1
|
Domínguez F, Cejudo FJ. Chloroplast dismantling in leaf senescence. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:5905-5918. [PMID: 33959761 PMCID: PMC8760853 DOI: 10.1093/jxb/erab200] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 05/03/2021] [Indexed: 05/02/2023]
Abstract
In photosynthetic plant cells, chloroplasts act as factories of metabolic intermediates that support plant growth. Chloroplast performance is highly influenced by environmental cues. Thus, these organelles have the additional function of sensing ever changing environmental conditions, thereby playing a key role in harmonizing the growth and development of different organs and in plant acclimation to the environment. Moreover, chloroplasts constitute an excellent source of metabolic intermediates that are remobilized to sink tissues during senescence so that chloroplast dismantling is a tightly regulated process that plays a key role in plant development. Stressful environmental conditions enhance the generation of reactive oxygen species (ROS) by chloroplasts, which may lead to oxidative stress causing damage to the organelle. These environmental conditions trigger mechanisms that allow the rapid dismantling of damaged chloroplasts, which is crucial to avoid deleterious effects of toxic by-products of the degradative process. In this review, we discuss the effect of redox homeostasis and ROS generation in the process of chloroplast dismantling. Furthermore, we summarize the structural and biochemical events, both intra- and extraplastid, that characterize the process of chloroplast dismantling in senescence and in response to environmental stresses.
Collapse
Affiliation(s)
- Fernando Domínguez
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla and Consejo Superior de Investigaciones Científicas, Avda. Américo Vespucio 49, 41092-Sevilla, Spain
| | | |
Collapse
|
2
|
Wu G, Ma L, Yuan C, Dai J, Luo L, Poudyal RS, Sayre RT, Lee CH. Formation of light-harvesting complex II aggregates from LHCII-PSI-LHCI complexes in rice plants under high light. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:4938-4948. [PMID: 33939808 DOI: 10.1093/jxb/erab188] [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: 01/29/2021] [Accepted: 05/01/2021] [Indexed: 06/12/2023]
Abstract
During low light- (LL) induced state transitions in dark-adapted rice (Oryza sativa) leaves, light-harvesting complex (LHC) II become phosphorylated and associate with PSI complexes to form LHCII-PSI-LHCI supercomplexes. When the leaves are subsequently transferred to high light (HL) conditions, phosphorylated LHCII complexes are no longer phosphorylated. Under the HL-induced transition in LHC phosphorylation status, we observed a new green band in the stacking gel of native green-PAGE, which was determined to be LHCII aggregates by immunoblotting and 77K chlorophyll fluorescence analysis. Knockout mutants of protein phosphatase 1 (PPH1) which dephosphorylates LHCII failed to form these LHCII aggregates. In addition, the ability to develop non-photochemical quenching in the PPH1 mutant under HL was less than for wild-type plants. As determined by immunoblotting analysis, LHCII proteins present in LHCII-PSI-LHCI supercomplexes included the Lhcb1 and Lhcb2 proteins. In this study, we provide evidence suggesting that LHCII in the LHCII-PSI-LHCI supercomplexes are dephosphorylated and subsequently form aggregates to dissipate excess light energy under HL conditions. We propose that this LHCII aggregation, involving LHCII L-trimers, is a newly observed photoprotective light-quenching process operating in the early stage of acclimation to HL in rice plants.
Collapse
Affiliation(s)
- Guangxi Wu
- Department of Molecular Biology, Pusan National University, Busan, Republic of Korea
| | - Lin Ma
- Department of Molecular Biology, Pusan National University, Busan, Republic of Korea
| | - Cai Yuan
- Department of Molecular Biology, Pusan National University, Busan, Republic of Korea
| | - Jiahao Dai
- Department of Molecular Biology, Pusan National University, Busan, Republic of Korea
| | - Lai Luo
- Department of Molecular Biology, Pusan National University, Busan, Republic of Korea
| | - Roshan Sharma Poudyal
- Department of Molecular Biology, Pusan National University, Busan, Republic of Korea
| | | | - Choon-Hwan Lee
- Department of Molecular Biology, Pusan National University, Busan, Republic of Korea
| |
Collapse
|
3
|
Guyer L, Salinger K, Krügel U, Hörtensteiner S. Catalytic and structural properties of pheophytinase, the phytol esterase involved in chlorophyll breakdown. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:879-889. [PMID: 29036670 PMCID: PMC5853334 DOI: 10.1093/jxb/erx326] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 08/21/2017] [Indexed: 05/22/2023]
Abstract
During leaf senescence and fruit ripening, chlorophyll is degraded in a multistep pathway into linear tetrapyrroles called phyllobilins. A key feature of chlorophyll breakdown is the removal of the hydrophobic phytol chain that renders phyllobilins water soluble, an important prerequisite for their ultimate storage in the vacuole of senescent cells. Chlorophyllases had been considered for more than a century to catalyze dephytylation in vivo; however, this was recently refuted. Instead, pheophytinase was discovered as a genuine in vivo phytol hydrolase. While chlorophyllase acts rather unspecifically towards different porphyrin substrates, pheophytinase was shown to specifically dephytylate pheophytin, namely Mg-free chlorophyll. The aim of this work was to elucidate in detail the biochemical and structural properties of pheophytinase. By testing different porphyrin substrates with recombinant pheophytinase from Arabidopsis thaliana we show that pheophytinase has high specificity for the acid moiety of the ester bond, namely the porphyrin ring, while the nature of the alcohol, namely the phytol chain in pheophytin, is irrelevant. In silico modelling of the 3-dimensional structure of pheophytinase and subsequent analysis of site-directed pheophytinase mutant forms allowed the identification of the serine, histidine, and aspartic acid residues that compose the catalytic triad, a classical feature of serine-type hydrolases to which both pheophytinase and chlorophyllase belong. Based on substantial structural differences in the models of Arabidopsis pheophytinase and chlorophyllase 1, we discuss potential differences in the catalytic properties of these two phytol hydrolases.
Collapse
Affiliation(s)
- Luzia Guyer
- Institute of Plant and Microbial Biology, University of Zurich, Zollikerstrasse, Zurich, Switzerland
| | - Kathrin Salinger
- Institute of Plant and Microbial Biology, University of Zurich, Zollikerstrasse, Zurich, Switzerland
| | - Undine Krügel
- Institute of Plant and Microbial Biology, University of Zurich, Zollikerstrasse, Zurich, Switzerland
| | - Stefan Hörtensteiner
- Institute of Plant and Microbial Biology, University of Zurich, Zollikerstrasse, Zurich, Switzerland
| |
Collapse
|
4
|
Kalaji HM, Schansker G, Brestic M, Bussotti F, Calatayud A, Ferroni L, Goltsev V, Guidi L, Jajoo A, Li P, Losciale P, Mishra VK, Misra AN, Nebauer SG, Pancaldi S, Penella C, Pollastrini M, Suresh K, Tambussi E, Yanniccari M, Zivcak M, Cetner MD, Samborska IA, Stirbet A, Olsovska K, Kunderlikova K, Shelonzek H, Rusinowski S, Bąba W. Frequently asked questions about chlorophyll fluorescence, the sequel. PHOTOSYNTHESIS RESEARCH 2017; 132:13-66. [PMID: 27815801 PMCID: PMC5357263 DOI: 10.1007/s11120-016-0318-y] [Citation(s) in RCA: 221] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Accepted: 10/17/2016] [Indexed: 05/20/2023]
Abstract
Using chlorophyll (Chl) a fluorescence many aspects of the photosynthetic apparatus can be studied, both in vitro and, noninvasively, in vivo. Complementary techniques can help to interpret changes in the Chl a fluorescence kinetics. Kalaji et al. (Photosynth Res 122:121-158, 2014a) addressed several questions about instruments, methods and applications based on Chl a fluorescence. Here, additional Chl a fluorescence-related topics are discussed again in a question and answer format. Examples are the effect of connectivity on photochemical quenching, the correction of F V /F M values for PSI fluorescence, the energy partitioning concept, the interpretation of the complementary area, probing the donor side of PSII, the assignment of bands of 77 K fluorescence emission spectra to fluorescence emitters, the relationship between prompt and delayed fluorescence, potential problems when sampling tree canopies, the use of fluorescence parameters in QTL studies, the use of Chl a fluorescence in biosensor applications and the application of neural network approaches for the analysis of fluorescence measurements. The answers draw on knowledge from different Chl a fluorescence analysis domains, yielding in several cases new insights.
Collapse
Affiliation(s)
- Hazem M. Kalaji
- Department of Plant Physiology, Faculty of Agriculture and Biology, Warsaw University of Life Sciences – SGGW, Nowoursynowska 159, 02-776 Warsaw, Poland
| | | | - Marian Brestic
- Department of Plant Physiology, Slovak Agricultural University, Tr. A. Hlinku 2, 949 76 Nitra, Slovak Republic
| | - Filippo Bussotti
- Department of Agricultural, Food and Environmental Sciences, University of Florence, Piazzale delle Cascine 28, 50144 Florence, Italy
| | - Angeles Calatayud
- Departamento de Horticultura, Instituto Valenciano de Investigaciones Agrarias, Ctra. Moncada-Náquera Km 4.5., 46113 Moncada, Valencia Spain
| | - Lorenzo Ferroni
- Department of Life Sciences and Biotechnology, University of Ferrara, Corso Ercole I d’Este, 32, 44121 Ferrara, Italy
| | - Vasilij Goltsev
- Department of Biophysics and Radiobiology, Faculty of Biology, St. Kliment Ohridski University of Sofia, 8 Dr.Tzankov Blvd., 1164 Sofia, Bulgaria
| | - Lucia Guidi
- Department of Agriculture, Food and Environment, Via del Borghetto, 80, 56124 Pisa, Italy
| | - Anjana Jajoo
- School of Life Sciences, Devi Ahilya University, Indore, M.P. 452 001 India
| | - Pengmin Li
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling, 712100 Shaanxi China
| | - Pasquale Losciale
- Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria [Research Unit for Agriculture in Dry Environments], 70125 Bari, Italy
| | - Vinod K. Mishra
- Department of Biotechnology, Doon (P.G.) College of Agriculture Science, Dehradun, Uttarakhand 248001 India
| | - Amarendra N. Misra
- Centre for Life Sciences, Central University of Jharkhand, Ratu-Lohardaga Road, Ranchi, 835205 India
| | - Sergio G. Nebauer
- Departamento de Producción vegetal, Universitat Politècnica de València, Camino de Vera sn., 46022 Valencia, Spain
| | - Simonetta Pancaldi
- Department of Life Sciences and Biotechnology, University of Ferrara, Corso Ercole I d’Este, 32, 44121 Ferrara, Italy
| | - Consuelo Penella
- Departamento de Horticultura, Instituto Valenciano de Investigaciones Agrarias, Ctra. Moncada-Náquera Km 4.5., 46113 Moncada, Valencia Spain
| | - Martina Pollastrini
- Department of Agricultural, Food and Environmental Sciences, University of Florence, Piazzale delle Cascine 28, 50144 Florence, Italy
| | - Kancherla Suresh
- ICAR – Indian Institute of Oil Palm Research, Pedavegi, West Godavari Dt., Andhra Pradesh 534 450 India
| | - Eduardo Tambussi
- Institute of Plant Physiology, INFIVE (Universidad Nacional de La Plata — Consejo Nacional de Investigaciones Científicas y Técnicas), Diagonal 113 N°495, CC 327, La Plata, Argentina
| | - Marcos Yanniccari
- Institute of Plant Physiology, INFIVE (Universidad Nacional de La Plata — Consejo Nacional de Investigaciones Científicas y Técnicas), Diagonal 113 N°495, CC 327, La Plata, Argentina
| | - Marek Zivcak
- Department of Plant Physiology, Slovak Agricultural University, Tr. A. Hlinku 2, 949 76 Nitra, Slovak Republic
| | - Magdalena D. Cetner
- Department of Plant Physiology, Faculty of Agriculture and Biology, Warsaw University of Life Sciences – SGGW, Nowoursynowska 159, 02-776 Warsaw, Poland
| | - Izabela A. Samborska
- Department of Plant Physiology, Faculty of Agriculture and Biology, Warsaw University of Life Sciences – SGGW, Nowoursynowska 159, 02-776 Warsaw, Poland
| | | | - Katarina Olsovska
- Department of Plant Physiology, Slovak University of Agriculture, A. Hlinku 2, 94976 Nitra, Slovak Republic
| | - Kristyna Kunderlikova
- Department of Plant Physiology, Slovak University of Agriculture, A. Hlinku 2, 94976 Nitra, Slovak Republic
| | - Henry Shelonzek
- Department of Plant Anatomy and Cytology, Faculty of Biology and Environmental Protection, University of Silesia, ul. Jagiellońska 28, 40-032 Katowice, Poland
| | - Szymon Rusinowski
- Institute for Ecology of Industrial Areas, Kossutha 6, 40-844 Katowice, Poland
| | - Wojciech Bąba
- Department of Plant Ecology, Institute of Botany, Jagiellonian University, Lubicz 46, 31-512 Kraków, Poland
| |
Collapse
|
5
|
Li Z, Peng J, Wen X, Guo H. Ethylene-insensitive3 is a senescence-associated gene that accelerates age-dependent leaf senescence by directly repressing miR164 transcription in Arabidopsis. THE PLANT CELL 2013; 25:3311-28. [PMID: 24064769 PMCID: PMC3809534 DOI: 10.1105/tpc.113.113340] [Citation(s) in RCA: 275] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 07/14/2013] [Accepted: 09/10/2013] [Indexed: 05/18/2023]
Abstract
Numerous endogenous and environmental signals regulate the intricate and highly orchestrated process of plant senescence. Ethylene is a well-known inducer of senescence, including fruit ripening and flower and leaf senescence. However, the underlying molecular mechanism of ethylene-induced leaf senescence remains to be elucidated. Here, we examine ethylene-insensitive3 (EIN3), a key transcription factor in ethylene signaling, and find that EIN3 is a functional senescence-associated gene. Constitutive overexpression or temporary activation of EIN3 is sufficient to accelerate leaf senescence symptoms. Conversely, loss of EIN3 and EIN3-Like1 (its close homolog) function leads to a delay in age-dependent and ethylene-, jasmonic acid-, or dark-induced leaf senescence. We further found that EIN3 acts downstream of ORESARA2 (ORE2)/ORE3/EIN2 to repress miR164 transcription and upregulate the transcript levels of ORE1/NAC2, a target gene of miR164. EIN3 directly binds to the promoters of microRNA164 (miR164), and this binding activity progressively increases during leaf ageing. Genetic analysis revealed that overexpression of miR164 or knockout of ORE1/NAC2 represses EIN3-induced early-senescence phenotypes. Collectively, our study defines a continuation of the signaling pathway involving EIN2-EIN3-miR164-NAC2 in regulating leaf senescence and provides a mechanistic insight into how ethylene promotes the progression of leaf senescence in Arabidopsis thaliana.
Collapse
Affiliation(s)
- Zhonghai Li
- State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
- Peking-Tsinghua Center of Life Sciences, Beijing 100871, China
| | - Jinying Peng
- State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
- Peking-Tsinghua Center of Life Sciences, Beijing 100871, China
| | - Xing Wen
- State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
- Peking-Tsinghua Center of Life Sciences, Beijing 100871, China
| | - Hongwei Guo
- State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
- Peking-Tsinghua Center of Life Sciences, Beijing 100871, China
- Address correspondence to
| |
Collapse
|
6
|
Hörtensteiner S. Update on the biochemistry of chlorophyll breakdown. PLANT MOLECULAR BIOLOGY 2013; 82:505-17. [PMID: 22790503 DOI: 10.1007/s11103-012-9940-z] [Citation(s) in RCA: 115] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Accepted: 06/28/2012] [Indexed: 05/18/2023]
Abstract
In land plants, chlorophyll is broken down to colorless linear tetrapyrroles in a highly conserved multi-step pathway. The pathway is termed the 'PAO pathway', because the opening of the chlorine macrocycle present in chlorophyll catalyzed by pheophorbide a oxygenase (PAO), the key enzyme of the pathway, provides the characteristic structural basis found in all further downstream chlorophyll breakdown products. To date, most of the biochemical steps of the PAO pathway have been elucidated and genes encoding many of the chlorophyll catabolic enzymes been identified. This review summarizes the current knowledge on the biochemistry of the PAO pathway and provides insight into recent progress made in the field that indicates that the pathway is more complex than thought in the past.
Collapse
Affiliation(s)
- Stefan Hörtensteiner
- Institute of Plant Biology, University of Zurich, Zollikerstrasse 107, 8008, Zurich, Switzerland.
| |
Collapse
|
7
|
Hörtensteiner S. The Pathway of Chlorophyll Degradation: Catabolites, Enzymes and Pathway Regulation. PLASTID DEVELOPMENT IN LEAVES DURING GROWTH AND SENESCENCE 2013. [DOI: 10.1007/978-94-007-5724-0_16] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
|
8
|
Ruban AV, Johnson MP, Duffy CDP. The photoprotective molecular switch in the photosystem II antenna. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1817:167-81. [PMID: 21569757 DOI: 10.1016/j.bbabio.2011.04.007] [Citation(s) in RCA: 493] [Impact Index Per Article: 37.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Revised: 03/28/2011] [Accepted: 04/01/2011] [Indexed: 10/18/2022]
Abstract
We have reviewed the current state of multidisciplinary knowledge of the photoprotective mechanism in the photosystem II antenna underlying non-photochemical chlorophyll fluorescence quenching (NPQ). The physiological need for photoprotection of photosystem II and the concept of feed-back control of excess light energy are described. The outline of the major component of nonphotochemical quenching, qE, is suggested to comprise four key elements: trigger (ΔpH), site (antenna), mechanics (antenna dynamics) and quencher(s). The current understanding of the identity and role of these qE components is presented. Existing opinions on the involvement of protons, different LHCII antenna complexes, the PsbS protein and different xanthophylls are reviewed. The evidence for LHCII aggregation and macrostructural reorganization of photosystem II and their role in qE are also discussed. The models describing the qE locus in LHCII complexes, the pigments involved and the evidence for structural dynamics within single monomeric antenna complexes are reviewed. We suggest how PsbS and xanthophylls may exert control over qE by controlling the affinity of LHCII complexes for protons with reference to the concepts of hydrophobicity, allostery and hysteresis. Finally, the physics of the proposed chlorophyll-chlorophyll and chlorophyll-xanthophyll mechanisms of energy quenching is explained and discussed. This article is part of a Special Issue entitled: Photosystem II.
Collapse
Affiliation(s)
- Alexander V Ruban
- Queen Mary Universityof London, School of Biological & Chemical Sciences, Mile Enf Road, London E1 4TN, UK.
| | | | | |
Collapse
|
9
|
Consonni C, Bednarek P, Humphry M, Francocci F, Ferrari S, Harzen A, Ver Loren van Themaat E, Panstruga R. Tryptophan-derived metabolites are required for antifungal defense in the Arabidopsis mlo2 mutant. PLANT PHYSIOLOGY 2010; 152:1544-61. [PMID: 20023151 PMCID: PMC2832281 DOI: 10.1104/pp.109.147660] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Accepted: 12/14/2009] [Indexed: 05/18/2023]
Abstract
Arabidopsis (Arabidopsis thaliana) genes MILDEW RESISTANCE LOCUS O2 (MLO2), MLO6, and MLO12 exhibit unequal genetic redundancy with respect to the modulation of defense responses against powdery mildew fungi and the control of developmental phenotypes such as premature leaf decay. We show that early chlorosis and necrosis of rosette leaves in mlo2 mlo6 mlo12 mutants reflects an authentic but untimely leaf senescence program. Comparative transcriptional profiling revealed that transcripts of several genes encoding tryptophan biosynthetic and metabolic enzymes hyperaccumulate during vegetative development in the mlo2 mlo6 mlo12 mutant. Elevated expression levels of these genes correlate with altered steady-state levels of several indolic metabolites, including the phytoalexin camalexin and indolic glucosinolates, during development in the mlo2 single mutant and the mlo2 mlo6 mlo12 triple mutant. Results of genetic epistasis analysis suggest a decisive role for indolic metabolites in mlo2-conditioned antifungal defense against both biotrophic powdery mildews and a camalexin-sensitive strain of the necrotrophic fungus Botrytis cinerea. The wound- and pathogen-responsive callose synthase POWDERY MILDEW RESISTANCE4/GLUCAN SYNTHASE-LIKE5 was found to be responsible for the spontaneous callose deposits in mlo2 mutant plants but dispensable for mlo2-conditioned penetration resistance. Our data strengthen the notion that powdery mildew resistance of mlo2 genotypes is based on the same defense execution machinery as innate antifungal immune responses that restrict the invasion of nonadapted fungal pathogens.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | - Ralph Panstruga
- Department of Plant-Microbe Interactions (C.C., P.B., M.H., E.V.L.v.T., R.P.) and Mass Spectrometry Group (A.H.), Max-Planck Institute for Plant Breeding Research, D–50829 Cologne, Germany; and Dipartimento di Biologia Vegetale, Sapienza Università di Roma, 00185 Rome, Italy (F.F., S.F.)
| |
Collapse
|
10
|
Heat-induced disassembly and degradation of chlorophyll-containing protein complexes in vivo. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:63-70. [DOI: 10.1016/j.bbabio.2009.08.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Revised: 08/12/2009] [Accepted: 08/18/2009] [Indexed: 11/19/2022]
|
11
|
Pantaleoni L, Ferroni L, Baldisserotto C, Aro EM, Pancaldi S. Photosystem II organisation in chloroplasts of Arum italicum leaf depends on tissue location. PLANTA 2009; 230:1019-1031. [PMID: 19705147 DOI: 10.1007/s00425-009-1004-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Accepted: 08/05/2009] [Indexed: 05/27/2023]
Abstract
The growth of plants under stable light quality induces long-term acclimation responses of the photosynthetic apparatus. Light can even cause variations depending on the tissue location, as in Arum italicum leaf, where chloroplasts are developed in the lamina and in the entire thickness of the petiole. We addressed the question whether differences in plastids can be characterised in terms of protein-protein interactions in the thylakoid membranes. Thylakoid assembly was studied in the palisade and spongy tissue of the lamina and in the outer parenchyma and inner aerenchyma of the petiole of the mature winter leaf of Arum italicum. The chlorophyll-protein complexes were analysed by means of blue-native-PAGE and fluorescence emission spectra. The petiole chloroplasts differ from those in the lamina in thylakoid composition: (1) reaction centres are scarce, especially photosystem (PS) I in the inner aerenchyma; (2) light-harvesting complex (LHC) II is abundant, (3) the relative amount of LHCII trimers increases, but this is not accompanied by increased levels of PSII-LHCII supercomplexes. Nevertheless, the intrinsic PSII functionality is comparable in all tissues. In Arum italicum leaf, the gradient in thylakoid organisation, which occurs from the palisade tissue to the inner aerenchyma of the petiole, is typical for photosynthetic acclimation to low-light intensity with a high enrichment of far-red light. The results obtained demonstrate a high plasticity of chloroplasts even in an individual plant. The mutual interaction of thylakoid protein complexes is discussed in relation to the photosynthetic efficiency of the leaf parts and to the ecodevelopmental role of light.
Collapse
Affiliation(s)
- Laura Pantaleoni
- Department of Biology and Evolution, University of Ferrara, 44100 Ferrara, Italy
| | | | | | | | | |
Collapse
|
12
|
Ferroni L, Baldisserotto C, Pantaleoni L, Fasulo MP, Fagioli P, Pancaldi S. Degreening of the unicellular alga Euglena gracilis: thylakoid composition, room temperature fluorescence spectra and chloroplast morphology. PLANT BIOLOGY (STUTTGART, GERMANY) 2009; 11:631-41. [PMID: 19538401 DOI: 10.1111/j.1438-8677.2008.00152.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Thylakoid dismantling is one of the most relevant processes occurring when chloroplasts are converted to non-photosynthetically active plastids. The process is well characterised in senescing leaves, but other systems could present different features. In this study, thylakoid dismantling has been analysed in dividing cells of the unicellular alga, Euglena gracilis, cultured in darkness. Changes in photosynthetic pigments and in the abundance of LHC and PSII core proteins (D2 and CP43) showed that: (i) during the 0-24 h interval, the decline in LHCII was faster than that in the PSII core; (ii) during the 24-48 h interval, PSII and LHCII were strongly degraded to nearly the same extent; (iii) in the 48-72 h interval, the PSII core proteins declined markedly, while LHCII was maintained. These changes were accompanied by variations in room temperature fluorescence emission spectra recorded from single living cells with a microspectrofluorimeter (excitation, 436 nm; range 620-780 nm). Emission in the 700-715 nm range was proposed to derive from LHCI-II assemblages; changes in emission at 678 nm relative to PSII matched PSII core degradation phases. Overall, the results suggest that, in degreening E. gracilis, thylakoid dismantling is somewhat different from that associated with senescence, because of the early loss of LHCII. Moreover, it is proposed that, in this alga, disruption of the correct LHCI-II stoichiometry alters the energy transfer to photosystems and destabilises membrane appression leading to the thylakoid destacking observed using transmission electron microscopy.
Collapse
Affiliation(s)
- L Ferroni
- Laboratory of Plant Cytophysiology, Department of Biology and Evolution, University of Ferrara, Ferrara, Italy
| | | | | | | | | | | |
Collapse
|
13
|
Oh MH, Safarova RB, Eu YJ, Zulfugarov IS, Kim JH, Hwang HJ, Lee CB, Lee CH. Loss of peripheral polypeptides in the stromal side of photosystem I by light-chilling in cucumber leaves. Photochem Photobiol Sci 2009; 8:535-41. [PMID: 19337668 DOI: 10.1039/b817808a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Accepted: 01/30/2009] [Indexed: 11/21/2022]
Abstract
Photosystem I (PSI) is severely damaged by chilling at 4 degrees C in low light, especially in the chilling sensitive plant cucumber. To investigate the early events in PSI photoinhibition, we examined structural changes in the level of pigment-protein complexes in cucumber leaves in comparison with pea leaves. The complexes were separated on a native green gel and an increase in the intensity of a band was observed only in light-chilled cucumber leaves. The 77 K fluorescence emission spectrum of this green band indicated that the band was mainly composed of PSI with light-harvesting complex I. Each lane was cut from the green gel and separated on a fully denaturing SDS-PAGE in the second dimension. The new green gel band observed after light-chilling in cucumber leaves lacked 19, 18, and 16.5 kDa polypeptides. These results suggest that light-chilling facilitates the release of three peripheral polypeptides as an early event of chilling stress in vivo, which results in the inactivation of PSI in intact cucumber leaves.
Collapse
Affiliation(s)
- Min-Hyuk Oh
- Department of Molecular Biology, Pusan National University, Busan 609-735, Korea
| | | | | | | | | | | | | | | |
Collapse
|
14
|
Hörtensteiner S. Stay-green regulates chlorophyll and chlorophyll-binding protein degradation during senescence. TRENDS IN PLANT SCIENCE 2009; 14:155-62. [PMID: 19237309 DOI: 10.1016/j.tplants.2009.01.002] [Citation(s) in RCA: 214] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2008] [Revised: 01/06/2009] [Accepted: 01/08/2009] [Indexed: 05/18/2023]
Abstract
Stay-green mutants are delayed in leaf senescence and have been identified from different plant species, including many crops. Functional stay-greens have the potential to increase plant productivity. In cosmetic stay-greens, however, retention of chlorophyll during senescence is uncoupled from a decline of photosynthetic capacity in these mutants. For many cosmetic stay-green mutants, including Gregor Mendel's famous green cotyledon pea variety, molecular defects were recently identified in orthologous stay-green genes. Stay-green genes encode members of a new family of chloroplast-located proteins, which are likely to function in dismantling of photosynthetic chlorophyll-apoprotein complexes. Their activity is considered as a prerequisite for both chlorophyll and apoprotein degradation during senescence.
Collapse
Affiliation(s)
- Stefan Hörtensteiner
- Zurich-Basel Plant Science Center, Institute of Plant Biology, University of Zurich, CH-8008 Zurich, Switzerland.
| |
Collapse
|
15
|
Schelbert S, Aubry S, Burla B, Agne B, Kessler F, Krupinska K, Hörtensteiner S. Pheophytin pheophorbide hydrolase (pheophytinase) is involved in chlorophyll breakdown during leaf senescence in Arabidopsis. THE PLANT CELL 2009; 21:767-85. [PMID: 19304936 PMCID: PMC2671698 DOI: 10.1105/tpc.108.064089] [Citation(s) in RCA: 331] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2008] [Revised: 02/12/2009] [Accepted: 03/08/2009] [Indexed: 05/08/2023]
Abstract
During leaf senescence, chlorophyll is removed from thylakoid membranes and converted in a multistep pathway to colorless breakdown products that are stored in vacuoles. Dephytylation, an early step of this pathway, increases water solubility of the breakdown products. It is widely accepted that chlorophyll is converted into pheophorbide via chlorophyllide. However, chlorophyllase, which converts chlorophyll to chlorophyllide, was found not to be essential for dephytylation in Arabidopsis thaliana. Here, we identify pheophytinase (PPH), a chloroplast-located and senescence-induced hydrolase widely distributed in algae and land plants. In vitro, Arabidopsis PPH specifically dephytylates the Mg-free chlorophyll pigment, pheophytin (phein), yielding pheophorbide. An Arabidopsis mutant deficient in PPH (pph-1) is unable to degrade chlorophyll during senescence and therefore exhibits a stay-green phenotype. Furthermore, pph-1 accumulates phein during senescence. Therefore, PPH is an important component of the chlorophyll breakdown machinery of senescent leaves, and we propose that the sequence of early chlorophyll catabolic reactions be revised. Removal of Mg most likely precedes dephytylation, resulting in the following order of early breakdown intermediates: chlorophyll --> pheophytin --> pheophorbide. Chlorophyllide, the last precursor of chlorophyll biosynthesis, is most likely not an intermediate of breakdown. Thus, chlorophyll anabolic and catabolic reactions are metabolically separated.
Collapse
Affiliation(s)
- Silvia Schelbert
- Institute of Plant Biology, University of Zürich, CH-8008 Zurich, Switzerland
| | | | | | | | | | | | | |
Collapse
|
16
|
Alós E, Roca M, Iglesias DJ, Mínguez-Mosquera MI, Damasceno CMB, Thannhauser TW, Rose JKC, Talón M, Cercós M. An evaluation of the basis and consequences of a stay-green mutation in the navel negra citrus mutant using transcriptomic and proteomic profiling and metabolite analysis. PLANT PHYSIOLOGY 2008; 147:1300-15. [PMID: 18467459 PMCID: PMC2442528 DOI: 10.1104/pp.108.119917] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2008] [Accepted: 05/05/2008] [Indexed: 05/20/2023]
Abstract
A Citrus sinensis spontaneous mutant, navel negra (nan), produces fruit with an abnormal brown-colored flavedo during ripening. Analysis of pigment composition in the wild-type and nan flavedo suggested that typical ripening-related chlorophyll (Chl) degradation, but not carotenoid biosynthesis, was impaired in the mutant, identifying nan as a type C stay-green mutant. nan exhibited normal expression of Chl biosynthetic and catabolic genes and chlorophyllase activity but no accumulation of dephytylated Chl compounds during ripening, suggesting that the mutation is not related to a lesion in any of the principal enzymatic steps in Chl catabolism. Transcript profiling using a citrus microarray indicated that a citrus ortholog of a number of SGR (for STAY-GREEN) genes was expressed at substantially lower levels in nan, both prior to and during ripening. However, the pattern of catabolite accumulation and SGR sequence analysis suggested that the nan mutation is distinct from those in previously described stay-green mutants and is associated with an upstream regulatory step, rather than directly influencing a specific component of Chl catabolism. Transcriptomic and comparative proteomic profiling further indicated that the nan mutation resulted in the suppressed expression of numerous photosynthesis-related genes and in the induction of genes that are associated with oxidative stress. These data, along with metabolite analyses, suggest that nan fruit employ a number of molecular mechanisms to compensate for the elevated Chl levels and associated photooxidative stress.
Collapse
Affiliation(s)
- Enriqueta Alós
- Instituto Valenciano de Investigaciones Agrarias, Centro de Genómica, 46113 Moncada, Valencia, Spain
| | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Jiang H, Li M, Liang N, Yan H, Wei Y, Xu X, Liu J, Xu Z, Chen F, Wu G. Molecular cloning and function analysis of the stay green gene in rice. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2007; 52:197-209. [PMID: 17714430 DOI: 10.1111/j.1365-313x.2007.03221.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Chloroplasts undergo drastic morphological and physiological changes during senescence with a visible symptom of chlorophyll (Chl) degradation. A stay green mutant was identified and then isolated from the japonica rice (Oryza sativa) cv. Huazhiwu by gamma-ray irradiation. The stay green mutant was characterized by Chl retention, stable Chl-protein complexes, and stable thylakoid membrane structures, but lost its photosynthetic competence during senescence. The gene, designated Stay Green Rice (SGR), was cloned by a positional cloning strategy encoding an ancient protein containing a putative chloroplast transit peptide. SGR protein was found in both soluble and thylakoid membranes in rice. SGR, like the gene for pheophorbide a oxygenase (PaO), was constitutively expressed, but was upregulated by dark-induced senescence in rice leaves. Senescence-induced expression of SGR and PaO was enhanced by ABA, but inhibited by cytokinin. Overexpression of SGR reduced the number of lamellae in the grana thylakoids and reduced the Chl content of normally growing leaves. This indicates that upregulation of SGR increases Chl breakdown during senescence in rice. A small quantity of chlorophyllide a accumulated in sgr leaves, but this also accumulated in wild-type rice leaves during senescence. Some pheophorbide a was detected in sgr leaves in the dark. According to these observations, we propose that SGR may be involved in regulating or taking part in the activity of PaO, and then may influence Chl breakdown and degradation of pigment-protein complex.
Collapse
Affiliation(s)
- Huawu Jiang
- South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
| | | | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Ananieva K, Ananiev ED, Mishev K, Georgieva K, Malbeck J, Kamínek M, Van Staden J. Methyl jasmonate is a more effective senescence-promoting factor in Cucurbita pepo (zucchini) cotyledons when compared with darkness at the early stage of senescence. JOURNAL OF PLANT PHYSIOLOGY 2007; 164:1179-87. [PMID: 16987568 DOI: 10.1016/j.jplph.2006.07.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2006] [Accepted: 07/04/2006] [Indexed: 05/11/2023]
Abstract
The effects of short-term darkening and methyl jasmonate (MeJA) on cotyledon senescence were studied 24h after transfer of intact 7-day-old Cucurbita pepo (zucchini) seedlings to darkness or spraying with 100 microM MeJA. The jasmonate inhibitory effect on chlorophyll content and chloroplast transcriptional activity was stronger compared with darkness. Further, MeJA reduced the photosynthetic rate whereas darkness did not affect photosynthesis. Neither stress factor affected the photochemical quantum efficiency of photosystem II (PSII) estimated by the variable fluorescence (F(v))/maximal fluorescence (F(m)) ratio, suggesting the existence of mechanisms protecting the functional activity of PSII at earlier stages of senescence, thus making this parameter more stable compared to others used to quantify senescence. Both stress factors caused a decrease in the content of physiologically active cytokinins, especially trans-zeatin (Z), with the jasmonate effect being much more pronounced when compared to darkness. Our results indicate that MeJA is a more potent inducer of senescence in zucchini cotyledons, at least within the relatively short period of the 24h treatment. This is likely due to its stronger down-regulatory effect on the levels of physiologically active cytokinins.
Collapse
Affiliation(s)
- Kalina Ananieva
- Acad M Popov Institute of Plant Physiology, Acad G Bonchev Str, Bl 21, Sofia, Bulgaria
| | | | | | | | | | | | | |
Collapse
|
19
|
Ren G, An K, Liao Y, Zhou X, Cao Y, Zhao H, Ge X, Kuai B. Identification of a novel chloroplast protein AtNYE1 regulating chlorophyll degradation during leaf senescence in Arabidopsis. PLANT PHYSIOLOGY 2007; 144:1429-41. [PMID: 17468209 PMCID: PMC1914121 DOI: 10.1104/pp.107.100172] [Citation(s) in RCA: 186] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2007] [Accepted: 04/23/2007] [Indexed: 05/15/2023]
Abstract
A dramatic increase of chlorophyll (Chl) degradation occurs during senescence of vegetative plant organs and fruit ripening. Although the biochemical pathway of Chl degradation has long been proposed, little is known about its regulatory mechanism. Identification of Chl degradation-disturbed mutants and subsequently isolation of responsible genes would greatly facilitate the elucidation of the regulation of Chl degradation. Here, we describe a nonyellowing mutant of Arabidopsis (Arabidopsis thaliana), nye1-1, in which 50% Chl was retained, compared to less than 10% in the wild type (Columbia-0), at the end of a 6-d dark incubation. Nevertheless, neither photosynthesis- nor senescence-associated process was significantly affected in nye1-1. Characteristically, a significant reduction in pheophorbide a oxygenase activity was detected in nye1-1. However, no detectable accumulation of either chlorophyllide a or pheophorbide a was observed. Reciprocal crossings revealed that the mutant phenotype was caused by a monogenic semidominant nuclear mutation. We have identified AtNYE1 by positional cloning. Dozens of its putative orthologs, predominantly appearing in higher plant species, were identified, some of which have been associated with Chl degradation in a few crop species. Quantitative polymerase chain reaction analysis showed that AtNYE1 was drastically induced by senescence signals. Constitutive overexpression of AtNYE1 could result in either pale-yellow true leaves or even albino seedlings. These results collectively indicate that NYE1 plays an important regulatory role in Chl degradation during senescence by modulating pheophorbide a oxygenase activity.
Collapse
Affiliation(s)
- Guodong Ren
- State Key Laboratory of Genetic Engineering, Department of Biochemistry, School of Life Sciences, Fudan University, Shanghai, China
| | | | | | | | | | | | | | | |
Collapse
|
20
|
Park SY, Yu JW, Park JS, Li J, Yoo SC, Lee NY, Lee SK, Jeong SW, Seo HS, Koh HJ, Jeon JS, Park YI, Paek NC. The senescence-induced staygreen protein regulates chlorophyll degradation. THE PLANT CELL 2007; 19:1649-64. [PMID: 17513504 PMCID: PMC1913741 DOI: 10.1105/tpc.106.044891] [Citation(s) in RCA: 310] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2006] [Revised: 03/28/2007] [Accepted: 05/02/2007] [Indexed: 05/15/2023]
Abstract
Loss of green color in leaves results from chlorophyll (Chl) degradation in chloroplasts, but little is known about how Chl catabolism is regulated throughout leaf development. Using the staygreen (sgr) mutant in rice (Oryza sativa), which maintains greenness during leaf senescence, we identified Sgr, a senescence-associated gene encoding a novel chloroplast protein. Transgenic rice overexpressing Sgr produces yellowish-brown leaves, and Arabidopsis thaliana pheophorbide a oxygenase-impaired mutants exhibiting a stay-green phenotype during dark-induced senescence have reduced expression of Sgr homologs, indicating that Sgr regulates Chl degradation at the transcriptional level. We show that the leaf stay-greenness of the sgr mutant is associated with a failure in the destabilization of the light-harvesting chlorophyll binding protein (LHCP) complexes of the thylakoid membranes, which is a prerequisite event for the degradation of Chls and LHCPs during senescence. Transient overexpression of Sgr in Nicotiana benthamiana and an in vivo pull-down assay show that Sgr interacts with LHCPII, indicating that the Sgr-LHCPII complexes are formed in the thylakoid membranes. Thus, we propose that in senescing leaves, Sgr regulates Chl degradation by inducing LHCPII disassembly through direct interaction, leading to the degradation of Chls and Chl-free LHCPII by catabolic enzymes and proteases, respectively.
Collapse
Affiliation(s)
- So-Yon Park
- Department of Plant Science and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Korea
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
21
|
Kusaba M, Ito H, Morita R, Iida S, Sato Y, Fujimoto M, Kawasaki S, Tanaka R, Hirochika H, Nishimura M, Tanaka A. Rice NON-YELLOW COLORING1 is involved in light-harvesting complex II and grana degradation during leaf senescence. THE PLANT CELL 2007; 19:1362-75. [PMID: 17416733 PMCID: PMC1913755 DOI: 10.1105/tpc.106.042911] [Citation(s) in RCA: 303] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Chlorophyll degradation is an aspect of leaf senescence, which is an active process to salvage nutrients from old tissues. non-yellow coloring1 (nyc1) is a rice (Oryza sativa) stay-green mutant in which chlorophyll degradation during senescence is impaired. Pigment analysis revealed that degradation of not only chlorophylls but also light-harvesting complex II (LHCII)-bound carotenoids was repressed in nyc1, in which most LHCII isoforms were selectively retained during senescence. Ultrastructural analysis of nyc1 chloroplasts revealed that large and thick grana were present even in the late stage of senescence, suggesting that degradation of LHCII is required for the proper degeneration of thylakoid membranes. Map-based cloning of NYC1 revealed that it encodes a chloroplast-localized short-chain dehydrogenase/reductase (SDR) with three transmembrane domains. The predicted structure of the NYC1 protein and the phenotype of the nyc1 mutant suggest the possibility that NYC1 is a chlorophyll b reductase. Although we were unable to detect the chlorophyll b reductase activity of NYC1, NOL (for NYC1-like), a protein closely related to NYC1 in rice, showed chlorophyll b reductase activity in vitro. We suggest that NYC1 and NOL encode chlorophyll b reductases with divergent functions. Our data collectively suggest that the identified SDR protein NYC1 plays essential roles in the regulation of LHCII and thylakoid membrane degradation during senescence.
Collapse
Affiliation(s)
- Makoto Kusaba
- Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657, Japan.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Zulfugarov IS, Ham OK, Mishra SR, Kim JY, Nath K, Koo HY, Kim HS, Moon YH, An G, Lee CH. Dependence of reaction center-type energy-dependent quenching on photosystem II antenna size. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2007; 1767:773-80. [PMID: 17459330 DOI: 10.1016/j.bbabio.2007.02.021] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2006] [Revised: 02/16/2007] [Accepted: 02/19/2007] [Indexed: 11/22/2022]
Abstract
The effects of photosystem II antenna size on reaction center-type energy-dependent quenching (qE) were examined in rice plants grown under two different light intensities using both wild type and qE-less (OsPsbS knockout) mutant plants. Reaction center-type qE was detected by measuring non-photochemical quenching at 50 micromol photons m(-2) s(-1) white light intensity. We observed that in low light-grown rice plants, reaction center-type qE was higher than in high light-grown plants, and the amount of reaction center-type qE did not depend on zeaxanthin accumulation. This was confirmed in Arabidopsis npq1-2 mutant plants that lack zeaxanthin due to a mutation in the violaxanthin de-epoxidase enzyme. Although the electron transport rate measured at a light intensity of 50 micromol photons m(-2) s(-1) was the same in high light- and low light-grown wild type and mutant plants lacking PsbS protein, the generation of energy-dependent quenching was completely impaired only in mutant plants. Analyses of the pigment content, Lhcb proteins and D1 protein of PSII showed that the antenna size was larger in low light-grown plants, and this correlated with the amount of reaction center-type qE. Our results mark the first time that the reaction center-type qE has been shown to depend on photosystem II antenna size and, although it depends on the existence of PsbS protein, the extent of reaction center-type qE does not correlate with the transcript levels of PsbS protein. The presence of reaction center-type energy-dependent quenching, in addition to antenna-type quenching, in higher plants for dissipation of excess light energy demonstrates the complexity and flexibility of the photosynthetic apparatus of higher plants to respond to different environmental conditions.
Collapse
Affiliation(s)
- Ismayil S Zulfugarov
- Department of Molecular Biology, Pusan National University, Jangjeon-dong, Keumjung-ku, Busan 609-735, South Korea.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Liu Q, Zhu Y, Tao H, Wang N, Wang Y. Damage of PS II during senescence of Spirodela polyrrhiza explants under long-day conditions and its prevention by 6-benzyladenine. JOURNAL OF PLANT RESEARCH 2006; 119:145-52. [PMID: 16474929 DOI: 10.1007/s10265-006-0259-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2005] [Accepted: 12/12/2005] [Indexed: 05/06/2023]
Abstract
The chlorophyll a (Chl a) fluorescence technique was applied to investigate damage of PS II during senescence of excised half-fronds in Spirodela polyrrhiza P143. The green explants showed a typical Chl a fluorescence transient, OJIP. After cultivation of explants under long-day conditions for 8 days, all the J, I, and P steps disappeared, but a clear K band, an indication of senescence, was observed. JIP-test showed that at this time point, the photosynthetic performance index (PI) dropped to zero and the active reaction center (RC) per leaf cross-section (RC/CS) declined to 18%. As the oxygen-evolving complex (OEC) and the chlorophyll content all remained above 42%, it is proposed that the decline in RC contributes more to the appearance of the K band. Supplementation of 6-benzyladenine (6-BA) into the medium at the beginning of cultivation caused dramatic increase in PI, OEC, RC/CS, and chlorophyll content, and at any time before the 8th day reversed the senescence process of the explants. When 6-BA was added after 8 days of cultivation, the PI did not increase anymore, RC/CS and OEC were maintained at 22% and above 40%, respectively, and chlorophyll content decreased continuously further. These data support a view that the decline in RC is crucial for initiation of the irreversible senescence phase of explants cultivated under long-day conditions.
Collapse
Affiliation(s)
- Qingdai Liu
- Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, 300071 Tianjin, China
| | | | | | | | | |
Collapse
|
24
|
Baldisserotto C, Ferroni L, Moro I, Fasulo MP, Pancaldi S. Modulations of the thylakoid system in snow xanthophycean alga cultured in the dark for two months: comparison between microspectrofluorimetric responses and morphological aspects. PROTOPLASMA 2005; 226:125-35. [PMID: 16333571 DOI: 10.1007/s00709-005-0127-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2005] [Accepted: 05/25/2005] [Indexed: 05/05/2023]
Abstract
The response of the plastid was studied, with a special emphasis on thylakoid structure and function, in a snow filamentous xanthophycean alga (Xanthonema sp.) incubated in darkness for two months. Microspectrofluorimetric analyses were performed on single living cells to study the variations in the assembly of the chlorophyll-protein complexes of photosystem II, in comparison with cells grown in light. In parallel, changes in micro- and submicroscopic plastid morphology and in photosynthetic pigment content were monitored. Throughout the experiment, the lamellar architecture of thylakoids in the alga was relatively well preserved, whereas photosystem II underwent disassembly and degradation triggered by prolonged darkness. Conversely, the light-harvesting complex of photosystem II proved to be relatively stable for long periods in darkness. Moreover, a role of the peripheral antennae in determining thylakoid arrangement in xanthophycean algae is implied. Although the responses observed in Xanthonema sp. can be considered in terms of acclimation to darkness, the progressive destabilisation of the light-harvesting complex of photosystem II testifies to incipient ageing of the cells after 35 days.
Collapse
Affiliation(s)
- C Baldisserotto
- Laboratory of Cytophysiology, Department of Natural and Cultural Resources, University of Ferrara, Corso Ercole I d'Este 32, 44100 Ferrara, Italy
| | | | | | | | | |
Collapse
|