 fixation has attracted major interest because research has demonstrated the enhancement of C3 photosynthesis and growth through the genetic manipulation of photorespiration. However, to optimize future engineering approaches, it is also essential to improve our current understanding of the regulatory mechanisms of photorespiration. Here, we summarize recent progress regarding the steps that control carbon flux in photorespiration, eventually involving regulatory proteins and metabolites. In this regard, both genetic engineering and the identification of various layers of regulation point to glycine decarboxylase as the key enzyme to regulate and adjust the photorespiratory carbon flow. Potential implications of the regulation of photorespiration for acclimation to environmental changes along with open questions are also discussed.
Collapse
Affiliation(s)
- Stefan Timm
- University of Rostock, Plant Physiology Department, Rostock, Germany
| | - Martin Hagemann
- University of Rostock, Plant Physiology Department, Rostock, Germany
| |
Collapse
|
5
|
Momayyezi M, McKown AD, Bell SCS, Guy RD. Emerging roles for carbonic anhydrase in mesophyll conductance and photosynthesis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 101:831-844. [PMID: 31816145 DOI: 10.1111/tpj.14638] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Revised: 11/17/2019] [Accepted: 11/25/2019] [Indexed: 05/24/2023]
Abstract
Carbonic anhydrase (CA) is an abundant protein in most photosynthesizing organisms and higher plants. This review paper considers the physiological importance of the more abundant CA isoforms in photosynthesis, through their effects on CO2 diffusion and other processes in photosynthetic organisms. In plants, CA has multiple isoforms in three different families (α, β and γ) and is mainly known to catalyze the CO2↔HCO3- equilibrium. This reversible conversion has a clear role in photosynthesis, primarily through sustaining the CO2 concentration at the site of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Despite showing the same major reaction mechanism, the three main CA families are evolutionarily distinct. For different CA isoforms, cellular localization and total gene expression as a function of developmental stage are predicted to determine the role of each family in relation to the net assimilation rate. Reaction-diffusion modeling and observational evidence support a role for CA activity in reducing resistance to CO2 diffusion inside mesophyll cells by facilitating CO2 transfer in both gas and liquid phases. In addition, physical and/or biochemical interactions between CAs and other membrane-bound compartments, for example aquaporins, are suggested to trigger a CO2 -sensing response by stomatal movement. In response to environmental stresses, changes in the expression level of CAs and/or stimulated deactivation of CAs may correspond with lower photosynthetic capacity. We suggest that further studies should focus on the dynamics of the relationship between the activity of CAs (with different subcellular localization, abundance and gene expression) and limitations due to CO2 diffusivity through the mesophyll and supply of CO2 to photosynthetic reactions.
Collapse
Affiliation(s)
- Mina Momayyezi
- Department of Forest and Conservation Sciences, Faculty of Forestry, University of British Columbia, Forest Sciences Centre, 2424 Main Mall, Vancouver, BC, V6T 1Z4, Canada
- Department of Viticulture and Enology, University of California, Davis, CA, 95616, USA
| | - Athena D McKown
- Department of Forest and Conservation Sciences, Faculty of Forestry, University of British Columbia, Forest Sciences Centre, 2424 Main Mall, Vancouver, BC, V6T 1Z4, Canada
| | - Shannon C S Bell
- Department of Forest and Conservation Sciences, Faculty of Forestry, University of British Columbia, Forest Sciences Centre, 2424 Main Mall, Vancouver, BC, V6T 1Z4, Canada
| | - Robert D Guy
- Department of Forest and Conservation Sciences, Faculty of Forestry, University of British Columbia, Forest Sciences Centre, 2424 Main Mall, Vancouver, BC, V6T 1Z4, Canada
| |
Collapse
|
6
|
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.
Collapse
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
| |
Collapse
|
7
|
Earles JM, Buckley TN, Brodersen CR, Busch FA, Cano FJ, Choat B, Evans JR, Farquhar GD, Harwood R, Huynh M, John GP, Miller ML, Rockwell FE, Sack L, Scoffoni C, Struik PC, Wu A, Yin X, Barbour MM. Embracing 3D Complexity in Leaf Carbon-Water Exchange. TRENDS IN PLANT SCIENCE 2019; 24:15-24. [PMID: 30309727 DOI: 10.1016/j.tplants.2018.09.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 09/06/2018] [Accepted: 09/11/2018] [Indexed: 06/08/2023]
Abstract
Leaves are a nexus for the exchange of water, carbon, and energy between terrestrial plants and the atmosphere. Research in recent decades has highlighted the critical importance of the underlying biophysical and anatomical determinants of CO2 and H2O transport, but a quantitative understanding of how detailed 3D leaf anatomy mediates within-leaf transport has been hindered by the lack of a consensus framework for analyzing or simulating transport and its spatial and temporal dynamics realistically, and by the difficulty of measuring within-leaf transport at the appropriate scales. We discuss how recent technological advancements now make a spatially explicit 3D leaf analysis possible, through new imaging and modeling tools that will allow us to address long-standing questions related to plant carbon-water exchange.
Collapse
Affiliation(s)
- J Mason Earles
- School of Forestry & Environmental Studies, Yale University, New Haven, CT 06511, USA; Equal contribution
| | - Thomas N Buckley
- Department of Plant Sciences, University of California Davis, CA 95916, USA; Equal contribution
| | - Craig R Brodersen
- School of Forestry & Environmental Studies, Yale University, New Haven, CT 06511, USA
| | - Florian A Busch
- Research School of Biology, Australian National University, Action, ACT 0200, Australia
| | - F Javier Cano
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW 2753, Australia
| | - Brendan Choat
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW 2753, Australia
| | - John R Evans
- Research School of Biology, Australian National University, Action, ACT 0200, Australia
| | - Graham D Farquhar
- Research School of Biology, Australian National University, Action, ACT 0200, Australia
| | | | - Minh Huynh
- University of Sydney, Sydney, NSW 2006, Australia
| | - Grace P John
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, CA 90095, USA
| | - Megan L Miller
- College of Natural Resources, University of Idaho, Moscow, ID 83844, USA
| | - Fulton E Rockwell
- Department of Organism and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Lawren Sack
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, CA 90095, USA
| | - Christine Scoffoni
- Department of Biological Sciences, California State University Los Angeles, CA 90032, USA
| | - Paul C Struik
- Department of Plant Sciences, Wageningen University, Centre for Crop Systems Analysis, 6700 AK Wageningen, The Netherlands
| | - Alex Wu
- Centre for Plant Science, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Xinyou Yin
- Department of Plant Sciences, Wageningen University, Centre for Crop Systems Analysis, 6700 AK Wageningen, The Netherlands
| | - Margaret M Barbour
- University of Sydney, Sydney, NSW 2006, Australia; www.sydney.edu.au/science/people/margaret.barbour.
| |
Collapse
|
8
|
Abadie C, Bathellier C, Tcherkez G. Carbon allocation to major metabolites in illuminated leaves is not just proportional to photosynthesis when gaseous conditions (CO 2 and O 2 ) vary. THE NEW PHYTOLOGIST 2018; 218:94-106. [PMID: 29344970 DOI: 10.1111/nph.14984] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 11/29/2017] [Indexed: 06/07/2023]
Abstract
In gas-exchange experiments, manipulating CO2 and O2 is commonly used to change the balance between carboxylation and oxygenation. Downstream metabolism (utilization of photosynthetic and photorespiratory products) may also be affected by gaseous conditions but this is not well documented. Here, we took advantage of sunflower as a model species, which accumulates chlorogenate in addition to sugars and amino acids (glutamate, alanine, glycine and serine). We performed isotopic labelling with 13 CO2 under different CO2 /O2 conditions, and determined 13 C contents to compute 13 C-allocation patterns and build-up rates. The 13 C content in major metabolites was not found to be a constant proportion of net fixed carbon but, rather, changed dramatically with CO2 and O2 . Alanine typically accumulated at low O2 (hypoxic response) while photorespiratory intermediates accumulated under ambient conditions and at high photorespiration, glycerate accumulation exceeding serine and glycine build-up. Chlorogenate synthesis was relatively more important under normal conditions and at high CO2 and its synthesis was driven by phosphoenolpyruvate de novo synthesis. These findings demonstrate that carbon allocation to metabolites other than photosynthetic end products is affected by gaseous conditions and therefore the photosynthetic yield of net nitrogen assimilation varies, being minimal at high CO2 and maximal at high O2 .
Collapse
Affiliation(s)
- Cyril Abadie
- Research School of Biology, College of Science, Australian National University, 2601, Canberra, ACT, Australia
| | - Camille Bathellier
- Research School of Biology, College of Science, Australian National University, 2601, Canberra, ACT, Australia
| | - Guillaume Tcherkez
- Research School of Biology, College of Science, Australian National University, 2601, Canberra, ACT, Australia
| |
Collapse
|
9
|
Flexas J, Cano FJ, Carriquí M, Coopman RE, Mizokami Y, Tholen D, Xiong D. CO2 Diffusion Inside Photosynthetic Organs. THE LEAF: A PLATFORM FOR PERFORMING PHOTOSYNTHESIS 2018. [DOI: 10.1007/978-3-319-93594-2_7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
10
|
Tcherkez G, Gauthier P, Buckley TN, Busch FA, Barbour MM, Bruhn D, Heskel MA, Gong XY, Crous KY, Griffin K, Way D, Turnbull M, Adams MA, Atkin OK, Farquhar GD, Cornic G. Leaf day respiration: low CO 2 flux but high significance for metabolism and carbon balance. THE NEW PHYTOLOGIST 2017; 216:986-1001. [PMID: 28967668 DOI: 10.1111/nph.14816] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 08/13/2017] [Indexed: 05/04/2023]
Abstract
Contents 986 I. 987 II. 987 III. 988 IV. 991 V. 992 VI. 995 VII. 997 VIII. 998 References 998 SUMMARY: It has been 75 yr since leaf respiratory metabolism in the light (day respiration) was identified as a low-flux metabolic pathway that accompanies photosynthesis. In principle, it provides carbon backbones for nitrogen assimilation and evolves CO2 and thus impacts on plant carbon and nitrogen balances. However, for a long time, uncertainties have remained as to whether techniques used to measure day respiratory efflux were valid and whether day respiration responded to environmental gaseous conditions. In the past few years, significant advances have been made using carbon isotopes, 'omics' analyses and surveys of respiration rates in mesocosms or ecosystems. There is substantial evidence that day respiration should be viewed as a highly dynamic metabolic pathway that interacts with photosynthesis and photorespiration and responds to atmospheric CO2 mole fraction. The view of leaf day respiration as a constant and/or negligible parameter of net carbon exchange is now outdated and it should now be regarded as a central actor of plant carbon-use efficiency.
Collapse
Affiliation(s)
- Guillaume Tcherkez
- Research School of Biology, College of Science, and ARC Center of Excellence for Translational Photosynthesis, Australian National University, Canberra, ACT, 2601, Australia
| | - Paul Gauthier
- Department of Geosciences, Princeton University, Princeton, NJ, 08540, USA
| | - Thomas N Buckley
- IA Watson Grains Research Centre, University of Sydney, 12656 Newell Hwy, Narrabri, NSW, 2390, Australia
| | - Florian A Busch
- Research School of Biology, College of Science, and ARC Center of Excellence for Translational Photosynthesis, Australian National University, Canberra, ACT, 2601, Australia
| | - Margaret M Barbour
- Centre for Carbon, Water and Food, University of Sydney, 380 Werombi Rd, Brownlow Hill, NSW, 2570, Australia
| | - Dan Bruhn
- Section of Biology and Environmental Science, Department of Chemistry and Bioscience, Aalborg University, 9220, Aalborg East, Denmark
| | - Mary A Heskel
- The Ecosystems Center, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA, 02543, USA
| | - Xiao Ying Gong
- Lehrstuhl für Grünlandlehre, Technische Universität München, Alte Akademie 12, 85354, Freising, Germany
| | - Kristine Y Crous
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Kevin Griffin
- Department of Ecology, Evolution and Environmental Biology (E3B), Columbia University, 1200 Amsterdam Avenue, New York, NY, 10027, USA
| | - Danielle Way
- Department of Biology, University of Western Ontario, London, ON, N6A 5B7, Canada
| | - Matthew Turnbull
- Centre for Integrative Ecology, School of Biological Sciences, University of Canterbury, PB 4800, Christchurch, New Zealand
| | - Mark A Adams
- Centre for Carbon, Water and Food, University of Sydney, 380 Werombi Rd, Brownlow Hill, NSW, 2570, Australia
| | - Owen K Atkin
- ARC Centre of Excellence in Plant Energy Biology, Division of Plant Science, Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia
| | - Graham D Farquhar
- Research School of Biology, College of Science, and ARC Center of Excellence for Translational Photosynthesis, Australian National University, Canberra, ACT, 2601, Australia
| | - Gabriel Cornic
- Ecologie Systématique Evolution, Université Paris-Sud, 91405, Orsay Cedex, France
| |
Collapse
|
11
|
Hagemann M, Bauwe H. Photorespiration and the potential to improve photosynthesis. Curr Opin Chem Biol 2016; 35:109-116. [PMID: 27693890 DOI: 10.1016/j.cbpa.2016.09.014] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 09/09/2016] [Accepted: 09/15/2016] [Indexed: 01/13/2023]
Abstract
The photorespiratory pathway, in short photorespiration, is an essential metabolite repair pathway that allows the photosynthetic CO2 fixation of plants to occur in the presence of oxygen. It is necessary because oxygen is a competing substrate of the CO2-fixing enzyme ribulose 1,5-bisphosphate carboxylase, forming 2-phosphoglycolate that negatively interferes with photosynthesis. Photorespiration very efficiently recycles 2-phosphoglycolate into 3-phosphoglycerate, which re-enters the Calvin-Benson cycle to drive sustainable photosynthesis. Photorespiration however requires extra energy and re-oxidises one quarter of the 2-phosphoglycolate carbon to CO2, lowering potential maximum rates of photosynthesis in most plants including food and energy crops. This review discusses natural and artificial strategies to reduce the undesired impact of air oxygen on photosynthesis and in turn plant growth.
Collapse
Affiliation(s)
- Martin Hagemann
- Universität Rostock, Institut für Biowissenschaften, Abteilung Pflanzenphysiologie, Albert-Einstein-Str. 3, D-18051 Rostock, Germany.
| | - Hermann Bauwe
- Universität Rostock, Institut für Biowissenschaften, Abteilung Pflanzenphysiologie, Albert-Einstein-Str. 3, D-18051 Rostock, Germany
| |
Collapse
|
12
|
Abstract
It is difficult to distinguish influx and efflux of inorganic C in photosynthesizing tissues; this article examines what is known and where there are gaps in knowledge. Irreversible decarboxylases produce CO2, and CO2 is the substrate/product of enzymes that act as carboxylases and decarboxylases. Some irreversible carboxylases use CO2; others use HCO3(-). The relative role of permeation through the lipid bilayer versus movement through CO2-selective membrane proteins in the downhill, non-energized, movement of CO2 is not clear. Passive permeation explains most CO2 entry, including terrestrial and aquatic organisms with C3 physiology and biochemistry, terrestrial C4 plants and all crassulacean acid metabolism (CAM) plants, as well as being part of some mechanisms of HCO3(-) use in CO2 concentrating mechanism (CCM) function, although further work is needed to test the mechanism in some cases. However, there is some evidence of active CO2 influx at the plasmalemma of algae. HCO3(-) active influx at the plasmalemma underlies all cyanobacterial and some algal CCMs. HCO3(-) can also enter some algal chloroplasts, probably as part of a CCM. The high intracellular CO2 and HCO3(-) pools consequent upon CCMs result in leakage involving CO2, and occasionally HCO3(-). Leakage from cyanobacterial and microalgal CCMs involves up to half, but sometimes more, of the gross inorganic C entering in the CCM; leakage from terrestrial C4 plants is lower in most environments. Little is known of leakage from other organisms with CCMs, though given the leakage better-examined organisms, leakage occurs and increases the energetic cost of net carbon assimilation.
Collapse
Affiliation(s)
- John A Raven
- Division of Plant Sciences, University of Dundee at the James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK†, and School of Plant Biology, University of Western Australia, M084, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - John Beardall
- School of Biological Sciences, Monash University, VIC 3800, Australia
| |
Collapse
|
13
|
Detecting long-term metabolic shifts using isotopomers: CO2-driven suppression of photorespiration in C3 plants over the 20th century. Proc Natl Acad Sci U S A 2015; 112:15585-90. [PMID: 26644588 DOI: 10.1073/pnas.1504493112] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Terrestrial vegetation currently absorbs approximately a third of anthropogenic CO2 emissions, mitigating the rise of atmospheric CO2. However, terrestrial net primary production is highly sensitive to atmospheric CO2 levels and associated climatic changes. In C3 plants, which dominate terrestrial vegetation, net photosynthesis depends on the ratio between photorespiration and gross photosynthesis. This metabolic flux ratio depends strongly on CO2 levels, but changes in this ratio over the past CO2 rise have not been analyzed experimentally. Combining CO2 manipulation experiments and deuterium NMR, we first establish that the intramolecular deuterium distribution (deuterium isotopomers) of photosynthetic C3 glucose contains a signal of the photorespiration/photosynthesis ratio. By tracing this isotopomer signal in herbarium samples of natural C3 vascular plant species, crops, and a Sphagnum moss species, we detect a consistent reduction in the photorespiration/photosynthesis ratio in response to the ∼100-ppm CO2 increase between ∼1900 and 2013. No difference was detected in the isotopomer trends between beet sugar samples covering the 20th century and CO2 manipulation experiments, suggesting that photosynthetic metabolism in sugar beet has not acclimated to increasing CO2 over >100 y. This provides observational evidence that the reduction of the photorespiration/photosynthesis ratio was ca. 25%. The Sphagnum results are consistent with the observed positive correlations between peat accumulation rates and photosynthetic rates over the Northern Hemisphere. Our results establish that isotopomers of plant archives contain metabolic information covering centuries. Our data provide direct quantitative information on the "CO2 fertilization" effect over decades, thus addressing a major uncertainty in Earth system models.
Collapse
|
14
|
Zhang Z, Mao X, Ou J, Ye N, Zhang J, Peng X. Distinct photorespiratory reactions are preferentially catalyzed by glutamate:glyoxylate and serine:glyoxylate aminotransferases in rice. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2015; 142:110-7. [DOI: 10.1016/j.jphotobiol.2014.11.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Revised: 11/14/2014] [Accepted: 11/18/2014] [Indexed: 01/09/2023]
|
15
|
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
| |
Collapse
|