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Biswal AK, Pattanayak GK, Ruhil K, Kandoi D, Mohanty SS, Leelavati S, Reddy VS, Govindjee G, Tripathy BC. Reduced expression of chlorophyllide a oxygenase (CAO) decreases the metabolic flux for chlorophyll synthesis and downregulates photosynthesis in tobacco plants. PHYSIOLOGY AND MOLECULAR BIOLOGY OF PLANTS : AN INTERNATIONAL JOURNAL OF FUNCTIONAL PLANT BIOLOGY 2024; 30:1-16. [PMID: 38435853 PMCID: PMC10901765 DOI: 10.1007/s12298-023-01395-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 11/17/2023] [Accepted: 11/20/2023] [Indexed: 03/05/2024]
Abstract
Chlorophyll b is synthesized from chlorophyllide a, catalyzed by chlorophyllide a oxygenase (CAO). To examine whether reduced chlorophyll b content regulates chlorophyll (Chl) synthesis and photosynthesis, we raised CAO transgenic tobacco plants with antisense CAO expression, which had lower chlorophyll b content and, thus, higher Chl a/b ratio. Further, these plants had (i) lower chlorophyll b and total Chl content, whether they were grown under low or high light; (ii) decreased steady-state levels of chlorophyll biosynthetic intermediates, due, perhaps, to a feedback-controlled reduction in enzyme expressions/activities; (iii) reduced electron transport rates in their intact leaves, and reduced Photosystem (PS) I, PS II and whole chain electron transport activities in their isolated thylakoids; (iv) decreased carbon assimilation in plants grown under low or high light. We suggest that reduced synthesis of chlorophyll b by antisense expression of CAO, acting at the end of Chl biosynthesis pathway, downregulates the chlorophyll b biosynthesis, resulting in decreased Chl b, total chlorophylls and increased Chl a/b. We have previously shown that the controlled up-regulation of chlorophyll b biosynthesis and decreased Chl a/b ratio by over expression of CAO enhance the rates of electron transport and CO2 assimilation in tobacco. Conversely, our data, presented here, demonstrate that-antisense expression of CAO in tobacco, which decreases Chl b biosynthesis and increases Chl a/b ratio, leads to reduced photosynthetic electron transport and carbon assimilation rates, both under low and high light. We conclude that Chl b modulates photosynthesis; its controlled down regulation/ up regulation decreases/ increases light-harvesting, rates of electron transport, and carbon assimilation. Supplementary Information The online version contains supplementary material available at 10.1007/s12298-023-01395-5.
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Affiliation(s)
- Ajaya K. Biswal
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067 India
| | - Gopal K. Pattanayak
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067 India
| | - Kamal Ruhil
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067 India
| | - Deepika Kandoi
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067 India
- Department of Life Sciences, Sharda University, Greater Noida, UP, India
| | - Sushree S. Mohanty
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067 India
| | - Sadhu Leelavati
- International Center for Genetic Engineering and Biotechnology, New Delhi, 110067 India
| | - Vanga S. Reddy
- International Center for Genetic Engineering and Biotechnology, New Delhi, 110067 India
| | - Govindjee Govindjee
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067 India
- Department of Plant Biology, Department of Biochemistry, and Center of Biophysics & Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801 USA
| | - Baishnab C. Tripathy
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067 India
- Department of Biotechnology, Sharda University, Greater Noida, UP 201310 India
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Huang J, Staes A, Impens F, Demichev V, Van Breusegem F, Gevaert K, Willems P. CysQuant: Simultaneous quantification of cysteine oxidation and protein abundance using data dependent or independent acquisition mass spectrometry. Redox Biol 2023; 67:102908. [PMID: 37793239 PMCID: PMC10562924 DOI: 10.1016/j.redox.2023.102908] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Revised: 09/20/2023] [Accepted: 09/26/2023] [Indexed: 10/06/2023] Open
Abstract
Protein cysteinyl thiols are susceptible to reduction-oxidation reactions that can influence protein function. Accurate quantification of cysteine oxidation is therefore crucial for decoding protein redox regulation. Here, we present CysQuant, a novel approach for simultaneous quantification of cysteine oxidation degrees and protein abundancies. CysQuant involves light/heavy iodoacetamide isotopologues for differential labeling of reduced and reversibly oxidized cysteines analyzed by data-dependent acquisition (DDA) or data-independent acquisition mass spectrometry (DIA-MS). Using plexDIA with in silico predicted spectral libraries, we quantified an average of 18% cysteine oxidation in Arabidopsis thaliana by DIA-MS, including a subset of highly oxidized cysteines forming disulfide bridges in AlphaFold2 predicted structures. Applying CysQuant to Arabidopsis seedlings exposed to excessive light, we successfully quantified the well-established increased reduction of Calvin-Benson cycle enzymes and discovered yet uncharacterized redox-sensitive disulfides in chloroplastic enzymes. Overall, CysQuant is a highly versatile tool for assessing the cysteine modification status that can be widely applied across various mass spectrometry platforms and organisms.
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Affiliation(s)
- Jingjing Huang
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052, Ghent, Belgium; Center for Plant Systems Biology, VIB, 9052, Ghent, Belgium
| | - An Staes
- Department of Biomolecular Medicine, Ghent University, 9052, Ghent, Belgium; Center for Medical Biotechnology, VIB, 9052, Ghent, Belgium; VIB Proteomics Core, 9052, Ghent, Belgium
| | - Francis Impens
- Department of Biomolecular Medicine, Ghent University, 9052, Ghent, Belgium; Center for Medical Biotechnology, VIB, 9052, Ghent, Belgium; VIB Proteomics Core, 9052, Ghent, Belgium
| | - Vadim Demichev
- Department of Biochemistry, Charité - Universitätsmedizin Berlin, 10117, Berlin, Germany
| | - Frank Van Breusegem
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052, Ghent, Belgium; Center for Plant Systems Biology, VIB, 9052, Ghent, Belgium
| | - Kris Gevaert
- Department of Biomolecular Medicine, Ghent University, 9052, Ghent, Belgium; Center for Medical Biotechnology, VIB, 9052, Ghent, Belgium.
| | - Patrick Willems
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052, Ghent, Belgium; Center for Plant Systems Biology, VIB, 9052, Ghent, Belgium; Department of Biomolecular Medicine, Ghent University, 9052, Ghent, Belgium; Center for Medical Biotechnology, VIB, 9052, Ghent, Belgium.
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Effect of the Enhanced Production of Chlorophyll b on the Light Acclimation of Tomato. Int J Mol Sci 2023; 24:ijms24043377. [PMID: 36834789 PMCID: PMC9961381 DOI: 10.3390/ijms24043377] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 01/26/2023] [Accepted: 02/01/2023] [Indexed: 02/11/2023] Open
Abstract
Tomato (Solanum lycopersicum Mill.) is one of the widely cultured vegetables under protected cultivation, in which insufficient light is one of the major factors that limit its growth, yield, and quality. Chlorophyll b (Chl b) is exclusively present in the light-harvesting complex (LHC) of photosystems, while its synthesis is strictly regulated in response to light conditions in order to control the antenna size. Chlorophyllide a oxygenase (CAO) is the sole enzyme that converts Chl a to Chl b for Chl b biosynthesis. Previous studies have shown that overexpressing CAO without the regulating domain (A domain) in Arabidopsis overproduced Chl b. However, the growth characteristics of the Chl b overproduced plants under different light environmental conditions are not well studied. Considering tomatoes are light-loving plants and sensitive to low light stress, this study aimed to uncover the growth character of tomatoes with enhanced production of Chl b. The A domain deleted Arabidopsis CAO fused with the FLAG tag (BCF) was overexpressed in tomatoes. The BCF overexpressed plants accumulated a significantly higher Chl b content, resulting in a significantly lower Chl a/b ratio than WT. Additionally, BCF plants possessed a lower maximal photochemical efficiency of photosystem II (Fv/Fm) and anthocyanin content than WT plants. The growth rate of BCF plants was significantly faster than WT plants under low-light (LL) conditions with light intensity at 50-70 µmol photons m-2 s-1, while BCF plants grew slower than WT plants under high-light (HL) conditions. Our results revealed that Chl b overproduced tomato plants could better adapt to LL conditions by absorbing more light for photosynthesis but adapt poorly to excess light conditions by accumulating more ROS and fewer anthocyanins. Enhanced production of Chl b is able to improve the growth rate of tomatoes that are grown under LL conditions, indicating the prospect of employing Chl b overproduced light-loving crops and ornamental plants for protected or indoor cultivation.
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Research Progress in the Interconversion, Turnover and Degradation of Chlorophyll. Cells 2021; 10:cells10113134. [PMID: 34831365 PMCID: PMC8621299 DOI: 10.3390/cells10113134] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 11/06/2021] [Accepted: 11/08/2021] [Indexed: 01/01/2023] Open
Abstract
Chlorophylls (Chls, Chl a and Chl b) are tetrapyrrole molecules essential for photosynthetic light harvesting and energy transduction in plants. Once formed, Chls are noncovalently bound to photosynthetic proteins on the thylakoid membrane. In contrast, they are dismantled from photosystems in response to environmental changes or developmental processes; thus, they undergo interconversion, turnover, and degradation. In the last twenty years, fruitful research progress has been achieved on these Chl metabolic processes. The discovery of new metabolic pathways has been accompanied by the identification of enzymes associated with biochemical steps. This article reviews recent progress in the analysis of the Chl cycle, turnover and degradation pathways and the involved enzymes. In addition, open questions regarding these pathways that require further investigation are also suggested.
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Identification, Molecular Characteristic, and Expression Analysis of PIFs Related to Chlorophyll Metabolism in Tea Plant ( Camellia sinensis). Int J Mol Sci 2021; 22:ijms222010949. [PMID: 34681609 PMCID: PMC8539375 DOI: 10.3390/ijms222010949] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 10/06/2021] [Accepted: 10/06/2021] [Indexed: 02/01/2023] Open
Abstract
The phytochrome-interacting factors (PIFs) proteins belong to the subfamily of basic helix–loop–helix (bHLH) transcription factors and play important roles in chloroplast development and chlorophyll biosynthesis. Currently, knowledge about the PIF gene family in Camellia sinensis remains very limited. In this study, seven PIF members were identified in the C. sinensis genome and named based on homology with AtPIF genes in Arabidopsis thaliana. All C. sinensis PIF (CsPIF) proteins have both the conserved active PHYB binding (APB) and bHLH domains. Phylogenetic analysis revealed that CsPIFs were clustered into four groups—PIF1, PIF3, PIF7, and PIF8—and most CsPIFs were clustered in pairs with their corresponding orthologs in Populus tremula. CsPIF members in the same group tended to display uniform or similar exon–intron distribution patterns and motif compositions. CsPIF genes were differentially expressed in C. sinensis with various leaf colors and strongly correlated with the expression of genes involved in the chlorophyll metabolism pathway. Promoter analysis of structural genes related to chlorophyll metabolism found DNA-binding sites of PIFs were abundant in the promoter regions. Protein–protein interaction networks of CsPIFs demonstrated a close association with phytochrome, PIF4, HY5, TOC1, COP1, and PTAC12 proteins. Additionally, subcellular localization and transcriptional activity analysis suggested that CsPIF3b was nuclear localized protein and possessed transcriptional activity. We also found that CsPIF3b could activate the transcription of CsHEMA and CsPOR in Nicotiana benthamiana leaves. This work provides comprehensive research of CsPIFs and would be helpful to further promote the regulation mechanism of PIF on chlorophyll metabolism in C. sinensis.
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Pigment modulation in response to irradiance intensity in the fast-growing alga Picochlorum celeri. ALGAL RES 2021. [DOI: 10.1016/j.algal.2021.102370] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Solymosi K, Mysliwa-Kurdziel B. The Role of Membranes and Lipid-Protein Interactions in the Mg-Branch of Tetrapyrrole Biosynthesis. FRONTIERS IN PLANT SCIENCE 2021; 12:663309. [PMID: 33995458 PMCID: PMC8113382 DOI: 10.3389/fpls.2021.663309] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 03/22/2021] [Indexed: 05/31/2023]
Abstract
Chlorophyll (Chl) is essential for photosynthesis and needs to be produced throughout the whole plant life, especially under changing light intensity and stress conditions which may result in the destruction and elimination of these pigments. All steps of the Mg-branch of tetrapyrrole biosynthesis leading to Chl formation are carried out by enzymes associated with plastid membranes. Still the significance of these protein-membrane and protein-lipid interactions in Chl synthesis and chloroplast differentiation are not very well-understood. In this review, we provide an overview on Chl biosynthesis in angiosperms with emphasis on its association with membranes and lipids. Moreover, the last steps of the pathway including the reduction of protochlorophyllide (Pchlide) to chlorophyllide (Chlide), the biosynthesis of the isoprenoid phytyl moiety and the esterification of Chlide are also summarized. The unique biochemical and photophysical properties of the light-dependent NADPH:protochlorophyllide oxidoreductase (LPOR) enzyme catalyzing Pchlide photoreduction and located to peculiar tubuloreticular prolamellar body (PLB) membranes of light-deprived tissues of angiosperms and to envelope membranes, as well as to thylakoids (especially grana margins) are also reviewed. Data about the factors influencing tubuloreticular membrane formation within cells, the spectroscopic properties and the in vitro reconstitution of the native LPOR enzyme complexes are also critically discussed.
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Affiliation(s)
- Katalin Solymosi
- Department of Plant Anatomy, ELTE Eötvös Loránd University, Budapest, Hungary
| | - Beata Mysliwa-Kurdziel
- Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
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Sheng Z, Lv Y, Li W, Luo R, Wei X, Xie L, Jiao G, Shao G, Wang J, Tang S, Hu P. Yellow-Leaf 1 encodes a magnesium-protoporphyrin IX monomethyl ester cyclase, involved in chlorophyll biosynthesis in rice (Oryza sativa L.). PLoS One 2017; 12:e0177989. [PMID: 28558018 PMCID: PMC5448749 DOI: 10.1371/journal.pone.0177989] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 05/06/2017] [Indexed: 01/09/2023] Open
Abstract
Magnesium-protoporphyrin IX monomethyl ester cyclase (MPEC) catalyzes the conversion of MPME to divinyl protochlorophyllide (DVpchlide). This is an essential enzyme during chlorophyll (Chl) biosynthesis but details of its function in rice are still lacking. Here, we identified a novel rice mutant yellow-leaf 1 (yl-1), which showed decreased Chl accumulation, abnormal chloroplast ultrastructure and attenuated photosynthetic activity. Map-based cloning and over-expression analysis suggested that YL-1 encodes a subunit of MPEC. The YL-1 protein localizes in chloroplasts, and it is mainly expressed in green tissues, with greatest abundance in leaves and young panicles. Results of qRT-PCR showed that Chl biosynthesis upstream genes were highly expressed in the yl-1 mutant, while downstream genes were compromised, indicating that YL-1 plays a pivotal role in the Chl biosynthesis. Furthermore, the expression levels of photosynthesis and chloroplast development genes were also affected. RNA-seq results futher proved that numerous membrane-associated genes, including many plastid membrane-associated genes, have altered expression pattern in the yl-1 mutant, implying that YL-1 is required for plastid membrane stability. Thus, our study confirms a putative MPME cyclase as a novel key enzyme essential for Chl biosynthesis and chloroplast membrane stability in rice.
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Affiliation(s)
- Zhonghua Sheng
- State Key Laboratory of Rice Biology, Key Laboratory of Rice Biology and Breeding of Ministry of Agriculture, China National Rice Research Institute, Hangzhou, China
| | - Yusong Lv
- State Key Laboratory of Rice Biology, Key Laboratory of Rice Biology and Breeding of Ministry of Agriculture, China National Rice Research Institute, Hangzhou, China
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
| | - Wei Li
- Agricultural College of Hunan Agricultural University, Changsha, China
| | - Rongjian Luo
- State Key Laboratory of Rice Biology, Key Laboratory of Rice Biology and Breeding of Ministry of Agriculture, China National Rice Research Institute, Hangzhou, China
| | - Xiangjin Wei
- State Key Laboratory of Rice Biology, Key Laboratory of Rice Biology and Breeding of Ministry of Agriculture, China National Rice Research Institute, Hangzhou, China
| | - Lihong Xie
- State Key Laboratory of Rice Biology, Key Laboratory of Rice Biology and Breeding of Ministry of Agriculture, China National Rice Research Institute, Hangzhou, China
| | - Guiai Jiao
- State Key Laboratory of Rice Biology, Key Laboratory of Rice Biology and Breeding of Ministry of Agriculture, China National Rice Research Institute, Hangzhou, China
| | - Gaoneng Shao
- State Key Laboratory of Rice Biology, Key Laboratory of Rice Biology and Breeding of Ministry of Agriculture, China National Rice Research Institute, Hangzhou, China
| | - Jianlong Wang
- Agricultural College of Hunan Agricultural University, Changsha, China
| | - Shaoqing Tang
- State Key Laboratory of Rice Biology, Key Laboratory of Rice Biology and Breeding of Ministry of Agriculture, China National Rice Research Institute, Hangzhou, China
- * E-mail: (PH); (ST)
| | - Peisong Hu
- State Key Laboratory of Rice Biology, Key Laboratory of Rice Biology and Breeding of Ministry of Agriculture, China National Rice Research Institute, Hangzhou, China
- * E-mail: (PH); (ST)
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Xue X, Wang Q, Qu Y, Wu H, Dong F, Cao H, Wang HL, Xiao J, Shen Y, Wan Y. Development of the photosynthetic apparatus of Cunninghamia lanceolata in light and darkness. THE NEW PHYTOLOGIST 2017; 213:300-313. [PMID: 27401059 DOI: 10.1111/nph.14096] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 06/05/2016] [Indexed: 05/27/2023]
Abstract
Here, we compared the development of dark- and light-grown Chinese fir (Cunninghamia lanceolata) cotyledons, which synthesize chlorophyll in the dark, representing a different phenomenon from angiosperm model plants. We determined that the grana lamellar membranes were well developed in both chloroplasts and etiochloroplasts. The accumulation of thylakoid membrane protein complexes was similar between chloroplasts and etiochloroplasts. Measurement of chlorophyll fluorescence parameters indicated that photosystem II (PSII) had low photosynthetic activities, whereas the photosystem I (PSI)-driven cyclic electron flow (CEF) rate exceeded the rate of PSII-mediated photon harvesting in etiochloroplasts. Analysis of the protein contents in etiochloroplasts indicated that the light-harvesting complex II remained mostly in its monomeric conformation. The ferredoxin NADP+ oxidoreductase and NADH dehydrogenase-like complexes were relatively abundantly expressed in etiochloroplasts for Chinese fir. Our transcriptome analysis contributes a global expression database for Chinese fir cotyledons, providing background information on the regulatory mechanisms of different genes involved in the development of dark- and light-grown cotyledons. In conclusion, we provide a novel description of the early developmental status of the light-dependent and light-independent photosynthetic apparatuses in gymnosperms.
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Affiliation(s)
- Xian Xue
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083, China
- College of Agriculture, Henan University of Science and Technology, Luoyang, 471003, China
| | - Qi Wang
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083, China
| | - Yanli Qu
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083, China
| | - Hongyang Wu
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083, China
| | - Fengqin Dong
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Haoyan Cao
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083, China
| | - Hou-Ling Wang
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083, China
| | - Jianwei Xiao
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083, China
| | - Yingbai Shen
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083, China
| | - Yinglang Wan
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083, China
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Zhu X, Guo S, Wang Z, Du Q, Xing Y, Zhang T, Shen W, Sang X, Ling Y, He G. Map-based cloning and functional analysis of YGL8, which controls leaf colour in rice (Oryza sativa). BMC PLANT BIOLOGY 2016; 16:134. [PMID: 27297403 PMCID: PMC4907030 DOI: 10.1186/s12870-016-0821-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2015] [Accepted: 05/25/2016] [Indexed: 05/22/2023]
Abstract
BACKGROUND As the indispensable part of plant, leaf blade mainly functions as the production workshops where organic substance is produced by photosynthesis. Leaf colour mutation is a genetic phenomenon that has a high frequency and is easily identified. The mutations always exhibit negative impact on the development of plants in any of the different stages of growth. Up to now, numerous genes involved in leaf colour mutations have been cloned. RESULTS In this study, a yellow-green leaf mutant, yellow-green leaf 8 (ygl8), with stable genetic phenotype, has been screened out in the progeny of an excellent indica restorer line Jinhui 10 with seeds treated by EMS. The levels of Chl a, Chl b and total chlorophyll were significantly lower in ygl8 than those in the WT throughout the whole growth period, while no clear change was noted in the Chl a/b ratio. Transmission electron microscopy demonstrated that the lamellae were clearly intumescent and intricately stacked in ygl8. Furthermore, compared with those of the WT, the stomatal conductance, intercellular CO2 concentration, photosynthetic rate and transpiration rate of ylg8 were all significantly lower. Map-based cloning results showed that Loc_Os01g73450, encoding a chloroplast-targeted UMP kinase, corresponded to Ygl8 and played an important role in regulating leaf colour in rice (Oryza sativa). Complementation of ygl8 with the WT DNA sequence of Loc_Os01g73450 led to restoration of the normal phenotype, and transgenic RNA interference plants showed a yellow-green colour. Analysis of the spatial and temporal expression of Ygl8 indicated that it was highly expressed in leaf blades and weakly expressed in other tissues. qRT-PCR also showed that the expression levels of the major Photosystem I core subunits plastome-encoded PsaA, PsaB and PsbC were significantly reduced in ygl8. The expression levels of nuclear-encoded gene involved in Chl biosynthesis HEMC, HEME, and PORA were also decreased when compared with the wild-type. CONCLUSIONS Independent of Chl biosynthesis and photosystem, YGL8 may affect the structure and function of chloroplasts grana lamellae by regulating plastid genome encoded thylakoid membrane constitutive gene expression and indirectly influences Chl biosynthesis.
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Affiliation(s)
- Xiaoyan Zhu
- Key Laboratory of Application and Safety Control of Genetically Modified Crops, Rice Research Institute of Southwest University, Chongqing, 400716, China
| | - Shuang Guo
- Key Laboratory of Application and Safety Control of Genetically Modified Crops, Rice Research Institute of Southwest University, Chongqing, 400716, China
- Institute of Rice, Chongqing Academy of Agricultural Sciences, Chongqing, 401329, China
| | - Zhongwei Wang
- Key Laboratory of Application and Safety Control of Genetically Modified Crops, Rice Research Institute of Southwest University, Chongqing, 400716, China
| | - Qing Du
- Key Laboratory of Application and Safety Control of Genetically Modified Crops, Rice Research Institute of Southwest University, Chongqing, 400716, China
- Forestry Bureau of Chuanshan District, Suining, Sichuan, 629000, China
| | - Yadi Xing
- Key Laboratory of Application and Safety Control of Genetically Modified Crops, Rice Research Institute of Southwest University, Chongqing, 400716, China
| | - Tianquan Zhang
- Key Laboratory of Application and Safety Control of Genetically Modified Crops, Rice Research Institute of Southwest University, Chongqing, 400716, China
| | - Wenqiang Shen
- Key Laboratory of Application and Safety Control of Genetically Modified Crops, Rice Research Institute of Southwest University, Chongqing, 400716, China
| | - Xianchun Sang
- Key Laboratory of Application and Safety Control of Genetically Modified Crops, Rice Research Institute of Southwest University, Chongqing, 400716, China
| | - Yinghua Ling
- Key Laboratory of Application and Safety Control of Genetically Modified Crops, Rice Research Institute of Southwest University, Chongqing, 400716, China
| | - Guanghua He
- Key Laboratory of Application and Safety Control of Genetically Modified Crops, Rice Research Institute of Southwest University, Chongqing, 400716, China.
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Turan S, Tripathy BC. Salt-stress induced modulation of chlorophyll biosynthesis during de-etiolation of rice seedlings. PHYSIOLOGIA PLANTARUM 2015; 153:477-91. [PMID: 25132047 DOI: 10.1111/ppl.12250] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 05/19/2014] [Indexed: 05/08/2023]
Abstract
Chlorophyll biosynthesis in plants is subjected to modulation by various environmental factors. To understand the modulation of the chlorophyll (Chl) biosynthesis during greening process by salt, 100-200 mM NaCl was applied to the roots of etiolated rice seedlings 12 h prior to the transfer to light. Application of 200 mM NaCl to rice seedlings that were grown in light for further 72 h resulted in reduced dry matter production (-58%) and Chl accumulation (-66%). Ionic imbalance due to salinity stress resulted in additional downregulation (41-45%) of seedling dry weight, Chl and carotenoid contents over and above that of similar osmotic stress induced by polyethylene glycol. Downregulation of Chl biosynthesis may be attributed to decreased activities of Chl biosynthetic pathway enzymes, i.e. 5-aminolevulinic acid (ALA) dehydratase (EC-2.4.1.24), porphobilinogen deaminase (EC-4.3.1.8), coproporphyrinogen III oxidase (EC-1.3.3.3), protoporphyrinogen IX oxidase (EC-1.3.3.4), Mg-protoporphyrin IX chelatase (EC-6.6.1.1) and protochlorophyllide oxidoreductase (EC-1.3.33.1). Reduced enzymatic activities were due to downregulation of their protein abundance and/or gene expression in salt-stressed seedlings. The extent of downregulation of ALA biosynthesis nearly matched with that of protochlorophyllide and Chl to prevent the accumulation of highly photosensitive photodynamic tetrapyrroles that generates singlet oxygen under stress conditions. Although, ALA synthesis decreased, the gene/protein expression of glutamyl-tRNA reductase (EC-1.2.1.70) increased suggesting it may play a role in acclimation to salt stress. The similar downregulation of both early and late Chl biosynthesis intermediates in salt-stressed seedlings suggests a regulatory network of genes involved in tetrapyrrole biosynthesis.
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Affiliation(s)
- Satpal Turan
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
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Domaschke S, Vivas M, Sancho LG, Printzen C. Ecophysiology and genetic structure of polar versus temperate populations of the lichen Cetraria aculeata. Oecologia 2013; 173:699-709. [PMID: 23649754 DOI: 10.1007/s00442-013-2670-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Accepted: 04/17/2013] [Indexed: 02/07/2023]
Abstract
We studied polar and temperate samples of the lichen Cetraria aculeata to investigate whether genetical differences between photobionts are correlated with physiological properties of the lichen holobiont. Net photosynthesis and dark respiration (DR) at different temperatures (from 0 to 30 °C) and photon flux densities (from 0 to 1,200 μmol m(-2) s(-1)) were studied for four populations of Cetraria aculeata. Samples were collected from maritime Antarctica, Svalbard, Germany and Spain, representing different climatic situations. Sequencing of the photobiont showed that the investigated samples fall in the polar and temperate clade described in Fernández-Mendoza et al. (Mol Ecol 20:1208-1232, 2011). Lichens with photobionts from these clades differ in their temperature optimum for photosynthesis, maximal net photosynthesis, maximal DR and chlorophyll content. Maximal net photosynthesis was much lower in Antarctica and Svalbard than in Germany and Spain. The difference was smaller when rates were expressed by chlorophyll content. The same is true for the temperature optima of polar (11 °C) and temperate (15 and 17 °C) lichens. Our results indicate that lichen mycobionts may adapt or acclimate to local environmental conditions either by selecting algae from regional pools or by regulating algal cell numbers (chlorophyll content) within the thallus.
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Affiliation(s)
- S Domaschke
- Department of Botany and Molecular Evolution, Senckenberg Research Institute, Senckenberganlage 25, 60325, Frankfurt am Main, Germany,
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Biswal AK, Pattanayak GK, Pandey SS, Leelavathi S, Reddy VS, Govindjee, Tripathy BC. Light intensity-dependent modulation of chlorophyll b biosynthesis and photosynthesis by overexpression of chlorophyllide a oxygenase in tobacco. PLANT PHYSIOLOGY 2012; 159:433-49. [PMID: 22419827 PMCID: PMC3375976 DOI: 10.1104/pp.112.195859] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Accepted: 03/13/2012] [Indexed: 05/19/2023]
Abstract
Chlorophyll b is synthesized by the oxidation of a methyl group on the B ring of a tetrapyrrole molecule to a formyl group by chlorophyllide a oxygenase (CAO). The full-length CAO from Arabidopsis (Arabidopsis thaliana) was overexpressed in tobacco (Nicotiana tabacum) that grows well at light intensities much higher than those tolerated by Arabidopsis. This resulted in an increased synthesis of glutamate semialdehyde, 5-aminolevulinic acid, magnesium-porphyrins, and chlorophylls. Overexpression of CAO resulted in increased chlorophyll b synthesis and a decreased chlorophyll a/b ratio in low light-grown as well as high light-grown tobacco plants; this effect, however, was more pronounced in high light. The increased potential of the protochlorophyllide oxidoreductase activity and chlorophyll biosynthesis compensated for the usual loss of chlorophylls in high light. Increased chlorophyll b synthesis in CAO-overexpressed plants was accompanied not only by an increased abundance of light-harvesting chlorophyll proteins but also of other proteins of the electron transport chain, which led to an increase in the capture of light as well as enhanced (40%-80%) electron transport rates of photosystems I and II at both limiting and saturating light intensities. Although the quantum yield of carbon dioxide fixation remained unchanged, the light-saturated photosynthetic carbon assimilation, starch content, and dry matter accumulation increased in CAO-overexpressed plants grown in both low- and high-light regimes. These results demonstrate that controlled up-regulation of chlorophyll b biosynthesis comodulates the expression of several thylakoid membrane proteins that increase both the antenna size and the electron transport rates and enhance carbon dioxide assimilation, starch content, and dry matter accumulation.
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Affiliation(s)
| | | | - Shiv S. Pandey
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India (A.K.B., G.K.P., S.S.P., G., B.C.T.); International Center for Genetic Engineering and Biotechnology, New Delhi 110067, India (S.L., V.S.R.); and Department of Plant Biology, Department of Biochemistry and Center of Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (G.)
| | - Sadhu Leelavathi
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India (A.K.B., G.K.P., S.S.P., G., B.C.T.); International Center for Genetic Engineering and Biotechnology, New Delhi 110067, India (S.L., V.S.R.); and Department of Plant Biology, Department of Biochemistry and Center of Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (G.)
| | - Vanga S. Reddy
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India (A.K.B., G.K.P., S.S.P., G., B.C.T.); International Center for Genetic Engineering and Biotechnology, New Delhi 110067, India (S.L., V.S.R.); and Department of Plant Biology, Department of Biochemistry and Center of Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (G.)
| | - Govindjee
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India (A.K.B., G.K.P., S.S.P., G., B.C.T.); International Center for Genetic Engineering and Biotechnology, New Delhi 110067, India (S.L., V.S.R.); and Department of Plant Biology, Department of Biochemistry and Center of Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (G.)
| | - Baishnab C. Tripathy
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India (A.K.B., G.K.P., S.S.P., G., B.C.T.); International Center for Genetic Engineering and Biotechnology, New Delhi 110067, India (S.L., V.S.R.); and Department of Plant Biology, Department of Biochemistry and Center of Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (G.)
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Sakuraba Y, Yokono M, Akimoto S, Tanaka R, Tanaka A. Deregulated chlorophyll b synthesis reduces the energy transfer rate between photosynthetic pigments and induces photodamage in Arabidopsis thaliana. PLANT & CELL PHYSIOLOGY 2010; 51:1055-65. [PMID: 20403808 DOI: 10.1093/pcp/pcq050] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Chl b is one of the major light-harvesting pigments in land plants. The synthesis of Chl b is strictly regulated in response to light conditions in order to control the antenna size of photosystems. Regulation of Chl b also affects its distribution as it occurs preferentially in the peripheral antenna complexes. However, it has not been experimentally shown how plants respond to environmental conditions when they accumulate excess Chl b. Previously, we produced an Arabidopsis transgenic plant (referred to as the BC plant) in which Chl b biosynthesis was enhanced. In this study, we analyzed the photosynthetic properties and genome-wide gene expression in this plant under high light conditions in order to understand the effects of deregulated Chl b biosynthesis. The energy transfer rates between Chl a molecules in PSII decreased and H(2)O(2) accumulated extensively in the BC plant. Microarray analysis revealed that a group of genes involved in anthocyanin biosynthesis was down-regulated and that another group of genes, reported to be sensitive to H(2)O(2), was up-regulated in the BC plant. We also found that anthocyanin levels were low, which was consistent with the results of the microarray analysis. These results indicate that deregulation of Chl b caused severe photodamage and altered gene expression profiles under strong illumination. The importance of the regulation of Chl b synthesis is discussed in relation to the correct localization of Chl b and gene expression.
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Affiliation(s)
- Yasuhito Sakuraba
- Institute of Low Temperature Science, Hokkaido University, N19 W8, Kita-ku, Sapporo, 060-0819 Japan
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Nagane T, Tanaka A, Tanaka R. Involvement of AtNAP1 in the regulation of chlorophyll degradation in Arabidopsis thaliana. PLANTA 2010; 231:939-49. [PMID: 20087600 DOI: 10.1007/s00425-010-1099-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Accepted: 01/06/2010] [Indexed: 05/08/2023]
Abstract
In plants, chlorophyll is actively synthesized from glutamate in the developmental phase and is degraded into non-fluorescent chlorophyll catabolites during senescence. The chlorophyll metabolism must be strictly regulated because chlorophylls and their intermediate molecules generate reactive oxygen species. Many mechanisms have been proposed for the regulation of chlorophyll synthesis including gene expression, protein stability, and feedback inhibition. However, information on the regulation of chlorophyll degradation is limited. The conversion of chlorophyll b to chlorophyll a is the first step of chlorophyll degradation. In order to understand the regulatory mechanism of this reaction, we isolated a mutant which accumulates 7-hydroxymethyl chlorophyll a (HMChl), an intermediate molecule of chlorophyll b to chlorophyll a conversion, and designated the mutant hmc1. In addition to HMChl, hmc1 accumulated pheophorbide a, a chlorophyll degradation product, when chlorophyll degradation was induced by dark incubation. These results indicate that the activities of HMChl reductase (HAR) and pheophorbide a oxygenase (PaO) are simultaneously down-regulated in this mutant. We identified a mutation in the AtNAP1 gene, which encodes a subunit of the complex for iron-sulfur cluster formation. HAR and PaO use ferredoxin as a reducing power and PaO has an iron-sulfur center; however, there were no distinct differences in the protein levels of ferredoxin and PaO between wild type and hmc1. The concerted regulation of chlorophyll degradation is discussed in relation to the function of AtNAP1.
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Affiliation(s)
- Tomohiro Nagane
- Institute of Low Temperature Science, Hokkaido University, N19W8, Kita-ku, Sapporo 060-0819, Japan
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Evans IM, Rus AM, Belanger EM, Kimoto M, Brusslan JA. Dismantling of Arabidopsis thaliana mesophyll cell chloroplasts during natural leaf senescence. PLANT BIOLOGY (STUTTGART, GERMANY) 2010; 12:1-12. [PMID: 20653883 PMCID: PMC4383266 DOI: 10.1111/j.1438-8677.2009.00206.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
One of the earliest events in the process of leaf senescence is dismantling of chloroplasts. Mesophyll cell chloroplasts from rosette leaves were studied in Arabidopsis thaliana undergoing natural senescence. The number of chloroplasts decreased by only 17% in fully yellow leaves, and chloroplasts were found to undergo progressive photosynthetic and ultrastructural changes as senescence proceeded. In ultrastructural studies, an intact tonoplast could not be visualized, thus, a 35S-GFP::delta-TIP line with a GFP-labeled tonoplast was used to demonstrate that chloroplasts remain outside of the tonoplast even at late stages of senescence. Chloroplast DNA was measured by real-time PCR at four different chloroplast loci, and a fourfold decrease in chloroplast DNA per chloroplast was noted in yellow senescent leaves when compared to green leaves from plants of the same age. Although chloroplast DNA did decrease, the chloroplast/nuclear gene copy ratio was still 31:1 in yellow leaves. Interestingly, mRNA levels for the four loci differed: psbA and ndhB mRNAs remained abundant late into senescence, while rpoC1 and rbcL mRNAs decreased in parallel to chloroplast DNA. Together, these data demonstrate that, during senescence, chloroplasts remain outside of the vacuole as distinct organelles while the thylakoid membranes are dismantled internally. As thylakoids were dismantled, Rubisco large subunit, Lhcb1, and chloroplast DNA levels declined, but variable levels of mRNA persisted.
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Affiliation(s)
- I M Evans
- Department of Genetics, Yale University School of Medicine, New Haven, CT, USA
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Sakuraba Y, Tanaka R, Yamasato A, Tanaka A. Determination of a chloroplast degron in the regulatory domain of chlorophyllide a oxygenase. J Biol Chem 2009; 284:36689-36699. [PMID: 19843523 DOI: 10.1074/jbc.m109.008144] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Chlorophyll b is one of the major photosynthetic pigments of plants. The regulation of chlorophyll b biosynthesis is important for plants in order to acclimate to changing environmental conditions. In the chloroplast, chlorophyll b is synthesized from chlorophyll a by chlorophyllide a oxygenase (CAO), a Rieske-type monooxygenase. The activity of this enzyme is regulated at the level of protein stability via a feedback mechanism through chlorophyll b. The Clp protease and the N-terminal domain (designated the A domain) of CAO are essential for the regulatory mechanism. In this study, we aimed to identify the specific amino acid residue or the sequence within the A domain that is essential for this regulation. To accomplish this goal, we randomly introduced base substitutions into the A domain and searched for potentially important residues by analyzing 1,000 transformants of Arabidopsis thaliana. However, none of the single amino acid substitutions significantly stabilized CAO. Therefore, we generated serial deletions in the A domain and expressed these deletions in the background of CAO-deficient Arabidopsis mutant. We found that the amino acid sequence (97)QDLLTIMILH(106) is essential for the regulation of the protein stability. We furthermore determined that this sequence induces the destabilization of green fluorescent protein. These results suggest that this sequence serves as a degradation signal that is recognized by proteases functioning in the chloroplast.
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Affiliation(s)
- Yasuhito Sakuraba
- Institute of Low Temperature Science, Hokkaido University, N19 W8 Kita-Ku, Sapporo 060-0819, Japan.
| | - Ryouichi Tanaka
- Institute of Low Temperature Science, Hokkaido University, N19 W8 Kita-Ku, Sapporo 060-0819, Japan
| | - Akihiro Yamasato
- Research Institute for Biological Sciences Okayama, Okayama 716-1241, Japan
| | - Ayumi Tanaka
- Institute of Low Temperature Science, Hokkaido University, N19 W8 Kita-Ku, Sapporo 060-0819, Japan
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Hu W, Su YS, Lagarias JC. A light-independent allele of phytochrome B faithfully recapitulates photomorphogenic transcriptional networks. MOLECULAR PLANT 2009; 2:166-82. [PMID: 19529817 PMCID: PMC2639728 DOI: 10.1093/mp/ssn086] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2008] [Accepted: 11/08/2008] [Indexed: 05/20/2023]
Abstract
Dominant gain-of-function alleles of Arabidopsis phytochrome B were recently shown to confer light-independent, constitutive photomorphogenic (cop) phenotypes to transgenic plants (Su and Lagarias, 2007). In the present study, comparative transcription profiling experiments were performed to assess whether the pattern of gene expression regulated by these alleles accurately reflects the process of photomorphogenesis in wild-type Arabidopsis. Whole-genome transcription profiles of dark-grown phyAphyB seedlings expressing the Y276H mutant of phyB (YHB) revealed that YHB reprograms about 13% of the Arabidopsis transcriptome in a light-independent manner. The YHB-regulated transcriptome proved qualitatively similar to but quantitatively greater than those of wild-type seedlings grown under 15 or 50 micromol m(-2) m(-1) continuous red light (Rc). Among the 2977 genes statistically significant two-fold (SSTF) regulated by YHB in the absence of light include those encoding components of the photosynthetic apparatus, tetrapyrrole/pigment biosynthetic pathways, and early light-responsive signaling factors. Approximately 80% of genes SSTF regulated by Rc were also YHB-regulated. Expression of a notable subset of 346 YHB-regulated genes proved to be strongly attenuated by Rc, indicating compensating regulation by phyC-E and/or other Rc-dependent processes. Since the majority of these 346 genes are regulated by the circadian clock, these results suggest that phyA- and phyB-independent light signaling pathway(s) strongly influence clock output. Together with the unique plastid morphology of dark-grown YHB seedlings, these analyses indicate that the YHB mutant induces constitutive photomorphogenesis via faithful reconstruction of phyB signaling pathways in a light-independent fashion.
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Affiliation(s)
- Wei Hu
- Department of Molecular and Cellular Biology, College of Biological Sciences, University of California, Davis, CA 95616, USA
| | - Yi-Shin Su
- Department of Molecular and Cellular Biology, College of Biological Sciences, University of California, Davis, CA 95616, USA
- Present address: Carnegie Institution of Washington, Department of Plant Biology, Stanford, CA 94305, USA
| | - J. Clark Lagarias
- Department of Molecular and Cellular Biology, College of Biological Sciences, University of California, Davis, CA 95616, USA
- To whom correspondence should be addressed. E-mail , fax +1-530-752-3085
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Kwak JM, Mäser P, Schroeder JI. The Clickable Guard Cell, Version II: Interactive Model of Guard Cell Signal Transduction Mechanisms and Pathways. THE ARABIDOPSIS BOOK 2008; 6:e0114. [PMID: 22303239 PMCID: PMC3243356 DOI: 10.1199/tab.0114] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Guard cells are located in the leaf epidermis and pairs of guard cells surround and form stomatal pores, which regulate CO(2) influx from the atmosphere into leaves for photosynthetic carbon fixation. Stomatal guard cells also regulate water loss of plants via transpiration to the atmosphere. Signal transduction mechanisms in guard cells integrate a multitude of different stimuli to modulate stomatal apertures. Stomata open in response to light. Stomata close in response to drought stress, elevated CO(2), ozone and low humidity. In response to drought, plants synthesize the hormone abscisic acid (ABA) that triggers closing of stomatal pores. Guard cells have become a highly developed model system for dissecting signal transduction mechanisms in plants and for elucidating how individual signaling mechanisms can interact within a network in a single cell. Many new findings have been made in the last few years. This chapter is an update of an electronic interactive chapter in the previous edition of The Arabidopsis Book (Mäser et al. 2003). Here we focus on mechanisms for which genes and mutations have been characterized, including signaling components for which there is substantial signaling, biochemical and genetic evidence. Ion channels have been shown to represent targets of early signal transduction mechanisms and provide functional signaling and quantitative analysis points to determine where and how mutations affect branches within the guard cell signaling network. Although a substantial number of genes and proteins that function in guard cell signaling have been identified in recent years, there are many more left to be identified and the protein-protein interactions within this network will be an important subject of future research. A fully interactive clickable electronic version of this publication can be accessed at the following web site: http://www-biology.ucsd.edu/labs/schroeder/clickablegc2/. The interactive clickable version includes the following features: Figure 1. Model for the roles of ion channels in ABA signaling.Figure 2. Blue light signaling pathways in guard cells.Figure 3. ABA signaling pathways in guard cells.Figure 1 is linked to explanations that appear upon mouse-over. Figure 2 and Figure 3 are clickable and linked to info boxes, which in turn are linked to TAIR, to relevant abstracts in PubMed, and to updated background explanations from Schroeder et al (2001), used with permission of Annual Reviews of Plant Biology.
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Affiliation(s)
- June M. Kwak
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742
| | - Pascal Mäser
- Institute of Cell Biology, University of Berne, CH-3012 Bern, Switzerland
| | - Julian I. Schroeder
- Division of Biological Sciences, Cell and Developmental Biology Section and Center for Molecular Genetics, University of California, San Diego, La Jolla, California 92093-0116
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Masuda T, Fujita Y. Regulation and evolution of chlorophyll metabolism. Photochem Photobiol Sci 2008; 7:1131-49. [PMID: 18846277 DOI: 10.1039/b807210h] [Citation(s) in RCA: 146] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Chlorophylls are the most abundant tetrapyrrole molecules essential for photosynthesis in photosynthetic organisms. After many years of intensive research, most of the genes encoding the enzymes for the pathway have been identified, and recently the underlying molecular mechanisms have been elucidated. These studies revealed that the regulation of chlorophyll metabolism includes all levels of control to allow a balanced metabolic flow in response to external and endogenous factors and to ensure adaptation to varying needs of chlorophyll during plant development. Furthermore, identification of biosynthetic genes from various organisms and genetic analysis of functions of identified genes enables us to predict the evolutionary scenario of chlorophyll metabolism. In this review, based on recent findings, we discuss the regulation and evolution of chlorophyll metabolism.
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Affiliation(s)
- Tatsuru Masuda
- Department of General Systems Studies, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Tokyo, 153-8902, Japan.
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Yamasato A, Tanaka R, Tanaka A. Loss of the N-terminal domain of chlorophyllide a oxygenase induces photodamage during greening of Arabidopsis seedlings. BMC PLANT BIOLOGY 2008; 8:64. [PMID: 18549471 PMCID: PMC2435540 DOI: 10.1186/1471-2229-8-64] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2007] [Accepted: 06/12/2008] [Indexed: 05/24/2023]
Abstract
BACKGROUND Chlorophyll b is a major photosynthetic pigment in green plants that is synthesized by chlorophyllide a oxygenase (CAO). The regulation of chlorophyll b biosynthesis is an important determinant for the antenna size of photosystems. Chlorophyll b synthesis is partly regulated on a transcriptional level by the expression of the CAO gene. In addition, the synthesis of chlorophyll b is strictly regulated on a protein level by the stability of the CAO enzyme. CAO consists of three domains, which are sequentially named from the N terminus as the A, B and C domains. The A domain of CAO participates in the regulation of the CAO protein stability. RESULTS In order to clarify the physiological function of the A domain, we constructed transgenic Arabidopsis (Arabidopsis thaliana) plants which either overexpressed the complete CAO or a truncated version of CAO lacking the A domain. The transgenic plants overexpressing the A-domain-deleted CAO accumulated an excess amount of chlorophyll b during greening. The transgenic plants which lacked the A domain either died or were obviously retarded when they were exposed to continuous light immediately after etiolation. In addition, the loss of the A domain in CAO impaired another step of chlorophyll biosynthesis, namely the conversion of divinyl-protochlorophyllide a to monovinyl protochlorophyllide a under dark conditions. CONCLUSION The A domain of CAO regulates the level of CAO, and thus prevents the excess accumulation of chlorophyll b. This function of the A domain is especially important during the greening stage of etiolated seedlings. At this stage, the plants are vulnerable to photodamages which could be caused by excessive chlorophyll b accumulation. In addition, de-regulation of the CAO level affects monovinyl-protochlorophyllide biosynthesis in darkness by unknown mechanisms. In conclusion, the A domain of CAO is essential in the control of chlorophyll biosynthesis and in the survival of seedlings during de-etiolation especially under strong illumination.
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Affiliation(s)
- Akihiro Yamasato
- Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan
- Division of Photobiology, National Institute for Basic Biology, Okazaki 444-8585, Japan
| | - Ryouichi Tanaka
- Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan
| | - Ayumi Tanaka
- Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan
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Masuda T. Recent overview of the Mg branch of the tetrapyrrole biosynthesis leading to chlorophylls. PHOTOSYNTHESIS RESEARCH 2008; 96:121-43. [PMID: 18273690 DOI: 10.1007/s11120-008-9291-4] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2007] [Accepted: 01/29/2008] [Indexed: 05/20/2023]
Abstract
In plants, chlorophylls (chlorophyll a and chlorophyll b) are the most abundant tetrapyrrole molecules and are essential for photosynthesis. The first committed step of chlorophyll biosynthesis is the insertion of Mg(2+) into protoporphyrin IX, and thus subsequent steps of the biosynthesis are called the Mg branch. As the Mg branch in higher plants is complex, it was not until the last decade--after many years of intensive research--that most of the genes encoding the enzymes for the pathway were identified. Biochemical and molecular genetic analyses have certainly modified the classic metabolic map of tetrapyrrole biosynthesis, and only recently have the molecular mechanisms of regulatory pathways governing chlorophyll metabolism been elucidated. As a result, novel functions of tetrapyrroles and biosynthetic enzymes have been proposed. In this review, I summarize the recent findings on enzymes involved in the Mg branch, mainly in higher plants.
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Affiliation(s)
- Tatsuru Masuda
- Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo 153-8902, Japan.
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Wu Z, Zhang X, He B, Diao L, Sheng S, Wang J, Guo X, Su N, Wang L, Jiang L, Wang C, Zhai H, Wan J. A chlorophyll-deficient rice mutant with impaired chlorophyllide esterification in chlorophyll biosynthesis. PLANT PHYSIOLOGY 2007; 145:29-40. [PMID: 17535821 PMCID: PMC1976586 DOI: 10.1104/pp.107.100321] [Citation(s) in RCA: 232] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Chlorophyll (Chl) synthase catalyzes esterification of chlorophyllide to complete the last step of Chl biosynthesis. Although the Chl synthases and the corresponding genes from various organisms have been well characterized, Chl synthase mutants have not yet been reported in higher plants. In this study, a rice (Oryza Sativa) Chl-deficient mutant, yellow-green leaf1 (ygl1), was isolated, which showed yellow-green leaves in young plants with decreased Chl synthesis, increased level of tetrapyrrole intermediates, and delayed chloroplast development. Genetic analysis demonstrated that the phenotype of ygl1 was caused by a recessive mutation in a nuclear gene. The ygl1 locus was mapped to chromosome 5 and isolated by map-based cloning. Sequence analysis revealed that it encodes the Chl synthase and its identity was verified by transgenic complementation. A missense mutation was found in a highly conserved residue of YGL1 in the ygl1 mutant, resulting in reduction of the enzymatic activity. YGL1 is constitutively expressed in all tissues, and its expression is not significantly affected in the ygl1 mutant. Interestingly, the mRNA expression of the cab1R gene encoding the Chl a/b-binding protein was severely suppressed in the ygl1 mutant. Moreover, the expression of some nuclear genes associated with Chl biosynthesis or chloroplast development was also affected in ygl1 seedlings. These results indicate that the expression of nuclear genes encoding various chloroplast proteins might be feedback regulated by the level of Chl or Chl precursors.
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Affiliation(s)
- Ziming Wu
- National Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, China
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Nakagawara E, Sakuraba Y, Yamasato A, Tanaka R, Tanaka A. Clp protease controls chlorophyll b synthesis by regulating the level of chlorophyllide a oxygenase. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2007; 49:800-9. [PMID: 17291312 DOI: 10.1111/j.1365-313x.2006.02996.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Chlorophyll b is one of the major light-harvesting pigments in green plants and it is essential for optimal light harvesting. Chlorophyll b is synthesized from chlorophyll a by chlorophyllide a oxygenase (CAO) which consists of A, B and C domains. Previously, we demonstrated that the C domain alone has a catalytic function, while the A and B domains control the level of CAO protein in response to chlorophyll b accumulation. We hypothesized that the accumulation of chlorophyll b triggers the proteolytic degradation of CAO. In this study, in order to gain further insight into this regulatory mechanism we screened for mutants that have defects in the control of CAO accumulation. Seeds from a transgenic line of Arabidopsis which overexpressed a CAO-GFP fusion were mutagenized and their progenies were screened by laser-scanning confocal microscopy for mutants showing an elevated level of GFP fluorescence. One particular mutant (dca1) exhibited stronger GFP fluorescence and accumulated a GFP-CAO fusion protein at a higher level. Concomitantly, the chlorophyll a to b ratio decreased in this mutant. The mutation in the dca1 mutant was mapped to the ClpC1 gene, thereby indicating that a chloroplast Clp protease is involved in regulating chlorophyll b biosynthesis through the destabilization of CAO protein in response to the accumulation of chlorophyll b.
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Affiliation(s)
- Eiki Nakagawara
- Institute of Low Temperature Science, Hokkaido University, N19 W8 Kita-ku, Sapporo, Japan
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Tanaka R, Tanaka A. Effects of chlorophyllide a oxygenase overexpression on light acclimation in Arabidopsis thaliana. PHOTOSYNTHESIS RESEARCH 2005; 85:327-40. [PMID: 16170635 DOI: 10.1007/s11120-005-6807-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2005] [Accepted: 04/28/2005] [Indexed: 05/04/2023]
Abstract
Land plants change the compositions of light-harvesting complexes (LHC) and chlorophyll (Chl) a/b ratios in response to the variable light environments which they encounter. In this study, we attempted to determine the mechanism which regulates Chl a/b ratios and whether the changes in Chl a/b ratios are essential in regulation of LHC accumulation during light acclimation. We hypothesized that changes in the mRNA levels for chlorophyll a oxygenase (CAO) involved in Chl b biosynthesis are an essential part of light response of Chl a/b ratios and LHC accumulation. We also examined the light-intensity dependent response of CAO-overexpression and wild-type Arabidopsis thaliana plants. When wild-type plants were acclimated from low-light (LL) to high-light (HL) conditions, CAO mRNA levels decreased and the Chl a/b ratio increased. In transgenic plants overexpressing CAO, the Chl a/b ratio remained low under HL conditions; thereby suggesting that changes in the CAO mRNA levels are necessary for those in Chl a/b ratios upon light acclimation. Under HL conditions, the accumulation of Lhcb1, Lhcb3 and Lhcb6 was enhanced in plants overexpressing CAO. On the contrary, in a CAO-deficient mutant, chlorina 1-1, theaccumulation of Lhcb1, Lhcb2, Lhcb3, Lhcb6 and Lhca4 was reduced. In comparison to wild-type, beta-carotene levels were reduced in CAO-overexpressing plants, while they were elevated in chlorina 1-1 mutants. These results imply that the transcriptional control of CAO is a part of the regulatory mechanism for the accumulation of a distinct set of LHC proteins upon light acclimation.
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Affiliation(s)
- Ryouichi Tanaka
- Institute of Low Temperature Science, CREST, Hokkaido University, Japan Science and Technology Corporation, N19 W8, 060-0819 Sapporo, Kita-ku, Japan.
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Kruk J. Occurrence of chlorophyll precursors in leaves of cabbage heads – the case of natural etiolation. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2005; 80:187-94. [PMID: 15936210 DOI: 10.1016/j.jphotobiol.2005.04.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2004] [Revised: 04/08/2005] [Accepted: 04/19/2005] [Indexed: 11/16/2022]
Abstract
In the interior of cabbage (Brassica oleracea) heads (kale, white cabbage, Brussels sprouts), natural leaf etiolation takes place due to a limited light access and chlorophyll biosynthesis is inhibited in a consequence. Instead, apart from carotenoids, whose biosynthesis is not light-dependent, chlorophyll precursors accumulate, mainly protochlorophyllide and to a smaller extent also chlorophyllides a and b. Protochlorophyllide was also detected in green, light-exposed leaves of heads of all the investigated cabbage varieties. Protochlorophyll was not found in the investigated leaves. The analysis of xanthophylls composition showed that the central leaves of kale and white cabbage heads contain relatively high amounts of trans-neoxanthin and lutein epoxide which are found only in trace amounts in green leaves. This is the first systematic study on natural occurrence of chlorophyll biosynthesis precursors in different cabbage varieties.
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Affiliation(s)
- Jerzy Kruk
- Department of Plant Physiology and Biochemistry, Faculty of Biotechnology, Jagiellonian University, ul. Gronostajowa 7, 30-387 Kraków, Poland.
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Pattanayak GK, Biswal AK, Reddy VS, Tripathy BC. Light-dependent regulation of chlorophyll b biosynthesis in chlorophyllide a oxygenase overexpressing tobacco plants. Biochem Biophys Res Commun 2005; 326:466-71. [PMID: 15582600 DOI: 10.1016/j.bbrc.2004.11.049] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2004] [Indexed: 11/17/2022]
Abstract
Chlorophyllide a oxygenase (CAO) that converts chlorophyllide a to chlorophyllide b was overexpressed in tobacco to increase chlorophyll (Chl) b biosynthesis and alter the Chl a/b ratio. Transgenic plants along with their wild-type cultivars were grown in low and high light intensities. In low light there was 20% increase in chlorophyll b contents in transgenic plants, which resulted in 16% reduction in the Chl a/b ratio. In high light, total Chl contents were 31% higher in transgenic plants than those of wild type. The increase in Chl a was 19% and that of Chl b was 72% leading to 31% decline of Chl a/b ratio. The increase in Chl b contents was accompanied by enhanced CAO expression that was highly pronounced in low light. As compared to low light, in high light Lhcb1 and Chl a/b transcripts abundance was significantly increased in transgenic plants suggesting a close relationship between Chl b synthesis and cab gene expression. However, there was a small increase in expression of LHCII proteins, which did not correspond to 72% increase in Chl b content in transgenic line, implying that LHCPII has the ability to bind more Chl b molecules.
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Affiliation(s)
- Gopal K Pattanayak
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 11067, India
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