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Hubáček M, Wey LT, Kourist R, Malihan-Yap L, Nikkanen L, Allahverdiyeva Y. Strong heterologous electron sink outcompetes alternative electron transport pathways in photosynthesis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024. [PMID: 39008444 DOI: 10.1111/tpj.16935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 05/27/2024] [Accepted: 07/03/2024] [Indexed: 07/17/2024]
Abstract
Improvement of photosynthesis requires a thorough understanding of electron partitioning under both natural and strong electron sink conditions. We applied a wide array of state-of-the-art biophysical and biochemical techniques to thoroughly investigate the fate of photosynthetic electrons in the engineered cyanobacterium Synechocystis sp. PCC 6803, a blueprint for photosynthetic biotechnology, expressing the heterologous gene for ene-reductase, YqjM. This recombinant enzyme catalyses the reduction of an exogenously added substrate into the desired product by utilising photosynthetically produced NAD(P)H, enabling whole-cell biotransformation. Through coupling the biotransformation reaction with biophysical measurements, we demonstrated that the strong artificial electron sink, outcompetes the natural electron valves, the flavodiiron protein-driven Mehler-like reaction and cyclic electron transport. These results show that ferredoxin-NAD(P)H-oxidoreductase is the preferred route for delivering photosynthetic electrons from reduced ferredoxin and the cellular NADPH/NADP+ ratio as a key factor in orchestrating photosynthetic electron flux. These insights are crucial for understanding molecular mechanisms of photosynthetic electron transport and harnessing photosynthesis for sustainable bioproduction by engineering the cellular source/sink balance. Furthermore, we conclude that identifying the bioenergetic bottleneck of a heterologous electron sink is a crucial prerequisite for targeted engineering of photosynthetic biotransformation platforms.
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Affiliation(s)
- Michal Hubáček
- Molecular Plant Biology, Department of Life Technologies, University of Turku, Turku, 20014, Finland
| | - Laura T Wey
- Molecular Plant Biology, Department of Life Technologies, University of Turku, Turku, 20014, Finland
| | - Robert Kourist
- Institute of Molecular Biotechnology, NAWI Graz, BioTechMed, Graz University of Technology, Graz, 8010, Austria
| | - Lenny Malihan-Yap
- Institute of Molecular Biotechnology, NAWI Graz, BioTechMed, Graz University of Technology, Graz, 8010, Austria
| | - Lauri Nikkanen
- Molecular Plant Biology, Department of Life Technologies, University of Turku, Turku, 20014, Finland
| | - Yagut Allahverdiyeva
- Molecular Plant Biology, Department of Life Technologies, University of Turku, Turku, 20014, Finland
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2
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Wang T, Sun Q, Zheng Y, Xu Y, Liu B, Li Q. Effects of Red and Blue Light on the Growth, Photosynthesis, and Subsequent Growth under Fluctuating Light of Cucumber Seedlings. PLANTS (BASEL, SWITZERLAND) 2024; 13:1668. [PMID: 38931100 PMCID: PMC11207261 DOI: 10.3390/plants13121668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2024] [Revised: 05/24/2024] [Accepted: 06/14/2024] [Indexed: 06/28/2024]
Abstract
The effects of red and blue light on growth and steady-state photosynthesis have been widely studied, but there are few studies focusing on dynamic photosynthesis and the effects of LED pre-treatment on cucumber seedlings' growth, so in this study, cucumber (Cucumis sativus L. cv. Jinyou 365) was chosen as the test material. White light (W), monochromatic red light (R), monochromatic blue light (B), and mixed red and blue lights with different red-to-blue ratios (9:1, 7:3, 5:5, 3:7, and 1:9) were set to explore the effects of red and blue light on cucumber seedlings' growth, steady-state photosynthesis, dynamic photosynthesis, and subsequent growth under fluctuating light. The results showed that compared with R and B, mixed red and blue light was more suitable for cucumber seedlings' growth, and the increased blue light ratios would decrease the biomass of cucumber seedlings under mixed red and blue light; cucumber seedlings under 90% red and 10% blue mixed light (9R1B) grew better than other treatments. For steady-state photosynthesis, blue light decreased the actual net photosynthetic rate but increased the maximum photosynthetic capacity by promoting stomatal development and opening; 9R1B exhibited higher actual net photosynthetic rate, but the maximum photosynthetic capacity was low. For dynamic photosynthesis, the induction rate of photosynthetic rate and stomatal conductance were also accelerated by blue light. For subsequent growth under fluctuating light, higher maximum photosynthetic capacity and photoinduction rate could not promote the growth of cucumber seedlings under subsequent fluctuating light, while seedlings pre-treated with 9R1B and B grew better under subsequent fluctuating light due to the high plant height and leaf area. Overall, cucumber seedlings treated with 9R1B exhibited the highest biomass and it grew better under subsequent fluctuating light due to the higher actual net photosynthetic rate, plant height, and leaf area.
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Affiliation(s)
- Tengqi Wang
- College of Horticulture Science and Engineering, Shandong Agriculture University, Tai’an 271018, China; (T.W.); (Q.S.)
| | - Qiying Sun
- College of Horticulture Science and Engineering, Shandong Agriculture University, Tai’an 271018, China; (T.W.); (Q.S.)
| | - Yinjian Zheng
- Institute of Urban Agriculture, Chinese Academy of Agricultural Sciences, Chengdu 610299, China; (Y.Z.); (Y.X.)
| | - Yaliang Xu
- Institute of Urban Agriculture, Chinese Academy of Agricultural Sciences, Chengdu 610299, China; (Y.Z.); (Y.X.)
| | - Binbin Liu
- College of Food and Biological Engineering, Chengdu University, Chengdu 610106, China
| | - Qingming Li
- Institute of Urban Agriculture, Chinese Academy of Agricultural Sciences, Chengdu 610299, China; (Y.Z.); (Y.X.)
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3
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Niu Y, Matsubara S, Nedbal L, Lazár D. Dynamics and interplay of photosynthetic regulatory processes depend on the amplitudes of oscillating light. PLANT, CELL & ENVIRONMENT 2024; 47:2240-2257. [PMID: 38482712 DOI: 10.1111/pce.14879] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 02/28/2024] [Indexed: 04/30/2024]
Abstract
Plants have evolved multiple regulatory mechanisms to cope with natural light fluctuations. The interplay between these mechanisms leads presumably to the resilience of plants in diverse light patterns. We investigated the energy-dependent nonphotochemical quenching (qE) and cyclic electron transports (CET) in light that oscillated with a 60-s period with three different amplitudes. The photosystem I (PSI) and photosystem II (PSII) function-related quantum yields and redox changes of plastocyanin and ferredoxin were measured in Arabidopsis thaliana wild types and mutants with partial defects in qE or CET. The decrease in quantum yield of qE due to the lack of either PsbS- or violaxanthin de-epoxidase was compensated by an increase in the quantum yield of the constitutive nonphotochemical quenching. The mutant lacking NAD(P)H dehydrogenase (NDH)-like-dependent CET had a transient significant PSI acceptor side limitation during the light rising phase under high amplitude of light oscillations. The mutant lacking PGR5/PGRL1-CET restricted electron flows and failed to induce effective photosynthesis control, regardless of oscillation amplitudes. This suggests that PGR5/PGRL1-CET is important for the regulation of PSI function in various amplitudes of light oscillation, while NDH-like-CET acts' as a safety valve under fluctuating light with high amplitude. The results also bespeak interplays among multiple photosynthetic regulatory mechanisms.
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Affiliation(s)
- Yuxi Niu
- Institute of Bio- and Geosciences/Plant Sciences, Forschungszentrum Jülich, Wilhelm-Johnen-Straße, Jülich, Germany
| | - Shizue Matsubara
- Institute of Bio- and Geosciences/Plant Sciences, Forschungszentrum Jülich, Wilhelm-Johnen-Straße, Jülich, Germany
| | - Ladislav Nedbal
- Institute of Bio- and Geosciences/Plant Sciences, Forschungszentrum Jülich, Wilhelm-Johnen-Straße, Jülich, Germany
- Department of Biophysics, Faculty of Science, Palacký University, Olomouc, Czech Republic
| | - Dušan Lazár
- Department of Biophysics, Faculty of Science, Palacký University, Olomouc, Czech Republic
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Kurima K, Jimbo H, Fujihara T, Saito M, Ishikawa T, Wada H. High Myristic Acid in Glycerolipids Enhances the Repair of Photodamaged Photosystem II under Strong Light. PLANT & CELL PHYSIOLOGY 2024; 65:790-797. [PMID: 38441322 PMCID: PMC11138363 DOI: 10.1093/pcp/pcae021] [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: 12/18/2023] [Revised: 02/21/2024] [Accepted: 03/01/2024] [Indexed: 05/31/2024]
Abstract
Cyanobacteria inhabit areas with a broad range of light, temperature and nutrient conditions. The robustness of cyanobacterial cells, which can survive under different conditions, may depend on the resilience of photosynthetic activity. Cyanothece sp. PCC 8801 (Cyanothece), a freshwater cyanobacterium isolated from a Taiwanese rice field, had a higher repair activity of photodamaged photosystem II (PSII) under intense light than Synechocystis sp. PCC 6803 (Synechocystis), another freshwater cyanobacterium. Cyanothece contains myristic acid (14:0) as the major fatty acid at the sn-2 position of the glycerolipids. To investigate the role of 14:0 in the repair of photodamaged PSII, we used a Synechocystis transformant expressing a T-1274 encoding a lysophosphatidic acid acyltransferase (LPAAT) from Cyanothece. The wild-type and transformant cells contained 0.2 and 20.1 mol% of 14:0 in glycerolipids, respectively. The higher content of 14:0 in the transformants increased the fluidity of the thylakoid membrane. In the transformants, PSII repair was accelerated due to an enhancement in the de novo synthesis of D1 protein, and the production of singlet oxygen (1O2), which inhibited protein synthesis, was suppressed. The high content of 14:0 increased transfer of light energy received by phycobilisomes to PSI and CP47 in PSII and the content of carotenoids. These results indicated that an increase in 14:0 reduced 1O2 formation and enhanced PSII repair. The higher content of 14:0 in the glycerolipids may be required as a survival strategy for Cyanothece inhabiting a rice field under direct sunlight.
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Affiliation(s)
- Kazuki Kurima
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
| | - Haruhiko Jimbo
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
| | - Takashi Fujihara
- Comprehensive Analysis Center for Science, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan
| | - Masakazu Saito
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
- Department of Bioscience, Nagahama Institute of Bio-Science and Technology, 1266, Tamura, Nagahama, Shiga 526-0829, Japan
| | - Toshiki Ishikawa
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan
| | - Hajime Wada
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
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Shang Y, He J, Qiu J, Hu S, Wang X, Zhang T, Wang W, Yuan X, Xu J, Li F. The tolerance of two marine diatoms to diurnal pH fluctuation under dynamic light condition and ocean acidification scenario. MARINE ENVIRONMENTAL RESEARCH 2024; 196:106425. [PMID: 38442592 DOI: 10.1016/j.marenvres.2024.106425] [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: 10/23/2023] [Revised: 01/29/2024] [Accepted: 02/25/2024] [Indexed: 03/07/2024]
Abstract
Coastal waters undergo dynamic changes in seawater carbonate chemistry due to natural and anthropogenic factors. Despite this, our current understanding of how coastal phytoplankton respond to fluctuating pH is limited. In the present study, we investigated the physiological responses of two coastal diatoms Thalassiosira pseudonana and Thalassiosira weissflogii to seawater acidification and diurnally fluctuating pH under natural solar irradiance. Seawater acidification did not significantly impact the growth, maximum and effective quantum yield of PSII, and photosynthetic rates of the two species. However, it did increase the maximum relative electron transport rate of T. weissflogii by 11%. Overall, fluctuating pH had neutral or positive effects on both species. It enhanced the light-saturated photosynthetic rate of T. weissflogii by 20% compared to cells grown under seawater acidification condition. Results from the short-term pH exposure experiment revealed that the photosynthetic rates of both species remained unaffected by acute pH changes, indicating their tolerance to varying pH. Nevertheless, it is crucial to consider dynamic pH when predicting changes in primary production in coastal waters, given the interplay of various environmental drivers.
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Affiliation(s)
- Yu Shang
- Jiangsu Key Laboratory of Marine Bioresources and Environment/Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang, China
| | - Jie He
- Jiangsu Key Laboratory of Marine Bioresources and Environment/Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang, China
| | - Jingmin Qiu
- Jiangsu Key Laboratory of Marine Bioresources and Environment/Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang, China
| | - Siyu Hu
- Jiangsu Key Laboratory of Marine Bioresources and Environment/Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang, China
| | - Xin Wang
- Jiangsu Key Laboratory of Marine Bioresources and Environment/Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang, China
| | - Tianzhi Zhang
- Jiangsu Key Laboratory of Marine Bioresources and Environment/Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang, China
| | - Weili Wang
- Jiangsu Key Laboratory of Marine Bioresources and Environment/Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang, China
| | - Xiaoyue Yuan
- Jiangsu Key Laboratory of Marine Bioresources and Environment/Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang, China
| | - Juntian Xu
- Jiangsu Key Laboratory of Marine Bioresources and Environment/Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang, China
| | - Futian Li
- Jiangsu Key Laboratory of Marine Bioresources and Environment/Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang, China; Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang, China; Marine Resources Development Institute of Jiangsu, Jiangsu Ocean University, Lianyungang, China.
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6
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Maekawa S, Ohnishi M, Wada S, Ifuku K, Miyake C. Enhanced Reduction of Ferredoxin in PGR5-Deficient Mutant of Arabidopsis thaliana Stimulated Ferredoxin-Dependent Cyclic Electron Flow around Photosystem I. Int J Mol Sci 2024; 25:2677. [PMID: 38473924 DOI: 10.3390/ijms25052677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2024] [Revised: 02/12/2024] [Accepted: 02/25/2024] [Indexed: 03/14/2024] Open
Abstract
The molecular entity responsible for catalyzing ferredoxin (Fd)-dependent cyclic electron flow around photosystem I (Fd-CEF) remains unidentified. To reveal the in vivo molecular mechanism of Fd-CEF, evaluating ferredoxin reduction-oxidation kinetics proves to be a reliable indicator of Fd-CEF activity. Recent research has demonstrated that the expression of Fd-CEF activity is contingent upon the oxidation of plastoquinone. Moreover, chloroplast NAD(P)H dehydrogenase does not catalyze Fd-CEF in Arabidopsis thaliana. In this study, we analyzed the impact of reduced Fd on Fd-CEF activity by comparing wild-type and pgr5-deficient mutants (pgr5hope1). PGR5 has been proposed as the mediator of Fd-CEF, and pgr5hope1 exhibited a comparable CO2 assimilation rate and the same reduction-oxidation level of PQ as the wild type. However, P700 oxidation was suppressed with highly reduced Fd in pgr5hope1, unlike in the wild type. As anticipated, the Fd-CEF activity was enhanced in pgr5hope1 compared to the wild type, and its activity further increased with the oxidation of PQ due to the elevated CO2 assimilation rate. This in vivo research clearly demonstrates that the expression of Fd-CEF activity requires not only reduced Fd but also oxidized PQ. Importantly, PGR5 was found to not catalyze Fd-CEF, challenging previous assumptions about its role in this process.
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Affiliation(s)
- Shu Maekawa
- Graduate School for Agricultural Science, Kobe University, 1-1 Rokkodai, Nada-Ku, Kobe 657-8501, Japan
| | - Miho Ohnishi
- Graduate School for Agricultural Science, Kobe University, 1-1 Rokkodai, Nada-Ku, Kobe 657-8501, Japan
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), 7 Gobancho, Kyoto 606-8502, Japan
| | - Shinya Wada
- Graduate School for Agricultural Science, Kobe University, 1-1 Rokkodai, Nada-Ku, Kobe 657-8501, Japan
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), 7 Gobancho, Kyoto 606-8502, Japan
| | - Kentaro Ifuku
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), 7 Gobancho, Kyoto 606-8502, Japan
- Graduate School for Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Chikahiro Miyake
- Graduate School for Agricultural Science, Kobe University, 1-1 Rokkodai, Nada-Ku, Kobe 657-8501, Japan
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), 7 Gobancho, Kyoto 606-8502, Japan
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Napaumpaiporn P, Ogawa T, Sonoike K, Nishiyama Y. Improved capacity for the repair of photosystem II via reinforcement of the translational and antioxidation systems in Synechocystis sp. PCC 6803. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 117:1165-1178. [PMID: 37983611 DOI: 10.1111/tpj.16551] [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: 07/26/2023] [Revised: 10/31/2023] [Accepted: 11/06/2023] [Indexed: 11/22/2023]
Abstract
In the cyanobacterium Synechocystis sp. PCC 6803, translation factor EF-Tu is inactivated by reactive oxygen species (ROS) via oxidation of Cys82 and the oxidation of EF-Tu enhances the inhibition of the repair of photosystem II (PSII) by suppressing protein synthesis. In our present study, we generated transformants of Synechocystis that overexpressed a mutated form of EF-Tu, designated EF-Tu (C82S), in which Cys82 had been replaced by a Ser residue, and ROS-scavenging enzymes individually or together. Expression of EF-Tu (C82S) alone in Synechocystis enhanced the repair of PSII under strong light, with the resultant mitigation of PSII photoinhibition, but it stimulated the production of ROS. However, overexpression of superoxide dismutase and catalase, together with the expression of EF-Tu (C82S), lowered intracellular levels of ROS and enhanced the repair of PSII more significantly under strong light, via facilitation of the synthesis de novo of the D1 protein. By contrast, the activity of photosystem I was hardly affected in wild-type cells and in all the lines of transformed cells under the same strong-light conditions. Furthermore, transformed cells that overexpressed EF-Tu (C82S), superoxide dismutase, and catalase were able to survive longer under stronger light than wild-type cells. Thus, the reinforced capacity for both protein synthesis and ROS scavenging allowed both photosynthesis and cell proliferation to tolerate strong light.
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Affiliation(s)
- Pornpan Napaumpaiporn
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama, 338-8570, Japan
| | - Takako Ogawa
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama, 338-8570, Japan
| | - Kintake Sonoike
- Faculty of Education and Integrated Arts and Sciences, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480, Japan
| | - Yoshitaka Nishiyama
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama, 338-8570, Japan
- Green Bioscience Research Area, Strategic Research Center, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama, 338-8570, Japan
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8
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Chaturvedi AK, Dym O, Levin Y, Fluhr R. PGR5-LIKE PHOTOSYNTHETIC PHENOTYPE1A redox states alleviate photoinhibition during changes in light intensity. PLANT PHYSIOLOGY 2024; 194:1059-1074. [PMID: 37787609 DOI: 10.1093/plphys/kiad518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 09/06/2023] [Accepted: 09/11/2023] [Indexed: 10/04/2023]
Abstract
Plants have evolved photosynthetic regulatory mechanisms to maintain homeostasis in response to light changes during diurnal transitions and those caused by passing clouds or by wind. One such adaptation directs photosynthetic electron flow to a cyclic pathway to alleviate excess energy surges. Here, we assign a function to regulatory cysteines of PGR5-like protein 1A (PGRL1A), a constituent of the PROTON GRADIENT REGULATION5 (PGR5)-dependent cyclic electron flow (CEF) pathway. During step increases from darkness to low light intensity in Arabidopsis (Arabidopsis thaliana), the intermolecular disulfide of the PGRL1A 59-kDa complex was reduced transiently within seconds to the 28-kDa form. In contrast, step increases from darkness to high light stimulated a stable, partially reduced redox state in PGRL1A. Mutations of 2 cysteines in PGRL1A, Cys82 and Cys183, resulted in a constitutively pseudo-reduced state. The mutant displayed higher proton motive force (PMF) and nonphotochemical quenching (NPQ) than the wild type (WT) and showed altered donor and acceptor dynamic flow around PSI. These changes were found to correspond with the redox state of PGRL1A. Continuous light regimes did not affect mutant growth compared to the WT. However, under fluctuating regimes of high light, the mutant showed better growth than the WT. In contrast, in fluctuating regimes of low light, the mutant displayed a growth penalty that can be attributed to constant stimulation of CEF under low light. Treatment with photosynthetic inhibitors indicated that PGRL1A redox state control depends on the penultimate Fd redox state. Our results showed that redox state changes in PGRL1A are crucial to optimize photosynthesis.
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Affiliation(s)
- Amit Kumar Chaturvedi
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Orly Dym
- Department of Life Science Core Facilities, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Yishai Levin
- The Nancy and Stephen Grand Israel National Center for Personalized Medicine, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Robert Fluhr
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
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Ji D, Luo M, Guo Y, Li Q, Kong L, Ge H, Wang Q, Song Q, Zeng X, Ma J, Wang Y, Meurer J, Chi W. Efficient scavenging of reactive carbonyl species in chloroplasts is required for light acclimation and fitness of plants. THE NEW PHYTOLOGIST 2023; 240:676-693. [PMID: 37545368 DOI: 10.1111/nph.19156] [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: 01/17/2023] [Accepted: 07/03/2023] [Indexed: 08/08/2023]
Abstract
Reactive carbonyl species (RCS) derived from lipid peroxides can act as critical damage or signaling mediators downstream of reactive oxygen species by modifying target proteins. However, their biological effects and underlying mechanisms remain largely unknown in plants. Here, we have uncovered the mechanism by which the RCS 4-hydroxy-(E)-2-nonenal (HNE) participates in photosystem II (PSII) repair cycle of chloroplasts, a crucial process for maintaining PSII activity under high and changing light conditions. High Light Sensitive 1 (HLT1) is a potential NADPH-dependent reductase in chloroplasts. Deficiency of HLT1 had no impact on the growth of Arabidopsis plants under normal light conditions but increased sensitivity to high light, which resulted from a defective PSII repair cycle. In hlt1 plants, the accumulation of HNE-modified D1 subunit of PSII was observed, which did not affect D1 degradation but hampered the dimerization of repaired PSII monomers and reassembly of PSII supercomplexes on grana stacks. HLT1 is conserved in all photosynthetic organisms and has functions in overall growth and plant fitness in both Arabidopsis and rice under naturally challenging field conditions. Our work provides the mechanistic basis underlying RCS scavenging in light acclimation and suggests a potential strategy to improve plant productivity by manipulating RCS signaling in chloroplasts.
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Affiliation(s)
- Daili Ji
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Manfei Luo
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yinjie Guo
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qiuxin Li
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Lingxi Kong
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Haitao Ge
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Qi Wang
- Institute of Crop Cultivation and Tillage, Heilongjiang Academy of Agricultural Sciences, Harbin, 150086, China
| | - Qiulai Song
- Institute of Crop Cultivation and Tillage, Heilongjiang Academy of Agricultural Sciences, Harbin, 150086, China
| | - Xiannan Zeng
- Institute of Crop Cultivation and Tillage, Heilongjiang Academy of Agricultural Sciences, Harbin, 150086, China
| | - Jinfang Ma
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Yingchun Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Jörg Meurer
- Plant Molecular Biology, Faculty of Biology, Ludwig-Maximilians-University, D-82152, Planegg-Martinsried, Munich, Germany
| | - Wei Chi
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
- The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
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10
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Gollan PJ, Grebe S, Roling L, Grimm B, Spetea C, Aro E. Photosynthetic and transcriptome responses to fluctuating light in Arabidopsis thylakoid ion transport triple mutant. PLANT DIRECT 2023; 7:e534. [PMID: 37886682 PMCID: PMC10598627 DOI: 10.1002/pld3.534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 08/29/2023] [Accepted: 09/14/2023] [Indexed: 10/28/2023]
Abstract
Fluctuating light intensity challenges fluent photosynthetic electron transport in plants, inducing photoprotection while diminishing carbon assimilation and growth, and also influencing photosynthetic signaling for regulation of gene expression. Here, we employed in vivo chlorophyll-a fluorescence and P700 difference absorption measurements to demonstrate the enhancement of photoprotective energy dissipation of both photosystems in wild-type Arabidopsis thaliana after 6 h exposure to fluctuating light as compared with constant light conditions. This acclimation response to fluctuating light was hampered in a triple mutant lacking the thylakoid ion transport proteins KEA3, VCCN1, and CLCe, leading to photoinhibition of photosystem I. Transcriptome analysis revealed upregulation of genes involved in biotic stress and defense responses in both genotypes after exposure to fluctuating as compared with constant light, yet these responses were demonstrated to be largely upregulated in triple mutant already under constant light conditions compared with wild type. The current study illustrates the rapid acclimation of plants to fluctuating light, including photosynthetic, transcriptomic, and metabolic adjustments, and highlights the connection among thylakoid ion transport, photosynthetic energy balance, and cell signaling.
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Affiliation(s)
- Peter J. Gollan
- Department of Life Technologies, Molecular Plant BiologyUniversity of TurkuTurkuFinland
| | - Steffen Grebe
- Department of Life Technologies, Molecular Plant BiologyUniversity of TurkuTurkuFinland
- Present address:
Optics of Photosynthesis Laboratory, Institute for Atmospheric and Earth System Research (INAR)/Forest Sciences, Viikki Plant Science Center (ViPS)University of HelsinkiHelsinkiFinland
| | - Lena Roling
- Institute of Biology/Plant PhysiologyHumboldt‐Universität zu BerlinBerlinGermany
| | - Bernhard Grimm
- Institute of Biology/Plant PhysiologyHumboldt‐Universität zu BerlinBerlinGermany
| | - Cornelia Spetea
- Department of Biological and Environmental SciencesUniversity of GothenburgGothenburgSweden
| | - Eva‐Mari Aro
- Department of Life Technologies, Molecular Plant BiologyUniversity of TurkuTurkuFinland
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11
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Zhan X, Qiu T, Zhang H, Hou K, Liang X, Chen C, Wang Z, Wu Q, Wang X, Li XL, Wang M, Feng S, Zeng H, Yu C, Wang H, Shen C. Mass spectrometry imaging and single-cell transcriptional profiling reveal the tissue-specific regulation of bioactive ingredient biosynthesis in Taxus leaves. PLANT COMMUNICATIONS 2023; 4:100630. [PMID: 37231648 PMCID: PMC10504593 DOI: 10.1016/j.xplc.2023.100630] [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: 12/29/2022] [Revised: 03/31/2023] [Accepted: 05/22/2023] [Indexed: 05/27/2023]
Abstract
Taxus leaves provide the raw industrial materials for taxol, a natural antineoplastic drug widely used in the treatment of various cancers. However, the precise distribution, biosynthesis, and transcriptional regulation of taxoids and other active components in Taxus leaves remain unknown. Matrix-assisted laser desorption/ionization-mass spectrometry imaging analysis was used to visualize various secondary metabolites in leaf sections of Taxus mairei, confirming the tissue-specific accumulation of different active metabolites. Single-cell sequencing was used to produce expression profiles of 8846 cells, with a median of 2352 genes per cell. Based on a series of cluster-specific markers, cells were grouped into 15 clusters, suggesting a high degree of cell heterogeneity in T. mairei leaves. Our data were used to create the first Taxus leaf metabolic single-cell atlas and to reveal spatial and temporal expression patterns of several secondary metabolic pathways. According to the cell-type annotation, most taxol biosynthesis genes are expressed mainly in leaf mesophyll cells; phenolic acid and flavonoid biosynthesis genes are highly expressed in leaf epidermal cells (including the stomatal complex and guard cells); and terpenoid and steroid biosynthesis genes are expressed specifically in leaf mesophyll cells. A number of novel and cell-specific transcription factors involved in secondary metabolite biosynthesis were identified, including MYB17, WRKY12, WRKY31, ERF13, GT_2, and bHLH46. Our research establishes the transcriptional landscape of major cell types in T. mairei leaves at a single-cell resolution and provides valuable resources for studying the basic principles of cell-type-specific regulation of secondary metabolism.
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Affiliation(s)
- Xiaori Zhan
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China; Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, Hangzhou Normal University, Hangzhou 311121, China
| | - Tian Qiu
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China; Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, Hangzhou Normal University, Hangzhou 311121, China
| | - Hongshan Zhang
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China; Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, Hangzhou Normal University, Hangzhou 311121, China; Kharkiv Institute, Hangzhou Normal University, Hangzhou 311121, China
| | - Kailin Hou
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China; Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, Hangzhou Normal University, Hangzhou 311121, China
| | - Xueshuang Liang
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China; Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, Hangzhou Normal University, Hangzhou 311121, China
| | - Cheng Chen
- College of Pharmacy, Hangzhou Normal University, Hangzhou 311121, China
| | - Zhijing Wang
- College of Pharmacy, Hangzhou Normal University, Hangzhou 311121, China
| | - Qicong Wu
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China; Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, Hangzhou Normal University, Hangzhou 311121, China
| | - Xiaojia Wang
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China
| | - Xiao-Lin Li
- State Key Laboratory Breeding Base of Dao-di Herbs, National Resource Center for Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing 100700, China
| | - Mingshuang Wang
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China; Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, Hangzhou Normal University, Hangzhou 311121, China
| | - Shangguo Feng
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China; Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, Hangzhou Normal University, Hangzhou 311121, China
| | - Houqing Zeng
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China; Kharkiv Institute, Hangzhou Normal University, Hangzhou 311121, China
| | - Chunna Yu
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China; Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, Hangzhou Normal University, Hangzhou 311121, China
| | - Huizhong Wang
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China; Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, Hangzhou Normal University, Hangzhou 311121, China.
| | - Chenjia Shen
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China; Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, Hangzhou Normal University, Hangzhou 311121, China; Kharkiv Institute, Hangzhou Normal University, Hangzhou 311121, China.
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12
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Saroussi S, Redekop P, Karns DAJ, Thomas DC, Wittkopp TM, Posewitz MC, Grossman AR. Restricting electron flow at cytochrome b6f when downstream electron acceptors are severely limited. PLANT PHYSIOLOGY 2023; 192:789-804. [PMID: 36960590 PMCID: PMC10231464 DOI: 10.1093/plphys/kiad185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 02/21/2023] [Accepted: 02/22/2023] [Indexed: 06/01/2023]
Abstract
Photosynthetic organisms frequently experience abiotic stress that restricts their growth and development. Under such circumstances, most absorbed solar energy cannot be used for CO2 fixation and can cause the photoproduction of reactive oxygen species (ROS) that can damage the photosynthetic reaction centers of PSI and PSII, resulting in a decline in primary productivity. This work describes a biological "switch" in the green alga Chlamydomonas reinhardtii that reversibly restricts photosynthetic electron transport (PET) at the cytochrome b6f (Cyt b6f) complex when the capacity for accepting electrons downstream of PSI is severely limited. We specifically show this restriction in STARCHLESS6 (sta6) mutant cells, which cannot synthesize starch when they are limited for nitrogen (growth inhibition) and subjected to a dark-to-light transition. This restriction represents a form of photosynthetic control that causes diminished electron flow to PSI and thereby prevents PSI photodamage but does not appear to rely on a ΔpH. Furthermore, when electron flow is restricted, the plastid alternative oxidase (PTOX) becomes active, functioning as an electron valve that dissipates some excitation energy absorbed by PSII and allows the formation of a proton motive force (PMF) that would drive some ATP production (potentially sustaining PSII repair and nonphotochemical quenching [NPQ]). The restriction at the Cyt b6f complex can be gradually relieved with continued illumination. This study provides insights into how PET responds to a marked reduction in availability of downstream electron acceptors and the protective mechanisms involved.
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Affiliation(s)
- Shai Saroussi
- Department of Plant Biology, The Carnegie Institution for Science, Stanford, CA 94305, USA
| | - Petra Redekop
- Department of Plant Biology, The Carnegie Institution for Science, Stanford, CA 94305, USA
| | - Devin A J Karns
- Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO 80401, USA
| | - Dylan C Thomas
- Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO 80401, USA
| | - Tyler M Wittkopp
- Department of Plant Biology, The Carnegie Institution for Science, Stanford, CA 94305, USA
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Matthew C Posewitz
- Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO 80401, USA
| | - Arthur R Grossman
- Department of Plant Biology, The Carnegie Institution for Science, Stanford, CA 94305, USA
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13
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Cantrell M, Cano M, Sebesta J, Paddock T, Xiong W, Chou KJ, Yu J. Manipulation of glycogen and sucrose synthesis increases photosynthetic productivity in cyanobacteria. Front Microbiol 2023; 14:1124274. [PMID: 37275163 PMCID: PMC10233058 DOI: 10.3389/fmicb.2023.1124274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 05/05/2023] [Indexed: 06/07/2023] Open
Abstract
Photosynthetic productivity is limited by low energy conversion efficiency in naturally evolved photosynthetic organisms, via multiple mechanisms that are not fully understood. Here we show evidence that extends recent findings that cyanobacteria use "futile" cycles in the synthesis and degradation of carbon compounds to dissipate ATP. Reduction of the glycogen cycle or the sucrose cycle in the model cyanobacterium Synechocystis 6803 led to redirection of cellular energy toward faster growth under simulated outdoor light conditions in photobioreactors that was accompanied by higher energy charge [concentration ratio of ATP/(ATP + ADP)]. Such manipulation of energy metabolism may have potential in engineering microalgal chassis cells to increase productivity of biomass or target metabolites.
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14
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Eilertsen HC, Strømholt J, Bergum JS, Eriksen GK, Ingebrigtsen R. Mass Cultivation of Microalgae: II. A Large Species Pulsing Blue Light Concept. BIOTECH 2023; 12:biotech12020040. [PMID: 37218757 DOI: 10.3390/biotech12020040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 05/14/2023] [Accepted: 05/15/2023] [Indexed: 05/24/2023] Open
Abstract
If mass cultivation of photoautotrophic microalgae is to gain momentum and find its place in the new "green future", exceptional optimizations to reduce production costs must be implemented. Issues related to illumination should therefore constitute the main focus, since it is the availability of photons in time and space that drives synthesis of biomass. Further, artificial illumination (e.g., LEDs) is needed to transport enough photons into dense algae cultures contained in large photobioreactors. In the present research project, we employed short-term O2 production and 7-day batch cultivation experiments to evaluate the potential to reduce illumination light energy by applying blue flashing light to cultures of large and small diatoms. Our results show that large diatom cells allow more light penetration for growth compared to smaller cells. PAR (400-700 nm) scans yielded twice as much biovolume-specific absorbance for small biovolume (avg. 7070 μm3) than for large biovolume (avg. 18,703 μm3) cells. The dry weight (DW) to biovolume ratio was 17% lower for large than small cells, resulting in a DW specific absorbance that was 1.75 times higher for small cells compared to large cells. Blue 100 Hz square flashing light yielded the same biovolume production as blue linear light in both the O2 production and batch experiments at the same maximum light intensities. We therefore suggest that, in the future, more focus should be placed on researching optical issues in photobioreactors, and that cell size and flashing blue light should be central in this.
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Affiliation(s)
- Hans Chr Eilertsen
- Norwegian College of Fishery Science, UiT The Arctic University of Norway, N-9037 Tromsø, Norway
- Finnfjord AS, N-9305 Finnsnes, Norway
| | | | | | - Gunilla Kristina Eriksen
- Norwegian College of Fishery Science, UiT The Arctic University of Norway, N-9037 Tromsø, Norway
| | - Richard Ingebrigtsen
- Norwegian College of Fishery Science, UiT The Arctic University of Norway, N-9037 Tromsø, Norway
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15
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Zhou Q, Yamamoto H, Shikanai T. Distinct contribution of two cyclic electron transport pathways to P700 oxidation. PLANT PHYSIOLOGY 2023; 192:326-341. [PMID: 36477622 PMCID: PMC10152692 DOI: 10.1093/plphys/kiac557] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 11/09/2022] [Accepted: 11/10/2022] [Indexed: 05/03/2023]
Abstract
Cyclic electron transport (CET) around Photosystem I (PSI) acidifies the thylakoid lumen and downregulates electron transport at the cytochrome b6f complex. This photosynthetic control is essential for oxidizing special pair chlorophylls (P700) of PSI for PSI photoprotection. In addition, CET depending on the PROTON GRADIENT REGULATION 5 (PGR5) protein oxidizes P700 by moving a pool of electrons from the acceptor side of PSI to the plastoquinone pool. This model of the acceptor-side regulation was proposed on the basis of the phenotype of the Arabidopsis (Arabidopsis thaliana) pgr5-1 mutant expressing Chlamydomonas (Chlamydomonas reinhardtii) plastid terminal oxidase (CrPTOX2). In this study, we extended the research including the Arabidopsis chlororespiratory reduction 2-2 (crr2-2) mutant defective in another CET pathway depending on the chloroplast NADH dehydrogenase-like (NDH) complex. Although the introduction of CrPTOX2 did not complement the defect in the acceptor-side regulation by PGR5, the function of the NDH complex was complemented except for its reverse reaction during the induction of photosynthesis. We evaluated the impact of CrPTOX2 under fluctuating light intensity in the wild-type, pgr5-1 and crr2-2 backgrounds. In the high-light period, both PGR5- and NDH-dependent CET were involved in the induction of photosynthetic control, whereas PGR5-dependent CET preferentially contributed to the acceptor-side regulation. On the contrary, the NDH complex probably contributed to the acceptor-side regulation in the low-light period but not in the high-light period. We evaluated the sensitivity of PSI to fluctuating light and clarified that acceptor-side regulation was necessary for PSI photoprotection by oxidizing P700 under high light.
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Affiliation(s)
- Qi Zhou
- Department of Botany, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Hiroshi Yamamoto
- 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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16
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Novel Insights into the Contribution of Cyclic Electron Flow to Cotton Bracts in Response to High Light. Int J Mol Sci 2023; 24:ijms24065589. [PMID: 36982664 PMCID: PMC10054306 DOI: 10.3390/ijms24065589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Revised: 02/28/2023] [Accepted: 03/06/2023] [Indexed: 03/17/2023] Open
Abstract
Cyclic electron flow around photosystem I (CEF-PSI) is shown to be an important protective mechanism to photosynthesis in cotton leaves. However, it is still unclear how CEF-PSI is regulated in non-foliar green photosynthetic tissues such as bracts. In order to learn more about the regulatory function of photoprotection in bracts, we investigated the CEF-PSI attributes in Yunnan 1 cotton genotypes (Gossypium bar-badense L.) between leaves and bracts. Our findings demonstrated that cotton bracts possessed PROTON GRADIENT REGULATION5 (PGR5)-mediated and the choroplastic NAD(P)H dehydrogenase (NDH)-mediated CEF-PSI by the same mechanism as leaves, albeit at a lower rate than in leaves. The ATP synthase activity of bracts was also lower, while the proton gradient across thylakoid membrane (ΔpH), rate of synthesis of zeaxanthin, and heat dissipation were higher than those of the leaves. These results imply that cotton leaves under high light conditions primarily depend on CEF to activate ATP synthase and optimize ATP/NADPH. In contrast, bracts mainly protect photosynthesis by establishing a ΔpH through CEF to stimulate the heat dissipation process.
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17
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Schiphorst C, Koeman C, Caracciolo L, Staring K, Theeuwen TPJM, Driever SM, Harbinson J, Wientjes E. The effects of different daily irradiance profiles on Arabidopsis growth, with special attention to the role of PsbS. FRONTIERS IN PLANT SCIENCE 2023; 14:1070218. [PMID: 36968375 PMCID: PMC10035889 DOI: 10.3389/fpls.2023.1070218] [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: 10/14/2022] [Accepted: 02/03/2023] [Indexed: 06/18/2023]
Abstract
In nature, light is never constant, while in the controlled environments used for vertical farming, in vitro propagation, or plant production for scientific research, light intensity is often kept constant during the photoperiod. To investigate the effects on plant growth of varying irradiance during the photoperiod, we grew Arabidopsis thaliana under three irradiance profiles: a square-wave profile, a parabolic profile with gradually increasing and subsequently decreasing irradiance, and a regime comprised of rapid fluctuations in irradiance. The daily integral of irradiance was the same for all three treatments. Leaf area, plant growth rate, and biomass at time of harvest were compared. Plants grown under the parabolic profile had the highest growth rate and biomass. This could be explained by a higher average light-use efficiency for carbon dioxide fixation. Furthermore, we compared the growth of wild type plants with that of the PsbS-deficient mutant npq4. PsbS triggers the fast non-photochemical quenching process (qE) that protects PSII from photodamage during sudden increases in irradiance. Based mainly on field and greenhouse experiments, the current consensus is that npq4 mutants grow more slowly in fluctuating light. However, our data show that this is not the case for several forms of fluctuating light conditions under otherwise identical controlled-climate room conditions.
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Affiliation(s)
- Christo Schiphorst
- Laboratory of Biophysics, Wageningen University & Research, Wageningen, Netherlands
| | - Cas Koeman
- Laboratory of Biophysics, Wageningen University & Research, Wageningen, Netherlands
| | - Ludovico Caracciolo
- Laboratory of Biophysics, Wageningen University & Research, Wageningen, Netherlands
| | - Koen Staring
- Laboratory of Biophysics, Wageningen University & Research, Wageningen, Netherlands
| | | | - Steven M. Driever
- Centre for Crop Systems Analysis, Wageningen University & Research, Wageningen, Netherlands
| | - Jeremy Harbinson
- Laboratory of Biophysics, Wageningen University & Research, Wageningen, Netherlands
| | - Emilie Wientjes
- Laboratory of Biophysics, Wageningen University & Research, Wageningen, Netherlands
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18
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Sun H, Shi Q, Liu NY, Zhang SB, Huang W. Drought stress delays photosynthetic induction and accelerates photoinhibition under short-term fluctuating light in tomato. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2023; 196:152-161. [PMID: 36706694 DOI: 10.1016/j.plaphy.2023.01.044] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 11/04/2022] [Accepted: 01/23/2023] [Indexed: 06/18/2023]
Abstract
Fluctuating light (FL) and drought stress usually occur concomitantly. However, whether drought stress affects photosynthetic performance under FL remains unknown. Here, we measured gas exchange, chlorophyll fluorescence, and P700 redox state under FL in drought-stressed tomato (Solanum lycopersicum) seedlings. Drought stress significantly delayed the induction kinetics of stomatal and mesophyll conductances after transition from low to high light and thus delayed photosynthetic induction under FL. Therefore, drought stress exacerbated the loss of carbon gain under FL. Furthermore, restriction of CO2 fixation under drought stress aggravated the over-reduction of photosystem I (PSI) upon transition from low to high light. The resulting stronger FL-induced PSI photoinhibition significantly suppressed linear electron flow and PSI photoprotection. These results indicated that drought stress not only caused a larger loss of carbon gain under FL but also accelerated FL-induced photoinhibition of PSI. Furthermore, drought stress enhanced relative cyclic electron flow in FL, which partially compensated for restricted CO2 fixation and thus favored PSI photoprotection under FL. To our knowledge, we here show new insight into how drought stress affects photosynthetic performance under FL.
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Affiliation(s)
- Hu Sun
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qi Shi
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ning-Yu Liu
- 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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19
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Kunene S, Odindo AO, Gerrano AS, Mandizvo T. Screening Bambara Groundnut ( Vigna subterranea L. Verdc) Genotypes for Drought Tolerance at the Germination Stage under Simulated Drought Conditions. PLANTS (BASEL, SWITZERLAND) 2022; 11:3562. [PMID: 36559674 PMCID: PMC9788078 DOI: 10.3390/plants11243562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 12/12/2022] [Accepted: 12/13/2022] [Indexed: 06/17/2023]
Abstract
Bambara groundnut (Vigna subterranea L. Verdc) is grown by smallholders and subsistence farmers in the marginal parts of sub-Saharan Africa. This legume is native to Africa and is cultivated throughout semi-arid sub-Saharan Africa. It is hardy and has been recognized as a nutritious food source in times of scarcity. Drought can negatively affect the germination or establishment of seedlings in the early stages of crop growth. Drought can limit the growing season of certain crops and create conditions that encourage the invasion of insects and diseases. Drought can also lead to a lack of crop yield, leading to rising food prices, shortages, and possibly malnutrition in vulnerable populations. A drought-tolerant genotype can be identified at the germination stage of Bambara groundnut by screening for drought-tolerance traits, and this knowledge can be applied to Bambara crop improvement programs to identify drought-tolerant traits during early growth phases. As an osmolyte, polyethylene glycol (PEG 6000) reduced water potential and simulated drought stress in Bambara groundnut seeds of different genotypes. Osmolytes are low-molecular-weight organic compounds that influence biological fluid properties. In this study, 24 Bambara groundnut genotypes were used. Data were collected on seed germination percentage (G%), germination velocity index (GVI), mean germination time (MGT), root dry mass (RDM), root fresh mass (RFM), and seven drought tolerance indices: mean productivity (MP), tolerance index (TOL), geometric mean productivity (GMP), stress susceptibility index (SSI), yield index (YI), yield stability index (YSI), stress tolerance index (STI) as well as seed coat color measurements. The data were applied to the mean observation of genotypes under simulated drought conditions (Ys) and the mean observation of genotypes under controlled conditions (Yp). Germination%, germination velocity index (GVI), mass germination time (MGT), and root fresh mass (RFM) differed significantly (p < 0.001) between the two stress conditions. Bambara genotypes Acc 82 and Acc 96 were found to be the most drought-tolerant.
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Affiliation(s)
- Sithembile Kunene
- School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg 3209, South Africa
| | - Alfred Oduor Odindo
- School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg 3209, South Africa
| | - Abe Shegro Gerrano
- Agricultural Research Council, Vegetables, Industrial and Medicinal Plants, Private Bag X293, Pretoria 0001, South Africa
- Department of Plant Sciences and Plant Pathology, Montana State University, Bozeman, MT 59717, USA
- Food Security and Safety Focus Area, Faculty of Natural and Agricultural Sciences, North-West University, Private Bag X2046, Mmabatho 2735, South Africa
| | - Takudzwa Mandizvo
- School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg 3209, South Africa
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20
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Xia H, Chen K, Liu L, Plenkovic-Moraj A, Sun G, Lei Y. Photosynthetic regulation in fluctuating light under combined stresses of high temperature and dehydration in three contrasting mosses. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2022; 323:111379. [PMID: 35850284 DOI: 10.1016/j.plantsci.2022.111379] [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: 03/19/2022] [Revised: 05/28/2022] [Accepted: 07/11/2022] [Indexed: 06/15/2023]
Abstract
Photosynthesis regulation is fundamental for the response to environmental dynamics, especially for bryophytes during their adaptation to terrestrial life. Alternative electron flow mediated by flavodiiron proteins (FLV) and cyclic electron flow (CEF) around photosystem I (PSI) play seminal roles in the response to abiotic stresses in mosses; nevertheless, their correlation and relative contribution to photoprotection of mosses exposed to combined stresses remain unclear. In the present study, the photosynthetic performance and recovery capacity of three moss species from different growth habitats were examined during heat and dehydration with fluctuating light. Our results showed that dehydration at 22 °C for 24 h caused little photodamage, and most of the parameters recovered to their original values after rehydration. In contrast, dehydration at 38 °C caused drastic injuries, especially to PSII, which was mainly caused by the inactivation of non-photochemical quenching (NPQ). Dehydration also induced a high accumulation of O2- and H2O2. A consistently higher CEF as well as a positive correlation between CEF and FLV was observed in resistant R. japonicum, implying CEF played a more important protective role for R. japonicum. In H. plumaeforme and P. cuspidatum, the positive relationship under mild stress switched to negative when stress became severe. Therefore, FLV pathway was sensitive to environmental fluctuations and maybe less efficient than CEF thus, readily to be lost during land colonization and evolution in angiosperms. Our work provides insights into the coordination of various pathways to fine-tune photosynthetic protection and can be used as a basis for species screening and development of breeding strategies for degraded ecosystem restoration with pioneering mosses.
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Affiliation(s)
- Hongxia Xia
- School of Life Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, China; China-Croatia "Belt and Road" Joint Laboratory on Biodiversity and Ecosystem Services, CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China
| | - Ke Chen
- School of Life Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, China
| | - Lilan Liu
- China-Croatia "Belt and Road" Joint Laboratory on Biodiversity and Ecosystem Services, CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China
| | - Anđelka Plenkovic-Moraj
- Department of Biology, Faculty of Science, University of Zagreb, Rooseveltov trg 6, Zagreb 10000, Croatia
| | - Geng Sun
- China-Croatia "Belt and Road" Joint Laboratory on Biodiversity and Ecosystem Services, CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China
| | - Yanbao Lei
- China-Croatia "Belt and Road" Joint Laboratory on Biodiversity and Ecosystem Services, CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China.
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21
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Cheng JB, Zhang SB, Wu JS, Huang W. The Dynamic Changes of Alternative Electron Flows upon Transition from Low to High Light in the Fern Cyrtomium fortune and the Gymnosperm Nageia nagi. Cells 2022; 11:cells11172768. [PMID: 36078176 PMCID: PMC9455243 DOI: 10.3390/cells11172768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 08/10/2022] [Accepted: 08/22/2022] [Indexed: 12/02/2022] Open
Abstract
In photosynthetic organisms except angiosperms, an alternative electron sink that is mediated by flavodiiron proteins (FLVs) plays the major role in preventing PSI photoinhibition while cyclic electron flow (CEF) is also essential for normal growth under fluctuating light. However, the dynamic changes of FLVs and CEF has not yet been well clarified. In this study, we measured the P700 signal, chlorophyll fluorescence, and electrochromic shift spectra in the fern Cyrtomium fortune and the gymnosperm Nageia nagi. We found that both species could not build up a sufficient proton gradient (∆pH) within the first 30 s after light abruptly increased. During this period, FLVs-dependent alternative electron flow was functional to avoid PSI over-reduction. This functional time of FLVs was much longer than previously thought. By comparison, CEF was highly activated within the first 10 s after transition from low to high light, which favored energy balancing rather than the regulation of a PSI redox state. When FLVs were inactivated during steady-state photosynthesis, CEF was re-activated to favor photoprotection and to sustain photosynthesis. These results provide new insight into how FLVs and CEF interact to regulate photosynthesis in non-angiosperms.
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Affiliation(s)
- Jun-Bin Cheng
- 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
| | - Jin-Song Wu
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
| | - Wei Huang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
- Correspondence:
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22
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Sun H, Wang XQ, Zeng ZL, Yang YJ, Huang W. Exogenous melatonin strongly affects dynamic photosynthesis and enhances water-water cycle in tobacco. FRONTIERS IN PLANT SCIENCE 2022; 13:917784. [PMID: 35991431 PMCID: PMC9381976 DOI: 10.3389/fpls.2022.917784] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 07/11/2022] [Indexed: 06/09/2023]
Abstract
Melatonin (MT), an important phytohormone synthesized naturally, was recently used to improve plant resistance against abiotic and biotic stresses. However, the effects of exogenous melatonin on photosynthetic performances have not yet been well clarified. We found that spraying of exogenous melatonin (100 μM) to leaves slightly affected the steady state values of CO2 assimilation rate (A N ), stomatal conductance (g s ) and mesophyll conductance (g m ) under high light in tobacco leaves. However, this exogenous melatonin strongly delayed the induction kinetics of g s and g m , leading to the slower induction speed of A N . During photosynthetic induction, A N is mainly limited by biochemistry in the absence of exogenous melatonin, but by CO2 diffusion conductance in the presence of exogenous melatonin. Therefore, exogenous melatonin can aggravate photosynthetic carbon loss during photosynthetic induction and should be used with care for crop plants grown under natural fluctuating light. Within the first 10 min after transition from low to high light, photosynthetic electron transport rates (ETR) for A N and photorespiration were suppressed in the presence of exogenous melatonin. Meanwhile, an important alternative electron sink, namely water-water cycle, was enhanced to dissipate excess light energy. These results indicate that exogenous melatonin upregulates water-water cycle to facilitate photoprotection. Taking together, this study is the first to demonstrate that exogenous melatonin inhibits dynamic photosynthesis and improves photoprotection in higher plants.
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Affiliation(s)
- Hu Sun
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xiao-Qian Wang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- School of Life Sciences, Northwest University, Xi’an, China
| | - Zhi-Lan Zeng
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Ying-Jie Yang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - Wei Huang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
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23
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Kim Tiam S, Comte K, Dalle C, Delagrange M, Djediat C, Ducos B, Duval C, Feilke K, Hamlaoui S, Le Manach S, Setif P, Yéprémian C, Marie B, Kirilovsky D, Gugger M, Bernard C. The success of the bloom-forming cyanobacteria Planktothrix: Genotypes variability supports variable responses to light and temperature stress. HARMFUL ALGAE 2022; 117:102285. [PMID: 35944963 DOI: 10.1016/j.hal.2022.102285] [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: 02/01/2022] [Revised: 05/05/2022] [Accepted: 06/28/2022] [Indexed: 06/15/2023]
Abstract
Cyanobacterial blooms can modify the dynamic of aquatic ecosystems and have harmful consequences for human activities. Moreover, cyanobacteria can produce a variety of cyanotoxins, including microcystins, but little is known about the role of environmental factors on the prevalence of microcystin producers in the cyanobacterial bloom dynamics. This study aimed to better understand the success of Planktothrix in various environments by unveiling the variety of strategies governing cell responses to sudden changes in light intensity and temperature. The cellular responses (photosynthesis, photoprotection, heat shock response and metabolites synthesis) of four Planktothrix strains to high-light or high-temperature were studied, focusing on how distinct ecotypes (red- or green-pigmented) and microcystin production capability affect cyanobacteria's ability to cope with such abiotic stimuli. Our results showed that high-light and high-temperature impact different cellular processes and that Planktothrix responses are heterogeneous, specific to each strain and thus, to genotype. The ability of cyanobacteria to cope with sudden increase in light intensity and temperature was not related to red- or green-pigmented ecotype or microcystin production capability. According to our results, microcystin producers do not cope better to high-light or high-temperature and microcystin content does not increase in response to such stresses.
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Affiliation(s)
- Sandra Kim Tiam
- UMR 7245 Molécules de Communication et Adaptations des Microorganismes (MCAM), Muséum National d'Histoire Naturelle, CNRS, CP 39, 57 rue Cuvier, Paris, 75005, France.
| | - Katia Comte
- UMR 7245 Molécules de Communication et Adaptations des Microorganismes (MCAM), Muséum National d'Histoire Naturelle, CNRS, CP 39, 57 rue Cuvier, Paris, 75005, France
| | - Caroline Dalle
- Institut Pasteur, Université Paris Cité, Collection of Cyanobacteria, Paris, F-75015, France
| | - Marine Delagrange
- Laboratoire de Physique Statistique, École Normale Supérieure, PSL Research University, Université Paris Diderot Sorbonne Paris-Cité, Sorbonne Université UPMC Paris 06, CNRS, High Throughput qPCR Core Facility of the ENS, IBENS, 46 rue d'Ulm, Paris,, 75005 France
| | - Chakib Djediat
- UMR 7245 Molécules de Communication et Adaptations des Microorganismes (MCAM), Muséum National d'Histoire Naturelle, CNRS, CP 39, 57 rue Cuvier, Paris, 75005, France
| | - Bertrand Ducos
- Laboratoire de Physique Statistique, École Normale Supérieure, PSL Research University, Université Paris Diderot Sorbonne Paris-Cité, Sorbonne Université UPMC Paris 06, CNRS, High Throughput qPCR Core Facility of the ENS, IBENS, 46 rue d'Ulm, Paris,, 75005 France
| | - Charlotte Duval
- UMR 7245 Molécules de Communication et Adaptations des Microorganismes (MCAM), Muséum National d'Histoire Naturelle, CNRS, CP 39, 57 rue Cuvier, Paris, 75005, France
| | - Kathleen Feilke
- Institute for Integrative Biology of the Cell (I2BC), CNRS, CEA, Université Paris-Sud, Université Paris-Saclay, Gif sur Yvette, 91198, France
| | - Sahima Hamlaoui
- UMR 7245 Molécules de Communication et Adaptations des Microorganismes (MCAM), Muséum National d'Histoire Naturelle, CNRS, CP 39, 57 rue Cuvier, Paris, 75005, France
| | - Séverine Le Manach
- UMR 7245 Molécules de Communication et Adaptations des Microorganismes (MCAM), Muséum National d'Histoire Naturelle, CNRS, CP 39, 57 rue Cuvier, Paris, 75005, France
| | - Pierre Setif
- Institute for Integrative Biology of the Cell (I2BC), CNRS, CEA, Université Paris-Sud, Université Paris-Saclay, Gif sur Yvette, 91198, France
| | - Claude Yéprémian
- UMR 7245 Molécules de Communication et Adaptations des Microorganismes (MCAM), Muséum National d'Histoire Naturelle, CNRS, CP 39, 57 rue Cuvier, Paris, 75005, France
| | - Benjamin Marie
- UMR 7245 Molécules de Communication et Adaptations des Microorganismes (MCAM), Muséum National d'Histoire Naturelle, CNRS, CP 39, 57 rue Cuvier, Paris, 75005, France
| | - Diana Kirilovsky
- Institute for Integrative Biology of the Cell (I2BC), CNRS, CEA, Université Paris-Sud, Université Paris-Saclay, Gif sur Yvette, 91198, France
| | - Muriel Gugger
- Institut Pasteur, Université Paris Cité, Collection of Cyanobacteria, Paris, F-75015, France.
| | - Cécile Bernard
- UMR 7245 Molécules de Communication et Adaptations des Microorganismes (MCAM), Muséum National d'Histoire Naturelle, CNRS, CP 39, 57 rue Cuvier, Paris, 75005, France.
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Cyclic Electron Flow-Coupled Proton Pumping in Synechocystis sp. PCC6803 Is Dependent upon NADPH Oxidation by the Soluble Isoform of Ferredoxin:NADP-Oxidoreductase. Microorganisms 2022; 10:microorganisms10050855. [PMID: 35630303 PMCID: PMC9144156 DOI: 10.3390/microorganisms10050855] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 04/13/2022] [Accepted: 04/20/2022] [Indexed: 11/17/2022] Open
Abstract
Ferredoxin:NADP-oxidoreductase (FNR) catalyzes the reversible exchange of electrons between ferredoxin (Fd) and NADP(H). Reduction of NADP+ by Fd via FNR is essential in the terminal steps of photosynthetic electron transfer, as light-activated electron flow produces NADPH for CO2 assimilation. FNR also catalyzes the reverse reaction in photosynthetic organisms, transferring electrons from NADPH to Fd, which is important in cyanobacteria for respiration and cyclic electron flow (CEF). The cyanobacterium Synechocystis sp. PCC6803 possesses two isoforms of FNR, a large form attached to the phycobilisome (FNRL) and a small form that is soluble (FNRS). While both isoforms are capable of NADPH oxidation or NADP+ reduction, FNRL is most abundant during typical growth conditions, whereas FNRS accumulates under stressful conditions that require enhanced CEF. Because CEF-driven proton pumping in the light–dark transition is due to NDH-1 complex activity and they are powered by reduced Fd, CEF-driven proton pumping and the redox state of the PQ and NADP(H) pools were investigated in mutants possessing either FNRL or FNRS. We found that the FNRS isoform facilitates proton pumping in the dark–light transition, contributing more to CEF than FNRL. FNRL is capable of providing reducing power for CEF-driven proton pumping, but only after an adaptation period to illumination. The results support that FNRS is indeed associated with increased cyclic electron flow and proton pumping, which is consistent with the idea that stress conditions create a higher demand for ATP relative to NADPH.
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25
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STN7 Kinase Is Essential for Arabidopsis thaliana Fitness under Prolonged Darkness but Not under Dark-Chilling Conditions. Int J Mol Sci 2022; 23:ijms23094531. [PMID: 35562922 PMCID: PMC9100030 DOI: 10.3390/ijms23094531] [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] [Received: 02/28/2022] [Revised: 04/11/2022] [Accepted: 04/17/2022] [Indexed: 02/04/2023] Open
Abstract
Reversible phosphorylation of photosystem II light harvesting complexes (LHCII) is a well-established protective mechanism enabling efficient response to changing light conditions. However, changes in LHCII phosphorylation were also observed in response to abiotic stress regardless of photoperiod. This study aimed to investigate the impact of dark-chilling on LHCII phosphorylation pattern in chilling-tolerant Arabidopsis thaliana and to check whether the disturbed LHCII phosphorylation process will impact the response of Arabidopsis to the dark-chilling conditions. We analyzed the pattern of LHCII phosphorylation, the organization of chlorophyll–protein complexes, and the level of chilling tolerance by combining biochemical and spectroscopy techniques under dark-chilling and dark conditions in Arabidopsis mutants with disrupted LHCII phosphorylation. Our results show that during dark-chilling, LHCII phosphorylation decreased in all examined plant lines and that no significant differences in dark-chilling response were registered in tested lines. Interestingly, after 24 h of darkness, a high increase in LHCII phosphorylation was observed, co-occurring with a significant FV/FM parameter decrease. The highest drop of FV/FM was detected in the stn7-1 line–mutant, where the LHCII is not phosphorylated, due to the lack of STN7 kinase. Our results imply that STN7 kinase activity is important for mitigating the adverse effects of prolonged darkness.
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26
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Wang H, Wang XQ, Zeng ZL, Yu H, Huang W. Photosynthesis under fluctuating light in the CAM plant Vanilla planifolia. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2022; 317:111207. [PMID: 35193751 DOI: 10.1016/j.plantsci.2022.111207] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 01/31/2022] [Accepted: 02/02/2022] [Indexed: 06/14/2023]
Abstract
Photosynthetic induction after a sudden increase in illumination affects carbon gain. Photosynthetic dynamics under fluctuating light (FL) have been widely investigated in C3 and C4 plants but are little known in CAM plants. In our present study, the chlorophyll fluorescence, P700 redox state and electrochromic shift signals were measured to examine photosynthetic characteristics under FL in the CAM orchid Vanilla planifolia. The light use efficiency was maximized in the morning but was restricted in the afternoon, indicating that the pool of malic acid dried down in the afternoon. During photosynthetic induction in the morning, electron flow through photosystem I rapidly reached the 95% of the maximum value in 4-6 min, indicating that V. planifolia showed a fast photosynthetic induction when compared with C3 and C4 plants reported previously. Upon a sudden transition from dark to actinic light, a rapid re-oxidation of P700 was observed in V. planifolia, indicating the fast outflow of electrons from PSI to alternative electron acceptors, which was attributed to the O2 photo-reduction mediated by water-water cycle. The functioning of water-water cycle prevented photosystem I over-reduction after transitioning from low to high light and thus protected PSI under FL. In the afternoon, cyclic electron flow was stimulated under FL to fine-tune photosynthetic apparatus when photosynthetic CO2 was restricted. Therefore, water-water cycle cooperates with cyclic electron flow to regulate the photosynthesis under FL in the CAM orchid V. planifolia.
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Affiliation(s)
- Hui Wang
- Spice and Beverage Research Institute, Chinese Academy of Tropical Agricultural Sciences, Wanning 571533, China
| | - Xiao-Qian Wang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; School of Life Sciences, Northwest University, Xi'an 710069, China
| | - Zhi-Lan Zeng
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Huan Yu
- Spice and Beverage Research Institute, Chinese Academy of Tropical Agricultural Sciences, Wanning 571533, China.
| | - Wei Huang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China.
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27
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Quantifying the long-term interplay between photoprotection and repair mechanisms sustaining photosystem II activity. Biochem J 2022; 479:701-717. [PMID: 35234841 DOI: 10.1042/bcj20220031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 03/01/2022] [Accepted: 03/02/2022] [Indexed: 11/17/2022]
Abstract
The photosystem II reaction centre (RCII) protein subunit D1 is the main target of light-induced damage in the thylakoid membrane. As such, it is constantly replaced with newly synthesised proteins, in a process dubbed the 'D1 repair cycle'. The mechanism of relief of excitation energy pressure on RCII, non-photochemical quenching (NPQ), is activated to prevent damage. The contribution of the D1 repair cycle and NPQ in preserving the photochemical efficiency of RCII is currently unclear. In this work, we seek to (1) quantify the relative long-term effectiveness of photoprotection offered by NPQ and the D1 repair cycle, and (2) determine the fraction of sustained decrease in RCII activity that is due to long-term protective processes. We found that while under short-term, sunfleck-mimicking illumination, NPQ is substantially more effective in preserving RCII activity than the D1 repair cycle (Plant. Cell Environ. 41, 1098-1112, 2018). Under prolonged constant illumination, its contribution is less pronounced, accounting only for up to 30% of RCII protection, while D1 repair assumes a predominant role. Exposure to a wide range of light intensities yields comparable results, highlighting the crucial role of a constant and rapid D1 turnover for the maintenance of RCII efficiency. The interplay between NPQ and D1 repair cycle is crucial to grant complete phototolerance to plants under low and moderate light intensities, and limit damage to photosystem II under high light. Additionally, we disentangled and quantified the contribution of a slowly-reversible NPQ component that does not impair RCII activity, and is therefore protective.
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28
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Yang YJ, Shi Q, Sun H, Mei RQ, Huang W. Differential Response of the Photosynthetic Machinery to Fluctuating Light in Mature and Young Leaves of Dendrobium officinale. FRONTIERS IN PLANT SCIENCE 2022; 12:829783. [PMID: 35185969 PMCID: PMC8850366 DOI: 10.3389/fpls.2021.829783] [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: 12/06/2021] [Accepted: 12/27/2021] [Indexed: 06/14/2023]
Abstract
A key component of photosynthetic electron transport chain, photosystem I (PSI), is susceptible to the fluctuating light (FL) in angiosperms. Cyclic electron flow (CEF) around PSI and water-water cycle (WWC) are both used by the epiphytic orchid Dendrobium officinale to protect PSI under FL. This study examined whether the ontogenetic stage of leaf has an impact on the photoprotective mechanisms dealing with FL. Thus, chlorophyll fluorescence and P700 signals under FL were measured in D. officinale young and mature leaves. Upon transition from dark to actinic light, a rapid re-oxidation of P700 was observed in mature leaves but disappeared in young leaves, indicating that WWC existed in mature leaves but was lacking in young leaves. After shifting from low to high light, PSI over-reduction was clearly missing in mature leaves. By comparison, young leaves showed a transient PSI over-reduction within the first 30 s, which was accompanied with highly activation of CEF. Therefore, the effect of FL on PSI redox state depends on the leaf ontogenetic stage. In mature leaves, WWC is employed to avoid PSI over-reduction. In young leaves, CEF around PSI is enhanced to compensate for the lack of WWC and thus to prevent an uncontrolled PSI over-reduction induced by FL.
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Affiliation(s)
- Ying-Jie Yang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - Qi Shi
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Hu Sun
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Ren-Qiang Mei
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - Wei Huang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- Bio-Innovation Center of DR PLANT, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
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29
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Zeng ZL, Sun H, Wang XQ, Zhang SB, Huang W. Regulation of Leaf Angle Protects Photosystem I under Fluctuating Light in Tobacco Young Leaves. Cells 2022; 11:252. [PMID: 35053368 PMCID: PMC8773500 DOI: 10.3390/cells11020252] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 12/31/2021] [Accepted: 01/04/2022] [Indexed: 02/05/2023] Open
Abstract
Fluctuating light is a typical light condition in nature and can cause selective photodamage to photosystem I (PSI). The sensitivity of PSI to fluctuating light is influenced by the amplitude of low/high light intensity. Tobacco mature leaves are tended to be horizontal to maximize the light absorption and photosynthesis, but young leaves are usually vertical to diminish the light absorption. Therefore, we tested the hypothesis that such regulation of the leaf angle in young leaves might protect PSI against photoinhibition under fluctuating light. We found that, upon a sudden increase in illumination, PSI was over-reduced in extreme young leaves but was oxidized in mature leaves. After fluctuating light treatment, such PSI over-reduction aggravated PSI photoinhibition in young leaves. Furthermore, the leaf angle was tightly correlated to the extent of PSI photoinhibition induced by fluctuating light. Therefore, vertical young leaves are more susceptible to PSI photoinhibition than horizontal mature leaves when exposed to the same fluctuating light. In young leaves, the vertical leaf angle decreased the light absorption and thus lowered the amplitude of low/high light intensity. Therefore, the regulation of the leaf angle was found for the first time as an important strategy used by young leaves to protect PSI against photoinhibition under fluctuating light. To our knowledge, we show here new insight into the photoprotection for PSI under fluctuating light in nature.
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Affiliation(s)
- Zhi-Lan Zeng
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; (Z.-L.Z.); (H.S.); (X.-Q.W.); (S.-B.Z.)
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hu Sun
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; (Z.-L.Z.); (H.S.); (X.-Q.W.); (S.-B.Z.)
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiao-Qian Wang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; (Z.-L.Z.); (H.S.); (X.-Q.W.); (S.-B.Z.)
| | - Shi-Bao Zhang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; (Z.-L.Z.); (H.S.); (X.-Q.W.); (S.-B.Z.)
| | - Wei Huang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; (Z.-L.Z.); (H.S.); (X.-Q.W.); (S.-B.Z.)
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30
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Shi Q, Sun H, Timm S, Zhang S, Huang W. Photorespiration Alleviates Photoinhibition of Photosystem I under Fluctuating Light in Tomato. PLANTS 2022; 11:plants11020195. [PMID: 35050082 PMCID: PMC8780929 DOI: 10.3390/plants11020195] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Revised: 12/30/2021] [Accepted: 12/31/2021] [Indexed: 12/12/2022]
Abstract
Fluctuating light (FL) is a typical natural light stress that can cause photodamage to photosystem I (PSI). However, the effect of growth light on FL-induced PSI photoinhibition remains controversial. Plants grown under high light enhance photorespiration to sustain photosynthesis, but the contribution of photorespiration to PSI photoprotection under FL is largely unknown. In this study, we examined the photosynthetic performance under FL in tomato (Lycopersicon esculentum) plants grown under high light (HL-plants) and moderate light (ML-plants). After an abrupt increase in illumination, the over-reduction of PSI was lowered in HL-plants, resulting in a lower FL-induced PSI photoinhibition. HL-plants displayed higher capacities for CO2 fixation and photorespiration than ML-plants. Within the first 60 s after transition from low to high light, PSII electron transport was much higher in HL-plants, but the gross CO2 assimilation rate showed no significant difference between them. Therefore, upon a sudden increase in illumination, the difference in PSII electron transport between HL- and ML-plants was not attributed to the Calvin–Benson cycle but was caused by the change in photorespiration. These results indicated that the higher photorespiration in HL-plants enhanced the PSI electron sink downstream under FL, which mitigated the over-reduction of PSI and thus alleviated PSI photoinhibition under FL. Taking together, we here for the first time propose that photorespiration acts as a safety valve for PSI photoprotection under FL.
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Affiliation(s)
- Qi Shi
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; (Q.S.); (H.S.); (S.Z.)
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hu Sun
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; (Q.S.); (H.S.); (S.Z.)
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Stefan Timm
- Plant Physiology Department, University of Rostock, D-18051 Rostock, Germany;
| | - Shibao Zhang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; (Q.S.); (H.S.); (S.Z.)
| | - Wei Huang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; (Q.S.); (H.S.); (S.Z.)
- Correspondence:
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31
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Gao S, Pinnola A, Zhou L, Zheng Z, Li Z, Bassi R, Wang G. Light-harvesting complex stress-related proteins play crucial roles in the acclimation of Physcomitrella patens under fluctuating light conditions. PHOTOSYNTHESIS RESEARCH 2022; 151:1-10. [PMID: 34468919 DOI: 10.1007/s11120-021-00874-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 08/24/2021] [Indexed: 06/13/2023]
Abstract
Photosynthetic organisms have evolved photoprotective mechanisms to acclimate to light intensity fluctuations in their natural growth environments. Photosystem (PS) II subunit S (PsbS) and light-harvesting complex (LHC) stress-related proteins (LhcSR) are essential for triggering photoprotection in vascular plants and green algae, respectively. The activity of both proteins is strongly enhanced in the moss Physcomitrella patens under high-light conditions. However, their role in regulating photosynthesis acclimation in P. patens under fluctuating light (FL) conditions is still unknown. Here, we compare the responses of wild-type (WT) P. patens and mutants lacking PsbS (psbs KO) or LhcSR1 and 2 (lhcsr KO) to FL conditions in which the low-light phases were periodically interrupted with high-light pulses. lhcsr KO mutant showed a strong reduction in growth with respect to WT and psbs KO under FL conditions. The lack of LhcSR not only decreased the level of non-photochemical quenching, resulting in an over-reduced plastoquinone pool, but also significantly increased the PSI acceptor limitation values with respect to WT and psbs KO under FL conditions. Moreover, in lhcsr KO mutant, the abundance of PSI core and PSI-LHCI complex decreased greatly under FL conditions compared with the WT and psbs KO. We proposed that LhcSR in P. patens play a crucial role in moss acclimation to dynamic light changes.
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Affiliation(s)
- Shan Gao
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Alberta Pinnola
- Department of Biology and Biotechnology 'L. Spallanzani'(DBB), University of Pavia, Pavia, Italy
| | - Lu Zhou
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
- College of Earth Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhenbing Zheng
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Zhuangyue Li
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- Department of Biology, College of Arts and Sciences, Case Western Reserve University, Cleveland, USA
| | - Roberto Bassi
- Department of Biotechnology, University of Verona, Verona, Italy
| | - Guangce Wang
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
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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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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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Fattore N, Savio S, Vera‐Vives AM, Battistuzzi M, Moro I, La Rocca N, Morosinotto T. Acclimation of photosynthetic apparatus in the mesophilic red alga Dixoniella giordanoi. PHYSIOLOGIA PLANTARUM 2021; 173:805-817. [PMID: 34171145 PMCID: PMC8596783 DOI: 10.1111/ppl.13489] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 06/17/2021] [Indexed: 06/13/2023]
Abstract
Eukaryotic algae are photosynthetic organisms capable of exploiting sunlight to fix carbon dioxide into biomass with highly variable genetic and metabolic features. Information on algae metabolism from different species is inhomogeneous and, while green algae are, in general, more characterized, information on red algae is relatively scarce despite their relevant position in eukaryotic algae diversity. Within red algae, the best-known species are extremophiles or multicellular, while information on mesophilic unicellular organisms is still lacunose. Here, we investigate the photosynthetic properties of a recently isolated seawater unicellular mesophilic red alga, Dixoniella giordanoi. Upon exposure to different illuminations, D. giordanoi shows the ability to acclimate, modulate chlorophyll content, and re-organize thylakoid membranes. Phycobilisome content is also largely regulated, leading to almost complete disassembly of this antenna system in cells grown under intense illumination. Despite the absence of a light-induced xanthophyll cycle, cells accumulate zeaxanthin upon prolonged exposure to strong light, likely contributing to photoprotection. D. giordanoi cells show the ability to perform cyclic electron transport that is enhanced under strong illumination, likely contributing to the protection of Photosystem I from over-reduction and enabling cells to survive PSII photoinhibition without negative impact on growth.
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Affiliation(s)
| | - Simone Savio
- Department of BiologyUniversity of PadovaPadovaItaly
| | | | - Mariano Battistuzzi
- Department of BiologyUniversity of PadovaPadovaItaly
- Centro di Ateneo di Studi e Attività Spaziali (CISAS) “Giuseppe Colombo”University of PadovaPadovaItaly
| | - Isabella Moro
- Department of BiologyUniversity of PadovaPadovaItaly
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Ravi Kiran B, Venkata Mohan S. Photosynthetic transients in Chlorella sorokiniana during phycoremediation of dairy wastewater under distinct light intensities. BIORESOURCE TECHNOLOGY 2021; 340:125593. [PMID: 34311176 DOI: 10.1016/j.biortech.2021.125593] [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: 05/30/2021] [Revised: 07/11/2021] [Accepted: 07/13/2021] [Indexed: 06/13/2023]
Abstract
The present study is aimed to understand the photosynthetic transients of Chlorella sorokiniana SVMBIOEN2 during treatment of dairy wastewater under different light intensities (100, 150, and 200 µmol m-2s-1) in mixotrophic mode. Light intensities showed marked influence on photosystem behavior, lipid profile, and organic pollutant removal. Analysis of Chlorophyll a fluorescence transient including Fv/Fm, ETo/RC, TRo/RC, and Abs/RC showed better photosystem efficiency at 100 µmol m-2s-1 operations. OJIP curve fitting depicted a positive L-band at 150 µmol m-2s-1 indicating lower kinetic energy of photosystem II (PSII) reaction centres at high light intensities. Better photosynthetic activity at 100 µmol m-2s-1 operations resulted in good assimilation of biomass (2.3 g L-1), carbohydrates (10.2 mg g-1), and proteins (14 mg g-1) with a significant reduction in chemical oxygen demand (85%). Phycoremediation of dairy wastewater accumulates predominantly monounsaturated fatty acids followed by polyunsaturated fatty acids showing the application of C. sorokiniana in nutraceutical and food industries.
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Affiliation(s)
- Boda Ravi Kiran
- Bioengineering and Environmental Sciences Lab, Department of Energy and Environmental Engineering (DEE), CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad 500 007, India
| | - S Venkata Mohan
- Bioengineering and Environmental Sciences Lab, Department of Energy and Environmental Engineering (DEE), CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad 500 007, India.
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Zhang JY, Zhang QH, Shuang SP, Cun Z, Wu HM, Chen JW. The Responses of Light Reaction of Photosynthesis to Dynamic Sunflecks in a Typically Shade-Tolerant Species Panax notoginseng. FRONTIERS IN PLANT SCIENCE 2021; 12:718981. [PMID: 34721452 PMCID: PMC8548386 DOI: 10.3389/fpls.2021.718981] [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: 06/01/2021] [Accepted: 09/20/2021] [Indexed: 06/13/2023]
Abstract
Light is highly heterogeneous in natural conditions, and plants need to evolve a series of strategies to acclimate the dynamic light since it is immobile. The present study aimed to elucidate the response of light reaction of photosynthesis to dynamic sunflecks in a shade-tolerant species Panax notoginseng and to examine the regulatory mechanisms involved in an adaptation to the simulated sunflecks. When P. notoginseng was exposed to the simulated sunflecks, non-photochemical quenching (NPQ) increased rapidly to the maximum value. Moreover, in response to the simulated sunflecks, there was a rapid increase in light-dependent heat dissipation quantum efficiency of photosystem II (PSII) (ΦNPQ), while the maximum quantum yield of PSII under light (F v'/F m') declined. The relatively high fluorescence and constitutive heat dissipation quantum efficiency of PSII (Φf,d) in the plants exposed to transient high light (400, 800, and 1,600 μmol m-2 s-1) was accompanied by the low effective photochemical quantum yield of PSII (ΦPSII) after the dark recovery for 15 min, whereas the plants exposed to transient low light (50 μmol m-2 s-1) has been shown to lead to significant elevation in ΦPSII after darkness recovery. Furthermore, PSII fluorescence and constitutive heat dissipation electron transfer rate (J f,d) was increased with the intensity of the simulated sunflecks, the residual absorbed energy used for the non-net carboxylative processes (J NC) was decreased when the response of electron transfer rate of NPQ pathway of PSII (J NPQ) to transient low light is restricted. In addition, the acceptor-side limitation of PSI [Y(NA)] was increased, while the donor-side limitation of photosystems I (PSI) [Y(ND)] was decreased at transient high light conditions accompanied with active cyclic electron flow (CEF). Meanwhile, when the leaves were exposed to transient high light, the xanthophyll cycle (V cycle) was activated and subsequently, the J NPQ began to increase. The de-epoxidation state [(Z + A)/(V + A + Z)] was strongly correlated with NPQ in response to the sunflecks. In the present study, a rapid engagement of lutein epoxide (Lx) after the low intensity of sunfleck together with the lower NPQ contributed to an elevation in the maximum photochemical quantum efficiency of PSII under the light. The analysis based on the correlation between the CEF and electron flow devoted to Ribulose-1, 5-bisphosphate (RuBP) oxygenation (J O) indicated that at a high light intensity of sunflecks, the electron flow largely devoted to RuBP oxygenation would contribute to the operation of the CEF. Overall, photorespiration plays an important role in regulating the CEF of the shade-tolerant species, such as P. notoginseng in response to transient high light, whereas active Lx cycle together with the decelerated NPQ may be an effective mechanism of elevating the maximum photochemical quantum efficiency of PSII under light exposure to transient low light.
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Affiliation(s)
- Jin-Yan Zhang
- College of Agronomy and Biotechnology, Yunnan Agricultural University, Kunming, China
- Key Laboratory of Medicinal Plant Biology of Yunnan Province, Yunnan Agricultural University, Kunming, China
- National and Local Joint Engineering Research Center on Germplasm Innovation and Utilization of Chinese Medicinal Materials in Southwestern China, Yunnan Agricultural University, Kunming, China
| | - Qiang-Hao Zhang
- College of Agronomy and Biotechnology, Yunnan Agricultural University, Kunming, China
- Key Laboratory of Medicinal Plant Biology of Yunnan Province, Yunnan Agricultural University, Kunming, China
- National and Local Joint Engineering Research Center on Germplasm Innovation and Utilization of Chinese Medicinal Materials in Southwestern China, Yunnan Agricultural University, Kunming, China
| | - Sheng-Pu Shuang
- College of Agronomy and Biotechnology, Yunnan Agricultural University, Kunming, China
- Key Laboratory of Medicinal Plant Biology of Yunnan Province, Yunnan Agricultural University, Kunming, China
- National and Local Joint Engineering Research Center on Germplasm Innovation and Utilization of Chinese Medicinal Materials in Southwestern China, Yunnan Agricultural University, Kunming, China
| | - Zhu Cun
- College of Agronomy and Biotechnology, Yunnan Agricultural University, Kunming, China
- Key Laboratory of Medicinal Plant Biology of Yunnan Province, Yunnan Agricultural University, Kunming, China
- National and Local Joint Engineering Research Center on Germplasm Innovation and Utilization of Chinese Medicinal Materials in Southwestern China, Yunnan Agricultural University, Kunming, China
| | - Hong-Min Wu
- College of Agronomy and Biotechnology, Yunnan Agricultural University, Kunming, China
- Key Laboratory of Medicinal Plant Biology of Yunnan Province, Yunnan Agricultural University, Kunming, China
- National and Local Joint Engineering Research Center on Germplasm Innovation and Utilization of Chinese Medicinal Materials in Southwestern China, Yunnan Agricultural University, Kunming, China
| | - Jun-Wen Chen
- College of Agronomy and Biotechnology, Yunnan Agricultural University, Kunming, China
- Key Laboratory of Medicinal Plant Biology of Yunnan Province, Yunnan Agricultural University, Kunming, China
- National and Local Joint Engineering Research Center on Germplasm Innovation and Utilization of Chinese Medicinal Materials in Southwestern China, Yunnan Agricultural University, Kunming, China
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Lei YB, Xia HX, Chen K, Plenković-Moraj A, Huang W, Sun G. Photosynthetic regulation in response to fluctuating light conditions under temperature stress in three mosses with different light requirements. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2021; 311:111020. [PMID: 34482921 DOI: 10.1016/j.plantsci.2021.111020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 08/05/2021] [Accepted: 08/07/2021] [Indexed: 06/13/2023]
Abstract
Under natural field conditions, mosses experience fluctuating light intensities combined with temperature stress. Alternative electron flow mediated by flavodiiron proteins (FLVs) and cyclic electron flow (CEF) around photosystem I (PSI) allow mosses to growth under fluctuating light conditions. However, little is known about the roles of FLVs and CEF in the regulation of photosynthesis under temperature stress combined with fluctuating light. Here, we measured chlorophyll fluorescence and P700 redox state under fluctuating light conditions at 4 °C, 20 °C, and 35 °C in three mosses with different light requirements. Upon a sudden increase in light intensity, electron flow from photosystem II initially increased and then gradually decreased at 20 °C and 35 °C, indicating that the operation of FLV-dependent flow lasted much longer than previously thought. Furthermore, the absolute rates of FLV-dependent flow and CEF were enhanced under fluctuating light at 35 °C, pointing to their important roles in photoprotection when exposed to fluctuating light at moderate high temperature. Furthermore, the downregulation of FLV activity at 4 °C was partially compensated for by enhanced CEF activity. These results suggested the subtle coordination between FLV activity and CEF under fluctuating light and temperature stress. Racomitrium japonicum and Hypnum plumaeforme, which usually grow under relatively high light levels, exhibited higher FLV activity and CEF than the shade-grown moss Plagiomnium ellipticum. Based on our results, we conclude that photosynthetic acclimation to fluctuating light and temperature stress in different mosses is largely linked to the adjustment of FLV activity and CEF.
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Affiliation(s)
- Yan-Bao Lei
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Biodiversity Conservation Key Laboratory of Sichuan Province & China-Croatia "Belt and Road" Joint Laboratory on Biodiversity and Ecosystem Services, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, China
| | - Hong-Xia Xia
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Biodiversity Conservation Key Laboratory of Sichuan Province & China-Croatia "Belt and Road" Joint Laboratory on Biodiversity and Ecosystem Services, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, China; School of Life Science and Engineering, Southwest University of Science and Technology, Mianyang, 621010, China
| | - Ke Chen
- School of Life Science and Engineering, Southwest University of Science and Technology, Mianyang, 621010, China
| | - Anđelka Plenković-Moraj
- Department of Biology, Faculty of Science, University of Zagreb, Rooseveltov trg 6, 10000, Zagreb, Croatia
| | - Wei Huang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China.
| | - Geng Sun
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Biodiversity Conservation Key Laboratory of Sichuan Province & China-Croatia "Belt and Road" Joint Laboratory on Biodiversity and Ecosystem Services, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, China.
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38
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Tan SL, Huang X, Li WQ, Zhang SB, Huang W. Elevated CO 2 Concentration Alters Photosynthetic Performances under Fluctuating Light in Arabidopsis thaliana. Cells 2021; 10:cells10092329. [PMID: 34571978 PMCID: PMC8471415 DOI: 10.3390/cells10092329] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 08/20/2021] [Accepted: 08/20/2021] [Indexed: 01/16/2023] Open
Abstract
In view of the current and expected future rise in atmospheric CO2 concentrations, we examined the effect of elevated CO2 on photoinhibition of photosystem I (PSI) under fluctuating light in Arabidopsis thaliana. At 400 ppm CO2, PSI showed a transient over-reduction within the first 30 s after transition from dark to actinic light. Under the same CO2 conditions, PSI was highly reduced after a transition from low to high light for 20 s. However, such PSI over-reduction greatly decreased when measured in 800 ppm CO2, indicating that elevated atmospheric CO2 facilitates the rapid oxidation of PSI under fluctuating light. Furthermore, after fluctuating light treatment, residual PSI activity was significantly higher in 800 ppm CO2 than in 400 ppm CO2, suggesting that elevated atmospheric CO2 mitigates PSI photoinhibition under fluctuating light. We further demonstrate that elevated CO2 does not affect PSI activity under fluctuating light via changes in non-photochemical quenching or cyclic electron transport, but rather from a rapid electron sink driven by CO2 fixation. Therefore, elevated CO2 mitigates PSI photoinhibition under fluctuating light at the acceptor rather than the donor side. Taken together, these observations indicate that elevated atmospheric CO2 can have large effects on thylakoid reactions under fluctuating light.
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Affiliation(s)
- Shun-Ling Tan
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; (S.-L.T.); (X.H.); (W.-Q.L.)
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xing Huang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; (S.-L.T.); (X.H.); (W.-Q.L.)
| | - Wei-Qi Li
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; (S.-L.T.); (X.H.); (W.-Q.L.)
| | - Shi-Bao Zhang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; (S.-L.T.); (X.H.); (W.-Q.L.)
- Correspondence: (S.-B.Z.); (W.H.)
| | - Wei Huang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; (S.-L.T.); (X.H.); (W.-Q.L.)
- Correspondence: (S.-B.Z.); (W.H.)
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39
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Dobson Z, Ahad S, Vanlandingham J, Toporik H, Vaughn N, Vaughn M, Williams D, Reppert M, Fromme P, Mazor Y. The structure of photosystem I from a high-light-tolerant cyanobacteria. eLife 2021; 10:e67518. [PMID: 34435952 PMCID: PMC8428864 DOI: 10.7554/elife.67518] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Accepted: 08/25/2021] [Indexed: 12/22/2022] Open
Abstract
Photosynthetic organisms have adapted to survive a myriad of extreme environments from the earth's deserts to its poles, yet the proteins that carry out the light reactions of photosynthesis are highly conserved from the cyanobacteria to modern day crops. To investigate adaptations of the photosynthetic machinery in cyanobacteria to excessive light stress, we isolated a new strain of cyanobacteria, Cyanobacterium aponinum 0216, from the extreme light environment of the Sonoran Desert. Here we report the biochemical characterization and the 2.7 Å resolution structure of trimeric photosystem I from this high-light-tolerant cyanobacterium. The structure shows a new conformation of the PsaL C-terminus that supports trimer formation of cyanobacterial photosystem I. The spectroscopic analysis of this photosystem I revealed a decrease in far-red absorption, which is attributed to a decrease in the number of long- wavelength chlorophylls. Using these findings, we constructed two chimeric PSIs in Synechocystis sp. PCC 6803 demonstrating how unique structural features in photosynthetic complexes can change spectroscopic properties, allowing organisms to thrive under different environmental stresses.
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Affiliation(s)
- Zachary Dobson
- School of Molecular Sciences, Arizona State UniversityTempeUnited States
- BiodesignCenter for Applied Structural Discovery, Arizona State UniversityTempeUnited States
| | - Safa Ahad
- Department of Chemistry, Purdue UniversityWest LafayetteUnited States
| | - Jackson Vanlandingham
- School of Molecular Sciences, Arizona State UniversityTempeUnited States
- BiodesignCenter for Applied Structural Discovery, Arizona State UniversityTempeUnited States
| | - Hila Toporik
- School of Molecular Sciences, Arizona State UniversityTempeUnited States
- BiodesignCenter for Applied Structural Discovery, Arizona State UniversityTempeUnited States
| | - Natalie Vaughn
- School of Molecular Sciences, Arizona State UniversityTempeUnited States
- BiodesignCenter for Applied Structural Discovery, Arizona State UniversityTempeUnited States
| | - Michael Vaughn
- School of Molecular Sciences, Arizona State UniversityTempeUnited States
- BiodesignCenter for Applied Structural Discovery, Arizona State UniversityTempeUnited States
| | - Dewight Williams
- John M. Cowley Center for High Resolution Electron Microscopy, Arizona State UniversityTempeUnited States
| | - Michael Reppert
- Department of Chemistry, Purdue UniversityWest LafayetteUnited States
| | - Petra Fromme
- School of Molecular Sciences, Arizona State UniversityTempeUnited States
- BiodesignCenter for Applied Structural Discovery, Arizona State UniversityTempeUnited States
| | - Yuval Mazor
- School of Molecular Sciences, Arizona State UniversityTempeUnited States
- BiodesignCenter for Applied Structural Discovery, Arizona State UniversityTempeUnited States
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Nagy C, Thiel K, Mulaku E, Mustila H, Tamagnini P, Aro EM, Pacheco CC, Kallio P. Comparison of alternative integration sites in the chromosome and the native plasmids of the cyanobacterium Synechocystis sp. PCC 6803 in respect to expression efficiency and copy number. Microb Cell Fact 2021; 20:130. [PMID: 34246263 PMCID: PMC8272380 DOI: 10.1186/s12934-021-01622-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 06/29/2021] [Indexed: 11/10/2022] Open
Abstract
Background Synechocystis sp. PCC 6803 provides a well-established reference point to cyanobacterial metabolic engineering as part of basic photosynthesis research, as well as in the development of next-generation biotechnological production systems. This study focused on expanding the current knowledge on genomic integration of expression constructs in Synechocystis, targeting a range of novel sites in the chromosome and in the native plasmids, together with established loci used in literature. The key objective was to obtain quantitative information on site-specific expression in reference to replicon copy numbers, which has been speculated but never compared side by side in this host. Results An optimized sYFP2 expression cassette was successfully integrated in two novel sites in Synechocystis chromosome (slr0944; sll0058) and in all four endogenous megaplasmids (pSYSM/slr5037-slr5038; pSYSX/slr6037; pSYSA/slr7023; pSYSG/slr8030) that have not been previously evaluated for the purpose. Fluorescent analysis of the segregated strains revealed that the expression levels between the megaplasmids and chromosomal constructs were very similar, and reinforced the view that highest expression in Synechocystis can be obtained using RSF1010-derived replicative vectors or the native small plasmid pCA2.4 evaluated in comparison. Parallel replicon copy number analysis by RT-qPCR showed that the expression from the alternative loci is largely determined by the gene dosage in Synechocystis, thereby confirming the dependence formerly proposed based on literature. Conclusions This study brings together nine different integrative loci in the genome of Synechocystis to demonstrate quantitative differences between target sites in the chromosome, the native plasmids, and a RSF1010-based replicative expression vector. To date, this is the most comprehensive comparison of alternative integrative sites in Synechocystis, and provides the first direct reference between expression efficiency and replicon gene dosage in the context. In the light of existing literature, the findings support the view that the small native plasmids can be notably more difficult to target than the chromosome or the megaplasmids, and that the RSF1010-derived vectors may be surprisingly well maintained under non-selective culture conditions in this cyanobacterial host. Altogether, the work broadens our views on genomic integration and the rational use of different integrative loci versus replicative plasmids, when aiming at expressing heterologous genes in Synechocystis. Supplementary Information The online version contains supplementary material available at 10.1186/s12934-021-01622-2.
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Affiliation(s)
- Csaba Nagy
- Molecular Plant Biology, Department of Life Technologies, University of Turku, Itäinen Pitkäkatu 4 C, 20520, Turku, Finland
| | - Kati Thiel
- Molecular Plant Biology, Department of Life Technologies, University of Turku, Itäinen Pitkäkatu 4 C, 20520, Turku, Finland
| | - Edita Mulaku
- Molecular Plant Biology, Department of Life Technologies, University of Turku, Itäinen Pitkäkatu 4 C, 20520, Turku, Finland
| | - Henna Mustila
- Molecular Plant Biology, Department of Life Technologies, University of Turku, Itäinen Pitkäkatu 4 C, 20520, Turku, Finland
| | - Paula Tamagnini
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135, Porto, Portugal.,IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135, Porto, Portugal.,Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, Edifício FC4, 4169-007, Porto, Portugal
| | - Eva-Mari Aro
- Molecular Plant Biology, Department of Life Technologies, University of Turku, Itäinen Pitkäkatu 4 C, 20520, Turku, Finland
| | - Catarina C Pacheco
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135, Porto, Portugal.,IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135, Porto, Portugal
| | - Pauli Kallio
- Molecular Plant Biology, Department of Life Technologies, University of Turku, Itäinen Pitkäkatu 4 C, 20520, Turku, Finland.
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Thioredoxin h2 and o1 Show Different Subcellular Localizations and Redox-Active Functions, and Are Extrachloroplastic Factors Influencing Photosynthetic Performance in Fluctuating Light. Antioxidants (Basel) 2021; 10:antiox10050705. [PMID: 33946819 PMCID: PMC8147087 DOI: 10.3390/antiox10050705] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 04/26/2021] [Accepted: 04/27/2021] [Indexed: 11/24/2022] Open
Abstract
Arabidopsis contains eight different h-type thioredoxins (Trx) being distributed in different cell organelles. Although Trx h2 is deemed to be confined to mitochondria, its subcellular localization and function are discussed controversially. Here, cell fractionation studies were used to clarify this question, showing Trx h2 protein to be exclusively localized in microsomes rather than mitochondria. Furthermore, Arabidopsis trxo1, trxh2 and trxo1h2 mutants were analyzed to compare the role of Trx h2 with mitochondrial Trx o1. Under medium light, trxo1 and trxo1h2 showed impaired growth, while trxh2 was similar to wild type. In line with this, trxo1 and trxo1h2 clustered differently from wild type with respect to nocturnal metabolite profiles, revealing a decrease in ascorbate and glutathione redox states. Under fluctuating light, these genotypic differences were attenuated. Instead, the trxo1h2 double mutant showed an improved NADPH redox balance, compared to wild type, accompanied by increased photosynthetic efficiency, specifically in the high-light phases. Conclusively, Trx h2 and Trx o1 are differentially localized in microsomes and mitochondria, respectively, which is associated with different redox-active functions and effects on plant growth in constant light, while there is a joint role of both Trxs in regulating NADPH redox balance and photosynthetic performance in fluctuating light.
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Huang W, Sun H, Tan SL, Zhang SB. The water-water cycle is not a major alternative sink in fluctuating light at chilling temperature. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2021; 305:110828. [PMID: 33691962 DOI: 10.1016/j.plantsci.2021.110828] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 11/30/2020] [Accepted: 01/12/2021] [Indexed: 05/13/2023]
Abstract
The water-water cycle (WWC) has the potential to alleviate photoinhibition of photosystem I (PSI) in fluctuating light (FL) at room temperature and moderate heat stress. However, it is unclear whether WWC can function as a safety valve for PSI in FL at chilling temperature. In this study, we measured P700 redox state and chlorophyll fluorescence in FL at 25 °C and 4 °C in the high WWC activity plant Dendrobium officinale. At 25 °C, the operation of WWC contributed to the rapid re-oxidation of P700 upon dark-to-light transition. However, such rapid re-oxidation of P700 was not observed at 4 °C. Upon a sudden increase in light intensity, WWC rapidly consumed excess electrons in PSI and thus avoided an over-reduction of PSI at 25 °C. On the contrary, PSI was highly reduced within the first seconds after transition from low to high light at 4 °C. Therefore, in opposite to 25 °C, the WWC is not a major alternative sink in FL at chilling temperature. Upon transition from low to high light, cyclic electron transport was highly stimulated at 4 °C when compared with 25 °C. These results indicate that D. officinale enhances cyclic electron transport to partially compensate for the inactivation of WWC in FL at 4 °C.
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Affiliation(s)
- Wei Huang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China; Bio-Innovation Center of DR PLANT, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China.
| | - Hu Sun
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shun-Ling Tan
- 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
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Coordination of Cyclic Electron Flow and Water-Water Cycle Facilitates Photoprotection under Fluctuating Light and Temperature Stress in the Epiphytic Orchid Dendrobium officinale. PLANTS 2021; 10:plants10030606. [PMID: 33806869 PMCID: PMC8004707 DOI: 10.3390/plants10030606] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 03/13/2021] [Accepted: 03/13/2021] [Indexed: 02/08/2023]
Abstract
Photosystem I (PSI) is the primary target of photoinhibition under fluctuating light (FL). Photosynthetic organisms employ alternative electron flows to protect PSI under FL. However, the understanding of the coordination of alternative electron flows under FL at temperature stresses is limited. To address this question, we measured the chlorophyll fluorescence, P700 redox state, and electrochromic shift signal in leaves of Dendrobium officinale exposed to FL at 42 °C, 25 °C, and 4 °C. Upon a sudden increase in illumination at 42 °C and 25 °C, the water-water cycle (WWC) consumed a significant fraction of the extra reducing power, and thus avoided an over-reduction of PSI. However, WWC was inactivated at 4 °C, leading to an over-reduction of PSI within the first seconds after light increased. Therefore, the role of WWC under FL is largely dependent on temperature conditions. After an abrupt increase in light intensity, cyclic electron flow (CEF) around PSI was stimulated at any temperature. Therefore, CEF and WWC showed different temperature responses under FL. Furthermore, the enhancement of CEF and WWC at 42 °C quickly generated a sufficient trans-thylakoid proton gradient (ΔpH). The inactivation of WWC at 4 °C was partially compensated for by an increased CEF activity. These findings indicate that CEF and WWC coordinate to protect PSI under FL at temperature stresses.
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Yu L, Fan J, Zhou C, Xu C. Chloroplast lipid biosynthesis is fine-tuned to thylakoid membrane remodeling during light acclimation. PLANT PHYSIOLOGY 2021; 185:94-107. [PMID: 33631801 PMCID: PMC8133659 DOI: 10.1093/plphys/kiaa013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 10/21/2020] [Indexed: 05/29/2023]
Abstract
Reprogramming metabolism, in addition to modifying the structure and function of the photosynthetic machinery, is crucial for plant acclimation to changing light conditions. One of the key acclimatory responses involves reorganization of the photosynthetic membrane system including changes in thylakoid stacking. Glycerolipids are the main structural component of thylakoids and their synthesis involves two main pathways localized in the plastid and the endoplasmic reticulum (ER); however, the role of lipid metabolism in light acclimation remains poorly understood. We found that fatty acid synthesis, membrane lipid content, the plastid lipid biosynthetic pathway activity, and the degree of thylakoid stacking were significantly higher in plants grown under low light compared with plants grown under normal light. Plants grown under high light, on the other hand, showed a lower rate of fatty acid synthesis, a higher fatty acid flux through the ER pathway, higher triacylglycerol content, and thylakoid membrane unstacking. We additionally demonstrated that changes in rates of fatty acid synthesis under different growth light conditions are due to post-translational regulation of the plastidic acetyl-CoA carboxylase activity. Furthermore, Arabidopsis mutants defective in one of the two glycerolipid biosynthetic pathways displayed altered growth patterns and a severely reduced ability to remodel thylakoid architecture, particularly under high light. Overall, this study reveals how plants fine-tune fatty acid and glycerolipid biosynthesis to cellular metabolic needs in response to long-term changes in light conditions, highlighting the importance of lipid metabolism in light acclimation.
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Affiliation(s)
- Linhui Yu
- Biology Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Jilian Fan
- Biology Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Chao Zhou
- Biology Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Changcheng Xu
- Biology Department, Brookhaven National Laboratory, Upton, New York 11973, USA
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Shahinnia F, Tula S, Hensel G, Reiahisamani N, Nasr N, Kumlehn J, Gómez R, Lodeyro AF, Carrillo N, Hajirezaei MR. Plastid-Targeted Cyanobacterial Flavodiiron Proteins Maintain Carbohydrate Turnover and Enhance Drought Stress Tolerance in Barley. FRONTIERS IN PLANT SCIENCE 2021; 11:613731. [PMID: 33519872 PMCID: PMC7838373 DOI: 10.3389/fpls.2020.613731] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Accepted: 12/18/2020] [Indexed: 05/10/2023]
Abstract
Chloroplasts, the sites of photosynthesis in higher plants, have evolved several means to tolerate short episodes of drought stress through biosynthesis of diverse metabolites essential for plant function, but these become ineffective when the duration of the stress is prolonged. Cyanobacteria are the closest bacterial homologs of plastids with two photosystems to perform photosynthesis and to evolve oxygen as a byproduct. The presence of Flv genes encoding flavodiiron proteins has been shown to enhance stress tolerance in cyanobacteria. In an attempt to support the growth of plants exposed to drought, the Synechocystis genes Flv1 and Flv3 were expressed in barley with their products being targeted to the chloroplasts. The heterologous expression of both Flv1 and Flv3 accelerated days to heading, increased biomass, promoted the number of spikes and grains per plant, and improved the total grain weight per plant of transgenic lines exposed to drought. Improved growth correlated with enhanced availability of soluble sugars, a higher turnover of amino acids and the accumulation of lower levels of proline in the leaf. Flv1 and Flv3 maintained the energy status of the leaves in the stressed plants by converting sucrose to glucose and fructose, immediate precursors for energy production to support plant growth under drought. The results suggest that sugars and amino acids play a fundamental role in the maintenance of the energy status and metabolic activity to ensure growth and survival under stress conditions, that is, water limitation in this particular case. Engineering chloroplasts by Flv genes into the plant genome, therefore, has the potential to improve plant productivity wherever drought stress represents a significant production constraint.
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Affiliation(s)
- Fahimeh Shahinnia
- Department of Physiology and Cell Biology, Leibniz Institute of Plant Genetics and Crop Plant Research, Gatersleben, Germany
| | - Suresh Tula
- Department of Physiology and Cell Biology, Leibniz Institute of Plant Genetics and Crop Plant Research, Gatersleben, Germany
| | - Goetz Hensel
- Department of Physiology and Cell Biology, Leibniz Institute of Plant Genetics and Crop Plant Research, Gatersleben, Germany
- Division of Molecular Biology, Centre of the Region Hana for Biotechnological and Agriculture Research, Faculty of Science, Palacký University, Olomouc, Czechia
| | - Narges Reiahisamani
- Department of Physiology and Cell Biology, Leibniz Institute of Plant Genetics and Crop Plant Research, Gatersleben, Germany
| | - Nasrin Nasr
- Department of Physiology and Cell Biology, Leibniz Institute of Plant Genetics and Crop Plant Research, Gatersleben, Germany
- Department of Biology, Payame Noor University, Teheran, Iran
| | - Jochen Kumlehn
- Department of Physiology and Cell Biology, Leibniz Institute of Plant Genetics and Crop Plant Research, Gatersleben, Germany
| | - Rodrigo Gómez
- Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Anabella F. Lodeyro
- Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Néstor Carrillo
- Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Mohammad R. Hajirezaei
- Department of Physiology and Cell Biology, Leibniz Institute of Plant Genetics and Crop Plant Research, Gatersleben, Germany
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Nishioka K, Kato Y, Ozawa SI, Takahashi Y, Sakamoto W. Phos-tag-based approach to study protein phosphorylation in the thylakoid membrane. PHOTOSYNTHESIS RESEARCH 2021; 147:107-124. [PMID: 33269435 PMCID: PMC7728655 DOI: 10.1007/s11120-020-00803-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 11/19/2020] [Indexed: 06/12/2023]
Abstract
Protein phosphorylation is a fundamental post-translational modification in all organisms. In photoautotrophic organisms, protein phosphorylation is essential for the fine-tuning of photosynthesis. The reversible phosphorylation of the photosystem II (PSII) core and the light-harvesting complex of PSII (LHCII) contribute to the regulation of photosynthetic activities. Besides the phosphorylation of these major proteins, recent phosphoproteomic analyses have revealed that several proteins are phosphorylated in the thylakoid membrane. In this study, we utilized the Phos-tag technology for a comprehensive assessment of protein phosphorylation in the thylakoid membrane of Arabidopsis. Phos-tag SDS-PAGE enables the mobility shift of phosphorylated proteins compared with their non-phosphorylated isoform, thus differentiating phosphorylated proteins from their non-phosphorylated isoforms. We extrapolated this technique to two-dimensional (2D) SDS-PAGE for detecting protein phosphorylation in the thylakoid membrane. Thylakoid proteins were separated in the first dimension by conventional SDS-PAGE and in the second dimension by Phos-tag SDS-PAGE. In addition to the isolation of major phosphorylated photosynthesis-related proteins, 2D Phos-tag SDS-PAGE enabled the detection of several minor phosphorylated proteins in the thylakoid membrane. The analysis of the thylakoid kinase mutants demonstrated that light-dependent protein phosphorylation was mainly restricted to the phosphorylation of the PSII core and LHCII proteins. Furthermore, we assessed the phosphorylation states of the structural domains of the thylakoid membrane, grana core, grana margin, and stroma lamella. Overall, these results demonstrated that Phos-tag SDS-PAGE is a useful biochemical tool for studying in vivo protein phosphorylation in the thylakoid membrane protein.
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Affiliation(s)
- Keiji Nishioka
- Institute of Plant Science and Resources (IPSR), Okayama University, 2-20-1 Chuo, Kurashiki, Okayama, 710-0046, Japan
| | - Yusuke Kato
- Institute of Plant Science and Resources (IPSR), Okayama University, 2-20-1 Chuo, Kurashiki, Okayama, 710-0046, Japan.
- Faculty of Agriculture, Setsunan University, 45-1 Nagaotoge-cho, Hirakata, Osaka, 573-0101, Japan.
| | - Shin-Ichiro Ozawa
- Institute of Plant Science and Resources (IPSR), Okayama University, 2-20-1 Chuo, Kurashiki, Okayama, 710-0046, Japan
- Research Institute for Interdisciplinary Science, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama City, Okayama, 700-8530, Japan
| | - Yuichiro Takahashi
- Research Institute for Interdisciplinary Science, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama City, Okayama, 700-8530, Japan
| | - Wataru Sakamoto
- Institute of Plant Science and Resources (IPSR), Okayama University, 2-20-1 Chuo, Kurashiki, Okayama, 710-0046, Japan.
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Divergence of photosynthetic strategies amongst marine diatoms. PLoS One 2020; 15:e0244252. [PMID: 33370327 PMCID: PMC7769462 DOI: 10.1371/journal.pone.0244252] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 12/07/2020] [Indexed: 11/19/2022] Open
Abstract
Marine phytoplankton, and in particular diatoms, are responsible for almost half of all primary production on Earth. Diatom species thrive from polar to tropical waters and across light environments that are highly complex to relatively benign, and so have evolved highly divergent strategies for regulating light capture and utilization. It is increasingly well established that diatoms have achieved such successful ecosystem dominance by regulating excitation energy available for generating photosynthetic energy via highly flexible light harvesting strategies. However, how different light harvesting strategies and downstream pathways for oxygen production and consumption interact to balance excitation pressure remains unknown. We therefore examined the responses of three diatom taxa adapted to inherently different light climates (estuarine Thalassioisira weissflogii, coastal Thalassiosira pseudonana and oceanic Thalassiosira oceanica) during transient shifts from a moderate to high growth irradiance (85 to 1200 μmol photons m-2 s-1). Transient high light exposure caused T. weissflogii to rapidly downregulate PSII with substantial nonphotochemical quenching, protecting PSII from inactivation or damage, and obviating the need for induction of O2 consuming (light-dependent respiration, LDR) pathways. In contrast, T. oceanica retained high excitation pressure on PSII, but with little change in RCII photochemical turnover, thereby requiring moderate repair activity and greater reliance on LDR. T. pseudonana exhibited an intermediate response compared to the other two diatom species, exhibiting some downregulation and inactivation of PSII, but high repair of PSII and induction of reversible PSII nonphotochemical quenching, with some LDR. Together, these data demonstrate a range of strategies for balancing light harvesting and utilization across diatom species, which reflect their adaptation to sustain photosynthesis under environments with inherently different light regimes.
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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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Water oxidation by photosystem II is the primary source of electrons for sustained H 2 photoproduction in nutrient-replete green algae. Proc Natl Acad Sci U S A 2020; 117:29629-29636. [PMID: 33168746 PMCID: PMC7703569 DOI: 10.1073/pnas.2009210117] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Photosynthetic H2 production in the green alga Chlamydomonas reinhardtii is catalyzed by O2-sensitive [FeFe]-hydrogenases, which accept electrons from photosynthetically reduced ferredoxin and reduce protons to H2. Since the process occurs downstream of photosystem I, the contribution of photosystem II (PSII) in H2 photoproduction has long been a subject of debate. Indeed, water oxidation by PSII results in O2 accumulation in chloroplasts, which inhibits H2 evolution. Therefore, clear evidence for direct water biophotolysis resulting in simultaneous H2 and O2 releases in algae has never been presented. This paper demonstrates that sustained H2 photoproduction in C. reinhardtii is directly linked to PSII-dependent water oxidation and brings insights into regulation of PSII activity and H2 production by CO2/HCO3– under microoxic conditions. The unicellular green alga Chlamydomonas reinhardtii is capable of photosynthetic H2 production. H2 evolution occurs under anaerobic conditions and is difficult to sustain due to 1) competition between [FeFe]-hydrogenase (H2ase), the key enzyme responsible for H2 metabolism in algae, and the Calvin–Benson–Bassham (CBB) cycle for photosynthetic reductants and 2) inactivation of H2ase by O2 coevolved in photosynthesis. Recently, we achieved sustainable H2 photoproduction by shifting algae from continuous illumination to a train of short (1 s) light pulses, interrupted by longer (9 s) dark periods. This illumination regime prevents activation of the CBB cycle and redirects photosynthetic electrons to H2ase. Employing membrane-inlet mass spectrometry and H218O, we now present clear evidence that efficient H2 photoproduction in pulse-illuminated algae depends primarily on direct water biophotolysis, where water oxidation at the donor side of photosystem II (PSII) provides electrons for the reduction of protons by H2ase downstream of photosystem I. This occurs exclusively in the absence of CO2 fixation, while with the activation of the CBB cycle by longer (8 s) light pulses the H2 photoproduction ceases and instead a slow overall H2 uptake is observed. We also demonstrate that the loss of PSII activity in DCMU-treated algae or in PSII-deficient mutant cells can be partly compensated for by the indirect (PSII-independent) H2 photoproduction pathway, but only for a short (<1 h) period. Thus, PSII activity is indispensable for a sustained process, where it is responsible for more than 92% of the final H2 yield.
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50
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Leister D. Alternative electron pathways in photosynthesis: strength in numbers. THE NEW PHYTOLOGIST 2020; 228:1166-1168. [PMID: 32978961 DOI: 10.1111/nph.16911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Affiliation(s)
- Dario Leister
- Plant Molecular Biology (Botany), Faculty of Biology, Ludwig-Maximilians University Munich, Planegg-Martinsried, Munich, D-82152, Germany
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