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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 Physiol 2016; 57:2020-2028. [PMID: 27497446 DOI: 10.1093/pcp/pcw127] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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Keerberg O, Pärnik T, Ivanova H, Bassüner B, Bauwe H. C2 photosynthesis generates about 3-fold elevated leaf CO2 levels in the C3-C4 intermediate species Flaveria pubescens. J Exp Bot 2014; 65:3649-56. [PMID: 24916069 PMCID: PMC4085972 DOI: 10.1093/jxb/eru239] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Formation of a photorespiration-based CO2-concentrating mechanism in C3-C4 intermediate plants is seen as a prerequisite for the evolution of C4 photosynthesis, but it is not known how efficient this mechanism is. Here, using in vivo Rubisco carboxylation-to-oxygenation ratios as a proxy to assess relative intraplastidial CO2 levels is suggested. Such ratios were determined for the C3-C4 intermediate species Flaveria pubescens compared with the closely related C3 plant F. cronquistii and the C4 plant F. trinervia. To this end, a model was developed to describe the major carbon fluxes and metabolite pools involved in photosynthetic-photorespiratory carbon metabolism and used quantitatively to evaluate the labelling kinetics during short-term (14)CO2 incorporation. Our data suggest that the photorespiratory CO2 pump elevates the intraplastidial CO2 concentration about 3-fold in leaves of the C3-C4 intermediate species F. pubescens relative to the C3 species F. cronquistii.
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Affiliation(s)
- Olav Keerberg
- Department of Plant Physiology, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, 51014 Tartu, Estonia
| | - Tiit Pärnik
- Department of Plant Physiology, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, 51014 Tartu, Estonia
| | - Hiie Ivanova
- Department of Plant Physiology, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, 51014 Tartu, Estonia
| | - Burgund Bassüner
- Center for Conservation and Sustainable Development, Missouri Botanical Garden, St. Louis, MO 63166-0299, USA
| | - Hermann Bauwe
- Department of Plant Physiology, University of Rostock, 18051 Rostock, Germany
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Mallmann J, Heckmann D, Bräutigam A, Lercher MJ, Weber APM, Westhoff P, Gowik U. The role of photorespiration during the evolution of C4 photosynthesis in the genus Flaveria. eLife 2014; 3:e02478. [PMID: 24935935 PMCID: PMC4103682 DOI: 10.7554/elife.02478] [Citation(s) in RCA: 136] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Accepted: 06/14/2014] [Indexed: 01/08/2023] Open
Abstract
C4 photosynthesis represents a most remarkable case of convergent evolution of a complex trait, which includes the reprogramming of the expression patterns of thousands of genes. Anatomical, physiological, and phylogenetic and analyses as well as computational modeling indicate that the establishment of a photorespiratory carbon pump (termed C2 photosynthesis) is a prerequisite for the evolution of C4. However, a mechanistic model explaining the tight connection between the evolution of C4 and C2 photosynthesis is currently lacking. Here we address this question through comparative transcriptomic and biochemical analyses of closely related C3, C3-C4, and C4 species, combined with Flux Balance Analysis constrained through a mechanistic model of carbon fixation. We show that C2 photosynthesis creates a misbalance in nitrogen metabolism between bundle sheath and mesophyll cells. Rebalancing nitrogen metabolism requires anaplerotic reactions that resemble at least parts of a basic C4 cycle. Our findings thus show how C2 photosynthesis represents a pre-adaptation for the C4 system, where the evolution of the C2 system establishes important C4 components as a side effect.
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Affiliation(s)
- Julia Mallmann
- Institute for Plant Molecular and Developmental Biology, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - David Heckmann
- Institute for Computer Science, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Andrea Bräutigam
- Institute of Plant Biochemistry, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Martin J Lercher
- Institute for Computer Science, Heinrich-Heine-Universität, Düsseldorf, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Andreas PM Weber
- Institute of Plant Biochemistry, Heinrich-Heine-Universität, Düsseldorf, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Peter Westhoff
- Institute for Plant Molecular and Developmental Biology, Heinrich-Heine-Universität, Düsseldorf, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Udo Gowik
- Institute for Plant Molecular and Developmental Biology, Heinrich-Heine-Universität, Düsseldorf, Germany
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Ubierna N, Sun W, Kramer DM, Cousins AB. The efficiency of C4 photosynthesis under low light conditions in Zea mays, Miscanthus x giganteus and Flaveria bidentis. Plant Cell Environ 2013; 36:365-81. [PMID: 22812384 DOI: 10.1111/j.1365-3040.2012.02579.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The efficiency of C(4) photosynthesis in Zea mays, Miscanthus x giganteus and Flaveria bidentis in response to light was determined using measurements of gas exchange, (13) CO(2) photosynthetic discrimination, metabolite pools and spectroscopic assays, with models of C(4) photosynthesis and leaf (13) CO(2) discrimination. Spectroscopic and metabolite assays suggested constant energy partitioning between the C(4) and C(3) cycles across photosynthetically active radiation (PAR). Leakiness (φ), modelled using C(4) light-limited photosynthesis equations (φ(mod)), matched values from the isotope method without simplifications (φ(is)) and increased slightly from high to low PAR in all species. However, simplifications of bundle-sheath [CO(2)] and respiratory fractionation lead to large overestimations of φ at low PAR with the isotope method. These species used different strategies to maintain similar φ. For example, Z. mays had large rates of the C(4) cycle and low bundle-sheath cells CO(2 ) conductance (g(bs)). While F. bidentis had larger g(bs) but lower respiration rates and M. giganteus had less C(4) cycle capacity but low g(bs), which resulted in similar φ. This demonstrates that low g(bs) is important for efficient C(4) photosynthesis but it is not the only factor determining φ. Additionally, these C(4) species are able to optimize photosynthesis and minimize φ over a range of PARs, including low light.
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Affiliation(s)
- Nerea Ubierna
- School of Biological Sciences, Molecular Plant Sciences, Washington State University, Pullman, WA 99164-4236, USA
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Ubierna N, Sun W, Cousins AB. The efficiency of C(4) photosynthesis under low light conditions: assumptions and calculations with CO(2) isotope discrimination. J Exp Bot 2011; 62:3119-34. [PMID: 21527629 DOI: 10.1093/jxb/err073] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Leakiness (Φ), the proportion of carbon fixed by phosphoenolpyruvate carboxylation that leaks out of the bundle-sheath cells, determines C(4) photosynthetic efficiency. Large increases in Φ have been described at low irradiance. The underlying mechanisms for this increase remain uncertain, but changes in photorespiration or the energy partitioning between the C(4) and C(3) cycles have been suggested. Additionally, values of Φ at low light could be magnified from assumptions made when comparing measured photosynthetic discrimination against (13)C (Δ) with the theoretical formulation for Δ. For example, several simplifications are often made when modelling Δ to predict Φ including: (i) negligible fractionation during photorespiration and dark respiration; (ii) infinite mesophyll conductance; and (iii) CO(2) inside bundle-sheath cells (C(s)) is much larger than values in mesophyll cells (C(m)). Theoretical models for C(4) photosynthesis and C(4) Δ were combined to evaluate how these simplifications affect calculations of Δ and Φ at different light intensities. It was demonstrated that the effects of photorespiratory fractionations and mesophyll conductance were negligible at low light. Respiratory fractionation was relevant only when the magnitude of the fractionation factor was artificially increased during measurements. The largest error in estimating Φ occurred when assuming C(s) was much larger than C(m) at low light levels, when bundle-sheath conductance was large (g(s)), or at low O(2) concentrations. Under these conditions, the simplified equation for Δ overestimated Φ, and compromised comparisons between species with different g(s), and comparisons across O(2) concentrations.
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Affiliation(s)
- Nerea Ubierna
- School of Biological Sciences, Molecular Plant Sciences, Washington State University, Pullman, WA 99164-4236, USA.
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