301
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Gomez-Lobato ME, Civello PM, Martínez GA. Effects of ethylene, cytokinin and physical treatments on BoPaO gene expression of harvested broccoli. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2012; 92:151-8. [PMID: 21732385 DOI: 10.1002/jsfa.4555] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2011] [Revised: 04/19/2011] [Accepted: 06/09/2011] [Indexed: 05/09/2023]
Abstract
BACKGROUND Broccoli is a highly perishable vegetable that shows enhanced postharvest senescence and intense de-greening caused by chlorophyll degradation. One of the key steps of chlorophyll catabolism is the opening of chlorophyll tretrapyrrole catalysed by pheophorbide a oxygenase (PaO). In this study the expression of a gene encoding a putative PaO was characterised under several chemical and physical treatments. RESULTS A fragment of a gene encoding a PaO from broccoli (BoPaO) was cloned. The expression of BoPaO showed an important increment during postharvest senescence, in correlation with chlorophyll degradation. Furthermore, broccoli heads were treated with the hormones cytokinin and ethylene. Cytokinin delayed the increment in BoPaO expression, while ethylene accelerated the process. Also, several postharvest treatments were applied in order to evaluate their effect on BoPaO expression. Samples treated with modified atmosphere, hot air, UV-C or white light showed a delay in chlorophyll degradation and de-greening. In most cases the treatments also delayed the increment in BoPaO expression during senescence. CONCLUSION A close correlation between chlorophyll degradation and BoPaO expression was found during broccoli senescence. This relationship was corroborated in samples treated with different hormonal and physical applications.
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Affiliation(s)
- Maria Eugenia Gomez-Lobato
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús, UNSAM-CONICET, Camino Circunvalación Laguna Km 6, Chascomús (B7130IWA), Buenos Aires, Argentina
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302
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Sass L, Majer P, Hideg E. Leaf hue measurements: a high-throughput screening of chlorophyll content. Methods Mol Biol 2012; 918:61-9. [PMID: 22893286 DOI: 10.1007/978-1-61779-995-2_6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/16/2023]
Abstract
Computer analysis of digital photographic images provides fast, high-throughput screening of leaf pigmentation. Pixel-by-pixel conversion of red, green, blue (RGB) parameters to hue, saturation, value (HSV) showed that Hue values were proportional to total chlorophyll, offering an alternative to photometric analysis of leaf extracts. This is demonstrated using tobacco leaves with various chlorophyll contents due to senescence but shows the possibility of applications in studies of stress conditions accompanied by chlorophyll loss.
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Affiliation(s)
- László Sass
- Institute of Plant Physiology, Biological Research Centre, Szeged, Hungary
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303
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Comparative and Functional Genomics of Anoxygenic Green Bacteria from the Taxa Chlorobi, Chloroflexi, and Acidobacteria. FUNCTIONAL GENOMICS AND EVOLUTION OF PHOTOSYNTHETIC SYSTEMS 2012. [DOI: 10.1007/978-94-007-1533-2_3] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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304
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305
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Li H, Lin F, Wang G, Jing R, Zheng Q, Li B, Li Z. Quantitative trait loci mapping of dark-induced senescence in winter wheat (Triticum aestivum). JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2012; 54:33-44. [PMID: 22098940 DOI: 10.1111/j.1744-7909.2011.01088.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
In order to explore the genetics of dark-induced senescence in winter wheat (Triticum aestivum L.), a quantitative trait loci (QTL) analysis was carried out in a doubled haploid population developed from a cross between the varieties Hanxuan 10 (HX) and Lumai 14 (LM). The senescence parameters chlorophyll content (Chl a+b, Chl a, and Chl b), original fluorescence (Fo), maximum fluorescence level (Fm), maximum photochemical efficiency (Fv/Fm), and ratio of variable fluorescence to original fluorescence (Fv/Fo) were evaluated in the second leaf of whole three-leaf seedlings subjected to 7 d of darkness. A total of 43 QTLs were identified that were associated with dark-induced senescence using composite interval mapping. These QTLs were mapped to 20 loci distributed on 11 chromosomes: 1B, 1D, 2A, 2B, 3B, 3D, 5D, 6A, 6B, 7A, and 7B. The phenotypic variation explained by each QTL ranged from 7.5% to 19.4%. Eleven loci coincided with two or more of the analyzed parameters. In addition, 14 loci co-located or were linked with previously reported QTLs regulating flag leaf senescence, tolerance to high light stress, and grain protein content (Gpc), separately.
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Affiliation(s)
- Hongwei Li
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
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306
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Schulze K, López DA, Tillich UM, Frohme M. A simple viability analysis for unicellular cyanobacteria using a new autofluorescence assay, automated microscopy, and ImageJ. BMC Biotechnol 2011; 11:118. [PMID: 22129198 PMCID: PMC3247844 DOI: 10.1186/1472-6750-11-118] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Accepted: 11/30/2011] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Currently established methods to identify viable and non-viable cells of cyanobacteria are either time-consuming (eg. plating) or preparation-intensive (eg. fluorescent staining). In this paper we present a new and fast viability assay for unicellular cyanobacteria, which uses red chlorophyll fluorescence and an unspecific green autofluorescence for the differentiation of viable and non-viable cells without the need of sample preparation. RESULTS The viability assay for unicellular cyanobacteria using red and green autofluorescence was established and validated for the model organism Synechocystis sp. PCC 6803. Both autofluorescence signals could be observed simultaneously allowing a direct classification of viable and non-viable cells. The results were confirmed by plating/colony count, absorption spectra and chlorophyll measurements. The use of an automated fluorescence microscope and a novel ImageJ based image analysis plugin allow a semi-automated analysis. CONCLUSIONS The new method simplifies the process of viability analysis and allows a quick and accurate analysis. Furthermore results indicate that a combination of the new assay with absorption spectra or chlorophyll concentration measurements allows the estimation of the vitality of cells.
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Affiliation(s)
- Katja Schulze
- Molecular Biology and Functional Genomics, TH Wildau, Bahnhofstr. 1, 15745 Wildau, Germany
- Bioinformatics, University of Wuerzburg, Biocenter, Am Hubland, 97074 Wuerzburg, Germany
| | - Diana A López
- Molecular Biology and Functional Genomics, TH Wildau, Bahnhofstr. 1, 15745 Wildau, Germany
| | - Ulrich M Tillich
- Molecular Biology and Functional Genomics, TH Wildau, Bahnhofstr. 1, 15745 Wildau, Germany
| | - Marcus Frohme
- Molecular Biology and Functional Genomics, TH Wildau, Bahnhofstr. 1, 15745 Wildau, Germany
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307
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Zhang X, Zhang Z, Li J, Wu L, Guo J, Ouyang L, Xia Y, Huang X, Pang X. Correlation of leaf senescence and gene expression/activities of chlorophyll degradation enzymes in harvested Chinese flowering cabbage (Brassica rapa var. parachinensis). JOURNAL OF PLANT PHYSIOLOGY 2011; 168:2081-7. [PMID: 21820757 DOI: 10.1016/j.jplph.2011.06.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 06/23/2011] [Accepted: 06/24/2011] [Indexed: 05/20/2023]
Abstract
Chinese flowering cabbage is one of the main leafy vegetables produced in China. They have a rapid leaf yellowing due to chlorophyll degradation after harvest that limits their marketing. In the present study, leaf senescence of the cabbages was manipulated by ethylene and 6-benzyl aminopurine (6-BA) treatment to investigate the correlation of leaf senescence and chlorophyll degradation related to gene expression/activities in the darkness. The patterns of several senescence associated markers, including a typical marker, the expression of senescence-associated gene SAG(12), demonstrated that ethylene accelerated leaf senescence of the cabbages, while 6-BA retarded this progress. Similar to the trends of BrSAG(12) gene expression, strong activation in the expression of three chlorophyll degradation related genes, pheophytinase (BrPPH), pheophorbide a oxygenase (BrPAO) and red chlorophyll catabolite reductase (BrRCCR), was detected in ethylene treated and control leaves during the incubation, while no evident increase was recorded in 6-BA treated leaves. The overall dynamics of Mg-dechelatase activities in all treatments displayed increasing trends during the senescence process, and a delayed increase in the activities was observed for 6-BA treated leaves. However, chlorophyllase activity as well as the expression of BrChlase1 and BrChlase2 decreased with the incubation in all treatments. Taken together, the expression of BrPPH, BrPAO and BrRCCR, and the activity of Mg-dechelatase was closely associated with the chlorophyll degradation during the leaf senescence process in harvested Chinese flowering cabbages under dark conditions.
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Affiliation(s)
- Xuelian Zhang
- College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
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308
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Zhou C, Han L, Pislariu C, Nakashima J, Fu C, Jiang Q, Quan L, Blancaflor EB, Tang Y, Bouton JH, Udvardi M, Xia G, Wang ZY. From model to crop: functional analysis of a STAY-GREEN gene in the model legume Medicago truncatula and effective use of the gene for alfalfa improvement. PLANT PHYSIOLOGY 2011; 157:1483-96. [PMID: 21957014 PMCID: PMC3252161 DOI: 10.1104/pp.111.185140] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Accepted: 09/27/2011] [Indexed: 05/18/2023]
Abstract
Medicago truncatula has been developed into a model legume. Its close relative alfalfa (Medicago sativa) is the most widely grown forage legume crop in the United States. By screening a large population of M. truncatula mutants tagged with the transposable element of tobacco (Nicotiana tabacum) cell type1 (Tnt1), we identified a mutant line (NF2089) that maintained green leaves and showed green anthers, central carpels, mature pods, and seeds during senescence. Genetic and molecular analyses revealed that the mutation was caused by Tnt1 insertion in a STAY-GREEN (MtSGR) gene. Transcript profiling analysis of the mutant showed that loss of the MtSGR function affected the expression of a large number of genes involved in different biological processes. Further analyses revealed that SGR is implicated in nodule development and senescence. MtSGR expression was detected across all nodule developmental zones and was higher in the senescence zone. The number of young nodules on the mutant roots was higher than in the wild type. Expression levels of several nodule senescence markers were reduced in the sgr mutant. Based on the MtSGR sequence, an alfalfa SGR gene (MsSGR) was cloned, and transgenic alfalfa lines were produced by RNA interference. Silencing of MsSGR led to the production of stay-green transgenic alfalfa. This beneficial trait offers the opportunity to produce premium alfalfa hay with a more greenish appearance. In addition, most of the transgenic alfalfa lines retained more than 50% of chlorophylls during senescence and had increased crude protein content. This study illustrates the effective use of knowledge gained from a model system for the genetic improvement of an important commercial crop.
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309
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Saga Y, Miura R, Sadaoka K, Hirai Y. Kinetic Analysis of Demetalation of Synthetic Zinc Cyclic Tetrapyrroles Possessing an Acetyl Group at the 3-Position: Effects of Tetrapyrrole Structures and Peripheral Substitution. J Phys Chem B 2011; 115:11757-62. [DOI: 10.1021/jp206534x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yoshitaka Saga
- Department of Chemistry, Faculty of Science and Engineering, Kinki University, Higashi-Osaka, Osaka 577-8502, Japan
| | - Ryosuke Miura
- Department of Chemistry, Faculty of Science and Engineering, Kinki University, Higashi-Osaka, Osaka 577-8502, Japan
| | - Kana Sadaoka
- Department of Chemistry, Faculty of Science and Engineering, Kinki University, Higashi-Osaka, Osaka 577-8502, Japan
| | - Yuki Hirai
- Department of Chemistry, Faculty of Science and Engineering, Kinki University, Higashi-Osaka, Osaka 577-8502, Japan
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310
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Araújo WL, Tohge T, Ishizaki K, Leaver CJ, Fernie AR. Protein degradation - an alternative respiratory substrate for stressed plants. TRENDS IN PLANT SCIENCE 2011; 16:489-98. [PMID: 21684795 DOI: 10.1016/j.tplants.2011.05.008] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Revised: 05/11/2011] [Accepted: 05/17/2011] [Indexed: 05/18/2023]
Abstract
In cellular circumstances under which carbohydrates are scarce, plants can metabolize proteins and lipids as alternative respiratory substrates. Respiration of protein is less efficient than that of carbohydrate as assessed by the respiratory quotient; however, under certain adverse conditions, it represents an important alternative energy source for the cell. Significant effort has been invested in understanding the regulation of protein degradation in plants. This has included an investigation of how proteins are targeted to the proteosome, and the processes of senescence and autophagy. Here we review these events with particular reference to amino acid catabolism and its role in supporting the tricarboxylic acid cycle and direct electron supply to the ubiquinone pool of the mitochondrial electron transport chain in plants.
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Affiliation(s)
- Wagner L Araújo
- Max-Planck Institute for Molecular Plant Physiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
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311
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Meguro M, Ito H, Takabayashi A, Tanaka R, Tanaka A. Identification of the 7-hydroxymethyl chlorophyll a reductase of the chlorophyll cycle in Arabidopsis. THE PLANT CELL 2011; 23:3442-53. [PMID: 21934147 PMCID: PMC3203437 DOI: 10.1105/tpc.111.089714] [Citation(s) in RCA: 121] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 08/23/2011] [Accepted: 09/02/2011] [Indexed: 05/18/2023]
Abstract
The interconversion of chlorophyll a and chlorophyll b, referred to as the chlorophyll cycle, plays a crucial role in the processes of greening, acclimation to light intensity, and senescence. The chlorophyll cycle consists of three reactions: the conversions of chlorophyll a to chlorophyll b by chlorophyllide a oxygenase, chlorophyll b to 7-hydroxymethyl chlorophyll a by chlorophyll b reductase, and 7-hydroxymethyl chlorophyll a to chlorophyll a by 7-hydroxymethyl chlorophyll a reductase. We identified 7-hydroxymethyl chlorophyll a reductase, which is the last remaining unidentified enzyme of the chlorophyll cycle, from Arabidopsis thaliana by genetic and biochemical methods. Recombinant 7-hydroxymethyl chlorophyll a reductase converted 7-hydroxymethyl chlorophyll a to chlorophyll a using ferredoxin. Both sequence and biochemical analyses showed that 7-hydroxymethyl chlorophyll a reductase contains flavin adenine dinucleotide and an iron-sulfur center. In addition, a phylogenetic analysis elucidated the evolution of 7-hydroxymethyl chlorophyll a reductase from divinyl chlorophyllide vinyl reductase. A mutant lacking 7-hydroxymethyl chlorophyll a reductase was found to accumulate 7-hydroxymethyl chlorophyll a and pheophorbide a. Furthermore, this accumulation of pheophorbide a in the mutant was rescued by the inactivation of the chlorophyll b reductase gene. The downregulation of pheophorbide a oxygenase activity is discussed in relation to 7-hydroxymethyl chlorophyll a accumulation.
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Affiliation(s)
| | - Hisashi Ito
- Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan
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312
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Parlitz S, Kunze R, Mueller-Roeber B, Balazadeh S. Regulation of photosynthesis and transcription factor expression by leaf shading and re-illumination in Arabidopsis thaliana leaves. JOURNAL OF PLANT PHYSIOLOGY 2011; 168:1311-9. [PMID: 21377757 DOI: 10.1016/j.jplph.2011.02.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 01/29/2011] [Accepted: 02/01/2011] [Indexed: 05/05/2023]
Abstract
Leaf senescence of annual plants is a genetically programmed developmental phase. The onset of leaf senescence is however not exclusively determined by tissue age but is modulated by various environmental factors. Shading of individual attached leaves evokes dark-induced senescence. The initiation and progression of dark-induced senescence depend on the plant and the age of the affected leaf, however. In several plant species dark-induced senescence is fully reversible upon re-illumination and the leaves can regreen, but the regreening ability depends on the duration of dark incubation. We studied the ability of Arabidopsis thaliana leaves to regreen after dark-incubation with the aim to identify transcription factors (TFs) that are involved in the regulation of early dark-induced senescence and regreening. Two days shading of individual attached leaves triggers the transition into a pre-senescence state from which the leaves can largely recover. Longer periods of darkness result in irreversible senescence. Large scale qRT-PCR analysis of 1872 TF genes revealed that 649 of them are regulated in leaves during normal development, upon shading or re-illumination. Leaf shading triggered upregulation of 150 TF genes, some of which are involved in controlling senescence. Of those, 39 TF genes were upregulated after two days in the dark and regained pre-shading expression level after two days of re-illumination. Furthermore, a larger number of 422 TF genes were down regulated upon shading. In TF gene clusters with different expression patterns certain TF families are over-represented.
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Affiliation(s)
- Steffi Parlitz
- Free University of Berlin, Institute for Biology/Applied Genetics, Albrecht-Thaer-Weg 6, Berlin, Germany
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313
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Tanaka R, Kobayashi K, Masuda T. Tetrapyrrole Metabolism in Arabidopsis thaliana. THE ARABIDOPSIS BOOK 2011; 9:e0145. [PMID: 22303270 PMCID: PMC3268503 DOI: 10.1199/tab.0145] [Citation(s) in RCA: 152] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Higher plants produce four classes of tetrapyrroles, namely, chlorophyll (Chl), heme, siroheme, and phytochromobilin. In plants, tetrapyrroles play essential roles in a wide range of biological activities including photosynthesis, respiration and the assimilation of nitrogen/sulfur. All four classes of tetrapyrroles are derived from a common biosynthetic pathway that resides in the plastid. In this article, we present an overview of tetrapyrrole metabolism in Arabidopsis and other higher plants, and we describe all identified enzymatic steps involved in this metabolism. We also summarize recent findings on Chl biosynthesis and Chl breakdown. Recent advances in this field, in particular those on the genetic and biochemical analyses of novel enzymes, prompted us to redraw the tetrapyrrole metabolic pathways. In addition, we also summarize our current understanding on the regulatory mechanisms governing tetrapyrrole metabolism. The interactions of tetrapyrrole biosynthesis and other cellular processes including the plastid-to-nucleus signal transduction are discussed.
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Affiliation(s)
- Ryouichi Tanaka
- Institute of Low Temperature Science, Hokkaido University, Sapporo, Japan
| | | | - Tatsuru Masuda
- Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
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314
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Almeida J, Quadrana L, Asís R, Setta N, de Godoy F, Bermúdez L, Otaiza SN, Corrêa da Silva JV, Fernie AR, Carrari F, Rossi M. Genetic dissection of vitamin E biosynthesis in tomato. JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:3781-98. [PMID: 21527625 PMCID: PMC3134339 DOI: 10.1093/jxb/err055] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Revised: 02/07/2011] [Accepted: 02/08/2011] [Indexed: 05/20/2023]
Abstract
Vegetables are critical for human health as they are a source of multiple vitamins including vitamin E (VTE). In plants, the synthesis of VTE compounds, tocopherol and tocotrienol, derives from precursors of the shikimate and methylerythritol phosphate pathways. Quantitative trait loci (QTL) for α-tocopherol content in ripe fruit have previously been determined in an Solanum pennellii tomato introgression line population. In this work, variations of tocopherol isoforms (α, β, γ, and δ) in ripe fruits of these lines were studied. In parallel all tomato genes structurally associated with VTE biosynthesis were identified and mapped. Previously identified VTE QTL on chromosomes 6 and 9 were confirmed whilst novel ones were identified on chromosomes 7 and 8. Integrated analysis at the metabolic, genetic and genomic levels allowed us to propose 16 candidate loci putatively affecting tocopherol content in tomato. A comparative analysis revealed polymorphisms at nucleotide and amino acid levels between Solanum lycopersicum and S. pennellii candidate alleles. Moreover, evolutionary analyses showed the presence of codons evolving under both neutral and positive selection, which may explain the phenotypic differences between species. These data represent an important step in understanding the genetic determinants of VTE natural variation in tomato fruit and as such in the ability to improve the content of this important nutriceutical.
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Affiliation(s)
- Juliana Almeida
- Departamento de Botânica-IB-USP, 277, 05508-900, São Paulo, SP, Brazil
| | - Leandro Quadrana
- Instituto de Biotecnología, Instituto Nacional de Tecnología Agropecuaría (IB-INTA), and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), PO Box 25, B1712WAA Castelar, Argentina (partner group of the Max Planck Institute for Molecular Plant Physiology, Potsdam-Golm, Germany)
| | - Ramón Asís
- CIBICI, Facultad de Ciencias Químicas Universidad Nacional de Córdoba, CC 5000, Córdoba, Argentina
| | - Nathalia Setta
- Departamento de Botânica-IB-USP, 277, 05508-900, São Paulo, SP, Brazil
| | - Fabiana de Godoy
- Departamento de Botânica-IB-USP, 277, 05508-900, São Paulo, SP, Brazil
| | - Luisa Bermúdez
- Departamento de Botânica-IB-USP, 277, 05508-900, São Paulo, SP, Brazil
| | - Santiago N. Otaiza
- CIBICI, Facultad de Ciencias Químicas Universidad Nacional de Córdoba, CC 5000, Córdoba, Argentina
| | | | - Alisdair R. Fernie
- Max Planck Institute for Molecular Plant Physiology, Wissenschaftspark Golm, Am Mühlenberg 1, Potsdam-Golm, D-14476, Germany
| | - Fernando Carrari
- Instituto de Biotecnología, Instituto Nacional de Tecnología Agropecuaría (IB-INTA), and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), PO Box 25, B1712WAA Castelar, Argentina (partner group of the Max Planck Institute for Molecular Plant Physiology, Potsdam-Golm, Germany)
| | - Magdalena Rossi
- Departamento de Botânica-IB-USP, 277, 05508-900, São Paulo, SP, Brazil
- To whom correspondence should be addressed. E-mail: ; E-mail:
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315
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Wei Q, Guo Y, Kuai B. Isolation and characterization of a chlorophyll degradation regulatory gene from tall fescue. PLANT CELL REPORTS 2011; 30:1201-7. [PMID: 21327390 DOI: 10.1007/s00299-011-1028-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Revised: 01/18/2011] [Accepted: 01/26/2011] [Indexed: 05/15/2023]
Abstract
The non-yellowing gene (NYE1), initially identified from Arabidopsis, is a key regulatory gene responsible for chlorophyll degradation during senescence. Here, FaNYE1, an orthologue of AtNYE1, was further identified from a major type of cool-season turf grass, tall fescue (Festuca arundinacea Schreb.), by RACE-PCR. It consists of 1,441 bp, with an open reading frame of 834 bp, encoding a predicted polypeptide of 278 amino acids. Sequence similarity as well as exon and intron characteristics clearly suggested that FaNYE1 encoded an AtNYE1-like chloroplast protein. FaNYE1 could be strongly induced by dark treatment and natural senescence. FaNYE1, driven by a 1.5 kb upstream fragment of AtNYE1, could rescue the stay-green phenotype of nye1-1. Constitutive overexpression of FaNYE1 in Arabidopsis resulted in the whole spectrum of leaf yellowing phenotypes, the severity of which correlates with its transcript level. These results collectively indicate that FaNYE1 might play an important regulatory role in chlorophyll degradation during senescence in tall fescue, and therefore is a valuable gene for improving the green period or lawn color of turf grasses by genetic engineering.
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Affiliation(s)
- Qiang Wei
- State Key Laboratory of Genetic Engineering and Institute of Plant Biology, School of Life Sciences, Fudan University, 220 Handan Road, Shanghai, China
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316
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Yandeau-Nelson MD, Laurens L, Shi Z, Xia H, Smith AM, Guiltinan MJ. Starch-branching enzyme IIa is required for proper diurnal cycling of starch in leaves of maize. PLANT PHYSIOLOGY 2011; 156:479-90. [PMID: 21508184 PMCID: PMC3177252 DOI: 10.1104/pp.111.174094] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Accepted: 04/13/2011] [Indexed: 05/23/2023]
Abstract
Starch-branching enzyme (SBE), a glucosyl transferase, is required for the highly regular pattern of α-1,6 bonds in the amylopectin component of starch. In the absence of SBEIIa, as shown previously in the sbe2a mutant of maize (Zea mays), leaf starch has drastically reduced branching and the leaves exhibit a severe senescence-like phenotype. Detailed characterization of the maize sbe2a mutant revealed that SBEIIa is the primary active branching enzyme in the leaf and that in its absence plant growth is affected. Both seedling and mature sbe2a mutant leaves do not properly degrade starch during the night, resulting in hyperaccumulation. In mature sbe2a leaves, starch hyperaccumulation is greatest in visibly senescing regions but also observed in green tissue and is correlated to a drastic reduction in photosynthesis within the leaf. Starch granules from sbe2a leaves observed via scanning electron microscopy and transmission electron microscopy analyses are larger, irregular, and amorphous as compared with the highly regular, discoid starch granules observed in wild-type leaves. This appears to trigger premature senescence, as shown by an increased expression of genes encoding proteins known to be involved in senescence and programmed cell death processes. Together, these results indicate that SBEIIa is required for the proper diurnal cycling of transitory starch within the leaf and suggest that SBEIIa is necessary in producing an amylopectin structure amenable to degradation by starch metabolism enzymes.
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Affiliation(s)
| | | | | | | | | | - Mark J. Guiltinan
- Department of Horticulture (M.D.Y.-N., Z.S., M.J.G.) and Department of Food Science (H.X.), Pennsylvania State University, University Park, Pennsylvania 16802; John Innes Centre, Norwich NR4 7UH, United Kingdom (L.L., A.M.S.)
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317
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Büchert AM, Civello PM, Martínez GA. Chlorophyllase versus pheophytinase as candidates for chlorophyll dephytilation during senescence of broccoli. JOURNAL OF PLANT PHYSIOLOGY 2011; 168:337-43. [PMID: 20727617 DOI: 10.1016/j.jplph.2010.07.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Revised: 07/24/2010] [Accepted: 07/24/2010] [Indexed: 05/24/2023]
Abstract
Degradation of chlorophylls during senescence is a highly regulated process which requires the concerted action of several enzymes. Traditionally, it has been stated that the dismantling process of the chlorophyll molecule begins with a dephytilation step, followed by Mg(2+) removal and other breakdown reactions. Recently, new evidence suggests the possibility of a rearrangement in the first two steps of this process, occurring Mg(2+) removal prior to the loss of the phytol side chain. With the purpose of approximating to the real sequential order of these reactions and to assess if dephytilation occurs on intact (catalyzed by chlorophyllase) or Mg-free (catalyzed by pheophytinase) chlorophyll, expression of both genes was analyzed in broccoli tissue during senescence. Samples of broccoli florets treated with plant hormones, such as cytokinin and ethylene were utilized, as to assess the effect of such compounds on the expression of these genes. Results showed that chlorophyllase expression did not correlate to typical expression patterns for genes related to senescence, since a decrease in expression during senescence was found for one of the two chlorophyllase genes analyzed, and the hormonal-treatment effects on gene expression did not match those observed on chlorophyll content for both chlorophyllase genes. Pheophytinase expression patterns, on the other hand, displayed an increase in the first 3 days of induced senescence, followed by lower expression values towards the end of the experiment. Samples subjected to postharvest treatments mostly showed an inhibition of pheophytinase expression, especially in samples in which degradation of chlorophylls had been delayed. These results suggest that pheophytinase expression correlates to the visual manifestation of postharvest treatments, supporting the possibility that this enzyme is responsible for the dephytilation step in chlorophyll breakdown.
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Affiliation(s)
- Agustin M Büchert
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús (IIB-INTECH) UNSAM-CONICET, Camino Circunvalación Laguna Km 6, Chascomús, Buenos Aires, Argentina
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318
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Hirai Y, Sasaki SI, Tamiaki H, Kashimura S, Saga Y. Substitution Effects in the A- and B-Rings of the Chlorin Macrocycle on Demetalation Properties of Zinc Chlorophyll Derivatives. J Phys Chem B 2011; 115:3240-4. [DOI: 10.1021/jp1117486] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yuki Hirai
- Department of Chemistry, Faculty of Science and Engineering, Kinki University, Higashi-Osaka, Osaka 577-8502, Japan
| | - Shin-ichi Sasaki
- Department of Bioscience and Biotechnology, Faculty of Science and Engineering, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
- Nagahama Institute of Bio-Science and Technology, Nagahama, Shiga 526-0829, Japan
| | - Hitoshi Tamiaki
- Department of Bioscience and Biotechnology, Faculty of Science and Engineering, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Shigenori Kashimura
- Department of Chemistry, Faculty of Science and Engineering, Kinki University, Higashi-Osaka, Osaka 577-8502, Japan
| | - Yoshitaka Saga
- Department of Chemistry, Faculty of Science and Engineering, Kinki University, Higashi-Osaka, Osaka 577-8502, Japan
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319
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Ulrich M, Moser S, Müller T, Kräutler B. How the colourless 'nonfluorescent' chlorophyll catabolites rust. Chemistry 2011; 17:2330-4. [PMID: 21308817 PMCID: PMC3072522 DOI: 10.1002/chem.201003313] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Indexed: 12/01/2022]
Affiliation(s)
- Markus Ulrich
- Institute of Organic Chemistry and Centre of Molecular Biosciences, University of Innsbruck, Innrain 52a, 6020 Innsbruck, Austria
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320
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Bhuyan J, Sarkar S. Oxidative degradation of zinc porphyrin in comparison with its iron analogue. Chemistry 2011; 16:10649-52. [PMID: 20687149 DOI: 10.1002/chem.201001073] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Jagannath Bhuyan
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, U.P., India
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321
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Hirai Y, Kashimura S, Saga Y. Demetalation Kinetics of Chlorophyll Derivatives Possessing Different Substituents at the 7-Position Under Acidic Conditions. Photochem Photobiol 2011; 87:302-7. [DOI: 10.1111/j.1751-1097.2010.00874.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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322
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Niu J, Zhang W, Feng Z, Wang X, Tian Y. Impact of elevated O3 on visible foliar symptom, growth and biomass of Cinnamomum camphora seedlings under different nitrogen loads. ACTA ACUST UNITED AC 2011; 13:2873-9. [DOI: 10.1039/c1em10305a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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323
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Pheophorbide a: A photosensitizer with immunostimulating activities on mouse macrophage RAW 264.7 cells in the absence of irradiation. Cell Immunol 2011; 269:60-7. [DOI: 10.1016/j.cellimm.2011.02.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Revised: 12/30/2010] [Accepted: 02/16/2011] [Indexed: 01/24/2023]
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324
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Hörtensteiner S, Kräutler B. Chlorophyll breakdown in higher plants. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1807:977-88. [PMID: 21167811 DOI: 10.1016/j.bbabio.2010.12.007] [Citation(s) in RCA: 372] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Revised: 12/07/2010] [Accepted: 12/08/2010] [Indexed: 01/05/2023]
Abstract
Chlorophyll breakdown is an important catabolic process of leaf senescence and fruit ripening. Structure elucidation of colorless linear tetrapyrroles as (final) breakdown products of chlorophyll was crucial for the recent delineation of a chlorophyll breakdown pathway which is highly conserved in land plants. Pheophorbide a oxygenase is the key enzyme responsible for opening of the chlorin macrocycle of pheophorbide a characteristic to all further breakdown products. Degradation of chlorophyll was rationalized by the need of a senescing cell to detoxify the potentially phototoxic pigment, yet recent investigations in leaves and fruits indicate that chlorophyll catabolites could have physiological roles. This review updates structural information of chlorophyll catabolites and the biochemical reactions involved in their formation, and discusses the significance of chlorophyll breakdown. This article is part of a Special Issue entitled: Regulation of Electron Transport in Chloroplasts.
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Affiliation(s)
- Stefan Hörtensteiner
- Institute of Plant Biology, University of Zurich, Zollikerstrasse 107, CH-8008 Zurich, Switzerland.
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325
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Banala S, Moser S, Müller T, Kreutz C, Holzinger A, Lütz C, Kräutler B. Hypermodified fluorescent chlorophyll catabolites: source of blue luminescence in senescent leaves. Angew Chem Int Ed Engl 2010; 49:5174-7. [PMID: 20533476 DOI: 10.1002/anie.201000294] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Srinivas Banala
- Institute of Organic Chemistry and Centre of Molecular Biosciences, University of Innsbruck, 6020 Innsbruck, Austria
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326
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Mur LAJ, Aubry S, Mondhe M, Kingston-Smith A, Gallagher J, Timms-Taravella E, James C, Papp I, Hörtensteiner S, Thomas H, Ougham H. Accumulation of chlorophyll catabolites photosensitizes the hypersensitive response elicited by Pseudomonas syringae in Arabidopsis. THE NEW PHYTOLOGIST 2010; 188:161-74. [PMID: 20704660 DOI: 10.1111/j.1469-8137.2010.03377.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
• The staygreen (SGR) gene encodes a chloroplast-targeted protein which promotes chlorophyll degradation via disruption of light-harvesting complexes (LHCs). • Over-expression of SGR in Arabidopsis (SGR-OX) in a Columbia-0 (Col-0) background caused spontaneous necrotic flecking. To relate this to the hypersensitive response (HR), Col-0, SGR-OX and RNAi SGR (SGRi) lines were challenged with Pseudomonas syringae pv tomato (Pst) encoding the avirulence gene avrRpm1. Increased and decreased SGR expression, respectively, accelerated and suppressed the kinetics of HR-cell death. In Col-0, SGR transcript increased at 6 h after inoculation (hai) when tissue electrolyte leakage indicated the initiation of cell death. • Excitation of the chlorophyll catabolite pheophorbide (Pheide) leads to the formation of toxic singlet oxygen ((1)O(2)). Pheide was first detected at 6 hai with Pst avrRpm1 and was linked to (1)O(2) generation and correlated with reduced Pheide a oxygenase (PaO) protein concentrations. The maximum quantum efficiency of photosystem II (F(v)/F(m)), quantum yield of electron transfer at photosystem II (φPSII), and photochemical quenching (qP) decreased at 6 hai in Col-0 but not in SGRi. Disruption of photosynthetic electron flow will cause light-dependent H(2)O(2) generation at 6 hai. • We conclude that disruption of LHCs, possibly influenced by SGR, and absence of PaO produce phototoxic chlorophyll catabolites and oxidative stress leading to the HR.
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Affiliation(s)
- Luis A J Mur
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Ceredigion SY23 3DA, UK.
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327
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Crystal Structures of the Substrate-Bound Forms of Red Chlorophyll Catabolite Reductase: Implications for Site-Specific and Stereospecific Reaction. J Mol Biol 2010; 402:879-91. [DOI: 10.1016/j.jmb.2010.08.021] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2010] [Revised: 08/07/2010] [Accepted: 08/11/2010] [Indexed: 01/05/2023]
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328
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Lee GC, Chepyshko H, Chen HH, Chu CC, Chou YF, Akoh CC, Shaw JF. Genes and biochemical characterization of three novel chlorophyllase isozymes from Brassica oleracea. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:8651-8657. [PMID: 20681655 DOI: 10.1021/jf1016384] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Three full length cDNAs (BoCLH1, 1140 bp; BoCLH2, 1104 bp; BoCLH3, 884 bp) encoding putative chlorophyllases were cloned from the cDNA pools of broccoli (Brassica oleracea) florets and characterized. The amino acid sequence analysis indicated that these three BoCLHs contained a highly conserved lipase motif (GXSXG). However, only BoCLH3 lacked the His residue which is the component of the catalytic triad (Ser-His-Asp). N-terminal sequences of BoCLH1 and BoCLH2 were predicted to have typical signal sequences for the chloroplast, whereas the plasma membrane-targeting sequence was identified in BoCLH3. The predicted molecular masses of BoCLH1, 2, and 3 were 34.7, 35.3, and 23.5 kDa, respectively. The recombinant BoCLHs were successfully expressed in Escherichia coli for the biochemical characterization. The recombinant BoCLH3 showed very low chlorophyllase activity possibly due to its incomplete catalytic triad. BoCLH1 and BoCLH2 showed significant differences in biochemical properties such as pH stability and temperature optimum. Kinetic analysis revealed that BoCLH1 preferably hydrolyzed Mg-free chlorophyll, while BoCLH2 hydrolyzed both chlorophyll and Mg-free chlorophyll at a similar level. Different characteristics between BoCLH1 and BoCLH2 implied that they may have different physiological functions in broccoli. The catalytic triad of recombinant BoCLH2 was identified as Ser141, His247, and Asp170 by site-directed mutagenesis. It suggested that the three broccoli chlorophyllase isozymes were serine hydrolases.
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Affiliation(s)
- Guan-Chiun Lee
- Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
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329
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Saga Y, Hojo S, Hirai Y. Comparison of demetalation properties between zinc chlorin and zinc porphyrin derivatives: Effect of macrocyclic structures. Bioorg Med Chem 2010; 18:5697-700. [DOI: 10.1016/j.bmc.2010.06.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Revised: 06/04/2010] [Accepted: 06/05/2010] [Indexed: 11/28/2022]
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330
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Banala S, Moser S, Müller T, Kreutz C, Holzinger A, Lütz C, Kräutler B. Hypermodifizierte fluoreszierende Chlorophyllkataboliten als Quelle blauer Lumineszenz in seneszenten Blättern. Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.201000294] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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331
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Moyano MJ, Heredia FJ, Meléndez-Martínez AJ. The Color of Olive Oils: The Pigments and Their Likely Health Benefits and Visual and Instrumental Methods of Analysis. Compr Rev Food Sci Food Saf 2010; 9:278-291. [DOI: 10.1111/j.1541-4337.2010.00109.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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332
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Araújo WL, Ishizaki K, Nunes-Nesi A, Larson TR, Tohge T, Krahnert I, Witt S, Obata T, Schauer N, Graham IA, Leaver CJ, Fernie AR. Identification of the 2-hydroxyglutarate and isovaleryl-CoA dehydrogenases as alternative electron donors linking lysine catabolism to the electron transport chain of Arabidopsis mitochondria. THE PLANT CELL 2010; 22:1549-63. [PMID: 20501910 PMCID: PMC2899879 DOI: 10.1105/tpc.110.075630] [Citation(s) in RCA: 240] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Revised: 05/05/2010] [Accepted: 05/10/2010] [Indexed: 05/17/2023]
Abstract
The process of dark-induced senescence in plants is relatively poorly understood, but a functional electron-transfer flavoprotein/electron-transfer flavoprotein:ubiquinone oxidoreductase (ETF/ETFQO) complex, which supports respiration during carbon starvation, has recently been identified. Here, we studied the responses of Arabidopsis thaliana mutants deficient in the expression of isovaleryl-CoA dehydrogenase and 2-hydroxyglutarate dehydrogenase to extended darkness and other environmental stresses. Evaluations of the mutant phenotypes following carbon starvation induced by extended darkness identify similarities to those exhibited by mutants of the ETF/ETFQO complex. Metabolic profiling and isotope tracer experimentation revealed that isovaleryl-CoA dehydrogenase is involved in degradation of the branched-chain amino acids, phytol, and Lys, while 2-hydroxyglutarate dehydrogenase is involved exclusively in Lys degradation. These results suggest that isovaleryl-CoA dehydrogenase is the more critical for alternative respiration and that a series of enzymes, including 2-hydroxyglutarate dehydrogenase, plays a role in Lys degradation. Both physiological and metabolic phenotypes of the isovaleryl-CoA dehydrogenase and 2-hydroxyglutarate dehydrogenase mutants were not as severe as those observed for mutants of the ETF/ETFQO complex, indicating some functional redundancy of the enzymes within the process. Our results aid in the elucidation of the pathway of plant Lys catabolism and demonstrate that both isovaleryl-CoA dehydrogenase and 2-hydroxyglutarate dehydrogenase act as electron donors to the ubiquinol pool via an ETF/ETFQO-mediated route.
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Affiliation(s)
- Wagner L. Araújo
- Max Planck Institut für Molekulare Pflanzenphysiologie, 14476 Golm, Germany
| | | | - Adriano Nunes-Nesi
- Max Planck Institut für Molekulare Pflanzenphysiologie, 14476 Golm, Germany
| | - Tony R. Larson
- Department of Biology, Centre for Novel Agricultural Products, University of York, Heslington, York YO10 5YW, United Kingdom
| | - Takayuki Tohge
- Max Planck Institut für Molekulare Pflanzenphysiologie, 14476 Golm, Germany
| | - Ina Krahnert
- Max Planck Institut für Molekulare Pflanzenphysiologie, 14476 Golm, Germany
| | - Sandra Witt
- Max Planck Institut für Molekulare Pflanzenphysiologie, 14476 Golm, Germany
| | - Toshihiro Obata
- Max Planck Institut für Molekulare Pflanzenphysiologie, 14476 Golm, Germany
| | - Nicolas Schauer
- Max Planck Institut für Molekulare Pflanzenphysiologie, 14476 Golm, Germany
| | - Ian A. Graham
- Department of Biology, Centre for Novel Agricultural Products, University of York, Heslington, York YO10 5YW, United Kingdom
| | | | - Alisdair R. Fernie
- Max Planck Institut für Molekulare Pflanzenphysiologie, 14476 Golm, Germany
- Address correspondence to
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333
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Hynninen PH, Kaartinen V, Kolehmainen E. Horseradish peroxidase-catalyzed oxidation of chlorophyll a with hydrogen peroxide. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:531-42. [DOI: 10.1016/j.bbabio.2010.01.017] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2009] [Revised: 01/11/2010] [Accepted: 01/15/2010] [Indexed: 11/16/2022]
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334
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Ren G, Zhou Q, Wu S, Zhang Y, Zhang L, Huang J, Sun Z, Kuai B. Reverse genetic identification of CRN1 and its distinctive role in chlorophyll degradation in Arabidopsis. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2010; 52:496-504. [PMID: 20537045 DOI: 10.1111/j.1744-7909.2010.00945.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Recent identification of NYE1/SGR1 brought up a new era for the exploration of the regulatory mechanism of Chlorophyll (Chl) degradation. Cluster analysis of senescence associated genes with putative chloroplast targeting sequences revealed several genes sharing a similar expression pattern with NYE1. Further characterization of available T-DNA insertion lines led to the discovery of a novel stay-green gene CRN1 (Co-regulated with NYE1). Chl breakdown was significantly restrained in crn1-1 under diversified senescence scenarios, which is comparable with that in acd1-20, but much more severe than that in nye1-1. Notably, various Chl binding proteins, especially trimeric LHCP II, were markedly retained in crn1-1 four days after dark-treatment, possibly due to a lesion in disassociation of protein-pigment complex. Nevertheless, the photochemical efficiency of PSII in crn1-1 declined, even more rapidly, two days after dark-treatment, compared to those in Col-0 and nye1-1. Our results suggest that CRN1 plays a crucial role in Chl degradation, and that loss of its function produces various side-effects, including those on the breakdown of Ch-protein complex and the maintenance of the residual photosynthetic capability during leaf senescence.
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Affiliation(s)
- Guodong Ren
- State Key Laboratory of Genetic Engineering, Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai 200433, China
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335
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JIANG SK, ZHANG XJ, XU ZJ, CHEN WF. Comparison between QTLs for Chlorophyll Content and Genes Control-ling Chlorophyll Biosynthesis and Degradation in Japonica Rice ( Oryza sativa L.). ZUOWU XUEBAO 2010. [DOI: 10.3724/sp.j.1006.2010.00376] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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336
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Mohapatra PK, Patro L, Raval MK, Ramaswamy NK, Biswal UC, Biswal B. Senescence-induced loss in photosynthesis enhances cell wall beta-glucosidase activity. PHYSIOLOGIA PLANTARUM 2010; 138:346-55. [PMID: 20028477 DOI: 10.1111/j.1399-3054.2009.01327.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
A link between senescence-induced decline in photosynthesis and activity of beta-glucosidase is examined in the leaves of Arabidopsis. The enzyme is purified and characterized. The molecular weight of the enzyme is 58 kDa. It shows maximum activity at pH 5.5 and at temperature of 50 degrees C. Photosynthetic measurements and activity of the enzyme are conducted at different developmental stages including senescence of leaves. Senescence causes a significant loss in total chlorophyll, stomatal conductance, rate of evaporation and in the ability of the leaves for carbon dioxide fixation. The process also brings about a decline in oxygen evolution, quantum yield of photosystem II (PS II) and quantum efficiency of PS II photochemistry of thylakoid membrane. The loss in photosynthesis is accompanied by a significant increase in the activity of the cell wall-bound beta-glucosidase that breaks down polysaccharides to soluble sugars. The loss in photosynthesis as a signal for the enhancement in the activity of the enzyme is confirmed from the observation that incubation of excised mature leaves in continuous dark or in light with a photosynthesis inhibitor 3-(3,4-dichlorophenyl)-1, 1-dimethylurea (DCMU) that leads to sugar starvation enhances the activity of the enzyme. The work suggests that in the background of photosynthetic decline, the polysaccharides bound to cell wall that remains intact even during late phase of senescence may be the last target of senescing leaves for a possible source of sugar for remobilization and completion of the energy-dependent senescence program.
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Affiliation(s)
- Pranab Kishor Mohapatra
- Laboratory of Biochemistry and Biophysics, School of Life Sciences, Sambalpur University, Jyoti Vihar 768019, Orissa, India
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337
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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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338
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Nagao R, Tomo T, Noguchi E, Nakajima S, Suzuki T, Okumura A, Kashino Y, Mimuro M, Ikeuchi M, Enami I. Purification and characterization of a stable oxygen-evolving Photosystem II complex from a marine centric diatom, Chaetoceros gracilis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:160-6. [DOI: 10.1016/j.bbabio.2009.09.008] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2009] [Revised: 09/12/2009] [Accepted: 09/16/2009] [Indexed: 11/28/2022]
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339
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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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340
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Drought response in the spikes of barley: gene expression in the lemma, palea, awn, and seed. Funct Integr Genomics 2009; 10:191-205. [DOI: 10.1007/s10142-009-0149-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2009] [Revised: 10/01/2009] [Accepted: 10/21/2009] [Indexed: 10/20/2022]
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341
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Stettler M, Eicke S, Mettler T, Messerli G, Hörtensteiner S, Zeeman SC. Blocking the metabolism of starch breakdown products in Arabidopsis leaves triggers chloroplast degradation. MOLECULAR PLANT 2009; 2:1233-46. [PMID: 19946617 PMCID: PMC2782796 DOI: 10.1093/mp/ssp093] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2009] [Accepted: 09/29/2009] [Indexed: 05/18/2023]
Abstract
In most plants, a large fraction of photo-assimilated carbon is stored in the chloroplasts during the day as starch and remobilized during the subsequent night to support metabolism. Mutations blocking either starch synthesis or starch breakdown in Arabidopsis thaliana reduce plant growth. Maltose is the major product of starch breakdown exported from the chloroplast at night. The maltose excess 1 mutant (mex1), which lacks the chloroplast envelope maltose transporter, accumulates high levels of maltose and starch in chloroplasts and develops a distinctive but previously unexplained chlorotic phenotype as leaves mature. The introduction of additional mutations that prevent starch synthesis, or that block maltose production from starch, also prevent chlorosis of mex1. In contrast, introduction of mutations in disproportionating enzyme (DPE1) results in the accumulation of maltotriose in addition to maltose, and greatly increases chlorosis. These data suggest a link between maltose accumulation and chloroplast homeostasis. Microscopic analyses show that the mesophyll cells in chlorotic mex1 leaves have fewer than half the number of chloroplasts than wild-type cells. Transmission electron microscopy reveals autophagy-like chloroplast degradation in both mex1 and the dpe1/mex1 double mutant. Microarray analyses reveal substantial reprogramming of metabolic and cellular processes, suggesting that organellar protein turnover is increased in mex1, though leaf senescence and senescence-related chlorophyll catabolism are not induced. We propose that the accumulation of maltose and malto-oligosaccharides causes chloroplast dysfunction, which may by signaled via a form of retrograde signaling and trigger chloroplast degradation.
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Affiliation(s)
| | - Simona Eicke
- Department of Biology, ETH Zurich, CH-8092 Zurich, Switzerland
| | - Tabea Mettler
- Department of Biology, ETH Zurich, CH-8092 Zurich, Switzerland
- Present address: Max Planck Institute for Molecular Plant Physiology, Potsdam-Golm 14476, Germany
| | - Gaëlle Messerli
- Department of Biology, ETH Zurich, CH-8092 Zurich, Switzerland
- Present address: Johnson & Johnson Medical, CH-8957 Spreitenbach, Switzerland
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342
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Joyard J, Ferro M, Masselon C, Seigneurin-Berny D, Salvi D, Garin J, Rolland N. Chloroplast proteomics and the compartmentation of plastidial isoprenoid biosynthetic pathways. MOLECULAR PLANT 2009; 2:1154-80. [PMID: 19969518 DOI: 10.1093/mp/ssp088] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Recent advances in the proteomic field have allowed high-throughput experiments to be conducted on chloroplast samples. Many proteomic investigations have focused on either whole chloroplast or sub-plastidial fractions. To date, the Plant Protein Database (PPDB, Sun et al., 2009) presents the most exhaustive chloroplast proteome available online. However, the accurate localization of many proteins that were identified in different sub-plastidial compartments remains hypothetical. Ferro et al. (2009) went a step further into the knowledge of Arabidopsis thaliana chloroplast proteins with regards to their accurate localization within the chloroplast by using a semi-quantitative proteomic approach known as spectral counting. Their proteomic strategy was based on the accurate mass and time tags (AMT) database approach and they built up AT_CHLORO, a comprehensive chloroplast proteome database with sub-plastidial localization and curated information on envelope proteins. Comparing these two extensive databases, we focus here on about 100 enzymes involved in the synthesis of chloroplast-specific isoprenoids. Well known pathways (i.e. compartmentation of the methyl erythritol phosphate biosynthetic pathway, of tetrapyrroles and chlorophyll biosynthesis and breakdown within chloroplasts) validate the spectral counting-based strategy. The same strategy was then used to identify the precise localization of the biosynthesis of carotenoids and prenylquinones within chloroplasts (i.e. in envelope membranes, stroma, and/or thylakoids) that remains unclear until now.
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Affiliation(s)
- Jacques Joyard
- Laboratoire de Physiologie Cellulaire Végétale, UMR 5168, CEA, CNRS, INRA, Université Joseph Fourier, iRTSV, CEA-Grenoble, 38054 Grenoble-cedex 9, France
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343
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Fluorescent chlorophyll catabolites in bananas light up blue halos of cell death. Proc Natl Acad Sci U S A 2009; 106:15538-43. [PMID: 19805212 DOI: 10.1073/pnas.0908060106] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Breakdown of chlorophyll is a major contributor to the diagnostic color changes in fall leaves, and in ripening apples and pears, where it commonly provides colorless, nonfluorescent tetrapyrroles. In contrast, in ripening bananas (Musa acuminata) chlorophylls fade to give unique fluorescent catabolites (FCCs), causing yellow bananas to glow blue, when observed under UV light. Here, we demonstrate the capacity of the blue fluorescent chlorophyll catabolites to signal symptoms of programmed cell death in a plant. We report on studies of bright blue luminescent rings on the peel of very ripe bananas, which arise as halos around necrotic areas in 'senescence associated' dark spots. These dark spots appear naturally on the peel of ripe bananas and occur in the vicinity of stomata. Wavelength, space, and time resolved fluorescence measurements allowed the luminescent areas to be monitored on whole bananas. Our studies revealed an accumulation of FCCs in luminescent rings, within senescing cells undergoing the transition to dead tissue, as was observable by morphological textural cellular changes. FCCs typically are short lived intermediates of chlorophyll breakdown. In some plants, FCCs are uniquely persistent, as is seen in bananas, and can thus be used as luminescent in vivo markers in tissue undergoing senescence. While FCCs still remain to be tested for their own hypothetical physiological role in plants, they may help fill the demand for specific endogenous molecular reporters in noninvasive assays of plant senescence. Thus, they allow for in vivo studies, which provide insights into critical stages preceding cell death.
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344
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Morita R, Sato Y, Masuda Y, Nishimura M, Kusaba M. Defect in non-yellow coloring 3, an alpha/beta hydrolase-fold family protein, causes a stay-green phenotype during leaf senescence in rice. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2009; 59:940-52. [PMID: 19453447 DOI: 10.1111/j.1365-313x.2009.03919.x] [Citation(s) in RCA: 127] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Chlorophyll degradation is an important phenomenon in the senescence process. It is necessary for the degradation of certain chlorophyll-protein complexes and thylakoid membranes during leaf senescence. Mutants retaining greenness during leaf senescence are known as 'stay-green' mutants. Non-functional type stay-green mutants, which possess defects in chlorophyll degradation, retain greenness but not leaf functionality during senescence. Here, we report a new stay-green mutant in rice, nyc3. nyc3 retained a higher chlorophyll a and chlorophyll b content than the wild-type but showed a decrease in other senescence parameters during dark incubation, suggesting that it is a non-functional stay-green mutant. In addition, a small amount of pheophytin a, a chlorophyll a-derivative without Mg(2+) ions in its tetrapyrrole ring, accumulated in the senescent leaves of nyc3. nyc3 shows a similar but weaker phenotype to stay green (sgr), another non-functional stay-green mutant in rice. The chlorophyll content of nyc3 sgr double mutants at the late stage of leaf senescence was also similar to that of sgr. Linkage analysis revealed that NYC3 is located near the centromere region of chromosome 6. Map-based cloning of genes near the centromere is very difficult because of the low recombination rate; however, we overcame this problem by using ionizing radiation-induced mutant alleles harboring deletions of hundreds of kilobases. Thus, it was revealed that NYC3 encodes a plastid-localizing alpha/beta hydrolase-fold family protein with an esterase/lipase motif. The possible function of NYC3 in the regulation of chlorophyll degradation is discussed.
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Affiliation(s)
- Ryouhei Morita
- Institute of Radiation Breeding, National Institute of Agrobiological Sciences, Hitachi-ohmiya 219-2293, Japan
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345
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Yang X, Pang X, Xu L, Fang R, Huang X, Guan P, Lu W, Zhang Z. Accumulation of soluble sugars in peel at high temperature leads to stay-green ripe banana fruit. JOURNAL OF EXPERIMENTAL BOTANY 2009; 60:4051-4062. [PMID: 19700495 DOI: 10.1093/jxb/erp238] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Bananas (Musa acuminata, AAA group) fail to develop a yellow peel and stay green when ripening at temperatures >24 degrees C. The identification of the mechanisms leading to the development of stay-green ripe bananas has practical value and is helpful in revealing pathways involved in the regulation of chlorophyll (Chl) degradation. In the present study, the Chl degradation pathway was characterized and the progress of ripening and senescence was assessed in banana peel at 30 degrees C versus 20 degrees C, by monitoring relevant gene expression and ripening and senescence parameters. A marked reduction in the expression levels of the genes for Chl b reductase, SGR (Stay-green protein), and pheophorbide a oxygenase was detected for the fruit ripening at 30 degrees C, when compared with fruit at 20 degrees C, indicating that Chl degradation was repressed at 30 degrees C at various steps along the Chl catabolic pathway. The repressed Chl degradation was not due to delayed ripening and senescence, since the fruit at 30 degrees C displayed faster onset of various ripening and senescence symptoms, suggesting that the stay-green ripe bananas are of similar phenotype to type C stay-green mutants. Faster accumulation of high levels of fructose and glucose in the peel at 30 degrees C prompted investigation of the roles of soluble sugars in Chl degradation. In vitro incubation of detached pieces of banana peel showed that the pieces of peel stayed green when incubated with 150 mM glucose or fructose, but turned completely yellow in the absence of sugars or with 150 mM mannitol, at either 20 degrees C or 30 degrees C. The results suggest that accumulation of sugars in the peel induced by a temperature of 30 degrees C may be a major factor regulating Chl degradation independently of fruit senescence.
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Affiliation(s)
- Xiaotang Yang
- College of Horticulture, South China Agricultural University, Guangzhou, 510642, China
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346
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Thomas H, Huang L, Young M, Ougham H. Evolution of plant senescence. BMC Evol Biol 2009; 9:163. [PMID: 19602260 PMCID: PMC2716323 DOI: 10.1186/1471-2148-9-163] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2008] [Accepted: 07/14/2009] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Senescence is integral to the flowering plant life-cycle. Senescence-like processes occur also in non-angiosperm land plants, algae and photosynthetic prokaryotes. Increasing numbers of genes have been assigned functions in the regulation and execution of angiosperm senescence. At the same time there has been a large expansion in the number and taxonomic spread of plant sequences in the genome databases. The present paper uses these resources to make a study of the evolutionary origins of angiosperm senescence based on a survey of the distribution, across plant and microbial taxa, and expression of senescence-related genes. RESULTS Phylogeny analyses were carried out on protein sequences corresponding to genes with demonstrated functions in angiosperm senescence. They include proteins involved in chlorophyll catabolism and its control, homeoprotein transcription factors, metabolite transporters, enzymes and regulators of carotenoid metabolism and of anthocyanin biosynthesis. Evolutionary timelines for the origins and functions of particular genes were inferred from the taxonomic distribution of sequences homologous to those of angiosperm senescence-related proteins. Turnover of the light energy transduction apparatus is the most ancient element in the senescence syndrome. By contrast, the association of phenylpropanoid metabolism with senescence, and integration of senescence with development and adaptation mediated by transcription factors, are relatively recent innovations of land plants. An extended range of senescence-related genes of Arabidopsis was profiled for coexpression patterns and developmental relationships and revealed a clear carotenoid metabolism grouping, coordinated expression of genes for anthocyanin and flavonoid enzymes and regulators and a cluster pattern of genes for chlorophyll catabolism consistent with functional and evolutionary features of the pathway. CONCLUSION The expression and phylogenetic characteristics of senescence-related genes allow a framework to be constructed of decisive events in the evolution of the senescence syndrome of modern land-plants. Combining phylogenetic, comparative sequence, gene expression and morphogenetic information leads to the conclusion that biochemical, cellular, integrative and adaptive systems were progressively added to the ancient primary core process of senescence as the evolving plant encountered new environmental and developmental contexts.
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Affiliation(s)
- Howard Thomas
- IBERS, Aberystwyth University, Ceredigion, SY23 3DA, UK
| | - Lin Huang
- IBERS, Aberystwyth University, Plas Gogerddan, Aberystwyth, Ceredigion, SY23 3EB, UK
| | - Mike Young
- IBERS, Aberystwyth University, Ceredigion, SY23 3DA, UK
| | - Helen Ougham
- IBERS, Aberystwyth University, Plas Gogerddan, Aberystwyth, Ceredigion, SY23 3EB, UK
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347
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Shi DY, Liu ZX, Jin WW. [Biosynthesis, catabolism and related signal regulations of plant chlorophyll]. YI CHUAN = HEREDITAS 2009; 31:698-704. [PMID: 19586874 DOI: 10.3724/sp.j.1005.2009.00698] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Plant photosynthesis is determined by chlorophyll (Chl) metabolism, which is an important factor of determining crop yield. The genes involved in Chl biosynthesis, catabolism, and related signal regulations are numerous, and the mutation of any of them may change the pigment level, causing abnormalities in leaf color and even inducing individual death. Spontaneous or artificial mutants are necessary for functional analysis of Chl related genes. At present, Chl mutants are widely used in foundational research and production practice. This article reviews the latest research progress in this field.
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Affiliation(s)
- Dian-Yi Shi
- National Maize Improvement Center of China, Key Laboratory of Crop Genetic Improvement and Genome of Ministry of Agriculture, China Agricultural University, Beijing 100193, China.
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348
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Engqvist M, Drincovich MF, Flügge UI, Maurino VG. Two D-2-hydroxy-acid dehydrogenases in Arabidopsis thaliana with catalytic capacities to participate in the last reactions of the methylglyoxal and beta-oxidation pathways. J Biol Chem 2009; 284:25026-37. [PMID: 19586914 DOI: 10.1074/jbc.m109.021253] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Arabidopsis thaliana locus At5g06580 encodes an ortholog to Saccharomyces cerevisiae d-lactate dehydrogenase (AtD-LDH). The recombinant protein is a homodimer of 59-kDa subunits with one FAD per monomer. A substrate screen indicated that AtD-LDH catalyzes the oxidation of d- and l-lactate, d-2-hydroxybutyrate, glycerate, and glycolate using cytochrome c as an electron acceptor. AtD-LDH shows a clear preference for d-lactate, with a catalytic efficiency 200- and 2000-fold higher than that for l-lactate and glycolate, respectively, and a K(m) value for d-lactate of approximately 160 microm. Knock-out mutants showed impaired growth in the presence of d-lactate or methylglyoxal. Collectively, the data indicated that the protein is a d-LDH that participates in planta in the methylglyoxal pathway. Web-based bioinformatic tools revealed the existence of a paralogous protein encoded by locus At4g36400. The recombinant protein is a homodimer of 61-kDa subunits with one FAD per monomer. A substrate screening revealed highly specific d-2-hydroxyglutarate (d-2HG) conversion in the presence of an organic cofactor with a K(m) value of approximately 580 microm. Thus, the enzyme was characterized as a d-2HG dehydrogenase (AtD-2HGDH). Analysis of knock-out mutants demonstrated that AtD-2HGDH is responsible for the total d-2HGDH activity present in A. thaliana. Gene coexpression analysis indicated that AtD-2HGDH is in the same network as several genes involved in beta-oxidation and degradation of branched-chain amino acids and chlorophyll. It is proposed that AtD-2HGDH participates in the catabolism of d-2HG most probably during the mobilization of alternative substrates from proteolysis and/or lipid degradation.
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Affiliation(s)
- Martin Engqvist
- Botanisches Institut, Universität zu Köln, Gyrhofstrasse 15, 50931 Cologne, Germany
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349
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Hong JH, Chung G, Cowan AK. Delayed leaf senescence by exogenous lyso-phosphatidylethanolamine: towards a mechanism of action. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2009; 47:526-534. [PMID: 19167900 DOI: 10.1016/j.plaphy.2008.12.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2008] [Revised: 12/11/2008] [Accepted: 12/18/2008] [Indexed: 05/27/2023]
Abstract
Exogenous application of the lysophospholipid, lyso-phosphatidylethanolamine (LPE) is purported to delay leaf senescence in plants. However, lyso-phospholipids are well known to possess detergent-like activity and application of LPE to plant tissues might be expected to rather elicit a wound-like response and enhance senescence progression. Since phosphatidic acid (PA) accumulation and leaf cell death are a consequence of wounding, PA- and hormone-induced senescence was studied in leaf discs from Philodendron cordatum (Vell.) Kunth plants in the presence or absence of egg-derived 18:0-LPE and senescence progression quantified by monitoring both lipid peroxidation (as the change in malondialdehyde concentration), and by measuring retention of total chlorophyll (Chl(a+b)) and carotenoids (C(c+x)). Only abscisic acid (ABA) stimulated lipid peroxidation whereas ABA, 1-aminocyclopropane-1-carboxylic acid (ACC), the immediate precursor to ethylene (ETH), and 16:0-18:2-PA stimulated loss of chloroplast pigments. Results using primary alcohols as attenuators of the endogenous PA signal confirmed a role for PA as an intermediate in both ABA- and ETH-mediated senescence progression. Exogenous 18:0-LPE did not appear to influence senescence progression and was unable to reverse hormone-induced senescence progression. However, when supplied together with 16:0-18:2-PA at 1:1 (mol:mol), activity of phosphatidylglycerol (PG) hydrolase, chlorophyllase (E.C. 3.1.1.14), and progression of leaf senescence were negated. This apparent anti-senescence activity of exogenous 18:0-LPE was associated with induction of the pathogenesis-related protein, extracellular acid invertase (Ac INV, E.C. 3.2.1.26) suggesting that 18:0-LPE like 16:0-18:2-PA functions as an elicitor.
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Affiliation(s)
- Ji Heun Hong
- Biotech Institute, Glonet BU, Doosan Corporation, Yongin, South Korea
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350
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Sugishima M, Kitamori Y, Noguchi M, Kohchi T, Fukuyama K. Crystal Structure of Red Chlorophyll Catabolite Reductase: Enlargement of the Ferredoxin-Dependent Bilin Reductase Family. J Mol Biol 2009; 389:376-87. [DOI: 10.1016/j.jmb.2009.04.017] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2009] [Revised: 04/08/2009] [Accepted: 04/09/2009] [Indexed: 11/25/2022]
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