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Banh ATM, Thiele B, Chlubek A, Hombach T, Kleist E, Matsubara S. Combination of long-term 13CO 2 labeling and isotopolog profiling allows turnover analysis of photosynthetic pigments in Arabidopsis leaves. PLANT METHODS 2022; 18:114. [PMID: 36183136 PMCID: PMC9526918 DOI: 10.1186/s13007-022-00946-3] [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: 02/28/2022] [Accepted: 09/15/2022] [Indexed: 06/16/2023]
Abstract
BACKGROUND Living cells maintain and adjust structural and functional integrity by continual synthesis and degradation of metabolites and macromolecules. The maintenance and adjustment of thylakoid membrane involve turnover of photosynthetic pigments along with subunits of protein complexes. Quantifying their turnover is essential to understand the mechanisms of homeostasis and long-term acclimation of photosynthetic apparatus. Here we report methods combining whole-plant long-term 13CO2 labeling and liquid chromatography - mass spectrometry (LC-MS) analysis to determine the size of non-labeled population (NLP) of carotenoids and chlorophylls (Chl) in leaf pigment extracts of partially 13C-labeled plants. RESULTS The labeling chamber enabled parallel 13CO2 labeling of up to 15 plants of Arabidopsis thaliana with real-time environmental monitoring ([CO2], light intensity, temperature, relative air humidity and pressure) and recording. No significant difference in growth or photosynthetic pigment composition was found in leaves after 7-d exposure to normal CO2 (~ 400 ppm) or 13CO2 in the labeling chamber, or in ambient air outside the labeling chamber (control). Following chromatographic separation of the pigments and mass peak assignment by high-resolution Fourier-transform ion cyclotron resonance MS, mass spectra of photosynthetic pigments were analyzed by triple quadrupole MS to calculate NLP. The size of NLP remaining after the 7-d 13CO2 labeling was ~ 10.3% and ~ 11.5% for all-trans- and 9-cis-β-carotene, ~ 21.9% for lutein, ~ 18.8% for Chl a and 33.6% for Chl b, highlighting non-uniform turnover of these pigments in thylakoids. Comparable results were obtained in all replicate plants of the 13CO2 labeling experiment except for three that were showing anthocyanin accumulation and growth impairment due to insufficient water supply (leading to stomatal closure and less 13C incorporation). CONCLUSIONS Our methods allow 13CO2 labeling and estimation of NLP for photosynthetic pigments with high reproducibility despite potential variations in [13CO2] between the experiments. The results indicate distinct turnover rates of carotenoids and Chls in thylakoid membrane, which can be investigated in the future by time course experiments. Since 13C enrichment can be measured in a range of compounds, long-term 13CO2 labeling chamber, in combination with appropriate MS methods, facilitates turnover analysis of various metabolites and macromolecules in plants on a time scale of hours to days.
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Affiliation(s)
- Anh Thi-Mai Banh
- IBG-2: Plant Sciences, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Björn Thiele
- IBG-2: Plant Sciences, Forschungszentrum Jülich, 52425, Jülich, Germany
- IBG-3: Agrosphere, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Antonia Chlubek
- IBG-2: Plant Sciences, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Thomas Hombach
- IBG-2: Plant Sciences, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Einhard Kleist
- IBG-2: Plant Sciences, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Shizue Matsubara
- IBG-2: Plant Sciences, Forschungszentrum Jülich, 52425, Jülich, Germany.
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Dhami N, Pogson BJ, Tissue DT, Cazzonelli CI. A foliar pigment-based bioassay for interrogating chloroplast signalling revealed that carotenoid isomerisation regulates chlorophyll abundance. PLANT METHODS 2022; 18:18. [PMID: 35177117 PMCID: PMC8851705 DOI: 10.1186/s13007-022-00847-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 01/18/2022] [Indexed: 06/14/2023]
Abstract
BACKGROUND Some plastid-derived metabolites can control nuclear gene expression, chloroplast biogenesis, and chlorophyll biosynthesis. For example, norflurazon (NFZ) induced inhibition of carotenoid biosynthesis in leaves elicits a protoporphyrin IX (Mg-ProtoIX) retrograde signal that controls chlorophyll biosynthesis and chloroplast development. Carotenoid cleavage products, known as apocarotenoids, also regulate plastid development. The key steps in carotenoid biosynthesis or catabolism that can regulate chlorophyll biosynthesis in leaf tissues remain unclear. Here, we established a foliar pigment-based bioassay using Arabidopsis rosette leaves to investigate plastid signalling processes in young expanding leaves comprising rapidly dividing and expanding cells containing active chloroplast biogenesis. RESULTS We demonstrate that environmental treatments (extended darkness and cold exposure) as well as chemical (norflurazon; NFZ) inhibition of carotenoid biosynthesis, reduce chlorophyll levels in young, but not older leaves of Arabidopsis. Mutants with disrupted xanthophyll accumulation, apocarotenoid phytohormone biosynthesis (abscisic acid and strigolactone), or enzymatic carotenoid cleavage, did not alter chlorophyll levels in young or old leaves. However, perturbations in acyclic cis-carotene biosynthesis revealed that disruption of CAROTENOID ISOMERASE (CRTISO), but not ZETA-CAROTENE ISOMERASE (Z-ISO) activity, reduced chlorophyll levels in young leaves of Arabidopsis plants. NFZ-induced inhibition of PHYTOENE DESATURASE (PDS) activity caused higher phytoene accumulation in younger crtiso leaves compared to WT indicating a continued substrate supply from the methylerythritol 4-phosphate (MEP) pathway. CONCLUSION The Arabidopsis foliar pigment-based bioassay can be used to differentiate signalling events elicited by environmental change, chemical treatment, and/or genetic perturbation, and determine how they control chloroplast biogenesis and chlorophyll biosynthesis. Genetic perturbations that impaired xanthophyll biosynthesis and/or carotenoid catabolism did not affect chlorophyll biosynthesis. The lack of CAROTENOID ISOMERISATION reduced chlorophyll accumulation, but not phytoene biosynthesis in young leaves of Arabidopsis plants growing under a long photoperiod. Findings generated using the newly customised foliar pigment-based bioassay implicate that carotenoid isomerase activity and NFZ-induced inhibition of PDS activity elicit different signalling pathways to control chlorophyll homeostasis in young leaves of Arabidopsis.
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Affiliation(s)
- N Dhami
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
- School of Health and Allied Sciences, Pokhara University, Pokhara 30, Kaski, Gandaki, 33700, Nepal
| | - B J Pogson
- Australian Research Council Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - D T Tissue
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - C I Cazzonelli
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia.
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3
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Koschmieder J, Wüst F, Schaub P, Álvarez D, Trautmann D, Krischke M, Rustenholz C, Mano J, Mueller MJ, Bartels D, Hugueney P, Beyer P, Welsch R. Plant apocarotenoid metabolism utilizes defense mechanisms against reactive carbonyl species and xenobiotics. PLANT PHYSIOLOGY 2021; 185:331-351. [PMID: 33721895 PMCID: PMC8133636 DOI: 10.1093/plphys/kiaa033] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 11/08/2020] [Indexed: 06/12/2023]
Abstract
Carotenoid levels in plant tissues depend on the relative rates of synthesis and degradation of the molecules in the pathway. While plant carotenoid biosynthesis has been extensively characterized, research on carotenoid degradation and catabolism into apocarotenoids is a relatively novel field. To identify apocarotenoid metabolic processes, we characterized the transcriptome of transgenic Arabidopsis (Arabidopsis thaliana) roots accumulating high levels of β-carotene and, consequently, β-apocarotenoids. Transcriptome analysis revealed feedback regulation on carotenogenic gene transcripts suitable for reducing β-carotene levels, suggesting involvement of specific apocarotenoid signaling molecules originating directly from β-carotene degradation or after secondary enzymatic derivatizations. Enzymes implicated in apocarotenoid modification reactions overlapped with detoxification enzymes of xenobiotics and reactive carbonyl species (RCS), while metabolite analysis excluded lipid stress response, a potential secondary effect of carotenoid accumulation. In agreement with structural similarities between RCS and β-apocarotenoids, RCS detoxification enzymes also converted apocarotenoids derived from β-carotene and from xanthophylls into apocarotenols and apocarotenoic acids in vitro. Moreover, glycosylation and glutathionylation-related processes and translocators were induced. In view of similarities to mechanisms found in crocin biosynthesis and cellular deposition in saffron (Crocus sativus), our data suggest apocarotenoid metabolization, derivatization and compartmentalization as key processes in (apo)carotenoid metabolism in plants.
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Affiliation(s)
| | - Florian Wüst
- Faculty of Biology II, University of Freiburg, 79104 Freiburg, Germany
| | - Patrick Schaub
- Faculty of Biology II, University of Freiburg, 79104 Freiburg, Germany
| | - Daniel Álvarez
- Faculty of Biology II, University of Freiburg, 79104 Freiburg, Germany
| | - Danika Trautmann
- Faculty of Biology II, University of Freiburg, 79104 Freiburg, Germany
- Université de Strasbourg, INRAE, SVQV UMR-A 1131, F-68000 Colmar, France
| | - Markus Krischke
- Julius-Maximilians-University Würzburg, Julius-von-Sachs-Institute for Biosciences, Julius-von-Sachs-Platz 2, 97082 Würzburg, Germany
| | - Camille Rustenholz
- Université de Strasbourg, INRAE, SVQV UMR-A 1131, F-68000 Colmar, France
| | - Jun’ichi Mano
- Science Research Center, Organization for Research Initiatives, Yamaguchi University, Yoshida 1677-1, Yamaguchi 753-8515, Japan
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Yoshida 1677-1, Yamaguchi 753-8515, Japan
| | - Martin J Mueller
- Université de Strasbourg, INRAE, SVQV UMR-A 1131, F-68000 Colmar, France
| | - Dorothea Bartels
- Institute of Molecular Physiology and Biotechnology of Plants, University of Bonn, Kirschallee 1, 53115 Bonn, Germany
| | - Philippe Hugueney
- Julius-Maximilians-University Würzburg, Julius-von-Sachs-Institute for Biosciences, Julius-von-Sachs-Platz 2, 97082 Würzburg, Germany
| | - Peter Beyer
- Faculty of Biology II, University of Freiburg, 79104 Freiburg, Germany
| | - Ralf Welsch
- Faculty of Biology II, University of Freiburg, 79104 Freiburg, Germany
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Koschmieder J, Welsch R. Quantification of Carotenoid Pathway Flux in Green and Nongreen Systems. Methods Mol Biol 2021; 2083:279-291. [PMID: 31745929 DOI: 10.1007/978-1-4939-9952-1_21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Metabolite accumulation in plant tissues represents the transient net result of their constant biosynthesis and degradation. For carotenoids, degradation might occur enzymatically by carotenoid cleavage producing plant hormones and volatiles or by nonenzymatic oxidation, both depending on environmental and developmental conditions. Carotenoid biosynthesis is therefore constantly regulated at various levels to attain sufficient carotenoid accumulation, mainly for photosynthesis and photoprotection. Due to the plenitude of carotenoids and their degradation products, it is not feasible to investigate overall carotenoid biosynthetic activity and its regulation by the quantification of all carotenoids including their derivatives. This is an issue encountered in investigations on many other highly branched pathways. We therefore present protocols to determine carotenoid biosynthesis flux in a given plant tissue by HPLC quantification of phytoene, the first pathway-specific intermediate and precursor of all carotenoids synthesized by phytoene synthase (PSY). For this purpose, enzymatic metabolization of phytoene in the tissue under investigation is prevented by treatment with the bleaching herbicide norflurazon, blocking the carotenogenic pathway downstream of PSY. As phytoene is more resistant to oxidation than desaturated carotenoids, the rate of phytoene biosynthesis serves as a good measure for total carotenogenic flux in a given tissue. The method is described for Arabidopsis for two photosynthetically active sample types, namely, seedlings and leaves, as well as for seed-derived callus as nongreen tissue. It should be realizable using only a relatively simple experimental setup and is applicable to other plant tissues as well as to different plant species. Additionally, similar experimental setups could be a useful tool to investigate total flux and turnover rates in other biosynthetic pathways.
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Affiliation(s)
| | - Ralf Welsch
- Institute for Biology II, University of Freiburg, Freiburg, Germany.
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5
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Sun Z, Shen Y, Niinemets Ü. Responses of isoprene emission and photochemical efficiency to severe drought combined with prolonged hot weather in hybrid Populus. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:7364-7381. [PMID: 32996573 PMCID: PMC7906789 DOI: 10.1093/jxb/eraa415] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 09/06/2020] [Indexed: 06/11/2023]
Abstract
Isoprene emissions have been considered as a protective response of plants to heat stress, but there is limited information of how prolonged heat spells affect isoprene emission capacity, particularly under the drought conditions that often accompany hot weather. Under combined long-term stresses, presence of isoprene emission could contribute to the maintenance of the precursor pool for rapid synthesis of essential isoprenoids to repair damaged components of leaf photosynthetic apparatus. We studied changes in leaf isoprene emission rate, photosynthetic characteristics, and antioxidant enzyme activities in two hybrid Populus clones, Nanlin 1388 (relatively high drought tolerance) and Nanlin 895 (relatively high thermotolerance) that were subjected to long-term (30 d) soil water stress (25% versus 90% soil field capacity) combined with a natural heat spell (day-time temperatures of 35-40 °C) that affected both control and water-stressed plants. Unexpectedly, isoprene emissions from both the clones were similar and the overall effects of drought on the emission characteristics were initially minor; however, treatment effects and clonal differences increased with time. In particular, the isoprene emission rate only increased slightly in the Nanlin 895 control plants after 15 d of treatment, whereas it decreased by more than 5-fold in all treatment × clone combinations after 30 d. The reduction in isoprene emission rate was associated with a decrease in the pool size of the isoprene precursor dimethylallyl diphosphate in all cases at 30 d after the start of treatment. Net assimilation rate, stomatal conductance, the openness of PSII centers, and the effective quantum yield all decreased, and non-photochemical quenching and catalase activity increased in both control and water-stressed plants. Contrary to the hypothesis of protection of leaf photosynthetic apparatus by isoprene, the data collectively indicated that prolonged stress affected isoprene emissions more strongly than leaf photosynthetic characteristics. This primarily reflected the depletion of isoprene precursor pools under long-term severe stress.
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Affiliation(s)
- Zhihong Sun
- School of Forestry and Bio-Technology, Zhejiang A&F University, Hangzhou, Zhejiang, China
- Zhejiang A&F University State Key Laboratory of Subtropical Silviculture, Hangzhou, Zhejiang, China
| | - Yan Shen
- School of Forestry and Bio-Technology, Zhejiang A&F University, Hangzhou, Zhejiang, China
| | - Ülo Niinemets
- School of Forestry and Bio-Technology, Zhejiang A&F University, Hangzhou, Zhejiang, China
- Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi, Tartu, Estonia
- Estonian Academy of Sciences, Kohtu, Tallinn, Estonia
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6
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Molecular mechanisms involved in plant photoprotection. Biochem Soc Trans 2018; 46:467-482. [DOI: 10.1042/bst20170307] [Citation(s) in RCA: 110] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Revised: 03/04/2018] [Accepted: 03/05/2018] [Indexed: 11/17/2022]
Abstract
Photosynthesis uses sunlight to convert water and carbon dioxide into biomass and oxygen. When in excess, light can be dangerous for the photosynthetic apparatus because it can cause photo-oxidative damage and decreases the efficiency of photosynthesis because of photoinhibition. Plants have evolved many photoprotective mechanisms in order to face reactive oxygen species production and thus avoid photoinhibition. These mechanisms include quenching of singlet and triplet excited states of chlorophyll, synthesis of antioxidant molecules and enzymes and repair processes for damaged photosystem II and photosystem I reaction centers. This review focuses on the mechanisms involved in photoprotection of chloroplasts through dissipation of energy absorbed in excess.
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7
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Dhami N, Tissue DT, Cazzonelli CI. Leaf-age dependent response of carotenoid accumulation to elevated CO 2 in Arabidopsis. Arch Biochem Biophys 2018; 647:67-75. [PMID: 29604257 DOI: 10.1016/j.abb.2018.03.034] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2017] [Revised: 03/07/2018] [Accepted: 03/26/2018] [Indexed: 01/06/2023]
Abstract
Carotenoids contribute to photosynthesis, photoprotection, phytohormone and apocarotenoid biosynthesis in plants. Carotenoid-derived metabolites control plant growth, development and signalling processes and their accumulation can depend upon changes in the environment. Elevated carbon dioxide (eCO2) often enhances carbon assimilation, early growth patterns and overall plant biomass, and may increase carotenoid accumulation due to higher levels of precursors from isoprenoid biosynthesis. Variable effects of eCO2 on carotenoid accumulation in leaves have been observed for different plant species. Here, we determined whether the variable response of carotenoids to eCO2 was potentially a function of leaf age and the impact of eCO2 on leaf development by growing Arabidopsis in ambient CO2 (400 ppm) and eCO2 (800 ppm). eCO2 increased plant leaf number, rosette area, biomass, seed yield and net photosynthesis. In addition, eCO2 increased carotenoid content by 10-20% in younger emerging leaves, but not in older mature leaves. Older leaves contained approximately 60% less total carotenoids compared to younger leaves. The age-dependent effect on carotenoid content was observed for cotyledon, juvenile and adult phase leaves. We conclude that younger leaves utilize additional carbon from enhanced photosynthesis in eCO2 to increase carotenoid content, yet older leaves have less capacity to store additional carbon into carotenoids.
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Affiliation(s)
- Namraj Dhami
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, 2753, Australia
| | - David T Tissue
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, 2753, Australia
| | - Christopher I Cazzonelli
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, 2753, Australia.
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8
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Liao JC, Hsieh WY, Tseng CC, Hsieh MH. Dysfunctional chloroplasts up-regulate the expression of mitochondrial genes in Arabidopsis seedlings. PHOTOSYNTHESIS RESEARCH 2016; 127:151-9. [PMID: 26008795 DOI: 10.1007/s11120-015-0161-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2014] [Accepted: 05/20/2015] [Indexed: 05/22/2023]
Abstract
Chloroplasts and mitochondria play important roles in maintaining metabolic and energy homeostasis in the plant cell. The interactions between these two organelles, especially photosynthesis and respiration, have been intensively studied. Still, little is known about the regulation of mitochondrial gene expression by chloroplasts and vice versa. The gene expression machineries in chloroplasts and mitochondria rely heavily on the nuclear genome. Thus, the interactions between nucleus and these organelles, including anterograde and retrograde regulation, have been actively investigated in the last two decades. Norflurazon (NF) and lincomycin (Lin) are two commonly used inhibitors to study chloroplast-to-nucleus retrograde signaling in plants. We used NF and Lin to block the development and functions of chloroplasts and examined their effects on mitochondrial gene expression, RNA editing and splicing. The editing of most mitochondrial transcripts was not affected, but the editing extents of nad4-107, nad6-103, and ccmFc-1172 decreased slightly in NF- and Lin-treated seedlings. While the splicing of mitochondrial transcripts was not significantly affected, steady-state mRNA levels of several mitochondrial genes increased significantly in NF- and Lin-treated seedlings. Moreover, Lin seemed to have more profound effects than NF on the expression of mitochondrial genes, indicating that signals derived from these two inhibitors might be distinct. NF and Lin also significantly induced the expression of nuclear genes encoding subunits of mitochondrial electron transport chain complexes. Thus, dysfunctional chloroplasts may coordinately up-regulate the expression of nuclear and mitochondrial genes encoding subunits of respiratory complexes.
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Affiliation(s)
- Jo-Chien Liao
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 11529, Taiwan
| | - Wei-Yu Hsieh
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 11529, Taiwan
| | - Ching-Chih Tseng
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 11529, Taiwan
| | - Ming-Hsiun Hsieh
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 11529, Taiwan.
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Arabidopsis OR proteins are the major posttranscriptional regulators of phytoene synthase in controlling carotenoid biosynthesis. Proc Natl Acad Sci U S A 2015; 112:3558-63. [PMID: 25675505 DOI: 10.1073/pnas.1420831112] [Citation(s) in RCA: 183] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Carotenoids are indispensable natural pigments to plants and humans. Phytoene synthase (PSY), the rate-limiting enzyme in the carotenoid biosynthetic pathway, and ORANGE (OR), a regulator of chromoplast differentiation and enhancer of carotenoid biosynthesis, represent two key proteins that control carotenoid biosynthesis and accumulation in plants. However, little is known about the mechanisms underlying their posttranscriptional regulation. Here we report that PSY and OR family proteins [Arabidopsis thaliana OR (AtOR) and AtOR-like] physically interacted with each other in plastids. We found that alteration of OR expression in Arabidopsis exerted minimal effect on PSY transcript abundance. However, overexpression of AtOR significantly increased the amount of enzymatically active PSY, whereas an ator ator-like double mutant exhibited a dramatically reduced PSY level. The results indicate that the OR proteins serve as the major posttranscriptional regulators of PSY. The ator or ator-like single mutant had little effect on PSY protein levels, which involves a compensatory mechanism and suggests partial functional redundancy. In addition, modification of PSY expression resulted in altered AtOR protein levels, corroborating a mutual regulation of PSY and OR. Carotenoid content showed a correlated change with OR-mediated PSY level, demonstrating the function of OR in controlling carotenoid biosynthesis by regulating PSY. Our findings reveal a novel mechanism by which carotenoid biosynthesis is controlled via posttranscriptional regulation of PSY in plants.
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Rasulov B, Bichele I, Laisk A, Niinemets Ü. Competition between isoprene emission and pigment synthesis during leaf development in aspen. PLANT, CELL & ENVIRONMENT 2014; 37:724-41. [PMID: 24033429 PMCID: PMC4411569 DOI: 10.1111/pce.12190] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Revised: 08/17/2013] [Accepted: 08/20/2013] [Indexed: 05/18/2023]
Abstract
In growing leaves, lack of isoprene synthase (IspS) is considered responsible for delayed isoprene emission, but competition for dimethylallyl diphosphate (DMADP), the substrate for both isoprene synthesis and prenyltransferase reactions in photosynthetic pigment and phytohormone synthesis, can also play a role. We used a kinetic approach based on post-illumination isoprene decay and modelling DMADP consumption to estimate in vivo kinetic characteristics of IspS and prenyltransferase reactions, and to determine the share of DMADP use by different processes through leaf development in Populus tremula. Pigment synthesis rate was also estimated from pigment accumulation data and distribution of DMADP use from isoprene emission changes due to alendronate, a selective inhibitor of prenyltransferases. Development of photosynthetic activity and pigment synthesis occurred with the greatest rate in 1- to 5-day-old leaves when isoprene emission was absent. Isoprene emission commenced on days 5 and 6 and increased simultaneously with slowing down of pigment synthesis. In vivo Michaelis-Menten constant (Km ) values obtained were 265 nmol m(-2) (20 μm) for DMADP-consuming prenyltransferase reactions and 2560 nmol m(-2) (190 μm) for IspS. Thus, despite decelerating pigment synthesis reactions in maturing leaves, isoprene emission in young leaves was limited by both IspS activity and competition for DMADP by prenyltransferase reactions.
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Affiliation(s)
- Bahtijor Rasulov
- Institute of Molecular and Cell Biology, University of Tartu, Riia 23 Tartu 51010, Estonia
| | - Irina Bichele
- Institute of Molecular and Cell Biology, University of Tartu, Riia 23 Tartu 51010, Estonia
| | - Agu Laisk
- Institute of Molecular and Cell Biology, University of Tartu, Riia 23 Tartu 51010, Estonia
| | - Ülo Niinemets
- Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 1, 51014 Tartu, Estonia
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