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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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Ibrahimova U, Zivcak M, Gasparovic K, Rastogi A, Allakhverdiev SI, Yang X, Brestic M. Electron and proton transport in wheat exposed to salt stress: is the increase of the thylakoid membrane proton conductivity responsible for decreasing the photosynthetic activity in sensitive genotypes? PHOTOSYNTHESIS RESEARCH 2021; 150:195-211. [PMID: 34125427 PMCID: PMC8556197 DOI: 10.1007/s11120-021-00853-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 05/28/2021] [Indexed: 05/16/2023]
Abstract
Effects of salinity caused by 150 mM NaCl on primary photochemical reactions and some physiological and biochemical parameters (K+/Na+ ratio, soluble sugars, proline, MDA) have been studied in five Triticum aestivum L. genotypes with contrasting salt tolerance. It was found that 150 mM NaCl significantly decreased the photosynthetic efficiency of two sensitive genotypes. The K+/Na+ ratio decreased in all genotypes exposed to salinity stress when compared with the control. Salinity stress also caused lipid peroxidation and accumulation of soluble sugars and proline. The amounts of soluble sugars and proline were higher in tolerant genotypes than sensitive ones, and lipid peroxidation was higher in sensitive genotypes. The noninvasive measurements of photosynthesis-related parameters indicated the genotype-dependent effects of salinity stress on the photosynthetic apparatus. The significant decrease of chlorophyll content (SPAD values) or adverse effects on photosynthetic functions at the PSII level (measured by the chlorophyll fluorescence parameters) were observed in the two sensitive genotypes only. Although the information obtained by different fast noninvasive techniques were consistent, the correlation analyses identified the highest correlation of the noninvasive records with MDA, K+/Na+ ratio, and free proline content. The lower correlation levels were found for chlorophyll content (SPAD) and Fv/Fm values derived from chlorophyll fluorescence. Performance index (PIabs) derived from fast fluorescence kinetics, and F735/F685 ratio correlated well with MDA and Na+ content. The most promising were the results of linear electron flow measured by MultispeQ sensor, in which we found a highly significant correlation with all parameters assessed. Moreover, the noninvasive simultaneous measurements of chlorophyll fluorescence and electrochromic band shift using this sensor indicated the apparent proton leakage at the thylakoid membranes resulting in a high proton conductivity (gH+), present in sensitive genotypes only. The possible consequences for the photosynthetic functions and the photoprotection are discussed.
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Affiliation(s)
- Ulkar Ibrahimova
- Institute of Molecular Biology and Biotechnologies, Azerbaijan National Academy of Sciences, 11 Izzat Nabiyev, Baku, AZ, 1073, Azerbaijan
- Research Institute of Crop Husbandry, Ministry of Agriculture of the Azerbaijan Republic, Baku, Azerbaijan
| | - Marek Zivcak
- Department of Plant Physiology, Slovak University of Agriculture, Nitra, Slovakia
| | - Kristina Gasparovic
- Department of Plant Physiology, Slovak University of Agriculture, Nitra, Slovakia
| | - Anshu Rastogi
- Laboratory of Bioclimatology, Department of Ecology and Environmental Protection, Poznan University of Life Sciences, Piątkowska 94, 60-649, Poznan, Poland.
- Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente, 7500 AE, Enschede, The Netherlands.
| | - Suleyman I Allakhverdiev
- Institute of Molecular Biology and Biotechnologies, Azerbaijan National Academy of Sciences, 11 Izzat Nabiyev, Baku, AZ, 1073, Azerbaijan
- K.A. Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya Street 35, Moscow, 127276, Russia
- Institute of Basic Biological Problems, Russian Academy of Sciences, Pushchino, Moscow, 142290, Russia
| | - Xinghong Yang
- College of Life Science, State Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop Biology, Shandong Agricultural University, Taian, People's Republic of China
| | - Marian Brestic
- Department of Plant Physiology, Slovak University of Agriculture, Nitra, Slovakia.
- Department of Botany and Plant Physiology, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences, Prague, Czech Republic.
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Chovancek E, Zivcak M, Brestic M, Hussain S, Allakhverdiev SI. The different patterns of post-heat stress responses in wheat genotypes: the role of the transthylakoid proton gradient in efficient recovery of leaf photosynthetic capacity. PHOTOSYNTHESIS RESEARCH 2021; 150:179-193. [PMID: 33393064 DOI: 10.1007/s11120-020-00812-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 12/08/2020] [Indexed: 05/28/2023]
Abstract
The frequency and severity of heat waves are expected to increase in the near future, with a significant impact on physiological functions and yield of crop plants. In this study, we assessed the residual post-heat stress effects on photosynthetic responses of six diverse winter wheat (Triticum sp.) genotypes, differing in country of origin, taxonomy and ploidy (tetraploids vs. hexaploids). After 5 days of elevated temperatures (up to 38 °C), the photosynthetic parameters recorded on the first day of recovery (R1) as well as after the next 4-5 days of the recovery (R2) were compared to those of the control plants (C) grown under moderate temperatures. Based on the values of CO2 assimilation rate (A) and the maximum rates of carboxylation (VCmax) in R1, we identified that the hexaploid (HEX) and tetraploid (TET) species clearly differed in the strength of their response to heat stress. Next, the analyses of gas exchange, simultaneous measurements of PSI and PSII photochemistry and the measurements of electrochromic bandshift (ECS) have consistently shown that photosynthetic and photoprotective functions in leaves of TET genotypes were almost fully recovered in R2, whereas the recovery of photosynthetic and photoprotective functions in the HEX group in R2 was still rather low. A poor recovery was associated with an overly reduced acceptor side of photosystem I as well as high values of the electric membrane potential (Δψ component of the proton motive force, pmf) in the chloroplast. On the other hand, a good recovery of photosynthetic capacity and photoprotective functions was clearly associated with an enhanced ΔpH component of the pmf, thus demonstrating a key role of efficient regulation of proton transport to ensure buildup of the transthylakoid proton gradient needed for photosynthesis restoration after high-temperature episodes.
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Affiliation(s)
- Erik Chovancek
- Department of Plant Physiology, Slovak University of Agriculture, Nitra, Slovak Republic
| | - Marek Zivcak
- Department of Plant Physiology, Slovak University of Agriculture, Nitra, Slovak Republic.
| | - Marian Brestic
- Department of Plant Physiology, Slovak University of Agriculture, Nitra, Slovak Republic
| | - Sajad Hussain
- College of Agronomy, Sichuan Agricultural University, Chengdu, People's Republic of China
- Sichuan Engineering Research Center for Crop Strip Intercropping System, Key Laboratory of Crop Ecophysiology and Farming System in Southwest China, Sichuan Agricultural University, Chengdu, People's Republic of China
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Photosynthetic regulation under fluctuating light at chilling temperature in evergreen and deciduous tree species. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2021; 219:112203. [PMID: 33957467 DOI: 10.1016/j.jphotobiol.2021.112203] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 04/19/2021] [Accepted: 04/25/2021] [Indexed: 11/20/2022]
Abstract
Plants usually experience fluctuating light conditions at chilling temperatures during the autumn season. We hypothesized that photosystem I (PSI) and PSII are more susceptible to photoinhibition under fluctuating light at chilling temperatures in deciduous species relative to evergreen species. We measured the photosynthetic performances under fluctuating light at 6 °C in two evergreen and two deciduous broadleaf tree species. Within the first 10 s after light increased at 6 °C, none of these species could generate an enough trans-thylakoid proton gradient. Meanwhile, PSI was highly oxidised in evergreen species but was highly reduced in deciduous species. This transient over-reduction of PSI in deciduous species was mainly caused by the higher electron flow from PSII. Furthermore, the deciduous species showed a significantly smaller violaxanthin pool and lower non-photochemical quenching under high light conditions at 6 °C, leading to more excess light energy could not be dissipated in PSII. Hence, we propose that fluctuating light combined with chilling temperature cause the over-reduction of photosynthetic electron chain in deciduous species.
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Su L, Xie J, Wen W, Li J, Zhou P, An Y. Interaction of zinc and IAA alleviate aluminum-induced damage on photosystems via promoting proton motive force and reducing proton gradient in alfalfa. BMC PLANT BIOLOGY 2020; 20:433. [PMID: 32948141 PMCID: PMC7501636 DOI: 10.1186/s12870-020-02643-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/01/2020] [Accepted: 09/09/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND In acidic soils, aluminum (Al) competing with Zn results in Zn deficiency in plants. Zn is essential for auxin biosynthesis. Zn-mediated alleviation of Al toxicity has been rarely studied, the mechanism of Zn alleviation on Al-induced photoinhibition in photosystems remains unclear. The objective of this study was to investigate the effects of Zn and IAA on photosystems of Al-stressed alfalfa. Alfalfa seedlings with or without apical buds were exposed to 0 or100 μM AlCl3 combined with 0 or 50 μM ZnCl2, and then foliar spray with water or 6 mg L- 1 IAA. RESULTS Our results showed that Al stress significantly decreased plant growth rate, net photosynthetic rate (Pn), quantum yields and electron transfer rates of PSI and PSII. Exogenous application of Zn and IAA significantly alleviated the Al-induced negative effects on photosynthetic machinery, and an interaction of Zn and IAA played an important role in the alleviative effects. After removing apical buds of Al-stressed alfalfa seedlings, the values of pmf, gH+ and Y(II) under exogenous spraying IAA were significantly higher, and ΔpHpmf was significantly lower in Zn addition than Al treatment alone, but the changes did not occur under none spraying IAA. The interaction of Zn and IAA directly increased Y(I), Y(II), ETRI and ETRII, and decreased O2- content of Al-stressed seedlings. In addition, the transcriptome analysis showed that fourteen functionally noted genes classified into functional category of energy production and conversion were differentially expressed in leaves of alfalfa seedlings with and without apical buds. CONCLUSION Our results suggest that the interaction of zinc and IAA alleviate aluminum-induced damage on photosystems via increasing pmf and decreasing ΔpHpmf between lumen and stroma.
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Affiliation(s)
- Liantai Su
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
| | - Jianping Xie
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
| | - Wuwu Wen
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
| | - Jiaojiao Li
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
| | - Peng Zhou
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
| | - Yuan An
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China.
- Key Laboratory of Urban Agriculture, Ministry of Agriculture, Shanghai, 201101, China.
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Tan SL, Yang YJ, Huang W. Moderate heat stress accelerates photoinhibition of photosystem I under fluctuating light in tobacco young leaves. PHOTOSYNTHESIS RESEARCH 2020; 144:373-382. [PMID: 32333230 DOI: 10.1007/s11120-020-00754-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 04/19/2020] [Indexed: 06/11/2023]
Abstract
Moderate heat stress and fluctuating light are typical conditions in summer in tropical and subtropical regions. This type of stress can cause photodamage to photosystems I and II (PSI and PSII). However, photosynthetic responses to the combination of heat and fluctuating light in young leaves are little known. In this study, we investigated chlorophyll fluorescence and P700 redox state under fluctuating light at 25 °C and 42 °C in young leaves of tobacco. Our results indicated that fluctuating light caused selective photodamage to PSI in the young leaves at 25 °C and 42 °C. Furthermore, the moderate heat stress significantly accelerated photoinhibition of PSI under fluctuating light. Within the first 10 s after transition from low to high light, cyclic electron flow (CEF) around PSI was highly stimulated at 25 °C but was slightly activated at 42 °C. Such depression of CEF activation at moderate heat stress were unable to maintain energy balance under high light. As a result, electron flow from PSI to NADP+ was restricted, leading to the over-reduction of PSI electron carriers. These results indicated that moderate heat stress altered the CEF performance under fluctuating light and thus accelerated PSI photoinhibition in tobacco young leaves.
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Affiliation(s)
- Shun-Ling Tan
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ying-Jie Yang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Wei Huang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China.
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Sun H, Yang YJ, Huang W. The water-water cycle is more effective in regulating redox state of photosystem I under fluctuating light than cyclic electron transport. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1861:148235. [PMID: 32485160 DOI: 10.1016/j.bbabio.2020.148235] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 05/12/2020] [Accepted: 05/26/2020] [Indexed: 11/28/2022]
Abstract
Photosynthetic electron flux from water via photosystem II (PSII) and PSI to oxygen (water-water cycle) may act as an alternative electron sink under fluctuating light in angiosperms. We measured the P700 redox kinetics and electrochromic shift signal under fluctuating light in 11 Camellia species and tobacco leaves. Upon dark-to-light transition, these Camellia species showed rapid re-oxidation of P700. However, this rapid re-oxidation of P700 was not observed when measured under anaerobic conditions, as was in experiment with tobacco performed under aerobic conditions. Therefore, photo-reduction of O2 mediated by water-water cycle was functional in these Camellia species but not in tobacco. Within the first 10 s after transition from low to high light, PSI was highly oxidized in these Camellia species but was over-reduced in tobacco leaves. Furthermore, such rapid oxidation of PSI in these Camellia species was independent of the formation of trans-thylakoid proton gradient (ΔpH). These results indicated that in addition to ΔpH-dependent photosynthetic control, the water-water cycle can protect PSI against photoinhibition under fluctuating light in these Camellia species. We here propose that the water-water cycle is an overlooked strategy for photosynthetic regulation under fluctuating light in angiosperms.
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Affiliation(s)
- Hu Sun
- Key Laboratory of Economic Plants and Biotechnology, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ying-Jie Yang
- Key Laboratory of Economic Plants and Biotechnology, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wei Huang
- Key Laboratory of Economic Plants and Biotechnology, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, China.
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Yang YJ, Zhang SB, Wang JH, Huang W. The decline in photosynthetic rate upon transfer from high to low light is linked to the slow kinetics of chloroplast ATP synthase in Bletilla striata. PHOTOSYNTHESIS RESEARCH 2020; 144:13-21. [PMID: 32166520 DOI: 10.1007/s11120-020-00725-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 02/12/2020] [Indexed: 06/10/2023]
Abstract
Upon a sudden transition from high to low light, the rate of CO2 assimilation (AN) in some plants first decreases to a low level before gradually becoming stable. However, the underlying mechanisms remain controversial. The activity of chloroplast ATP synthase (gH+) is usually depressed under high light when compared with low light. Therefore, we hypothesize that upon a sudden transfer from high to low light, the relatively low gH+ restricts ATP synthesis and thus causes a reduction in AN. To test this hypothesis, we measured gas exchange, chlorophyll fluorescence, P700 redox state, and electrochromic shift signals in Bletilla striata (Orchidaceae). After the transition from saturating to lower irradiance, AN and ETRII decreased first to a low level and then gradually increased to a stable value. Within the first seconds after transfer from high to low light, gH+ was maintained at low levels. During further exposure to low light, gH+ gradually increased to a stable value. Interestingly, a tight positive relationship was found between gH+ and ETRII. These results suggested that upon a sudden transition from high to low light, AN was restricted by gH+ at the step of ATP synthesis. Taken together, we propose that the decline in AN upon sudden transfer from high to low light is linked to the slow kinetics of chloroplast ATP synthase.
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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
| | - Shi-Bao Zhang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China
| | - Ji-Hua Wang
- Yunnan Academy of Agricultural Sciences, Kunming, 650205, Yunnan, China.
| | - Wei Huang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China.
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Photosynthetic Response Mechanism of Soil Salinity-Induced Cross-Tolerance to Subsequent Drought Stress in Tomato Plants. PLANTS 2020; 9:plants9030363. [PMID: 32187994 PMCID: PMC7154942 DOI: 10.3390/plants9030363] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 02/28/2020] [Accepted: 03/12/2020] [Indexed: 02/06/2023]
Abstract
Soil salinization and water shortage cause ion imbalance and hyperosmoticity in plant cells, adversely impairing photosynthesis efficiency. How soil salinity-induced photosynthetic acclimation influences the cross-tolerance to drought conditions represents a promising research topic. This study was to reveal the photosynthetic mechanism of soil salinity-induced resistance to the subsequent drought stress in tomato leaves through comprehensive photosynthesis-related spectroscopy analysis. We conducted soil salinity pretreatment and subsequent drought stress experiments, including irrigation with 100 mL water, 100 mL 100 mM NaCl solution (NaCl100), 50 mL water, and 50 mL 100 mM NaCl solution (NaCl50) for five days, followed by five-day drought stress. The results showed that soil salinity treatment by NaCl decreased the rate of photosynthetic gas exchange but enhanced CO2 assimilation, along with photosystem II [PS(II)] and photosystem I [PS(I)] activity and photochemical efficiency in tomato plants compared with water pretreatment after subsequent drought stress. NaCl100 and NaCl50 had the capacity to maintain non-photochemical quenching (NPQ) of chlorophyll fluorescence and the cyclic electron (CEF) flow around PSI in tomato leaves after being subjected to subsequent drought stress, thus avoiding the decrease of photosynthetic efficiency under drought conditions. NaCl100 and NaCl50 pretreatment induced a higher proton motive force (pmf) and also alleviated the damage to the thylakoid membrane and adenosine triphosphate (ATP) synthase of tomato leaves caused by subsequent drought stress. Overall, soil salinity treatment could enhance drought resistance in tomato plants by inducing NPQ, maintaining CEF and pmf that tradeoff between photoprotection and photochemistry reactions. This study also provides a photosynthetic perspective for salt and drought cross-tolerance.
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Tan SL, Yang YJ, Liu T, Zhang SB, Huang W. Responses of photosystem I compared with photosystem II to combination of heat stress and fluctuating light in tobacco leaves. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2020; 292:110371. [PMID: 32005377 DOI: 10.1016/j.plantsci.2019.110371] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 12/02/2019] [Accepted: 12/07/2019] [Indexed: 05/02/2023]
Abstract
Moderate heat stress is usually accompanied with fluctuating light in summer. Although either heat stress or fluctuating light can cause photoinhibition of photosystems I and II (PSI and PSII), it is unclear whether moderate heat stress accelerate photoinhibition under fluctuating light. Here, we measured chlorophyll fluorescence, P700 redox state and the electrochromic shift signal under fluctuating light at 25 °C and 42 °C for tobacco leaves. We found that (1) the thylakoid proton conductance was significantly enhanced at 42 °C, leading to a decline in trans-thylakoid proton gradient (ΔpH); (2) this low ΔpH at 42 °C did not decrease donor-side limitation of PSI and thermal energy dissipation in PSII; (3) the activation of cyclic electron flow (CEF) around PSI was elevated at 42 °C; and (4) the moderate heat stress did not accelerate photoinhibition of PSI and PSII under fluctuating light. These results strongly indicate that under moderate heat stress the stimulation of CEF protects PSI under fluctuating light in tobacco leaves.
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Affiliation(s)
- Shun-Ling Tan
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ying-Jie Yang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Tao Liu
- National Local Joint Engineering Research Center on Germplasm Utilization and Innovation of Chinese Medicinal Materials in Southwest China, Yunnan Agricultural University, Kunming, 650201, 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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11
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Sun H, Zhang SB, Liu T, Huang W. Decreased photosystem II activity facilitates acclimation to fluctuating light in the understory plant Paris polyphylla. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2019; 1861:148135. [PMID: 31821793 DOI: 10.1016/j.bbabio.2019.148135] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2019] [Revised: 11/22/2019] [Accepted: 12/04/2019] [Indexed: 01/11/2023]
Abstract
In forests, understory plants are usually exposed to sunflecks on timescales of seconds or minutes. However, it is unclear how understory plants acclimate to fluctuating light. In this study, we compared chlorophyll fluorescence, PSI redox state and the electrochromic shift signal under fluctuating light between an understory plant Paris polyphylla (Liliaceae) and a light-demanding plant Bletilla striata (Orchidaceae). Within the first seconds after transition from low to high light, PSI was highly oxidized in P. polyphylla but was highly reduced in B. striata, although both species could not generate a sufficient trans-thylakoid proton gradient (ΔpH). Furthermore, the outflow of electrons from PSI to O2 was not significant in P. polyphylla, as indicated by the P700 redox kinetics upon dark-to-light transition. Therefore, the different responses of PSI to fluctuating light between P. polyphylla and B. striata could not be explained by ΔpH formation or alternative electron transport. In contrast, upon a sudden transition from low to high light, electron flow from PSII was much lower in P. polyphylla than in B. striata, suggesting that the rapid oxidation of PSI in P. polyphylla was largely attributed to the lower PSII activity. We propose, for the first time, that down-regulation of PSII activity is an important strategy used by some understory angiosperms to cope with sunflecks.
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Affiliation(s)
- Hu Sun
- Kunming Institute of Botany, Chinese Academy of Sciences, 650201 Kunming, China; University of Chinese Academy of Sciences, 100049 Beijing, China
| | - Shi-Bao Zhang
- Kunming Institute of Botany, Chinese Academy of Sciences, 650201 Kunming, China
| | - Tao Liu
- National Local Joint Engineering Research Center on Germplasm Utilization and Innovation of Chinese Medicinal Materials in Southwest China, Yunnan Agricultural University, 650201 Kunming, China.
| | - Wei Huang
- Kunming Institute of Botany, Chinese Academy of Sciences, 650201 Kunming, China.
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12
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Huang W, Yang YJ, Wang JH, Hu H. Photorespiration is the major alternative electron sink under high light in alpine evergreen sclerophyllous Rhododendron species. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2019; 289:110275. [PMID: 31623777 DOI: 10.1016/j.plantsci.2019.110275] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 08/08/2019] [Accepted: 09/13/2019] [Indexed: 06/10/2023]
Abstract
Owing to the high leaf mass per area, alpine evergreen sclerophyllous Rhododendron have low values of mesophyll conductance (gm). The resulting low chloroplast CO2 concentration aggravates photorespiration, which requires a higher ATP/NADPH ratio. However, the significance of photorespiration and underlying mechanisms of energy balance in these species are little known. In this study, eight alpine evergreen sclerophyllous Rhododendron species grown in a common garden were tested for their gm, electron flow to photorespiration, and energy balancing. Under saturating light, gm was the most limiting factor for net photosynthesis (AN) in all species, and the species differences in AN were primarily driven by gm rather than stomatal conductance. The total electron flow through photosystem II (ETRII) nearly equaled the electron transport required for Rubisco carboxylation and oxygenation. Furthermore, blocking electron flow to photosystem I with appropriate inhibitors showed that electron flow to plastic terminal oxidase was not observed. As a result, these studied species showed little alternative electron flow mediated by water-water cycle or plastic terminal oxidase. By comparison, the ratio of electron transport consumed by photorespiration to ETRII (JPR/ETRII), ranging from 43%∼55%, was negatively correlated to AN and gm. Furthermore, the increased ATP production required by enhanced photorespiration was regulated by cyclic electron flow around photosystem I. These results indicate that photorespiration is the major electron sink for dissipation of excess excitation energy in the alpine evergreen sclerophyllous Rhododendron species. The coordination of gm, photorespiration and cyclic electron flow is important for sustaining leaf photosynthesis.
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Affiliation(s)
- Wei Huang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, 650201, PR China
| | - Ying-Jie Yang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, 650201, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Ji-Hua Wang
- Flower Research Institute of Yunnan Academy of Agricultural Sciences, Kunming, Yunnan, PR China.
| | - Hong Hu
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, 650201, PR China.
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Yang YJ, Ding XX, Huang W. Stimulation of cyclic electron flow around photosystem I upon a sudden transition from low to high light in two angiosperms Arabidopsis thaliana and Bletilla striata. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2019; 287:110166. [PMID: 31481226 DOI: 10.1016/j.plantsci.2019.110166] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 05/20/2019] [Accepted: 06/06/2019] [Indexed: 06/10/2023]
Abstract
In angiosperms, cyclic electron flow (CEF) around photosystem I (PSI) is more important for photoprotection under fluctuating light than under constant light. However, the underlying mechanism is not well known. In the present study, we measured the CEF activity, P700 redox state and electrochromic shift signal upon a sudden transition from low to high light in wild-type plants of Arabidopsis thaliana and Bletilla striata (Orchidaceae). Within the first 20 s after transition from low to high light, P700 was highly reduced in both species, which was accompanied with a sufficient proton gradient (ΔpH) across the thylakoid membranes. Meanwhile, the level of CEF activation was elevated. After transition from low to high light for 60 s, the plants generated an optimal ΔpH. Under such condition, PSI was highly oxidized and the level of CEF activation decreased to the steady state. Furthermore, the CEF activation was positively correlated to the P700 reduction ratio. These results indicated that upon a sudden transition from low to high light, the insufficient ΔpH led to the over-reduction of PSI electron carriers, which in turn stimulated the CEF around PSI. This transient stimulation of CEF not only favored the rapid ΔpH formation but also accepted electrons from PSI, thus protecting PSI at donor and acceptor sides. These findings provide new insights into the important role of CEF in regulation of photosynthesis under fluctuating light.
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Affiliation(s)
- Ying-Jie Yang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, 650201, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiao-Xi Ding
- Kunming Forest Resources Administration, Kunming, China
| | - Wei Huang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, 650201, China.
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Yang YJ, Zhang SB, Wang JH, Huang W. Photosynthetic regulation under fluctuating light in field-grown Cerasus cerasoides: A comparison of young and mature leaves. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2019; 1860:148073. [PMID: 31473302 DOI: 10.1016/j.bbabio.2019.148073] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 08/22/2019] [Accepted: 08/27/2019] [Indexed: 11/15/2022]
Abstract
Photosystem I (PSI) is a potential target of photoinhibition under fluctuating light. However, photosynthetic regulation under fluctuating light in field-grown plants is little known. Furthermore, it is unclear how young leaves protect PSI against fluctuating light under natural field conditions. In the present study, we examined chlorophyll fluorescence, P700 redox state and the electrochromic shift signal in the young and mature leaves of field-grown Cerasus cerasoides (Rosaceae). Within the first seconds after any increase in light intensity, young leaves showed higher proton gradient (ΔpH) across the thylakoid membranes than the mature leaves, preventing over-reduction of PSI in the young leaves. As a result, PSI was more tolerant to fluctuating light in the young leaves than in the mature leaves. Interestingly, after transition from low to high light, the activity of cyclic electron flow (CEF) in young leaves increased first to a high level and then decreased to a stable value, while this rapid stimulation of CEF was not observed in the mature leaves. Furthermore, the over-reduction of PSI significantly stimulated CEF in the young leaves but not in the mature leaves. Taken together, within the first seconds after any increase in illumination, the stimulation of CEF favors the rapid lumen acidification and optimizes the PSI redox state in the young leaves, protecting PSI against photoinhibition under fluctuating light in field-grown plants.
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Affiliation(s)
- Ying-Jie Yang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shi-Bao Zhang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, China
| | - Ji-Hua Wang
- Flower Research Institute of Yunnan Academy of Agricultural Sciences, Kunming, Yunnan, China.
| | - Wei Huang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, China.
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15
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Yang YJ, Zhang SB, Huang W. Photosynthetic regulation under fluctuating light in young and mature leaves of the CAM plant Bryophyllum pinnatum. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2019; 1860:469-477. [PMID: 31029592 DOI: 10.1016/j.bbabio.2019.04.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 12/20/2018] [Accepted: 01/06/2019] [Indexed: 11/27/2022]
Abstract
Photosystem I (PSI) is the potential target of photodamage under fluctuating light in angiosperms. However, the response of PSI to fluctuating light in young leaves has not yet been clarified. Furthermore, the photosynthetic regulation under fluctuating light in crassulacean acid metabolism (CAM) plants is little known. In this study, we measured PSI redox state and the electrochromic shift signal in the mature and young leaves of a CAM species Bryophyllum pinnatum. The mature leaves showed stronger capacity for photo-reduction of O2 mediated by the alternative electron flow (probably the water-water cycle) when compared with the young leaves. After an increase in light intensity, both the mature and young leaves showed insufficient proton gradient (ΔpH) across the thylakoid membranes within the first seconds. Meanwhile, PSI was highly oxidized in the mature leaves but was in a more reduced state in the young leaves. Furthermore, young leaves were more susceptible to PSI photoinhibition under fluctuating light. Therefore, in the mature leaves, the alternative electron flow significantly optimized the PSI redox state under fluctuating light at relatively low ΔpH. By comparison, in the young leaves, PSI redox state was largely determined by the buildup of ΔpH. Therefore, the major photoprotective mechanism responsible for safeguarding PSI under fluctuating light can be influenced by leaf developmental stages.
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Affiliation(s)
- Ying-Jie Yang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Shi-Bao Zhang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, PR China.
| | - Wei Huang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, PR China.
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Huang W, Yang YJ, Zhang SB. The role of water-water cycle in regulating the redox state of photosystem I under fluctuating light. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2019; 1860:383-390. [PMID: 30890407 DOI: 10.1016/j.bbabio.2019.03.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 12/18/2018] [Accepted: 03/14/2019] [Indexed: 10/27/2022]
Abstract
The regulation of photosystem I (PSI) redox state under fluctuating light was investigated for four species using P700 measurement and electrochromic shift analysis. Species included the angiosperms Camellia japonica, Bletilla striata and Arabidopsis thaliana and the fern Cyrtomium fortunei. For the first seconds after transition from low to high light, all species showed relatively low levels of the proton gradient (ΔpH) across the thylakoid membranes. At this moment, PSI was highly oxidized in C. japonica and C. fortunei but was over-reduced in B. striata and A. thaliana. In B. striata and A. thaliana, the redox state of PSI was largely dependent on ΔpH. In contrast, the rapid oxidation of P700 in C. japonica was relatively independent of ΔpH, but was mainly dependent on the outflow of electrons to O2 via the water-water cycle. In the fern C. fortunei, PSI redox state was rapidly regulated by the fast photo-reduction of O2 rather than the ΔpH. These results indicate that mechanisms regulating PSI redox state under fluctuating light differ greatly between species. We propose that the water-water cycle is an important mechanism regulating the PSI redox state in angiosperms.
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Affiliation(s)
- Wei Huang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, China
| | - Ying-Jie Yang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shi-Bao Zhang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, China.
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