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Colpo A, Demaria S, Boldrini P, Baldisserotto C, Pancaldi S, Ferroni L. Ultrastructural organization of the thylakoid system during the afternoon relocation of the giant chloroplast in Selaginella martensii Spring (Lycopodiophyta). PROTOPLASMA 2024; 261:143-159. [PMID: 37612526 PMCID: PMC10784399 DOI: 10.1007/s00709-023-01888-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 07/30/2023] [Indexed: 08/25/2023]
Abstract
Within the ancient vascular plant lineage known as lycophytes, many Selaginella species contain only one giant chloroplast in the upper epidermal cells of the leaf. In deep-shade species, such as S. martensii, the chloroplast is cup-shaped and the thylakoid system differentiates into an upper lamellar region and a lower granal region (bizonoplast). In this report, we describe the ultrastructural changes occurring in the giant chloroplast hosted in the epidermal cells of S. martensii during the daily relocation of the organelle. The process occurs in up to ca. 40% of the microphylls without the plants being exposed to high-light flecks. The relocated chloroplast loses its cup shape: first, it flattens laterally toward the radial cell wall and then assumes a more globular shape. The loss of the conical cell shape, the side-by-side lateral positioning of vacuole and chloroplast, and the extensive rearrangement of the thylakoid system to only granal cooperate in limiting light absorption. While the cup-shaped chloroplast emphasizes the light-harvesting capacity in the morning, the relocated chloroplast is suggested to support the renewal of the thylakoid system during the afternoon, including the recovery of photosystem II (PSII) from photoinhibition. The giant chloroplast repositioning is part of a complex reversible reshaping of the whole epidermal cell.
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Affiliation(s)
- Andrea Colpo
- Department of Environmental and Prevention Sciences, University of Ferrara, Corso Ercole I d'Este 32, 44121, Ferrara, Italy
| | - Sara Demaria
- Department of Environmental and Prevention Sciences, University of Ferrara, Corso Ercole I d'Este 32, 44121, Ferrara, Italy
| | - Paola Boldrini
- Center of Electron Microscopy, University of Ferrara, Via Luigi Borsari 46, 44121, Ferrara, Italy
| | - Costanza Baldisserotto
- Department of Environmental and Prevention Sciences, University of Ferrara, Corso Ercole I d'Este 32, 44121, Ferrara, Italy
| | - Simonetta Pancaldi
- Department of Environmental and Prevention Sciences, University of Ferrara, Corso Ercole I d'Este 32, 44121, Ferrara, Italy.
| | - Lorenzo Ferroni
- Department of Environmental and Prevention Sciences, University of Ferrara, Corso Ercole I d'Este 32, 44121, Ferrara, Italy.
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Luo D, Huang G, Zhang Q, Zhou G, Peng S, Li Y. Plasticity of mesophyll cell density and cell wall thickness and composition play a pivotal role in regulating plant growth and photosynthesis under shading in rapeseed. ANNALS OF BOTANY 2023; 132:963-978. [PMID: 37739395 PMCID: PMC10808032 DOI: 10.1093/aob/mcad140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 09/20/2023] [Indexed: 09/24/2023]
Abstract
BACKGROUND AND AIMS Plasticity of leaf growth and photosynthesis is an important strategy of plants to adapt to shading stress; however, their strategy of leaf development to achieve a simultaneous increase in leaf area and photosynthesis under shading remains unknown. METHODS In the present study, a pot experiment was conducted using three rapeseed genotypes of Huayouza 50 (HYZ50), Zhongshuang 11 (ZS11) and Huayouza 62 (HYZ62), and the responses of plant growth, leaf morphoanatomical traits, cell wall composition and photosynthesis to shading were investigated. KEY RESULTS Shading significantly increased leaf area per plant (LAplant) in all genotypes, but the increase in HYZ62 was greater than that in HYZ50 and ZS11. The greater increment of LAplant in HYZ62 was related to the larger decrease in leaf mass per area (LMA) and leaf density (LD), which were in turn related to less densely packed mesophyll cells and thinner cell walls (Tcw). Moreover, shading significantly increased photosynthesis in HYZ62 but significantly decreased it in HYZ50. The enhanced photosynthesis in HYZ62 was related to increased mesophyll conductance (gm) due primarily to thinner cell walls. CONCLUSIONS The data presented indicate that the different plasticity of mesophyll cell density, cell wall thickness and cell wall composition in response to shading can dramatically affect leaf growth and photosynthesis.
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Affiliation(s)
- Dongxu Luo
- Ministry of Agriculture Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Guanjun Huang
- Ministry of Agriculture Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Qiangqiang Zhang
- Rice Ecophysiology and Precise Management Laboratory, College of Agronomy, Anhui Agricultural University, Anhui 230036, China
| | - Guangsheng Zhou
- Ministry of Agriculture Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Shaobing Peng
- Ministry of Agriculture Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Yong Li
- Ministry of Agriculture Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
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Wang XQ, Sun H, Zeng ZL, Huang W. Within-branch photosynthetic gradients are more related to the coordinated investments of nitrogen and water than leaf mass per area. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2023; 198:107681. [PMID: 37054614 DOI: 10.1016/j.plaphy.2023.107681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 03/18/2023] [Accepted: 04/03/2023] [Indexed: 05/07/2023]
Abstract
Nitrogen (N) and water are key resources for leaf photosynthesis and the growth of whole plants. Within-branch leaves need different amounts of N and water to support their differing photosynthetic capacities according to light exposure. To test this scheme, we measured the within-branch investments of N and water and their effects on photosynthetic traits in two deciduous tree species Paulownia tomentosa and Broussonetia papyrifera. We found that leaf photosynthetic capacity gradually increased from branch bottom to top (i.e. from shade to sun leaves). Concomitantly, stomatal conductance (gs) and leaf N content gradually increased, owing to the symport of water and inorganic mineral from root to leaf. Variation of leaf N content led to large gradients of mesophyll conductance, maximum velocity of Rubisco for carboxylation, maximum electron transport rate and leaf mass per area (LMA). Correlation analysis indicated that the within-branch difference in photosynthetic capacity was mainly related to gs and leaf N content, with a relatively minor contribution of LMA. Furthermore, the simultaneous increases of gs and leaf N content enhanced photosynthetic N use efficiency (PNUE) but hardly affected water use efficiency. Therefore, within-branch adjustment of N and water investments is an important strategy used by plants to optimize the overall photosynthetic carbon gain and PNUE.
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Affiliation(s)
- Xiao-Qian Wang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China
| | - Hu Sun
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhi-Lan Zeng
- 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, Wang XQ, Zeng ZL, Yang YJ, Huang W. Exogenous melatonin strongly affects dynamic photosynthesis and enhances water-water cycle in tobacco. FRONTIERS IN PLANT SCIENCE 2022; 13:917784. [PMID: 35991431 PMCID: PMC9381976 DOI: 10.3389/fpls.2022.917784] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 07/11/2022] [Indexed: 06/09/2023]
Abstract
Melatonin (MT), an important phytohormone synthesized naturally, was recently used to improve plant resistance against abiotic and biotic stresses. However, the effects of exogenous melatonin on photosynthetic performances have not yet been well clarified. We found that spraying of exogenous melatonin (100 μM) to leaves slightly affected the steady state values of CO2 assimilation rate (A N ), stomatal conductance (g s ) and mesophyll conductance (g m ) under high light in tobacco leaves. However, this exogenous melatonin strongly delayed the induction kinetics of g s and g m , leading to the slower induction speed of A N . During photosynthetic induction, A N is mainly limited by biochemistry in the absence of exogenous melatonin, but by CO2 diffusion conductance in the presence of exogenous melatonin. Therefore, exogenous melatonin can aggravate photosynthetic carbon loss during photosynthetic induction and should be used with care for crop plants grown under natural fluctuating light. Within the first 10 min after transition from low to high light, photosynthetic electron transport rates (ETR) for A N and photorespiration were suppressed in the presence of exogenous melatonin. Meanwhile, an important alternative electron sink, namely water-water cycle, was enhanced to dissipate excess light energy. These results indicate that exogenous melatonin upregulates water-water cycle to facilitate photoprotection. Taking together, this study is the first to demonstrate that exogenous melatonin inhibits dynamic photosynthesis and improves photoprotection in higher plants.
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Affiliation(s)
- Hu Sun
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xiao-Qian Wang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- School of Life Sciences, Northwest University, Xi’an, China
| | - Zhi-Lan Zeng
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Ying-Jie Yang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - Wei Huang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
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Sun H, Zhang YQ, Zhang SB, Huang W. Photosynthetic Induction Under Fluctuating Light Is Affected by Leaf Nitrogen Content in Tomato. FRONTIERS IN PLANT SCIENCE 2022; 13:835571. [PMID: 35251106 PMCID: PMC8891375 DOI: 10.3389/fpls.2022.835571] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 01/17/2022] [Indexed: 06/09/2023]
Abstract
The response of photosynthetic CO2 assimilation to changes of illumination affects plant growth and crop productivity under natural fluctuating light conditions. However, the effects of nitrogen (N) supply on photosynthetic physiology after transition from low to high light are seldom studied. To elucidate this, we measured gas exchange and chlorophyll fluorescence under fluctuating light in tomato (Solanum lycopersicum) seedlings grown with different N conditions. After transition from low to high light, the induction speeds of net CO2 assimilation (A N ), stomatal conductance (g s ), and mesophyll conductance (g m ) delayed with the decline in leaf N content. The time to reach 90% of maximum A N , g s and g m was negatively correlated with leaf N content. This delayed photosynthetic induction in plants grown under low N concentration was mainly caused by the slow induction response of g m rather than that of g s . Furthermore, the photosynthetic induction upon transfer from low to high light was hardly limited by photosynthetic electron flow. These results indicate that decreased leaf N content declines carbon gain under fluctuating light in tomato. Increasing the induction kinetics of g m has the potential to enhance the carbon gain of field crops grown in infertile soil.
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Affiliation(s)
- Hu Sun
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yu-Qi Zhang
- Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agriculture Sciences, Beijing, China
| | - Shi-Bao Zhang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - Wei Huang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
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Yang YJ, Shi Q, Sun H, Mei RQ, Huang W. Differential Response of the Photosynthetic Machinery to Fluctuating Light in Mature and Young Leaves of Dendrobium officinale. FRONTIERS IN PLANT SCIENCE 2022; 12:829783. [PMID: 35185969 PMCID: PMC8850366 DOI: 10.3389/fpls.2021.829783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 12/27/2021] [Indexed: 06/14/2023]
Abstract
A key component of photosynthetic electron transport chain, photosystem I (PSI), is susceptible to the fluctuating light (FL) in angiosperms. Cyclic electron flow (CEF) around PSI and water-water cycle (WWC) are both used by the epiphytic orchid Dendrobium officinale to protect PSI under FL. This study examined whether the ontogenetic stage of leaf has an impact on the photoprotective mechanisms dealing with FL. Thus, chlorophyll fluorescence and P700 signals under FL were measured in D. officinale young and mature leaves. Upon transition from dark to actinic light, a rapid re-oxidation of P700 was observed in mature leaves but disappeared in young leaves, indicating that WWC existed in mature leaves but was lacking in young leaves. After shifting from low to high light, PSI over-reduction was clearly missing in mature leaves. By comparison, young leaves showed a transient PSI over-reduction within the first 30 s, which was accompanied with highly activation of CEF. Therefore, the effect of FL on PSI redox state depends on the leaf ontogenetic stage. In mature leaves, WWC is employed to avoid PSI over-reduction. In young leaves, CEF around PSI is enhanced to compensate for the lack of WWC and thus to prevent an uncontrolled PSI over-reduction induced by FL.
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Affiliation(s)
- Ying-Jie Yang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - Qi Shi
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Hu Sun
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Ren-Qiang Mei
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - Wei Huang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- Bio-Innovation Center of DR PLANT, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
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Shi Q, Sun H, Timm S, Zhang S, Huang W. Photorespiration Alleviates Photoinhibition of Photosystem I under Fluctuating Light in Tomato. PLANTS 2022; 11:plants11020195. [PMID: 35050082 PMCID: PMC8780929 DOI: 10.3390/plants11020195] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Revised: 12/30/2021] [Accepted: 12/31/2021] [Indexed: 12/12/2022]
Abstract
Fluctuating light (FL) is a typical natural light stress that can cause photodamage to photosystem I (PSI). However, the effect of growth light on FL-induced PSI photoinhibition remains controversial. Plants grown under high light enhance photorespiration to sustain photosynthesis, but the contribution of photorespiration to PSI photoprotection under FL is largely unknown. In this study, we examined the photosynthetic performance under FL in tomato (Lycopersicon esculentum) plants grown under high light (HL-plants) and moderate light (ML-plants). After an abrupt increase in illumination, the over-reduction of PSI was lowered in HL-plants, resulting in a lower FL-induced PSI photoinhibition. HL-plants displayed higher capacities for CO2 fixation and photorespiration than ML-plants. Within the first 60 s after transition from low to high light, PSII electron transport was much higher in HL-plants, but the gross CO2 assimilation rate showed no significant difference between them. Therefore, upon a sudden increase in illumination, the difference in PSII electron transport between HL- and ML-plants was not attributed to the Calvin–Benson cycle but was caused by the change in photorespiration. These results indicated that the higher photorespiration in HL-plants enhanced the PSI electron sink downstream under FL, which mitigated the over-reduction of PSI and thus alleviated PSI photoinhibition under FL. Taking together, we here for the first time propose that photorespiration acts as a safety valve for PSI photoprotection under FL.
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Affiliation(s)
- Qi Shi
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; (Q.S.); (H.S.); (S.Z.)
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hu Sun
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; (Q.S.); (H.S.); (S.Z.)
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Stefan Timm
- Plant Physiology Department, University of Rostock, D-18051 Rostock, Germany;
| | - Shibao Zhang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; (Q.S.); (H.S.); (S.Z.)
| | - Wei Huang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; (Q.S.); (H.S.); (S.Z.)
- Correspondence:
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8
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Colpo A, Baldisserotto C, Pancaldi S, Sabia A, Ferroni L. Photosystem II photoinhibition and photoprotection in a lycophyte, Selaginella martensii. PHYSIOLOGIA PLANTARUM 2022; 174:e13604. [PMID: 34811759 PMCID: PMC9300044 DOI: 10.1111/ppl.13604] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 11/09/2021] [Accepted: 11/19/2021] [Indexed: 05/13/2023]
Abstract
The Lycophyte Selaginella martensii efficiently acclimates to diverse light environments, from deep shade to full sunlight. The plant does not modulate the abundance of the Light Harvesting Complex II, mostly found as a free trimer, and does not alter the maximum capacity of thermal dissipation (NPQ). Nevertheless, the photoprotection is expected to be modulatable upon long-term light acclimation to preserve the photosystems (PSII, PSI). The effects of long-term light acclimation on PSII photoprotection were investigated using the chlorophyll fluorometric method known as "photochemical quenching measured in the dark" (qPd ). Singularly high-qPd values at relatively low irradiance suggest a heterogeneous antenna system (PSII antenna uncoupling). The extent of antenna uncoupling largely depends on the light regime, reaching the highest value in sun-acclimated plants. In parallel, the photoprotective NPQ (pNPQ) increased from deep-shade to high-light grown plants. It is proposed that the differences in the long-term modulation in the photoprotective capacity are proportional to the amount of uncoupled LHCII. In deep-shade plants, the inconsistency between invariable maximum NPQ and lower pNPQ is attributed to the thermal dissipation occurring in the PSII core.
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Affiliation(s)
- Andrea Colpo
- Department of Environmental and Prevention SciencesUniversity of FerraraFerrara
| | | | - Simonetta Pancaldi
- Department of Environmental and Prevention SciencesUniversity of FerraraFerrara
| | - Alessandra Sabia
- Department of Environmental and Prevention SciencesUniversity of FerraraFerrara
| | - Lorenzo Ferroni
- Department of Environmental and Prevention SciencesUniversity of FerraraFerrara
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Yang YJ, Sun H, Zhang SB, Huang W. Roles of alternative electron flows in response to excess light in Ginkgo biloba. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2021; 312:111030. [PMID: 34620434 DOI: 10.1016/j.plantsci.2021.111030] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 08/17/2021] [Accepted: 08/20/2021] [Indexed: 06/13/2023]
Abstract
Ginkgo biloba L., the only surviving species of Ginkgoopsida, is a famous relict gymnosperm, it may provide new insight into the evolution of photosynthetic mechanisms. Flavodiiron proteins (FDPs) are conserved in nonflowering plants, but the role of FDPs in gymnosperms has not yet been clarified. In particular, how gymnosperms integrate FDPs and cyclic electron transport (CET) to better adapt to excess light is poorly understood. To elucidate these questions, we measured the P700 signal, chlorophyll fluorescence and electrochromic shift signal under fluctuating and constant light in G. biloba. Within the first seconds after light increased, G. biloba could not build up a sufficient proton gradient (ΔpH). Concomitantly, photo-reduction of O2 mediated by FDPs contributed to the rapid oxidation of P700 and protected PSI under fluctuating light. Therefore, in G. biloba, FDPs mainly protect PSI under fluctuating light at acceptor side. Under constant high light, the oxidation of PSI and the induction of non-photochemical quenching were attributed to the increase in ΔpH formation, which was mainly caused by the increase in CET rather than linear electron transport. Therefore, under constant light, CET finely regulates the PSI redox state and non-photochemical quenching through ΔpH formation, protecting PSI and PSII against excess light. We conclude that, in G. biloba, FDPs are particularly important under fluctuating light while CET is essential under constant high light. The coordination of FDPs and CET fine-tune photosynthetic apparatus under excess light.
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Affiliation(s)
- Ying-Jie Yang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Hu Sun
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shi-Bao Zhang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China
| | - Wei Huang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China.
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Li H, Li J, Zhang X, Shi T, Chai X, Hou P, Wang Y. Mesophyll conductance, photoprotective process and optimal N partitioning are essential to the maintenance of photosynthesis at N deficient condition in a wheat yellow-green mutant (Triticum aestivum L.). JOURNAL OF PLANT PHYSIOLOGY 2021; 263:153469. [PMID: 34252704 DOI: 10.1016/j.jplph.2021.153469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 06/28/2021] [Accepted: 06/28/2021] [Indexed: 06/13/2023]
Abstract
The major effect of nitrogen (N) deficiency is the inhibition on CO2 assimilation regulated by light energy absorption, transport and conversion, as well as N allocation. In this study, a yellow-green wheat mutant (Jimai5265yg) and its wild type (Jimai5265, WT) were compared between 0 mM N (N0) and 14 mM N (N14) treatments using hydroponic experiments. The mutant exhibited higher photosynthetic efficiency (An) than WT despite low chlorophyll (Chl) content in non-stressed conditions. The photosynthetic advantages of the mutant were maintained under N deficient condition. The quantitative analysis of limitations to photosynthesis revealed that CO2 diffusion associated with mesophyll conductance (gm) was the dominant limitation. Relative easiness to gain CO2 in the chloroplast contributed to the higher An of Jimai5265yg. N deficiency induced the photoinhibition of PSII, but the cyclic electron transport and photochemical activity of PSI was higher in Jimai5265yg compared to Jimai5265, which was a protective mechanism to avoid photodamage. Because of the sharp drop of An, N deficient seedlings had much lower photosynthetic N use efficiency (PNUE). However, N deficiency increased the relative content of photosynthetic N (Npsn) and decreased the relative content of storage N (Nstore). The range of change in N partitioning induced by N deficiency was smaller for Jimai5265yg compared to WT. The less insensitive to N deficiency for the mutant in terms of photosynthetic property and N partitioning suggested that gm, cyclic electron transport around PSI and more optimal N partitioning pattern is necessary to sustain photosynthesis under N deficient condition.
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Affiliation(s)
- Hongxia Li
- College of Agronomy, Northwest A&F University, Yangling, Shaanxi, 712100, PR China
| | - Junjie Li
- College of Agronomy, Northwest A&F University, Yangling, Shaanxi, 712100, PR China
| | - Xuhui Zhang
- College of Agronomy, Northwest A&F University, Yangling, Shaanxi, 712100, PR China
| | - Tingrui Shi
- College of Agronomy, Northwest A&F University, Yangling, Shaanxi, 712100, PR China
| | - Xinyu Chai
- College of Agronomy, Northwest A&F University, Yangling, Shaanxi, 712100, PR China
| | - Peijia Hou
- College of Agronomy, Northwest A&F University, Yangling, Shaanxi, 712100, PR China
| | - Yu Wang
- College of Agronomy, Northwest A&F University, Yangling, Shaanxi, 712100, PR China.
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