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Furbank R, Kelly S, von Caemmerer S. Photosynthesis and food security: the evolving story of C 4 rice. PHOTOSYNTHESIS RESEARCH 2023; 158:121-130. [PMID: 37067631 PMCID: PMC10108777 DOI: 10.1007/s11120-023-01014-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 03/15/2023] [Indexed: 06/19/2023]
Abstract
Traditional "Green Revolution" cereal breeding strategies to improve yield are now reaching a plateau in our principal global food crop rice. Photosynthesis has now become a major target of international consortia to increase yield potential. Synthetic biology is being used across multiple large projects to improve photosynthetic efficiency. This review follows the genesis and progress of one of the first of these consortia projects, now in its 13th year; the Bill and Melinda Gates funded C4 Rice Project. This project seeks to install the biochemical and anatomical attributes necessary to support C4 photosynthesis in the C3 crop rice. Here we address the advances made thus far in installing the biochemical pathway and some of the key targets yet to be reached.
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Affiliation(s)
- Robert Furbank
- Division of Plant Science, Centre of Excellence for Translational Photosynthesis, Research School of Biology, Australian National University, Acton, ACT, Australia.
| | - Steven Kelly
- Department of Plant Sciences, University of Oxford, Oxford, UK
| | - Susanne von Caemmerer
- Division of Plant Science, Centre of Excellence for Translational Photosynthesis, Research School of Biology, Australian National University, Acton, ACT, Australia
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von Caemmerer S. Updating the steady-state model of C4 photosynthesis. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:6003-6017. [PMID: 34173821 PMCID: PMC8411607 DOI: 10.1093/jxb/erab266] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 06/06/2021] [Indexed: 05/22/2023]
Abstract
C4 plants play a key role in world agriculture. For example, C4 crops such as maize and sorghum are major contributors to food production in both developed and developing countries, and the C4 grasses sugarcane, miscanthus, and switchgrass are major plant sources of bioenergy. In the challenge to manipulate and enhance C4 photosynthesis, steady-state models of leaf photosynthesis provide an important tool for gas exchange analysis and thought experiments that can explore photosynthetic pathway changes. Here a previous C4 photosynthetic model developed by von Caemmerer and Furbank has been updated with new kinetic parameterization and temperature dependencies added. The parameterization was derived from experiments on the C4 monocot, Setaria viridis, which for the first time provides a cohesive parameterization. Mesophyll conductance and its temperature dependence have also been included, as this is an important step in the quantitative correlation between the initial slope of the CO2 response curve of CO2 assimilation and in vitro phosphoenolpyruvate carboxylase activity. Furthermore, the equations for chloroplast electron transport have been updated to include cyclic electron transport flow, and equations have been added to calculate the electron transport rate from measured CO2 assimilation rates.
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Affiliation(s)
- Susanne von Caemmerer
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, The Australian National University, Acton, ACT 2601, Australia
- Correspondence:
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3
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von Caemmerer S. Updating the steady-state model of C4 photosynthesis. JOURNAL OF EXPERIMENTAL BOTANY 2021. [PMID: 34173821 DOI: 10.5061/dryad.zcrjdfnc3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
C4 plants play a key role in world agriculture. For example, C4 crops such as maize and sorghum are major contributors to food production in both developed and developing countries, and the C4 grasses sugarcane, miscanthus, and switchgrass are major plant sources of bioenergy. In the challenge to manipulate and enhance C4 photosynthesis, steady-state models of leaf photosynthesis provide an important tool for gas exchange analysis and thought experiments that can explore photosynthetic pathway changes. Here a previous C4 photosynthetic model developed by von Caemmerer and Furbank has been updated with new kinetic parameterization and temperature dependencies added. The parameterization was derived from experiments on the C4 monocot, Setaria viridis, which for the first time provides a cohesive parameterization. Mesophyll conductance and its temperature dependence have also been included, as this is an important step in the quantitative correlation between the initial slope of the CO2 response curve of CO2 assimilation and in vitro phosphoenolpyruvate carboxylase activity. Furthermore, the equations for chloroplast electron transport have been updated to include cyclic electron transport flow, and equations have been added to calculate the electron transport rate from measured CO2 assimilation rates.
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Affiliation(s)
- Susanne von Caemmerer
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, The Australian National University, Acton, ACT 2601, Australia
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4
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Callegari Ferrari R, Pires Bittencourt P, Yumi Nagumo P, Silva Oliveira W, Aurineide Rodrigues M, Hartwell J, Freschi L. Developing Portulaca oleracea as a model system for functional genomics analysis of C 4/CAM photosynthesis. FUNCTIONAL PLANT BIOLOGY : FPB 2021; 48:666-682. [PMID: 33256895 DOI: 10.1071/fp20202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Accepted: 10/20/2020] [Indexed: 06/12/2023]
Abstract
Previously regarded as an intriguing photosynthetic curiosity, the occurrence of C4 and Crassulacean acid metabolism (CAM) photosynthesis within a single organism has recently emerged as a source of information for future biotechnological use. Among C4/CAM facultative species, Portulaca oleracea L. has been used as a model for biochemical and gene expression analysis of C4/CAM under field and laboratory conditions. In the present work, we focussed on developing molecular tools to facilitate functional genomics studies in this species, from the optimisation of RNA isolation protocols to a method for stable genetic transformation. Eleven variations of RNA extraction procedures were tested and compared for RNA quantity and quality. Also, 7 sample sets comprising total RNA from hormonal and abiotic stress treatments, distinct plant organs, leaf developmental stages, and subspecies were used to select, among 12 reference genes, the most stable reference genes for RT-qPCR analysis of each experimental condition. Furthermore, different explant sources, Agrobacterium tumefaciens strains, and regeneration and antibiotic selection media were tested in various combinations to optimise a protocol for stable genetic transformation of P. oleracea. Altogether, we provide essential tools for functional gene analysis in the context of C4/CAM photosynthesis, including an efficient RNA isolation method, preferred reference genes for RT-qPCR normalisation for a range of experimental conditions, and a protocol to produce P. oleracea stable transformants using A. tumefaciens.
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Affiliation(s)
- Renata Callegari Ferrari
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, São Paulo 05508-090, Brasil
| | - Priscila Pires Bittencourt
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, São Paulo 05508-090, Brasil
| | - Paula Yumi Nagumo
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, São Paulo 05508-090, Brasil
| | - Willian Silva Oliveira
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, São Paulo 05508-090, Brasil
| | - Maria Aurineide Rodrigues
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, São Paulo 05508-090, Brasil
| | - James Hartwell
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, L69 7ZB, UK
| | - Luciano Freschi
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, São Paulo 05508-090, Brasil; and Corresponding author.
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5
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Ermakova M, Arrivault S, Giuliani R, Danila F, Alonso‐Cantabrana H, Vlad D, Ishihara H, Feil R, Guenther M, Borghi GL, Covshoff S, Ludwig M, Cousins AB, Langdale JA, Kelly S, Lunn JE, Stitt M, von Caemmerer S, Furbank RT. Installation of C 4 photosynthetic pathway enzymes in rice using a single construct. PLANT BIOTECHNOLOGY JOURNAL 2021; 19:575-588. [PMID: 33016576 PMCID: PMC7955876 DOI: 10.1111/pbi.13487] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 08/08/2020] [Accepted: 09/23/2020] [Indexed: 05/06/2023]
Abstract
Introduction of a C4 photosynthetic mechanism into C3 crops offers an opportunity to improve photosynthetic efficiency, biomass and yield in addition to potentially improving nitrogen and water use efficiency. To create a two-cell metabolic prototype for an NADP-malic enzyme type C4 rice, we transformed Oryza sativa spp. japonica cultivar Kitaake with a single construct containing the coding regions of carbonic anhydrase, phosphoenolpyruvate (PEP) carboxylase, NADP-malate dehydrogenase, pyruvate orthophosphate dikinase and NADP-malic enzyme from Zea mays, driven by cell-preferential promoters. Gene expression, protein accumulation and enzyme activity were confirmed for all five transgenes, and intercellular localization of proteins was analysed. 13 CO2 labelling demonstrated a 10-fold increase in flux though PEP carboxylase, exceeding the increase in measured in vitro enzyme activity, and estimated to be about 2% of the maize photosynthetic flux. Flux from malate via pyruvate to PEP remained low, commensurate with the low NADP-malic enzyme activity observed in the transgenic lines. Physiological perturbations were minor and RNA sequencing revealed no substantive effects of transgene expression on other endogenous rice transcripts associated with photosynthesis. These results provide promise that, with enhanced levels of the C4 proteins introduced thus far, a functional C4 pathway is achievable in rice.
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Affiliation(s)
- Maria Ermakova
- Australian Research Council Centre of Excellence for Translational PhotosynthesisDivision of Plant ScienceResearch School of BiologyThe Australian National UniversityActonACTAustralia
| | | | - Rita Giuliani
- School of Biological SciencesMolecular Plant SciencesWashington State UniversityPullmanWAUSA
| | - Florence Danila
- Australian Research Council Centre of Excellence for Translational PhotosynthesisDivision of Plant ScienceResearch School of BiologyThe Australian National UniversityActonACTAustralia
| | - Hugo Alonso‐Cantabrana
- Australian Research Council Centre of Excellence for Translational PhotosynthesisDivision of Plant ScienceResearch School of BiologyThe Australian National UniversityActonACTAustralia
- Grains Research and Development CorporationBartonACTAustralia
| | - Daniela Vlad
- Department of Plant SciencesUniversity of OxfordOxfordUK
| | - Hirofumi Ishihara
- Max Planck Institute of Molecular Plant PhysiologyPotsdam‐GolmGermany
| | - Regina Feil
- Max Planck Institute of Molecular Plant PhysiologyPotsdam‐GolmGermany
| | - Manuela Guenther
- Max Planck Institute of Molecular Plant PhysiologyPotsdam‐GolmGermany
| | - Gian Luca Borghi
- Max Planck Institute of Molecular Plant PhysiologyPotsdam‐GolmGermany
| | - Sarah Covshoff
- Department of Plant SciencesUniversity of CambridgeCambridgeUK
| | - Martha Ludwig
- School of Molecular SciencesThe University of Western AustraliaCrawleyWAAustralia
| | - Asaph B. Cousins
- School of Biological SciencesMolecular Plant SciencesWashington State UniversityPullmanWAUSA
| | | | - Steven Kelly
- Department of Plant SciencesUniversity of OxfordOxfordUK
| | - John E. Lunn
- Max Planck Institute of Molecular Plant PhysiologyPotsdam‐GolmGermany
| | - Mark Stitt
- Max Planck Institute of Molecular Plant PhysiologyPotsdam‐GolmGermany
| | - Susanne von Caemmerer
- Australian Research Council Centre of Excellence for Translational PhotosynthesisDivision of Plant ScienceResearch School of BiologyThe Australian National UniversityActonACTAustralia
| | - Robert T. Furbank
- Australian Research Council Centre of Excellence for Translational PhotosynthesisDivision of Plant ScienceResearch School of BiologyThe Australian National UniversityActonACTAustralia
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6
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Danila FR, Thakur V, Chatterjee J, Bala S, Coe RA, Acebron K, Furbank RT, von Caemmerer S, Quick WP. Bundle sheath suberisation is required for C 4 photosynthesis in a Setaria viridis mutant. Commun Biol 2021; 4:254. [PMID: 33637850 PMCID: PMC7910553 DOI: 10.1038/s42003-021-01772-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 02/01/2021] [Indexed: 02/05/2023] Open
Abstract
C4 photosynthesis provides an effective solution for overcoming the catalytic inefficiency of Rubisco. The pathway is characterised by a biochemical CO2 concentrating mechanism that operates across mesophyll and bundle sheath (BS) cells and relies on a gas tight BS compartment. A screen of a mutant population of Setaria viridis, an NADP-malic enzyme type C4 monocot, generated using N-nitroso-N-methylurea identified a mutant with an amino acid change in the gene coding region of the ABCG transporter, a step in the suberin synthesis pathway. Here, Nile red staining, TEM, and GC/MS confirmed the alteration in suberin deposition in the BS cell wall of the mutant. We show that this has disrupted the suberin lamellae of BS cell wall and increased BS conductance to CO2 diffusion more than two-fold in the mutant. Consequently, BS CO2 partial pressure is reduced and CO2 assimilation was impaired in the mutant. Our findings provide experimental evidence that a functional suberin lamellae is an essential anatomical feature for efficient C4 photosynthesis in NADP-ME plants like S. viridis and have implications for engineering strategies to ensure future food security.
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Affiliation(s)
- Florence R Danila
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, The Australian National University, Acton, ACT, Australia.
| | - Vivek Thakur
- Department of Systems and Computational Biology, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Jolly Chatterjee
- International Rice Research Institute, Los Baños, Laguna, Philippines
| | - Soumi Bala
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, The Australian National University, Acton, ACT, Australia
| | - Robert A Coe
- International Rice Research Institute, Los Baños, Laguna, Philippines
| | - Kelvin Acebron
- International Rice Research Institute, Los Baños, Laguna, Philippines
| | - Robert T Furbank
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, The Australian National University, Acton, ACT, Australia
| | - Susanne von Caemmerer
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, The Australian National University, Acton, ACT, Australia
| | - William Paul Quick
- International Rice Research Institute, Los Baños, Laguna, Philippines
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
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7
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Sonawane BV, Cousins AB. Mesophyll CO 2 conductance and leakiness are not responsive to short- and long-term soil water limitations in the C 4 plant Sorghum bicolor. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 103:1590-1602. [PMID: 32438487 DOI: 10.1111/tpj.14849] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 04/30/2020] [Accepted: 05/05/2020] [Indexed: 05/13/2023]
Abstract
Breeding economically important C4 crops for enhanced whole-plant water-use efficiency (WUEplant ) is needed for sustainable agriculture. WUEplant is a complex trait and an efficient phenotyping method that reports on components of WUEplant , such as intrinsic water-use efficiency (WUEi , the rate of leaf CO2 assimilation relative to water loss via stomatal conductance), is needed. In C4 plants, theoretical models suggest that leaf carbon isotope composition (δ13 C), when the efficiency of the CO2 -concentrating mechanism (leakiness, ϕ) remains constant, can be used to screen for WUEi . The limited information about how ϕ responds to water limitations confines the application of δ13 C for WUEi screening of C4 crops. The current research aimed to test the response of ϕ to short- or long-term moderate water limitations, and the relationship of δ13 C with WUEi and WUEplant , by addressing potential mesophyll CO2 conductance (gm ) and biochemical limitations in the C4 plant Sorghum bicolor. We demonstrate that gm and ϕ are not responsive to short- or long-term water limitations. Additionally, δ13 C was not correlated with gas-exchange estimates of WUEi under short- and long-term water limitations, but showed a significant negative relationship with WUEplant . The observed association between the δ13 C and WUEplant suggests an intrinsic link of δ13 C with WUEi in this C4 plant, and can potentially be used as a screening tool for WUEplant in sorghum.
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Affiliation(s)
- Balasaheb V Sonawane
- School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA
| | - Asaph B Cousins
- School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA
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8
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Alonso-Cantabrana H, Cousins AB, Danila F, Ryan T, Sharwood RE, von Caemmerer S, Furbank RT. Diffusion of CO 2 across the Mesophyll-Bundle Sheath Cell Interface in a C 4 Plant with Genetically Reduced PEP Carboxylase Activity. PLANT PHYSIOLOGY 2018; 178:72-81. [PMID: 30018172 PMCID: PMC6130029 DOI: 10.1104/pp.18.00618] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 07/10/2018] [Indexed: 05/22/2023]
Abstract
Phosphoenolpyruvate carboxylase (PEPC), localized to the cytosol of the mesophyll cell, catalyzes the first carboxylation step of the C4 photosynthetic pathway. Here, we used RNA interference to target the cytosolic photosynthetic PEPC isoform in Setaria viridis and isolated independent transformants with very low PEPC activities. These plants required high ambient CO2 concentrations for growth, consistent with the essential role of PEPC in C4 photosynthesis. The combination of estimating direct CO2 fixation by the bundle sheath using gas-exchange measurements and modeling C4 photosynthesis with low PEPC activity allowed the calculation of bundle sheath conductance to CO2 diffusion (gbs ) in the progeny of these plants. Measurements made at a range of temperatures suggested no or negligible effect of temperature on gbs depending on the technique used to calculate gbs Anatomical measurements revealed that plants with reduced PEPC activity had reduced cell wall thickness and increased plasmodesmata (PD) density at the mesophyll-bundle sheath (M-BS) cell interface, whereas we observed little difference in these parameters at the mesophyll-mesophyll cell interface. The increased PD density at the M-BS interface was largely driven by an increase in the number of PD pit fields (cluster of PDs) rather than an increase in PD per pit field or the size of pit fields. The correlation of gbs with bundle sheath surface area per leaf area and PD area per M-BS area showed that these parameters and cell wall thickness are important determinants of gbs It is intriguing to speculate that PD development is responsive to changes in C4 photosynthetic flux.
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Affiliation(s)
- Hugo Alonso-Cantabrana
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Acton, Australian Capital Territory 2601, Australia
| | - Asaph B Cousins
- School of Biological Sciences, Molecular Plant Sciences, Washington State University, Pullman, Washington 99164-4236
| | - Florence Danila
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Acton, Australian Capital Territory 2601, Australia
| | - Timothy Ryan
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Acton, Australian Capital Territory 2601, Australia
| | - Robert E Sharwood
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Acton, Australian Capital Territory 2601, Australia
| | - Susanne von Caemmerer
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Acton, Australian Capital Territory 2601, Australia
| | - Robert T Furbank
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Acton, Australian Capital Territory 2601, Australia
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Sonawane BV, Sharwood RE, Whitney S, Ghannoum O. Shade compromises the photosynthetic efficiency of NADP-ME less than that of PEP-CK and NAD-ME C4 grasses. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:3053-3068. [PMID: 29659931 PMCID: PMC5972597 DOI: 10.1093/jxb/ery129] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Accepted: 03/19/2018] [Indexed: 05/18/2023]
Abstract
The high energy cost and apparently low plasticity of C4 photosynthesis compared with C3 photosynthesis may limit the productivity and distribution of C4 plants in low light (LL) environments. C4 photosynthesis evolved numerous times, but it remains unclear how different biochemical subtypes perform under LL. We grew eight C4 grasses belonging to three biochemical subtypes [NADP-malic enzyme (NADP-ME), NAD-malic enzyme (NAD-ME), and phosphoenolpyruvate carboxykinase (PEP-CK)] under shade (16% sunlight) or control (full sunlight) conditions and measured their photosynthetic characteristics at both low and high light. We show for the first time that LL (during measurement or growth) compromised the CO2-concentrating mechanism (CCM) to a greater extent in NAD-ME than in PEP-CK or NADP-ME C4 grasses by virtue of a greater increase in carbon isotope discrimination (∆P) and bundle sheath CO2 leakiness (ϕ), and a greater reduction in photosynthetic quantum yield (Φmax). These responses were partly explained by changes in the ratios of phosphoenolpyruvate carboxylase (PEPC)/initial Rubisco activity and dark respiration/photosynthesis (Rd/A). Shade induced a greater photosynthetic acclimation in NAD-ME than in NADP-ME and PEP-CK species due to a greater Rubisco deactivation. Shade also reduced plant dry mass to a greater extent in NAD-ME and PEP-CK relative to NADP-ME grasses. In conclusion, LL compromised the co-ordination of the C4 and C3 cycles and, hence, the efficiency of the CCM to a greater extent in NAD-ME than in PEP-CK species, while CCM efficiency was less impacted by LL in NADP-ME species. Consequently, NADP-ME species are more efficient at LL, which could explain their agronomic and ecological dominance relative to other C4 grasses.
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Affiliation(s)
- Balasaheb V Sonawane
- ARC Centre of Excellence for Translational Photosynthesis and Hawkesbury Institute for the Environment, Western Sydney University, NSW, Australia
- School of Biological Sciences, Washington State University, Pullman, WA, USA
- Correspondence:
| | - Robert E Sharwood
- ARC Centre of Excellence for Translational Photosynthesis and Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Spencer Whitney
- ARC Centre of Excellence for Translational Photosynthesis and Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Oula Ghannoum
- ARC Centre of Excellence for Translational Photosynthesis and Hawkesbury Institute for the Environment, Western Sydney University, NSW, Australia
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Salesse C, Sharwood R, Sakamoto W, Stern D. The Rubisco Chaperone BSD2 May Regulate Chloroplast Coverage in Maize Bundle Sheath Cells. PLANT PHYSIOLOGY 2017; 175:1624-1633. [PMID: 29089394 PMCID: PMC5717744 DOI: 10.1104/pp.17.01346] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 10/27/2017] [Indexed: 05/04/2023]
Abstract
In maize (Zea mays), Bundle Sheath Defective2 (BSD2) plays an essential role in Rubisco biogenesis and is required for correct bundle sheath (BS) cell differentiation. Yet, BSD2 RNA and protein levels are similar in mesophyll (M) and BS chloroplasts, although Rubisco accumulates only in BS chloroplasts. This raises the possibility of additional BSD2 roles in cell development. To test this hypothesis, transgenic lines were created that overexpress and underexpress BSD2 in both BS and M cells, driven by the cell type-specific Rubisco Small Subunit (RBCS) or Phosphoenolpyruvate Carboxylase (PEPC) promoters or the ubiquitin promoter. Genetic crosses showed that each of the transgenes could complement Rubisco deficiency and seedling lethality conferred by the bsd2 mutation. This was unexpected, as RBCS-BSD2 lines lacked BSD2 in M chloroplasts and PEPC-BSD2 lines expressed half the wild-type BSD2 level in BS chloroplasts. We conclude that BSD2 does not play a vital role in M cells and that BS BSD2 is in excess of requirements for Rubisco accumulation. BSD2 levels did affect chloroplast coverage in BS cells. In PEPC-BSD2 lines, chloroplast coverage decreased 30% to 50%, whereas lines with increased BSD2 content exhibited a 25% increase. This suggests that BSD2 has an ancillary role in BS cells related to chloroplast size. Gas exchange showed decreased photosynthetic rates in PEPC-BSD2 lines despite restored Rubisco function, correlating with reduced chloroplast coverage and pointing to CO2 diffusion changes. Conversely, increased chloroplast coverage did not result in increased Rubisco abundance or photosynthetic rates. This suggests another limitation beyond chloroplast volume, most likely Rubisco biogenesis and/or turnover rates.
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Affiliation(s)
- Coralie Salesse
- Boyce Thompson Institute, Cornell University, Ithaca, New York 14853
| | - Robert Sharwood
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia
| | - Wataru Sakamoto
- Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama 710-0046, Japan
| | - David Stern
- Boyce Thompson Institute, Cornell University, Ithaca, New York 14853
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11
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Salesse C, Sharwood R, Sakamoto W, Stern D. The Rubisco Chaperone BSD2 May Regulate Chloroplast Coverage in Maize Bundle Sheath Cells. PLANT PHYSIOLOGY 2017. [PMID: 29089394 DOI: 10.1104/pp.17.0134] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
In maize (Zea mays), Bundle Sheath Defective2 (BSD2) plays an essential role in Rubisco biogenesis and is required for correct bundle sheath (BS) cell differentiation. Yet, BSD2 RNA and protein levels are similar in mesophyll (M) and BS chloroplasts, although Rubisco accumulates only in BS chloroplasts. This raises the possibility of additional BSD2 roles in cell development. To test this hypothesis, transgenic lines were created that overexpress and underexpress BSD2 in both BS and M cells, driven by the cell type-specific Rubisco Small Subunit (RBCS) or Phosphoenolpyruvate Carboxylase (PEPC) promoters or the ubiquitin promoter. Genetic crosses showed that each of the transgenes could complement Rubisco deficiency and seedling lethality conferred by the bsd2 mutation. This was unexpected, as RBCS-BSD2 lines lacked BSD2 in M chloroplasts and PEPC-BSD2 lines expressed half the wild-type BSD2 level in BS chloroplasts. We conclude that BSD2 does not play a vital role in M cells and that BS BSD2 is in excess of requirements for Rubisco accumulation. BSD2 levels did affect chloroplast coverage in BS cells. In PEPC-BSD2 lines, chloroplast coverage decreased 30% to 50%, whereas lines with increased BSD2 content exhibited a 25% increase. This suggests that BSD2 has an ancillary role in BS cells related to chloroplast size. Gas exchange showed decreased photosynthetic rates in PEPC-BSD2 lines despite restored Rubisco function, correlating with reduced chloroplast coverage and pointing to CO2 diffusion changes. Conversely, increased chloroplast coverage did not result in increased Rubisco abundance or photosynthetic rates. This suggests another limitation beyond chloroplast volume, most likely Rubisco biogenesis and/or turnover rates.
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Affiliation(s)
- Coralie Salesse
- Boyce Thompson Institute, Cornell University, Ithaca, New York 14853
| | - Robert Sharwood
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia
| | - Wataru Sakamoto
- Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama 710-0046, Japan
| | - David Stern
- Boyce Thompson Institute, Cornell University, Ithaca, New York 14853
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12
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Sonawane BV, Sharwood RE, von Caemmerer S, Whitney SM, Ghannoum O. Short-term thermal photosynthetic responses of C4 grasses are independent of the biochemical subtype. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:5583-5597. [PMID: 29045727 PMCID: PMC5853683 DOI: 10.1093/jxb/erx350] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 09/14/2017] [Indexed: 05/20/2023]
Abstract
C4 photosynthesis evolved independently many times, resulting in multiple biochemical pathways; however, little is known about how these different pathways respond to temperature. We investigated the photosynthetic responses of eight C4 grasses belonging to three biochemical subtypes (NADP-ME, PEP-CK, and NAD-ME) to four leaf temperatures (18, 25, 32, and 40 °C). We also explored whether the biochemical subtype influences the thermal responses of (i) in vitro PEPC (Vpmax) and Rubisco (Vcmax) maximal activities, (ii) initial slope (IS) and CO2-saturated rate (CSR) derived from the A-Ci curves, and (iii) CO2 leakage out of the bundle sheath estimated from carbon isotope discrimination. We focussed on leakiness and the two carboxylases because they determine the coordination of the CO2-concentrating mechanism and are important for parameterizing the semi-mechanistic C4 photosynthesis model. We found that the thermal responses of Vpmax and Vcmax, IS, CSR, and leakiness varied among the C4 species independently of the biochemical subtype. No correlation was observed between Vpmax and IS or between Vcmax and CSR; while the ratios Vpmax/Vcmax and IS/CSR did not correlate with leakiness among the C4 grasses. Determining mesophyll and bundle sheath conductances in diverse C4 grasses is required to further elucidate how C4 photosynthesis responds to temperature.
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Affiliation(s)
- Balasaheb V Sonawane
- ARC Centre of Excellence for Translational Photosynthesis and Hawkesbury Institute for the Environment, Western Sydney University, Richmond NSW, Australia
| | - Robert E Sharwood
- ARC Centre of Excellence for Translational Photosynthesis and Research School of Biology, Australian National University, Canberra ACT, Australia
| | - Susanne von Caemmerer
- ARC Centre of Excellence for Translational Photosynthesis and Research School of Biology, Australian National University, Canberra ACT, Australia
| | - Spencer M Whitney
- ARC Centre of Excellence for Translational Photosynthesis and Research School of Biology, Australian National University, Canberra ACT, Australia
| | - Oula Ghannoum
- ARC Centre of Excellence for Translational Photosynthesis and Hawkesbury Institute for the Environment, Western Sydney University, Richmond NSW, Australia
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13
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Osborn HL, Alonso-Cantabrana H, Sharwood RE, Covshoff S, Evans JR, Furbank RT, von Caemmerer S. Effects of reduced carbonic anhydrase activity on CO2 assimilation rates in Setaria viridis: a transgenic analysis. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:299-310. [PMID: 27702996 PMCID: PMC5853810 DOI: 10.1093/jxb/erw357] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 09/05/2016] [Indexed: 05/22/2023]
Abstract
In C4 species, the major β-carbonic anhydrase (β-CA) localized in the mesophyll cytosol catalyses the hydration of CO2 to HCO3-, which phosphoenolpyruvate carboxylase uses in the first step of C4 photosynthesis. To address the role of CA in C4 photosynthesis, we generated transgenic Setaria viridis depleted in β-CA. Independent lines were identified with as little as 13% of wild-type CA. No photosynthetic defect was observed in the transformed lines at ambient CO2 partial pressure (pCO2). At low pCO2, a strong correlation between CO2 assimilation rates and CA hydration rates was observed. C18O16O isotope discrimination was used to estimate the mesophyll conductance to CO2 diffusion from the intercellular air space to the mesophyll cytosol (gm) in control plants, which allowed us to calculate CA activities in the mesophyll cytosol (Cm). This revealed a strong relationship between the initial slope of the response of the CO2 assimilation rate to cytosolic pCO2 (ACm) and cytosolic CA activity. However, the relationship between the initial slope of the response of CO2 assimilation to intercellular pCO2 (ACi) and cytosolic CA activity was curvilinear. This indicated that in S. viridis, mesophyll conductance may be a contributing limiting factor alongside CA activity to CO2 assimilation rates at low pCO2.
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Affiliation(s)
- Hannah L Osborn
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, The Australian National University, Acton, ACT 2601, Australia
| | - Hugo Alonso-Cantabrana
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, The Australian National University, Acton, ACT 2601, Australia
| | - Robert E Sharwood
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, The Australian National University, Acton, ACT 2601, Australia
| | - Sarah Covshoff
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, UK
| | - John R Evans
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, The Australian National University, Acton, ACT 2601, Australia
| | - Robert T Furbank
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, The Australian National University, Acton, ACT 2601, Australia
| | - Susanne von Caemmerer
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, The Australian National University, Acton, ACT 2601, Australia
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14
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Gong XY, Schäufele R, Schnyder H. Bundle-sheath leakiness and intrinsic water use efficiency of a perennial C4 grass are increased at high vapour pressure deficit during growth. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:321-333. [PMID: 27864539 PMCID: PMC5853292 DOI: 10.1093/jxb/erw417] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 10/20/2016] [Indexed: 05/05/2023]
Abstract
Bundle-sheath leakiness (ϕ) is a key parameter of the CO2-concentrating mechanism of C4 photosynthesis and is related to leaf-level intrinsic water use efficiency (WUEi). This work studied short-term dynamic responses of ϕ to alterations of atmospheric CO2 concentration in Cleistogenes squarrosa, a perennial grass, grown at high (1.6 kPa) or low (0.6 kPa) vapour pressure deficit (VPD) combined with high or low N supply in controlled environment experiments. ϕ was determined by concurrent measurements of photosynthetic gas exchange and on-line carbon isotope discrimination, using a new protocol. Growth at high VPD led to an increase of ϕ by 0.13 and a concurrent increase of WUEi by 14%, with similar effects at both N levels. ϕ responded dynamically to intercellular CO2 concentration (C i), increasing with C i Across treatments, ϕ was negatively correlated to the ratio of CO2 saturated assimilation rate to carboxylation efficiency (a proxy of the relative activities of Rubisco and phosphoenolpyruvate carboxylase) indicating that the long-term environmental effect on ϕ was related to the balance between C3 and C4 cycles. Our study revealed considerable dynamic and long-term variation in ϕ of C. squarrosa, suggesting that ϕ should be determined when carbon isotope discrimination is used to assess WUEi Also, the data indicate a trade-off between WUEi and energetic efficiency in C. squarrosa.
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Affiliation(s)
- Xiao Ying Gong
- Lehrstuhl für Grünlandlehre, Technische Universität München, Alte Akademie 12, 85354 Freising, Germany
| | - Rudi Schäufele
- Lehrstuhl für Grünlandlehre, Technische Universität München, Alte Akademie 12, 85354 Freising, Germany
| | - Hans Schnyder
- Lehrstuhl für Grünlandlehre, Technische Universität München, Alte Akademie 12, 85354 Freising, Germany
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15
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Ishikawa N, Takabayashi A, Noguchi K, Tazoe Y, Yamamoto H, von Caemmerer S, Sato F, Endo T. NDH-Mediated Cyclic Electron Flow Around Photosystem I is Crucial for C4 Photosynthesis. PLANT & CELL PHYSIOLOGY 2016; 57:2020-2028. [PMID: 27497446 DOI: 10.1093/pcp/pcw127] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 07/12/2016] [Indexed: 05/23/2023]
Abstract
C4 photosynthesis exhibits efficient CO2 assimilation in ambient air by concentrating CO2 around ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) through a metabolic pathway called the C4 cycle. It has been suggested that cyclic electron flow (CEF) around PSI mediated by chloroplast NADH dehydrogenase-like complex (NDH), an alternative pathway of photosynthetic electron transport (PET), plays a crucial role in C4 photosynthesis, although the contribution of NDH-mediated CEF is small in C3 photosynthesis. Here, we generated NDH-suppressed transformants of a C4 plant, Flaveria bidentis, and showed that the NDH-suppressed plants grow poorly, especially under low-light conditions. CO2 assimilation rates were consistently decreased in the NDH-suppressed plants under low and medium light intensities. Measurements of non-photochemical quenching (NPQ) of Chl fluorescence, the oxidation state of the reaction center of PSI (P700) and the electrochromic shift (ECS) of pigment absorbance indicated that proton translocation across the thylakoid membrane is impaired in the NDH-suppressed plants. Since proton translocation across the thylakoid membrane induces ATP production, these results suggest that NDH-mediated CEF plays a role in the supply of ATP which is required for C4 photosynthesis. Such a role is more crucial when the light that is available for photosynthesis is limited and the energy production by PET becomes rate-determining for C4 photosynthesis. Our results demonstrate that the physiological contribution of NDH-mediated CEF is greater in C4 photosynthesis than in C3 photosynthesis, suggesting that the mechanism of PET in C4 photosynthesis has changed from that in C3 photosynthesis accompanying the changes in the mechanism of CO2 assimilation.
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Affiliation(s)
- Noriko Ishikawa
- Graduate School of Biostudies, Kyoto University, Kitashirakawa-Oiwakecho, Sakyoku, Kyoto, 606-8502 Japan
| | - Atsushi Takabayashi
- Graduate School of Biostudies, Kyoto University, Kitashirakawa-Oiwakecho, Sakyoku, Kyoto, 606-8502 Japan
- Present address: Institute of Low Temperature Science, Hokkaido University, Kita-19, Nishi-8, Kita-ku, Sapporo, 060-0819 Japan
| | - Ko Noguchi
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo, 192-0392 Japan
| | - Youshi Tazoe
- Graduate School of Biostudies, Kyoto University, Kitashirakawa-Oiwakecho, Sakyoku, Kyoto, 606-8502 Japan
- Present address: Graduate School of Agricultural Science, Tohoku University, 1-1, Amamiya-machi, Tsutsumidori, Aoba-ku, Sendai, 981-8555 Japan
| | - Hiroshi Yamamoto
- Department of Botany, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyoku, Kyoto, 606-8502 Japan
| | - Susanne von Caemmerer
- Research School of Biology, The Australian National University, Canberra, ACT, 0200, Australia
| | - Fumihiko Sato
- Graduate School of Biostudies, Kyoto University, Kitashirakawa-Oiwakecho, Sakyoku, Kyoto, 606-8502 Japan
| | - Tsuyoshi Endo
- Graduate School of Biostudies, Kyoto University, Kitashirakawa-Oiwakecho, Sakyoku, Kyoto, 606-8502 Japan
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16
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Friesen PC, Sage RF. Photosynthetic responses to chilling in a chilling-tolerant and chilling-sensitive Miscanthus hybrid. PLANT, CELL & ENVIRONMENT 2016; 39:1420-1431. [PMID: 26714623 DOI: 10.1111/pce.12699] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 11/13/2015] [Accepted: 12/16/2015] [Indexed: 06/05/2023]
Abstract
Miscanthus is a C4 perennial grass being developed for bioenergy production in temperate regions where chilling events are common. To evaluate chilling effects on Miscanthus, we assessed the processes controlling net CO2 assimilation rate (A) in Miscanthus x giganteus (M161) and a chilling-sensitive Miscanthus hybrid (M115) before and after a chilling treatment of 12/5 °C. The temperature response of A and maximum Rubisco activity in vitro were identical below 20 °C in chilled and unchilled M161, demonstrating Rubisco capacity limits or co-limits A at cooler temperatures. By contrast, A in M115 decreased at all measurement temperatures after growth at 12/5 °C. Rubisco activity in vitro declined in proportion to the reduction in A in chilled M115 plants, indicating Rubisco capacity is responsible in part for the decline in A. Pyruvate orthophosphate dikinase activities were also reduced by the chilling treatment when assayed at 28 °C, indicating this enzyme may also contribute to the reduction in A in M115. The maximum extractable activities of PEPCase and NADP-ME remained largely unchanged after chilling. The carboxylation efficiency of the C4 cycle was depressed in both genotypes to a similar extent after chilling. ΦP :ΦCO2 remained unchanged in both genotypes indicating the C3 and C4 cycles decline equivalently upon chilling.
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Affiliation(s)
- P C Friesen
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, M5S 3B2, Canada
| | - R F Sage
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, M5S 3B2, Canada
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17
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von Caemmerer S, Furbank RT. Strategies for improving C4 photosynthesis. CURRENT OPINION IN PLANT BIOLOGY 2016; 31:125-34. [PMID: 27127850 DOI: 10.1016/j.pbi.2016.04.003] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 04/05/2016] [Accepted: 04/06/2016] [Indexed: 05/22/2023]
Abstract
Recent activities to improve photosynthetic performance in crop plants has focused mainly on C3 photosynthesis where there are clear identified targets such as improving Rubisco kinetics, installation of a CO2 concentrating mechanism and alleviating limitations in chloroplast electron transport. Here we address strategies to improve photosynthetic performance in C4 plants, which utilize a CO2 concentrating mechanism, having evolved a complex blend of anatomy and biochemistry to achieve this. While the limitations to photosynthetic flux are not as well studied in C4 plants, work in transgenic Flaveria bidentis, a transformable model C4 dicot, and recent transcriptional analysis of leaves from diverse C4 plants, provides several gene candidates for improvement of carbon metabolism (such as pyruvate orthophosphate dikinase, phosphoenolpyruvate carboxylase and Rubisco) and for access of CO2 to phosphoenolpyruvate carboxylase in the mesophyll cells (such as carbonic anhydrase and CO2 porins). Chloroplast electron transport in C4 plants is shared between the two cell types, providing opportunities not only to alleviate limitations to flux through intersystem electron transport by targeting nuclear encoded proteins in the cytochrome (Cyt) b6/f complex, but in better sharing the harvesting of light energy between mesophyll and bundle sheath chloroplasts. Gene candidates for improvement of C4 photosynthesis could be utilized either through transgenic approaches or via mining natural allelic variation in sequenced populations of crop species.
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Affiliation(s)
- Susanne von Caemmerer
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Plant Science Division, Research School of Biology, The Australian National University, Acton, ACT 2601, Australia.
| | - Robert T Furbank
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Plant Science Division, Research School of Biology, The Australian National University, Acton, ACT 2601, Australia
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18
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Sharwood RE, Sonawane BV, Ghannoum O, Whitney SM. Improved analysis of C4 and C3 photosynthesis via refined in vitro assays of their carbon fixation biochemistry. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:3137-48. [PMID: 27122573 PMCID: PMC4867899 DOI: 10.1093/jxb/erw154] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Plants operating C3 and C4 photosynthetic pathways exhibit differences in leaf anatomy and photosynthetic carbon fixation biochemistry. Fully understanding this underpinning biochemical variation is requisite to identifying solutions for improving photosynthetic efficiency and growth. Here we refine assay methods for accurately measuring the carboxylase and decarboxylase activities in C3 and C4 plant soluble protein. We show that differences in plant extract preparation and assay conditions are required to measure NADP-malic enzyme and phosphoenolpyruvate carboxylase (pH 8, Mg(2+), 22 °C) and phosphoenolpyruvate carboxykinase (pH 7, >2mM Mn(2+), no Mg(2+)) maximal activities accurately. We validate how the omission of MgCl2 during leaf protein extraction, lengthy (>1min) centrifugation times, and the use of non-pure ribulose-1,5-bisphosphate (RuBP) significantly underestimate Rubisco activation status. We show how Rubisco activation status varies with leaf ontogeny and is generally lower in mature C4 monocot leaves (45-60% activation) relative to C3 monocots (55-90% activation). Consistent with their >3-fold lower Rubisco contents, full Rubisco activation in soluble protein from C4 leaves (<5min) was faster than in C3 plant samples (<10min), with addition of Rubisco activase not required for full activation. We conclude that Rubisco inactivation in illuminated leaves primarily stems from RuBP binding to non-carbamylated enzyme, a state readily reversible by dilution during cellular protein extraction.
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Affiliation(s)
- Robert E Sharwood
- ARC Centre of Excellence for Translational Photosynthesis, Research School of Biology, Australian National University, Canberra ACT 2601, Australia
| | - Balasaheb V Sonawane
- ARC Centre of Excellence for Translational Photosynthesis, Hawkesbury Institute for the Environment, Western Sydney University, Richmond NSW 2753, Australia
| | - Oula Ghannoum
- ARC Centre of Excellence for Translational Photosynthesis, Hawkesbury Institute for the Environment, Western Sydney University, Richmond NSW 2753, Australia
| | - Spencer M Whitney
- ARC Centre of Excellence for Translational Photosynthesis, Research School of Biology, Australian National University, Canberra ACT 2601, Australia
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19
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Bräutigam A, Gowik U. Photorespiration connects C 3and C 4photosynthesis. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:2953-62. [PMID: 26912798 DOI: 10.1093/jxb/erw056] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
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20
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Alonso-Cantabrana H, von Caemmerer S. Carbon isotope discrimination as a diagnostic tool for C4 photosynthesis in C3-C4 intermediate species. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:3109-21. [PMID: 26862154 PMCID: PMC4867892 DOI: 10.1093/jxb/erv555] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The presence and activity of the C4 cycle in C3-C4 intermediate species have proven difficult to analyze, especially when such activity is low. This study proposes a strategy to detect C4 activity and estimate its contribution to overall photosynthesis in intermediate plants, by using tunable diode laser absorption spectroscopy (TDLAS) coupled to gas exchange systems to simultaneously measure the CO2 responses of CO2 assimilation (A) and carbon isotope discrimination (Δ) under low O2 partial pressure. Mathematical models of C3-C4 photosynthesis and Δ are then fitted concurrently to both responses using the same set of constants. This strategy was applied to the intermediate species Flaveria floridana and F. brownii, and to F. pringlei and F. bidentis as C3 and C4 controls, respectively. Our results support the presence of a functional C4 cycle in F. floridana, that can fix 12-21% of carbon. In F. brownii, 75-100% of carbon is fixed via the C4 cycle, and the contribution of mesophyll Rubisco to overall carbon assimilation increases with CO2 partial pressure in both intermediate plants. Combined gas exchange and Δ measurement and modeling is a powerful diagnostic tool for C4 photosynthesis.
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Affiliation(s)
- Hugo Alonso-Cantabrana
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
| | - Susanne von Caemmerer
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
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21
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Pinto H, Powell JR, Sharwood RE, Tissue DT, Ghannoum O. Variations in nitrogen use efficiency reflect the biochemical subtype while variations in water use efficiency reflect the evolutionary lineage of C4 grasses at inter-glacial CO2. PLANT, CELL & ENVIRONMENT 2016; 39:514-26. [PMID: 26381794 DOI: 10.1111/pce.12636] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 08/21/2015] [Accepted: 09/05/2015] [Indexed: 05/09/2023]
Abstract
C4 photosynthesis evolved multiple times in diverse lineages. Most physiological studies comparing C4 plants were not conducted at the low atmospheric CO2 prevailing during their evolution. Here, 24 C4 grasses belonging to three biochemical subtypes [nicotinamide adenine dinucleotide malic enzyme (NAD-ME), phosphoenolpyruvate carboxykinase (PCK) and nicotinamide adenine dinucleotide phosphate malic enzyme (NADP-ME)] and six major evolutionary lineages were grown under ambient (400 μL L(-1) ) and inter-glacial (280 μL L(-1) ) CO2 . We hypothesized that nitrogen-related and water-related physiological traits are associated with subtypes and lineages, respectively. Photosynthetic rate and stomatal conductance were constrained by the shared lineage, while variation in leaf mass per area (LMA), leaf N per area, plant dry mass and plant water use efficiency were influenced by the subtype. Subtype and lineage were equally important for explaining variations in photosynthetic nitrogen use efficiency (PNUE) and photosynthetic water use efficiency (PWUE). CO2 treatment impacted most parameters. Overall, higher LMA and leaf N distinguished the Chloridoideae/NAD-ME group, while NADP-ME and PCK grasses were distinguished by higher PNUE regardless of lineage. Plants were characterized by high photosynthesis and PWUE when grown at ambient CO2 and by high conductance at inter-glacial CO2 . In conclusion, the evolutionary and biochemical diversity among C4 grasses was aligned with discernible leaf physiology, but it remains unknown whether these traits represent ecophysiological adaptation.
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Affiliation(s)
- Harshini Pinto
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Jeff R Powell
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Robert E Sharwood
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
- Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia
| | - David T Tissue
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Oula Ghannoum
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
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22
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von Caemmerer S, Ghannoum O, Pengelly JJL, Cousins AB. Carbon isotope discrimination as a tool to explore C4 photosynthesis. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:3459-70. [PMID: 24711615 DOI: 10.1093/jxb/eru127] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Photosynthetic carbon isotope discrimination is a non-destructive tool for investigating C4 metabolism. Tuneable diode laser absorption spectroscopy provides new opportunities for making rapid, concurrent measurements of carbon isotope discrimination and CO2 assimilation over a range of environmental conditions, and this has facilitated the use of carbon isotope discrimination as a probe of C4 metabolism. In spite of the significant progress made in recent years, understanding how photosynthetic carbon isotope discrimination measured concurrently with gas exchange relates to carbon isotope composition of leaf and plant dry matter remains a challenge that requires resolution if this technique is to be successfully applied as a screening tool in crop breeding and phylogenetic research. In this review, we update our understanding of the factors and assumptions that underlie variations in photosynthetic carbon isotope discrimination in C4 leaves. Closing the main gaps in our understanding of carbon isotope discrimination during C4 photosynthesis may help advance research aimed at developing higher productivity and efficiency in key C4 food, feed, and biofuel crops.
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Affiliation(s)
- Susanne von Caemmerer
- Research School of Biology, The Australian National University, Canberra ACT 0200, Australia
| | - Oula Ghannoum
- Hawkesbury Institute for the Environment, University of Western Sydney, Hawkesbury campus, Locked Bag 1797, Penrith 2751, NSW, Australia
| | - Jasper J L Pengelly
- Research School of Biology, The Australian National University, Canberra ACT 0200, Australia
| | - Asaph B Cousins
- School of Biological Sciences, Washington State University, Pullman, WA 99164, USA
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23
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Pengelly JJL, Förster B, von Caemmerer S, Badger MR, Price GD, Whitney SM. Transplastomic integration of a cyanobacterial bicarbonate transporter into tobacco chloroplasts. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:3071-80. [PMID: 24965541 PMCID: PMC4071830 DOI: 10.1093/jxb/eru156] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Improving global yields of agricultural crops is a complex challenge with evidence indicating benefits in productivity are achieved by enhancing photosynthetic carbon assimilation. Towards improving rates of CO2 capture within leaf chloroplasts, this study shows the versatility of plastome transformation for expressing the Synechococcus PCC7002 BicA bicarbonate transporter within tobacco plastids. Fractionation of chloroplast membranes from transplastomic tob(BicA) lines showed that ~75% of the BicA localized to the thylakoid membranes and ~25% to the chloroplast envelope. BicA levels were highest in young emerging tob(BicA) leaves (0.12 μmol m(-2), ≈7mg m(-2)) accounting for ~0.1% (w/w) of the leaf protein. In these leaves, the molar amount of BicA was 16-fold lower than the abundant thylakoid photosystem II D1 protein (~1.9 μmol m(-2)) which was comparable to the 9:1 molar ratio of D1:BicA measured in air-grown Synechococcus PCC7002 cells. The BicA produced had no discernible effect on chloroplast ultrastructure, photosynthetic CO2-assimilation rates, carbon isotope discrimination, or growth of the tob(BicA) plants, implying that the bicarbonate transporter had little or no activity. These findings demonstrate the utility of plastome transformation for targeting bicarbonate transporter proteins into the chloroplast membranes without impeding growth or plastid ultrastructure. This study establishes the span of experimental measurements required to verify heterologous bicarbonate transporter function and location in chloroplasts and underscores the need for more detailed understanding of BicA structure and function to identify solutions for enabling its activation and operation in leaf chloroplasts.
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Affiliation(s)
- J J L Pengelly
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
| | - B Förster
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
| | - S von Caemmerer
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
| | - M R Badger
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
| | - G D Price
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
| | - S M Whitney
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
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24
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Pinto H, Sharwood RE, Tissue DT, Ghannoum O. Photosynthesis of C3, C3-C4, and C4 grasses at glacial CO2. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:3669-81. [PMID: 24723409 PMCID: PMC4085965 DOI: 10.1093/jxb/eru155] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Most physiology comparisons of C3 and C4 plants are made under current or elevated concentrations of atmospheric CO2 which do not reflect the low CO2 environment under which C4 photosynthesis has evolved. Accordingly, photosynthetic nitrogen (PNUE) and water (PWUE) use efficiency, and the activity of the photosynthetic carboxylases [Rubisco and phosphoenolpyruvate carboxylase (PEPC)] and decarboxylases [NADP-malic enzyme (NADP-ME) and phosphoenolpyruvate carboxykinase (PEP-CK)] were compared in eight C4 grasses with NAD-ME, PCK, and NADP-ME subtypes, one C3 grass, and one C3-C4 grass grown under ambient (400 μl l(-1)) and glacial (180 μl l(-1)) CO2. Glacial CO2 caused a smaller reduction of photosynthesis and a greater increase of stomatal conductance in C4 relative to C3 and C3-C4 species. Panicum bisulcatum (C3) acclimated to glacial [CO2] by doubling Rubisco activity, while Rubisco was unchanged in Panicum milioides (C3-C4), possibly due to its high leaf N and Rubisco contents. Glacial CO2 up-regulated Rubisco and PEPC activities in concert for several C4 grasses, while NADP-ME and PEP-CK activities were unchanged, reflecting the high control exerted by the carboxylases relative to the decarboxylases on the efficiency of C4 metabolism. Despite having larger stomatal conductance at glacial CO2, C4 species maintained greater PWUE and PNUE relative to C3-C4 and C3 species due to higher photosynthetic rates. Relative to other C4 subtypes, NAD-ME and PEP-CK grasses had the highest PWUE and PNUE, respectively; relative to C3, the C3-C4 grass had higher PWUE and similar PNUE at glacial CO2. Biomass accumulation was reduced by glacial CO2 in the C3 grass relative to the C3-C4 grass, while biomass was less reduced in NAD-ME grasses compared with NADP-ME and PCK grasses. Under glacial CO2, high resource use efficiency offers a key evolutionary advantage for the transition from C3 to C4 photosynthesis in water- and nutrient-limited environments.
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Affiliation(s)
- Harshini Pinto
- Hawkesbury Institute for the Environment, University of Western Sydney, Hawkesbury campus, Locked Bag 1797, Penrith 2751, NSW, Australia
| | - Robert E Sharwood
- Hawkesbury Institute for the Environment, University of Western Sydney, Hawkesbury campus, Locked Bag 1797, Penrith 2751, NSW, Australia
| | - David T Tissue
- Hawkesbury Institute for the Environment, University of Western Sydney, Hawkesbury campus, Locked Bag 1797, Penrith 2751, NSW, Australia
| | - Oula Ghannoum
- Hawkesbury Institute for the Environment, University of Western Sydney, Hawkesbury campus, Locked Bag 1797, Penrith 2751, NSW, Australia
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Sharwood RE, Sonawane BV, Ghannoum O. Photosynthetic flexibility in maize exposed to salinity and shade. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:3715-24. [PMID: 24692650 PMCID: PMC4085963 DOI: 10.1093/jxb/eru130] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
C4 photosynthesis involves a close collaboration of the C3 and C4 metabolic cycles across the mesophyll and bundle-sheath cells. This study investigated the coordination of C4 photosynthesis in maize plants subjected to two salinity (50 and 100mM NaCl) treatments and one shade (20% of full sunlight) treatment. Photosynthetic efficiency was probed by combining leaf gas-exchange measurements with carbon isotope discrimination and assaying the key carboxylases [ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and phosphoenolpyruvate carboxylase (PEPC)] and decarboxylases [nicotinamide adenine dinucleotide phosphate malic enzyme (NADP-ME) and phosphoenolpyruvate carboxykinase (PEP-CK)] operating in maize leaves. Generally, salinity inhibited plant growth and photosynthesis to a lesser extent than shade. Salinity reduced photosynthesis primarily by reducing stomatal conductance and secondarily by equally reducing Rubisco and PEPC activities; the decarboxylases were inhibited more than the carboxylases. Salinity increased photosynthetic carbon isotope discrimination (Δp) and reduced leaf dry-matter carbon isotope composition ((13)δ) due to changes in p i/p a (intercellular to ambient CO2 partial pressure), while CO2 leakiness out of the bundle sheath (ϕ) was similar to that in control plants. Acclimation to shade was underpinned by a greater downregulation of PEPC relative to Rubisco activity, and a lesser inhibition of NADP-ME (primary decarboxylase) relative to PEP-CK (secondary decarboxylase). Shade reduced Δp and ɸ without significantly affecting leaf (13)δ or p i/p a relative to control plants. Accordingly, shade perturbed the balance between the C3 and C4 cycles during photosynthesis in maize, and demonstrated the flexible partitioning of C4 acid decarboxylation activity between NADP-ME and PEP-CK in response to the environment. This study highlights the need to improve our understanding of the links between leaf (13)δ and photosynthetic Δp, and the role of the secondary decarboxylase PEP-CK in NADP-ME plants such as maize.
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Affiliation(s)
- Robert E Sharwood
- Hawkesbury Institute for the Environment, University of Western Sydney, Richmond, Locked bag 1797, Penrith NSW 2751, Australia
| | - Balasaheb V Sonawane
- Hawkesbury Institute for the Environment, University of Western Sydney, Richmond, Locked bag 1797, Penrith NSW 2751, Australia
| | - Oula Ghannoum
- Hawkesbury Institute for the Environment, University of Western Sydney, Richmond, Locked bag 1797, Penrith NSW 2751, Australia
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Wang Y, Long SP, Zhu XG. Elements required for an efficient NADP-malic enzyme type C4 photosynthesis. PLANT PHYSIOLOGY 2014; 164:2231-46. [PMID: 24521879 PMCID: PMC3982775 DOI: 10.1104/pp.113.230284] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 01/27/2014] [Indexed: 05/19/2023]
Abstract
C4 photosynthesis has higher light, nitrogen, and water use efficiencies than C3 photosynthesis. Although the basic anatomical, cellular, and biochemical features of C4 photosynthesis are well understood, the quantitative significance of each element of C4 photosynthesis to the high photosynthetic efficiency are not well defined. Here, we addressed this question by developing and using a systems model of C4 photosynthesis, which includes not only the Calvin-Benson cycle, starch synthesis, sucrose synthesis, C4 shuttle, and CO₂ leakage, but also photorespiration and metabolite transport between the bundle sheath cells and mesophyll cells. The model effectively simulated the CO₂ uptake rates, and the changes of metabolite concentrations under varied CO₂ and light levels. Analyses show that triose phosphate transport and CO₂ leakage can help maintain a high photosynthetic rate by balancing ATP and NADPH amounts in bundle sheath cells and mesophyll cells. Finally, we used the model to define the optimal enzyme properties and a blueprint for C4 engineering. As such, this model provides a theoretical framework for guiding C4 engineering and studying C4 photosynthesis in general.
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Affiliation(s)
- Yu Wang
- State Key Laboratory for Hybrid Rice and Key Laboratory of Computational Biology, CAS-MPG Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China (Y.W., X.-G.Z.)
- and Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (S.P.L.)
| | - Stephen P. Long
- State Key Laboratory for Hybrid Rice and Key Laboratory of Computational Biology, CAS-MPG Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China (Y.W., X.-G.Z.)
- and Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (S.P.L.)
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Sun W, Ubierna N, Ma JY, Walker BJ, Kramer DM, Cousins AB. The coordination of C4 photosynthesis and the CO2-concentrating mechanism in maize and Miscanthus x giganteus in response to transient changes in light quality. PLANT PHYSIOLOGY 2014; 164:1283-92. [PMID: 24488966 PMCID: PMC3938620 DOI: 10.1104/pp.113.224683] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 01/12/2014] [Indexed: 05/07/2023]
Abstract
Unequal absorption of photons between photosystems I and II, and between bundle-sheath and mesophyll cells, are likely to affect the efficiency of the CO2-concentrating mechanism in C4 plants. Under steady-state conditions, it is expected that the biochemical distribution of energy (ATP and NADPH) and photosynthetic metabolite concentrations will adjust to maintain the efficiency of C4 photosynthesis through the coordination of the C3 (Calvin-Benson-Bassham) and C4 (CO2 pump) cycles. However, under transient conditions, changes in light quality will likely alter the coordination of the C3 and C4 cycles, influencing rates of CO2 assimilation and decreasing the efficiency of the CO2-concentrating mechanism. To test these hypotheses, we measured leaf gas exchange, leaf discrimination, chlorophyll fluorescence, electrochromatic shift, photosynthetic metabolite pools, and chloroplast movement in maize (Zea mays) and Miscanthus × giganteus following transitional changes in light quality. In both species, the rate of net CO2 assimilation responded quickly to changes in light treatments, with lower rates of net CO2 assimilation under blue light compared with red, green, and blue light, red light, and green light. Under steady state, the efficiency of CO2-concentrating mechanisms was similar; however, transient changes affected the coordination of C3 and C4 cycles in M. giganteus but to a lesser extent in maize. The species differences in the ability to coordinate the activities of C3 and C4 cycles appear to be related to differences in the response of cyclic electron flux around photosystem I and potentially chloroplast rearrangement in response to changes in light quality.
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Affiliation(s)
- Wei Sun
- Institute of Grassland Science, Northeast Normal University, Key Laboratory of Vegetation Ecology, Ministry of Education, Changchun, Jilin 130024, China (W.S.)
- School of Biological Sciences, Molecular Plant Sciences, Washington State University, Pullman, Washington 99164 (W.S., N.U., B.J.W., A.B.C.)
- Key Laboratory of Biogeography and Bioresource in Arid Land, Chinese Academy of Sciences, Urumqi 830011, China (J.-Y.M.); and
- Biochemistry and Molecular Biology and Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824 (D.M.K.)
| | | | - Jian-Ying Ma
- Institute of Grassland Science, Northeast Normal University, Key Laboratory of Vegetation Ecology, Ministry of Education, Changchun, Jilin 130024, China (W.S.)
- School of Biological Sciences, Molecular Plant Sciences, Washington State University, Pullman, Washington 99164 (W.S., N.U., B.J.W., A.B.C.)
- Key Laboratory of Biogeography and Bioresource in Arid Land, Chinese Academy of Sciences, Urumqi 830011, China (J.-Y.M.); and
- Biochemistry and Molecular Biology and Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824 (D.M.K.)
| | - Berkley J. Walker
- Institute of Grassland Science, Northeast Normal University, Key Laboratory of Vegetation Ecology, Ministry of Education, Changchun, Jilin 130024, China (W.S.)
- School of Biological Sciences, Molecular Plant Sciences, Washington State University, Pullman, Washington 99164 (W.S., N.U., B.J.W., A.B.C.)
- Key Laboratory of Biogeography and Bioresource in Arid Land, Chinese Academy of Sciences, Urumqi 830011, China (J.-Y.M.); and
- Biochemistry and Molecular Biology and Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824 (D.M.K.)
| | - David M. Kramer
- Institute of Grassland Science, Northeast Normal University, Key Laboratory of Vegetation Ecology, Ministry of Education, Changchun, Jilin 130024, China (W.S.)
- School of Biological Sciences, Molecular Plant Sciences, Washington State University, Pullman, Washington 99164 (W.S., N.U., B.J.W., A.B.C.)
- Key Laboratory of Biogeography and Bioresource in Arid Land, Chinese Academy of Sciences, Urumqi 830011, China (J.-Y.M.); and
- Biochemistry and Molecular Biology and Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824 (D.M.K.)
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28
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Covshoff S, Burgess SJ, Kneřová J, Kümpers BMC. Getting the most out of natural variation in C4 photosynthesis. PHOTOSYNTHESIS RESEARCH 2014; 119:157-167. [PMID: 23794170 DOI: 10.1007/s11120-013-9872-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 06/12/2013] [Indexed: 06/02/2023]
Abstract
C4 photosynthesis is a complex trait that has a high degree of natural variation, involving anatomical and biochemical changes relative to the ancestral C3 state. It has evolved at least 66 times across a variety of lineages and the evolutionary route from C3 to C4 is likely conserved but not necessarily genetically identical. As such, a variety of C4 species are needed to identify what is fundamental to the C4 evolutionary process in a global context. In order to identify the genetic components of C4 form and function, a number of species are used as genetic models. These include Zea mays (maize), Sorghum bicolor (sorghum), Setaria viridis (Setaria), Flaveria bidentis, and Cleome gynandra. Each of these species has different benefits and challenges associated with its use as a model organism. Here, we propose that RNA profiling of a large sampling of C4, C3-C4, and C3 species, from as many lineages as possible, will allow identification of candidate genes necessary and sufficient to confer C4 anatomy and/or biochemistry. Furthermore, C4 model species will play a critical role in the functional characterization of these candidate genes and identification of their regulatory elements, by providing a platform for transformation and through the use of gene expression profiles in mesophyll and bundle sheath cells and along the leaf developmental gradient. Efforts should be made to sequence the genomes of F. bidentis and C. gynandra and to develop congeneric C3 species as genetic models for comparative studies. In combination, such resources would facilitate discovery of common and unique C4 regulatory mechanisms across genera.
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Affiliation(s)
- Sarah Covshoff
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK,
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29
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Yamori W, Hikosaka K, Way DA. Temperature response of photosynthesis in C3, C4, and CAM plants: temperature acclimation and temperature adaptation. PHOTOSYNTHESIS RESEARCH 2014; 119:101-17. [PMID: 23801171 DOI: 10.1007/s11120-013-9874-6] [Citation(s) in RCA: 385] [Impact Index Per Article: 38.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Accepted: 06/12/2013] [Indexed: 05/18/2023]
Abstract
Most plants show considerable capacity to adjust their photosynthetic characteristics to their growth temperatures (temperature acclimation). The most typical case is a shift in the optimum temperature for photosynthesis, which can maximize the photosynthetic rate at the growth temperature. These plastic adjustments can allow plants to photosynthesize more efficiently at their new growth temperatures. In this review article, we summarize the basic differences in photosynthetic reactions in C3, C4, and CAM plants. We review the current understanding of the temperature responses of C3, C4, and CAM photosynthesis, and then discuss the underlying physiological and biochemical mechanisms for temperature acclimation of photosynthesis in each photosynthetic type. Finally, we use the published data to evaluate the extent of photosynthetic temperature acclimation in higher plants, and analyze which plant groups (i.e., photosynthetic types and functional types) have a greater inherent ability for photosynthetic acclimation to temperature than others, since there have been reported interspecific variations in this ability. We found that the inherent ability for temperature acclimation of photosynthesis was different: (1) among C3, C4, and CAM species; and (2) among functional types within C3 plants. C3 plants generally had a greater ability for temperature acclimation of photosynthesis across a broad temperature range, CAM plants acclimated day and night photosynthetic process differentially to temperature, and C4 plants was adapted to warm environments. Moreover, within C3 species, evergreen woody plants and perennial herbaceous plants showed greater temperature homeostasis of photosynthesis (i.e., the photosynthetic rate at high-growth temperature divided by that at low-growth temperature was close to 1.0) than deciduous woody plants and annual herbaceous plants, indicating that photosynthetic acclimation would be particularly important in perennial, long-lived species that would experience a rise in growing season temperatures over their lifespan. Interestingly, across growth temperatures, the extent of temperature homeostasis of photosynthesis was maintained irrespective of the extent of the change in the optimum temperature for photosynthesis (T opt), indicating that some plants achieve greater photosynthesis at the growth temperature by shifting T opt, whereas others can also achieve greater photosynthesis at the growth temperature by changing the shape of the photosynthesis-temperature curve without shifting T opt. It is considered that these differences in the inherent stability of temperature acclimation of photosynthesis would be reflected by differences in the limiting steps of photosynthetic rate.
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Affiliation(s)
- Wataru Yamori
- Center for Environment, Health and Field Sciences, Chiba University, Kashiwa-no-ha 6-2-1, Kashiwa, Chiba, 277-0882, Japan,
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30
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von Caemmerer S. Steady-state models of photosynthesis. PLANT, CELL & ENVIRONMENT 2013; 36:1617-30. [PMID: 23496792 DOI: 10.1111/pce.12098] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 03/07/2013] [Accepted: 03/12/2013] [Indexed: 05/19/2023]
Abstract
In the challenge to increase photosynthetic rate per leaf area mathematical models of photosynthesis can be used to help interpret gas exchange measurements made under different environmental conditions and predict underlying photosynthetic biochemistry. To do this successfully it is important to improve the modelling of temperature dependencies of CO₂ assimilation and gain better understanding of internal CO₂ diffusion limitations. Despite these shortcomings steady-state models of photosynthesis provide simple easy to use tools for thought experiments to explore photosynthetic pathway changes such as redirecting photorespiratory CO₂, inserting bicarbonate pumps into C₃ chloroplasts or inserting C₄ photosynthesis into rice. Here a number of models derived from the C₃ model by Farquhar, von Caemmerer and Berry are discussed and compared.
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Affiliation(s)
- Susanne von Caemmerer
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia.
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31
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Leegood RC. Strategies for engineering C(4) photosynthesis. JOURNAL OF PLANT PHYSIOLOGY 2013; 170:378-388. [PMID: 23245935 DOI: 10.1016/j.jplph.2012.10.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Revised: 10/30/2012] [Accepted: 10/30/2012] [Indexed: 06/01/2023]
Abstract
C(3) photosynthesis is an inefficient process, because the enzyme that lies at the heart of the Benson-Calvin cycle, ribulose 1,5-bisphosphate carboxylase-oxygenase (Rubisco) is itself a very inefficient enzyme. The oxygenase activity of Rubisco is an unavoidable side reaction that is a consequence of its reaction mechanism. The product of oxygenation, glycollate 2-P, has to be retrieved by photorespiration, a process which results in the loss of a quarter of the carbon that was originally present in glycollate 2-P. Photorespiration therefore reduces carbon gain. Purely in terms of carbon economy, there is, therefore, a strong selection pressure on plants to reduce the rate of photorespiration so as to increase carbon gain, but it also improves water- and nitrogen-use efficiency. Possibilities for the manipulation of plants to decrease the amount of photorespiration include the introduction of improved Rubisco from other species, reconfiguring photorespiration, or introducing carbon-concentrating mechanisms, such as inorganic carbon transporters, carboxysomes or pyrenoids, or engineering a full C(4) Kranz pathway using the existing evolutionary progression in C(3)-C(4) intermediates as a blueprint. Possible routes and progress to suppressing photorespiration by introducing C(4) photosynthesis in C(3) crop plants will be discussed, including whether single cell C(4) photosynthesis is feasible, how the evolution of C(3)-C(4) intermediates can be used as a blueprint for engineering C(4) photosynthesis, which pathway for the C(4) cycle might be introduced and the extent to which processes and structures in C(3) plant might require optimisation.
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Affiliation(s)
- Richard C Leegood
- Robert Hill Institute and Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
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Brutnell TP, Wang L, Swartwood K, Goldschmidt A, Jackson D, Zhu XG, Kellogg E, Van Eck J. Setaria viridis: a model for C4 photosynthesis. THE PLANT CELL 2010; 22:2537-2544. [PMID: 20693355 DOI: 10.1007/978-3-319-45105-3_17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
C(4) photosynthesis drives productivity in several major food crops and bioenergy grasses, including maize (Zea mays), sugarcane (Saccharum officinarum), sorghum (Sorghum bicolor), Miscanthus x giganteus, and switchgrass (Panicum virgatum). Gains in productivity associated with C(4) photosynthesis include improved water and nitrogen use efficiencies. Thus, engineering C(4) traits into C(3) crops is an attractive target for crop improvement. However, the lack of a small, rapid cycling genetic model system to study C(4) photosynthesis has limited progress in dissecting the regulatory networks underlying the C(4) syndrome. Setaria viridis is a member of the Panicoideae clade and is a close relative of several major feed, fuel, and bioenergy grasses. It is a true diploid with a relatively small genome of ~510 Mb. Its short stature, simple growth requirements, and rapid life cycle will greatly facilitate genetic studies of the C(4) grasses. Importantly, S. viridis uses an NADP-malic enzyme subtype C(4) photosynthetic system to fix carbon and therefore is a potentially powerful model system for dissecting C(4) photosynthesis. Here, we summarize some of the recent advances that promise greatly to accelerate the use of S. viridis as a genetic system. These include our recent successful efforts at regenerating plants from seed callus, establishing a transient transformation system, and developing stable transformation.
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Affiliation(s)
- Thomas P Brutnell
- Boyce Thompson Institute, Cornell University, Ithaca, New York 14853, USA.
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