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Kula-Maximenko M, Niewiadomska E, Maksymowicz A, Ostrowska A, Oklestkova J, Pěnčík A, Janeczko A. Insight into Details of the Photosynthetic Light Reactions and Selected Metabolic Changes in Tomato Seedlings Growing under Various Light Spectra. Int J Mol Sci 2021; 22:ijms222111517. [PMID: 34768948 PMCID: PMC8584210 DOI: 10.3390/ijms222111517] [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: 08/30/2021] [Revised: 10/15/2021] [Accepted: 10/21/2021] [Indexed: 11/28/2022] Open
Abstract
The objective of our study was to characterise the growth of tomato seedlings under various light spectra, but special attention has been paid to gaining a deeper insight into the details of photosynthetic light reactions. The following light combinations (generated by LEDs, constant light intensity at 300 μmol m−2 s−1) were used: blue/red light; blue/red light + far red; blue/red light + UV; white light that was supplemented with green, and white light that was supplemented with blue. Moreover, two combinations of white light for which the light intensity was changed by imitating the sunrise, sunset, and moon were also tested. The reference point was also light generated by high pressure sodium lamps (HPS). Plant growth/morphological parameters under various light conditions were only partly correlated with the photosynthetic efficiency of PSI and PSII. Illumination with blue/red as the main components had a negative effect on the functioning of PSII compared to the white light and HPS-generated light. On the other hand, the functioning of PSI was especially negatively affected under the blue/red light that was supplemented with FR. The FT-Raman studies showed that the general metabolic profile of the leaves (especially proteins and β-carotene) was similar in the plants that were grown under the HPS and under the LED-generated white light for which the light intensity changed during a day. The effect of various light conditions on the leaf hormonal balance (auxins, brassinosteroids) is also discussed.
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Affiliation(s)
- Monika Kula-Maximenko
- Polish Academy of Sciences, The Franciszek Górski Institute of Plant Physiology, Niezapominajek 21, 30-239 Cracow, Poland; (M.K.-M.); (E.N.); (A.M.); (A.O.)
| | - Ewa Niewiadomska
- Polish Academy of Sciences, The Franciszek Górski Institute of Plant Physiology, Niezapominajek 21, 30-239 Cracow, Poland; (M.K.-M.); (E.N.); (A.M.); (A.O.)
| | - Anna Maksymowicz
- Polish Academy of Sciences, The Franciszek Górski Institute of Plant Physiology, Niezapominajek 21, 30-239 Cracow, Poland; (M.K.-M.); (E.N.); (A.M.); (A.O.)
| | - Agnieszka Ostrowska
- Polish Academy of Sciences, The Franciszek Górski Institute of Plant Physiology, Niezapominajek 21, 30-239 Cracow, Poland; (M.K.-M.); (E.N.); (A.M.); (A.O.)
| | - Jana Oklestkova
- Laboratory of Growth Regulators, Faculty of Science and Institute of Experimental Botany of the Czech Academy of Sciences, Palacký University, Šlechtitelů 27, CZ-78371 Olomouc, Czech Republic; (J.O.); (A.P.)
| | - Aleš Pěnčík
- Laboratory of Growth Regulators, Faculty of Science and Institute of Experimental Botany of the Czech Academy of Sciences, Palacký University, Šlechtitelů 27, CZ-78371 Olomouc, Czech Republic; (J.O.); (A.P.)
| | - Anna Janeczko
- Polish Academy of Sciences, The Franciszek Górski Institute of Plant Physiology, Niezapominajek 21, 30-239 Cracow, Poland; (M.K.-M.); (E.N.); (A.M.); (A.O.)
- Correspondence:
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Mishra KB, Mishra A, Kubásek J, Urban O, Heyer AG. Low temperature induced modulation of photosynthetic induction in non-acclimated and cold-acclimated Arabidopsis thaliana: chlorophyll a fluorescence and gas-exchange measurements. PHOTOSYNTHESIS RESEARCH 2019; 139:123-143. [PMID: 30306531 DOI: 10.1007/s11120-018-0588-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 09/24/2018] [Indexed: 05/23/2023]
Abstract
Cold acclimation modifies the photosynthetic machinery and enables plants to survive at sub-zero temperatures, whereas in warm habitats, many species suffer even at non-freezing temperatures. We have measured chlorophyll a fluorescence (ChlF) and CO2 assimilation to investigate the effects of cold acclimation, and of low temperatures, on a cold-sensitive Arabidopsis thaliana accession C24. Upon excitation with low intensity (40 µmol photons m- 2 s- 1) ~ 620 nm light, slow (minute range) ChlF transients, at ~ 22 °C, showed two waves in the SMT phase (S, semi steady-state; M, maximum; T, terminal steady-state), whereas CO2 assimilation showed a linear increase with time. Low-temperature treatment (down to - 1.5 °C) strongly modulated the SMT phase and stimulated a peak in the CO2 assimilation induction curve. We show that the SMT phase, at ~ 22 °C, was abolished when measured under high actinic irradiance, or when 3-(3, 4-dichlorophenyl)-1, 1- dimethylurea (DCMU, an inhibitor of electron flow) or methyl viologen (MV, a Photosystem I (PSI) electron acceptor) was added to the system. Our data suggest that stimulation of the SMT wave, at low temperatures, has multiple reasons, which may include changes in both photochemical and biochemical reactions leading to modulations in non-photochemical quenching (NPQ) of the excited state of Chl, "state transitions," as well as changes in the rate of cyclic electron flow through PSI. Further, we suggest that cold acclimation, in accession C24, promotes "state transition" and protects photosystems by preventing high excitation pressure during low-temperature exposure.
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Affiliation(s)
- Kumud B Mishra
- Global Change Research Institute, Czech Academy of Sciences, Bělidla 986/4a, 603 00, Brno, Czech Republic.
- Department of Experimental Biology, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.
| | - Anamika Mishra
- Global Change Research Institute, Czech Academy of Sciences, Bělidla 986/4a, 603 00, Brno, Czech Republic
| | - Jiří Kubásek
- Global Change Research Institute, Czech Academy of Sciences, Bělidla 986/4a, 603 00, Brno, Czech Republic
| | - Otmar Urban
- Global Change Research Institute, Czech Academy of Sciences, Bělidla 986/4a, 603 00, Brno, Czech Republic
| | - Arnd G Heyer
- Department of Plant Biotechnology, Institute of Biomaterials and Biomolecular Systems, University of Stuttgart, Pfaffenwaldring 57, 70567, Stuttgart, Germany
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Pfündel EE, Latouche G, Meister A, Cerovic ZG. Linking chloroplast relocation to different responses of photosynthesis to blue and red radiation in low and high light-acclimated leaves of Arabidopsis thaliana (L.). PHOTOSYNTHESIS RESEARCH 2018; 137:105-128. [PMID: 29374806 DOI: 10.1007/s11120-018-0482-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Accepted: 01/09/2018] [Indexed: 05/16/2023]
Abstract
Low light (LL) and high light (HL)-acclimated plants of A. thaliana were exposed to blue (BB) or red (RR) light or to a mixture of blue and red light (BR) of incrementally increasing intensities. The light response of photosystem II was measured by pulse amplitude-modulated chlorophyll fluorescence and that of photosystem I by near infrared difference spectroscopy. The LL but not HL leaves exhibited blue light-specific responses which were assigned to relocation of chloroplasts from the dark to the light-avoidance arrangement. Blue light (BB and BR) decreased the minimum fluorescence ([Formula: see text]) more than RR light. This extra reduction of the [Formula: see text] was stronger than theoretically predicted for [Formula: see text] quenching by energy dissipation but actual measurement and theory agreed in RR treatments. The extra [Formula: see text] reduction was assigned to decreased light absorption of chloroplasts in the avoidance position. A maximum reduction of 30% was calculated. Increasing intensities of blue light affected the fluorescence parameters NPQ and qP to a lesser degree than red light. After correcting for the optical effects of chloroplast relocation, the NPQ responded similarly to blue and red light. The same correction method diminished the color-specific variations in qP but did not abolish it; thus strongly indicating the presence of another blue light effect which also moderates excitation pressure in PSII but cannot be ascribed to absorption variations. Only after RR exposure, a post-illumination overshoot of [Formula: see text] and fast oxidation of PSI electron acceptors occurred, thus, suggesting an electron flow from stromal reductants to the plastoquinone pool.
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Affiliation(s)
- Erhard E Pfündel
- Lehrstuhl für Botanik II der Universität Würzburg, Julius-von-Sachs Institut für Biowissenschaften, 97082, Würzburg, Germany.
- Heinz Walz GmbH, Eichenring 6, 91090, Effeltrich, Germany.
| | - Gwendal Latouche
- Université Paris-Saclay, Université Paris-Sud, Laboratoire Écologie Systématique et Évolution, UMR8079, Bât. 362, 91405, Orsay, France
- CNRS, 91405, Orsay, France
- AgroParisTech, 75231, Paris, France
| | - Armin Meister
- Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung (IPK), Corrensstraße 3, 06466, Gatersleben, Germany
| | - Zoran G Cerovic
- Université Paris-Saclay, Université Paris-Sud, Laboratoire Écologie Systématique et Évolution, UMR8079, Bât. 362, 91405, Orsay, France
- CNRS, 91405, Orsay, France
- AgroParisTech, 75231, Paris, France
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Pommerrenig B, Ludewig F, Cvetkovic J, Trentmann O, Klemens PAW, Neuhaus HE. In Concert: Orchestrated Changes in Carbohydrate Homeostasis Are Critical for Plant Abiotic Stress Tolerance. PLANT & CELL PHYSIOLOGY 2018; 59:1290-1299. [PMID: 29444312 DOI: 10.1093/pcp/pcy037] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Indexed: 06/08/2023]
Abstract
The sessile lifestyle of higher plants is accompanied by their remarkable ability to tolerate unfavorable environmental conditions. This is because, during evolution, plants developed a sophisticated repertoire of molecular and metabolic reactions to cope with changing biotic and abiotic challenges. In particular, the abiotic factors light intensity and ambient temperature are characterized by altering their amplitude within comparably short periods of time and are causative for onset of dynamic plant responses. These rapid responses in plants are also classified as 'acclimation reactions' which differ, due to their reversibility and duration, from non-reversible 'adaptation reactions'. In this review, we demonstrate the remarkable importance of stress-induced changes in carbohydrate homeostasis of plants exposed to high light or low temperatures. These changes represent a co-ordinated process comprising modifications of (i) the concentrations of selected sugars; (ii) starch turnover; (iii) intracellular sugar compartmentation; and (iv) corresponding gene expression patterns. The critical importance of these individual processes has been underlined in the recent past by the analyses of a large number of mutant plants. The outcome of these analyses raised our understanding of acclimation processes in plants per se but might even become instrumental to develop new concepts for directed breeding approaches with the aim to increase abiotic stress tolerance of crop species, which in most cases have high stress sensitivity. The latter direction of plant research is of special importance since abiotic stress stimuli strongly impact on crop productivity and are expected to become even more pronounced because of human activities which alter environmental conditions rapidly.
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Affiliation(s)
- Benjamin Pommerrenig
- University of Kaiserslautern, Plant Physiology, Erwin-Schrödinger-Str, Kaiserslautern, Germany
| | - Frank Ludewig
- Department of Biochemistry, Friedrich-Alexander University Erlangen-Nuremberg, Staudtstr. 5, Erlangen, Germany
| | - Jelena Cvetkovic
- University of Kaiserslautern, Plant Physiology, Erwin-Schrödinger-Str, Kaiserslautern, Germany
| | - Oliver Trentmann
- University of Kaiserslautern, Plant Physiology, Erwin-Schrödinger-Str, Kaiserslautern, Germany
| | - Patrick A W Klemens
- University of Kaiserslautern, Plant Physiology, Erwin-Schrödinger-Str, Kaiserslautern, Germany
| | - H Ekkehard Neuhaus
- University of Kaiserslautern, Plant Physiology, Erwin-Schrödinger-Str, Kaiserslautern, Germany
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Essemine J, Xiao Y, Qu M, Mi H, Zhu XG. Cyclic electron flow may provide some protection against PSII photoinhibition in rice (Oryza sativa L.) leaves under heat stress. JOURNAL OF PLANT PHYSIOLOGY 2017; 211:138-146. [PMID: 28199904 DOI: 10.1016/j.jplph.2017.01.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 12/24/2016] [Accepted: 01/20/2017] [Indexed: 05/08/2023]
Abstract
Previously we have shown that a quick down-regulation in PSI activity compares to that of PSII following short-term heat stress for two rice groups including C4023 and Q4149, studied herein. These accessions were identified to have different natural capacities in driving cyclic electron flow (CEF) around PSI; i.e., low CEF (lcef) and high CEF (hcef) for C4023 and Q4149, respectively. The aim of this study was to investigate whether these two lines have different mechanisms of protecting photosystem II from photodamage under heat stress. We observed a stepwise alteration in the shape of Chl a fluorescence induction (OJIP) with increasing temperature treatment. The effect of 44°C treatment on the damping in Chl a fluorescence was more pronounced in C4023 than in Q4149. Likewise, we noted a disruption in the I-step, a decline in the Fv due to a strong damping in the Fm, and a slight increase in the F0. Normalized data demonstrated that the I-step seems more susceptible to 44°C in C4023 than in Q4149. We also measured the redox states of plastocyanin (PC) and P700 by monitoring the transmission changes at 820nm (I820), and observed a disturbance in the oxidation/reduction kinetics of PC and P700. The decline in the amplitude of their oxidation was shown to be about 29% and 13% for C4023 and Q4149, respectively. The electropotential component (Δφ) of ms-DLE appeared more sensitive to temperature stress than the chemical component (ΔpH), and the impact of heat was more evident and drastic in C4023 than in Q4149. Under heat stress, we noticed a concomitant decline in the primary photochemistry of PSII as well as in both the membrane energization process and the lumen protonation for both accessions, and it is evident that heat affects these parameters more in C4023 than in Q4149. All these data suggest that higher CET can confer higher photoprotection to PSII in rice lines, which can be a desirable trait during rice breeding, especially in the context of a "warming" world.
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Affiliation(s)
- Jemaa Essemine
- CAS-Key Laboratory for Computational Biology and State Key Laboratory for Hybrid Rice, Partner Institute for Computational Biology, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Yi Xiao
- CAS-Key Laboratory for Computational Biology and State Key Laboratory for Hybrid Rice, Partner Institute for Computational Biology, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Mingnan Qu
- CAS-Key Laboratory for Computational Biology and State Key Laboratory for Hybrid Rice, Partner Institute for Computational Biology, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Hualing Mi
- National Key Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Xin-Guang Zhu
- CAS-Key Laboratory for Computational Biology and State Key Laboratory for Hybrid Rice, Partner Institute for Computational Biology, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
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Sun Y, Geng Q, Du Y, Yang X, Zhai H. Induction of cyclic electron flow around photosystem I during heat stress in grape leaves. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2017; 256:65-71. [PMID: 28167040 DOI: 10.1016/j.plantsci.2016.12.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 11/30/2016] [Accepted: 12/08/2016] [Indexed: 05/11/2023]
Abstract
Photosystem II (PSII) in plants is susceptible to high temperatures. The cyclic electron flow (CEF) around PSI is thought to protect both PSII and PSI from photodamage. However, the underlying physiological mechanisms of the photosynthetic electron transport process and the role of CEF in grape at high temperatures remain unclear. To investigate this issue, we examined the responses of PSII energy distribution, the P700 redox state and CEF to high temperatures in grape leaves. After exposing 'Cabernet Sauvignon' leaves to various temperatures (25, 30, 35, 40 and 45°C) in the light (600μmol photons m-2s-1) for 4h, the maximum quantum yield of PSII (Fv/Fm) significantly decreased at high temperatures (40 and 45°C), while the maximum photo-oxidizable P700 (Pm) was not affected. As the temperature increased, higher initial rates of increase in post-illumination Chl fluorescence were detected, which were accompanied by an increase in high energy state quenching (qE). The chloroplast NAD(P)H dehydrogenase-dependent CEF (NDH-dependent CEF) activities were different among grape cultivators. 'Gold Finger' with greater susceptibility to photoinhibition, exhibited lower NDH-dependent CEF activities under acute heat stress than a more heat tolerant 'Cabernet Sauvignon'. These results suggest that overclosure of PSII reaction centers at high temperature resulted in the photoinhibition of PSII, while the stimulation of CEF in grape played an important role in the photoprotection of PSII and PSI at high temperatures through contributing to the generation of a proton gradient.
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Affiliation(s)
- Yongjiang Sun
- State Key Lab of Crop Biology, Tai'an 271018, Shandong, China; College of Life Sciences, Shandong Agricultural University, Tai'an 271018, Shandong, China
| | - Qingwei Geng
- State Key Lab of Crop Biology, Tai'an 271018, Shandong, China; College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an 271018, Shandong, China
| | - Yuanpeng Du
- State Key Lab of Crop Biology, Tai'an 271018, Shandong, China; College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an 271018, Shandong, China
| | - Xinghong Yang
- State Key Lab of Crop Biology, Tai'an 271018, Shandong, China; College of Life Sciences, Shandong Agricultural University, Tai'an 271018, Shandong, China
| | - Heng Zhai
- State Key Lab of Crop Biology, Tai'an 271018, Shandong, China; College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an 271018, Shandong, China.
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Huang W, Yang YJ, Hu H, Cao KF, Zhang SB. Sustained Diurnal Stimulation of Cyclic Electron Flow in Two Tropical Tree Species Erythrophleum guineense and Khaya ivorensis. FRONTIERS IN PLANT SCIENCE 2016; 7:1068. [PMID: 27486473 PMCID: PMC4950474 DOI: 10.3389/fpls.2016.01068] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 07/06/2016] [Indexed: 05/04/2023]
Abstract
The photosystem II (PSII) activity of C3 plants is usually inhibited at noon associated with high light but can be repaired fast in the afternoon. However, the diurnal variation of photosystem I (PSI) activity is unknown. Although, cyclic electron flow (CEF) has been documented as an important mechanism for photosynthesis, the diurnal variation of CEF in sun leaves is little known. We determined the diurnal changes in PSI and PSII activities, light energy dissipation in PSII and the P700 redox state in two tropical tree species Erythrophleum guineense and Khaya ivorensis grown in an open field. The PSI activity (as indicated by the maximum quantity of photo-oxidizable P700) was maintained stable during the daytime. CEF was strongly activated under high light at noon, accompanying with high levels of non-photochemical quenching (NPQ) and PSI oxidation ratio. In the afternoon, CEF was maintained at a relatively high level under low light, which was accompanied with low levels of NPQ and P700 oxidation ratio. These results indicated that CEF was flexibly modulated during daytime under fluctuating light conditions. Under high light at noon, CEF-dependent generation of proton gradient across the thylakoid membranes (ΔpH) mainly contributed to photoprotection for PSI and PSII. By comparison, at low light in the afternoon, the CEF-dependent formation of ΔpH may be important for PSII repair via an additional ATP synthesis.
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Affiliation(s)
- Wei Huang
- Key Laboratory of Economic Plants and Biotechnology, Kunming Institute of Botany – Chinese Academy of Sciences, KunmingChina
- Yunnan Key Laboratory for Wild Plant ResourcesKunming, China
| | - Ying-Jie Yang
- Key Laboratory of Economic Plants and Biotechnology, Kunming Institute of Botany – Chinese Academy of Sciences, KunmingChina
- Yunnan Key Laboratory for Wild Plant ResourcesKunming, China
| | - Hong Hu
- Key Laboratory of Economic Plants and Biotechnology, Kunming Institute of Botany – Chinese Academy of Sciences, KunmingChina
- Yunnan Key Laboratory for Wild Plant ResourcesKunming, China
| | - Kun-Fang Cao
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden – Chinese Academy of SciencesMengla, China
| | - Shi-Bao Zhang
- Key Laboratory of Economic Plants and Biotechnology, Kunming Institute of Botany – Chinese Academy of Sciences, KunmingChina
- Yunnan Key Laboratory for Wild Plant ResourcesKunming, China
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Kruse J, Alfarraj S, Rennenberg H, Adams M. A novel mechanistic interpretation of instantaneous temperature responses of leaf net photosynthesis. PHOTOSYNTHESIS RESEARCH 2016; 129:43-58. [PMID: 27220614 DOI: 10.1007/s11120-016-0262-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 04/11/2016] [Indexed: 05/16/2023]
Abstract
Steady-state rates of leaf CO2 assimilation (A) in response to incubation temperature (T) are often symmetrical around an optimum temperature. A/T curves of C3 plants can thus be fitted to a modified Arrhenius equation, where the activation energy of A close to a low reference temperature is strongly correlated with the dynamic change of activation energy to increasing incubation temperature. We tested how [CO2] < current atmospheric levels and saturating light, or [CO2] at 800 µmol mol(-1) and variable light affect parameters that describe A/T curves, and how these parameters are related to known properties of temperature-dependent thylakoid electron transport. Variation of light intensity and substomatal [CO2] had no influence on the symmetry of A/T curves, but significantly affected their breadth. Thermodynamic and kinetic (physiological) factors responsible for (i) the curvature in Arrhenius plots and (ii) the correlation between parameters of a modified Arrhenius equation are discussed. We argue that the shape of A/T curves cannot satisfactorily be explained via classical concepts assuming temperature-dependent shifts between rate-limiting processes. Instead the present results indicate that any given A/T curve appears to reflect a distinct flux mode, set by the balance between linear and cyclic electron transport, and emerging from the anabolic demand for ATP relative to that for NADPH.
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Affiliation(s)
- Jörg Kruse
- Chair of Tree Physiology, Institute of Forest Sciences, Georges-Köhler-Allee 53/54, 79110, Freiburg, Germany.
| | - Saleh Alfarraj
- College of Sciences, King Saud University, P.O. Box 2455, Riyadh, 11451, Saudi Arabia
| | - Heinz Rennenberg
- Chair of Tree Physiology, Institute of Forest Sciences, Georges-Köhler-Allee 53/54, 79110, Freiburg, Germany
- College of Sciences, King Saud University, P.O. Box 2455, Riyadh, 11451, Saudi Arabia
| | - Mark Adams
- Faculty of Agriculture and Environment, The University of Sydney, Sydney, NSW, 2006, Australia
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Shikanai T. Chloroplast NDH: A different enzyme with a structure similar to that of respiratory NADH dehydrogenase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:1015-22. [DOI: 10.1016/j.bbabio.2015.10.013] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 10/21/2015] [Accepted: 10/26/2015] [Indexed: 11/28/2022]
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Yamori W, Shikanai T. Physiological Functions of Cyclic Electron Transport Around Photosystem I in Sustaining Photosynthesis and Plant Growth. ANNUAL REVIEW OF PLANT BIOLOGY 2016; 67:81-106. [PMID: 26927905 DOI: 10.1146/annurev-arplant-043015-112002] [Citation(s) in RCA: 285] [Impact Index Per Article: 35.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The light reactions in photosynthesis drive both linear and cyclic electron transport around photosystem I (PSI). Linear electron transport generates both ATP and NADPH, whereas PSI cyclic electron transport produces ATP without producing NADPH. PSI cyclic electron transport is thought to be essential for balancing the ATP/NADPH production ratio and for protecting both photosystems from damage caused by stromal overreduction. Two distinct pathways of cyclic electron transport have been proposed in angiosperms: a major pathway that depends on the PROTON GRADIENT REGULATION 5 (PGR5) and PGR5-LIKE PHOTOSYNTHETIC PHENOTYPE 1 (PGRL1) proteins, which are the target site of antimycin A, and a minor pathway mediated by the chloroplast NADH dehydrogenase-like (NDH) complex. Recently, the regulation of PSI cyclic electron transport has been recognized as essential for photosynthesis and plant growth. In this review, we summarize the possible functions and importance of the two pathways of PSI cyclic electron transport.
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Affiliation(s)
- Wataru Yamori
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan;
- Precursory Research for Embryonic Science and Technology (PRESTO) and
| | - Toshiharu Shikanai
- Core Research for Evolutionary Science and Technology (CREST), Japan Science and Technology Agency, Kawaguchi 332-0012, Japan
- Department of Botany, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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Lichen Photobionts Show Tolerance against Lichen Acids Produced by Lichen Mycobionts. Biosci Biotechnol Biochem 2014; 72:3122-7. [DOI: 10.1271/bbb.80241] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Trans-thylakoid ∆pH dependent oscillation of F(PSI)/F(PSII) under continuous irradiance in isolated thylakoids. J Bioenerg Biomembr 2013; 46:71-82. [PMID: 24214386 DOI: 10.1007/s10863-013-9533-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 10/10/2013] [Indexed: 10/26/2022]
Abstract
Energy distribution between photosystems (PSI & PSII) under prolonged and continuous white light irradiance was assessed by monitoring the progress of their fluorescence emission (FPSI/FPSII) at 77 K. Our observations indicate FPSI/FPSII to oscillate with the progress of irradiance treatments at all intensities tested (100, 200, 500, and 800 μE m(-2) S(-1)). The amplitude of the oscillation increased with the progress, whereas the periodicity of the oscillation increased with the intensity of the incident irradiance. Spectral analysis indicated fluctuation of FPSI to be the major determinant of the observed oscillation. The first rise and fall of FPSI/FPSII overlapped with phosphorylation and dephosphorylation of LHCII, but oscillation of FPSI/FPSII continued for several cycles without any further phosphorylation of LHCII. Moreover, in presence of DCMU where linear electron flow (LEF) is suppressed and LHCII phosphorylation is completely abolished, the oscillation of FPSI/FPSII was not abolished. These data indicated that LHCII phosphorylation was not essential for the observed oscillation of energy distribution between the photosystems. In contrast, in the presence of inhibitors of cyclic electron flow (CEF) like Antimycin A (AA) and rotenone, the oscillation of FPSI/FPSII was either abolished or severely dampened. Additionally, the oscillation was also abolished in presence of uncouplers like NH4Cl and nigericin that cancels the trans-thylakoid ∆pH. Thus, trans-thylakoid ∆pH, generated through CEF, appear to be an important determinant of oscillation of FPSI/FPSII in isolated thylakoids. The phenomenon of oscillation could be associated with a CEF mediated chromatic adaptation of PSI in presence of excess irradiance.
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13
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Blanco NE, Ceccoli RD, Vía MVD, Voss I, Segretin ME, Bravo-Almonacid FF, Melzer M, Hajirezaei MR, Scheibe R, Hanke GT. Expression of the minor isoform pea ferredoxin in tobacco alters photosynthetic electron partitioning and enhances cyclic electron flow. PLANT PHYSIOLOGY 2013; 161:866-79. [PMID: 23370717 PMCID: PMC3561025 DOI: 10.1104/pp.112.211078] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Accepted: 12/04/2012] [Indexed: 05/07/2023]
Abstract
Ferredoxins (Fds) are ferrosulfoproteins that function as low-potential electron carriers in plants. The Fd family is composed of several isoforms that share high sequence homology but differ in functional characteristics. In leaves, at least two isoforms conduct linear and cyclic photosynthetic electron transport around photosystem I, and mounting evidence suggests the existence of at least partial division of duties between these isoforms. To evaluate the contribution of different kinds of Fds to the control of electron fluxes along the photosynthetic electron transport chain, we overexpressed a minor pea (Pisum sativum) Fd isoform (PsFd1) in tobacco (Nicotiana tabacum) plants. The transplastomic OeFd1 plants exhibited variegated leaves and retarded growth and developmental rates. Photosynthetic studies of these plants indicated a reduction in carbon dioxide assimilation rates, photosystem II photochemistry, and linear electron flow. However, the plants showed an increase in nonphotochemical quenching, better control of excitation pressure at photosystem II, and no evidence of photoinhibition, implying a better dynamic regulation to remove excess energy from the photosynthetic electron transport chain. Finally, analysis of P700 redox status during illumination confirmed that the minor pea Fd isoform promotes enhanced cyclic flow around photosystem I. The two novel features of this work are: (1) that Fd levels achieved in transplastomic plants promote an alternative electron partitioning even under greenhouse light growth conditions, a situation that is exacerbated at higher light intensity measurements; and (2) that an alternative, minor Fd isoform has been overexpressed in plants, giving new evidence of labor division among Fd isoforms.
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Affiliation(s)
- Nicolás E Blanco
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, SE 901 87 Umea, Sweden.
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14
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Bolychevtseva YV, Elanskaya IV, Karapetyan NV. Regulation of cyclic electron transport through photosystem I in cyanobacterium Synechocystis sp. PCC 6803 mutants deficient in respiratory dehydrogenases. BIOCHEMISTRY (MOSCOW) 2011; 76:427-37. [PMID: 21585318 DOI: 10.1134/s0006297911040055] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The rate of PSI mediated cyclic electron transport was studied in wild type and mutant cells of Synechocystis sp. PCC 6803 deficient in NDH-1 (M55) or succinate dehydrogenase (SDH(-)) that are responsible for the dark reduction of the plastoquinone pool. Kinetics of P700 photooxidation and P700(+) dark reduction in the presence of 5·10(-5) M 3-(3,4-dichlorophenyl)-1,1-dimethylurea have been registered as light induced absorbance changes at 810 nm resulting from illumination of cells with 730-nm actinic light for 1 sec. It is shown that in the absence of dehydrogenases the rate of dark reduction of P700(+) in both mutants did not decrease but even increased in NDH-1-less mutant cells as compared with the rate in wild type cells. Dibromothymoquinone drastically reduced the rate of P700(+) dark reduction both in wild type and in mutant cells. Thus, the cyclic electron transfer from ferredoxin through the plastoquinone pool to P700(+), which is independent from dehydrogenases, takes place in all the types of cells. Preillumination of cells of wild type and both mutants for 30 min or anaerobic conditions resulted in delay of P700 photooxidation and acceleration of P700(+) dark reduction, while the level of photosynthesis and respiration terminal acceptors (NAD(P)(+) and oxygen) decreased. It appears that the rate of P700 photooxidation and P700(+) dark reduction in cyclic electron transport in Synechocystis wild type and mutant cells is determined by the level of NADP+ and oxygen in stroma. A possible approach to evaluation of the levels of these acceptors in vivo is proposed, based on kinetic curve parameters of P700 photoconversions induced by 730-nm light with 1-sec duration.
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Affiliation(s)
- Yu V Bolychevtseva
- Bach Institute of Biochemistry, Russian Academy of Sciences, Moscow, Russia.
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15
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Essemine J, Govindachary S, Ammar S, Bouzid S, Carpentier R. Abolition of photosystem I cyclic electron flow in Arabidopsis thaliana following thermal-stress. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2011; 49:235-43. [PMID: 21256041 DOI: 10.1016/j.plaphy.2010.11.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Revised: 10/29/2010] [Accepted: 11/02/2010] [Indexed: 05/09/2023]
Abstract
Heat tolerance of Arabidopsis thaliana (WT) and its mutants, crr2-2, lacking NADPH-dehydrogenase (Ndh-pathway), and pgr5, deficient in proton gradient regulation and/or ferredoxin-quinone-reductase (FQR-pathway), was studied from 30 to 46°C. Chlorophyll fluorescence revealed that thermal damage to photosystem II (PSII) was maximal in WT plants following short-term exposure of leaves to moderate or high temperature stress. Thermal stress impaired the photosynthetic electron flow at oxidizing and reducing sides of PSII. This was deduced from the transformation of temperature dependent OJIP to OKP patterns, changes in the relative amplitudes of K-step fluorescence rise and F(v)/F(o) ratio. The amplitude of the K-peak that corresponds to the magnitude of damage to the oxygen evolving complex (OEC) in crr2-2 mutants was about 50% of that observed in WT plants exposed to 46°C. The damage to OEC in pgr5 mutants was relatively smaller and thus their PSII complexes were more heat tolerant. P700 oxidation-reduction kinetics following heat-stress revealed that photosystem I (PSI) complexes remained oxidizable either with 10-ms multiple turn-over flashes or far-red illumination but the complementary cyclic electron flow around PSI (CEF) was abolished in both mutants. With further increase in incubation temperature, CEF was fully suppressed even in WT. Thus, P700 turn-over was not enhanced following thermal stress. Furthermore, the experimental data predicts the onset of pseudocyclic electron transport with molecular oxygen as terminal acceptor in crr2-2 and pgr5 mutants but not in wild type Arabidopsis subjected to severe thermal-stress.
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Affiliation(s)
- Jemâa Essemine
- Groupe de Recherche en Biologie Végétale (GRBV), Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada
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16
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Tsuyama M, Kobayashi Y. Reduction of the primary donor P700 of photosystem I during steady-state photosynthesis under low light in Arabidopsis. PHOTOSYNTHESIS RESEARCH 2009; 99:37-47. [PMID: 18975133 DOI: 10.1007/s11120-008-9379-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2008] [Accepted: 10/06/2008] [Indexed: 05/27/2023]
Abstract
During steady-state photosynthesis in low-light, 830-nm absorption (A(830)) by leaves was close to that in darkness in Arabidopsis, indicating that the primary donor P700 in the reaction center of photosystem I (PSI) was in reduced form. However, P700 was not fully oxidized by a saturating light pulse, suggesting the presence of a population of PSI centers with reduced P700 that remains thermodynamically stable during the application of the saturating light pulse (i.e., reduced-inactive P700). To substantiate this, the effects of methyl viologen (MV) and far-red light on P700 oxidation by the saturating light pulse were analyzed, and the cumulative effects of repetitive application of the saturating light pulse on photosynthesis were analyzed using a mutant crr2-2 with impaired PSI cyclic electron flow. We concluded that the reduced-inactive P700 in low-light as revealed by saturating light pulse indicates limitations of electron flow at the PSI acceptor side.
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Affiliation(s)
- Michito Tsuyama
- Department of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan.
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17
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Ishikawa N, Endo T, Sato F. Electron transport activities of Arabidopsis thaliana mutants with impaired chloroplastic NAD(P)H dehydrogenase. JOURNAL OF PLANT RESEARCH 2008; 121:521-526. [PMID: 18683022 DOI: 10.1007/s10265-008-0180-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2008] [Accepted: 06/16/2008] [Indexed: 05/26/2023]
Abstract
The activities of electron transport are compared between wild-type Arabidopsis and two Arabidopsis mutants deficient for the chloroplastic NAD(P)H dehydrogenase (NDH) which catalyzes cyclic electron transport around photosystem I. The quantum yield of photosystem II and the degree of non-photochemical quenching of chlorophyll fluorescence were of similar levels in the two NDH-deficient mutants and the wild type under non-stressed standard growth conditions. Stromal over-reduction was induced in Arabidopsis NDH mutants with high light treatment, as is the case in tobacco NDH mutants. However, unlike tobacco mutants, photoinhibition was not observed in the Arabidopsis NDH mutants.
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Affiliation(s)
- Noriko Ishikawa
- Department of Plant Genes and Totipotency, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8502, Japan
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18
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Voss I, Koelmann M, Wojtera J, Holtgrefe S, Kitzmann C, Backhausen JE, Scheibe R. Knockout of major leaf ferredoxin reveals new redox-regulatory adaptations in Arabidopsis thaliana. PHYSIOLOGIA PLANTARUM 2008; 133:584-98. [PMID: 18494733 DOI: 10.1111/j.1399-3054.2008.01112.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Ferredoxins are the major distributors for electrons to the various acceptor systems in plastids. In green tissues, ferredoxins are reduced by photosynthetic electron flow in the light, while in heterotrophic tissues, nicotinamide adenine dinucleotide (reduced) (NADPH) generated in the oxidative pentose-phosphate pathway (OPP) is the reductant. We have used a Ds-T-DNA insertion line of Arabidopsis thaliana for the gene encoding the major leaf ferredoxin (Fd2, At1g60950) to create a situation of high electron pressure in the thylakoids. Although these plants (Fd2-KO) possess only the minor fraction of leaf Fd1 (At1g10960), they grow photoautotrophically on soil, but with a lower growth rate and less chlorophyll. The more oxidized conditions in the stroma due to the formation of reactive oxygen species are causing a re-adjustment of the redox state in these plants that helps them to survive even under high light. Redox homeostasis is achieved by regulation at both, the post-translational and the transcriptional level. Over-reduction of the electron transport chain leads to increased transcription of the malate-valve enzyme NADP-malate dehydrogenase (MDH), and the oxidized stroma leads to an increased transcription of the OPP enzyme glucose-6-P dehydrogenase. In isolated spinach chloroplasts, oxidized conditions give rise to a decreased activation state of NADP-MDH and an activation of glucose-6-P dehydrogenase even in the light. In Fd2-KO plants, NADPH-requiring antioxidant systems are upregulated. These adjustments must be caused by plastid signals, and they prevent oxidative damage under rather severe conditions.
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Affiliation(s)
- Ingo Voss
- Department of Plant Physiology, Faculty of Biology and Chemistry, University of Osnabrueck, D-49069 Osnabrueck, Germany
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19
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Hanke GT, Endo T, Satoh F, Hase T. Altered photosynthetic electron channelling into cyclic electron flow and nitrite assimilation in a mutant of ferredoxin:NADP(H) reductase. PLANT, CELL & ENVIRONMENT 2008; 31:1017-28. [PMID: 18410491 DOI: 10.1111/j.1365-3040.2008.01814.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The mechanism by which plants regulate channelling of photosynthetically derived electrons into different areas of chloroplast metabolism remains obscure. Possible fates of such electrons include use in carbon assimilation, nitrogen assimilation and redox signalling pathways, or return to the plastoquinone pool through cyclic electron flow. In higher plants, these electrons are made accessible to stromal enzymes, or for cyclic electron flow, as reduced ferredoxin (Fd), or NADPH. We investigated how knockout of an Arabidopsis (Arabidopsis thaliana) ferredoxin:NADPH reductase (FNR) isoprotein and the loss of strong thylakoid binding by the remaining FNR in this mutant affected the channelling of photosynthetic electrons into NADPH- and Fd-dependent metabolism. Chlorophyll fluorescence data show that these mutants have complex variation in cyclic electron flow, dependent on light conditions. Measurements of electron transport in isolated thylakoid and chloroplast systems demonstrated perturbed channelling to NADPH-dependent carbon and Fd-dependent nitrogen assimilating metabolism, with greater competition in the mutant. Moreover, mutants accumulate greater biomass than the wild type under low nitrate growth conditions, indicating that such altered chloroplast electron channelling has profound physiological effects. Taken together, our results demonstrate the integral role played by FNR isoform and location in the partitioning of photosynthetic reducing power.
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Affiliation(s)
- Guy Thomas Hanke
- Laboratory of Regulation of Biological Reactions and Laboratory of Protein Profiling Function Proteomics, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, Japan.
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20
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Hald S, Nandha B, Gallois P, Johnson GN. Feedback regulation of photosynthetic electron transport by NADP(H) redox poise. BIOCHIMICA ET BIOPHYSICA ACTA 2008; 1777:433-40. [PMID: 18371296 DOI: 10.1016/j.bbabio.2008.02.007] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2007] [Revised: 02/27/2008] [Accepted: 02/27/2008] [Indexed: 10/22/2022]
Abstract
When plants experience an imbalance between the absorption of light energy and the use of that energy to drive metabolism, they are liable to suffer from oxidative stress. Such imbalances arise due to environmental conditions (e.g. heat, chilling or drought), and can result in the production of reactive oxygen species (ROS). Here, we present evidence for a novel protective process - feedback redox regulation via the redox poise of the NADP(H) pool. Photosynthetic electron transport was studied in two transgenic tobacco (Nicotiana tabacum) lines - one having reduced levels of ferredoxin NADP+-reductase (FNR), the enzyme responsible for reducing NADP+, and the other reduced levels of glyceraldehyde 3-phosphate dehydrogenase (GAPDH), the principal consumer of NADPH. Both had a similar degree of inhibition of carbon fixation and impaired electron transport. However, whilst FNR antisense plants were obviously stressed, with extensive bleaching of leaves, GAPDH antisense plants showed no visible signs of stress, beyond having a slowed growth rate. Examination of electron transport in these plants indicated that this difference is due to feedback regulation occurring in the GAPDH but not the FNR antisense plants. We propose that this reflects the occurrence of a previously undescribed regulatory pathway responding to the redox poise of the NADP(H) pool.
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Affiliation(s)
- Simon Hald
- Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK
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21
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Velikova V, Loreto F, Brilli F, Stefanov D, Yordanov I. Characterization of juvenile and adult leaves of Eucalyptus globulus showing distinct heteroblastic development: photosynthesis and volatile isoprenoids. PLANT BIOLOGY (STUTTGART, GERMANY) 2008; 10:55-64. [PMID: 18211547 DOI: 10.1055/s-2007-964964] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Heteroblastic Eucalyptus (Eucalyptus globulus L.) leaves were characterized for their functional diversity examining photosynthesis and photosynthesis limitations, transpiration, and the emission of isoprene and monoterpenes. In vivo and combined analyses of gas-exchange, chlorophyll fluorescence, and light absorbance at 830 nm were made on the adaxial and abaxial sides of juvenile and adult leaves. When adult leaves were reversed to illuminate the abaxial side, photosynthesis and isoprene emission were significantly lower than when the adaxial side was illuminated. Monoterpene emission, however, was independent on the side illuminated and similarly partitioned between the two leaf sides. The abaxial side of adult leaves showed less diffusive resistance to CO(2) acquisition by chloroplasts, but also lower ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity, than the adaxial leaf side. In juvenile leaves, photosynthesis, isoprene, and monoterpene emissions were similar when the adaxial or abaxial side was directly illuminated. In the abaxial side of juvenile leaves, photosynthesis did not match the rates attained by the other leaf types when exposed to elevated CO(2), which suggests the occurrence of a limitation of photosynthesis by ribulose bisphosphate (RuBP) regeneration. Accordingly, a reduced efficiency of both photosystems and a high non-radiative dissipation of energy was observed in the abaxial side of juvenile leaves. During light induction, the adaxial side of juvenile leaves also showed a reduced efficiency of photosystem II and a large non-radiative energy dissipation. Our report reveals distinct functional properties in Eucalyptus leaves. Juvenile leaves invest more carbon in isoprene, but not in monoterpenes, and have a lower water use efficiency than adult leaves. Under steady-state conditions, in adult leaves the isobilateral anatomy does not correspond to an equal functionality of the two sides, while in juvenile leaves the dorsiventral anatomy does not result in functional differences in primary or secondary metabolism in the two sides. However, photochemical limitations may reduce the efficiency of carbon fixation in the light, especially in the abaxial side of juvenile leaves.
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Affiliation(s)
- V Velikova
- Institute of Plant Physiology, Bulgarian Academy of Sciences, Acad. G. Bonchev Street, Bl. 21, 1113 Sofia, Bulgaria.
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22
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Govindachary S, Bigras C, Harnois J, Joly D, Carpentier R. Changes in the mode of electron flow to photosystem I following chilling-induced photoinhibition in a C3 plant, Cucumis sativus L. PHOTOSYNTHESIS RESEARCH 2007; 94:333-45. [PMID: 17634753 DOI: 10.1007/s11120-007-9199-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2006] [Accepted: 05/16/2007] [Indexed: 05/09/2023]
Abstract
This study provides evidence for enhanced electron flow from the stromal compartment of the photosynthetic membranes to P700+ via the cytochrome b6/f complex (Cyt b6/f) in leaves of Cucumis sativus L. submitted to chilling-induced photoinhibition. The above is deduced from the P700 oxidation-reduction kinetics studied in the absence of linear electron transport from water to NADP+, cyclic electron transfer mediated through the Q-cycle of Cyt b6/f and charge recombination in photosystem I (PSI). The segregation of these pathways for P700+ rereduction were achieved by the use of a 50-ms multiple turnover white flash or a strong pulse of white or far-red illumination together with inhibitors. In cucumber leaves, chilling-induced photoinhibition resulted in approximately 20% loss of photo-oxidizible P700. The measurement of P700+ was greatly limited by the turnover of cyclic processes in the absence of the linear mode of electron transport as electrons were rapidly transferred to the smaller pool of P700+. The above is explained by integrating the recent model of the cyclic electron flow in C3 plants based on the Cyt b6/f structural data [Joliot and Joliot (2006) Biochim Biophys Acta 1757:362-368] and a photoprotective function elicited by a low NADP+/NAD(P)H ratio [Rajagopal et al. (2003) Biochemistry 42:11839-11845]. Over-reduction of the photosynthetic apparatus results in the accumulation of NAD(P)H in vivo to prevent NADP+-induced reversible conformational changes in PSI and its extensive damage. As the ferredoxin:NADP reductase is fully reduced under these conditions, even in the absence of PSII electron transport, the reduced ferredoxin generated during illumination binds at the stromal openings in the Cyt b6/f complex and activates cyclic electron flow. On the other hand, the excess electrons from the NAD(P)H pool are routed via the Ndh complex in a slow process to maintain moderate reduction of the plastoquinone pool and redox poise required for the operation of ferredoxin:plastoquinone reductase mediated cyclic flow.
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Affiliation(s)
- Sridharan Govindachary
- Groupe de Recherche en Biologie Végétale, Université du Québec à Trois-Rivières, C.P. 500, Trois-Rivières, QC, Canada, G9A 5H7
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Shikanai T. Cyclic electron transport around photosystem I: genetic approaches. ANNUAL REVIEW OF PLANT BIOLOGY 2007; 58:199-217. [PMID: 17201689 DOI: 10.1146/annurev.arplant.58.091406.110525] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The light reactions in photosynthesis convert light energy into chemical energy in the form of ATP and drive the production of NADPH from NADP+. The reactions involve two types of electron flow in the chloroplast. While linear electron transport generates both ATP and NADPH, photosystem I cyclic electron transport is exclusively involved in ATP synthesis. The physiological significance of photosystem I cyclic electron transport has been underestimated, and our knowledge of the machineries involved remains very limited. However, recent genetic approaches using Arabidopsis thaliana have clarified the essential functions of this electron flow in both photoprotection and photosynthesis. Based on several lines of evidence presented here, it is necessary to reconsider the fundamental mechanisms of chloroplast energetics.
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Affiliation(s)
- Toshiharu Shikanai
- Graduate School of Agriculture, Kyushu University, Fukuoka, Japan 812-8581.
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