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Kunz HH, Armbruster U, Mühlbauer S, de Vries J, Davis GA. Chloroplast ion homeostasis - what do we know and where should we go? THE NEW PHYTOLOGIST 2024; 243:543-559. [PMID: 38515227 DOI: 10.1111/nph.19661] [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: 07/01/2023] [Accepted: 02/01/2024] [Indexed: 03/23/2024]
Abstract
Plant yields heavily depend on proper macro- and micronutrient supply from the soil. In the leaf cells, nutrient ions fulfill specific roles in biochemical reactions, especially photosynthesis housed in the chloroplast. Here, a well-balanced ion homeostasis is maintained by a number of ion transport proteins embedded in the envelope and thylakoid membranes. Ten years ago, the first alkali metal transporters from the K+ EFFLUX ANTIPORTER family were discovered in the model plant Arabidopsis. Since then, our knowledge about the physiological importance of these carriers and their substrates has greatly expanded. New insights into the role of alkali ions in plastid gene expression and photoprotective mechanisms, both prerequisites for plant productivity in natural environments, were gained. The discovery of a Cl- channel in the thylakoid and several additional plastid alkali and alkali metal transport proteins have advanced the field further. Nevertheless, scientists still have long ways to go before a complete systemic understanding of the chloroplast's ion transportome will emerge. In this Tansley review, we highlight and discuss the achievements of the last decade. More importantly, we make recommendations on what areas to prioritize, so the field can reach the next milestones. One area, laid bare by our similarity-based comparisons among phototrophs is our lack of knowledge what ion transporters are used by cyanobacteria to buffer photosynthesis fluctuations.
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Affiliation(s)
- Hans-Henning Kunz
- Plant Biochemistry, Biology, LMU Munich, Großhadernerstr. 2-4, 82152, Planegg-Martinsried, Germany
| | - Ute Armbruster
- Institute of Molecular Photosynthesis, Heinrich Heine University Düsseldorf, 40225, Düsseldorf, Germany
- CEPLAS - Cluster of Excellence on Plant Sciences, Heinrich Heine University Düsseldorf, 40225, Düsseldorf, Germany
| | - Susanne Mühlbauer
- Plant Biochemistry, Biology, LMU Munich, Großhadernerstr. 2-4, 82152, Planegg-Martinsried, Germany
| | - Jan de Vries
- Department of Applied Bioinformatics, Institute for Microbiology and Genetics, Goettingen Center for Molecular Biosciences (GZMB), Campus Institute Data Science (CIDAS), University of Goettingen, Goldschmidtstr. 1, D-37077, Göttingen, Germany
| | - Geoffry A Davis
- Plant Biochemistry, Biology, LMU Munich, Großhadernerstr. 2-4, 82152, Planegg-Martinsried, Germany
- Department of Life Sciences, Imperial College London, London, SW7 2AZ, UK
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Lyu H, Zuo YS. Dynamic modulation of transthylakoid electric potential by chloroplast ATP synthases. Biochimie 2024; 221:27-37. [PMID: 38224902 DOI: 10.1016/j.biochi.2024.01.007] [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] [Received: 09/28/2023] [Revised: 12/07/2023] [Accepted: 01/12/2024] [Indexed: 01/17/2024]
Abstract
The light-induced transthylakoid membrane potential (ΔΨm) can function as a driving force to help catalyzing the formation of ATP molecules, proving a tight connection between ΔΨm and the ATP synthase. Naturally, a question can be raised on the effects of altered functioning of ATP synthases on regulating ΔΨm, which is attractive in the area of photosynthetic research. Lots of findings, when making efforts of solving this difficulty, can offer an in-depth understanding into the mechanism behind. However, the functional network on modulating ΔΨm is highly interdependent. It is difficult to comprehend the consequences of altered activity of ATP synthases on adjusting ΔΨm because parameters that have influences on ΔΨm would themselves be affected by ΔΨm. In this work, a computer model was applied to check the kinetic changes in polarization/depolarization across the thylakoid membrane (TM) regulated by the modified action of ATP synthases. The computing data revealed that under the extreme condition by numerically "switching off" the action of the ATP synthase, the complete inactivation of ATP synthase would markedly impede proton translocation at the cytb6f complex. Concurrently, the KEA3 (CLCe) porter, actively pumping protons into the stroma, further contributes to achieving a sustained low level of ΔΨm. Besides, the quantitative consequences on every particular component of ΔΨm adjusted by the modified functioning of ATP synthases were also explored. By employing the model, we bring evidence from the theoretical perspective that the ATP synthase is a key factor in forming a transmembrane proton loop thereby maintaining a propriate steady-state ΔΨm to meet variable environmental conditions.
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Affiliation(s)
- Hui Lyu
- School of Biological Science and Agriculture, Qiannan Normal University for Nationalities, Duyun, China.
| | - Yong-Song Zuo
- School of Biological Science and Agriculture, Qiannan Normal University for Nationalities, Duyun, China
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Shikanai T. Molecular Genetic Dissection of the Regulatory Network of Proton Motive Force in Chloroplasts. PLANT & CELL PHYSIOLOGY 2024; 65:537-550. [PMID: 38150384 DOI: 10.1093/pcp/pcad157] [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: 10/16/2023] [Revised: 11/27/2023] [Accepted: 12/08/2023] [Indexed: 12/29/2023]
Abstract
The proton motive force (pmf) generated across the thylakoid membrane rotates the Fo-ring of ATP synthase in chloroplasts. The pmf comprises two components: membrane potential (∆Ψ) and proton concentration gradient (∆pH). Acidification of the thylakoid lumen resulting from ∆pH downregulates electron transport in the cytochrome b6f complex. This process, known as photosynthetic control, is crucial for protecting photosystem I (PSI) from photodamage in response to fluctuating light. To optimize the balance between efficient photosynthesis and photoprotection, it is necessary to regulate pmf. Cyclic electron transport around PSI and pseudo-cyclic electron transport involving flavodiiron proteins contribute to the modulation of pmf magnitude. By manipulating the ratio between the two components of pmf, it is possible to modify the extent of photosynthetic control without affecting the pmf size. This adjustment can be achieved by regulating the movement of ions (such as K+ and Cl-) across the thylakoid membrane. Since ATP synthase is the primary consumer of pmf in chloroplasts, its activity must be precisely regulated to accommodate other mechanisms involved in pmf optimization. Although fragments of information about each regulatory process have been accumulated, a comprehensive understanding of their interactions is lacking. Here, I summarize current knowledge of the network for pmf regulation, mainly based on genetic studies.
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Affiliation(s)
- Toshiharu Shikanai
- Department of Botany, Graduate School of Science, Kyoto University, Kyoto, 606-8502 Japan
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Mattila H, Khorobrykh S, Tyystjärvi E. Both external and internal factors induce heterogeneity in senescing leaves of deciduous trees. FUNCTIONAL PLANT BIOLOGY : FPB 2024; 51:FP24012. [PMID: 38621018 DOI: 10.1071/fp24012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 03/23/2024] [Indexed: 04/17/2024]
Abstract
Autumn senescence is characterised by spatial and temporal heterogeneity. We show that senescing birch (Betula spp.) leaves had lower PSII activity (probed by the F V /F M chlorophyll a fluorescence parameter) in late autumn than in early autumn. We confirmed that PSII repair slows down with decreasing temperature, while rates of photodamage and recovery, measured under laboratory conditions at 20°C, were similar in these leaves. We propose that low temperatures during late autumn hinder repair and lead to accumulation of non-functional PSII units in senescing leaves. Fluorescence imaging of birch revealed that chlorophyll preferentially disappeared from inter-veinal leaf areas. These areas showed no recovery capacity and low non-photochemical quenching while green veinal areas of senescing leaves resembled green leaves. However, green and yellow leaf areas showed similar values of photochemical quenching. Analyses of thylakoids isolated from maple (Acer platanoides ) leaves showed that red, senescing leaves contained high amounts of carotenoids and α-tocopherol, and our calculations suggest that α-tocopherol was synthesised during autumn. Thylakoids isolated from red maple leaves produced little singlet oxygen, probably due to the high antioxidant content. However, the rate of PSII photodamage did not decrease. The data show that the heterogeneity of senescing leaves must be taken into account to fully understand autumn senescence.
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Affiliation(s)
- Heta Mattila
- Molecular Plant Biology, University of Turku, Turku, Finland; and Centre for Environmental and Marine Studies, University of Aveiro, Aveiro, Portugal
| | | | - Esa Tyystjärvi
- Molecular Plant Biology, University of Turku, Turku, Finland
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5
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Smith K, Strand DD, Kramer DM, Walker BJ. The role of photorespiration in preventing feedback regulation via ATP synthase in Nicotiana tabacum. PLANT, CELL & ENVIRONMENT 2024; 47:416-428. [PMID: 37937663 PMCID: PMC10842328 DOI: 10.1111/pce.14759] [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: 05/30/2023] [Revised: 10/17/2023] [Accepted: 10/23/2023] [Indexed: 11/09/2023]
Abstract
Photorespiration consumes substantial amounts of energy in the forms of adenosine triphosphate (ATP) and reductant making the pathway an important component in leaf energetics. Because of this high reductant demand, photorespiration is proposed to act as a photoprotective electron sink. However, photorespiration consumes more ATP relative to reductant than the C3 cycle meaning increased flux disproportionally increases ATP demand relative to reductant. Here we explore how energetic consumption from photorespiration impacts the flexibility of the light reactions in nicotiana tabacum. Specifically, we demonstrate that decreased photosynthetic efficiency (ϕII ) at low photorespiratory flux was related to feedback regulation at the chloroplast ATP synthase. Additionally, decreased ϕII at high photorespiratory flux resulted in the accumulation of photoinhibition at photosystem II centers. These results are contrary to the proposed role of photorespiration as a photoprotective electron sink. Instead, our results suggest a novel role of ATP consumption from photorespiration in maintaining ATP synthase activity, with implications for maintaining energy balance and preventing photodamage that will be critical for plant engineering strategies.
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Affiliation(s)
- Kaila Smith
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA
- Plant Biotechnology for Health and Sustainability Program, Michigan State University, East Lansing, MI 48824, USA
| | - Deserah D Strand
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA
| | - David M. Kramer
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Berkley J. Walker
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA
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Sugiura M, Kimura M, Shimamoto N, Takegawa Y, Nakamura M, Koyama K, Sellés J, Boussac A, Rutherford AW. Tuning of the Chl D1 and Chl D2 properties in photosystem II by site-directed mutagenesis of neighbouring amino acids. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2024; 1865:149013. [PMID: 37717932 DOI: 10.1016/j.bbabio.2023.149013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 09/01/2023] [Accepted: 09/11/2023] [Indexed: 09/19/2023]
Abstract
Photosystem II is the water/plastoquinone photo-oxidoreductase of photosynthesis. The photochemistry and catalysis occur in a quasi-symmetrical heterodimer, D1D2, that evolved from a homodimeric ancestor. Here, we studied site-directed mutants in PSII from the thermophilic cyanobacterium Thermosynechoccocus elongatus, focusing on the primary electron donor chlorophyll a in D1, ChlD1, and on its symmetrical counterpart in D2, ChlD2, which does not play a direct photochemical role. The main conserved amino acid specific to ChlD1 is D1/T179, which H-bonds the water ligand to its Mg2+, while its counterpart near ChlD2 is the non-H-bonding D2/I178. The symmetrical-swapped mutants, D1/T179I and D2/I178T, and a second ChlD2 mutant, D2/I178H, were studied. The D1 mutations affected the 686 nm absorption attributed to ChlD1, while the D2 mutations affected a 663 nm feature, tentatively attributed to ChlD2. The mutations had little effect on enzyme activity and forward electron transfer, reflecting the robustness of the overall enzyme function. In contrast, the mutations significantly affected photodamage and protective mechanisms, reflecting the importance of redox tuning in these processes. In D1/T179I, the radical pair recombination triplet on ChlD1 was shared onto a pheophytin, presumably PheD1 and the detection of 3PheD1 supports the proposed mechanism for the anomalously short lifetime of 3ChlD1; e.g. electron transfer quenching by QA- of 3PheD1 after triplet transfer from 3ChlD1. In D2/I178T, a charge separation could occur between ChlD2 and PheD2, a reaction that is thought to occur in ancestral precursors of PSII. These mutants help understand the evolution of asymmetry in PSII.
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Affiliation(s)
- Miwa Sugiura
- Proteo-Science Research Center, Department of Chemistry, Graduate School of Science and Technology, Ehime University, Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan.
| | - Masaya Kimura
- Proteo-Science Research Center, Department of Chemistry, Graduate School of Science and Technology, Ehime University, Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - Naohiro Shimamoto
- Proteo-Science Research Center, Department of Chemistry, Graduate School of Science and Technology, Ehime University, Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - Yuki Takegawa
- Proteo-Science Research Center, Department of Chemistry, Graduate School of Science and Technology, Ehime University, Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - Makoto Nakamura
- Proteo-Science Research Center, Department of Chemistry, Graduate School of Science and Technology, Ehime University, Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - Kazumi Koyama
- Proteo-Science Research Center, Department of Chemistry, Graduate School of Science and Technology, Ehime University, Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - Julien Sellés
- Institut de Biologie Physico-Chimique, UMR CNRS 7141 and Sorbonne Université, 13 rue Pierre et Marie Curie, 75005 Paris, France
| | - Alain Boussac
- Institut de Biologie Intégrative de la Cellule, UMR9198, CEA Saclay, 91191 Gif-Sur-Yvette, France.
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7
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Semenov AY, Tikhonov AN. Electrometric and Electron Paramagnetic Resonance Measurements of a Difference in the Transmembrane Electrochemical Potential: Photosynthetic Subcellular Structures and Isolated Pigment-Protein Complexes. MEMBRANES 2023; 13:866. [PMID: 37999352 PMCID: PMC10673362 DOI: 10.3390/membranes13110866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 10/23/2023] [Accepted: 10/26/2023] [Indexed: 11/25/2023]
Abstract
A transmembrane difference in the electrochemical potentials of protons (ΔμH+) serves as a free energy intermediate in energy-transducing organelles of the living cell. The contributions of two components of the ΔμH+ (electrical, Δψ, and concentrational, ΔpH) to the overall ΔμH+ value depend on the nature and lipid composition of the energy-coupling membrane. In this review, we briefly consider several of the most common instrumental (electrometric and EPR) methods for numerical estimations of Δψ and ΔpH. In particular, the kinetics of the flash-induced electrometrical measurements of Δψ in bacterial chromatophores, isolated bacterial reaction centers, and Photosystems I and II of the oxygenic photosynthesis, as well as the use of pH-sensitive molecular indicators and kinetic data regarding pH-dependent electron transport in chloroplasts, have been reviewed. Further perspectives on the application of these methods to solve some fundamental and practical problems of membrane bioenergetics are discussed.
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Affiliation(s)
- Alexey Yu. Semenov
- A.N. Belozersky Institute of Physical-Chemical Biology, M.V. Lomonosov Moscow State University, 119991 Moscow, Russia;
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8
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Zheng Q, Hu J, Tan Q, Hu H, Sun C, Lei K, Tian Z, Dai T. Improved chloroplast Pi allocation helps sustain electron transfer to enhance photosynthetic low-phosphorus tolerance of wheat. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2023; 201:107880. [PMID: 37437346 DOI: 10.1016/j.plaphy.2023.107880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 06/24/2023] [Accepted: 07/05/2023] [Indexed: 07/14/2023]
Abstract
Phosphorus (P) deficit limits high wheat (Triticum aestivum L.) yields. Breeding low-P-tolerant cultivars is vital for sustainable agriculture and food security, but the low-P adaptation mechanisms are largely not understood. Two wheat cultivars, ND2419 (low-P-tolerant) and ZM366 (low-P-sensitive) were used in this study. They were grown under hydroponic conditions with low-P (0.015 mM) or normal-P (1 mM). Low-P suppressed biomass accumulation and net photosynthetic rate (A) in both cultivars, whereas ND2419 was relatively less suppressed. Intercellular CO2 concentration did not decrease with the decline of stomatal conductance. Additionally, maximum electron transfer rate (Jmax) decreased sooner than maximum carboxylation rate (Vcmax). Results indicate that impeded electron transfer is directly responsible for decreased A. Under low-P, ND2419 exhibited greater PSII functionality (potential activity (Fv/Fo), maximum quantum efficiency (Fv/Fm), photochemical quenching (qL) and non-photochemical quenching (NPQ) required for electron transfer than ZM366, resulting more ATP for Rubisco activation. Furthermore, ND2419 maintained higher chloroplast Pi concentrations by enhancing chloroplast Pi allocation, compared with ZM366. Overall, the low-P-tolerant cultivar sustained electron transfer under low-P by enhancing chloroplast Pi allocation, allowing more ATP synthesis for Rubisco activation, ultimately presenting stronger photosynthesis capacities. The improved chloroplasts Pi allocation may provide new insights into improve low-P tolerance.
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Affiliation(s)
- Qiaomei Zheng
- Key Laboratory of Crop Physiology Ecology and Production Management of Ministry of Agriculture, Nanjing Agricultural University, Nanjing, Jiangsu Province, 210095, People's Republic of China.
| | - Jinling Hu
- Key Laboratory of Crop Physiology Ecology and Production Management of Ministry of Agriculture, Nanjing Agricultural University, Nanjing, Jiangsu Province, 210095, People's Republic of China.
| | - Qingwen Tan
- Key Laboratory of Crop Physiology Ecology and Production Management of Ministry of Agriculture, Nanjing Agricultural University, Nanjing, Jiangsu Province, 210095, People's Republic of China.
| | - Hang Hu
- Key Laboratory of Crop Physiology Ecology and Production Management of Ministry of Agriculture, Nanjing Agricultural University, Nanjing, Jiangsu Province, 210095, People's Republic of China.
| | - Chuanjiao Sun
- Key Laboratory of Crop Physiology Ecology and Production Management of Ministry of Agriculture, Nanjing Agricultural University, Nanjing, Jiangsu Province, 210095, People's Republic of China.
| | - Kangqi Lei
- Key Laboratory of Crop Physiology Ecology and Production Management of Ministry of Agriculture, Nanjing Agricultural University, Nanjing, Jiangsu Province, 210095, People's Republic of China.
| | - Zhongwei Tian
- Key Laboratory of Crop Physiology Ecology and Production Management of Ministry of Agriculture, Nanjing Agricultural University, Nanjing, Jiangsu Province, 210095, People's Republic of China.
| | - Tingbo Dai
- Key Laboratory of Crop Physiology Ecology and Production Management of Ministry of Agriculture, Nanjing Agricultural University, Nanjing, Jiangsu Province, 210095, People's Republic of China.
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9
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Shevela D, Kern JF, Govindjee G, Messinger J. Solar energy conversion by photosystem II: principles and structures. PHOTOSYNTHESIS RESEARCH 2023; 156:279-307. [PMID: 36826741 PMCID: PMC10203033 DOI: 10.1007/s11120-022-00991-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 12/01/2022] [Indexed: 05/23/2023]
Abstract
Photosynthetic water oxidation by Photosystem II (PSII) is a fascinating process because it sustains life on Earth and serves as a blue print for scalable synthetic catalysts required for renewable energy applications. The biophysical, computational, and structural description of this process, which started more than 50 years ago, has made tremendous progress over the past two decades, with its high-resolution crystal structures being available not only of the dark-stable state of PSII, but of all the semi-stable reaction intermediates and even some transient states. Here, we summarize the current knowledge on PSII with emphasis on the basic principles that govern the conversion of light energy to chemical energy in PSII, as well as on the illustration of the molecular structures that enable these reactions. The important remaining questions regarding the mechanism of biological water oxidation are highlighted, and one possible pathway for this fundamental reaction is described at a molecular level.
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Affiliation(s)
- Dmitry Shevela
- Department of Chemistry, Chemical Biological Centre, Umeå University, 90187, Umeå, Sweden.
| | - Jan F Kern
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Govindjee Govindjee
- Department of Plant Biology, Department of Biochemistry and Center of Biophysics & Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Johannes Messinger
- Department of Chemistry, Chemical Biological Centre, Umeå University, 90187, Umeå, Sweden.
- Molecular Biomimetics, Department of Chemistry - Ångström, Uppsala University, 75120, Uppsala, Sweden.
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Degen GE, Jackson PJ, Proctor MS, Zoulias N, Casson SA, Johnson MP. High cyclic electron transfer via the PGR5 pathway in the absence of photosynthetic control. PLANT PHYSIOLOGY 2023; 192:370-386. [PMID: 36774530 PMCID: PMC10152662 DOI: 10.1093/plphys/kiad084] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Accepted: 01/24/2023] [Indexed: 05/03/2023]
Abstract
The light reactions of photosynthesis couple electron and proton transfers across the thylakoid membrane, generating NADPH, and proton motive force (pmf) that powers the endergonic synthesis of ATP by ATP synthase. ATP and NADPH are required for CO2 fixation into carbohydrates by the Calvin-Benson-Bassham cycle. The dominant ΔpH component of the pmf also plays a photoprotective role in regulating photosystem II light harvesting efficiency through nonphotochemical quenching (NPQ) and photosynthetic control via electron transfer from cytochrome b6f (cytb6f) to photosystem I. ΔpH can be adjusted by increasing the proton influx into the thylakoid lumen via upregulation of cyclic electron transfer (CET) or decreasing proton efflux via downregulation of ATP synthase conductivity (gH+). The interplay and relative contributions of these two elements of ΔpH control to photoprotection are not well understood. Here, we showed that an Arabidopsis (Arabidopsis thaliana) ATP synthase mutant hunger for oxygen in photosynthetic transfer reaction 2 (hope2) with 40% higher proton efflux has supercharged CET. Double crosses of hope2 with the CET-deficient proton gradient regulation 5 and ndh-like photosynthetic complex I lines revealed that PROTON GRADIENT REGULATION 5 (PGR5)-dependent CET is the major pathway contributing to higher proton influx. PGR5-dependent CET allowed hope2 to maintain wild-type levels of ΔpH, CO2 fixation and NPQ, however photosynthetic control remained absent and PSI was prone to photoinhibition. Therefore, high CET in the absence of ATP synthase regulation is insufficient for PSI photoprotection.
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Affiliation(s)
- Gustaf E Degen
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Philip J Jackson
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield S1 4NL, UK
| | - Matthew S Proctor
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Nicholas Zoulias
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Stuart A Casson
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Matthew P Johnson
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
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11
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Strand DD, Karcher D, Ruf S, Schadach A, Schöttler MA, Sandoval-Ibañez O, Hall D, Kramer DM, Bock R. Characterization of mutants deficient in N-terminal phosphorylation of the chloroplast ATP synthase subunit β. PLANT PHYSIOLOGY 2023; 191:1818-1835. [PMID: 36635853 PMCID: PMC10022623 DOI: 10.1093/plphys/kiad013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 12/05/2022] [Indexed: 06/17/2023]
Abstract
Understanding the regulation of photosynthetic light harvesting and electron transfer is of great importance to efforts to improve the ability of the electron transport chain to supply downstream metabolism. A central regulator of the electron transport chain is ATP synthase, the molecular motor that harnesses the chemiosmotic potential generated from proton-coupled electron transport to synthesize ATP. ATP synthase is regulated both thermodynamically and post-translationally, with proposed phosphorylation sites on multiple subunits. In this study we focused on two N-terminal serines on the catalytic subunit β in tobacco (Nicotiana tabacum), previously proposed to be important for dark inactivation of the complex to avoid ATP hydrolysis at night. Here we show that there is no clear role for phosphorylation in the dark inactivation of ATP synthase. Instead, mutation of one of the two phosphorylated serine residues to aspartate to mimic constitutive phosphorylation strongly decreased ATP synthase abundance. We propose that the loss of N-terminal phosphorylation of ATPβ may be involved in proper ATP synthase accumulation during complex assembly.
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Affiliation(s)
| | - Daniel Karcher
- Max-Planck-Institut für Molecular Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Stephanie Ruf
- Max-Planck-Institut für Molecular Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Anne Schadach
- Max-Planck-Institut für Molecular Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Mark A Schöttler
- Max-Planck-Institut für Molecular Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Omar Sandoval-Ibañez
- Max-Planck-Institut für Molecular Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - David Hall
- DOE Plant Research Laboratory, Michigan State University, 612 Wilson Rd 106, East Lansing, Michigan, 48824, USA
| | - David M Kramer
- DOE Plant Research Laboratory, Michigan State University, 612 Wilson Rd 106, East Lansing, Michigan, 48824, USA
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12
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Lyu H, Lazár D. Effect of ion fluxes on regulating the light-induced transthylakoid electric potential difference. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2023; 194:60-69. [PMID: 36379178 DOI: 10.1016/j.plaphy.2022.10.028] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 10/11/2022] [Accepted: 10/29/2022] [Indexed: 06/16/2023]
Abstract
The light-induced transthylakoid membrane potential (ΔΨ) can not only drive the ATP synthesis through the ATP-synthase in chloroplasts but serve as an essential modifier in the acclimation of photosynthesis to fluctuating light conditions. It has been manifested that during photosynthesis, the light-induced ΔΨ is responsive to multiple factors among which the ion channels/transporters (e.g., V-K+, VCCN1, and KEA3) are key to adjust the ion distribution on the two sides of the thylakoid membrane and hence shape the kinetics of ΔΨ. However, an in-depth mechanistic understanding of ion fluxes on adjusting the transthylakoid electric potentials is still unclear. This lack of a mechanistic understanding is due to the experimental difficulty of closely observing ion fluxes in vivo and also hacking the evolution of parameters in a highly intertwined photosynthetic network. In this work, a computer model was applied to investigate the roles of ion fluxes on adjusting transthylakoid electric potentials upon a temporal cycle of a period of high illumination followed by a dark-adapted phase. The computing data revealed that, firstly, upon illumination, the dissipation of the steady-ΔΨ by ∼10 mV is contributed from the V-K+-driven K+ flux whilst ∼8 mV of the steady-ΔΨ is dissipated by the VCCN1-pumped Cl- flux, but there were no appreciable KEA3-evoked variations on ΔΨ; secondly, on transition from high light to darkness, V-K+ and KEA3 are serving as major contributors whereas VCCN1 taking a counterbalancing part in shaping a standard trace of ECS (electrochromic shift), which commonly shows a sharp fall to a minimum before returning to the baseline in darkness. Besides, the functional consequences on components of ΔΨ adjusted by every particular ion channel/transporter were also explored. By employing the model, we bring evidence that particular thylakoid-harbored proteins, namely V-K+, VCCN1, and KEA3, function by distinct mechanisms in the dynamic adjustment of electric potential, which might be mainly importnat under fluctuating light conditions.
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Affiliation(s)
- Hui Lyu
- School of Biological Science and Agriculture, Qiannan Normal University for Nationalities, Duyun, China.
| | - Dušan Lazár
- Department of Biophysics, Faculty of Science, Palacký University, Olomouc, Czech Republic.
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13
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Mattila H, Mishra S, Tyystjärvi T, Tyystjärvi E. Singlet oxygen production by photosystem II is caused by misses of the oxygen evolving complex. THE NEW PHYTOLOGIST 2023; 237:113-125. [PMID: 36161283 PMCID: PMC10092662 DOI: 10.1111/nph.18514] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 09/10/2022] [Indexed: 06/12/2023]
Abstract
Singlet oxygen (1 O2 ) is a harmful species that functions also as a signaling molecule. In chloroplasts, 1 O2 is produced via charge recombination reactions in photosystem II, but which recombination pathway(s) produce triplet Chl and 1 O2 remains open. Furthermore, the role of 1 O2 in photoinhibition is not clear. We compared temperature dependences of 1 O2 production, photoinhibition, and recombination pathways. 1 O2 production by pumpkin thylakoids increased from -2 to +35°C, ruling out recombination of the primary charge pair as a main contributor. S2 QA - or S2 QB - recombination pathways, in turn, had too steep temperature dependences. Instead, the temperature dependence of 1 O2 production matched that of misses (failures of the oxygen (O2 ) evolving complex to advance an S-state). Photoinhibition in vitro and in vivo (also in Synechocystis), and in the presence or absence of O2 , had the same temperature dependence, but ultraviolet (UV)-radiation-caused photoinhibition showed a weaker temperature response. We suggest that the miss-associated recombination of P680 + QA - is the main producer of 1 O2 . Our results indicate three parallel photoinhibition mechanisms. The manganese mechanism dominates in UV radiation but also functions in white light. Mechanisms that depend on light absorption by Chls, having 1 O2 or long-lived P680 + as damaging agents, dominate in red light.
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Affiliation(s)
- Heta Mattila
- Department of Life Technologies/Molecular Plant BiologyUniversity of TurkuFI‐20014TurkuFinland
| | - Sujata Mishra
- Department of Life Technologies/Molecular Plant BiologyUniversity of TurkuFI‐20014TurkuFinland
| | - Taina Tyystjärvi
- Department of Life Technologies/Molecular Plant BiologyUniversity of TurkuFI‐20014TurkuFinland
| | - Esa Tyystjärvi
- Department of Life Technologies/Molecular Plant BiologyUniversity of TurkuFI‐20014TurkuFinland
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14
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Alameldin HF, Montgomery BL. Plasticity of Arabidopsis rosette transcriptomes and photosynthetic responses in dynamic light conditions. PLANT DIRECT 2023; 7:e475. [PMID: 36628154 PMCID: PMC9822700 DOI: 10.1002/pld3.475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 12/03/2022] [Accepted: 12/06/2022] [Indexed: 06/17/2023]
Abstract
With the high variability of natural growth environments, plants exhibit flexibility and resilience in regard to the strategies they employ to maintain overall fitness, including maximizing light use for photosynthesis, while simultaneously limiting light-associated damage. We measured distinct parameters of photosynthetic performance of Arabidopsis thaliana plants under dynamic light regimes. Plants were grown to maturity then subjected to the following 5-day (16 h light, 8 h dark) regime: Day 1 at constant light (CL) intensity during light period, representative of a common lab growth condition; Day 2 under sinusoidal variation in light intensity (SL) during the light period that is representative of changes occurring during a clear sunny day; Day 3 under fluctuating light (FL) intensity during the light period that simulates sudden changes that might occur with the movements of clouds in and out of the view of the sun; Day 4, repeat of CL; and Day 5, repeat of FL. We also examined the global transcriptome profile in these growth conditions based on obtaining RNA-sequencing (RNA-seq) data for whole plant rosettes. Our transcriptomic analyses indicated downregulation of photosystem I (PSI) and II (PSII) associated genes, which were correlated with elevated levels of photoinhibition as indicated by measurements of nonphotochemical quenching (NPQ), energy-dependent quenching (qE), and inhibitory quenching (qI) under both SL and FL conditions. Furthermore, our transcriptomic results indicated downregulation of tetrapyrrole biosynthesis associated genes, coupled with reduced levels of chlorophyll under both SL and FL compared with CL, as well as downregulation of photorespiration-associated genes under SL. We also noticed an enrichment of the stress response gene ontology (GO) terms for genes differentially regulated under FL when compared with SL. Collectively, our phenotypic and transcriptome analyses serve as useful resources for probing the underlying molecular mechanisms associated with plant acclimation to rapid light intensity changes in the natural environment.
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Affiliation(s)
- Hussien F. Alameldin
- DOE‐Plant Research LaboratoryMichigan State UniversityEast LansingMichiganUSA
- Agricultural Genetic Engineering Research Institute (AGERI)Agriculture Research Center (ARC)GizaEgypt
| | - Beronda L. Montgomery
- DOE‐Plant Research LaboratoryMichigan State UniversityEast LansingMichiganUSA
- Department of Biochemistry and Molecular BiologyMichigan State UniversityEast LansingMichiganUSA
- Department of Microbiology and Molecular GeneticsMichigan State UniversityEast LansingMichiganUSA
- Department of BiologyGrinnell CollegeGrinnellIowaUSA
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15
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Mattila H, Tyystjärvi E. Light-induced damage to photosystem II at a very low temperature (195 K) depends on singlet oxygen. PHYSIOLOGIA PLANTARUM 2022; 174:e13824. [PMID: 36377045 PMCID: PMC10099935 DOI: 10.1111/ppl.13824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 10/26/2022] [Accepted: 11/07/2022] [Indexed: 06/16/2023]
Abstract
Photosynthetic organisms, like evergreen plants, may encounter strong light at low temperatures. Light, despite being the energy source of photosynthesis, irreversibly damages photosystem II (PSII). We illuminated plant thylakoid membranes and intact cyanobacterial cells at -78.5°C and assayed PSII activity with oxygen evolution or chlorophyll fluorescence, after thawing the sample. Both UV radiation and visible light damaged PSII of pumpkin (Cucurbita maxima) thylakoids at -78.5°C, but visible-light-induced photoinhibition at -78.5°C, unlike at +20°C, proceeded only in the presence of oxygen. A strong magnetic field that would decrease triplet chlorophyll formation by recombination of the primary radical pair slowed down photoinhibition at -78.5°C, suggesting that singlet oxygen produced via recombination of the primary pair is a major contributor to photoinhibition at -78.5°C. However, a magnetic field did not affect singlet oxygen production at +25°C. Thylakoids of winter leaves of an evergreen plant, Bergenia, were less susceptible to photoinhibition both at -78.5°C and +20°C, contained high amounts of carotenoids and produced little singlet oxygen (measured at +20°C), compared to thylakoids of summer leaves. In contrast, high carotenoid amount and low singlet oxygen yield did not protect a Synechocystis mutant from photoinhibition at -78.5°C. Thylakoids isolated from Arabidopsis thaliana grown under high light, which reduces PSII antenna size, were more resistant than control plants against photoinhibition at -78.5°C but not at +20°C, although carotenoid amounts were similar. The results indicate that visible-light-induced photoinhibition at -78.5°C depends on singlet oxygen, whereas photoinhibition at +20°C is largely independent of oxygen.
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Affiliation(s)
- Heta Mattila
- Department of Life Technologies/Molecular Plant BiologyUniversity of TurkuTurkuFinland
| | - Esa Tyystjärvi
- Department of Life Technologies/Molecular Plant BiologyUniversity of TurkuTurkuFinland
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16
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Lazár D, Niu Y, Nedbal L. Insights on the regulation of photosynthesis in pea leaves exposed to oscillating light. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:6380-6393. [PMID: 36036782 PMCID: PMC9578350 DOI: 10.1093/jxb/erac283] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 08/26/2022] [Indexed: 06/15/2023]
Abstract
Plants growing in nature often experience fluctuating irradiance. However, in the laboratory, the dynamics of photosynthesis are usually explored by instantaneously exposing dark-adapted plants to constant light and examining the dark-to-light transition, which is a poor approximation of natural phenomena. With the aim creating a better approximation, we exposed leaves of pea (Pisum sativum) to oscillating light and measured changes in the functioning of PSI and PSII, and of the proton motive force at the thylakoid membrane. We found that the dynamics depended on the oscillation period, revealing information about the underlying regulatory networks. As demonstrated for a selected oscillation period of 60 s, the regulation tries to keep the reaction centers of PSI and PSII open. We present an evaluation of the data obtained, and discuss the involvement of particular processes in the regulation of photosynthesis. The forced oscillations provided an information-rich fingerprint of complex regulatory networks. We expect future progress in understanding these networks from experiments involving chemical interventions and plant mutants, and by using mathematical modeling and systems identification and control tools.
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Affiliation(s)
- Dušan Lazár
- Department of Biophysics, Faculty of Science, Palacký University, Šlechtitelů 27, 783 71 Olomouc, Czech Republic
| | - Yuxi Niu
- Institute of Bio- and Geosciences/Plant Sciences (IBG-2), Forschungszentrum Jülich, Wilhelm-Johnen-Straße, D-52428 Jülich, Germany
| | - Ladislav Nedbal
- Department of Biophysics, Faculty of Science, Palacký University, Šlechtitelů 27, 783 71 Olomouc, Czech Republic
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17
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Romero E. Surviving on low-energy light comes at a price. eLife 2022; 11:82221. [PMID: 36053269 PMCID: PMC9439676 DOI: 10.7554/elife.82221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Two species of photosynthetic cyanobacteria can thrive in far-red light but they either become less resilient to photodamage or less energy efficient.
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Affiliation(s)
- Elisabet Romero
- Institute of Chemical Research of Catalonia, The Barcelona Institute of Science and Technology, Tarragona, Spain
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18
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Lyu H, Lazár D. Analyzing the effect of ion binding to the membrane-surface on regulating the light-induced transthylakoid electric potential (ΔΨ m). FRONTIERS IN PLANT SCIENCE 2022; 13:945675. [PMID: 35968094 PMCID: PMC9366520 DOI: 10.3389/fpls.2022.945675] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 06/28/2022] [Indexed: 06/15/2023]
Abstract
The transthylakoid membrane potential (ΔΨm) is essential because it can drive the ATP synthesis through the CF0-CF1 type of ATP-synthase in chloroplasts as an energetic equivalent similar to ΔpH. In addition, a high fraction of proton motive force (PMF) stored as the ΔΨm component is physiologically important in the acclimation of photosynthesis to environmental stresses. It has been shown that ΔΨm is the sum of the Donnan potential difference (ΔΨdn) and the diffusion potential difference (ΔΨd). Specifically, ΔΨdn, ΔΨd, and ΔΨm are strongly associated with the ionic activities near the membrane surface, particularly, the extent of ion binding to the charged/neutral sites adjacent to the membrane surface. However, an in-depth analysis of the effect of altered cationic binding to the membrane surface on adjusting the transthylakoid electric potentials (ΔΨdn, ΔΨd, and ΔΨm) is still missing. This lack of a mechanistic understanding is due to the experimental difficulty of closely observing cations binding to the membrane surface in vivo. In this work, a computer model was proposed to investigate the transthylakoid electric phenomena in the chloroplast focusing on the interaction between cations and the negative charges close to the membrane surface. By employing the model, we simulated the membrane potential and consequently, the measured ECS traces, proxing the ΔΨm, were well described by the computing results on continuous illumination followed by a dark-adapted period. Moreover, the computing data clarified the components of transthylakoid membrane potential, unraveled the functional consequences of altered cationic attachment to the membrane surface on adjusting the transthylakoid electric potential, and further revealed the key role played by Donnan potential in regulating the energization of the thylakoid membrane. The current model for calculating electric potentials can function as a preliminary network for the further development into a more detailed theoretical model by which multiple important variables involved in photosynthesis can be explored.
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Affiliation(s)
- Hui Lyu
- School of Biological Science and Agriculture, Qiannan Normal University for Nationalities, Duyun, China
| | - Dušan Lazár
- Department of Biophysics, Faculty of Science, Palacký University, Olomouc, Czechia
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19
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Lopez LS, Völkner C, Day PM, Lewis CM, Lewis CL, Schneider D, Correa Galvis V, Cruz JA, Armbruster U, Kramer DM, Kunz H. The Arabidopsis T-DNA mutant SALK_008491 carries a 14-kb deletion on chromosome 3 that provides rare insights into the plant response to dynamic light stress. PLANT DIRECT 2022; 6:e429. [PMID: 35875836 PMCID: PMC9300446 DOI: 10.1002/pld3.429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 06/25/2022] [Accepted: 07/01/2022] [Indexed: 05/14/2023]
Abstract
In nature, plants experience rapid changes in light intensity and quality throughout the day. To maximize growth, they have established molecular mechanisms to optimize photosynthetic output while protecting components of the light-dependent reaction and CO2 fixation pathways. Plant phenotyping of mutant collections has become a powerful tool to unveil the genetic loci involved in environmental acclimation. Here, we describe the phenotyping of the transfer-DNA (T-DNA) insertion mutant line SALK_008491, previously known as nhd1-1. Growth in a fluctuating light regime caused a loss in growth rate accompanied by a spike in photosystem (PS) II damage and increased non-photochemical quenching (NPQ). Interestingly, an independent nhd1 null allele did not recapitulate the NPQ phenotype. Through bulk sequencing of a backcrossed segregating F2 pool, we identified an ~14-kb large deletion on chromosome 3 (Chr3) in SALK_008491 affecting five genes upstream of NHD1. Besides NHD1, which encodes for a putative plastid Na+/H+ antiporter, the stromal NAD-dependent D-3-phosphoglycerate dehydrogenase 3 (PGDH3) locus was eradicated. Although some changes in the SALK_008491 mutant's photosynthesis can be assigned to the loss of PGDH3, our follow-up studies employing respective single mutants and complementation with overlapping transformation-competent artificial chromosome (TAC) vectors reveal that the exacerbated fluctuating light sensitivity in SALK_008491 mutants result from the simultaneous loss of PGDH3 and NHD1. Altogether, the data obtained from this large deletion-carrying mutant provide new and unintuitive insights into the molecular mechanisms that function to protect the photosynthetic machinery. Moreover, our study renews calls for caution when setting up reverse genetic studies using T-DNA lines. Although second-site insertions, indels, and SNPs have been reported before, large deletion surrounding the insertion site causes yet another problem. Nevertheless, as shown through this research, such unpredictable genetic events following T-DNA mutagenesis can provide unintuitive insights that allow for understanding complex phenomena such as the plant acclimation to dynamic high light stress.
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Affiliation(s)
- Laura S. Lopez
- School of Biological SciencesWashington State UniversityPullmanWashington
| | - Carsten Völkner
- School of Biological SciencesWashington State UniversityPullmanWashington
- Department of Plant BiochemistryLMU MunichPlanegg‐MartinsriedGermany
| | - Philip M. Day
- School of Biological SciencesWashington State UniversityPullmanWashington
| | - Chance M. Lewis
- School of Biological SciencesWashington State UniversityPullmanWashington
| | - Chase L. Lewis
- School of Biological SciencesWashington State UniversityPullmanWashington
| | - Dominik Schneider
- Compact Plants Phenomics CenterWashington State UniversityPullmanWashingtonUSA
| | | | - Jeffrey A. Cruz
- Department of Biochemistry and Molecular BiologyMichigan State UniversityEast LansingMichiganUSA
- Department of Energy Plant Research LaboratoryMichigan State UniversityEast LansingMichiganUSA
| | - Ute Armbruster
- Max Planck Institute of Molecular Plant PhysiologyPotsdamGermany
| | - David M. Kramer
- Department of Biochemistry and Molecular BiologyMichigan State UniversityEast LansingMichiganUSA
- Department of Energy Plant Research LaboratoryMichigan State UniversityEast LansingMichiganUSA
| | - Hans‐Henning Kunz
- School of Biological SciencesWashington State UniversityPullmanWashington
- Department of Plant BiochemistryLMU MunichPlanegg‐MartinsriedGermany
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20
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Long SP, Taylor SH, Burgess SJ, Carmo-Silva E, Lawson T, De Souza AP, Leonelli L, Wang Y. Into the Shadows and Back into Sunlight: Photosynthesis in Fluctuating Light. ANNUAL REVIEW OF PLANT BIOLOGY 2022; 73:617-648. [PMID: 35595290 DOI: 10.1146/annurev-arplant-070221-024745] [Citation(s) in RCA: 48] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Photosynthesis is an important remaining opportunity for further improvement in the genetic yield potential of our major crops. Measurement, analysis, and improvement of leaf CO2 assimilation (A) have focused largely on photosynthetic rates under light-saturated steady-state conditions. However, in modern crop canopies of several leaf layers, light is rarely constant, and the majority of leaves experience marked light fluctuations throughout the day. It takes several minutes for photosynthesis to regain efficiency in both sun-shade and shade-sun transitions, costing a calculated 10-40% of potential crop CO2 assimilation. Transgenic manipulations to accelerate the adjustment in sun-shade transitions have already shown a substantial productivity increase in field trials. Here, we explore means to further accelerate these adjustments and minimize these losses through transgenic manipulation, gene editing, and exploitation of natural variation. Measurement andanalysis of photosynthesis in sun-shade and shade-sun transitions are explained. Factors limiting speeds of adjustment and how they could be modified to effect improved efficiency are reviewed, specifically nonphotochemical quenching (NPQ), Rubisco activation, and stomatal responses.
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Affiliation(s)
- Stephen P Long
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA;
- Departments of Plant Biology and Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Lancaster Environment Centre, Lancaster University, Lancaster, United Kingdom
| | - Samuel H Taylor
- Lancaster Environment Centre, Lancaster University, Lancaster, United Kingdom
| | - Steven J Burgess
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA;
| | | | - Tracy Lawson
- School of Life Sciences, University of Essex, Colchester, United Kingdom
| | - Amanda P De Souza
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA;
| | - Lauriebeth Leonelli
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA;
- Department of Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Yu Wang
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA;
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21
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Zuo G, Aiken RM, Feng N, Zheng D, Zhao H, Avenson TJ, Lin X. Fresh perspectives on an established technique: Pulsed amplitude modulation chlorophyll a fluorescence. PLANT-ENVIRONMENT INTERACTIONS (HOBOKEN, N.J.) 2022; 3:41-59. [PMID: 37284008 PMCID: PMC10168060 DOI: 10.1002/pei3.10073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Revised: 02/22/2022] [Accepted: 02/25/2022] [Indexed: 06/08/2023]
Abstract
Pulsed amplitude modulation (PAM) chlorophyll a fluorescence provides information about photosynthetic energy transduction. When reliably measured, chlorophyll a fluorescence provides detailed information about critical in vivo photosynthetic processes. Such information has recently provided novel and critical insights into how the yield potential of crops can be improved and it is being used to understand remotely sensed fluorescence, which is termed solar-induced fluorescence and will be solely measured by a satellite scheduled to be launched this year. While PAM chlorophyll a fluorometers measure fluorescence intensity per se, herein we articulate the axiomatic criteria by which instrumentally detected intensities can be assumed to assess fluorescence yield, a phenomenon quite different than fluorescence intensity and one that provides critical insight about how solar energy is variably partitioned into the biosphere. An integrated mathematical, phenomenological, and practical discussion of many useful chlorophyll a fluorescence parameters is presented. We draw attention to, and provide examples of, potential uncertainties that can result from incorrect methodological practices and potentially problematic instrumental design features. Fundamentals of fluorescence measurements are discussed, including the major assumptions underlying the signals and the methodological caveats about taking measurements during both dark- and light-adapted conditions. Key fluorescence parameters are discussed in the context of recent applications under environmental stress. Nuanced information that can be gleaned from intra-comparisons of fluorescence-derived parameters and intercomparisons of fluorescence-derived parameters with those based on other techniques is elucidated.
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Affiliation(s)
- Guanqiang Zuo
- Department of AgronomyKansas State UniversityManhattanKansasUSA
| | - Robert M. Aiken
- Department of AgronomyKansas State UniversityManhattanKansasUSA
- Northwest Research‐Extension CenterKansas State UniversityColbyKansasUSA
| | - Naijie Feng
- College of Coastal Agricultural ScienceGuangdong Ocean UniversityZhanjiangChina
- Shenzhen Research Institute of Guangdong Ocean UniversityShenzhenChina
| | - Dianfeng Zheng
- College of Coastal Agricultural ScienceGuangdong Ocean UniversityZhanjiangChina
- Shenzhen Research Institute of Guangdong Ocean UniversityShenzhenChina
| | - Haidong Zhao
- Department of AgronomyKansas State UniversityManhattanKansasUSA
| | | | - Xiaomao Lin
- Department of AgronomyKansas State UniversityManhattanKansasUSA
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22
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Trinh MDL, Masuda S. Chloroplast pH Homeostasis for the Regulation of Photosynthesis. FRONTIERS IN PLANT SCIENCE 2022; 13:919896. [PMID: 35693183 PMCID: PMC9174948 DOI: 10.3389/fpls.2022.919896] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 05/04/2022] [Indexed: 05/16/2023]
Abstract
The pH of various chloroplast compartments, such as the thylakoid lumen and stroma, is light-dependent. Light illumination induces electron transfer in the photosynthetic apparatus, coupled with proton translocation across the thylakoid membranes, resulting in acidification and alkalization of the thylakoid lumen and stroma, respectively. Luminal acidification is crucial for inducing regulatory mechanisms that protect photosystems against photodamage caused by the overproduction of reactive oxygen species (ROS). Stromal alkalization activates enzymes involved in the Calvin-Benson-Bassham (CBB) cycle. Moreover, proton translocation across the thylakoid membranes generates a proton gradient (ΔpH) and an electric potential (ΔΨ), both of which comprise the proton motive force (pmf) that drives ATP synthase. Then, the synthesized ATP is consumed in the CBB cycle and other chloroplast metabolic pathways. In the dark, the pH of both the chloroplast stroma and thylakoid lumen becomes neutral. Despite extensive studies of the above-mentioned processes, the molecular mechanisms of how chloroplast pH can be maintained at proper levels during the light phase for efficient activation of photosynthesis and other metabolic pathways and return to neutral levels during the dark phase remain largely unclear, especially in terms of the precise control of stromal pH. The transient increase and decrease in chloroplast pH upon dark-to-light and light-to-dark transitions have been considered as signals for controlling other biological processes in plant cells. Forward and reverse genetic screening approaches recently identified new plastid proteins involved in controlling ΔpH and ΔΨ across the thylakoid membranes and chloroplast proton/ion homeostasis. These proteins have been conserved during the evolution of oxygenic phototrophs and include putative photosynthetic protein complexes, proton transporters, and/or their regulators. Herein, we summarize the recently identified protein players that control chloroplast pH and influence photosynthetic efficiency in plants.
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Affiliation(s)
- Mai Duy Luu Trinh
- Department of Plant and Environmental Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Shinji Masuda
- Department of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
- *Correspondence: Shinji Masuda,
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23
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Viola S, Roseby W, Santabarbara S, Nürnberg D, Assunção R, Dau H, Sellés J, Boussac A, Fantuzzi A, Rutherford AW. Impact of energy limitations on function and resilience in long-wavelength Photosystem II. eLife 2022; 11:79890. [PMID: 35852834 PMCID: PMC9439682 DOI: 10.7554/elife.79890] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Accepted: 07/18/2022] [Indexed: 01/06/2023] Open
Abstract
Photosystem II (PSII) uses the energy from red light to split water and reduce quinone, an energy-demanding process based on chlorophyll a (Chl-a) photochemistry. Two types of cyanobacterial PSII can use chlorophyll d (Chl-d) and chlorophyll f (Chl-f) to perform the same reactions using lower energy, far-red light. PSII from Acaryochloris marina has Chl-d replacing all but one of its 35 Chl-a, while PSII from Chroococcidiopsis thermalis, a facultative far-red species, has just 4 Chl-f and 1 Chl-d and 30 Chl-a. From bioenergetic considerations, the far-red PSII were predicted to lose photochemical efficiency and/or resilience to photodamage. Here, we compare enzyme turnover efficiency, forward electron transfer, back-reactions and photodamage in Chl-f-PSII, Chl-d-PSII, and Chl-a-PSII. We show that: (i) all types of PSII have a comparable efficiency in enzyme turnover; (ii) the modified energy gaps on the acceptor side of Chl-d-PSII favour recombination via PD1+Phe- repopulation, leading to increased singlet oxygen production and greater sensitivity to high-light damage compared to Chl-a-PSII and Chl-f-PSII; (iii) the acceptor-side energy gaps in Chl-f-PSII are tuned to avoid harmful back reactions, favouring resilience to photodamage over efficiency of light usage. The results are explained by the differences in the redox tuning of the electron transfer cofactors Phe and QA and in the number and layout of the chlorophylls that share the excitation energy with the primary electron donor. PSII has adapted to lower energy in two distinct ways, each appropriate for its specific environment but with different functional penalties.
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Affiliation(s)
- Stefania Viola
- Department of Life Sciences, Imperial College LondonLondonUnited Kingdom
| | - William Roseby
- Department of Life Sciences, Imperial College LondonLondonUnited Kingdom
| | | | | | | | - Holger Dau
- Physics Department, Freie Universität BerlinBerlinGermany
| | - Julien Sellés
- Institut de Biologie Physico-Chimique, UMR CNRS 7141 and Sorbonne UniversitéParisFrance
| | - Alain Boussac
- Institut de Biologie Intégrative de la Cellule, UMR9198, CEA SaclayGif-Sur-YvetteFrance
| | - Andrea Fantuzzi
- Department of Life Sciences, Imperial College LondonLondonUnited Kingdom
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24
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Uflewski M, Mielke S, Correa Galvis V, von Bismarck T, Chen X, Tietz E, Ruß J, Luzarowski M, Sokolowska E, Skirycz A, Eirich J, Finkemeier I, Schöttler MA, Armbruster U. Functional characterization of proton antiport regulation in the thylakoid membrane. PLANT PHYSIOLOGY 2021; 187:2209-2229. [PMID: 33742682 PMCID: PMC8644300 DOI: 10.1093/plphys/kiab135] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 03/03/2021] [Indexed: 05/21/2023]
Abstract
During photosynthesis, energy is transiently stored as an electrochemical proton gradient across the thylakoid membrane. The resulting proton motive force (pmf) is composed of a membrane potential (ΔΨ) and a proton concentration gradient (ΔpH) and powers the synthesis of ATP. Light energy availability for photosynthesis can change very rapidly and frequently in nature. Thylakoid ion transport proteins buffer the effects that light fluctuations have on photosynthesis by adjusting pmf and its composition. Ion channel activities dissipate ΔΨ, thereby reducing charge recombinations within photosystem II. The dissipation of ΔΨ allows for increased accumulation of protons in the thylakoid lumen, generating the signal that activates feedback downregulation of photosynthesis. Proton export from the lumen via the thylakoid K+ exchange antiporter 3 (KEA3), instead, decreases the ΔpH fraction of the pmf and thereby reduces the regulatory feedback signal. Here, we reveal that the Arabidopsis (Arabidopsis thaliana) KEA3 protein homo-dimerizes via its C-terminal domain. This C-terminus has a regulatory function, which responds to light intensity transients. Plants carrying a C-terminus-less KEA3 variant show reduced feed-back downregulation of photosynthesis and suffer from increased photosystem damage under long-term high light stress. However, during photosynthetic induction in high light, KEA3 deregulation leads to an increase in carbon fixation rates. Together, the data reveal a trade-off between long-term photoprotection and a short-term boost in carbon fixation rates, which is under the control of the KEA3 C-terminus.
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Affiliation(s)
- Michał Uflewski
- Max Planck Institute of Molecular Plant Physiology, Potsdam 14476, Germany
| | - Sarah Mielke
- Max Planck Institute of Molecular Plant Physiology, Potsdam 14476, Germany
| | | | | | - Xiaoheng Chen
- Max Planck Institute of Molecular Plant Physiology, Potsdam 14476, Germany
| | - Enrico Tietz
- Max Planck Institute of Molecular Plant Physiology, Potsdam 14476, Germany
| | - Jeremy Ruß
- Max Planck Institute of Molecular Plant Physiology, Potsdam 14476, Germany
| | - Marcin Luzarowski
- Max Planck Institute of Molecular Plant Physiology, Potsdam 14476, Germany
| | - Ewelina Sokolowska
- Max Planck Institute of Molecular Plant Physiology, Potsdam 14476, Germany
| | - Aleksandra Skirycz
- Max Planck Institute of Molecular Plant Physiology, Potsdam 14476, Germany
- Boyce Thompson Institute, Ithaca 14853, New York
| | - Jürgen Eirich
- Plant Physiology, Institute of Plant Biology and Biotechnology, University of Münster, Münster 48149, Germany
| | - Iris Finkemeier
- Plant Physiology, Institute of Plant Biology and Biotechnology, University of Münster, Münster 48149, Germany
| | | | - Ute Armbruster
- Max Planck Institute of Molecular Plant Physiology, Potsdam 14476, Germany
- Author for communication:
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25
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Kanazawa A, Chattopadhyay A, Kuhlgert S, Tuitupou H, Maiti T, Kramer DM. Light potentials of photosynthetic energy storage in the field: what limits the ability to use or dissipate rapidly increased light energy? ROYAL SOCIETY OPEN SCIENCE 2021; 8:211102. [PMID: 34925868 PMCID: PMC8672073 DOI: 10.1098/rsos.211102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 11/08/2021] [Indexed: 06/14/2023]
Abstract
The responses of plant photosynthesis to rapid fluctuations in environmental conditions are critical for efficient conversion of light energy. These responses are not well-seen laboratory conditions and are difficult to probe in field environments. We demonstrate an open science approach to this problem that combines multifaceted measurements of photosynthesis and environmental conditions, and an unsupervised statistical clustering approach. In a selected set of data on mint (Mentha sp.), we show that 'light potentials' for linear electron flow and non-photochemical quenching (NPQ) upon rapid light increases are strongly suppressed in leaves previously exposed to low ambient photosynthetically active radiation (PAR) or low leaf temperatures, factors that can act both independently and cooperatively. Further analyses allowed us to test specific mechanisms. With decreasing leaf temperature or PAR, limitations to photosynthesis during high light fluctuations shifted from rapidly induced NPQ to photosynthetic control of electron flow at the cytochrome b6f complex. At low temperatures, high light induced lumen acidification, but did not induce NPQ, leading to accumulation of reduced electron transfer intermediates, probably inducing photodamage, revealing a potential target for improving the efficiency and robustness of photosynthesis. We discuss the implications of the approach for open science efforts to understand and improve crop productivity.
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Affiliation(s)
- Atsuko Kanazawa
- MSU-DOE Plant Research Lab, Michigan State University, East Lansing, MI 48824, USA
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - Abhijnan Chattopadhyay
- MSU-DOE Plant Research Lab, Michigan State University, East Lansing, MI 48824, USA
- Department of Statistics and Probability, Michigan State University, East Lansing, MI 48824, USA
| | - Sebastian Kuhlgert
- MSU-DOE Plant Research Lab, Michigan State University, East Lansing, MI 48824, USA
| | - Hainite Tuitupou
- MSU-DOE Plant Research Lab, Michigan State University, East Lansing, MI 48824, USA
| | - Tapabrata Maiti
- Department of Statistics and Probability, Michigan State University, East Lansing, MI 48824, USA
| | - David M. Kramer
- MSU-DOE Plant Research Lab, Michigan State University, East Lansing, MI 48824, USA
- Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
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26
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Chovancek E, Zivcak M, Brestic M, Hussain S, Allakhverdiev SI. The different patterns of post-heat stress responses in wheat genotypes: the role of the transthylakoid proton gradient in efficient recovery of leaf photosynthetic capacity. PHOTOSYNTHESIS RESEARCH 2021; 150:179-193. [PMID: 33393064 DOI: 10.1007/s11120-020-00812-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 12/08/2020] [Indexed: 05/28/2023]
Abstract
The frequency and severity of heat waves are expected to increase in the near future, with a significant impact on physiological functions and yield of crop plants. In this study, we assessed the residual post-heat stress effects on photosynthetic responses of six diverse winter wheat (Triticum sp.) genotypes, differing in country of origin, taxonomy and ploidy (tetraploids vs. hexaploids). After 5 days of elevated temperatures (up to 38 °C), the photosynthetic parameters recorded on the first day of recovery (R1) as well as after the next 4-5 days of the recovery (R2) were compared to those of the control plants (C) grown under moderate temperatures. Based on the values of CO2 assimilation rate (A) and the maximum rates of carboxylation (VCmax) in R1, we identified that the hexaploid (HEX) and tetraploid (TET) species clearly differed in the strength of their response to heat stress. Next, the analyses of gas exchange, simultaneous measurements of PSI and PSII photochemistry and the measurements of electrochromic bandshift (ECS) have consistently shown that photosynthetic and photoprotective functions in leaves of TET genotypes were almost fully recovered in R2, whereas the recovery of photosynthetic and photoprotective functions in the HEX group in R2 was still rather low. A poor recovery was associated with an overly reduced acceptor side of photosystem I as well as high values of the electric membrane potential (Δψ component of the proton motive force, pmf) in the chloroplast. On the other hand, a good recovery of photosynthetic capacity and photoprotective functions was clearly associated with an enhanced ΔpH component of the pmf, thus demonstrating a key role of efficient regulation of proton transport to ensure buildup of the transthylakoid proton gradient needed for photosynthesis restoration after high-temperature episodes.
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Affiliation(s)
- Erik Chovancek
- Department of Plant Physiology, Slovak University of Agriculture, Nitra, Slovak Republic
| | - Marek Zivcak
- Department of Plant Physiology, Slovak University of Agriculture, Nitra, Slovak Republic.
| | - Marian Brestic
- Department of Plant Physiology, Slovak University of Agriculture, Nitra, Slovak Republic
| | - Sajad Hussain
- College of Agronomy, Sichuan Agricultural University, Chengdu, People's Republic of China
- Sichuan Engineering Research Center for Crop Strip Intercropping System, Key Laboratory of Crop Ecophysiology and Farming System in Southwest China, Sichuan Agricultural University, Chengdu, People's Republic of China
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27
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Li H, Yang M, Zhao C, Wang Y, Zhang R. Physiological and proteomic analyses revealed the response mechanisms of two different drought-resistant maize varieties. BMC PLANT BIOLOGY 2021; 21:513. [PMID: 34736392 PMCID: PMC8567644 DOI: 10.1186/s12870-021-03295-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 10/26/2021] [Indexed: 05/05/2023]
Abstract
BACKGROUND Drought stress severely limits maize seedling growth and crop yield. Previous studies have elucidated the mechanisms by which maize acquires drought resistance and contends with water deficiency. However, the link between the physiological and molecular variations among maize cultivars are unknown. Here, physiological and proteomic analyses were conducted to compare the stress responses of two maize cultivars with contrasting drought stress tolerance. RESULTS The physiological analysis showed that the drought-tolerant SD609 maize variety maintains relatively high photochemical efficiency by enhancing its protective cyclic electron flow (CEF) mechanism and antioxidative enzymes activities. Proteomics analysis revealed that 198 and 102 proteins were differentially expressed in SD609 and the drought-sensitive SD902 cultivar, respectively. GO and KEGG enrichments indicated that SD609 upregulated proteins associated with photosynthesis, antioxidants/detoxifying enzymes, molecular chaperones and metabolic enzymes. Upregulation of the proteins related to PSII repair and photoprotection improved photochemical capacity in SD609 subjected to moderate drought stress. In SD902, however, only the molecular chaperones and sucrose synthesis pathways were induced and they failed to protect the impaired photosystem. Further analysis demonstrated that proteins related to the electron transport chain (ETC) and redox homeostasis as well as heat shock proteins (HSPs) may be important in protecting plants from drought stress. CONCLUSIONS Our experiments explored the mechanism of drought tolerance and clarified the interconnections between the physiological and proteomic factors contributing to it. In summary, our findings aid in further understanding of the drought tolerance mechanisms in maize.
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Affiliation(s)
- Hongjie Li
- College of Agronomy, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Mei Yang
- College of Agronomy, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Chengfeng Zhao
- College of Agronomy, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Yifan Wang
- College of Agronomy, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Renhe Zhang
- College of Agronomy, Northwest A&F University, Yangling, 712100, Shaanxi, China.
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28
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Yang YJ, Sun H, Zhang SB, Huang W. Roles of alternative electron flows in response to excess light in Ginkgo biloba. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2021; 312:111030. [PMID: 34620434 DOI: 10.1016/j.plantsci.2021.111030] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 08/17/2021] [Accepted: 08/20/2021] [Indexed: 06/13/2023]
Abstract
Ginkgo biloba L., the only surviving species of Ginkgoopsida, is a famous relict gymnosperm, it may provide new insight into the evolution of photosynthetic mechanisms. Flavodiiron proteins (FDPs) are conserved in nonflowering plants, but the role of FDPs in gymnosperms has not yet been clarified. In particular, how gymnosperms integrate FDPs and cyclic electron transport (CET) to better adapt to excess light is poorly understood. To elucidate these questions, we measured the P700 signal, chlorophyll fluorescence and electrochromic shift signal under fluctuating and constant light in G. biloba. Within the first seconds after light increased, G. biloba could not build up a sufficient proton gradient (ΔpH). Concomitantly, photo-reduction of O2 mediated by FDPs contributed to the rapid oxidation of P700 and protected PSI under fluctuating light. Therefore, in G. biloba, FDPs mainly protect PSI under fluctuating light at acceptor side. Under constant high light, the oxidation of PSI and the induction of non-photochemical quenching were attributed to the increase in ΔpH formation, which was mainly caused by the increase in CET rather than linear electron transport. Therefore, under constant light, CET finely regulates the PSI redox state and non-photochemical quenching through ΔpH formation, protecting PSI and PSII against excess light. We conclude that, in G. biloba, FDPs are particularly important under fluctuating light while CET is essential under constant high light. The coordination of FDPs and CET fine-tune photosynthetic apparatus under excess light.
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Affiliation(s)
- Ying-Jie Yang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Hu Sun
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shi-Bao Zhang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China
| | - Wei Huang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China.
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29
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Wilson S, Johnson MP, Ruban AV. Proton motive force in plant photosynthesis dominated by ΔpH in both low and high light. PLANT PHYSIOLOGY 2021; 187:263-275. [PMID: 34618143 PMCID: PMC8418402 DOI: 10.1093/plphys/kiab270] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 05/23/2021] [Indexed: 05/08/2023]
Abstract
The proton motive force (pmf) across the thylakoid membrane couples photosynthetic electron transport and ATP synthesis. In recent years, the electrochromic carotenoid and chlorophyll absorption band shift (ECS), peaking ∼515 nm, has become a widely used probe to measure pmf in leaves. However, the use of this technique to calculate the parsing of the pmf between the proton gradient (ΔpH) and electric potential (Δψ) components remains controversial. Interpretation of the ECS signal is complicated by overlapping absorption changes associated with violaxanthin de-epoxidation to zeaxanthin (ΔA505) and energy-dependent nonphotochemical quenching (qE; ΔA535). In this study, we used Arabidopsis (Arabidopsis thaliana) plants with altered xanthophyll cycle activity and photosystem II subunit S (PsbS) content to disentangle these overlapping contributions. In plants where overlap among ΔA505, ΔA535, and ECS is diminished, such as npq4 (lacking ΔA535) and npq1npq4 (also lacking ΔA505), the parsing method implies the Δψ contribution is virtually absent and pmf is solely composed of ΔpH. Conversely, in plants where ΔA535 and ECS overlap is enhanced, such as L17 (a PsbS overexpressor) and npq1 (where ΔA535 is blue-shifted to 525 nm) the parsing method implies a dominant contribution of Δψ to the total pmf. These results demonstrate the vast majority of the pmf attributed by the ECS parsing method to Δψ is caused by ΔA505 and ΔA535 overlap, confirming pmf is dominated by ΔpH following the first 60 s of continuous illumination under both low and high light conditions. Further implications of these findings for the regulation of photosynthesis are discussed.
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Affiliation(s)
- Sam Wilson
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Matthew P. Johnson
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, UK
| | - Alexander V. Ruban
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
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30
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Zavafer A. A theoretical framework of the hybrid mechanism of photosystem II photodamage. PHOTOSYNTHESIS RESEARCH 2021; 149:107-120. [PMID: 34338941 DOI: 10.1007/s11120-021-00843-1] [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: 08/13/2020] [Accepted: 05/04/2021] [Indexed: 06/13/2023]
Abstract
Photodamage of photosystem II is a significant physiological process that is prevalent in the fields of photobiology, photosynthesis research and plant/algal stress. Since its discovery, numerous efforts have been devoted to determine the causes and mechanisms of action of photosystem II photodamage. There are two contrasting hypotheses to explain photodamage: (1) the excitation pressure induced by light absorption by the photosynthetic pigments and (2) direct photodamage of the Mn cluster located at the water-splitting site, which is independent of excitation pressure. While these two hypotheses seemed mutually exclusive, during the last decade, several independent works have proposed an alternative approach indicating that both hypotheses are valid. This was termed the dual hypothesis of photosystem II photodamage, and it postulates that both excess excitation and direct Mn photodamage operate at the same time, independently or in a synergic manner, depending on the type of sample, temperature, light spectrum, or other environmental stressors. In this mini-review, a brief summary of the contrasting hypotheses is presented, followed by recapitulation of key discoveries in the field of photosystem II photodamage of the last decade, and a synthesis of how these works support a full hybrid framework (operation of several mechanisms and their permutations) to explain PSII photodamage. All these are in recognition of Prof. Wah Soon Chow (the Australian National University), one of the key proposers of the dual hypothesis.
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Affiliation(s)
- Alonso Zavafer
- Research School of Biology, Australian National University, Canberra, ACT, 2600, Australia.
- Climate Change Cluster (C3), University of Technology Sydney, Sydney, NSW, 2007, Australia.
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31
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Dmitrieva VA, Domashkina VV, Ivanova AN, Sukhov VS, Tyutereva EV, Voitsekhovskaja OV. Regulation of plasmodesmata in Arabidopsis leaves: ATP, NADPH and chlorophyll b levels matter. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:5534-5552. [PMID: 33974689 DOI: 10.1093/jxb/erab205] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 05/07/2021] [Indexed: 06/12/2023]
Abstract
In mature leaves, cell-to-cell transport via plasmodesmata between mesophyll cells links the production of assimilates by photosynthesis with their export to sink organs. This study addresses the question of how signals derived from chloroplasts and photosynthesis influence plasmodesmata permeability. Cell-to-cell transport was analyzed in leaves of the Arabidopsis chlorophyll b-less ch1-3 mutant, the same mutant complemented with a cyanobacterial CAO gene (PhCAO) overaccumulating chlorophyll b, the trxm3 mutant lacking plastidial thioredoxin m3, and the ntrc mutant lacking functional NADPH:thioredoxin reductase C. The regulation of plasmodesmata permeability in these lines could not be traced back to the reduction state of the thioredoxin system or the types and levels of reactive oxygen species produced in chloroplasts; however, it could be related to chloroplast ATP and NADPH production. The results suggest that light enables plasmodesmata closure via an increase in the ATP and NADPH levels produced in photosynthesis, providing a control mechanism for assimilate export based on the rate of photosynthate production in the Calvin-Benson cycle. The level of chlorophyll b influences plasmodesmata permeability via as-yet-unidentified signals. The data also suggest a role of thioredoxin m3 in the regulation of cyclic electron flow around photosystem I.
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Affiliation(s)
- Valeria A Dmitrieva
- Laboratory of Molecular and Ecological Physiology, Komarov Botanical Institute, Russian Academy of Sciences, St. Petersburg, Russia
| | - Valentina V Domashkina
- Laboratory of Molecular and Ecological Physiology, Komarov Botanical Institute, Russian Academy of Sciences, St. Petersburg, Russia
| | - Alexandra N Ivanova
- Laboratory of Plant Anatomy, Komarov Botanical Institute, Russian Academy of Sciences, St. Petersburg, Russia
- Research Park, St. Petersburg State University, St. Petersburg, Russia
| | - Vladimir S Sukhov
- Department of Biophysics, N.I. Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, Russia
| | - Elena V Tyutereva
- Laboratory of Molecular and Ecological Physiology, Komarov Botanical Institute, Russian Academy of Sciences, St. Petersburg, Russia
| | - Olga V Voitsekhovskaja
- Laboratory of Molecular and Ecological Physiology, Komarov Botanical Institute, Russian Academy of Sciences, St. Petersburg, Russia
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32
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Cruz JA, Avenson TJ. Photosynthesis: a multiscopic view. JOURNAL OF PLANT RESEARCH 2021; 134:665-682. [PMID: 34170422 DOI: 10.1007/s10265-021-01321-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 06/11/2021] [Indexed: 06/13/2023]
Abstract
A recurring analogy for photosynthesis research is the fable of the blind men and the elephant. Photosynthesis has many complex working parts, which has driven the need to study each of them individually, with an inherent understanding that a more complete picture will require systematic integration of these views. However, unlike the blind men, who are limited to using their hands, researchers have developed over the past decades a repertoire of methods for studying these components, many of which capitalize on unique features intrinsic to each. More recent concerns about food security and clean, renewable energy have increased support for applied photosynthesis research, with the idea of either improving photosynthetic performance as a desired trait in select species or using photosynthetic measurements as a phenotyping tool in breeding efforts or for high precision crop management. In this review, we spotlight the migration of approaches for studying photosynthesis from the laboratory into field environments, highlight some recent advances and speculate on areas where further development would be fruitful, with an eye towards how applied photosynthesis research can have impacts at local and global scales.
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Affiliation(s)
- Jeffrey A Cruz
- Plant Research Laboratories, Michigan State University, 612 Wilson Road, MI, S-206, Lansing, USA.
- Department of Biochemistry and Molecular Biology, Michigan State University, Lansing, MI, USA.
| | - Thomas J Avenson
- Department of Plant Sciences, University of Cambridge, CB2 9EW, Cambridge, UK
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33
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Höhner R, Day PM, Zimmermann SE, Lopez LS, Krämer M, Giavalisco P, Correa Galvis V, Armbruster U, Schöttler MA, Jahns P, Krueger S, Kunz HH. Stromal NADH supplied by PHOSPHOGLYCERATE DEHYDROGENASE3 is crucial for photosynthetic performance. PLANT PHYSIOLOGY 2021; 186:142-167. [PMID: 33779763 PMCID: PMC8154072 DOI: 10.1093/plphys/kiaa117] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 12/17/2020] [Indexed: 05/22/2023]
Abstract
During photosynthesis, electrons travel from light-excited chlorophyll molecules along the electron transport chain to the final electron acceptor nicotinamide adenine dinucleotide phosphate (NADP) to form NADPH, which fuels the Calvin-Benson-Bassham cycle (CBBC). To allow photosynthetic reactions to occur flawlessly, a constant resupply of the acceptor NADP is mandatory. Several known stromal mechanisms aid in balancing the redox poise, but none of them utilizes the structurally highly similar coenzyme NAD(H). Using Arabidopsis (Arabidopsis thaliana) as a C3-model, we describe a pathway that employs the stromal enzyme PHOSPHOGLYCERATE DEHYDROGENASE 3 (PGDH3). We showed that PGDH3 exerts high NAD(H)-specificity and is active in photosynthesizing chloroplasts. PGDH3 withdrew its substrate 3-PGA directly from the CBBC. As a result, electrons become diverted from NADPH via the CBBC into the separate NADH redox pool. pgdh3 loss-of-function mutants revealed an overreduced NADP(H) redox pool but a more oxidized plastid NAD(H) pool compared to wild-type plants. As a result, photosystem I acceptor side limitation increased in pgdh3. Furthermore, pgdh3 plants displayed delayed CBBC activation, changes in nonphotochemical quenching, and altered proton motive force partitioning. Our fluctuating light-stress phenotyping data showed progressing photosystem II damage in pgdh3 mutants, emphasizing the significance of PGDH3 for plant performance under natural light environments. In summary, this study reveals an NAD(H)-specific mechanism in the stroma that aids in balancing the chloroplast redox poise. Consequently, the stromal NAD(H) pool may provide a promising target to manipulate plant photosynthesis.
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Affiliation(s)
- Ricarda Höhner
- School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA
| | - Philip M Day
- School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA
| | - Sandra E Zimmermann
- Biocenter University of Cologne, Institute for Plant Science, Cologne 50674, Germany
| | - Laura S Lopez
- School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA
| | - Moritz Krämer
- School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA
| | | | - Viviana Correa Galvis
- Max Planck Institute of Molecular Plant Physiology, Wissenschaftspark Golm, Potsdam 14476, Germany
| | - Ute Armbruster
- Max Planck Institute of Molecular Plant Physiology, Wissenschaftspark Golm, Potsdam 14476, Germany
| | - Mark Aurel Schöttler
- Max Planck Institute of Molecular Plant Physiology, Wissenschaftspark Golm, Potsdam 14476, Germany
| | - Peter Jahns
- Plant Biochemistry, Heinrich-Heine-University Düsseldorf, Düsseldorf D-40225, Germany
| | - Stephan Krueger
- Biocenter University of Cologne, Institute for Plant Science, Cologne 50674, Germany
| | - Hans-Henning Kunz
- School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA
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34
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Buchert F, Bailleul B, Joliot P. Disentangling chloroplast ATP synthase regulation by proton motive force and thiol modulation in Arabidopsis leaves. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2021; 1862:148434. [PMID: 33932368 DOI: 10.1016/j.bbabio.2021.148434] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 04/06/2021] [Accepted: 04/20/2021] [Indexed: 11/29/2022]
Abstract
The chloroplast ATP synthase (CF1Fo) contains a specific feature to the green lineage: a γ-subunit redox domain that contains a cysteine couple which interacts with the torque-transmitting βDELSEED-loop. This thiol modulation equips CF1Fo with an important environmental fine-tuning mechanism. In vitro, disulfide formation in the γ-redox domain slows down the activity of the CF1Fo at low transmembrane electrochemical proton gradient ( [Formula: see text] ), which agrees with its proposed role as chock based on recently solved structure. The γ-dithiol formation at the onset of light is crucial to maximize photosynthetic efficiency since it lowers the [Formula: see text] activation level for ATP synthesis in vitro. Here, we validate these findings in vivo by utilizing absorption spectroscopy in Arabidopsis thaliana. To do so, we monitored the [Formula: see text] present in darkness and identified its mitochondrial sources. By following the fate and components of light-induced extra [Formula: see text] , we estimated the ATP lifetime that lasted up to tens of minutes after long illuminations. Based on the relationship between [Formula: see text] and CF1Fo activity, we conclude that the dithiol configuration in vivo facilitates photosynthesis by driving the same ATP synthesis rate at a significative lower [Formula: see text] than in the γ-disulfide state. The presented in vivo findings are an additional proof of the importance of CF1Fo thiol modulation, reconciling biochemical in vitro studies and structural insights.
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Affiliation(s)
- Felix Buchert
- Laboratory of Chloroplast Biology and Light-Sensing in Microalgae - UMR7141, IBPC, CNRS-Sorbonne Université, Paris, France; Institute of Plant Biology and Biotechnology, University of Münster, Schlossplatz 8, 48143 Münster, Germany.
| | - Benjamin Bailleul
- Laboratory of Chloroplast Biology and Light-Sensing in Microalgae - UMR7141, IBPC, CNRS-Sorbonne Université, Paris, France
| | - Pierre Joliot
- Laboratory of Chloroplast Biology and Light-Sensing in Microalgae - UMR7141, IBPC, CNRS-Sorbonne Université, Paris, France
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PGR5 is required for efficient Q cycle in the cytochrome b6f complex during cyclic electron flow. Biochem J 2020; 477:1631-1650. [PMID: 32267468 DOI: 10.1042/bcj20190914] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 03/23/2020] [Accepted: 04/07/2020] [Indexed: 01/07/2023]
Abstract
Proton gradient regulation 5 (PGR5) is involved in the control of photosynthetic electron transfer, but its mechanistic role is not yet clear. Several models have been proposed to explain phenotypes such as a diminished steady-state proton motive force (pmf) and increased photodamage of photosystem I (PSI). Playing a regulatory role in cyclic electron flow (CEF) around PSI, PGR5 contributes indirectly to PSI protection by enhancing photosynthetic control, which is a pH-dependent down-regulation of electron transfer at the cytochrome b6f complex (b6f). Here, we re-evaluated the role of PGR5 in the green alga Chlamydomonas reinhardtii and conclude that pgr5 possesses a dysfunctional b6f. Our data indicate that the b6f low-potential chain redox activity likely operated in two distinct modes - via the canonical Q cycle during linear electron flow and via an alternative Q cycle during CEF, which allowed efficient oxidation of the low-potential chain in the WT b6f. A switch between the two Q cycle modes was dependent on PGR5 and relied on unknown stromal electron carrier(s), which were a general requirement for b6f activity. In CEF-favoring conditions, the electron transfer bottleneck in pgr5 was the b6f, in which insufficient low-potential chain redox tuning might account for the mutant pmf phenotype. By attributing a ferredoxin-plastoquinone reductase activity to the b6f and investigating a PGR5 cysteine mutant, a current model of CEF is challenged.
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Roach T. LHCSR3-Type NPQ Prevents Photoinhibition and Slowed Growth under Fluctuating Light in Chlamydomonas reinhardtii. PLANTS 2020; 9:plants9111604. [PMID: 33218177 PMCID: PMC7698959 DOI: 10.3390/plants9111604] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 11/05/2020] [Accepted: 11/16/2020] [Indexed: 01/14/2023]
Abstract
Natural light intensities can rise several orders of magnitude over subsecond time spans, posing a major challenge for photosynthesis. Fluctuating light tolerance in the green alga Chlamydomonas reinhardtii requires alternative electron pathways, but the role of nonphotochemical quenching (NPQ) is not known. Here, fluctuating light (10 min actinic light followed by 10 min darkness) led to significant increase in NPQ/qE-related proteins, LHCSR1 and LHCSR3, relative to constant light of the same subsaturating or saturating intensity. Elevated levels of LHCSR1/3 increased the ability of cells to safely dissipate excess light energy to heat (i.e., qE-type NPQ) during dark to light transition, as measured with chlorophyll fluorescence. The low qE phenotype of the npq4 mutant, which is unable to produce LHCSR3, was abolished under fluctuating light, showing that LHCSR1 alone enables very high levels of qE. Photosystem (PS) levels were also affected by light treatments; constant light led to lower PsbA levels and Fv/Fm values, while fluctuating light led to lower PsaA and maximum P700+ levels, indicating that constant and fluctuating light induced PSII and PSI photoinhibition, respectively. Under fluctuating light, npq4 suffered more PSI photoinhibition and significantly slower growth rates than parental wild type, whereas npq1 and npq2 mutants affected in xanthophyll carotenoid compositions had identical growth under fluctuating and constant light. Overall, LHCSR3 rather than total qE capacity or zeaxanthin is shown to be important in C. reinhardtii in tolerating fluctuating light, potentially via preventing PSI photoinhibition.
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Affiliation(s)
- Thomas Roach
- Department of Botany and Centre for Molecular Biosciences Innsbruck, University of Innsbruck, Sternwartestraße 15, 6020 Innsbruck, Austria
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37
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Emerging research in plant photosynthesis. Emerg Top Life Sci 2020; 4:137-150. [PMID: 32573736 DOI: 10.1042/etls20200035] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 06/03/2020] [Accepted: 06/05/2020] [Indexed: 12/27/2022]
Abstract
Photosynthesis involves capturing light energy and, most often, converting it to chemical energy stored as reduced carbon. It is the source of food, fuel, and fiber and there is a resurgent interest in basic research on photosynthesis. Plants make excellent use of visible light energy; leaves are ideally suited to optimize light use by having a large area per amount of material invested and also having leaf angles to optimize light utilization. It is thought that plants do not use green light but in fact they use green light better than blue light under some conditions. Leaves also have mechanisms to protect against excess light and how these work in a stochastic light environment is currently a very active area of current research. The speed at which photosynthesis can begin when leaves are first exposed to light and the speed of induction of protective mechanisms, as well as the speed at which protective mechanisms dissipate when light levels decline, have recently been explored. Research is also focused on reducing wasteful processes such as photorespiration, when oxygen instead of carbon dioxide is used. Some success has been reported in altering the path of carbon in photorespiration but on closer inspection there appears to be unforeseen effects contributing to the good news. The stoichiometry of interaction of light reactions with carbon metabolism is rigid and the time constants vary tremendously presenting large challenges to regulatory mechanisms. Regulatory mechanisms will be the topic of photosynthesis research for some time to come.
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Su L, Xie J, Wen W, Li J, Zhou P, An Y. Interaction of zinc and IAA alleviate aluminum-induced damage on photosystems via promoting proton motive force and reducing proton gradient in alfalfa. BMC PLANT BIOLOGY 2020; 20:433. [PMID: 32948141 PMCID: PMC7501636 DOI: 10.1186/s12870-020-02643-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/01/2020] [Accepted: 09/09/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND In acidic soils, aluminum (Al) competing with Zn results in Zn deficiency in plants. Zn is essential for auxin biosynthesis. Zn-mediated alleviation of Al toxicity has been rarely studied, the mechanism of Zn alleviation on Al-induced photoinhibition in photosystems remains unclear. The objective of this study was to investigate the effects of Zn and IAA on photosystems of Al-stressed alfalfa. Alfalfa seedlings with or without apical buds were exposed to 0 or100 μM AlCl3 combined with 0 or 50 μM ZnCl2, and then foliar spray with water or 6 mg L- 1 IAA. RESULTS Our results showed that Al stress significantly decreased plant growth rate, net photosynthetic rate (Pn), quantum yields and electron transfer rates of PSI and PSII. Exogenous application of Zn and IAA significantly alleviated the Al-induced negative effects on photosynthetic machinery, and an interaction of Zn and IAA played an important role in the alleviative effects. After removing apical buds of Al-stressed alfalfa seedlings, the values of pmf, gH+ and Y(II) under exogenous spraying IAA were significantly higher, and ΔpHpmf was significantly lower in Zn addition than Al treatment alone, but the changes did not occur under none spraying IAA. The interaction of Zn and IAA directly increased Y(I), Y(II), ETRI and ETRII, and decreased O2- content of Al-stressed seedlings. In addition, the transcriptome analysis showed that fourteen functionally noted genes classified into functional category of energy production and conversion were differentially expressed in leaves of alfalfa seedlings with and without apical buds. CONCLUSION Our results suggest that the interaction of zinc and IAA alleviate aluminum-induced damage on photosystems via increasing pmf and decreasing ΔpHpmf between lumen and stroma.
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Affiliation(s)
- Liantai Su
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
| | - Jianping Xie
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
| | - Wuwu Wen
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
| | - Jiaojiao Li
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
| | - Peng Zhou
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
| | - Yuan An
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China.
- Key Laboratory of Urban Agriculture, Ministry of Agriculture, Shanghai, 201101, China.
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Stirbet A, Lazár D, Guo Y, Govindjee G. Photosynthesis: basics, history and modelling. ANNALS OF BOTANY 2020; 126:511-537. [PMID: 31641747 PMCID: PMC7489092 DOI: 10.1093/aob/mcz171] [Citation(s) in RCA: 91] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 09/06/2019] [Accepted: 10/21/2019] [Indexed: 05/02/2023]
Abstract
BACKGROUND With limited agricultural land and increasing human population, it is essential to enhance overall photosynthesis and thus productivity. Oxygenic photosynthesis begins with light absorption, followed by excitation energy transfer to the reaction centres, primary photochemistry, electron and proton transport, NADPH and ATP synthesis, and then CO2 fixation (Calvin-Benson cycle, as well as Hatch-Slack cycle). Here we cover some of the discoveries related to this process, such as the existence of two light reactions and two photosystems connected by an electron transport 'chain' (the Z-scheme), chemiosmotic hypothesis for ATP synthesis, water oxidation clock for oxygen evolution, steps for carbon fixation, and finally the diverse mechanisms of regulatory processes, such as 'state transitions' and 'non-photochemical quenching' of the excited state of chlorophyll a. SCOPE In this review, we emphasize that mathematical modelling is a highly valuable tool in understanding and making predictions regarding photosynthesis. Different mathematical models have been used to examine current theories on diverse photosynthetic processes; these have been validated through simulation(s) of available experimental data, such as chlorophyll a fluorescence induction, measured with fluorometers using continuous (or modulated) exciting light, and absorbance changes at 820 nm (ΔA820) related to redox changes in P700, the reaction centre of photosystem I. CONCLUSIONS We highlight here the important role of modelling in deciphering and untangling complex photosynthesis processes taking place simultaneously, as well as in predicting possible ways to obtain higher biomass and productivity in plants, algae and cyanobacteria.
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Affiliation(s)
| | - Dušan Lazár
- Department of Biophysics, Center of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Šlechtitelů 27, 783 71 Olomouc, Czech Republic
| | - Ya Guo
- Key Laboratory of Advanced Process Control for Light Industry (Ministry of Education), Jiangnan University, Wuxi, China
- University of Missouri, Columbia, MO, USA
| | - Govindjee Govindjee
- Department of Biochemistry, Department of Plant Biology, and Center of Biophysics & Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
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Müller-Schüssele SJ, Wang R, Gütle DD, Romer J, Rodriguez-Franco M, Scholz M, Buchert F, Lüth VM, Kopriva S, Dörmann P, Schwarzländer M, Reski R, Hippler M, Meyer AJ. Chloroplasts require glutathione reductase to balance reactive oxygen species and maintain efficient photosynthesis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 103:1140-1154. [PMID: 32365245 DOI: 10.1111/tpj.14791] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 04/23/2020] [Accepted: 04/24/2020] [Indexed: 05/27/2023]
Abstract
Thiol-based redox-regulation is vital for coordinating chloroplast functions depending on illumination and has been throroughly investigated for thioredoxin-dependent processes. In parallel, glutathione reductase (GR) maintains a highly reduced glutathione pool, enabling glutathione-mediated redox buffering. Yet, how the redox cascades of the thioredoxin and glutathione redox machineries integrate metabolic regulation and detoxification of reactive oxygen species remains largely unresolved because null mutants of plastid/mitochondrial GR are embryo-lethal in Arabidopsis thaliana. To investigate whether maintaining a highly reducing stromal glutathione redox potential (EGSH ) via GR is necessary for functional photosynthesis and plant growth, we created knockout lines of the homologous enzyme in the model moss Physcomitrella patens. In these viable mutant lines, we found decreasing photosynthetic performance and plant growth with increasing light intensities, whereas ascorbate and zeaxanthin/antheraxanthin levels were elevated. By in vivo monitoring stromal EGSH dynamics, we show that stromal EGSH is highly reducing in wild-type and clearly responsive to light, whereas an absence of GR leads to a partial glutathione oxidation, which is not rescued by light. By metabolic labelling, we reveal changing protein abundances in the GR knockout plants, pinpointing the adjustment of chloroplast proteostasis and the induction of plastid protein repair and degradation machineries. Our results indicate that the plastid thioredoxin system is not a functional backup for the plastid glutathione redox systems, whereas GR plays a critical role in maintaining efficient photosynthesis.
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Affiliation(s)
- Stefanie J Müller-Schüssele
- Institute of Crop Science and Resource Conservation (INRES), University of Bonn, Friedrich-Ebert-Allee 144, Bonn, 53113, Germany
| | - Ren Wang
- Institute of Plant Biology and Biotechnology, University of Münster, Schlossplatz 8, Münster, 48143, Germany
| | - Desirée D Gütle
- Plant Biotechnology, Faculty of Biology, University of Freiburg, Schänzlestrasse1, Freiburg, 79104, Germany
| | - Jill Romer
- Institute of Molecular Physiology and Biotechnology of Plants, University of Bonn, Bonn, 53115, Germany
| | - Marta Rodriguez-Franco
- Cell Biology, Faculty of Biology, University of Freiburg, Schänzlestr. 1, Freiburg, 79104, Germany
| | - Martin Scholz
- Institute of Plant Biology and Biotechnology, University of Münster, Schlossplatz 8, Münster, 48143, Germany
| | - Felix Buchert
- Institute of Plant Biology and Biotechnology, University of Münster, Schlossplatz 8, Münster, 48143, Germany
| | - Volker M Lüth
- Plant Biotechnology, Faculty of Biology, University of Freiburg, Schänzlestrasse1, Freiburg, 79104, Germany
| | - Stanislav Kopriva
- Botanical Institute, Cluster of Excellence on Plant Sciences (CEPLAS), University of Cologne, Cologne, 50674, Germany
| | - Peter Dörmann
- Institute of Molecular Physiology and Biotechnology of Plants, University of Bonn, Bonn, 53115, Germany
| | - Markus Schwarzländer
- Institute of Plant Biology and Biotechnology, University of Münster, Schlossplatz 8, Münster, 48143, Germany
| | - Ralf Reski
- Plant Biotechnology, Faculty of Biology, University of Freiburg, Schänzlestrasse1, Freiburg, 79104, Germany
- Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Schänzlestrasse18, Freiburg, 79104, Germany
| | - Michael Hippler
- Institute of Plant Biology and Biotechnology, University of Münster, Schlossplatz 8, Münster, 48143, Germany
- Institute of Plant Science and Resources, Okayama University, Kurashiki, 710-0046, Japan
| | - Andreas J Meyer
- Institute of Crop Science and Resource Conservation (INRES), University of Bonn, Friedrich-Ebert-Allee 144, Bonn, 53113, Germany
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Efficient photosynthesis in dynamic light environments: a chloroplast's perspective. Biochem J 2020; 476:2725-2741. [PMID: 31654058 PMCID: PMC6792033 DOI: 10.1042/bcj20190134] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 08/23/2019] [Accepted: 09/03/2019] [Indexed: 12/21/2022]
Abstract
In nature, light availability for photosynthesis can undergo massive changes on a very short timescale. Photosynthesis in such dynamic light environments requires that plants can respond swiftly. Expanding our knowledge of the rapid responses that underlie dynamic photosynthesis is an important endeavor: it provides insights into nature's design of a highly dynamic energy conversion system and hereby can open up new strategies for improving photosynthesis in the field. The present review focuses on three processes that have previously been identified as promising engineering targets for enhancing crop yield by accelerating dynamic photosynthesis, all three of them involving or being linked to processes in the chloroplast, i.e. relaxation of non-photochemical quenching, Calvin–Benson–Bassham cycle enzyme activation/deactivation and dynamics of stomatal conductance. We dissect these three processes on the functional and molecular level to reveal gaps in our understanding and critically discuss current strategies to improve photosynthesis in the field.
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The plastid NAD(P)H dehydrogenase-like complex: structure, function and evolutionary dynamics. Biochem J 2020; 476:2743-2756. [PMID: 31654059 DOI: 10.1042/bcj20190365] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 08/27/2019] [Accepted: 09/02/2019] [Indexed: 11/17/2022]
Abstract
The thylakoid NAD(P)H dehydrogenase-like (NDH) complex is a large protein complex that reduces plastoquinone and pumps protons into the lumen generating protonmotive force. In plants, the complex consists of both nuclear and chloroplast-encoded subunits. Despite its perceived importance for stress tolerance and ATP generation, chloroplast-encoded NDH subunits have been lost numerous times during evolution in species occupying seemingly unrelated environmental niches. We have generated a phylogenetic tree that reveals independent losses in multiple phylogenetic lineages, and we use this tree as a reference to discuss possible evolutionary contexts that may have relaxed selective pressure for retention of ndh genes. While we are still yet unable to pinpoint a singular specific lifestyle that negates the need for NDH, we are able to rule out several long-standing explanations. In light of this, we discuss the biochemical changes that would be required for the chloroplast to dispense with NDH functionality with regards to known and proposed NDH-related reactions.
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Su L, Lv A, Wen W, Zhou P, An Y. Auxin Is Involved in Magnesium-Mediated Photoprotection in Photosystems of Alfalfa Seedlings Under Aluminum Stress. FRONTIERS IN PLANT SCIENCE 2020; 11:746. [PMID: 32582264 PMCID: PMC7286060 DOI: 10.3389/fpls.2020.00746] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 05/11/2020] [Indexed: 05/30/2023]
Abstract
The objective of this study was to investigate the effects of Mg and IAA on the photosystems of Al-stressed alfalfa (Medicago sativa L.). Alfalfa seedlings with or without apical buds were exposed to solutions fully mixed with 0 or 100 μM AlCl3 and 0 or 50 μM MgCl2 followed by foliar spray with water or IAA. Results from seedlings with apical buds showed that application of Mg and IAA either alone or combine greatly alleviated the Al-induced damage on photosystems. The values of photosynthetic rate (Pn), effective quantum yields [Y(I) and Y(II)] and electron transfer rates (ETRI and ETRII), proton motive force (pmf), cyclic electron flow (CEF), proton efflux rate (gH +), and activities of ATP synthase and PM H+-ATPase significantly increased, and proton gradient (ΔpH pmf ) between lumen and stroma decreased under Al stress. After removing apical buds of seedlings, the Y(I), Y(II), ETRI, ETRII, pmf, and gH + under exogenous spraying IAA significantly increased, and ΔpH pmf significantly decreased in Mg addition than Al treatment alone, but they were no significant difference under none spraying IAA. The interaction of Mg and IAA directly increased quantum yields and electron transfer rates, and decreased O2 - accumulation in Al-stressed seedlings with or without apical buds. These results suggest that IAA involves in Mg alleviation of Al-induced photosystem damage via increasing pmf and PM H+-ATPase activity, and decreasing ΔpH pmf .
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Affiliation(s)
- Liantai Su
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Aimin Lv
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Wuwu Wen
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Peng Zhou
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Yuan An
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
- Key Laboratory of Urban Agriculture, Ministry of Agriculture, Shanghai, China
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Wege S. Plants Increase Photosynthesis Efficiency by Lowering the Proton Gradient across the Thylakoid Membrane. PLANT PHYSIOLOGY 2020; 182:1812-1813. [PMID: 32253334 PMCID: PMC7140960 DOI: 10.1104/pp.20.00273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Affiliation(s)
- Stefanie Wege
- Australian Research Counci Centre of Excellence in Plant Energy Biology, Plant Research Centre, School of Agriculture, Food, and Wine, Waite Research Institute, University of Adelaide, Waite Campus, Glen Osmond, South Australia 5064, Australia
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45
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Correa Galvis V, Strand DD, Messer M, Thiele W, Bethmann S, Hübner D, Uflewski M, Kaiser E, Siemiatkowska B, Morris BA, Tóth SZ, Watanabe M, Brückner F, Höfgen R, Jahns P, Schöttler MA, Armbruster U. H + Transport by K + EXCHANGE ANTIPORTER3 Promotes Photosynthesis and Growth in Chloroplast ATP Synthase Mutants. PLANT PHYSIOLOGY 2020; 182:2126-2142. [PMID: 32041909 PMCID: PMC7140953 DOI: 10.1104/pp.19.01561] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 01/27/2020] [Indexed: 05/21/2023]
Abstract
The composition of the thylakoid proton motive force (pmf) is regulated by thylakoid ion transport. Passive ion channels in the thylakoid membrane dissipate the membrane potential (Δψ) component to allow for a higher fraction of pmf stored as a proton concentration gradient (ΔpH). K+/H+ antiport across the thylakoid membrane via K+ EXCHANGE ANTIPORTER3 (KEA3) instead reduces the ΔpH fraction of the pmf. Thereby, KEA3 decreases nonphotochemical quenching (NPQ), thus allowing for higher light use efficiency, which is particularly important during transitions from high to low light. Here, we show that in the background of the Arabidopsis (Arabidopsis thaliana) chloroplast (cp)ATP synthase assembly mutant cgl160, with decreased cpATP synthase activity and increased pmf amplitude, KEA3 plays an important role for photosynthesis and plant growth under steady-state conditions. By comparing cgl160 single with cgl160 kea3 double mutants, we demonstrate that in the cgl160 background loss of KEA3 causes a strong growth penalty. This is due to a reduced photosynthetic capacity of cgl160 kea3 mutants, as these plants have a lower lumenal pH than cgl160 mutants, and thus show substantially increased pH-dependent NPQ and decreased electron transport through the cytochrome b 6 f complex. Overexpression of KEA3 in the cgl160 background reduces pH-dependent NPQ and increases photosystem II efficiency. Taken together, our data provide evidence that under conditions where cpATP synthase activity is low, a KEA3-dependent reduction of ΔpH benefits photosynthesis and growth.
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Affiliation(s)
- Viviana Correa Galvis
- Max Planck Institute of Molecular Plant Physiology, Wissenschaftspark Golm, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Deserah D Strand
- Max Planck Institute of Molecular Plant Physiology, Wissenschaftspark Golm, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Michaela Messer
- Max Planck Institute of Molecular Plant Physiology, Wissenschaftspark Golm, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Wolfram Thiele
- Max Planck Institute of Molecular Plant Physiology, Wissenschaftspark Golm, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Stephanie Bethmann
- Institute of Plant Biochemistry, Heinrich-Heine-University Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany
| | - Dennis Hübner
- Max Planck Institute of Molecular Plant Physiology, Wissenschaftspark Golm, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Michal Uflewski
- Max Planck Institute of Molecular Plant Physiology, Wissenschaftspark Golm, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Elias Kaiser
- Max Planck Institute of Molecular Plant Physiology, Wissenschaftspark Golm, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Beata Siemiatkowska
- Max Planck Institute of Molecular Plant Physiology, Wissenschaftspark Golm, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Bethan A Morris
- Max Planck Institute of Molecular Plant Physiology, Wissenschaftspark Golm, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Szilvia Z Tóth
- Institute of Plant Biology, Biological Research Centre, Szeged, Temesvári krt 62, H-6726 Szeged, Hungary
| | - Mutsumi Watanabe
- Max Planck Institute of Molecular Plant Physiology, Wissenschaftspark Golm, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Franziska Brückner
- Max Planck Institute of Molecular Plant Physiology, Wissenschaftspark Golm, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Rainer Höfgen
- Max Planck Institute of Molecular Plant Physiology, Wissenschaftspark Golm, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Peter Jahns
- Institute of Plant Biochemistry, Heinrich-Heine-University Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany
| | - Mark Aurel Schöttler
- Max Planck Institute of Molecular Plant Physiology, Wissenschaftspark Golm, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Ute Armbruster
- Max Planck Institute of Molecular Plant Physiology, Wissenschaftspark Golm, Am Mühlenberg 1, 14476 Potsdam, Germany
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Yamada S, Ozaki H, Noguchi K. The Mitochondrial Respiratory Chain Maintains the Photosynthetic Electron Flow in Arabidopsis thaliana Leaves under High-Light Stress. PLANT & CELL PHYSIOLOGY 2020; 61:283-295. [PMID: 31603217 DOI: 10.1093/pcp/pcz193] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 10/07/2019] [Indexed: 05/02/2023]
Abstract
The plant respiratory chain includes the ATP-coupling cytochrome pathway (CP) and ATP-uncoupling alternative oxidase (AOX). Under high-light (HL) conditions, plants experience photoinhibition, leading to a damaged photosystem II (PSII). The respiratory chain is considered to affect PSII maintenance and photosynthetic electron transport under HL conditions. However, the underlying details remain unclear. In this study, we investigated the respiratory chain functions related to PSII maintenance and photosynthetic electron transport in plants exposed to HL stress. We measured the HL-induced decrease in the maximum quantum yield of PSII in the leaves of wild-type and AOX1a-knockout (aox1a) Arabidopsis thaliana plants in which CP was partially inhibited by a complex-III inhibitor. We also calculated PSII photodamage and repair rate constants. Both rate constants changed when CP was partially inhibited in aox1a plants, suggesting that the respiratory chain is related to both processes. Before HL stress, photosynthetic linear electron flow (LEF) decreased when CP was partially inhibited. After HL stress, aox1a in the presence of the CP inhibitor showed significantly decreased rates of LEF. The electron flow downstream from PSII and on the donor side of photosystem I may have been suppressed. The function of respiratory chain is required to maintain the optimal LEF as well as PSII maintenance especially under the HL stress.
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Affiliation(s)
- Shoya Yamada
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo, 192-0392 Japan
| | - Hiroshi Ozaki
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo, 192-0392 Japan
| | - Ko Noguchi
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo, 192-0392 Japan
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Davis GA, Kramer DM. Optimization of ATP Synthase c-Rings for Oxygenic Photosynthesis. FRONTIERS IN PLANT SCIENCE 2020; 10:1778. [PMID: 32082344 PMCID: PMC7003800 DOI: 10.3389/fpls.2019.01778] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 12/20/2019] [Indexed: 05/10/2023]
Abstract
The conversion of sunlight into useable cellular energy occurs via the proton-coupled electron transfer reactions of photosynthesis. Light is absorbed by photosynthetic pigments and transferred to photochemical reaction centers to initiate electron and proton transfer reactions to store energy in a redox gradient and an electrochemical proton gradient (proton motive force, pmf), composed of a concentration gradient (ΔpH) and an electric field (Δψ), which drives the synthesis of ATP through the thylakoid FoF1-ATP synthase. Although ATP synthase structure and function are conserved across biological kingdoms, the number of membrane-embedded ion-binding c subunits varies between organisms, ranging from 8 to 17, theoretically altering the H+/ATP ratio for different ATP synthase complexes, with profound implications for the bioenergetic processes of cellular metabolism. Of the known c-ring stoichiometries, photosynthetic c-rings are among the largest identified stoichiometries, and it has been proposed that decreasing the c-stoichiometry could increase the energy conversion efficiency of photosynthesis. Indeed, there is strong evidence that the high H+/ATP of the chloroplast ATP synthase results in a low ATP/nicotinamide adenine dinucleotide phosphate (NADPH) ratio produced by photosynthetic linear electron flow, requiring secondary processes such as cyclic electron flow to support downstream metabolism. We hypothesize that the larger c subunit stoichiometry observed in photosynthetic ATP synthases was selected for because it allows the thylakoid to maintain pmf in a range where ATP synthesis is supported, but avoids excess Δψ and ΔpH, both of which can lead to production of reactive oxygen species and subsequent photodamage. Numerical kinetic simulations of the energetics of chloroplast photosynthetic reactions with altered c-ring size predicts the energy storage of pmf and its effects on the photochemical reaction centers strongly support this hypothesis, suggesting that, despite the low efficiency and suboptimal ATP/NADPH ratio, a high H+/ATP is favored to avoid photodamage. This has important implications for the evolution and regulation of photosynthesis as well as for synthetic biology efforts to alter photosynthetic efficiency by engineering the ATP synthase.
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Affiliation(s)
- Geoffry A. Davis
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, United States
| | - David M. Kramer
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, United States
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, United States
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Khorobrykh S, Havurinne V, Mattila H, Tyystjärvi E. Oxygen and ROS in Photosynthesis. PLANTS (BASEL, SWITZERLAND) 2020; 9:E91. [PMID: 31936893 PMCID: PMC7020446 DOI: 10.3390/plants9010091] [Citation(s) in RCA: 120] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 12/29/2019] [Accepted: 01/02/2020] [Indexed: 12/14/2022]
Abstract
Oxygen is a natural acceptor of electrons in the respiratory pathway of aerobic organisms and in many other biochemical reactions. Aerobic metabolism is always associated with the formation of reactive oxygen species (ROS). ROS may damage biomolecules but are also involved in regulatory functions of photosynthetic organisms. This review presents the main properties of ROS, the formation of ROS in the photosynthetic electron transport chain and in the stroma of chloroplasts, and ROS scavenging systems of thylakoid membrane and stroma. Effects of ROS on the photosynthetic apparatus and their roles in redox signaling are discussed.
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Affiliation(s)
| | | | | | - Esa Tyystjärvi
- Department of Biochemistry/Molecular Plant Biology, University of Turku, FI-20014 Turku, Finland or (S.K.); (V.H.); (H.M.)
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Dissecting the Regulatory Network of Leaf Premature Senescence in Maize ( Zea mays L.) Using Transcriptome Analysis of ZmELS5 Mutant. Genes (Basel) 2019; 10:genes10110944. [PMID: 31752425 PMCID: PMC6895817 DOI: 10.3390/genes10110944] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2019] [Revised: 11/03/2019] [Accepted: 11/14/2019] [Indexed: 12/16/2022] Open
Abstract
Leaf premature senescence largely determines maize (Zea mays L.) grain yield and quality. A natural recessive premature-senescence mutant was selected from the breeding population, and near-isogenic lines were constructed using Jing24 as the recurrent parent. In the near-isogenic lines, the dominant homozygous material was wild-type (WT), and the recessive material of early leaf senescence was the premature-senescence-type ZmELS5. To identify major genes and regulatory mechanisms involved in leaf senescence, a transcriptome analysis of the ZmELS5 and WT near-isogenic lines (NILs) was performed. A total of 8796 differentially expressed transcripts were identified between ZmELS5 and WT, including 3811 up-regulated and 4985 down-regulated transcripts. By combining gene ontology, Kyoto Encyclopedia of Genes and Genomes, gene set, and transcription factor enrichment analyses, key differentially expressed genes were screened. The senescence regulatory network was predicted based on these key differentially expressed genes, which indicated that the senescence process is mainly regulated by bHLH, WRKY, and AP2/EREBP family transcription factors, leading to the accumulations of jasmonic acid and ethylene. This causes stress responses and reductions in the chlorophyll a/b-binding protein activity level. Then, decreased ATP synthase activity leads to increased photosystem II photodamage, ultimately leading to leaf senescence.
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Wang C, Shikanai T. Modification of Activity of the Thylakoid H +/K + Antiporter KEA3 Disturbs ∆pH-Dependent Regulation of Photosynthesis. PLANT PHYSIOLOGY 2019; 181:762-773. [PMID: 31427465 PMCID: PMC6776848 DOI: 10.1104/pp.19.00766] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 08/07/2019] [Indexed: 05/19/2023]
Abstract
The thylakoid K+ efflux antiporter 3 (KEA3) is required for regulating components of the proton motive force (pmf), proton concentration gradient (ΔpH), and membrane potential (Δψ). The Arabidopsis (Arabidopsis thaliana) disturbed proton gradient regulation mutant (dpgr) is a dominant allele of KEA3, conferring disturbed transport activity. Here, we show that overexpressing the DPGR-type KEA3 (DPGRox) retarded plant growth, whereas overexpressing the wild-type KEA3 (KEA3ox) did not. In KEA3ox lines, the contribution of Δψ to pmf was enhanced, but in DPGRox lines, the size of pmf was reduced. In DPGRox plants, proton conductivity of the thylakoid membrane (g H +) was elevated under high light, implying disturbed stoichiometry of H+/K+ antiport through DPGR-type KEA3 rather than simply enhanced activity. The ΔpH-dependent regulation consisting of thermal dissipation of excessively absorbed light energy and downregulation of cytochrome b 6 f complex activity was severely and mildly affected in DPGRox and KEA3ox plants, respectively. Consequently, photosystem I was sensitive to fluctuating light in both transgenic plants. Both photosystems were sensitive to constant high light and were slightly photodamaged even at standard growth light intensity in DPGRox plants. KEA3 regulates the components of pmf and optimizes the operation of ∆pH-dependent regulation of electron transport.
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Affiliation(s)
- Caijuan Wang
- Department of Botany, Graduate School of Science, Kyoto University, Kyoto, 606-8502 Japan
| | - Toshiharu Shikanai
- Department of Botany, Graduate School of Science, Kyoto University, Kyoto, 606-8502 Japan
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