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Bellasio C, Lundgren MR. The operation of PEPCK increases light harvesting plasticity in C 4 NAD-ME and NADP-ME photosynthetic subtypes: A theoretical study. PLANT, CELL & ENVIRONMENT 2024; 47:2288-2309. [PMID: 38494958 DOI: 10.1111/pce.14869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 02/15/2024] [Accepted: 02/18/2024] [Indexed: 03/19/2024]
Abstract
The repeated emergence of NADP-malic enzyme (ME), NAD-ME and phosphoenolpyruvate carboxykinase (PEPCK) subtypes of C4 photosynthesis are iconic examples of convergent evolution, which suggests that these biochemistries do not randomly assemble, but are instead specific adaptations resulting from unknown evolutionary drivers. Theoretical studies that are based on the classic biochemical understanding have repeatedly proposed light-use efficiency as a possible benefit of the PEPCK subtype. However, quantum yield measurements do not support this idea. We explore this inconsistency here via an analytical model that features explicit descriptions across a seamless gradient between C4 biochemistries to analyse light harvesting and dark photosynthetic metabolism. Our simulations show that the NADP-ME subtype, operated by the most productive crops, is the most efficient. The NAD-ME subtype has lower efficiency, but has greater light harvesting plasticity (the capacity to assimilate CO2 in the broadest combination of light intensity and spectral qualities). In both NADP-ME and NAD-ME backgrounds, increasing PEPCK activity corresponds to greater light harvesting plasticity but likely imposed a reduction in photosynthetic efficiency. We draw the first mechanistic links between light harvesting and C4 subtypes, providing the theoretical basis for future investigation.
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Affiliation(s)
- Chandra Bellasio
- Laboratory of Theoretical and Applied Crop Ecophysiology, School of Biology and Environmental Science, University College Dublin, Dublin, Ireland
- Department of Chemistry, Biology ond Biotechnology, Università Degli Studi Di Perugia, Perugia, Italy
- Department of Biology, University of the Balearic Islands, Palma, Illes Balears, Spain
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
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Ubierna N, Holloway-Phillips MM, Wingate L, Ogée J, Busch FA, Farquhar GD. Using Carbon Stable Isotopes to Study C 3 and C 4 Photosynthesis: Models and Calculations. Methods Mol Biol 2024; 2790:163-211. [PMID: 38649572 DOI: 10.1007/978-1-0716-3790-6_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
Stable carbon isotopes are a powerful tool to study photosynthesis. Initial applications consisted of determining isotope ratios of plant biomass using mass spectrometry. Subsequently, theoretical models relating C isotope values to gas exchange characteristics were introduced and tested against instantaneous online measurements of 13C photosynthetic discrimination. Beginning in the twenty-first century, laser absorption spectroscopes with sufficient precision for determining isotope mixing ratios became commercially available. This has allowed collection of large data sets at lower cost and with unprecedented temporal resolution. More data and accompanying knowledge have permitted refinement of 13C discrimination model equations, but often at the expense of increased model complexity and difficult parametrization. This chapter describes instantaneous online measurements of 13C photosynthetic discrimination, provides recommendations for experimental setup, and presents a thorough compilation of equations available to researchers. We update our previous 2018 version of this chapter by including recently improved descriptions of (photo)respiratory processes and associated fractionations. We discuss the capabilities and limitations of the diverse 13C discrimination model equations and provide guidance for selecting the model complexity needed for different applications.
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Affiliation(s)
- Nerea Ubierna
- Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement (INRAE), Unité Mixte de Recherche (UMR)1391 ISPA, Villenave D'Ornon, France
| | - Meisha-Marika Holloway-Phillips
- Research Unit of Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmendsorf, Switzerland
| | - Lisa Wingate
- Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement (INRAE), Unité Mixte de Recherche (UMR)1391 ISPA, Villenave D'Ornon, France
| | - Jérôme Ogée
- Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement (INRAE), Unité Mixte de Recherche (UMR)1391 ISPA, Villenave D'Ornon, France
| | - Florian A Busch
- School of Biosciences and The Birmingham Institute of Forest Research, University of Birmingham, Birmingham, UK
| | - Graham D Farquhar
- Research School of Biology, Australian National University, Canberra, ACT, Australia
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Chowdhury NB, Simons-Senftle M, Decouard B, Quillere I, Rigault M, Sajeevan KA, Acharya B, Chowdhury R, Hirel B, Dellagi A, Maranas C, Saha R. A multi-organ maize metabolic model connects temperature stress with energy production and reducing power generation. iScience 2023; 26:108400. [PMID: 38077131 PMCID: PMC10709110 DOI: 10.1016/j.isci.2023.108400] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 10/30/2023] [Accepted: 11/03/2023] [Indexed: 02/18/2024] Open
Abstract
Climate change has adversely affected maize productivity. Thereby, a holistic understanding of metabolic crosstalk among its organs is important to address this issue. Thus, we reconstructed the first multi-organ maize metabolic model, iZMA6517, and contextualized it with heat and cold stress transcriptomics data using expression distributed reaction flux measurement (EXTREAM) algorithm. Furthermore, implementing metabolic bottleneck analysis on contextualized models revealed differences between these stresses. While both stresses had reducing power bottlenecks, heat stress had additional energy generation bottlenecks. We also performed thermodynamic driving force analysis, revealing thermodynamics-reducing power-energy generation axis dictating the nature of temperature stress responses. Thus, a temperature-tolerant maize ideotype can be engineered by leveraging the proposed thermodynamics-reducing power-energy generation axis. We experimentally inoculated maize root with a beneficial mycorrhizal fungus, Rhizophagus irregularis, and as a proof-of-concept demonstrated its efficacy in alleviating temperature stress. Overall, this study will guide the engineering effort of temperature stress-tolerant maize ideotypes.
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Affiliation(s)
- Niaz Bahar Chowdhury
- Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, NE, USA
| | | | - Berengere Decouard
- Université Paris-Saclay, INRAE, AgroParisTech, Institut Jean-Pierre Bourgin (IJPB), 78000 Versailles, France
| | - Isabelle Quillere
- Université Paris-Saclay, INRAE, AgroParisTech, Institut Jean-Pierre Bourgin (IJPB), 78000 Versailles, France
| | - Martine Rigault
- Université Paris-Saclay, INRAE, AgroParisTech, Institut Jean-Pierre Bourgin (IJPB), 78000 Versailles, France
| | | | - Bibek Acharya
- Chemical and Biological Engineering, Iowa State University, Ames, IA, USA
| | - Ratul Chowdhury
- Chemical and Biological Engineering, Iowa State University, Ames, IA, USA
| | - Bertrand Hirel
- Centre de Versailles-Grignon, Institut National de Recherche pour l’Agriculture, Versailles, France
| | - Alia Dellagi
- Université Paris-Saclay, INRAE, AgroParisTech, Institut Jean-Pierre Bourgin (IJPB), 78000 Versailles, France
| | - Costas Maranas
- Chemical Engineering, The Pennsylvania State University, University Park, PA, USA
| | - Rajib Saha
- Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, NE, USA
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Sun H, Li W, Liang Y, Li G. Shading Stress at Different Grain Filling Stages Affects Dry Matter and Nitrogen Accumulation and Remobilization in Fresh Waxy Maize. PLANTS (BASEL, SWITZERLAND) 2023; 12:plants12091742. [PMID: 37176801 PMCID: PMC10180541 DOI: 10.3390/plants12091742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 04/14/2023] [Accepted: 04/21/2023] [Indexed: 05/15/2023]
Abstract
Shading stress caused by plum rain season, which overlapped with grain filling process of fresh waxy maize in Southern China, significantly affected crop productivity. In order to investigate the effects of shading at different stages after pollination on the yield, accumulation, and remobilization of dry matter and nitrogen (N) in fresh waxy maize, field experiments were conducted, including shading at 1-7 (Z1), 8-14 (Z2), 15-21 (Z3), and 1-21 (Z4) days after pollination in 2020 and 2021. The results showed that shading reduced the fresh ear and grain yield and increased moisture content in Suyunuo5 (SYN5) and Jingkenuo2000 (JKN2000) compared to natural lighting treatment (CK). The ear yield decrease was more severe in Z4 (43.5%), followed by Z1 (29.7%). Post-silking dry matter and N accumulation and remobilization were decreased under shading stress, and those were lowest in Z4, followed by Z1. The remobilization of pre-silking dry matter and N were increased by shading stress, and the increase was highest in Z4, followed by Z1. The harvest index of dry matter and N was lowest in Z4 and second-lowest in Z1. In conclusion, shading decreased yield by affecting accumulation and remobilization of post-silking dry matter and N, and the impact was more serious when it introduced early during grain filling stage in fresh waxy maize production.
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Affiliation(s)
- Haohan Sun
- Jiangsu Key Laboratory of Crop Genetics and Physiology, Yangzhou University, Yangzhou 225009, China
- Jiangsu Key Laboratory of Crop Cultivation and Physiology, Yangzhou University, Yangzhou 225009, China
| | - Wei Li
- Jiangsu Key Laboratory of Crop Genetics and Physiology, Yangzhou University, Yangzhou 225009, China
- Jiangsu Key Laboratory of Crop Cultivation and Physiology, Yangzhou University, Yangzhou 225009, China
| | - Yuwen Liang
- Jiangsu Key Laboratory of Crop Genetics and Physiology, Yangzhou University, Yangzhou 225009, China
- Jiangsu Key Laboratory of Crop Cultivation and Physiology, Yangzhou University, Yangzhou 225009, China
| | - Guanghao Li
- Jiangsu Key Laboratory of Crop Genetics and Physiology, Yangzhou University, Yangzhou 225009, China
- Jiangsu Key Laboratory of Crop Cultivation and Physiology, Yangzhou University, Yangzhou 225009, China
- Jiangsu Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou 225009, China
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Sagun JV, Chow WS, Ghannoum O. Leaf pigments and photosystems stoichiometry underpin photosynthetic efficiency of related C 3 , C-C 4 and C 4 grasses under shade. PHYSIOLOGIA PLANTARUM 2022; 174:e13819. [PMID: 36344438 DOI: 10.1111/ppl.13819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 09/12/2022] [Accepted: 10/31/2022] [Indexed: 06/16/2023]
Abstract
The quantum yield of photosynthesis (QY, CO2 fixed per light absorbed) depends on the efficiency of light absorption, the coupling between light absorption and electron transport, and the coupling between electron transport and carbon metabolism. QY is generally lower in C3 relative to C4 plants at warm temperatures and differs among the C4 subtypes. We investigated the acclimation to shade of light absorption and electron transport in six representative grasses with C3 , C3 -C4 and C4 photosynthesis. Plants were grown under full (control) or 25% (shade) sunlight. We measured the in vivo activity and stoichiometry of PSI and PSII, leaf spectral properties and pigment contents, and photosynthetic enzyme activities. Under control growth-light conditions, C4 species had higher CO2 assimilation rates, which declined to a greater extent relative to the C3 species. Whole leaf PSII/PSI ratios were highest in the C3 species, while QY and cyclic electron flow (CEF) were highest in the C4 , NADP-ME species. Shade significantly reduced leaf PSII/PSI, linear electron flow (LEF) and CEF of most species. Overall, shade reduced leaf absorptance, especially in the green region, as well as carotenoid and chlorophyll contents in C4 more than non-C4 species. The NAD-ME species underwent the greatest reduction in leaf absorptance and pigments under shade. In conclusion, shade compromised QY the least in the C3 and the most in the C4 -NAD-ME species. Different sensitivity to shade was associated with the ability to maintain leaf absorptance and pigments. This is important for maximising light absorption and minimising photoprotection under low light.
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Affiliation(s)
- Julius Ver Sagun
- ARC Centre of Excellence for Translational Photosynthesis, Hawkesbury Institute for the Environment, Western Sydney University, Penrith, Australia
| | - Wah Soon Chow
- ARC Centre of Excellence for Translational Photosynthesis, Research School of Biology, Australian National University, Canberra, Australia
| | - Oula Ghannoum
- ARC Centre of Excellence for Translational Photosynthesis, Hawkesbury Institute for the Environment, Western Sydney University, Penrith, Australia
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Bellasio C, Ermakova M. Reduction of bundle sheath size boosts cyclic electron flow in C 4 Setaria viridis acclimated to low light. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2022; 111:1223-1237. [PMID: 35866447 PMCID: PMC9545969 DOI: 10.1111/tpj.15915] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 06/29/2022] [Accepted: 07/07/2022] [Indexed: 05/22/2023]
Abstract
When C4 leaves are exposed to low light, the CO2 concentration in the bundle sheath (BS) cells decreases, causing an increase in photorespiration relative to assimilation, and a consequent reduction in biochemical efficiency. These effects can be mitigated by complex acclimation syndromes, which are of primary importance for crop productivity but are not well studied. We unveil an acclimation strategy involving the coordination of electron transport processes. First, we characterize the anatomy, gas exchange and electron transport of C4 Setaria viridis grown under low light. Through a purposely developed biochemical model, we resolve the photon fluxes and reaction rates to explain how the concerted acclimation strategies sustain photosynthetic efficiency. Our results show that a smaller BS in low-light-grown plants limited leakiness (the ratio of CO2 leak rate out of the BS over the rate of supply via C4 acid decarboxylation) but sacrificed light harvesting and ATP production. To counter ATP shortage and maintain high assimilation rates, plants facilitated light penetration through the mesophyll and upregulated cyclic electron flow in the BS. This shade tolerance mechanism, based on the optimization of light reactions, is possibly more efficient than the known mechanisms involving the rearrangement of carbon metabolism, and could potentially lead to innovative strategies for crop improvement.
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Affiliation(s)
- Chandra Bellasio
- Department of BiologyUniversity of the Balearic Islands07122PalmaIlles BalearsSpain
- Centre of Excellence for Translational Photosynthesis, Research School of BiologyThe Australian National UniversityActonACT2601Australia
| | - Maria Ermakova
- Centre of Excellence for Translational Photosynthesis, Research School of BiologyThe Australian National UniversityActonACT2601Australia
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Ramazan S, Bhat HA, Zargar MA, Ahmad P, John R. Combined gas exchange characteristics, chlorophyll fluorescence and response curves as selection traits for temperature tolerance in maize genotypes. PHOTOSYNTHESIS RESEARCH 2021; 150:213-225. [PMID: 33783665 DOI: 10.1007/s11120-021-00829-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 03/08/2021] [Indexed: 06/12/2023]
Abstract
Maize is a low-temperature (LT)-sensitive plant and its physiological responses towards LT of temperate regions developed is an adaptive trait. To further our understanding about the response of maize to LT at the physiological and photosynthesis level, we conducted Infrared Gas Analysis (IRGA using LICOR6400-XT in 45-day-old grown two maize genotypes, one from temperate region (Gurez-Kashmir Himalayas), viz., Gurez local (Gz local), and another from tropics (Gujarat), viz., GM6. This study was carried out to evaluate the underlying physiological mechanisms in the two differentially temperature-tolerant maize genotypes. Net photosynthetic rate (A/PN), 18.253 in Gz local and 25.587 (µmol CO2 m-2 s-1) in GM6; leaf conductance (gs), 0.0102 in Gz local and 0.0566 (mmol H2O m-2 s-1) in GM6; transpiration rate (E), 0.5371 in Gz local and 2.9409 (mmol H2O m-2 s-1) in GM6; and water use efficiency (WUE), 33.9852 in Gz local and 8.7224 (µmol CO2 mmol H2O-1) in GM6, were recorded under ambient conditions. Also, photochemical efficiency of photosystem II (PSII) (Fv/Fm), 0.675 in Gz local and 0.705 in GM6; maximum photochemical efficiency (Fv'/Fm'), 0.310234 in Gz local and 0.401391 in GM6; photochemical quenching (qP), 0.2375 in Gz local and 0.2609 in GM6; non-photochemical quenching (NPQ), 2.0036 in Gz local and 1.1686 in GM6; effective yield of PSII (ФPSII), 0.0789 in Gz local and 0.099 in GM6; and electron transport rate (ETR), 55.3152 in Gz local and 68.112 in GM6, were also evaluated in addition to various response curves, like light intensities and temperature. We observed that light response curves show the saturation light intensity requirement of 1600 µmol for both the genotypes, whereas temperature response curves showed the optimum temperature requirement for Gz local as 20 °C and for GM6 it was found to be 35 °C. The results obtained for each individual parameter and other correlational studies indicate that IRGA forms a promising route for quick and reliable screening of various stress-tolerant valuable genotypes, forming the first study of its kind.
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Affiliation(s)
- Salika Ramazan
- Plant Molecular Biology Lab, Department of Botany, University of Kashmir, Srinagar, Jammu and Kashmir, 190 006, India
| | - Hilal Ahmad Bhat
- Government Higher Secondary School, Kachwa-Muqam, Baramulla, Jammu and Kashmir, India
| | - Mohammad Arief Zargar
- Plant Physiology Laboratory, Department of Botany, University of Kashmir, Srinagar, Jammu and Kashmir, India
| | - Parvaiz Ahmad
- Department of Botany, S.P. College, Srinagar, Jammu and Kashmir, India
- Botany and Microbiology Department, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Riffat John
- Plant Molecular Biology Lab, Department of Botany, University of Kashmir, Srinagar, Jammu and Kashmir, 190 006, India.
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Zhou J, Tian L, Wang S, Li H, Zhao Y, Zhang M, Wang X, An P, Li C. Ovary Abortion Induced by Combined Waterlogging and Shading Stress at the Flowering Stage Involves Amino Acids and Flavonoid Metabolism in Maize. FRONTIERS IN PLANT SCIENCE 2021; 12:778717. [PMID: 34887895 PMCID: PMC8649655 DOI: 10.3389/fpls.2021.778717] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 11/01/2021] [Indexed: 05/26/2023]
Abstract
Maize (Zea mays L.) crops on the North China Plain are often subject to continuous overcast rain at the flowering stage. This causes waterlogging and shading stresses simultaneously and leads to huge yield losses, but the causes of these yield losses remain largely unknown. To explore the factors contributing to yield loss caused by combined waterlogging and shading stress at the flowering stage, we performed phenotypic, physiological, and quasi-targeted metabolomics analyses of maize plants subjected to waterlogging, shading, and combined waterlogging and shading (WS) treatments. Analyses of phenotypic and physiological indexes showed that, compared with waterlogging or shading alone, WS resulted in lower source strength, more severe inhibition of ovary and silk growth at the ear tip, a reduced number of emerged silks, and a higher rate of ovary abortion. Changes in carbon content and enzyme activity could not explain the ovary abortion in our study. Metabolomic analyses showed that the events occurred in ovaries and silks were closely related to abortion, WS forced the ovary to allocate more resources to the synthesis of amino acids involved in the stress response, inhibited the energy metabolism, glutathione metabolism and methionine salvage pathway, and overaccumulation of H2O2. In silks, WS led to lower accumulation levels of specific flavonoid metabolites with antioxidant capacity, and to over accumulation of H2O2. Thus, compared with each single stress, WS more seriously disrupted the normal metabolic process, and resulted more serious oxidative stress in ovaries and silks. Amino acids involved in the stress response in ovaries and specific flavonoid metabolites with antioxidant capacity in silks play important roles during ovary abortion. These results identify novel traits for selection in breeding programs and targets for genome editing to increase maize yield under WS stress.
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Torres R, Romero JM, Lagorio MG. Effects of sub-optimal illumination in plants. Comprehensive chlorophyll fluorescence analysis. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2021; 218:112182. [PMID: 33813366 DOI: 10.1016/j.jphotobiol.2021.112182] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 03/16/2021] [Accepted: 03/24/2021] [Indexed: 02/07/2023]
Abstract
The fluorescence signals emitted by chlorophyll molecules of plants is a promising non-destructive indicator of plant physiology due to its close link to photosynthesis. In this work, a deep photophysical study of chlorophyll fluorescence was provided, to assess the sub-optimal illumination effects on three plant species: L. sativa, A. hybridus and S. dendroideum. In all the cases, low light (LL) treatment induced an increase in pigment content. Fluorescence ratios - corrected by light reabsorption processes - remained constant, which suggested that photosystems stoichiometry was conserved. For all species and treatments, quantum yields of photophysical decay remained around 0.2, which meant that the maximum possible photosynthesis efficiency was about 0.8. L. sativa (C3) acclimated to low light illumination, displayed a strong increase in the LHC size and a net decrease in the photosynthetic efficiency. A. hybridus (C4) was not appreciably stressed by the low light availability whereas S. dendroideum (CAM), decreased its antenna and augmented the quantum yield of primary photochemistry. A novel approach to describe NPQ relaxation kinetics was also presented here and used to calculate typical deactivation times and amplitudes for NPQ components. LL acclimated L. sativa presented a much larger deactivation time for its state-transition-related quenching than the other species. Comprehensive fluorescence analysis allowed a deep study of the changes in the light-dependent reactions of photosynthesis upon low light illumination treatment.
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Affiliation(s)
- R Torres
- CONICET, Universidad de Buenos Aires, INQUIMAE, Facultad de Ciencias Exactas y Naturales, Buenos Aires, Argentina; Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Dpto. de Química Inorgánica, Analítica y Química Física, Ciudad Universitaria, Pabellón II, 1er piso, C1428EHA Buenos Aires, Argentina
| | - J M Romero
- CONICET, Universidad de Buenos Aires, INQUIMAE, Facultad de Ciencias Exactas y Naturales, Buenos Aires, Argentina; Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Dpto. de Química Inorgánica, Analítica y Química Física, Ciudad Universitaria, Pabellón II, 1er piso, C1428EHA Buenos Aires, Argentina
| | - M G Lagorio
- CONICET, Universidad de Buenos Aires, INQUIMAE, Facultad de Ciencias Exactas y Naturales, Buenos Aires, Argentina; Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Dpto. de Química Inorgánica, Analítica y Química Física, Ciudad Universitaria, Pabellón II, 1er piso, C1428EHA Buenos Aires, Argentina.
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Low Light/Darkness as Stressors of Multifactor-Induced Senescence in Rice Plants. Int J Mol Sci 2021; 22:ijms22083936. [PMID: 33920407 PMCID: PMC8069932 DOI: 10.3390/ijms22083936] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 04/06/2021] [Accepted: 04/08/2021] [Indexed: 12/11/2022] Open
Abstract
Leaf senescence, as an integral part of the final development stage for plants, primarily remobilizes nutrients from the sources to the sinks in response to different stressors. The premature senescence of leaves is a critical challenge that causes significant economic losses in terms of crop yields. Although low light causes losses of up to 50% and affects rice yield and quality, its regulatory mechanisms remain poorly elucidated. Darkness-mediated premature leaf senescence is a well-studied stressor. It initiates the expression of senescence-associated genes (SAGs), which have been implicated in chlorophyll breakdown and degradation. The molecular and biochemical regulatory mechanisms of premature leaf senescence show significant levels of redundant biomass in complex pathways. Thus, clarifying the regulatory mechanisms of low-light/dark-induced senescence may be conducive to developing strategies for rice crop improvement. This review describes the recent molecular regulatory mechanisms associated with low-light response and dark-induced senescence (DIS), and their effects on plastid signaling and photosynthesis-mediated processes, chloroplast and protein degradation, as well as hormonal and transcriptional regulation in rice.
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Ellsworth PZ, Feldman MJ, Baxter I, Cousins AB. A genetic link between leaf carbon isotope composition and whole-plant water use efficiency in the C 4 grass Setaria. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 102:1234-1248. [PMID: 31968138 DOI: 10.1111/tpj.14696] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 12/18/2019] [Accepted: 01/02/2020] [Indexed: 05/13/2023]
Abstract
Genetic selection for whole-plant water use efficiency (yield per transpiration; WUEplant ) in any crop-breeding programme requires high-throughput phenotyping of component traits of WUEplant such as intrinsic water use efficiency (WUEi ; CO2 assimilation rate per stomatal conductance). Measuring WUEi by gas exchange measurements is laborious and time consuming and may not reflect an integrated WUEi over the life of the leaf. Alternatively, leaf carbon stable isotope composition (δ13 Cleaf ) has been suggested as a potential time-integrated proxy for WUEi that may provide a tool to screen for WUEplant . However, a genetic link between δ13 Cleaf and WUEplant in a C4 species has not been well established. Therefore, to determine if there is a genetic relationship in a C4 plant between δ13 Cleaf and WUEplant under well watered and water-limited growth conditions, a high-throughput phenotyping facility was used to measure WUEplant in a recombinant inbred line (RIL) population created between the C4 grasses Setaria viridis and S. italica. Three quantitative trait loci (QTL) for δ13 Cleaf were found and co-localized with transpiration, biomass accumulation, and WUEplant . Additionally, WUEplant for each of the δ13 Cleaf QTL allele classes was negatively correlated with δ13 Cleaf , as would be predicted when WUEi influences WUEplant . These results demonstrate that δ13 Cleaf is genetically linked to WUEplant , likely to be through their relationship with WUEi , and can be used as a high-throughput proxy to screen for WUEplant in these C4 species.
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Affiliation(s)
- Patrick Z Ellsworth
- School of Biological Sciences, Washington State University, Pullman, WA, USA
| | - Max J Feldman
- Donald Danforth Plant Sciences Center, St. Louis, MO, USA
| | - Ivan Baxter
- Donald Danforth Plant Sciences Center, St. Louis, MO, USA
| | - Asaph B Cousins
- School of Biological Sciences, Washington State University, Pullman, WA, USA
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Serrano-Romero EA, Cousins AB. Cold acclimation of mesophyll conductance, bundle-sheath conductance and leakiness in Miscanthus × giganteus. THE NEW PHYTOLOGIST 2020; 226:1594-1606. [PMID: 32112409 DOI: 10.1111/nph.16503] [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: 08/20/2019] [Accepted: 02/16/2020] [Indexed: 06/10/2023]
Abstract
The cold acclimations of mesophyll conductance (gm ), bundle-sheath conductance (gbs ) and the CO2 concentrating mechanism (CCM) of C4 plants have not been well studied. Here, we estimated the temperature response of gm , gbs and leakiness (ϕ), the amount of concentrated CO2 that escapes the bundle-sheath cells, for the chilling-tolerant C4 plant Miscanthus × giganteus grown at 14 and 25°C. To estimate these parameters, we combined the C4 -enzyme-limited photosynthesis model and the Δ13 C discrimination model. These combined models were parameterised using in vitro activities of carbonic anhydrase (CA), pyruvate, phosphate dikinase (PPDK), ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), and phosphoenolpyruvate carboxylase (PEPc). Cold-grown Miscanthus plants increased in vitro activities of RuBisCO and PPDK but decreased PEPc activity compared with warm-grown plants. Mesophyll conductance and gbs responded strongly to measurement temperatures but did not differ between plants from the two growth temperatures. Furthermore, modelling showed that ϕ increased with measurement temperatures for both cold-grown and warm-grown plants, but was only marginally larger in cold-grown compared with warm-grown plants. Our results in Miscanthus support that gm and gbs are unresponsive to growth temperature and that the CCM is able to acclimate to cold through increased activity of PPDK and RuBisCO.
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Affiliation(s)
| | - Asaph B Cousins
- Molecular Plant Sciences, Washington State University, Pullman, WA, 99164-4236, USA
- School of Biological Sciences, Washington State University, Pullman, WA, 99164-4236, USA
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Yadav DS, Mishra AK, Rai R, Chaudhary N, Mukherjee A, Agrawal SB, Agrawal M. Responses of an old and a modern Indian wheat cultivar to future O 3 level: Physiological, yield and grain quality parameters. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 259:113939. [PMID: 32023796 DOI: 10.1016/j.envpol.2020.113939] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 12/13/2019] [Accepted: 01/07/2020] [Indexed: 06/10/2023]
Abstract
A field study was conducted to understand the physiological responses, yield and grain quality of an old (HUW234) and a modern (HD3118) wheat cultivar exposed to elevated ozone (O3). The cultivars were grown under ambient O3 (NF) and ambient +20 ppb O3 (NF+) conditions using open-top chambers (OTCs). The comparative study of an old and a modern cultivar showed variable physiological responses under elevated O3 exposure. Elevated O3 in old cultivar caused high reductions in Rubisco activity (Vcmax) and electron transport rate (J) compared to modern cultivar with simultaneous reductions in the rate of photosynthesis and chlorophyll fluorescence. In modern cultivar, high stomatal density and conductance caused higher O3 uptake thereby triggering more damage to the adjacent stomatal cells and photosynthetic pigments coupled with reductions in photosynthetic rate and photosynthetic nitrogen use efficiency (PNUE). Modern cultivar also showed relatively high reduction in grain yield compared to old one under NF + treatment. Furthermore, grain quality traits (such as starch, protein and amino acids) of modern cultivar were better than old cultivar under ambient O3, but showed more deterioration under NF + treatment. Results thus indicated that modern cultivar is relatively more susceptible to O3 and showed more negative impacts on plant performance, yield and quality of grains compared to old cultivar.
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Affiliation(s)
- Durgesh Singh Yadav
- Department of Botany, Institute of Science, Banaras Hindu University, Varanasi, India
| | - Amit Kumar Mishra
- Texas A&M AgriLife Research and Extension Center, Texas A&M University, Uvalde, TX 78801, USA
| | - Richa Rai
- Department of Botany, Institute of Science, Banaras Hindu University, Varanasi, India
| | - Nivedita Chaudhary
- Department of Botany, Institute of Science, Banaras Hindu University, Varanasi, India
| | - Arideep Mukherjee
- Department of Botany, Institute of Science, Banaras Hindu University, Varanasi, India
| | - S B Agrawal
- Department of Botany, Institute of Science, Banaras Hindu University, Varanasi, India
| | - Madhoolika Agrawal
- Department of Botany, Institute of Science, Banaras Hindu University, Varanasi, India.
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Watson-Lazowski A, Papanicolaou A, Koller F, Ghannoum O. The transcriptomic responses of C 4 grasses to subambient CO 2 and low light are largely species specific and only refined by photosynthetic subtype. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 101:1170-1184. [PMID: 31651067 DOI: 10.1111/tpj.14583] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 09/23/2019] [Accepted: 10/03/2019] [Indexed: 06/10/2023]
Abstract
Three subtypes of C4 photosynthesis exist (NADP-ME, NAD-ME and PEPCK), each known to be beneficial under specific environmental conditions. However, the influence of photosynthetic subtype on transcriptomic plasticity, as well as the genes underpinning this variability, remain largely unknown. Here, we comprehensively investigate the responses of six C4 grass species, spanning all three C4 subtypes, to two controlled environmental stresses: low light (200 µmol m-2 sec-1 ) and glacial CO2 (subambient; 180 ppm). We identify a susceptibility within NADP-ME species to glacial CO2 . Notably, although glacial CO2 phenotypes could be tied to C4 subtype, biochemical and transcriptomic responses to glacial CO2 were largely species specific. Nevertheless, we were able to identify subtype specific subsets of significantly differentially expressed transcripts which link resource acquisition and allocation to NADP-ME species susceptibility to glacial CO2 . Here, low light phenotypes were comparable across species with no clear subtype response, while again, transcriptomic responses to low light were largely species specific. However, numerous functional similarities were noted within the transcriptomic responses to low light, suggesting these responses are functionally relatively conserved. Additionally, PEPCK species exhibited heightened regulation of transcripts related to metabolism in response to both stresses, likely tied to their C4 metabolic pathway. These results highlight the influence that both species and subtype can have on plant responses to abiotic stress, building on our mechanistic understanding of acclimation within C4 grasses and highlighting avenues for future crop improvements.
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Affiliation(s)
- Alexander Watson-Lazowski
- Hawkesbury Institute for the Environment, University of Western Sydney, Locked Bag 1797, Penrith, NSW, 2751, Australia
- ARC Centre of Excellence for Translational Photosynthesis, Canberra, Australia
| | - Alexie Papanicolaou
- Hawkesbury Institute for the Environment, University of Western Sydney, Locked Bag 1797, Penrith, NSW, 2751, Australia
- ARC Centre of Excellence for Translational Photosynthesis, Canberra, Australia
| | - Fiona Koller
- Hawkesbury Institute for the Environment, University of Western Sydney, Locked Bag 1797, Penrith, NSW, 2751, Australia
- ARC Centre of Excellence for Translational Photosynthesis, Canberra, Australia
| | - Oula Ghannoum
- Hawkesbury Institute for the Environment, University of Western Sydney, Locked Bag 1797, Penrith, NSW, 2751, Australia
- ARC Centre of Excellence for Translational Photosynthesis, Canberra, Australia
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Post-Silking Shading Stress Affects Leaf Nitrogen Metabolism of Spring Maize in Southern China. PLANTS 2020; 9:plants9020210. [PMID: 32041314 PMCID: PMC7076639 DOI: 10.3390/plants9020210] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 01/21/2020] [Accepted: 02/04/2020] [Indexed: 11/17/2022]
Abstract
Lower sunlight caused by overcast skies from June to July in Southern China is one of the main environmental stresses that frequently occur and affect the post-silking growth and grain development of spring maize. In this study, a field trial involving four maize hybrids as materials was conducted to investigate the effects of post-silking shading stress (30% and 50% light deprivation) on leaf nitrogen metabolism and biomass accumulation during maize growing seasons in 2016 and 2017. Results indicated that 30% and 50% shading stress caused the grain yield to decrease by 47.3% and 69.6%, respectively. Plant post-silking biomass accumulation was decreased by shading, whereas the translocation from pre-silking assimilates in the vegetative organs was increased by shading. This change was sharply observed when the plants were deprived of more sunlight intensity. The leaf relative chlorophyll (soil and plant analyzer development (SPAD) value) and soluble protein contents were considerably decreased by shading under 50% light deprivation condition. The activities of nitrate reductase, glutamine synthetase and glutamate synthase that are involved in nitrogen metabolism were downregulated by shading stresses. In conclusion, nitrogen metabolism was disturbed by shading, which induced the decrease in post-silking dry matter accumulation, ultimately resulting in grain yield loss.
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Gao J, Liu Z, Zhao B, Liu P, Zhang JW. Physiological and comparative proteomic analysis provides new insights into the effects of shade stress in maize (Zea mays L.). BMC PLANT BIOLOGY 2020; 20:60. [PMID: 32024458 PMCID: PMC7003340 DOI: 10.1186/s12870-020-2264-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 01/23/2020] [Indexed: 05/08/2023]
Abstract
BACKGROUND Shade stress, a universal abiotic stress, suppresses plant growth and production seriously. However, little is known regarding the protein regulatory networks under shade stress. To better characterize the proteomic changes of maize leaves under shade stress, 60% shade (S) and supplementary lighting (L) on cloudy daylight from tasseling stage to physiological maturity stage were designed, the ambient sunlight treatment was used as control (CK). Isobaric tag for relative and absolute quantification (iTRAQ) technology was used to determine the proteome profiles in leaves. RESULTS Shading significantly decreased the SPAD value, net photosynthetic rate, and grain yield. During two experimental years, grain yields of S were reduced by 48 and 47%, and L increased by 6 and 11%, compared to CK. In total, 3958 proteins were identified by iTRAQ, and 2745 proteins were quantified including 349 proteins showed at least 1.2-fold changes in expression levels between treatments and CK. The differentially expressed proteins were classified into photosynthesis, stress defense, energy production, signal transduction, and protein and amino acid metabolism using the Web Gene Ontology Annotation Plot online tool. In addition, these proteins showed significant enrichment of the chloroplasts (58%) and cytosol (21%) for subcellular localization. CONCLUSIONS 60% shade induced the expression of proteins involved in photosynthetic electron transport chain (especially light-harvesting complex) and stress/defense/detoxification. However, the proteins related to calvin cycle, starch and sucrose metabolisms, glycolysis, TCA cycle, and ribosome and protein synthesis were dramatically depressed. Together, our results might help to provide a valuable resource for protein function analysis and also clarify the proteomic and physiological mechanism of maize underlying shade stress.
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Affiliation(s)
- Jia Gao
- State Key Laboratory of Crop Biology and College of Agronomy, Shandong Agricultural University, Taian, Shandong 271018 People’s Republic of China
| | - Zheng Liu
- State Key Laboratory of Crop Biology and College of Agronomy, Shandong Agricultural University, Taian, Shandong 271018 People’s Republic of China
| | - Bin Zhao
- State Key Laboratory of Crop Biology and College of Agronomy, Shandong Agricultural University, Taian, Shandong 271018 People’s Republic of China
| | - Peng Liu
- State Key Laboratory of Crop Biology and College of Agronomy, Shandong Agricultural University, Taian, Shandong 271018 People’s Republic of China
| | - Ji-Wang Zhang
- State Key Laboratory of Crop Biology and College of Agronomy, Shandong Agricultural University, Taian, Shandong 271018 People’s Republic of China
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Collison RF, Raven EC, Pignon CP, Long SP. Light, Not Age, Underlies the Maladaptation of Maize and Miscanthus Photosynthesis to Self-Shading. FRONTIERS IN PLANT SCIENCE 2020; 11:783. [PMID: 32733493 PMCID: PMC7358635 DOI: 10.3389/fpls.2020.00783] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 05/18/2020] [Indexed: 05/12/2023]
Abstract
Zea mays and Miscanthus × giganteus use NADP-ME subtype C4 photosynthesis and are important food and biomass crops, respectively. Both crops are grown in dense stands where shaded leaves can contribute a significant proportion of overall canopy productivity. This is because shaded leaves, despite intercepting little light, typically process light energy very efficiently for photosynthesis, when compared to light-saturated leaves at the top of the canopy. However, an apparently maladaptive loss in photosynthetic light-use efficiency as leaves become shaded has been shown to reduce productivity in these two species. It is unclear whether this is due to leaf aging or progressive shading from leaves forming above. This was resolved here by analysing photosynthesis in leaves of the same chronological age in the centre and exposed southern edge of field plots of these crops. Photosynthetic light-response curves were used to assess maximum quantum yield of photosynthesis; the key measure of photosynthetic capacity of a leaf in shade. Compared to the upper canopy, maximum quantum yield of photosynthesis of lower canopy leaves was significantly reduced in the plot centre; but increased slightly at the plot edge. This indicates loss of efficiency of shaded leaves is due not to aging, but to the altered light environment of the lower canopy, i.e., reduced light intensity and/or altered spectral composition. This work expands knowledge of the cause of this maladaptive shade response, which limits productivity of some of the world's most important crops.
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Affiliation(s)
- Robert F. Collison
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| | - Emma C. Raven
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| | - Charles P. Pignon
- Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, IL, United States
- Department of Crop Sciences, University of Illinois, Urbana, IL, United States
- Department of Plant Biology, University of Illinois, Urbana, IL, United States
| | - Stephen P. Long
- Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, IL, United States
- Department of Crop Sciences, University of Illinois, Urbana, IL, United States
- Department of Plant Biology, University of Illinois, Urbana, IL, United States
- Lancaster Environment Centre, Lancaster University, Lancaster, United Kingdom
- *Correspondence: Stephen P. Long,
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Wang Y, Zhang Z, Liang Y, Han Y, Han Y, Tan J. High Potassium Application Rate Increased Grain Yield of Shading-Stressed Winter Wheat by Improving Photosynthesis and Photosynthate Translocation. FRONTIERS IN PLANT SCIENCE 2020; 11:134. [PMID: 32184793 PMCID: PMC7058633 DOI: 10.3389/fpls.2020.00134] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 01/29/2020] [Indexed: 05/03/2023]
Abstract
Wheat (Triticum aestivum L) production on the Huang-Huai Plain of China has substantially affected in the past 50 years as a result of the decreasing total solar radiation and sunshine hours. Potassium has a significant effect on improving leaf photosynthesis ability under stress conditions. Five potassium application rates (K), 0 (K0), 50 (K50), 100 (K100), 150 (K150), and 250 (K250) mg K2O kg-1 soil, combined with two shading levels, no shading (NS) and shading at early filling stage for 10 days (SE), were used to investigate the effects of K application on winter wheat growth under SE condition. Under NS condition, the parameters related to chlorophyll fluorescence characteristics, dry matter productivity and grain yields reached the maximum values at a middle K application rate (100 mg K2O kg-1 soil). Shading stress significantly reduced leaf SPAD value, showed negative effects on chlorophyll fluorescence characteristics and reduced grain yield of winter wheat. However, as the result of the interaction of K×S, compared to NS condition, higher K application rate (150 mg and 250 K2O kg-1 soil) was beneficial in terms of achieving a higher grain yield of winter wheat under SE by improving leaf SPAD value, alleviating the damage of SE on the winter wheat photosynthetic system, and increasing fructan content and dry matter translocation percentage.
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Affiliation(s)
- Yi Wang
- College of Resources and Environment, Henan Agricultural University, Zhengzhou, China
- State Key Laboratory of Wheat and Maize Crop Science, Henan Agricultural University, Zhengzhou, China
- Collaborative Innovation Center of Henan Grain Crops, Henan Agricultural University, Zhengzhou, China
| | - Zhongkui Zhang
- College of Resources and Environment, Henan Agricultural University, Zhengzhou, China
| | - Yuanyuan Liang
- College of Resources and Environment, Henan Agricultural University, Zhengzhou, China
| | - Yulong Han
- College of Resources and Environment, Henan Agricultural University, Zhengzhou, China
| | - Yanlai Han
- College of Resources and Environment, Henan Agricultural University, Zhengzhou, China
- State Key Laboratory of Wheat and Maize Crop Science, Henan Agricultural University, Zhengzhou, China
- Collaborative Innovation Center of Henan Grain Crops, Henan Agricultural University, Zhengzhou, China
- *Correspondence: Yanlai Han, ; Jinfang Tan,
| | - Jinfang Tan
- College of Resources and Environment, Henan Agricultural University, Zhengzhou, China
- State Key Laboratory of Wheat and Maize Crop Science, Henan Agricultural University, Zhengzhou, China
- Collaborative Innovation Center of Henan Grain Crops, Henan Agricultural University, Zhengzhou, China
- *Correspondence: Yanlai Han, ; Jinfang Tan,
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Stavridou E, Webster RJ, Robson PRH. Novel Miscanthus genotypes selected for different drought tolerance phenotypes show enhanced tolerance across combinations of salinity and drought treatments. ANNALS OF BOTANY 2019; 124:653-674. [PMID: 31665760 PMCID: PMC6821188 DOI: 10.1093/aob/mcz009] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 01/11/2019] [Indexed: 05/05/2023]
Abstract
BACKGROUND AND AIMS Water deficit and salinity stresses are often experienced by plants concurrently; however, knowledge is limited about the effects of combined salinity and water deficit stress in plants, and especially in C4 bioenergy crops. Here we aim to understand how diverse drought tolerance traits may deliver tolerance to combinations of drought and salinity in C4 crops, and identify key traits that influence the productivity and biomass composition of novel Miscanthus genotypes under such conditions. METHODS Novel genotypes used included M. sinensis and M. floridulus species, pre-screened for different drought responses, plus the commercial accession Miscanthus × giganteus (M×g.). Plants were grown under control treatments, single stress or combinations of water deficit and moderate salinity stress. Morphophysiological responses, including growth, yield, gas exchange and leaf water relations and contents of proline, soluble sugars, ash and lignin were tested for significant genotypic and treatment effects. KEY RESULTS The results indicated that plants subjected to combined stresses showed more severe responses compared with single stresses. All novel drought-tolerant genotypes and M×g. were tolerant to moderate salinity stress. Biomass production in M. sinensis genotypes was more resilient to co-occurring stresses than that in M×g. and M. floridulus, which, despite the yield penalty produced more biomass overall. A stay-green M. sinensis genotype adopted a conservative growth strategy with few significant treatment effects. Proline biosynthesis was species-specific and was triggered by salinity and co-occurring stress treatments, mainly in M. floridulus. The ash content was compartmentalized differently in leaves and stems in the novel genotypes, indicating different mechanisms of ion accumulation. CONCLUSIONS This study highlights the potential to select novel drought-tolerant Miscanthus genotypes that are resilient to combinations of stress and is expected to contribute to a deeper fundamental knowledge of different mechanistic responses identified for further exploitation in developing resilient Miscanthus crops.
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Affiliation(s)
- Evangelia Stavridou
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, UK
- Institute of Applied Biosciences, Centre for Research and Technology Hellas, Thessaloniki, Greece
| | - Richard J Webster
- School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool, UK
| | - Paul R H Robson
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, UK
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Yabiku T, Ueno O. Structural and photosynthetic re-acclimation to low light in C4 maize leaves that developed under high light. ANNALS OF BOTANY 2019; 124:437-445. [PMID: 31127287 PMCID: PMC6798838 DOI: 10.1093/aob/mcz092] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 05/23/2019] [Indexed: 05/26/2023]
Abstract
BACKGROUND AND AIMS C4 plants have higher photosynthetic capacity than C3 plants, but this advantage comes at an energetic cost that is problematic under low light. In the crop canopy, lower leaves first develop under high light but later experience low light because of mutual shading. To explore the re-acclimation of C4 leaves to low light, we investigated the structural and physiological changes of the leaves of maize plants grown in shaded pots. METHODS Plants were first grown under high light, and then some of them were shaded (20 % of sunlight) for 3 weeks. Four types of leaves were examined: new leaves that developed under low light during shading (L), new leaves that developed under high light (H), mature leaves that developed under high light before shading and were then subjected to low light (H-L) and mature leaves that always experienced high light (H-H). KEY RESULTS The leaf mass per area, nitrogen and chlorophyll contents per unit leaf area, chlorophyll a/b ratio and activities of C3 and C4 photosynthetic enzymes were lower in H-L than in H-H leaves and in L than in H leaves. Unlike L leaves, H-L leaves maintained the thickness and framework of the Kranz anatomy of H leaves, but chloroplast contents in H-L leaves were reduced. This reduction of chloroplast contents was achieved mainly by reducing the size of chloroplasts. Although grana of mesophyll chloroplasts were more developed in L leaves than in H leaves, there were no differences between H-L and H-H leaves. The light curves of photosynthesis in H-L and L leaves were very similar and showed traits of shade leaves. CONCLUSIONS Mature maize leaves that developed under high light re-acclimate to low-light environments by adjusting their biochemical traits and chloroplast contents to resemble shade leaves but maintain the anatomical framework of sun leaves.
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Affiliation(s)
- Takayuki Yabiku
- Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Nishi-ku, Fukuoka, Japan
- NARO Tohoku Agricultural Research Center, Shimokuriyagawa, Morioka, Iwate, Japan
| | - Osamu Ueno
- Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Nishi-ku, Fukuoka, Japan
- Faculty of Agriculture, Kyushu University, Nishi-ku, Fukuoka, Japan
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21
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Bellasio C, Farquhar GD. A leaf-level biochemical model simulating the introduction of C 2 and C 4 photosynthesis in C 3 rice: gains, losses and metabolite fluxes. THE NEW PHYTOLOGIST 2019; 223:150-166. [PMID: 30859576 DOI: 10.1111/nph.15787] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 03/03/2019] [Indexed: 05/21/2023]
Abstract
This work aims at developing an adequate theoretical basis for comparing assimilation of the ancestral C3 pathway with CO2 concentrating mechanisms (CCM) that have evolved to reduce photorespiratory yield losses. We present a novel model for C3 , C2 , C2 + C4 and C4 photosynthesis simulating assimilatory metabolism, energetics and metabolite traffic at the leaf level. It integrates a mechanistic description of light reactions to simulate ATP and NADPH production, and a variable engagement of cyclic electron flow. The analytical solutions are compact and thus suitable for larger scale simulations. Inputs were derived with a comprehensive gas-exchange experiment. We show trade-offs in the operation of C4 that are in line with ecophysiological data. C4 has the potential to increase assimilation over C3 at high temperatures and light intensities, but this benefit is reversed under low temperatures and light. We apply the model to simulate the introduction of progressively complex levels of CCM into C3 rice, which feeds > 3.5 billion people. Increasing assimilation will require considerable modifications such as expressing the NAD(P)H Dehydrogenase-like complex and upregulating cyclic electron flow, enlarging the bundle sheath, and expressing suitable transporters to allow adequate metabolite traffic. The simpler C2 rice may be a desirable alternative.
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Affiliation(s)
- Chandra Bellasio
- Research School of Biology, Australian National University, Acton, ACT, 2601, Australia
- University of the Balearic Islands, Palma, Illes Balears, 07122, Spain
- Trees and Timber Institute, National Research Council of Italy, Sesto Fiorentino, Florence, 50019, Italy
| | - Graham D Farquhar
- Research School of Biology, Australian National University, Acton, ACT, 2601, Australia
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22
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Wen Z, Shi K, Lu W, Lu D. Effects of postsilking weak‐light stress on the flour quality of spring maize. Cereal Chem 2019. [DOI: 10.1002/cche.10170] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Zhangrong Wen
- Jiangsu Key Laboratory of Crop Genetics and Physiology/Jiangsu Key Laboratory of Crop Cultivation and Physiology Agricultural College of Yangzhou University Yangzhou China
| | - Kai Shi
- Jiangsu Key Laboratory of Crop Genetics and Physiology/Jiangsu Key Laboratory of Crop Cultivation and Physiology Agricultural College of Yangzhou University Yangzhou China
| | - Weiping Lu
- Jiangsu Key Laboratory of Crop Genetics and Physiology/Jiangsu Key Laboratory of Crop Cultivation and Physiology Agricultural College of Yangzhou University Yangzhou China
- Jiangsu Co‐Innovation Center for Modern Production Technology of Grain Crops/Joint International Research Laboratory of Agriculture and Agri‐Product Safety of the Ministry of Education of China Yangzhou University Yangzhou China
| | - Dalei Lu
- Jiangsu Key Laboratory of Crop Genetics and Physiology/Jiangsu Key Laboratory of Crop Cultivation and Physiology Agricultural College of Yangzhou University Yangzhou China
- Jiangsu Co‐Innovation Center for Modern Production Technology of Grain Crops/Joint International Research Laboratory of Agriculture and Agri‐Product Safety of the Ministry of Education of China Yangzhou University Yangzhou China
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23
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Pignon CP, Lundgren MR, Osborne CP, Long SP. Bundle sheath chloroplast volume can house sufficient Rubisco to avoid limiting C4 photosynthesis during chilling. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:357-365. [PMID: 30407578 PMCID: PMC6305190 DOI: 10.1093/jxb/ery345] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 09/13/2018] [Indexed: 05/15/2023]
Abstract
C4 leaves confine Rubisco to bundle sheath cells. Thus, the size of bundle sheath compartments and the total volume of chloroplasts within them limit the space available for Rubisco. Rubisco activity limits photosynthesis at low temperatures. C3 plants counter this limitation by increasing leaf Rubisco content, yet few C4 species do the same. Because C3 plants usually outperform C4 plants in chilling environments, it has been suggested that there is insufficient chloroplast volume available in the bundle sheath of C4 leaves to allow such an increase in Rubisco at low temperatures. We investigated this potential limitation by measuring bundle sheath and mesophyll compartment volumes and chloroplast contents, as well as leaf thickness and inter-veinal distance, in three C4 Andropogoneae grasses: two crops (Zea mays and Saccharum officinarum) and a wild, chilling-tolerant grass (Miscanthus × giganteus). A wild C4 Paniceae grass (Alloteropsis semialata) was also included. Despite significant structural differences between species, there was no evidence of increased bundle sheath chloroplast volume per leaf area available to the chilling-tolerant species, relative to the chilling-sensitive ones. Maximal theoretical photosynthetic capacity of the leaf far exceeded the photosynthetic rates achieved even at low temperatures. C4 bundle sheath cells therefore have the chloroplast volume to house sufficient Rubisco to avoid limiting C4 photosynthesis during chilling.
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Affiliation(s)
- Charles P Pignon
- University of Illinois, Carl R. Woese Institute for Genomic Biology and Departments of Crop Sciences and of Plant Biology, Urbana, IL, USA
| | - Marjorie R Lundgren
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, USA
- Arnold Arboretum, Harvard University, Boston, USA
- Lancaster Environment Centre, Lancaster University, Lancaster, UK
| | - Colin P Osborne
- Department of Animal and Plant Sciences, Alfred Denny Building, University of Sheffield, Sheffield, UK
| | - Stephen P Long
- University of Illinois, Carl R. Woese Institute for Genomic Biology and Departments of Crop Sciences and of Plant Biology, Urbana, IL, USA
- Lancaster Environment Centre, Lancaster University, Lancaster, UK
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Gao J, Shi J, Dong S, Liu P, Zhao B, Zhang J. Grain development and endogenous hormones in summer maize (Zea mays L.) submitted to different light conditions. INTERNATIONAL JOURNAL OF BIOMETEOROLOGY 2018; 62:2131-2138. [PMID: 30244320 DOI: 10.1007/s00484-018-1613-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 08/17/2018] [Accepted: 09/09/2018] [Indexed: 05/27/2023]
Abstract
Low light is a type of abiotic stress that seriously affects plant growth and production efficiency. We investigated the response mechanisms of summer maize to low light by measuring the changes in endogenous hormones in the grains and during grain filling in summer maize at different light intensities to provide a theoretical basis for the production and management of summer maize under light stress. We applied different light treatments in a field experiment as follows: S, shading from tassel stage (VT) to maturity stage (R6); CK, natural lighting in the field; and L, increasing light from VT to R6. The shading level was 60%, and the maximum illumination intensity of the increasing light treatment on cloudy days was 1600-1800 μmol m-2 s-1. Compared with the control, shading significantly increased the grain abscisic acid (ABA) content at 5-20 days after pollination and decreased the indole acetic acid (IAA), zeatin riboside (ZR), and gibberellin (GA) contents (P < 0.05). The grain-filling rate decreased under shading conditions. Meanwhile, the grain volume, grain weight, and yield all decreased; the yields in 2013 and 2014 decreased by 61 and 60%, respectively. The grain IAA, ZR, and GA contents were increased by increasing light. The grain ABA content at 5-20 days after pollination did not significantly differ from that of CK (P < 0.05). After 20 days after pollination, the ABA content decreased, the grain-filling rate and the filling duration increased, and the yield increased. However, shading after anthesis increased the grain ABA content and reduced the IAA, ZR, and GA contents. Grain growth and development were inhibited, and the yield decreased. The grain ABA content decreased; the IAA, ZR, and GA contents increased; and the yield increased after increasing light. The results indicate that different light intensities regulated the levels of grains endogenous hormones, which influenced the grain-filling rate and duration, and consequently, regulated grain weight and yield.
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Affiliation(s)
- Jia Gao
- State Key Laboratory of Crop Biology and College of Agronomy, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China
| | - Jianguo Shi
- State Key Laboratory of Crop Biology and College of Agronomy, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China
| | - Shuting Dong
- State Key Laboratory of Crop Biology and College of Agronomy, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China
| | - Peng Liu
- State Key Laboratory of Crop Biology and College of Agronomy, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China
| | - Bin Zhao
- State Key Laboratory of Crop Biology and College of Agronomy, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China
| | - Jiwang Zhang
- State Key Laboratory of Crop Biology and College of Agronomy, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China.
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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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Ubierna N, Holloway-Phillips MM, Farquhar GD. Using Stable Carbon Isotopes to Study C 3 and C 4 Photosynthesis: Models and Calculations. Methods Mol Biol 2018; 1770:155-196. [PMID: 29978402 DOI: 10.1007/978-1-4939-7786-4_10] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Stable carbon isotopes are a powerful tool to study photosynthesis. Initial applications consisted of determining isotope ratios of plant biomass using mass spectrometry. Subsequently, theoretical models relating C-isotope values to gas exchange characteristics were introduced and tested against instantaneous online measurements of 13C photosynthetic discrimination. Beginning in the twenty-first century, tunable diode laser spectroscopes with sufficient precision for determining isotope mixing ratios became commercially available. This has allowed collection of large data sets, at low cost and with unprecedented temporal resolution. With more data and accompanying knowledge, it has become apparent that there is a need for increased complexity in models and calculations. This chapter describes instantaneous online measurements of 13C photosynthetic discrimination, provides recommendations for experimental setup, and presents a thorough compilation of equations needed for different applications.
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Affiliation(s)
- Nerea Ubierna
- School of Biological Sciences, Molecular Plant Sciences, Washington State University, Pullman, WA, USA.
| | | | - Graham D Farquhar
- Research School of Biology, Australian National University, Canberra, ACT, Australia
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27
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Bellasio C, Quirk J, Buckley TN, Beerling DJ. A Dynamic Hydro-Mechanical and Biochemical Model of Stomatal Conductance for C 4 Photosynthesis. PLANT PHYSIOLOGY 2017; 175:104-119. [PMID: 28751312 PMCID: PMC5580762 DOI: 10.1104/pp.17.00666] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 07/24/2017] [Indexed: 05/10/2023]
Abstract
C4 plants are major grain (maize [Zea mays] and sorghum [Sorghum bicolor]), sugar (sugarcane [Saccharum officinarum]), and biofuel (Miscanthus spp.) producers and contribute ∼20% to global productivity. Plants lose water through stomatal pores in order to acquire CO2 (assimilation [A]) and control their carbon-for-water balance by regulating stomatal conductance (gS). The ability to mechanistically predict gS and A in response to atmospheric CO2, water availability, and time is critical for simulating stomatal control of plant-atmospheric carbon and water exchange under current, past, or future environmental conditions. Yet, dynamic mechanistic models for gS are lacking, especially for C4 photosynthesis. We developed and coupled a hydromechanical model of stomatal behavior with a biochemical model of C4 photosynthesis, calibrated using gas-exchange measurements in maize, and extended the coupled model with time-explicit functions to predict dynamic responses. We demonstrated the wider applicability of the model with three additional C4 grass species in which interspecific differences in stomatal behavior could be accounted for by fitting a single parameter. The model accurately predicted steady-state responses of gS to light, atmospheric CO2 and oxygen, soil drying, and evaporative demand as well as dynamic responses to light intensity. Further analyses suggest that the effect of variable leaf hydraulic conductance is negligible. Based on the model, we derived a set of equations suitable for incorporation in land surface models. Our model illuminates the processes underpinning stomatal control in C4 plants and suggests that the hydraulic benefits associated with fast stomatal responses of C4 grasses may have supported the evolution of C4 photosynthesis.
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Affiliation(s)
- Chandra Bellasio
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, United Kingdom
- Trees and Timber Institute, National Research Council of Italy, 50019 Florence, Italy
| | - Joe Quirk
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Thomas N Buckley
- Sydney Institute of Agriculture, University of Sydney, Narrabri, New South Wales 2390, Australia
| | - David J Beerling
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, United Kingdom
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28
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Gao J, Zhao B, Dong S, Liu P, Ren B, Zhang J. Response of Summer Maize Photosynthate Accumulation and Distribution to Shading Stress Assessed by Using 13CO 2 Stable Isotope Tracer in the Field. FRONTIERS IN PLANT SCIENCE 2017; 8:1821. [PMID: 29123536 PMCID: PMC5662628 DOI: 10.3389/fpls.2017.01821] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 10/06/2017] [Indexed: 05/11/2023]
Abstract
Maize is one of the most important crops globally that provides food, feed, and bioenergy. However, shading stress threatens maize production. In this study, we investigated the effects of shading on photosynthate accumulation and distribution of summer maize in the field. Zhengdan958 (ZD958) and Denghai 605 (DH605) were used as experimental materials in a field experiment running from 2013 to 2015. Shading treatments were applied over different growth stages: from the tassel stage (VT) to physiological maturity (R6) (S1), from the six-leaf stage (V6) to VT (S2), and from emergence stage (VE) to R6 (S3). The effects of shading on plant photosynthesis, photosynthate accumulation and distribution, and yield were evaluated in comparison to ambient sunlight. Shading significantly decreased the leaf area, SPAD value, net photosynthetic rate, dry matter accumulation, and grain yield. During the 3-year experimental period, grain yields of ZD958 and DH605 were reduced by 83.4%, 34.2%, 53.1% and 79.3%, 24.2%, 57.6% as compared to the CK by treatments S3, S2, and S1, respectively. 13CO2 stable isotope tracing revealed that shading differentially affected the photosynthate transfer rate in different stages; photosynthates were transferred from top to bottom plant parts, in the order control > S2 > S1 > S3. We conclude that shading clearly disrupted photosynthate metabolism, and reduced the photosynthate accumulation in the grain, resulting in a yield reduction.
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29
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Ma JY, Sun W, Koteyeva NK, Voznesenskaya E, Stutz SS, Gandin A, Smith-Moritz AM, Heazlewood JL, Cousins AB. Influence of light and nitrogen on the photosynthetic efficiency in the C 4 plant Miscanthus × giganteus. PHOTOSYNTHESIS RESEARCH 2017; 131:1-13. [PMID: 27531584 DOI: 10.1007/s11120-016-0281-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 05/26/2016] [Indexed: 06/06/2023]
Abstract
There are numerous studies describing how growth conditions influence the efficiency of C4 photosynthesis. However, it remains unclear how changes in the biochemical capacity versus leaf anatomy drives this acclimation. Therefore, the aim of this study was to determine how growth light and nitrogen availability influence leaf anatomy, biochemistry and the efficiency of the CO2 concentrating mechanism in Miscanthus × giganteus. There was an increase in the mesophyll cell wall surface area but not cell well thickness in the high-light (HL) compared to the low-light (LL) grown plants suggesting a higher mesophyll conductance in the HL plants, which also had greater photosynthetic capacity. Additionally, the HL plants had greater surface area and thickness of bundle-sheath cell walls compared to LL plants, suggesting limited differences in bundle-sheath CO2 conductance because the increased area was offset by thicker cell walls. The gas exchange estimates of phosphoenolpyruvate carboxylase (PEPc) activity were significantly less than the in vitro PEPc activity, suggesting limited substrate availability in the leaf due to low mesophyll CO2 conductance. Finally, leakiness was similar across all growth conditions and generally did not change under the different measurement light conditions. However, differences in the stable isotope composition of leaf material did not correlate with leakiness indicating that dry matter isotope measurements are not a good proxy for leakiness. Taken together, these data suggest that the CO2 concentrating mechanism in Miscanthus is robust under low-light and limited nitrogen growth conditions, and that the observed changes in leaf anatomy and biochemistry likely help to maintain this efficiency.
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Affiliation(s)
- Jian-Ying Ma
- Key Laboratory of Biogeography and Bioresource in Arid Land, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, 830011, China
- School of Biological Science, Washington State University, Pullman, WA, 99163, USA
| | - Wei Sun
- School of Biological Science, Washington State University, Pullman, WA, 99163, USA
- Institute of Grassland Science, Key Laboratory of Vegetation Ecology, Ministry of Education, Northeast Normal University, Changchun, 130024, China
| | - Nuria K Koteyeva
- Laboratory of Anatomy and Morphology, V.L. Komarov Botanical Institute of the Russian Academy of Sciences, St. Petersburg, Russia
| | - Elena Voznesenskaya
- Laboratory of Anatomy and Morphology, V.L. Komarov Botanical Institute of the Russian Academy of Sciences, St. Petersburg, Russia
| | - Samantha S Stutz
- School of Biological Science, Washington State University, Pullman, WA, 99163, USA
| | - Anthony Gandin
- School of Biological Science, Washington State University, Pullman, WA, 99163, USA
| | - Andreia M Smith-Moritz
- Joint BioEnergy Institute and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Joshua L Heazlewood
- Joint BioEnergy Institute and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- ARC Centre of Excellence in Plant Cell Walls, School of BioSciences, The University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Asaph B Cousins
- School of Biological Science, Washington State University, Pullman, WA, 99163, USA.
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30
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Bellasio C. A generalized stoichiometric model of C3, C2, C2+C4, and C4 photosynthetic metabolism. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:269-282. [PMID: 27535993 PMCID: PMC5853385 DOI: 10.1093/jxb/erw303] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 07/21/2016] [Indexed: 05/22/2023]
Abstract
The goal of suppressing photorespiration in crops to maximize assimilation and yield is stimulating considerable interest among researchers looking to bioengineer carbon-concentrating mechanisms into C3 plants. However, detailed quantification of the biochemical activities in the bundle sheath is lacking. This work presents a general stoichiometric model for C3, C2, C2+C4, and C4 assimilation (SMA) in which energetics, metabolite traffic, and the different decarboxylating enzymes (NAD-dependent malic enzyme, NADP-dependent malic enzyme, or phosphoenolpyruvate carboxykinase) are explicitly included. The SMA can be used to refine experimental data analysis or formulate hypothetical scenarios, and is coded in a freely available Microsoft Excel workbook. The theoretical underpinnings and general model behaviour are analysed with a range of simulations, including (i) an analysis of C3, C2, C2+C4, and C4 in operational conditions; (ii) manipulating photorespiration in a C3 plant; (iii) progressively upregulating a C2 shuttle in C3 photosynthesis; (iv) progressively upregulating a C4 cycle in C2 photosynthesis; and (v) manipulating processes that are hypothesized to respond to transient environmental inputs. Results quantify the functional trade-offs, such as the electron transport needed to meet ATP/NADPH demand, as well as metabolite traffic, inherent to different subtypes. The SMA refines our understanding of the stoichiometry of photosynthesis, which is of paramount importance for basic and applied research.
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Affiliation(s)
- Chandra Bellasio
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK
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31
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Bellasio C, Lundgren MR. Anatomical constraints to C4 evolution: light harvesting capacity in the bundle sheath. THE NEW PHYTOLOGIST 2016; 212:485-496. [PMID: 27375085 DOI: 10.1111/nph.14063] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 05/10/2016] [Indexed: 06/06/2023]
Abstract
In C4 photosynthesis CO2 assimilation and reduction are typically coordinated across mesophyll (M) and bundle sheath (BS) cells, respectively. This system consequently requires sufficient light to reach BS to generate enough ATP to allow ribulose-1,5-bisphosphate (RuBP) regeneration in BS. Leaf anatomy influences BS light penetration and therefore constrains C4 cycle functionality. Using an absorption scattering model (coded in Excel, and freely downloadable) we simulate light penetration profiles and rates of ATP production in BS across the C3 , C3 -C4 and C4 anatomical continua. We present a trade-off for light absorption between BS pigment concentration and space allocation. C3 BS anatomy limits light absorption and benefits little from high pigment concentrations. Unpigmented BS extensions increase BS light penetration. C4 and C3 -C4 anatomies have the potential to generate sufficient ATP in the BS, whereas typical C3 anatomy does not, except some C3 taxa closely related to C4 groups. Insufficient volume of BS, relative to M, will hamper a C4 cycle via insufficient BS light absorption. Thus, BS ATP production and RuBP regeneration, coupled with increased BS investments, allow greater operational plasticity. We propose that larger BS in C3 lineages may be co-opted for C3 -C4 and C4 biochemistry requirements.
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Affiliation(s)
- Chandra Bellasio
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK.
| | - Marjorie R Lundgren
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK
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32
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Effects of shading on the photosynthetic characteristics and mesophyll cell ultrastructure of summer maize. Naturwissenschaften 2016; 103:67. [PMID: 27437706 DOI: 10.1007/s00114-016-1392-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 06/28/2016] [Accepted: 07/01/2016] [Indexed: 10/21/2022]
Abstract
A field experiment was conducted to study the effects of shading on the photosynthetic characteristics and mesophyll cell ultrastructure of two summer maize hybrids Denghai605 (DH605) and Zhengdan958 (ZD958). The ambient sunlight treatment was used as control (CK) and shading treatments (40 % of ambient sunlight) were applied at different growth stages from silking (R1) to physiological maturity (R6) (S1), from the sixth leaf stage (V6) to R1 (S2), and from seeding to R6 (S3), respectively. The net photosynthetic rate (P n) was significantly decreased after shading. The greatest reduction of P n was found at S3 treatment, followed by S1 and S2 treatments. P n of S3 was decreased by 59 and 48 % for DH605, and 39 and 43 % for ZD958 at tasseling and milk-ripe stages, respectively, compared to that of CK. Additionally, leaf area index (LAI) and chlorophyll content decreased after shading. In terms of mesophyll cell ultrastructure, chloroplast configuration of mesophyll cells dispersed, and part of chloroplast swelled and became circular. Meanwhile, the major characteristics of chloroplasts showed poorly developed thylakoid structure at the early growth stage, blurry lamellar structure, loose grana, and a large gap between slices and warping granum. Then, plasmolysis occurred in mesophyll cells and the endomembrane system was destroyed, which resulted in the dissolution of cell membrane, karyotheca, mitochondria, and some membrane structures. The damaged mesophyll cell ultrastructure led to the decrease of photosynthetic capacity, and thus resulted in significant yield reduction by 45, 11, and 84 % in S1, S2, and S3 treatments, respectively, compared to that of CK.
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33
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Ellsworth PZ, Cousins AB. Carbon isotopes and water use efficiency in C4 plants. CURRENT OPINION IN PLANT BIOLOGY 2016; 31:155-61. [PMID: 27155062 DOI: 10.1016/j.pbi.2016.04.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 04/07/2016] [Accepted: 04/14/2016] [Indexed: 05/13/2023]
Abstract
Drought is a major agricultural problem worldwide. Therefore, selection for increased water use efficiency (WUE) in food and biofuel crop species will be an important trait in plant breeding programs. The leaf carbon isotopic composition (δ(13)Cleaf) has been suggested to serve as a rapid and effective high throughput phenotyping method for WUE in both C3 and C4 species. This is because WUE, leaf carbon discrimination (Δ(13)Cleaf), and δ(13)Cleaf are correlated through their relationships with intercellular to ambient CO2 partial pressures (Ci/Ca). However, in C4 plants, changing environmental conditions may influence photosynthetic efficiency (bundle-sheath leakiness) and post-photosynthetic fractionation that will potentially alter the relationship between δ(13)Cleaf and Ci/Ca. Here we discuss how these factors influence the relationship between δ(13)Cleaf and WUE, and the potential of using δ(13)Cleaf as a meaningful proxy for WUE.
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Affiliation(s)
| | - Asaph B Cousins
- Washington State University, Pullman, WA 99163, United States.
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34
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Bellasio C, Beerling DJ, Griffiths H. An Excel tool for deriving key photosynthetic parameters from combined gas exchange and chlorophyll fluorescence: theory and practice. PLANT, CELL & ENVIRONMENT 2016; 39:1180-97. [PMID: 25923517 DOI: 10.1111/pce.12560] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 02/10/2015] [Accepted: 02/25/2015] [Indexed: 05/23/2023]
Abstract
Combined photosynthetic gas exchange and modulated fluorometres are widely used to evaluate physiological characteristics associated with phenotypic and genotypic variation, whether in response to genetic manipulation or resource limitation in natural vegetation or crops. After describing relatively simple experimental procedures, we present the theoretical background to the derivation of photosynthetic parameters, and provide a freely available Excel-based fitting tool (EFT) that will be of use to specialists and non-specialists alike. We use data acquired in concurrent variable fluorescence-gas exchange experiments, where A/Ci and light-response curves have been measured under ambient and low oxygen. From these data, the EFT derives light respiration, initial PSII (photosystem II) photochemical yield, initial quantum yield for CO2 fixation, fraction of incident light harvested by PSII, initial quantum yield for electron transport, electron transport rate, rate of photorespiration, stomatal limitation, Rubisco (ribulose 1·5-bisphosphate carboxylase/oxygenase) rate of carboxylation and oxygenation, Rubisco specificity factor, mesophyll conductance to CO2 diffusion, light and CO2 compensation point, Rubisco apparent Michaelis-Menten constant, and Rubisco CO2 -saturated carboxylation rate. As an example, a complete analysis of gas exchange data on tobacco plants is provided. We also discuss potential measurement problems and pitfalls, and suggest how such empirical data could subsequently be used to parameterize predictive photosynthetic models.
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Affiliation(s)
- Chandra Bellasio
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK
| | - David J Beerling
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK
| | - Howard Griffiths
- Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK
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35
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Bellasio C, Beerling DJ, Griffiths H. Deriving C4 photosynthetic parameters from combined gas exchange and chlorophyll fluorescence using an Excel tool: theory and practice. PLANT, CELL & ENVIRONMENT 2016; 39:1164-79. [PMID: 26286697 DOI: 10.1111/pce.12626] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 08/06/2015] [Indexed: 05/27/2023]
Abstract
The higher photosynthetic potential of C4 plants has led to extensive research over the past 50 years, including C4 -dominated natural biomes, crops such as maize, or for evaluating the transfer of C4 traits into C3 lineages. Photosynthetic gas exchange can be measured in air or in a 2% Oxygen mixture using readily available commercial gas exchange and modulated PSII fluorescence systems. Interpretation of these data, however, requires an understanding (or the development) of various modelling approaches, which limit the use by non-specialists. In this paper we present an accessible summary of the theory behind the analysis and derivation of C4 photosynthetic parameters, and provide a freely available Excel Fitting Tool (EFT), making rigorous C4 data analysis accessible to a broader audience. Outputs include those defining C4 photochemical and biochemical efficiency, the rate of photorespiration, bundle sheath conductance to CO2 diffusion and the in vivo biochemical constants for PEP carboxylase. The EFT compares several methodological variants proposed by different investigators, allowing users to choose the level of complexity required to interpret data. We provide a complete analysis of gas exchange data on maize (as a model C4 organism and key global crop) to illustrate the approaches, their analysis and interpretation. © 2015 John Wiley & Sons Ltd.
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Affiliation(s)
- Chandra Bellasio
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK
| | - David J Beerling
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK
| | - Howard Griffiths
- Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK
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36
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Yin X, van der Putten PEL, Driever SM, Struik PC. Temperature response of bundle-sheath conductance in maize leaves. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:2699-714. [PMID: 26969744 PMCID: PMC4861018 DOI: 10.1093/jxb/erw104] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A small bundle-sheath conductance (g bs) is essential for the C4 CO2-concentrating mechanism to suppress photorespiration effectively. To predict the productivity of C4 crops accurately under global warming, it is necessary to examine whether and how g bs responds to temperature. We investigated the temperature response of g bs in maize by fitting a C4 photosynthesis model to combined gas exchange and chlorophyll fluorescence measurements of irradiance and CO2 response curves at 21% and 2% O2 within the range of 13.5-39 °C. The analysis was based on reported kinetic constants of C4 Rubisco and phosphoenolpyruvate carboxylase and temperature responses of C3 mesophyll conductance (g m). The estimates of g bs varied greatly with leaf temperature. The temperature response of g bs was well described by the peaked Arrhenius equation, with the optimum temperature being ~34 °C. The assumed temperature responses of g m had only a slight impact on the temperature response of g bs In contrast, using extreme values of some enzyme kinetic constants changed the shape of the response, from the peaked optimum response to the non-peaked Arrhenius pattern. Further studies are needed to confirm such an Arrhenius response pattern from independent measurement techniques and to assess whether it is common across C4 species.
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Affiliation(s)
- Xinyou Yin
- Centre for Crop Systems Analysis, Department of Plant Sciences, Wageningen University, PO Box 430, 6700 AK Wageningen, The Netherlands
| | - Peter E L van der Putten
- Centre for Crop Systems Analysis, Department of Plant Sciences, Wageningen University, PO Box 430, 6700 AK Wageningen, The Netherlands
| | - Steven M Driever
- Centre for Crop Systems Analysis, Department of Plant Sciences, Wageningen University, PO Box 430, 6700 AK Wageningen, The Netherlands
| | - Paul C Struik
- Centre for Crop Systems Analysis, Department of Plant Sciences, Wageningen University, PO Box 430, 6700 AK Wageningen, The Netherlands
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Yin X, Struik PC. Constraints to the potential efficiency of converting solar radiation into phytoenergy in annual crops: from leaf biochemistry to canopy physiology and crop ecology. JOURNAL OF EXPERIMENTAL BOTANY 2015. [PMID: 26224881 DOI: 10.1093/jxb/erv371] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
A new simple framework was proposed to quantify the efficiency of converting incoming solar radiation into phytoenergy in annual crops. It emphasizes the need to account for (i) efficiency gain when scaling up from the leaf level to the canopy level, and (ii) efficiency loss due to incomplete canopy closure during early and late phases of the crop cycle. Equations are given to estimate losses due to the constraints in various biochemical or physiological steps. For a given amount of daily radiation, a longer daytime was shown to increase energy use efficiency, because of the convex shape of the photosynthetic light response. Due to the higher cyclic electron transport, C4 leaves were found to have a lower energy loss via non-photochemical quenching, compared with C3 leaves. This contributes to the more linear light response in C4 than in C3 photosynthesis. Because of this difference in the curvature of the light response, canopy-to-leaf photosynthesis ratio, benefit from the optimum acclimation of the leaf nitrogen profile in the canopy, and productivity gain from future improvements in leaf photosynthetic parameters and canopy architecture were all shown to be higher in C3 than in C4 species. The indicative efficiency of converting incoming solar radiation into phytoenergy is ~2.2 and 3.0% in present C3 and C4 crops, respectively, when grown under well-managed conditions. An achievable efficiency via future genetic improvement was estimated to be as high as 3.6 and 4.1% for C3 and C4 crops, respectively.
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Affiliation(s)
- Xinyou Yin
- Centre for Crop Systems Analysis, Department of Plant Sciences, Wageningen University, PO Box 430, 6700 AK Wageningen, The Netherlands
| | - Paul C Struik
- Centre for Crop Systems Analysis, Department of Plant Sciences, Wageningen University, PO Box 430, 6700 AK Wageningen, The Netherlands
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Cui H, Camberato JJ, Jin L, Zhang J. Effects of shading on spike differentiation and grain yield formation of summer maize in the field. INTERNATIONAL JOURNAL OF BIOMETEOROLOGY 2015; 59:1189-200. [PMID: 25380975 DOI: 10.1007/s00484-014-0930-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2014] [Revised: 10/16/2014] [Accepted: 10/28/2014] [Indexed: 05/20/2023]
Abstract
A field experiment was conducted to study the effects of shading on tassel and ear development and yield formation of three summer maize hybrids Zhenjie 2 (ZJ2), Denghai 605 (DH605), and Zhengdan 958 (ZD958). The ambient sunlight treatment was used as control (CK) and shading treatments (40 % of ambient sunlight) were applied at different growth stages from silking stage (R1) to physiological maturity stage (R6) (treatment S1), from the sixth extended leaf stage (V6) to R1 (treatment S2) and from seeding to R6 (treatment S3). Shading had no significant effect on the time from seeding to shoot emergence (VE); however, subsequent growth and development were delayed with shading beyond this point. The differentiation time of both tassel and ear delayed, and female spike (tassel) floret differentiation, sexual organ formation time, and anthesis-silking interval (ASI) were lengthened. After shading, the total number of floret, silk, and fertilization floret reduced significantly; the number of abortive seeds increased, and the total setting percentage among different treatments showed that CK>S2>S1>S3; and the total setting percentages in S1, S2, and S3 of ZD958 were 44, 72, and 15 % respectively. The total floret number of tassel primordium differentiation, fertility rate, and seed setting rate of florets in S3 treatment was the minimum; kernels per ear decreased seriously and single ear setting percentage was only 16 %; although floret degeneration number of S2 during ear differentiation stages increased and floret fertility rate reduced than that of CK, fertilization flower seed production increased and abortive seed decreased after canceling shading. Aborted kernel of S1 increased and kernel dry weight reduced, resulting in a significant decrease of kernel number per ear and kernel weight, and the grain abortive rate of 40-62 %. In conclusion, shading changed the growth and development process and caused infertility of tassel and ear; tassel branches decreased, reducing pollen vitality and silks differentiation cut down; and grain dry matter accumulation and setting percentage decreased, causing yield reduction. Grain yield and biomass reduced 66, 36, and 93 % compared to the control by shading treatments of S1, S2, and S3, respectively.
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Affiliation(s)
- Haiyan Cui
- State Key Laboratory of Crop Biology, Agronomy College of Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China
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Burgess SJ, Hibberd JM. Insights into C4 metabolism from comparative deep sequencing. CURRENT OPINION IN PLANT BIOLOGY 2015; 25:138-144. [PMID: 26051034 DOI: 10.1016/j.pbi.2015.05.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 05/06/2015] [Accepted: 05/16/2015] [Indexed: 06/04/2023]
Abstract
C4 photosynthesis suppresses the oxygenation activity of Ribulose Bisphosphate Carboxylase Oxygenase and so limits photorespiration. Although highly complex, it is estimated to have evolved in 66 plant lineages, with the vast majority lacking sequenced genomes. Transcriptomics has recently initiated assessments of the degree to which transcript abundance differs between C3 and C4 leaves, identified novel components of C4 metabolism, and also led to mathematical models explaining the repeated evolution of this complex phenotype. Evidence is accumulating that this complex and convergent phenotype is partly underpinned by parallel evolution of structural genes, but also regulatory elements in both cis and trans. Furthermore, it appears that initial events associated with acquisition of C4 traits likely represent evolutionary exaptations related to non-photosynthetic processes.
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Affiliation(s)
- Steven J Burgess
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
| | - Julian M Hibberd
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK.
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Bellasio C, Burgess SJ, Griffiths H, Hibberd JM. A high throughput gas exchange screen for determining rates of photorespiration or regulation of C4 activity. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:3769-79. [PMID: 25006037 PMCID: PMC4085971 DOI: 10.1093/jxb/eru238] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Large-scale research programmes seeking to characterize the C4 pathway have a requirement for a simple, high throughput screen that quantifies photorespiratory activity in C3 and C4 model systems. At present, approaches rely on model-fitting to assimilatory responses (A/C i curves, PSII quantum yield) or real-time carbon isotope discrimination, which are complicated and time-consuming. Here we present a method, and the associated theory, to determine the effectiveness of the C4 carboxylation, carbon concentration mechanism (CCM) by assessing the responsiveness of V O/V C, the ratio of RuBisCO oxygenase to carboxylase activity, upon transfer to low O2. This determination compares concurrent gas exchange and pulse-modulated chlorophyll fluorescence under ambient and low O2, using widely available equipment. Run time for the procedure can take as little as 6 minutes if plants are pre-adapted. The responsiveness of V O/V C is derived for typical C3 (tobacco, rice, wheat) and C4 (maize, Miscanthus, cleome) plants, and compared with full C3 and C4 model systems. We also undertake sensitivity analyses to determine the impact of R LIGHT (respiration in the light) and the effectiveness of the light saturating pulse used by fluorescence systems. The results show that the method can readily resolve variations in photorespiratory activity between C3 and C4 plants and could be used to rapidly screen large numbers of mutants or transformants in high throughput studies.
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Affiliation(s)
- Chandra Bellasio
- Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
| | - Steven J Burgess
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
| | - Howard Griffiths
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
| | - Julian M Hibberd
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
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Kromdijk J, Ubierna N, Cousins AB, Griffiths H. Bundle-sheath leakiness in C4 photosynthesis: a careful balancing act between CO2 concentration and assimilation. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:3443-57. [PMID: 24755278 DOI: 10.1093/jxb/eru157] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Crop species with the C4 photosynthetic pathway are generally characterized by high productivity, especially in environmental conditions favouring photorespiration. In comparison with the ancestral C3 pathway, the biochemical and anatomical modifications of the C4 pathway allow spatial separation of primary carbon acquisition in mesophyll cells and subsequent assimilation in bundle-sheath cells. The CO2-concentrating C4 cycle has to operate in close coordination with CO2 reduction via the Calvin-Benson-Bassham (CBB) cycle in order to keep the C4 pathway energetically efficient. The gradient in CO2 concentration between bundle-sheath and mesophyll cells facilitates diffusive leakage of CO2. This rate of bundle-sheath CO2 leakage relative to the rate of phosphoenolpyruvate carboxylation (termed leakiness) has been used to probe the balance between C4 carbon acquisition and subsequent reduction as a result of environmental perturbations. When doing so, the correct choice of equations to derive leakiness from stable carbon isotope discrimination (Δ(13)C) during gas exchange is critical to avoid biased results. Leakiness responses to photon flux density, either short-term (during measurements) or long-term (during growth and development), can have important implications for C4 performance in understorey light conditions. However, recent reports show leakiness to be subject to considerable acclimation. Additionally, the recent discovery of two decarboxylating C4 cycles operating in parallel in Zea mays suggests that flexibility in the transported C4 acid and associated decarboxylase could also aid in maintaining C4/CBB balance in a changing environment. In this paper, we review improvements in methodology to estimate leakiness, synthesize reports on bundle-sheath leakiness, discuss different interpretations, and highlight areas where future research is necessary.
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Affiliation(s)
- Johannes Kromdijk
- Institute for Genomic Biology, University of Illinois, 1206W Gregory drive, Urbana, IL 61801, USA
| | - Nerea Ubierna
- Research School of Biology, The Australian National University, Canberra, ACT, Australia
| | - Asaph B Cousins
- School of Biological Sciences, Washington State University, Pullman, WA99164-4236, USA
| | - Howard Griffiths
- Physiological Ecology Group, Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB23EA, UK
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