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Sample records for chloroplast differentiation annual

  1. Nitrogen control of chloroplast differentiation. Annual progress report

    SciTech Connect

    Schmidt, G.W.

    1992-07-01

    This project is directed toward understanding how the availability of nitrogen affects the accumulation of chloroplast pigments and proteins functioning in energy transduction and carbon metabolism. Molecular analyses performed with Chlamydomonas reinhardtii grown in a continuous culture system such that ammonium concentration is maintained at a low steady-state concentration so as to limit cell division. As compared to chloroplasts from cells of non-limiting nitrogen provisions, chloroplasts of N-limited cells are profoundly chlorophyll-deficient but still assimilate carbon for deposition of as starch and as storage lipids. Chlorophyll deficiency arises by limiting accumulation of appropriate nuclear-encoded mRNAs of and by depressed rates of translation of chloroplast mRNAs for apoproteins of reaction centers. Chloroplast translational effects can be partially ascribed to diminished rates of chlorophyll biosynthesis in N-limited cells, but pigment levels are not determinants for expression of the nuclear light-harvesting protein genes. Consequently, other signals that are responsive to nitrogen availability mediate transcriptional or post-transcriptional processes for accumulation of the mRNAs for LHC apoproteins and other mRNAs whose abundance is dependent upon high nitrogen levels. Conversely, limited nitrogen availability promotes accumulation of other proteins involved in carbon metabolism and oxidative electron transport in chloroplasts. Hence, thylakoids of N-limited cells exhibit enhanced chlororespiratory activities wherein oxygen serves as the electron acceptor in a pathway that involves plastoquinone and other electron carrier proteins that remain to be thoroughly characterized. Ongoing and future studies are also outlined.

  2. Nitrogen control of chloroplast development and differentiation. Annual progress report

    SciTech Connect

    Schmidt, G.W.

    1991-12-01

    The growth and development of plants and photosynthetic microorganisms is commonly limited by the availability of nitrogen. Our work concerns understanding the mechanisms by which plants and algae that are subjected to nitrogen deprivation alter the composition of photosynthetic membranes and enzymes involved in photosynthetic carbon metabolism. Toward these ends, we study biosynthetic and gene expression processes in the unicellular green alga Chlamydomonas reinhardtii which is grown in an ammonium-limited continuous culture system. We have found that the expression of nuclear genes, including those encoding for light-harvesting proteins, are severely repressed in nitrogen-limited cells whereas, in general, chloroplast protein synthesis is attenuated primarily at the level of mRNA translation. Conversely, nitrogen deprivation appears to lead to enhanced synthesis of enzymes that are involved in starch and storage lipid deposition. In addition, as a possible means by which photosynthetic electron transport activities and ATP synthesis is sustained during chronic periods of nitrogen deprivation, thylakoid membranes become enriched with components for chlororespiration. Characterization of the chlororespiratory electron transport constituents, including cytochrome complexes and NAD(P)H dehydrogenase is a major current effort. Also, we are striving to isolate the genes encoding chlororespiration proteins toward determining how they and others that are strongly responsive to nutrient availability are regulated.

  3. Nitrogen control of chloroplast differentiation

    SciTech Connect

    Schmidt, G.W.

    1994-11-01

    This project was directed toward understanding how the availability of nitrogen affects the accumulation of chloroplast pigments and proteins that function in energy transduction and carbon metabolism. The availability of this nutrient most pervasively limits plant growth and agricultural productivity but the molecular and physiological consequences of nitrogen-deficiency are poorly understood. The model system for our studies of nitrogen-dependent regulation of chloroplast differentiation is the unicellular green alga Chlamydomonas reinhardtii which is grown phototrophically in a continuous culture system. When 150 {mu}M nitrogen is provided at a dilution rate of 0.25 volumes of the growth medium per day, the cultures are sustained at a density of less than 10{sup 5} cells/ml and chlorophyll deficiency, the classical symptom of nitrogen-deficiency, becomes quite pronounced. We found that there is a concomitant loss of light-harvesting complexes and reduced levels of Photosystem II reaction center complexes while ATP synthetase and Photosystem I reaction centers are maintained at high levels. Moreover, reduced rates of chloroplast protein synthesis are due to differential effects on mRNA translation. In contrast, the deficiency of light-harvesting genes is due to marked reductions of the nuclear-encoded cab mRNAs. Although there is no significant reduction of the amounts of RuBPCase, we also detected substantial changes in the mRNA abundance of the alga`s two small subunit genes. All of the effects of nitrogen-limitation are readily reversible: greening of cells is completed within 24 hours after provision of 10 mM ammonium. During this time, the plastid translational constraints are disengaged and progressive changes in the abundance of nuclear transcripts occur, including a transient 30-fold elevation of {und cab} mRNAs.

  4. Dynamics of Chloroplast Translation during Chloroplast Differentiation in Maize.

    PubMed

    Chotewutmontri, Prakitchai; Barkan, Alice

    2016-07-01

    Chloroplast genomes in land plants contain approximately 100 genes, the majority of which reside in polycistronic transcription units derived from cyanobacterial operons. The expression of chloroplast genes is integrated into developmental programs underlying the differentiation of photosynthetic cells from non-photosynthetic progenitors. In C4 plants, the partitioning of photosynthesis between two cell types, bundle sheath and mesophyll, adds an additional layer of complexity. We used ribosome profiling and RNA-seq to generate a comprehensive description of chloroplast gene expression at four stages of chloroplast differentiation, as displayed along the maize seedling leaf blade. The rate of protein output of most genes increases early in development and declines once the photosynthetic apparatus is mature. The developmental dynamics of protein output fall into several patterns. Programmed changes in mRNA abundance make a strong contribution to the developmental shifts in protein output, but output is further adjusted by changes in translational efficiency. RNAs with prioritized translation early in development are largely involved in chloroplast gene expression, whereas those with prioritized translation in photosynthetic tissues are generally involved in photosynthesis. Differential gene expression in bundle sheath and mesophyll chloroplasts results primarily from differences in mRNA abundance, but differences in translational efficiency amplify mRNA-level effects in some instances. In most cases, rates of protein output approximate steady-state protein stoichiometries, implying a limited role for proteolysis in eliminating unassembled or damaged proteins under non-stress conditions. Tuned protein output results from gene-specific trade-offs between translational efficiency and mRNA abundance, both of which span a large dynamic range. Analysis of ribosome footprints at sites of RNA editing showed that the chloroplast translation machinery does not generally

  5. Dynamics of Chloroplast Translation during Chloroplast Differentiation in Maize

    PubMed Central

    Chotewutmontri, Prakitchai; Barkan, Alice

    2016-01-01

    Chloroplast genomes in land plants contain approximately 100 genes, the majority of which reside in polycistronic transcription units derived from cyanobacterial operons. The expression of chloroplast genes is integrated into developmental programs underlying the differentiation of photosynthetic cells from non-photosynthetic progenitors. In C4 plants, the partitioning of photosynthesis between two cell types, bundle sheath and mesophyll, adds an additional layer of complexity. We used ribosome profiling and RNA-seq to generate a comprehensive description of chloroplast gene expression at four stages of chloroplast differentiation, as displayed along the maize seedling leaf blade. The rate of protein output of most genes increases early in development and declines once the photosynthetic apparatus is mature. The developmental dynamics of protein output fall into several patterns. Programmed changes in mRNA abundance make a strong contribution to the developmental shifts in protein output, but output is further adjusted by changes in translational efficiency. RNAs with prioritized translation early in development are largely involved in chloroplast gene expression, whereas those with prioritized translation in photosynthetic tissues are generally involved in photosynthesis. Differential gene expression in bundle sheath and mesophyll chloroplasts results primarily from differences in mRNA abundance, but differences in translational efficiency amplify mRNA-level effects in some instances. In most cases, rates of protein output approximate steady-state protein stoichiometries, implying a limited role for proteolysis in eliminating unassembled or damaged proteins under non-stress conditions. Tuned protein output results from gene-specific trade-offs between translational efficiency and mRNA abundance, both of which span a large dynamic range. Analysis of ribosome footprints at sites of RNA editing showed that the chloroplast translation machinery does not generally

  6. Nitrogen control of chloroplast differentiation

    SciTech Connect

    Schmidt, G.W.

    1992-07-01

    This project is directed toward understanding how the availability of nitrogen affects the accumulation of chloroplast pigments and proteins functioning in energy transduction and carbon metabolism. Molecular analyses performed with Chlamydomonas reinhardtii grown in a continuous culture system such that ammonium concentration is maintained at a low steady-state concentration so as to limit cell division. As compared to chloroplasts from cells of non-limiting nitrogen provisions, chloroplasts of N-limited cells are profoundly chlorophyll-deficient but still assimilate carbon for deposition of as starch and as storage lipids. Chlorophyll deficiency arises by limiting accumulation of appropriate nuclear-encoded mRNAs of and by depressed rates of translation of chloroplast mRNAs for apoproteins of reaction centers. Chloroplast translational effects can be partially ascribed to diminished rates of chlorophyll biosynthesis in N-limited cells, but pigment levels are not determinants for expression of the nuclear light-harvesting protein genes. Consequently, other signals that are responsive to nitrogen availability mediate transcriptional or post-transcriptional processes for accumulation of the mRNAs for LHC apoproteins and other mRNAs whose abundance is dependent upon high nitrogen levels. Conversely, limited nitrogen availability promotes accumulation of other proteins involved in carbon metabolism and oxidative electron transport in chloroplasts. Hence, thylakoids of N-limited cells exhibit enhanced chlororespiratory activities wherein oxygen serves as the electron acceptor in a pathway that involves plastoquinone and other electron carrier proteins that remain to be thoroughly characterized. Ongoing and future studies are also outlined.

  7. Nitrogen control of chloroplast differentiation. Final report

    SciTech Connect

    Schmidt, G.W.

    1998-05-01

    This project was directed toward understanding at the physiological, biochemical and molecular levels of how photosynthetic organisms adapt to long-term nitrogen-deficiency conditions is quite incomplete even though limitation of this nutrient is the most commonly restricts plant growth and development. For our work on this problem, the unicellular green alga, Chlamydomonas reinhardtii, was grown in continuous cultures in which steady-state levels of nitrogen can be precisely controlled. N-limited cells exhibit the classical symptoms of deficiency of this nutrient, chlorosis and slow growth rates, and respond to nitrogen provision by rapid greening and chloroplast differentiation. We have addressed three aspects of this problem: (1) the regulation of pigment synthesis; (2) control of expression of nuclear genes encoding photosynthetic proteins; (3) changes in metabolic and electron transport pathways that enable sustained CO{sub 2} fixation even though they cannot be readily converted into amino and nucleic acids. For the last, principle components are: (a) enhanced mitochondrial respiratory activity intimately associated with photosynthates, and (b) the occurrence in thylakoids of a supplemental electron transport pathway that facilitates reduction of the plastoquinone pool. Together, these distinguishing features of N-limited cells are likely to enable cell survival, especially under conditions of high irradiance stress.

  8. Nitrogen control of chloroplast development and differentiation

    SciTech Connect

    Schmidt, G.W.

    1991-12-01

    The growth and development of plants and photosynthetic microorganisms is commonly limited by the availability of nitrogen. Our work concerns understanding the mechanisms by which plants and algae that are subjected to nitrogen deprivation alter the composition of photosynthetic membranes and enzymes involved in photosynthetic carbon metabolism. Toward these ends, we study biosynthetic and gene expression processes in the unicellular green alga Chlamydomonas reinhardtii which is grown in an ammonium-limited continuous culture system. We have found that the expression of nuclear genes, including those encoding for light-harvesting proteins, are severely repressed in nitrogen-limited cells whereas, in general, chloroplast protein synthesis is attenuated primarily at the level of mRNA translation. Conversely, nitrogen deprivation appears to lead to enhanced synthesis of enzymes that are involved in starch and storage lipid deposition. In addition, as a possible means by which photosynthetic electron transport activities and ATP synthesis is sustained during chronic periods of nitrogen deprivation, thylakoid membranes become enriched with components for chlororespiration. Characterization of the chlororespiratory electron transport constituents, including cytochrome complexes and NAD(P)H dehydrogenase is a major current effort. Also, we are striving to isolate the genes encoding chlororespiration proteins toward determining how they and others that are strongly responsive to nutrient availability are regulated.

  9. The workflow for quantitative proteome analysis of chloroplast development and differentiation, chloroplast mutants, and protein interactions by spectral counting.

    PubMed

    Friso, Giulia; Olinares, Paul Dominic B; van Wijk, Klaas J

    2011-01-01

    This chapter outlines a quantitative proteomics workflow using a label-free spectral counting technique. The workflow has been tested on different aspects of chloroplast biology in maize and Arabidopsis, including chloroplast mutant analysis, cell-type specific chloroplast differentiation, and the proplastid-to-chloroplast transition. The workflow involves one-dimensional SDS-PAGE of the proteomes of leaves or chloroplast subfractions, tryptic digestions, online LC-MS/MS using a mass spectrometer with high mass accuracy and duty cycle, followed by semiautomatic data processing. The bioinformatics analysis can effectively select best gene models and deals with quantification of closely related proteins; the workflow avoids overidentification of proteins and results in more accurate protein quantification. The final output includes pairwise comparative quantitative analysis, as well as hierarchical clustering for discovery of temporal and spatial patterns of protein accumulation. A brief discussion about potential pitfalls, as well as the advantages and disadvantages of spectral counting, is provided.

  10. Differential light-scattering of granal and agranal chloroplasts and their fragments.

    PubMed Central

    Faludi-Dániel, A; Bialek, G E; Horváth, G; Sz-Rózsa, Z; Gregory, R P

    1978-01-01

    Intact (class-A) granal and agranal maize chloroplasts and chloroplast fragments were examined for differential scattering of circularly polarized light (measured at 90 degrees) and c.d. (circular dichroism) (measured at 0 degrees) by using a modified spectropolarimeter with a large acceptance angle. Useful c.d. information was obtained by making corrections for scattered light. Chloroplast fragments exhibited a large and characteristic differential scattering of circularly polarized light recognized in the presence of granal chloroplasts. It is confirmed that agranal chloroplasts do not have the intense 682 nm c.d. peak that is assigned to the presence of grana. PMID:708414

  11. Functional Differentiation of Bundle Sheath and Mesophyll Maize Chloroplasts Determined by Comparative ProteomicsW⃞

    PubMed Central

    Majeran, Wojciech; Cai, Yang; Sun, Qi; van Wijk, Klaas J.

    2005-01-01

    Chloroplasts of maize (Zea mays) leaves differentiate into specific bundle sheath (BS) and mesophyll (M) types to accommodate C4 photosynthesis. Consequences for other plastid functions are not well understood but are addressed here through a quantitative comparative proteome analysis of purified M and BS chloroplast stroma. Three independent techniques were used, including cleavable stable isotope coded affinity tags. Enzymes involved in lipid biosynthesis, nitrogen import, and tetrapyrrole and isoprenoid biosynthesis are preferentially located in the M chloroplasts. By contrast, enzymes involved in starch synthesis and sulfur import preferentially accumulate in BS chloroplasts. The different soluble antioxidative systems, in particular peroxiredoxins, accumulate at higher levels in M chloroplasts. We also observed differential accumulation of proteins involved in expression of plastid-encoded proteins (e.g., EF-Tu, EF-G, and mRNA binding proteins) and thylakoid formation (VIPP1), whereas others were equally distributed. Enzymes related to the C4 shuttle, the carboxylation and regeneration phase of the Calvin cycle, and several regulators (e.g., CP12) distributed as expected. However, enzymes involved in triose phosphate reduction and triose phosphate isomerase are primarily located in the M chloroplasts, indicating that the M-localized triose phosphate shuttle should be viewed as part of the BS-localized Calvin cycle, rather than a parallel pathway. PMID:16243905

  12. Maintenance of Chloroplast Components during Chromoplast Differentiation in the Tomato Mutant Green Flesh.

    PubMed

    Cheung, A. Y.; McNellis, T.; Piekos, B.

    1993-04-01

    ripened either in the dark or in the light. These results suggest that the lesion in gf may alleviate conditions associated with chloroplast deterioration during the chloroplast-chromoplast transition in tomato ripening but has no direct effect on chromoplast differentiation per se. The ultrastructure of gf provides unequivocal evidence that, in ripening tomato, chromoplasts indeed differentiate from preexisting chloroplasts; on the other hand, chromoplast differentiation in the dark-matured and -ripened tomato fruits indicates that chromoplast development can be a process entirely independent of the chloroplasts.

  13. Differential positioning of C(4) mesophyll and bundle sheath chloroplasts: recovery of chloroplast positioning requires the actomyosin system.

    PubMed

    Kobayashi, Hiroaki; Yamada, Masahiro; Taniguchi, Mitsutaka; Kawasaki, Michio; Sugiyama, Tatsuo; Miyake, Hiroshi

    2009-01-01

    In C(4) plants, bundle sheath (BS) chloroplasts are arranged in the centripetal position or in the centrifugal position, although mesophyll (M) chloroplasts are evenly distributed along cell membranes. To examine the molecular mechanism for the intracellular disposition of these chloroplasts, we observed the distribution of actin filaments in BS and M cells of the C(4) plants finger millet (Eleusine coracana) and maize (Zea mays) using immunofluorescence. Fine actin filaments encircled chloroplasts in both cell types, and an actin network was observed adjacent to plasma membranes. The intracellular disposition of both chloroplasts in finger millet was disrupted by centrifugal force but recovered within 2 h in the dark. Actin filaments remained associated with chloroplasts during recovery. We also examined the effects of inhibitors on the rearrangement of chloroplasts. Inhibitors of actin polymerization, myosin-based activities and cytosolic protein synthesis blocked migration of chloroplasts. In contrast, a microtubule-depolymerizing drug had no effect. These results show that C(4) plants possess a mechanism for keeping chloroplasts in the home position which is dependent on the actomyosin system and cytosolic protein synthesis but not tubulin or light.

  14. Light-regulated differential expression of pea chloroplast and cytosolic fructose-1,6-bisphosphatases.

    PubMed

    Lee, S-W; Hahn, T-R

    2003-02-01

    The light-regulated differential expression of pea chloroplast and cytosolic fructose-1,6-bisphosphatases (FBPase) was investigated using enzyme activity assay, immunoblot, and Northern blot analyses. The enzyme activities of both chloroplast and cytosolic FBPases gradually increased under continuous white light illumination, although the increase in chloroplast FBPase was more drastic. Northern and immunoblot analyses also indicated that light stimulated the expression of both enzymes. Enzyme activity and the transcript levels of both enzymes gradually decreased under the dark treatment, although protein levels were unchanged for up to 24 h following the initiation of culture in the dark, indicating that reversible modifications of the enzymes may occur during the transition from light to dark (or the reverse). Light pulse experiments using blue (420 nm) and red/far-red (660/730 nm) light were carried out to analyze the photoreceptors related to the light-mediated expression of both enzymes. Expression of the chloroplast enzyme was very sensitive to red or far-red light pulses-it was induced by red light, but suppressed by far-red light pulses, as determined by enzyme activity, immunoblot, and Northern blot analyses, suggesting that red light signaling is involved in the control of chloroplast FBPase expression. However, cytosolic FBPase was virtually insensitive to blue or red/far-red light pulses in terms of enzyme activity, as determined by protein and transcript levels, indicating that cytosolic enzyme expression is not directly regulated by light signals. Instead, the expression of the cytosolic enzyme may be closely related to photosynthetic energy conversion accompanied by continuous white light irradiation.

  15. Exploring mechanisms linked to differentiation and function of dimorphic chloroplasts in the single cell C4 species Bienertia sinuspersici.

    PubMed

    Rosnow, Josh; Yerramsetty, Pradeep; Berry, James O; Okita, Thomas W; Edwards, Gerald E

    2014-01-21

    In the model single-cell C4 plant Bienertia sinuspersici, chloroplast- and nuclear-encoded photosynthetic enzymes, characteristically confined to either bundle sheath or mesophyll cells in Kranz-type C4 leaves, all occur together within individual leaf chlorenchyma cells. Intracellular separation of dimorphic chloroplasts and key enzymes within central and peripheral compartments allow for C4 carbon fixation analogous to NAD-malic enzyme (NAD-ME) Kranz type species. Several methods were used to investigate dimorphic chloroplast differentiation in B. sinuspersici. Confocal analysis revealed that Rubisco-containing chloroplasts in the central compartment chloroplasts (CCC) contained more photosystem II proteins than the peripheral compartment chloroplasts (PCC) which contain pyruvate,Pi dikinase (PPDK), a pattern analogous to the cell type-specific chloroplasts of many Kranz type NAD-ME species. Transient expression analysis using GFP fusion constructs containing various lengths of a B. sinuspersici Rubisco small subunit (RbcS) gene and the transit peptide of PPDK revealed that their import was not specific to either chloroplast type. Immunolocalization showed the rbcL-specific mRNA binding protein RLSB to be selectively localized to the CCC in B. sinuspersici, and to Rubisco-containing BS chloroplasts in the closely related Kranz species Suaeda taxifolia. Comparative fluorescence analyses were made using redox-sensitive and insensitive GFP forms, as well comparative staining using the peroxidase indicator 3,3-diaminobenzidine (DAB), which demonstrated differences in stromal redox potential, with the CCC having a more negative potential than the PCC. Both CCC RLSB localization and the differential chloroplast redox state are suggested to have a role in post-transcriptional rbcL expression.

  16. Exploring mechanisms linked to differentiation and function of dimorphic chloroplasts in the single cell C4 species Bienertia sinuspersici

    PubMed Central

    2014-01-01

    Background In the model single-cell C4 plant Bienertia sinuspersici, chloroplast- and nuclear-encoded photosynthetic enzymes, characteristically confined to either bundle sheath or mesophyll cells in Kranz-type C4 leaves, all occur together within individual leaf chlorenchyma cells. Intracellular separation of dimorphic chloroplasts and key enzymes within central and peripheral compartments allow for C4 carbon fixation analogous to NAD-malic enzyme (NAD-ME) Kranz type species. Several methods were used to investigate dimorphic chloroplast differentiation in B. sinuspersici. Results Confocal analysis revealed that Rubisco-containing chloroplasts in the central compartment chloroplasts (CCC) contained more photosystem II proteins than the peripheral compartment chloroplasts (PCC) which contain pyruvate,Pi dikinase (PPDK), a pattern analogous to the cell type-specific chloroplasts of many Kranz type NAD-ME species. Transient expression analysis using GFP fusion constructs containing various lengths of a B. sinuspersici Rubisco small subunit (RbcS) gene and the transit peptide of PPDK revealed that their import was not specific to either chloroplast type. Immunolocalization showed the rbcL-specific mRNA binding protein RLSB to be selectively localized to the CCC in B. sinuspersici, and to Rubisco-containing BS chloroplasts in the closely related Kranz species Suaeda taxifolia. Comparative fluorescence analyses were made using redox-sensitive and insensitive GFP forms, as well comparative staining using the peroxidase indicator 3,3-diaminobenzidine (DAB), which demonstrated differences in stromal redox potential, with the CCC having a more negative potential than the PCC. Conclusions Both CCC RLSB localization and the differential chloroplast redox state are suggested to have a role in post-transcriptional rbcL expression. PMID:24443986

  17. Cell-type-specific differentiation of chloroplasts in C4 plants.

    PubMed

    Majeran, Wojciech; van Wijk, Klaas J

    2009-02-01

    In leaves of C4 grasses such as maize, photosynthetic activities are partitioned between bundle-sheath and mesophyll cells, leading to increased photosynthetic yield, particularly under stress conditions. As we discuss here, recent comparative chloroplast proteome analyses in maize have shown specific adaptation to C4-cell-specific differentiation of the photosynthetic apparatus, primary and secondary metabolism and metabolite transporters, as well as the chloroplast protein homeostasis machinery. Furthermore, a novel bundle-sheath-enriched 1000-kDa NADPH dehydrogenase 'supercomplex' has been identified, and we discuss its possible role in inorganic carbon concentration. These breakthroughs provide new opportunities to further unravel C4 pathways and to increase crop productivity through metabolic engineering of C4 pathways into C3 plants, such as rice.

  18. Differential methylation of chloroplast DNA regulates maternal inheritance in a methylated mutant of Chlamydomonas

    PubMed Central

    Sager, Ruth; Grabowy, Constance

    1983-01-01

    In Chlamydomonas, the maternal inheritance of chloroplast genes correlates with the differential methylation of chloroplast DNA (chlDNA) in females (mt+) but not in males (mt-). Our previous studies have supported our methylation-restriction model in which the maternal transmission is accounted for by the differential methylation in gametes which protects female but not male chlDNA from degradation during zygote formation. In the mutant me-1 [Bolen, P. L., Grant, D. M., Swinton, D., Boynton, J. E. & Gillham, N. W. (1982) Cell 28, 335-343], chlDNA of vegetative cells of both mating types is heavily methylated even before gametogenesis; nonetheless, maternal inheritance occurs in mutants as in wild type. To investigate the mechanism of maternal inheritance in the me-1 mutant, we have compared restriction fragment patterns after agarose gel electrophoresis of chlDNAs from mutant vegetative cells and gametes with those from wild type, by using a set of 32 restriction enzymes of which 17 were methylation-sensitive in this system. We find that additional methylation occurs during gametogenesis in the mutant female (mt+) but not in the corresponding male (mt-). Thus, gamete-specific, mating-type-specific methylation occurs in the me-1 mutant as in the wild type, consistent with our methylation-restriction model. In the me-1 mutant, gametic methylation occurs on a background of vegetative cell methylation not present in wild-type cells and irrelevant to the regulation of chloroplast inheritance. Comparison of the me-1 mutation with the mat-1 mutation [Sager, R., Grabowy, C. & Sano, H. (1981) Cell 24, 41-47] provides evidence for the existence of two different chlDNA methylation control systems: mat-1, linked to the mating type locus and regulating the mating-type-specific methylation that correlates with maternal inheritance, and me-1, unlinked to the mating type locus and unrelated to the regulation of maternal inheritance. Images PMID:16593314

  19. Differential positioning of chloroplasts in C4 mesophyll and bundle sheath cells.

    PubMed

    Maai, Eri; Miyake, Hiroshi; Taniguchi, Mitsutaka

    2011-08-01

    Chloroplast photorelocation movement is extensively studied in C3 but not C4 plants. C4 plants have 2 types of photosynthetic cells: mesophyll and bundle sheath cells. Mesophyll chloroplasts are randomly distributed along cell walls, whereas bundle sheath chloroplasts are located close to the vascular tissues or mesophyll cells depending on the plant species. The cell-specific C 4 chloroplast arrangement is established during cell maturation, and is maintained throughout the life of the cell. However, only mesophyll chloroplasts can change their positions in response to environmental stresses. The migration pattern is unique to C4 plants and differs from that of C3 chloroplasts. In this mini-review, we highlight the cell-specific disposition of chloroplasts in C4 plants and discuss the possible physiological significances.

  20. Protein profiling of plastoglobules in chloroplasts and chromoplasts. A surprising site for differential accumulation of metabolic enzymes.

    PubMed

    Ytterberg, A Jimmy; Peltier, Jean-Benoit; van Wijk, Klaas J

    2006-03-01

    Plastoglobules (PGs) are oval or tubular lipid-rich structures present in all plastid types, but their specific functions are unclear. PGs contain quinones, alpha-tocopherol, and lipids and, in chromoplasts, carotenoids as well. It is not known whether PGs contain any enzymes or regulatory proteins. Here, we determined the proteome of PGs from chloroplasts of stressed and unstressed leaves of Arabidopsis (Arabidopsis thaliana) as well as from pepper (Capsicum annuum) fruit chromoplasts using mass spectrometry. Together, this showed that the proteome of chloroplast PGs consists of seven fibrillins, providing a protein coat and preventing coalescence of the PGs, and an additional 25 proteins likely involved in metabolism of isoprenoid-derived molecules (quinines and tocochromanols), lipids, and carotenoid cleavage. Four unknown ABC1 kinases were identified, possibly involved in regulation of quinone monooxygenases. Most proteins have not been observed earlier but have predicted N-terminal chloroplast transit peptides and lack transmembrane domains, consistent with localization in the PG lipid monolayer particles. Quantitative differences in PG composition in response to high light stress and degreening were determined by differential stable-isotope labeling using formaldehyde. More than 20 proteins were identified in the PG proteome of pepper chromoplasts, including four enzymes of carotenoid biosynthesis and several homologs of proteins observed in the chloroplast PGs. Our data strongly suggest that PGs in chloroplasts form a functional metabolic link between the inner envelope and thylakoid membranes and play a role in breakdown of carotenoids and oxidative stress defense, whereas PGs in chromoplasts are also an active site for carotenoid conversions.

  1. Choice of tracks, microtubules and/or actin filaments for chloroplast photo-movement is differentially controlled by phytochrome and a blue light receptor.

    PubMed

    Sato, Y; Wada, M; Kadota, A

    2001-01-01

    Light induced chloroplast movement has been studied as a model system for photoreception and actin microfilament (MF)-based intracellular motilities in plants. Chloroplast photo-accumulation and -avoidance movement is mediated by phytochrome as well as blue light (BL) receptor in the moss Physcomitrella patens. Here we report the discovery of an involvement of a microtubule (MT)-based system in addition to an MF-based system in photorelocation of chloroplasts in this moss. In the dark, MTs provided tracks for rapid movement of chloroplasts in a longitudinal direction and MFs contributed the tracks for slow movement in any direction. We found that phytochrome responses utilized only the MT-based system, while BL responses had an alternative way of moving, either along MTs or MFs. MT-based systems were mediated by both photoreceptors, but chloroplasts showed movements with different velocity and pattern between them. No apparent difference in the behavior of chloroplast movement between the accumulation and avoidance movement was detected in phytochrome responses or BL responses, except for the direction of the movement. The results presented here demonstrate that chloroplasts use both MTs and MFs for motility and that phytochrome and a BL receptor control directional photo-movement of chloroplasts through the differential regulation of these motile systems.

  2. Differential positioning of C4 mesophyll and bundle sheath chloroplasts: aggregative movement of C4 mesophyll chloroplasts in response to environmental stresses.

    PubMed

    Yamada, Masahiro; Kawasaki, Michio; Sugiyama, Tatsuo; Miyake, Hiroshi; Taniguchi, Mitsutaka

    2009-10-01

    In C(4) plants, mesophyll (M) chloroplasts are randomly distributed along the cell walls, while bundle sheath (BS) chloroplasts are typically located in either a centripetal or centrifugal position. We investigated whether these intracellular positions are affected by environmental stresses. When mature leaves of finger millet (Eleusine coracana) were exposed to extremely high intensity light, most M chloroplasts aggregatively re-distributed to the BS side, whereas the intracellular arrangement of BS chloroplasts was unaffected. Compared with the homologous light-avoidance movement of M chloroplasts in C(3) plants, it requires extremely high light (3,000-4,000 micromol m(-2) s(-1)) and responds more slowly (distinctive movement observed in 1 h). The high light-induced movement of M chloroplasts was also observed in maize (Zea mays), another C(4) species, but with a distinct pattern of redistribution along the sides of anticlinal walls, analogous to C(3) plants. The aggregative movement of M chloroplasts occurred at normal light intensities (250-500 micromol m(-2) s(-1)) in response to environmental stresses, such as drought, salinity and hyperosmosis. Moreover, the re-arrangement of M chloroplasts was observed in field-grown C(4) plants when exposed to mid-day sunlight, but also under midsummer drought conditions. The migration of M chloroplasts was controlled by actin filaments and also induced in a light-dependent fashion upon incubation with ABA, which may be the physiological signal transducer. Together these results suggest that M and BS cells of C(4) plants have different mechanisms controlling intracellular chloroplast positioning, and that the aggregative movement of C(4) M chloroplasts is thought to be a protective response under environmental stress conditions.

  3. Phosphoinositides play differential roles in regulating phototropin1- and phototropin2-mediated chloroplast movements in Arabidopsis.

    PubMed

    Aggarwal, Chhavi; Labuz, Justyna; Gabryś, Halina

    2013-01-01

    Phototropins are UVA/blue-light receptors involved in controlling the light-dependent physiological responses which serve to optimize the photosynthetic activity of plants and promote growth. The phototropin-induced phosphoinositide (PI) metabolism has been shown to be essential for stomatal opening and phototropism. However, the role of PIs in phototropin-induced chloroplast movements remains poorly understood. The aim of this work is to determine which PI species are involved in the control of chloroplast movements in Arabidopsis and the nature of their involvement. We present the effects of the inactivation of phospholipase C (PLC), PI3-kinase (PI3K) and PI4-kinase (PI4K) on chloroplast relocations in Arabidopsis. The inhibition of the phosphatidylinositol 4,5-bisphospahte [PI(4,5)P2]-PLC pathway, using neomycin and U73122, suppressed the phot2-mediated chloroplast accumulation and avoidance responses, without affecting movement responses controlled by phot1. On the other hand, PI3K and PI4K activities are more restricted to phot1- and phot2-induced weak-light responses. The inactivation of PI3K and PI4K by wortmannin and LY294002 severely affected the weak blue-light-activated accumulation response but had little effect on the strong blue-light-activated avoidance response. The inhibitory effect observed with PI metabolism inhibitors is, at least partly, due to a disturbance in Ca(2+) ((c)) signaling. Using the transgenic aequorin system, we show that the application of these inhibitors suppresses the blue-light-induced transient Ca(2+) ((c)) rise. These results demonstrate the importance of PIs in chloroplast movements, with the PI(4,5)P2-PLC pathway involved in phot2 signaling while PI3K and PI4K are required for the phot1- and phot2-induced accumulation response. Our results suggest that these PIs modulate cytosolic Ca(2+) signaling during movements.

  4. Transposon-induced nuclear mutations that alter chloroplast gene expression. Annual report, September 1, 1991--August 31, 1992

    SciTech Connect

    Barkan, A.

    1992-12-31

    The goal of this project is to use mutant phenotypes as a guide to nuclear genes that determine the timing and localization of chloroplast development The immediate goals are to identify nuclear mutants with defects in chloroplast gene expression from maize lines harboring active Mu transposons; characterize their phenotypes to determine the precise defect in gene expression; clone several of the most interesting mutations by exploiting the transposon tag; and use the clones to further define the roles of these genes in modulating chloroplast gene expression. Three mutants were described earlier that had global defects in chloroplast gene expression. We have found that two of these mutations are allelic. Both alleles have global defects in chloroplast translation initiation, as revealed by the failure to assemble chloroplast mRNAs into polysomes. We have isolated and characterized three new mutants from Mu lines that have novel defects in chloroplast RNA metabolism. We are now ready to begin the task of cloning several of these genes, by using the Mu transposon tag.

  5. The Chloroplast Min System Functions Differentially in Two Specific Nongreen Plastids in Arabidopsis thaliana

    PubMed Central

    Wang, Peng; Zhang, Jie; Su, Jianbin; Wang, Peng; Liu, Jun; Liu, Bing; Feng, Dongru; Wang, Jinfa; Wang, Hongbin

    2013-01-01

    The nongreen plastids, such as etioplasts, chromoplasts, etc., as well as chloroplasts, are all derived from proplastids in the meristem. To date, the Min system members in plants have been identified as regulators of FtsZ-ring placement, which are essential for the symmetrical division of chloroplasts. However, the regulation of FtsZ-ring placement in nongreen plastids is poorly understood. In this study, we investigated the division site placement of nongreen plastids by examining the etioplasts as representative in Arabidopsis Min system mutants. Surprisingly, the shape and number of etioplasts in cotyledons of arc3, arc11 and mcd1 mutants were similar to that observed in wild-type plants, whereas arc12 and parc6 mutants exhibited enlarged etioplasts that were reduced in number. In order to examine nongreen plastids in true leaves, we silenced the ALB3 gene in these Min system mutant backgrounds to produce immature chloroplasts without the thylakoidal network using virus induced gene silencing (VIGS). Interestingly, consistent with our observations in etioplasts, enlarged and fewer nongreen plastids were only detected in leaves of parc6 (VIGS-ALB3) and arc12 (VIGS-ALB3) plants. Further, the FtsZ-ring assembled properly at the midpoint in nongreen plastids of arc3, arc11 and mcd1 (VIGS-ALB3) plants, but organized into multiple rings in parc6 (VIGS-ALB3) and presented fragmented filaments in arc12 (VIGS-ALB3) plants, suggesting that division site placement in nongreen plastids requires fewer components of the plant Min system. Taken together, these results suggest that division site placement in nongreen plastids is different from that in chloroplasts. PMID:23936263

  6. Differential Subplastidial Localization and Turnover of Enzymes Involved in Isoprenoid Biosynthesis in Chloroplasts

    PubMed Central

    Perello, Catalina; Llamas, Ernesto; Burlat, Vincent; Ortiz-Alcaide, Miriam; Phillips, Michael A.; Pulido, Pablo; Rodriguez-Concepcion, Manuel

    2016-01-01

    Plastidial isoprenoids are a diverse group of metabolites with roles in photosynthesis, growth regulation, and interaction with the environment. The methylerythritol 4-phosphate (MEP) pathway produces the metabolic precursors of all types of plastidial isoprenoids. Proteomics studies in Arabidopsis thaliana have shown that all the enzymes of the MEP pathway are localized in the plastid stroma. However, immunoblot analysis of chloroplast subfractions showed that the first two enzymes of the pathway, deoxyxylulose 5-phosphate synthase (DXS) and reductoisomerase (DXR), can also be found in non-stromal fractions. Both transient and stable expression of GFP-tagged DXS and DXR proteins confirmed the presence of the fusion proteins in distinct subplastidial compartments. In particular, DXR-GFP was found to accumulate in relatively large vesicles that could eventually be released from chloroplasts, presumably to be degraded by an autophagy-independent process. Together, we propose that protein-specific mechanisms control the localization and turnover of the first two enzymes of the MEP pathway in Arabidopsis chloroplasts. PMID:26919668

  7. Differential Subplastidial Localization and Turnover of Enzymes Involved in Isoprenoid Biosynthesis in Chloroplasts.

    PubMed

    Perello, Catalina; Llamas, Ernesto; Burlat, Vincent; Ortiz-Alcaide, Miriam; Phillips, Michael A; Pulido, Pablo; Rodriguez-Concepcion, Manuel

    2016-01-01

    Plastidial isoprenoids are a diverse group of metabolites with roles in photosynthesis, growth regulation, and interaction with the environment. The methylerythritol 4-phosphate (MEP) pathway produces the metabolic precursors of all types of plastidial isoprenoids. Proteomics studies in Arabidopsis thaliana have shown that all the enzymes of the MEP pathway are localized in the plastid stroma. However, immunoblot analysis of chloroplast subfractions showed that the first two enzymes of the pathway, deoxyxylulose 5-phosphate synthase (DXS) and reductoisomerase (DXR), can also be found in non-stromal fractions. Both transient and stable expression of GFP-tagged DXS and DXR proteins confirmed the presence of the fusion proteins in distinct subplastidial compartments. In particular, DXR-GFP was found to accumulate in relatively large vesicles that could eventually be released from chloroplasts, presumably to be degraded by an autophagy-independent process. Together, we propose that protein-specific mechanisms control the localization and turnover of the first two enzymes of the MEP pathway in Arabidopsis chloroplasts.

  8. Tobacco VDL Gene Encodes a Plastid DEAD Box RNA Helicase and Is Involved in Chloroplast Differentiation and Plant Morphogenesis

    PubMed Central

    Wang, Yingchun; Duby, Geoffrey; Purnelle, Bénédicte; Boutry, Marc

    2000-01-01

    The recessive nuclear vdl (for variegated and distorted leaf) mutant of tobacco was obtained by T-DNA insertion and characterized by variegated leaves and abnormal roots and flowers. Affected leaf tissues were white and distorted, lacked palisadic cells, and contained undifferentiated plastids. The variegation was due to phenotypic, rather than genetic, instability. Genomic and cDNA clones were obtained for both the mutant and wild-type VDL alleles. Three transcripts, resulting from alternate intron splicing or polyadenylation, were found for the wild type. The transcripts potentially encode a set of proteins (53, 19, and 15 kD) sharing the same N-terminal region that contains a chloroplast transit peptide capable of importing the green fluorescent protein into chloroplasts. The predicted 53-kD product belongs to the DEAD box RNA helicase family. In the homozygous vdl mutant, T-DNA insertion resulted in accumulation of the shortest transcript and the absence of the RNA helicase–encoding transcript. Genetic transformation of the homozygous mutant by the 53-kD product–encoding cDNA fully restored the wild-type phenotype. These data suggest that a plastid RNA helicase controls early plastid differentiation and plant morphogenesis. PMID:11090214

  9. Expression of antisense or sense RNA of an ankyrin repeat-containing gene blocks chloroplast differentiation in arabidopsis.

    PubMed Central

    Zhang, H; Scheirer, D C; Fowle, W H; Goodman, H M

    1992-01-01

    The Arabidopsis AKR gene that encodes a protein with four ankyrin repeats (a 33-amino acid motif that appears in the 89K domain of the human protein ankyrin) was isolated and characterized. A short sequence outside the ankyrin repeats is similar to that of the protein of the Drosophila muscle segment homeobox (msh) gene. The expression of the AKR gene is light dependent, and transgenic Arabidopsis plants with two or more copies of an antisense or sense AKR construct became chlorotic in a developmentally regulated manner. The chlorotic phenotype was genetically transmitted to the next generation, although most chlorotic plants produced much less seed. Reduced presence of thylakoid membranes and loss of grana are found in the plastids of chlorotic leaves, indicating that antisense or sense AKR has blocked chloroplast differentiation. This study indicates the importance of ankyrin repeat-containing proteins, not only in yeast and animals, but in plants as well. PMID:1281700

  10. In vitro transcription and DNA binding characteristics of chloroplast and etioplast extracts from mustard (Sinapis alba) indicate differential usage of the psbA promoter.

    PubMed Central

    Eisermann, A; Tiller, K; Link, G

    1990-01-01

    The psbA gene which is differentially expressed in vivo in chloroplasts and etioplasts has an unusual promoter, containing both prokaryotic-type '-35' and '-10' elements and a sequence motif that resembles the nuclear TATA box. Single base pair substitutions were introduced into the mustard psbA promoter and the mutants were tested in transcription and DNA binding experiments, using extracts from either chloroplasts or etioplasts. Positions within the '-35' region appear to play an essential role in the chloroplast but not in the etioplast system. Altering the first or second position of the 'TATA box'-like region led to decreased psbA in vitro transcription in either plastid extract. These two mutations, however, did not affect binding of extracts to the (linear) psbA promoter fragment in gel retardation assays. Fragments carrying two other plastid promoters effectively competed psbA promoter binding of the etioplast extract, but more weakly that of the chloroplast extract. Lambda exonuclease mapping shows that the 5' border of the binding region is more upstream with the etioplast than with the chloroplast system, whereas the 3' border appears to be the same. Hence, protein(s) of the two plastid types seem to interact differently with the mustard psbA promoter in vitro and perhaps also in vivo. Images Fig. 3. Fig. 4. Fig. 5. Fig. 6. Fig. 7. PMID:2249659

  11. Transposon-induced nuclear mutations that alter chloroplast gene expression. Annual report, September 1, 1992--April 15, 1993

    SciTech Connect

    Barkan, A.

    1993-04-20

    The goal of this project is to use mutant phenotypes as a guide to nuclear genes that control the timing and cell-type specificity of chloroplast gene expression. Studies are being conducted with nuclear mutants of maize that are defective in the biogenesis or translation of chloroplast mRNAs. Currently studies are focused on two nuclear mutants with specific and unique lesions in chloroplast RNA processing (crp mutants). Crp1 mutants (formerly called hcf136) fail to accumulate the cytochrome f/b6 complex. The protein loss is due to a defect in the metabolism of transcripts encoding the petB and petD gene products, two subunits of the missing complex. Mutant seedlings lack the monocistronic petB and petD MRNAS, which both arise in nominal plants by endonucleolytic cleavage of the polycistronic primary transcript of the psbB gene cluster. Precursor mRNAs accumulate normally in crp1, indicating that its defect is due either to a failure to cleave the precursors, or a failure to stabilize the fully processed mRNAs. We are interested in both the biochemistry of this site-specific RNA processing and in the role of the processing in generating translatable mRNAs. To address the latter, we are quantifying the rates of synthesis of the petB and petD gene products with the goal of determining whether the missing transcripts are more efficiently translated than their precursors. To address the biochemistry of the defect in RNA metabolism, the crp1 gene is being cloned via the transposon tag. crp2 (formerly called hcf142) lacks the predominant mRNA encoding petA, but appears to be otherwise unimpaired in chloroplast RNA metabolism. The precise role of crp2 in synthesizing or stabilizing the petA mRNA is being investigated through biochemical studies.

  12. Chloroplast movement.

    PubMed

    Wada, Masamitsu

    2013-09-01

    Chloroplast movement is important for plant survival under high light and for efficient photosynthesis under low light. This review introduces recent knowledge on chloroplast movement and shows how to analyze the responses and the moving mechanisms, potentially inspiring research in this field. Avoidance from the strong light is mediated by blue light receptor phototropin 2 (phot2) plausibly localized on the chloroplast envelop and accumulation at the week light-irradiated area is mediated by phot1 and phot2 localized on the plasma membrane. Chloroplasts move by chloroplast actin (cp-actin) filaments that must be polymerized by Chloroplast Unusual Positioning1 (CHUP1) at the front side of moving chloroplast. To understand the signal transduction pathways and the mechanism of chloroplast movement, that is, from light capture to motive force-generating mechanism, various methods should be employed based on the various aspects. Observation of chloroplast distribution pattern under different light condition by fixed cell sectioning is somewhat an old-fashioned technique but the most basic and important way. However, most importantly, precise chloroplast behavior during and just after the induction of chloroplast movement by partial cell irradiation using an irradiator with either low light or strong light microbeam should be recorded by time lapse photographs under infrared light and analyzed. Recently various factors involved in chloroplast movement, such as cp-actin filaments and CHUP1, could be traced in Arabidopsis transgenic lines with fluorescent protein tags under a confocal laser scanning microscope (CLSM) and/or a total internal reflection fluorescence microscope (TIRFM). These methods are listed and their advantages and disadvantages are evaluated. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  13. Transient expression of βC1 protein differentially regulates host genes related to stress response, chloroplast and mitochondrial functions

    PubMed Central

    2010-01-01

    Background Geminiviruses are emerging plant pathogens that infect a wide variety of crops including cotton, cassava, vegetables, ornamental plants and cereals. The geminivirus disease complex consists of monopartite begomoviruses that require betasatellites for the expression of disease symptoms. These complexes are widespread throughout the Old World and cause economically important diseases on several crops. A single protein encoded by betasatellites, termed βC1, is a suppressor of gene silencing, inducer of disease symptoms and is possibly involved in virus movement. Studies of the interaction of βC1 with hosts can provide useful insight into virus-host interactions and aid in the development of novel control strategies. We have used the differential display technique to isolate host genes which are differentially regulated upon transient expression of the βC1 protein of chili leaf curl betasatellite (ChLCB) in Nicotiana tabacum. Results Through differential display analysis, eight genes were isolated from Nicotiana tabacum, at two and four days after infitration with βC1 of ChLCB, expressed under the control of the Cauliflower mosaic virus 35S promoter. Cloning and sequence analysis of differentially amplified products suggested that these genes were involved in ATP synthesis, and acted as electron carriers for respiration and photosynthesis processes. These differentially expressed genes (DEGs) play an important role in plant growth and development, cell protection, defence processes, replication mechanisms and detoxification responses. Kegg orthology based annotation system analysis of these DEGs demonstrated that one of the genes, coding for polynucleotide nucleotidyl transferase, is involved in purine and pyrimidine metabolic pathways and is an RNA binding protein which is involved in RNA degradation. Conclusion βC1 differentially regulated genes are mostly involved in chloroplast and mitochondrial functions. βC1 also increases the expression of those

  14. Differentiation of Populus species using chloroplast single nucleotide polymorphism (SNP) markers--essential for comprehensible and reliable poplar breeding.

    PubMed

    Schroeder, H; Hoeltken, A M; Fladung, M

    2012-03-01

    Within the genus Populus several species belonging to different sections are cross-compatible. Hence, high numbers of interspecies hybrids occur naturally and, additionally, have been artificially produced in huge breeding programmes during the last 100 years. Therefore, determination of a single poplar species, used for the production of 'multi-species hybrids' is often difficult, and represents a great challenge for the use of molecular markers in species identification. Within this study, over 20 chloroplast regions, both intergenic spacers and coding regions, have been tested for their ability to differentiate different poplar species using 23 already published barcoding primer combinations and 17 newly designed primer combinations. About half of the published barcoding primers yielded amplification products, whereas the new primers designed on the basis of the total sequenced cpDNA genome of Populus trichocarpa Torr. & Gray yielded much higher amplification success. Intergenic spacers were found to be more variable than coding regions within the genus Populus. The highest discrimination power of Populus species was found in the combination of two intergenic spacers (trnG-psbK, psbK-psbl) and the coding region rpoC. In barcoding projects, the coding regions matK and rbcL are often recommended, but within the genus Populus they only show moderate variability and are not efficient in species discrimination.

  15. Chloroplast movement.

    PubMed

    Wada, Masamitsu; Kagawa, Takatoshi; Sato, Yoshikatsu

    2003-01-01

    The study of chloroplast movement made a quantum leap at the beginning of the twenty-first century. Research based on reverse-genetic approaches using targeted mutants has brought new concepts to this field. One of the most exciting findings has been the discovery of photoreceptors for both accumulation and avoidance responses in Arabidopsis and in the fern Adiantum. Evidence for the adaptive advantage of chloroplast avoidance movements in plant survival has also been found. Additional discoveries include mechano-stress-induced chloroplast movement in ferns and mosses, and microtubule-mediated chloroplast movement in the moss Physcomitrella. The possible ecological significance of chloroplast movement is discussed in the final part of this review.

  16. Differential replication of two chloroplast genome forms in heteroplasmic Chlamydomonas reinhardtii gametes contributes to alternative inheritance patterns.

    PubMed

    Nishimura, Yoshiki; Stern, David B

    2010-08-01

    Two mechanisms for chloroplast DNA replication have been revealed through the study of an unusual heteroplasmic strain of the green alga Chlamydomonas reinhardtii. Heteroplasmy is a state in which more than one genome type occurs in a mitochondrion or chloroplast. The Chlamydomonas strain spa19 bears two distinct chloroplast genomes, termed PS+ and PS-. PS+ genomes predominate and are stably maintained in vegetative cells, despite their lack of known replication origins. In sexual crosses with spa19 as the mating type plus parent, however, PS+ genomes are transmitted in only approximately 25% of tetrads, whereas the PS- genomes are faithfully inherited in all progeny. In this research, we have explored the mechanism underlying this biased uniparental inheritance. We show that the relative reduction and dilution of PS+ vs. PS- genomes takes place during gametogenesis. Bromodeoxyuridine labeling, followed by immunoprecipitation and PCR, was used to compare replication activities of PS+ and PS- genomes. We found that the replication of PS+ genomes is specifically suppressed during gametogenesis and germination of zygospores, a phenomenon that also was observed when spa19 cells were treated with rifampicin, an inhibitor of the chloroplast RNA polymerase. Furthermore, when bromodeoxyuridine incorporation was compared at 11 sites within the chloroplast genome between vegetative cells, gametes, and rifampicin-treated cells by quantitative PCR, we found that incorporation was often reduced at the same sites in gametes that were also sensitive to rifampicin treatment. We conclude that a transcription-mediated form of DNA replication priming, which may be downregulated during gametogenesis, is indispensable for robust maintenance of PS+ genomes. These results highlight the potential for chloroplast genome copy number regulation through alternative replication strategies.

  17. Differential Replication of Two Chloroplast Genome Forms in Heteroplasmic Chlamydomonas reinhardtii Gametes Contributes to Alternative Inheritance Patterns

    PubMed Central

    Nishimura, Yoshiki; Stern, David B.

    2010-01-01

    Two mechanisms for chloroplast DNA replication have been revealed through the study of an unusual heteroplasmic strain of the green alga Chlamydomonas reinhardtii. Heteroplasmy is a state in which more than one genome type occurs in a mitochondrion or chloroplast. The Chlamydomonas strain spa19 bears two distinct chloroplast genomes, termed PS+ and PS−. PS+ genomes predominate and are stably maintained in vegetative cells, despite their lack of known replication origins. In sexual crosses with spa19 as the mating type plus parent, however, PS+ genomes are transmitted in only ∼25% of tetrads, whereas the PS− genomes are faithfully inherited in all progeny. In this research, we have explored the mechanism underlying this biased uniparental inheritance. We show that the relative reduction and dilution of PS+ vs. PS− genomes takes place during gametogenesis. Bromodeoxyuridine labeling, followed by immunoprecipitation and PCR, was used to compare replication activities of PS+ and PS− genomes. We found that the replication of PS+ genomes is specifically suppressed during gametogenesis and germination of zygospores, a phenomenon that also was observed when spa19 cells were treated with rifampicin, an inhibitor of the chloroplast RNA polymerase. Furthermore, when bromodeoxyuridine incorporation was compared at 11 sites within the chloroplast genome between vegetative cells, gametes, and rifampicin-treated cells by quantitative PCR, we found that incorporation was often reduced at the same sites in gametes that were also sensitive to rifampicin treatment. We conclude that a transcription-mediated form of DNA replication priming, which may be downregulated during gametogenesis, is indispensable for robust maintenance of PS+ genomes. These results highlight the potential for chloroplast genome copy number regulation through alternative replication strategies. PMID:20519744

  18. Synthetic chloroplasts

    SciTech Connect

    Calvin, M.

    1980-06-01

    The principal function of the chloroplast is to capture solar quanta and to store them in some stable form. We are in the process of trying to construct a totally synthetic system that would simulate some of the reactions of the two photosystems which occur in natural chloroplasts. Toward this end, we have demonstrated a number of the reactions required in separated systems. We have shown that it is possible to transfer electrons across an insulating membrane barrier with a surfactant photosensitizer. Others have shown, and we have confirmed, that it is possible to collect the two electrons necessary for the generation of molecular hydrogen on a heterogeneous catalyst suspended in water and similarly to collect the four holes on another heterogeneous catalyst suspended in water for the generation of molecular oxygen. A synthesis of some of these molecular catalysts for both these purposes is underway, with some partial success. When these partial reactions are assembled in a system, the resulting synthetic chloroplasts will not resemble the natural entity in detailed construction as they will contain no protein.

  19. Differential responses of double petal and multi petal jasmine to shading: I. Photosynthetic characteristics and chloroplast ultrastructure.

    PubMed

    Deng, Yanming; Li, Congcong; Shao, Qingsong; Ye, Xiaoqing; She, Jianming

    2012-06-01

    A double petal (DP) and a multi petal (MP) type jasmine (Jasminum sambac Ait.) growth and flowering was known largely affected by different levels of irradiance. Here, our objective was to determine the effects of shade on photosynthesis related characteristics and chloroplast ultrastructure of these two types. In both types, net photosynthetic rate (Pn), stomatal conductance (g(s)) and transpiration rate increased with decreasing irradiance from 100% to 20%, while both maximum and variable fluorescence showed a steady increase, and photochemical and nonphotochemical quenching indexes declined. At each conducted time, chlorophyll a, b and carotenoids contents in DP type shaded leaves increased whereas those in MP type decreased at 5% irradiance (considered as extreme shade). The maximum photochemical efficiency of photosystem II of DP plants showed subtle changes but that of MP plants declined by shading thereafter 21 days of treatment. Observation of chloroplast ultrastructure showed its best development in the leaves of DP and MP types mostly from 50% to 20% irradiance (considered as weak and moderate shade, respectively). At each shade treatment, Pn, g(s) and water use efficiency of DP-jasmine were always higher than those of MP-jasmine, thus the shade tolerance ability of the former was higher than that of the latter. The results showed that full sunlight and 5% natural irradiance caused photoinhibition and light deficiency of jasmine plants respectively, and modulating chloroplast development by the more numbers of thylakoids and grana to contain more photosynthetic pigments is an important shade tolerance mechanism of DP type. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  20. Darkness affects differentially the expression of plastid-encoded genes and delays the senescence-induced down-regulation of chloroplast transcription in cotyledons of Cucurbita pepo L. (Zucchini).

    PubMed

    Mishev, Kiril; Dimitrova, Anna; Ananiev, Evguéni D

    2011-01-01

    In contrast to differentiated leaves, the regulatory mechanisms of chloroplast gene expression in darkened cotyledons have not been elucidated. Although some results have been reported indicating accelerated senescence in Arabidopsis upon reillumination, the capacity of cotyledons to recover after dark stress remains unclear. We analysed the effect of two-days dark stress, applied locally or at the whole-plant level, on plastid gene expression in zucchini cotyledons. Our results showed that in the dark the overall chloroplast transcription rate was much more inhibited than the nuclear run-on transcription. While the activities of the plastid-encoded RNA polymerase (PEP) and nuclear RNA polymerase II were strongly reduced, the activities of the nuclear-encoded plastid RNA polymerase (NEP) and nuclear RNA polymerase I were less affected. During recovery upon reillumination, chloroplast transcription in the cotyledons was strongly stimulated (3-fold) compared with the naturally senescing controls, suggesting delayed senescence. Northern blot and dot blot analyses of the expression of key chloroplast-encoded photosynthetic genes showed that in contrast to psbA, which remained almost unaffected, both the transcription rate and mRNA content of psaB and rbcL were substantially decreased.

  1. DNA-based differentiation of the Ecuadorian cocoa types CCN-51 and Arriba based on sequence differences in the chloroplast genome.

    PubMed

    Herrmann, Luise; Haase, Ilka; Blauhut, Maike; Barz, Nadine; Fischer, Markus

    2014-12-17

    Two cocoa types, Arriba and CCN-51, are being cultivated in Ecuador. With regard to the unique aroma, Arriba is considered a fine cocoa type, while CCN-51 is a bulk cocoa because of its weaker aroma. Because it is being assumed that Arriba is mixed with CCN-51, there is an interest in the analytical differentiation of the two types. Two methods to identify CCN-51 adulterations in Arriba cocoa were developed on the basis of differences in the chloroplast DNA. On the one hand, a different repeat of the sequence TAAAG in the inverted repeat region results in a different length of amplicons for the two cocoa types, which can be detected by agarose gel electrophoresis, capillary gel electrophoresis, and denaturing high-performance liquid chromatography. On the other hand, single nucleotide polymorphisms (SNPs) between the CCN-51 and Arriba sequences represent restriction sites, which can be used for restriction fragment length polymorphism analysis. A semi-quantitative analysis based on these SNPs is feasible. A method for an exact quantitation based on these results is not realizable. These sequence variations were confirmed for a comprehensive cultivar collection of Arriba and CCN-51, for both bean and leaf samples.

  2. Non-invasive, whole-plant imaging of chloroplast movement and chlorophyll fluorescence reveals photosynthetic phenotypes independent of chloroplast photorelocation defects in chloroplast division mutants.

    PubMed

    Dutta, Siddhartha; Cruz, Jeffrey A; Jiao, Yuhua; Chen, Jin; Kramer, David M; Osteryoung, Katherine W

    2015-10-01

    Leaf chloroplast movement is thought to optimize light capture and to minimize photodamage. To better understand the impact of chloroplast movement on photosynthesis, we developed a technique based on the imaging of reflectance from leaf surfaces that enables continuous, high-sensitivity, non-invasive measurements of chloroplast movement in multiple intact plants under white actinic light. We validated the method by measuring photorelocation responses in Arabidopsis chloroplast division mutants with drastically enlarged chloroplasts, and in phototropin mutants with impaired photorelocation but normal chloroplast morphology, under different light regimes. Additionally, we expanded our platform to permit simultaneous image-based measurements of chlorophyll fluorescence and chloroplast movement. We show that chloroplast division mutants with enlarged, less-mobile chloroplasts exhibit greater photosystem II photodamage than is observed in the wild type, particularly under fluctuating high levels of light. Comparison between division mutants and the severe photorelocation mutant phot1-5 phot2-1 showed that these effects are not entirely attributable to diminished photorelocation responses, as previously hypothesized, implying that altered chloroplast morphology affects other photosynthetic processes. Our dual-imaging platform also allowed us to develop a straightforward approach to correct non-photochemical quenching (NPQ) calculations for interference from chloroplast movement. This correction method should be generally useful when fluorescence and reflectance are measured in the same experiments. The corrected data indicate that the energy-dependent (qE) and photoinhibitory (qI) components of NPQ contribute differentially to the NPQ phenotypes of the chloroplast division and photorelocation mutants. This imaging technology thus provides a platform for analyzing the contributions of chloroplast movement, chloroplast morphology and other phenotypic attributes to the

  3. Abscisic acid represses the transcription of chloroplast genes*

    PubMed Central

    Yamburenko, Maria V.; Zubo, Yan O.; Börner, Thomas

    2013-01-01

    Numerous studies have shown effects of abscisic acid (ABA) on nuclear genes encoding chloroplast-localized proteins. ABA effects on the transcription of chloroplast genes, however, have not been investigated yet thoroughly. This work, therefore, studied the effects of ABA (75 μM) on transcription and steady-state levels of transcripts in chloroplasts of basal and apical segments of primary leaves of barley (Hordeum vulgare L.). Basal segments consist of young cells with developing chloroplasts, while apical segments contain the oldest cells with mature chloroplasts. Exogenous ABA reduced the chlorophyll content and caused changes of the endogenous concentrations not only of ABA but also of cytokinins to different extents in the basal and apical segments. It repressed transcription by the chloroplast phage-type and bacteria-type RNA polymerases and lowered transcript levels of most investigated chloroplast genes drastically. ABA did not repress the transcription of psbD and a few other genes and even increased psbD mRNA levels under certain conditions. The ABA effects on chloroplast transcription were more pronounced in basal vs. apical leaf segments and enhanced by light. Simultaneous application of cytokinin (22 μM 6-benzyladenine) minimized the ABA effects on chloroplast gene expression. These data demonstrate that ABA affects the expression of chloroplast genes differentially and points to a role of ABA in the regulation and coordination of the activities of nuclear and chloroplast genes coding for proteins with functions in photosynthesis. PMID:24078671

  4. Abscisic acid represses the transcription of chloroplast genes.

    PubMed

    Yamburenko, Maria V; Zubo, Yan O; Vanková, Radomíra; Kusnetsov, Victor V; Kulaeva, Olga N; Börner, Thomas

    2013-11-01

    Numerous studies have shown effects of abscisic acid (ABA) on nuclear genes encoding chloroplast-localized proteins. ABA effects on the transcription of chloroplast genes, however, have not been investigated yet thoroughly. This work, therefore, studied the effects of ABA (75 μM) on transcription and steady-state levels of transcripts in chloroplasts of basal and apical segments of primary leaves of barley (Hordeum vulgare L.). Basal segments consist of young cells with developing chloroplasts, while apical segments contain the oldest cells with mature chloroplasts. Exogenous ABA reduced the chlorophyll content and caused changes of the endogenous concentrations not only of ABA but also of cytokinins to different extents in the basal and apical segments. It repressed transcription by the chloroplast phage-type and bacteria-type RNA polymerases and lowered transcript levels of most investigated chloroplast genes drastically. ABA did not repress the transcription of psbD and a few other genes and even increased psbD mRNA levels under certain conditions. The ABA effects on chloroplast transcription were more pronounced in basal vs. apical leaf segments and enhanced by light. Simultaneous application of cytokinin (22 μM 6-benzyladenine) minimized the ABA effects on chloroplast gene expression. These data demonstrate that ABA affects the expression of chloroplast genes differentially and points to a role of ABA in the regulation and coordination of the activities of nuclear and chloroplast genes coding for proteins with functions in photosynthesis.

  5. Classification and differentiation of the genus Peganum indigenous to China based on chloroplast trnL-F and psbA-trnH sequences and seed coat morphology.

    PubMed

    Zhao, T; Wang, Z-T; Branford-White, C J; Xu, H; Wang, C-H

    2011-11-01

    The genus Peganum (Zygophyllaceae) consists of six species and one subspecies; three of which are distributed in China, P. harmala Linn, P. nigellastrum Bunge and P. multisectum (Maxim.) Bobr. A probable new or intermediate species, Peganum sp., has been suggested in the wild in northwest China. Traditional classification in genus Peganum has focused on hairs on the plant surface. In this study, seed coat characteristics of Peganum species were investigated using light and scanning electron microscopy, demonstrating clear differences in morphology between species. In addition, DNA sequence data from two sequences (chloroplast: trnL-F, psbA-trnH) were used to differentiate Peganum sp. and study polygenetic relationships. Diversity in DNA sequences among Peganum species was found, with inter-specific sequence divergence ranging from 0.6% to 5.6% in psbA-trnH, and 0.0% to 1.8% in trnL-F. The variations within species were low: from 0.0% to 0.4% in psbA-trnH and 0.0% to 0.4% in trnL-F. Therefore, Peganum species can now be easily identified as separate entities based on variations in DNA sequences. Phylogenetic trees were constructed from the combined data set for the two gene fragments, and the results indicate that Peganum sp. is monophyletic and sister to P. harmala and P. nigellastrum, while P. multisectum is also monophyletic. DNA data further confirmed that P. multisectum is an independent species and that a new species, Peganum sp., exists within the genus Peganum growing wild in China.

  6. Endogenous nitric oxide generation in protoplast chloroplasts.

    PubMed

    Tewari, Rajesh Kumar; Prommer, Judith; Watanabe, Masami

    2013-01-01

    KEY MESSAGE : NO generation is studied in the protoplast chloroplasts. NO, ONOO ( - ) and ROS (O ( 2 ) ( - ) and H ( 2 ) O ( 2 ) ) are generated in chloroplasts. Nitric oxide synthase-like protein appears to be involved in NO generation. Nitric oxide stimulates chlorophyll biosynthesis and chloroplast differentiation. The present study was conducted to better understand the process of NO generation in the leaf chloroplasts and protoplasts. NO, peroxynitrite and superoxide anion were investigated in the protoplasts and isolated chloroplasts using specific dyes, confocal laser scanning and light microscopy. The level of NO was highest after protoplast isolation and subsequently decreased during culture. Suppression of NO signal in the presence of PTIO, suggests that diaminofluorescein-2 diacetate (DAF-2DA) detected NO. Detection of peroxynitrite, a reaction product of NO and superoxide anion, further suggests NO generation. Moreover, generation of NO and peroxynitrite in the chloroplasts of wild-type Arabidopsis and their absence or weak signals in the leaf-derived protoplasts of Atnoa1 mutants confirmed the reactivity of DAF-2DA and aminophenyl fluorescein to NO and peroxynitrite, respectively. Isolated chloroplasts also showed signal of NO. Suppression of NO signal in the presence of 100 μM nitric oxide synthase inhibitors [L-NNA, Nω-nitro-L-arginine and PBIT, S,S'-1,3-phenylene-bis(1,2-ethanediyl)-bis-isothiourea] revealed that nitric oxide synthase-like system is involved in NO synthesis. Suppression of NO signal in the protoplasts isolated in the presence of cycloheximide suggests de novo synthesis of NO generating protein during the process of protoplast isolation. Furthermore, the lack of inhibition of NO production by sodium tungstate (250 μM) and inhibition by L-NNA, and PBIT suggest involvement NOS-like protein, but not nitrate reductase, in NO generation in the leaf chloroplasts and protoplasts.

  7. Differential Annual Movement Patterns in a Migratory Species: Effects of Experience and Sexual Maturation

    PubMed Central

    Jorge, Paulo E.; Sowter, David; Marques, Paulo A. M.

    2011-01-01

    Some animals migrate long distances to exploit important seasonal food resources in the northern regions of the northern hemisphere, whilst avoiding winter starvation. Changes in the individual's age and navigational skills are likely to affect migration, which in turn influences the geographic distribution of individuals. Processes such as sexual maturation and navigational abilities are affected by age, and age is thus a key factor in understanding migration patterns and differences in distribution ranges. In the present study, we investigated the effects of age on the geographic distribution of a population of Lesser Black-backed Gulls Larus fuscus throughout its annual cycle, by analyzing a dataset of 19,096 records from 10,000 color-ringed gulls. In contrast to previous assumptions, the results showed that gulls were geographically segregated by age throughout the entire annual cycle, rather than showing a geographic age-related cline only in the wintering areas. This asymmetric distribution results from a reduction in the annual range of sexually mature gulls, and the differential distribution of mature and immature individuals (mature birds remained in more northern areas, compared to immature birds, throughout the annual cycle). Furthermore, although immature gulls travelled longer distances than adults, they initiated their fall migration with short movements, in contrast to adults that migrated using longer movements. The effects identified in this study explain the non-homogenous distribution of populations throughout the annual cycle, with wide implications for the development of effective human health policies and/or wildlife management strategies. PMID:21799853

  8. Differential annual movement patterns in a migratory species: effects of experience and sexual maturation.

    PubMed

    Jorge, Paulo E; Sowter, David; Marques, Paulo A M

    2011-01-01

    Some animals migrate long distances to exploit important seasonal food resources in the northern regions of the northern hemisphere, whilst avoiding winter starvation. Changes in the individual's age and navigational skills are likely to affect migration, which in turn influences the geographic distribution of individuals. Processes such as sexual maturation and navigational abilities are affected by age, and age is thus a key factor in understanding migration patterns and differences in distribution ranges. In the present study, we investigated the effects of age on the geographic distribution of a population of Lesser Black-backed Gulls Larus fuscus throughout its annual cycle, by analyzing a dataset of 19,096 records from 10,000 color-ringed gulls. In contrast to previous assumptions, the results showed that gulls were geographically segregated by age throughout the entire annual cycle, rather than showing a geographic age-related cline only in the wintering areas. This asymmetric distribution results from a reduction in the annual range of sexually mature gulls, and the differential distribution of mature and immature individuals (mature birds remained in more northern areas, compared to immature birds, throughout the annual cycle). Furthermore, although immature gulls travelled longer distances than adults, they initiated their fall migration with short movements, in contrast to adults that migrated using longer movements. The effects identified in this study explain the non-homogenous distribution of populations throughout the annual cycle, with wide implications for the development of effective human health policies and/or wildlife management strategies.

  9. Auxin and chloroplast movements.

    PubMed

    Eckstein, Aleksandra; Krzeszowiec, Weronika; Waligórski, Piotr; Gabryś, Halina

    2016-03-01

    Auxin is involved in a wide spectrum of physiological processes in plants, including responses controlled by the blue light photoreceptors phototropins: phototropic bending and stomatal movement. However, the role of auxin in phototropin-mediated chloroplast movements has never been studied. To address this question we searched for potential interactions between auxin and the chloroplast movement signaling pathway using different experimental approaches and two model plants, Arabidopsis thaliana and Nicotiana tabacum. We observed that the disturbance of auxin homeostasis by shoot decapitation caused a decrease in chloroplast movement parameters, which could be rescued by exogenous auxin application. In several cases, the impairment of polar auxin transport, by chemical inhibitors or in auxin carrier mutants, had a similar negative effect on chloroplast movements. This inhibition was not correlated with changes in auxin levels. Chloroplast relocations were also affected by the antiauxin p-chlorophenoxyisobutyric acid and mutations in genes encoding some of the elements of the SCF(TIR1)-Aux/IAA auxin receptor complex. The observed changes in chloroplast movement parameters are not prominent, which points to a modulatory role of auxin in this process. Taken together, the obtained results suggest that auxin acts indirectly to regulate chloroplast movements, presumably by regulating gene expression via the SCF(TIR1)-Aux/IAA-ARF pathway. Auxin does not seem to be involved in controlling the expression of phototropins. © 2015 Scandinavian Plant Physiology Society.

  10. Purification of intact chloroplasts from Arabidopsis and spinach leaves by isopycnic centrifugation.

    PubMed

    Seigneurin-Berny, Daphné; Salvi, Daniel; Joyard, Jacques; Rolland, Norbert

    2008-09-01

    Chloroplasts are plant-specific organelles. They are the site of photosynthesis but also of many other essential metabolic pathways, such as syntheses of amino acids, vitamins, lipids, and pigments. This unit describes the isolation and purification of chloroplasts from Arabidopsis and spinach leaves. Differential centrifugation is first used to obtain a suspension enriched in chloroplasts (crude chloroplasts extract). In a second step, Percoll density gradient centrifugation is used to recover pure and intact chloroplasts. The Basic Protocol describes the purification of chloroplasts from Arabidopsis leaves. This small flowering plant is now widely used as a model organism in plant biology as it offers important advantages for basic research in genetics and molecular biology. The Alternate Protocol describes the purification of chloroplasts from spinach leaves. Spinach, easily available all through the year, remains a model of choice for the large-scale preparation of pure chloroplasts with a high degree of intactness.

  11. Activation of polyphenol oxidase of chloroplasts.

    PubMed

    Tolbert, N E

    1973-02-01

    Polyphenol oxidase of leaves is located mainly in chloroplasts isolated by differential or sucrose density gradient centrifugation. This activity is part of the lamellar structure that is not lost on repeated washing of the plastids. The oxidase activity was stable during prolonged storage of the particles at 4 C or -18 C. The Km (dihydroxyphenylalanine) for spinach leaf polyphenol oxidase was 7 mm by a spectrophotometric assay and 2 mm by the manometric assay. Polyphenol oxidase activity in the leaf peroxisomal fraction, after isopycnic centrifugation on a linear sucrose gradient, did not coincide with the peroxisomal enzymes but was attributed to proplastids at nearly the same specific density.Plants were grouped by the latency properties for polyphenol oxidase in their isolated chloroplasts. In a group including spinach, Swiss chard, and beet leaves the plastids immediately after preparation from fresh leaves required a small amount of light for maximal rates of oxidation of dihydroxyphenylalanine. Polyphenol oxidase activity in the dark or light increased many fold during aging of these chloroplasts for 1 to 5 days. Soluble polyphenol oxidase of the cytoplasm was not so stimulated. Chloroplasts prepared from stored leaves were also much more active than from fresh leaves. Maximum rates of dihydroxyphenylalanine oxidation were 2 to 6 mmoles x mg(-1) chlorophyll x hr(-1). Equal stimulation of latent polyphenol oxidase in fresh or aged chloroplasts in this group was obtained by either light, an aged trypsin digest, 3-(4-chlorophenyl)-1, 1-dimethylurea, or antimycin A. A variety of other treatments did not activate or had little effect on the oxidase, including various peptides, salts, detergents, and other proteolytic enzymes.Activation of latent polyphenol oxidase in spinach chloroplasts by trypsin amounted to as much as 30-fold. The trypsin activation occurred even after the trypsin had been treated with 10% trichloroacetic acid, 1.0 n HCl or boiled for 30

  12. Activation of Polyphenol Oxidase of Chloroplasts 1

    PubMed Central

    Tolbert, N. E.

    1973-01-01

    Polyphenol oxidase of leaves is located mainly in chloroplasts isolated by differential or sucrose density gradient centrifugation. This activity is part of the lamellar structure that is not lost on repeated washing of the plastids. The oxidase activity was stable during prolonged storage of the particles at 4 C or —18 C. The Km (dihydroxyphenylalanine) for spinach leaf polyphenol oxidase was 7 mm by a spectrophotometric assay and 2 mm by the manometric assay. Polyphenol oxidase activity in the leaf peroxisomal fraction, after isopycnic centrifugation on a linear sucrose gradient, did not coincide with the peroxisomal enzymes but was attributed to proplastids at nearly the same specific density. Plants were grouped by the latency properties for polyphenol oxidase in their isolated chloroplasts. In a group including spinach, Swiss chard, and beet leaves the plastids immediately after preparation from fresh leaves required a small amount of light for maximal rates of oxidation of dihydroxyphenylalanine. Polyphenol oxidase activity in the dark or light increased many fold during aging of these chloroplasts for 1 to 5 days. Soluble polyphenol oxidase of the cytoplasm was not so stimulated. Chloroplasts prepared from stored leaves were also much more active than from fresh leaves. Maximum rates of dihydroxyphenylalanine oxidation were 2 to 6 mmoles × mg−1 chlorophyll × hr−1. Equal stimulation of latent polyphenol oxidase in fresh or aged chloroplasts in this group was obtained by either light, an aged trypsin digest, 3-(4-chlorophenyl)-1, 1-dimethylurea, or antimycin A. A variety of other treatments did not activate or had little effect on the oxidase, including various peptides, salts, detergents, and other proteolytic enzymes. Activation of latent polyphenol oxidase in spinach chloroplasts by trypsin amounted to as much as 30-fold. The trypsin activation occurred even after the trypsin had been treated with 10% trichloroacetic acid, 1.0 n HCl or boiled for 30

  13. Betaine synthesis in chenopods: localization in chloroplasts

    SciTech Connect

    Hanson, A.D.; May A.M.; Grumet, R.; Bode, J.; Jamieson, G.C.; Rhodes, D.

    1985-06-01

    Plants from several families (Chenopodiaceae, Gramineae, Compositae) accumulate betaine (glycine betaine) in response to salt or water stress via the pathway: choline betainal (betaine aldehyde) betaine. Betaine accumulation is probably a metabolic adaptation to stress. Intact protoplasts from leaves of spinach (Spinacia oleracea) oxidized ( UC)choline to betainal and betaine, as did protoplast lysates. Upon differential centrifugation, the ( UC)choline-oxidizing activity of lysates sedimented with chloroplasts. Chloroplasts purified from protoplast lysates by a Percoll cushion procedure retained strong ( UC)choline-oxidizing activity, although the proportion of the intermediate, ( UC)betainal, in the reaction products was usually higher than for protoplasts. Isolated chloroplasts also readily oxidized ( UC)betainal to betaine. Light increased the oxidation of both ( UC)choline and ( UC)betainal by isolated chloroplasts. Similar results were obtained with another chenopod (Beta vulgaris) but not with pea (Pisum sativum), a species that accumulates no betaine. The chloroplast site for betaine synthesis in chenopods contrasts with the mitochondrial site in mammals.

  14. Longevity of guard cell chloroplasts in falling leaves: implication for stomatal function and cellular aging

    SciTech Connect

    Zeiger, E.; Schwartz, A.

    1982-11-12

    Guard cell chloroplasts in senescing leaves from 12 species of perennial trees and three species of annual plants survived considerably longer than their mesophyll counterparts. In Ginkgo biloba, stomata from yellow leaves opened during the day and closed at night; guard cell chloroplasts from these leaves showed fluorescence transients associated with electron transport and photophosphorylation. These findings indicate that guard cell chloroplasts are highly conserved throughout the life-span of the leaf and that leaves retain stomatal control during senescence.

  15. Oxidative folding in chloroplasts.

    PubMed

    Kieselbach, Thomas

    2013-07-01

    Disulfide-bonded proteins in chloroplasts from green plants exist in the envelope and the thylakoid membrane, and in the stroma and the lumen. The formation of disulfide bonds in proteins is referred to as oxidative folding and is linked to the import and folding of chloroplast proteins as well as the assembly and repair of thylakoid complexes. It is also important in the redox regulation of enzymes and signal transfer. Green-plant chloroplasts contain enzymes that can form and isomerize disulfide bonds in proteins. In Arabidopsis thaliana, four proteins are identified that are relevant for the catalysis of disulfide bond formation in chloroplast proteins. The proteins' low quantum yield of Photosystem II 1 (LQY1, At1g75690) and snowy cotyledon 2 (SCO2, At3g19220) exhibits protein disulfide isomerase activity and is suggested to function in the assembly and repair of Photosystem II (PSII), and the biogenesis of thylakoids in cotyledons, respectively. The thylakoid-located Lumen thiol oxidoreductase 1 (LTO1, At4g35760) can catalyze the formation of the disulfide bond of the extrinsic PsbO protein of PSII. In addition, the stroma-located protein disulfide isomerase PDIL1-3 (At3g54960) may have a role in oxidative folding. Research on oxidative folding in chloroplasts plants is in an early stage and little is known about the mechanisms of disulfide bond formation in chloroplast proteins. The close link between the import and folding of chloroplast proteins suggests that Hsp93, a component of the inner envelope's import apparatus, may have co-chaperones that can catalyze disulfide bond formation in newly imported proteins.

  16. Automatic Chloroplast Movement Analysis.

    PubMed

    Johansson, Henrik; Zeidler, Mathias

    2016-01-01

    In response to low or high intensities of light, the chloroplasts in the mesophyll cells of the leaf are able to increase or decrease their exposure to light by accumulating at the upper and lower sides or along the side walls of the cell respectively. This movement, regulated by the phototropin blue light photoreceptors phot1 and phot2, results in a decreased or increased transmission of light through the leaf. This way the plant is able to optimize harvesting of the incoming light or avoid damage caused by excess light. Here we describe a method that indirectly measures the movement of chloroplasts by taking advantage of the resulting change in leaf transmittance. By using a microplate reader, quantitative measurements of chloroplast accumulation or avoidance can be monitored over time, for multiple samples with relatively little hands-on time.

  17. Chloroplast RNA polymerases: Role in chloroplast biogenesis.

    PubMed

    Börner, Thomas; Aleynikova, Anastasia Yu; Zubo, Yan O; Kusnetsov, Victor V

    2015-09-01

    Plastid genes are transcribed by two types of RNA polymerase in angiosperms: the bacterial type plastid-encoded RNA polymerase (PEP) and one (RPOTp in monocots) or two (RPOTp and RPOTmp in dicots) nuclear-encoded RNA polymerase(s) (NEP). PEP is a bacterial-type multisubunit enzyme composed of core subunits (coded for by the plastid rpoA, rpoB, rpoC1 and rpoC2 genes) and additional protein factors (sigma factors and polymerase associated protein, PAPs) encoded in the nuclear genome. Sigma factors are required by PEP for promoter recognition. Six different sigma factors are used by PEP in Arabidopsis plastids. NEP activity is represented by phage-type RNA polymerases. Only one NEP subunit has been identified, which bears the catalytic activity. NEP and PEP use different promoters. Many plastid genes have both PEP and NEP promoters. PEP dominates in the transcription of photosynthesis genes. Intriguingly, rpoB belongs to the few genes transcribed exclusively by NEP. Both NEP and PEP are active in non-green plastids and in chloroplasts at all stages of development. The transcriptional activity of NEP and PEP is affected by endogenous and exogenous factors. This article is part of a Special Issue entitled: Chloroplast Biogenesis. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Chloroplast and nuclear photorelocation movements

    PubMed Central

    WADA, Masamitsu

    2016-01-01

    Chloroplasts move toward weak light to increase photosynthetic efficiency, and migrate away from strong light to protect chloroplasts from photodamage and eventual cell death. These chloroplast behaviors were first observed more than 100 years ago, but the underlying mechanism has only recently been identified. Ideal plant materials, such as fern gametophytes for photobiological and cell biological approaches, and Arabidopsis thaliana for genetic analyses, have been used along with sophisticated methods, such as partial cell irradiation and time-lapse video recording under infrared light to study chloroplast movement. These studies have revealed precise chloroplast behavior, and identified photoreceptors, other relevant protein components, and novel actin filament structures required for chloroplast movement. In this review, our findings regarding chloroplast and nuclear movements are described. PMID:27840388

  19. Chloroplasts in anther endothecium of Zea mays (Poaceae).

    PubMed

    Murphy, Katherine M; Egger, Rachel L; Walbot, Virginia

    2015-11-01

    Although anthers of Zea mays, Oryza sativa, and Arabidopsis thaliana have been studied intensively using genetic and biochemical analyses in the past 20 years, few updates to anther anatomical and ultrastructural descriptions have been reported. For example, no transmission electron microscopy (TEM) images of the premeiotic maize anther have been published. Here we report the presence of chloroplasts in maize anthers. TEM imaging, electron acceptor photosynthesis assay, in planta photon detection, microarray analysis, and light and fluorescence microscopy were used to investigate the presence of chloroplasts in the maize anther. Most cells of the maize subepidermal endothecium have starch-containing chloroplasts that do not conduct measurable photosynthesis in vitro. The maize anther contains chloroplasts in most subepidermal, endothecial cells. Although maize anthers receive sufficient light to photosynthesize in vivo and the maize anther transcribes >96% of photosynthesis-associated genes found in the maize leaf, no photosynthetic light reaction activity was detected in vitro. The endothecial cell layer should no longer be defined as a complete circle viewed transversely in anther lobes, because chloroplasts are observed only in cells directly beneath the epidermis and not those adjacent to the connective tissue. We propose that chloroplasts be a defining characteristic of differentiated endothecial cells and that nonsubepidermal endothecial cells that lack chloroplasts be defined as a separate cell type, the interendothecium. © 2015 Botanical Society of America.

  20. Isolation, chromosomal localization, and differential expression of mitochondrial manganese superoxide dismutase and chloroplastic copper/zinc superoxide dismutase genes in wheat.

    PubMed

    Wu, G; Wilen, R W; Robertson, A J; Gusta, L V

    1999-06-01

    Superoxide dismutase (SOD) gene expression was investigated to elucidate its role in drought and freezing tolerance in spring and winter wheat (Triticum aestivum). cDNAs encoding chloroplastic Cu/ZnSODs and mitochondrial MnSODs were isolated from wheat. MnSOD and Cu/ZnSOD genes were mapped to the long arms of the homologous group-2 and -7 chromosomes, respectively. Northern blots indicated that MnSOD genes were drought inducible and decreased after rehydration. In contrast, Cu/ZnSOD mRNA was not drought inducible but increased after rehydration. In both spring and winter wheat seedlings exposed to 2 degrees C, MnSOD transcripts attained maximum levels between 7 and 49 d. Transcripts of Cu/ZnSOD mRNA were detected sooner in winter than in spring wheat; however, they disappeared after 21 d of acclimation. Transcripts of both classes of SOD genes increased during natural acclimation in both spring and winter types. Exposure of fully hardened plants to three nonlethal freeze-thaw cycles resulted in Cu/Zn mRNA accumulation; however, MnSOD mRNA levels declined in spring wheat but remained unchanged in winter wheat. The results of the dehydration and freeze-thaw-cycle experiments suggest that winter wheat has evolved a more effective stress-repair mechanism than spring wheat.

  1. A tRNA gene mapping within the chloroplast rDNA cluster is differentially expressed during the development of Daucus carota.

    PubMed Central

    Manna, F; Massardo, D R; Wolf, K; Luccarini, G; Carlomagno, M S; Rivellini, F; Alifano, P; Del Giudice, L

    1994-01-01

    In vivo analysis of expression of the chloroplast rDNA cluster during somatic embryogenesis of Daucus carota (D.carota) was performed by Northern-blot analysis with different DNA probes, spanning both the 16S rRNA gene, the 16S-23S rRNA spacer, which contains the two mosaic tRNA genes tRNA(Ile) and tRNA(Ala), and the region upstream of the 16S rRNA gene, where a tRNA(Val) maps. We show that expression both of the spacer tRNAs tRNA(Ile) and tRNA(Ala) is not significantly regulated during development whereas the amount of the transcript corresponding to tRNA(Val) is not detectable during early embryonic stages and progressively accumulates during late phases. Multiple transcription start sites have been identified upstream of the tRNA(Val) gene by S1 mapping analysis, which are activated late during the embryogenesis. These data indicate that developmental control mechanisms act on plastid gene expression during embryogenesis in carrot. Images PMID:8202376

  2. Genome origin, historical hybridization and genetic differentiation in Anthosachne australasica (Triticeae; Poaceae), inferred from chloroplast rbcL, trnH-psbA and nuclear Acc1 gene sequences.

    PubMed

    Sha, Li-Na; Fan, Xing; Wang, Xiao-Li; Dong, Zhen-Zhen; Zeng, Jian; Zhang, Hai-Qin; Kang, Hou-Yang; Wang, Yi; Liao, Jin-Qiu; Zhou, Yong-Hong

    2017-01-01

    Anthosachne Steudel is a group of allopolyploid species that was derived from hexaploidization between the Asian StY genome Roegneria entity and the Australasia W genome Australopyrum species. Polyploidization and apomixis contribute to taxonomic complexity in Anthosachne Here, a study is presented on the phylogeny and evolutionary history of Anthosachne australasica The aims are to demonstrate the process of polyploidization events and to explore the differentiation patterns of the St genome following geographic isolation. Chloroplast rbcL and trnH-psbA and nuclear Acc1 gene sequences of 60 Anthosachne taxa and nine Roegneria species were analysed with those of 33 diploid taxa representing 20 basic genomes in Triticeae. The phylogenetic relationships were reconstructed. A time-calibrated phylogeny was generated to estimate the evolutionary history of A. australasica Nucleotide diversity patterns were used to assess the divergence within A. australasica and between Anthosachne and its putative progenitors. Three homoeologous copies of the Acc1 sequences from Anthosachne were grouped with the Acc1 sequences from Roegneria, Pseudoroegneria, Australopyrum, Dasypyrum and Peridictyon The chloroplast sequences of Anthosachne were clustered with those from Roegneria and Pseudoroegneria Divergence time for Anthosachne was dated to 4·66 million years ago (MYA). The level of nucleotide diversity in Australasian Anthosachne was higher than that in continental Roegneria A low level of genetic differentiation within the A. australasica complex was found. Anthosachne originated from historical hybridization between Australopyrum species and a Roegneria entity colonized from Asia to Australasia via South-east Asia during the late Miocene. The St lineage served as the maternal donor during the speciation of Anthosachne A contrasting pattern of population genetic structure exists in the A. australasica complex. Greater diversity in island Anthosachne compared with continental

  3. Transcriptional coordination between leaf cell differentiation and chloroplast development established by TCP20 and the subgroup Ib bHLH transcription factors.

    PubMed

    Andriankaja, Megan E; Danisman, Selahattin; Mignolet-Spruyt, Lorin F; Claeys, Hannes; Kochanke, Irina; Vermeersch, Mattias; De Milde, Liesbeth; De Bodt, Stefanie; Storme, Veronique; Skirycz, Aleksandra; Maurer, Felix; Bauer, Petra; Mühlenbock, Per; Van Breusegem, Frank; Angenent, Gerco C; Immink, Richard G H; Inzé, Dirk

    2014-06-01

    The establishment of the photosynthetic apparatus during chloroplast development creates a high demand for iron as a redox metal. However, iron in too high quantities becomes toxic to the plant, thus plants have evolved a complex network of iron uptake and regulation mechanisms. Here, we examined whether four of the subgroup Ib basic helix-loop-helix transcription factors (bHLH38, bHLH39, bHLH100, bHLH101), previously implicated in iron homeostasis in roots, also play a role in regulating iron metabolism in developing leaves. These transcription factor genes were strongly up-regulated during the transition from cell proliferation to expansion, and thus sink-source transition, in young developing leaves of Arabidopsis thaliana. The four subgroup Ib bHLH genes also showed reduced expression levels in developing leaves of plants treated with norflurazon, indicating their expression was tightly linked to the onset of photosynthetic activity in young leaves. In addition, we provide evidence for a mechanism whereby the transcriptional regulators SAC51 and TCP20 antagonistically regulate the expression of these four subgroup Ib bHLH genes. A loss-of-function mutant analysis also revealed that single mutants of bHLH38, bHLH39, bHLH100, and bHLH101 developed smaller rosettes than wild-type plants in soil. When grown in agar plates with reduced iron concentration, triple bhlh39 bhlh100 bhlh101 mutant plants were smaller than wild-type plants. However, measurements of the iron content in single and multiple subgroup Ib bHLH genes, as well as transcript profiling of iron response genes during early leaf development, do not support a role for bHLH38, bHLH39, bHLH100, and bHLH101 in iron homeostasis during early leaf development.

  4. [Chloroplast Deg proteases].

    PubMed

    Grabsztunowicz, Magda; Luciński, Robert; Baranek, Małgorzata; Sikora, Bogna; Jackowski, Grzegorz

    2011-01-01

    For some chloroplast proteases ATP binding and hydrolysis is not necessary for their catalytic activity, most probably because even strongly unfolded substrates may penetrate their catalytic chamber. Deg1, 2, 5 and 8 are the best known of Arabidopsis thaliana ATP- independent chloroplast proteases, encoded by orthologues of genes coding for DegP, DegQ and DegS proteases of Escherichia coli. Current awareness in the area of structure and functions of chloroplast Degs is much more limited vs the one about their bacterial counterparts. Deg5 and Deg8 form a catalytic heterododecamer which is loosely attached to luminal side of thylakoid membrane. The complex catalyses--supported by Deg1 and one of FtsH proteases--the degradation of PsbA damaged due to plant exposition to elevated irradiance and thus these protease are of key importance for the plants' sensitivity to photoinhibition. Deg2 role in the disposal of damaged PsbA has not been elucidated. Recombinant Deg1 may degrade PsbO and plastocyanin in vitro but it is not clear whether this reaction is performed in vivo as well.

  5. Immunofluorescent quantitation of chloroplast proteins.

    PubMed

    Leech, R M; Marrison, J L

    1996-12-01

    Using scanning light microscopy software to detect and measure immunofluorescence in leaf sections Rubisco concentration in situ in chloroplasts has been accurately determined throughout development. The fluorescence measurements were calibrated by comparison with values for Rubisco accumulation obtained from rocket immuno-electrophoresis profiles of soluble protein from isolated cells and from chloroplasts using a purified sample of Rubisco as the standard. It has been shown that in situ immunofluorescence can be used for cytoquantitation of proteins within individual chloroplasts to a sensitivity of 1fg and also for the comparison of the protein levels in adjacent chloroplasts and cells. Several important applications of this new technique are discussed.

  6. Multiplexed fragaria chloroplast genome sequencing

    Treesearch

    W. Njuguna; A. Liston; R. Cronn; N.V. Bassil

    2010-01-01

    A method to sequence multiple chloroplast genomes using ultra high throughput sequencing technologies was recently described. Complete chloroplast genome sequences can resolve phylogenetic relationships at low taxonomic levels and identify informative point mutations and indels. The objective of this research was to sequence multiple Fragaria...

  7. Chloroplast ribosomes and protein synthesis.

    PubMed Central

    Harris, E H; Boynton, J E; Gillham, N W

    1994-01-01

    Consistent with their postulated origin from endosymbiotic cyanobacteria, chloroplasts of plants and algae have ribosomes whose component RNAs and proteins are strikingly similar to those of eubacteria. Comparison of the secondary structures of 16S rRNAs of chloroplasts and bacteria has been particularly useful in identifying highly conserved regions likely to have essential functions. Comparative analysis of ribosomal protein sequences may likewise prove valuable in determining their roles in protein synthesis. This review is concerned primarily with the RNAs and proteins that constitute the chloroplast ribosome, the genes that encode these components, and their expression. It begins with an overview of chloroplast genome structure in land plants and algae and then presents a brief comparison of chloroplast and prokaryotic protein-synthesizing systems and a more detailed analysis of chloroplast rRNAs and ribosomal proteins. A description of the synthesis and assembly of chloroplast ribosomes follows. The review concludes with discussion of whether chloroplast protein synthesis is essential for cell survival. PMID:7854253

  8. Controversy on chloroplast origins.

    PubMed

    Lockhart, P J; Penny, D; Hendy, M D; Howe, C J; Beanland, T J; Larkum, A W

    1992-04-20

    Controversy exists over the origins of photosynthetic organelles in that contradictory trees arise from different sequence, biochemical and ultrastructural data sets. We propose a testable hypothesis which explains this inconsistency as a result of the differing GC contents of sequences. We report that current methods of tree reconstruction tend to group sequences with similar GC contents irrespective of whether the similar GC content is due to common ancestry or is independently acquired. Nuclear encoded sequences (high GC) give different trees from chloroplast encoded sequences (low GC). We find that current data is consistent with the hypothesis of multiple origins for photosynthetic organelles and single origins for each type of light harvesting complex.

  9. From bacteria to chloroplasts: evolution of the chloroplast SRP system.

    PubMed

    Ziehe, Dominik; Dünschede, Beatrix; Schünemann, Danja

    2017-05-01

    Chloroplasts derive from a prokaryotic symbiont that lost most of its genes during evolution. As a result, the great majority of chloroplast proteins are encoded in the nucleus and are posttranslationally imported into the organelle. The chloroplast genome encodes only a few proteins. These include several multispan thylakoid membrane proteins which are synthesized on thylakoid-bound ribosomes and cotranslationally inserted into the membrane. During evolution, ancient prokaryotic targeting machineries were adapted and combined with novel targeting mechanisms to facilitate post- and cotranslational protein transport in chloroplasts. This review focusses on the chloroplast signal recognition particle (cpSRP) protein transport system, which has been intensively studied in higher plants. The cpSRP system derived from the prokaryotic SRP pathway, which mediates the cotranslational protein transport to the bacterial plasma membrane. Chloroplasts contain homologs of several components of the bacterial SRP system. The function of these conserved components in post- and/or cotranslational protein transport and chloroplast-specific modifications of these transport mechanisms are described. Furthermore, recent studies of cpSRP systems in algae and lower plants are summarized and their impact on understanding the evolution of the cpSRP system are discussed.

  10. Tagetitoxin inhibits chloroplast RNA synthesis

    SciTech Connect

    Mathews, D.E.; Durbin, R.D.

    1987-04-01

    Tagetitoxin is a non-host specific phytotoxin which inhibits chloroplast development. Chloroplast encoded gene products as well as their transcripts are conspicuously depleted in toxin-treated tissue. Intact chloroplasts from 8-9 day old peas were incubated for 60 min. in the presence of tagetitoxin. This treatment reduced RNA synthesis but did not affect protein synthesis as measured by the incorporation of radiolabeled uridine or methionine, respectively. Tagetitoxin also inhibited chloroplast RNA synthesis in vitro. Total UTP incorporation was reduced 50% by 0.5..mu..M tagetitoxin in transcriptionally active chloroplast extracts containing 5mg/ml protein. In vitro transcription with purified E. coli RNA polymerase was also inhibited by tagetitoxin, yet wheat germ RNA polymerase II and several bacteriophage RNA polymerase enzymes were unaffected. Recent evidence suggests that RNA polymerase from chloroplasts and prokaryotes may share extensive homology. In light of this evidence and the authors own data, they propose that tagetitoxin directly inhibits chloroplast RNA polymerase.

  11. Genetic Analysis of Chloroplast Translation

    SciTech Connect

    Barkan, Alice

    2005-08-15

    The assembly of the photosynthetic apparatus requires the concerted action of hundreds of genes distributed between the two physically separate genomes in the nucleus and chloroplast. Nuclear genes coordinate this process by controlling the expression of chloroplast genes in response to developmental and environmental cues. However, few regulatory factors have been identified. We used mutant phenotypes to identify nuclear genes in maize that modulate chloroplast translation, a key control point in chloroplast gene expression. This project focused on the nuclear gene crp1, required for the translation of two chloroplast mRNAs. CRP1 is related to fungal proteins involved in the translation of mitochondrial mRNAs, and is the founding member of a large gene family in plants, with {approx}450 members. Members of the CRP1 family are defined by a repeated 35 amino acid motif called a ''PPR'' motif. The PPR motif is closely related to the TPR motif, which mediates protein-protein interactions. We and others have speculated that PPR tracts adopt a structure similar to that of TPR tracts, but with a substrate binding surface adapted to bind RNA instead of protein. To understand how CRP1 influences the translation of specific chloroplast mRNAs, we sought proteins that interact with CRP1, and identified the RNAs associated with CRP1 in vivo. We showed that CRP1 is associated in vivo with the mRNAs whose translation it activates. To explore the functions of PPR proteins more generally, we sought mutations in other PPR-encoding genes: mutations in the maize PPR2 and PPR4 were shown to disrupt chloroplast ribosome biogenesis and chloroplast trans-splicing, respectively. These and other results suggest that the nuclear-encoded PPR family plays a major role in modulating the expression of the chloroplast genome in higher plants.

  12. Heme content in developing chloroplasts

    SciTech Connect

    Thomas, J.; Weinstein, J.D. )

    1991-05-01

    Heme regulates tetrapyrrole biosynthesis by inhibition of {delta}-aminolevulinic acid synthesis, product inhibition of heme synthesis, and possibly other mechanisms. Determination of the physiological relevance of this inhibition requires a sensitive measurement which can distinguish regulatory free heme from heme which is an integral part of functional hemoproteins. A preliminary estimate was provided by reconstituting peroxidase activity from apo-peroxidase and the heme contained in broken plastids. However, subsequent experiments have suggested that this initial estimate was too large due to reconstitution of apo-peroxidase with heme from functional hemoproteins (i.e. heme stealing). The authors have now refined the measurement techniques to greatly reduce the extent of this heme stealing. Incubation of broken plastids with apo-peroxidase at 10C resolves the kinetics of reconstitution into two components. A fast component levels off after 100 min, and a slow component increases linearly for up to 6 hours. They believe that the heme which reconstitutes during the fast phase represents free heme, and the linear slow component represents heme stealing. In support of this theory, incubation at 15C increases the rate of both components. However, extrapolation to zero time of the slow components of the 10C and 15C time courses results in equivalent amounts of heme. Based on this kinetic differentiation between free heme and hemoprotein heme, chloroplasts isolated from cucumber cotyledons after 30 h of greening contain substantially greater amounts of free heme than etioplasts.

  13. Transcriptomic and proteomic approach to identify differentially expressed genes and proteins in Arabidopsis thaliana mutants lacking chloroplastic 1 and cytosolic FBPases reveals several levels of metabolic regulation.

    PubMed

    Soto-Suárez, Mauricio; Serrato, Antonio J; Rojas-González, José A; Bautista, Rocío; Sahrawy, Mariam

    2016-12-01

    During the photosynthesis, two isoforms of the fructose-1,6-bisphosphatase (FBPase), the chloroplastidial (cFBP1) and the cytosolic (cyFBP), catalyse the first irreversible step during the conversion of triose phosphates (TP) to starch or sucrose, respectively. Deficiency in cyFBP and cFBP1 isoforms provokes an imbalance of the starch/sucrose ratio, causing a dramatic effect on plant development when the plastidial enzyme is lacking. We study the correlation between the transcriptome and proteome profile in rosettes and roots when cFBP1 or cyFBP genes are disrupted in Arabidopsis thaliana knock-out mutants. By using a 70-mer oligonucleotide microarray representing the genome of Arabidopsis we were able to identify 1067 and 1243 genes whose expressions are altered in the rosettes and roots of the cfbp1 mutant respectively; whilst in rosettes and roots of cyfbp mutant 1068 and 1079 genes are being up- or down-regulated respectively. Quantitative real-time PCR validated 100% of a set of 14 selected genes differentially expressed according to our microarray analysis. Two-dimensional (2-D) gel electrophoresis-based proteomic analysis revealed quantitative differences in 36 and 26 proteins regulated in rosettes and roots of cfbp1, respectively, whereas the 18 and 48 others were regulated in rosettes and roots of cyfbp mutant, respectively. The genes differentially expressed and the proteins more or less abundant revealed changes in protein metabolism, RNA regulation, cell signalling and organization, carbon metabolism, redox regulation, and transport together with biotic and abiotic stress. Notably, a significant set (25%) of the proteins identified were also found to be regulated at a transcriptional level. This transcriptomic and proteomic analysis is the first comprehensive and comparative study of the gene/protein re-adjustment that occurs in photosynthetic and non-photosynthetic organs of Arabidopsis mutants lacking FBPase isoforms.

  14. Studying Arabidopsis chloroplast structural organisation using transmission electron microscopy.

    PubMed

    Hyman, Stefan; Jarvis, R Paul

    2011-01-01

    Chloroplasts, as well as other, non-photosynthetic types of plastid, are characteristic structures within plant cells. They are relatively large organelles (typically 1-5 μm in diameter), and so can readily be analysed by electron microscopy. Chloroplast structure is remarkably complex, comprising at least six distinct sub-organellar compartments, and is sensitive to developmental changes, environmental effects, and genetic lesions. Transmission electron microscopy (TEM), therefore, represents a powerful technique for monitoring the effects of various changing parameters or treatments on the development and differentiation of these important organelles. We describe a method for the analysis of Arabidopsis plant material by TEM, primarily for the assessment of plastid ultrastructure.

  15. Chloroplast signaling: retrograde regulation revelations.

    PubMed

    Beale, Samuel I

    2011-05-24

    Developing chloroplasts are able to communicate their status to the nucleus and regulate expression of genes whose products are needed for photosynthesis. Heme is revealed to be a signaling molecule for this retrograde communication.

  16. Transients in chloroplast gene transcription

    SciTech Connect

    Puthiyaveetil, Sujith; Allen, John F.

    2008-04-18

    Transcriptional regulation of chloroplast genes is demonstrated by Quantitative Polymerase Chain Reaction (qPCR). These genes encode apoproteins of the reaction centres of photosystem I and photosystem II. Their transcription is regulated by changes in wavelength of light selectively absorbed by photosystem I and photosystem II, and therefore by the redox state of an electron carrier located between the two photosystems. Chloroplast transcriptional redox regulation is shown to have greater amplitude, and the kinetics of transcriptional changes are more complex, than suggested by previous experiments using only DNA probes in Northern blot experiments. Redox effects on chloroplast transcription appear to be superimposed on an endogenous rhythm of mRNA abundance. The functional significance of these transients in chloroplast gene transcription is discussed.

  17. Chloroplasts Isolation from Chlamydomonas reinhardtii under Nitrogen Stress

    PubMed Central

    Yang, Miao; Jiang, Jun-Peng; Xie, Xi; Chu, Ya-Dong; Fan, Yan; Cao, Xu-Peng; Xue, Song; Chi, Zhan-You

    2017-01-01

    Triacylglycerols are produced in abundance through chloroplast and endoplasmic reticulum pathways in some microalgae exposed to stress, though the relative contribution of either pathway remains elusive. Characterization of these pathways requires isolation of the organelles. In this study, an efficient and reproducible approach, including homogenous batch cultures of nitrogen-deprived algal cells in photobioreactors, gentle cell disruption using a simple custom-made disruptor with mechanical shear force, optimized differential centrifugation and Percoll density gradient centrifugation, was developed to isolate chloroplasts from Chlamydomonas reinhardtii subjected to nitrogen stress. Using this approach, the maximum limited stress duration was 4 h and the stressed cells exhibited 19 and 32% decreases in intracellular chlorophyll and nitrogen content, respectively. Chloroplasts with 48 – 300 μg chlorophyll were successfully isolated from stressed cells containing 10 mg chlorophyll. These stressed chloroplasts appeared intact, as monitored by ultrastructure observation and a novel quality control method involving the fatty acid biomarkers. This approach can provide sufficient quantities of intact stressed chloroplasts for subcellular biochemical studies in microalgae. PMID:28900438

  18. Update on chloroplast research: new tools, new topics, and new trends.

    PubMed

    Armbruster, Ute; Pesaresi, Paolo; Pribil, Mathias; Hertle, Alexander; Leister, Dario

    2011-01-01

    Chloroplasts, the green differentiation form of plastids, are the sites of photosynthesis and other important plant functions. Genetic and genomic technologies have greatly boosted the rate of discovery and functional characterization of chloroplast proteins during the past decade. Indeed, data obtained using high-throughput methodologies, in particular proteomics and transcriptomics, are now routinely used to assign functions to chloroplast proteins. Our knowledge of many chloroplast processes, notably photosynthesis and photorespiration, has reached such an advanced state that biotechnological approaches to crop improvement now seem feasible. Meanwhile, efforts to identify the entire complement of chloroplast proteins and their interactions are progressing rapidly, making the organelle a prime target for systems biology research in plants.

  19. The Effect of Gametogenesis Regimes on the Chloroplast Genetic System of CHLAMYDOMONAS REINHARDTII

    PubMed Central

    Sears, Barbara B.; Boynton, John E.; Gillham, Nicholas W.

    1980-01-01

    In Chlamydomonas reinhardtii, gamete differentiation is induced by nitrogen deprivation. While cellular nitrogen content and amount of chloroplast DNA in cells of both mating types are reduced during gametogenesis, the spontaneous transmission of paternal (mt-) chloroplast alleles in crosses is specifically affected by the stringency of the nitrogen starvation regime used for pregrowth and gametogenesis of the mt- parent. In all cases, reciprocal crosses yielded biparental zygospores whose clones contain predominantly cells expressing only the chloroplast alleles from the maternal (mt+) parent. No differences attributable to strain divergence were seen in chloroplast gene inheritance pattern, DNA content, or the relative frequency of transmission of paternal chloroplast alleles to progeny of biparental zygospores. PMID:17249065

  20. Intercalation of psoralen into DNA of plastid chromosomes decreases late during barley chloroplast development.

    PubMed Central

    Davies, J P; Thompson, R J; Mosig, G

    1991-01-01

    We have used a DNA crosslinking assay to measure intercalation of the psoralen derivative HMT (4'-hydroxymethyl-4,5',8-trimethylpsoralen) into barley (Hordeum vulgare) plastid chromosomal DNA during chloroplast and etioplast development. Intercalation into DNA in intact plastids in vivo and in plastid lysates in vitro shows that chromosomal DNA in the most mature chloroplasts intercalates HMT less efficiently than DNA in younger chloroplasts. In contrast, there is no change in HMT intercalation during etioplast differentiation in the dark. Our results also show that DNA in higher plant plastid chromosomes is under superhelical tension in vivo. The lower susceptibility to HMT intercalation of DNA in the most mature chloroplasts indicates that late during chloroplast development the superhelical tension or the binding of proteins to the DNA or both change. Images PMID:1923805

  1. Mutation of the rice ASL2 gene encoding plastid ribosomal protein L21 causes chloroplast developmental defects and seedling death.

    PubMed

    Lin, D; Jiang, Q; Zheng, K; Chen, S; Zhou, H; Gong, X; Xu, J; Teng, S; Dong, Y

    2015-05-01

    The plastid ribosome proteins (PRPs) play important roles in plastid protein biosynthesis, chloroplast differentiation and early chloroplast development. However, the specialised functions of individual protein components of the chloroplast ribosome in rice (Oryza sativa) remain unresolved. In this paper, we identified a novel rice PRP mutant named asl2 (Albino seedling lethality 2) exhibiting an albino, seedling death phenotype. In asl2 mutants, the alteration of leaf colour was associated with chlorophyll (Chl) content and abnormal chloroplast development. Through map-based cloning and complementation, the mutated ASL2 gene was isolated and found to encode the chloroplast 50S ribosome protein L21 (RPL21c), a component of the chloroplast ribosome large subunit, which was localised in chloroplasts. ASL2 was expressed at a higher level in the plumule and leaves, implying its tissue-specific expression. Additionally, the expression of ASL2 was regulated by light. The transcript levels of the majority of genes for Chl biosynthesis, photosynthesis and chloroplast development were strongly affected in asl2 mutants. Collectively, the absence of functional ASL2 caused chloroplast developmental defects and seedling death. This report establishes the important role of RPL21c in chloroplast development in rice. © 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.

  2. Chloroplasts of salt-grown Arabidopsis seedlings are impaired in structure, genome copy number and transcript levels.

    PubMed

    Peharec Štefanić, Petra; Koffler, Tal; Adler, Guy; Bar-Zvi, Dudy

    2013-01-01

    The chloroplast is the most prominent and metabolically active plastid in photosynthetic plants. Chloroplasts differentiate from proplastids in the plant meristem. Plant plastids contain multiple copies of a small circular genome. The numbers of chloroplasts per mesophyll cell and of plastid genome copies are affected by developmental stage and environmental signals. We compared chloroplast structure, gene expression and genome copy number in Arabidopsis seedlings germinated and grown under optimal conditions to those in seedlings germinated and grown in the presence of NaCl. Chloroplasts of the NaCl-grown seedlings were impaired, with less developed thylakoid and granum membranes than control seedlings. In addition, chloroplasts of salt-grown Arabidopsis seedlings accumulated more starch grains than those in the respective control plants. Steady-state transcript levels of chloroplast-encoded genes and of nuclear genes encoding chloroplast proteins were reduced in salt-grown seedlings. This reduction did not result from a global decrease in gene expression, since the expression of other nuclear genes was induced or not affected. Average cellular chloroplast genome copy number was reduced in salt-grown seedlings, suggesting that the reduction in steady-state transcript levels of chloroplast-encoded genes might result from a decrease in template DNA.

  3. Chloroplast in Plant-Virus Interaction

    PubMed Central

    Zhao, Jinping; Zhang, Xian; Hong, Yiguo; Liu, Yule

    2016-01-01

    In plants, the chloroplast is the organelle that conducts photosynthesis. It has been known that chloroplast is involved in virus infection of plants for approximate 70 years. Recently, the subject of chloroplast-virus interplay is getting more and more attention. In this article we discuss the different aspects of chloroplast-virus interaction into three sections: the effect of virus infection on the structure and function of chloroplast, the role of chloroplast in virus infection cycle, and the function of chloroplast in host defense against viruses. In particular, we focus on the characterization of chloroplast protein-viral protein interactions that underlie the interplay between chloroplast and virus. It can be summarized that chloroplast is a common target of plant viruses for viral pathogenesis or propagation; and conversely, chloroplast and its components also can play active roles in plant defense against viruses. Chloroplast photosynthesis-related genes/proteins (CPRGs/CPRPs) are suggested to play a central role during the complex chloroplast-virus interaction. PMID:27757106

  4. Transglutaminases and their substrates in kinetin-stimulated etioplast-to-chloroplast transformation in cucumber cotyledons.

    PubMed

    Sobieszczuk-Nowicka, Ewa; Krzesłowska, Magdalena; Legocka, Jolanta

    2008-11-01

    In the light of our previous work, we know that there is a relationship between bound polyamines and the chloroplast differentiation process. This relationship may represent an important component of the process and be part of the mechanism of kinetin action, which stimulates chloroplast differentiation. To clarify the nature of the binding of polyamines to chloroplast structures, the possible involvement of transglutaminases in kinetin-stimulated chloroplast photodevelopment was investigated. Immunodetection of transglutaminases revealed bands at 77, 50 and 30 kDa both in etioplasts and chloroplasts. The data indicated a positive correlation between enzyme level and activity. It also demonstrated the regulation of transglutaminase protein expression by kinetin. The suborganellar location of transglutaminases by electron microscopy showed that the enzyme is peculiarly localised, mainly in pro-thylakoids and appressed grana thylakoids. The data corroborated that spermidine post-translational modification of certain plastid proteins of 58, 29, 26 and 12 kDa occurred. The results we obtained suggest that transglutaminases take part in the formation of the chloroplast structure via a mechanism whereby polyamines bind to their protein substrates. These findings about the effect of kinetin on conjugation provide a new contribution to the understanding of the mechanism of kinetin action on etioplast-to chloroplast transformation.

  5. AKR2A-mediated import of chloroplast outer membrane proteins is essential for chloroplast biogenesis.

    PubMed

    Bae, Wonsil; Lee, Yong Jik; Kim, Dae Heon; Lee, Junho; Kim, Soojin; Sohn, Eun Ju; Hwang, Inhwan

    2008-02-01

    In plant cells, chloroplasts have essential roles in many biochemical reactions and physiological responses. Chloroplasts require numerous protein components, but only a fraction of these proteins are encoded by the chloroplast genome. Instead, most are encoded by the nuclear genome and imported into chloroplasts from the cytoplasm post-translationally. Membrane proteins located in the chloroplast outer envelope membrane (OEM) have a critical function in the import of proteins into the chloroplast. However, the biogenesis of chloroplast OEM proteins remains poorly understood. Here, we report that an Arabidopsis ankyrin repeat protein, AKR2A, plays an essential role in the biogenesis of the chloroplast OEM proteins. AKR2A binds to chloroplast OEM protein targeting signals, as well as to chloroplasts. It also displays chaperone activity towards chloroplast OEM proteins, and facilitates the targeting of OEP7 to chloroplasts in vitro. AKR2A RNAi in plants with an akr2b knockout background showed greatly reduced levels of chloroplast proteins, including OEM proteins, and chloroplast biogenesis was also defective. Thus, AKR2A functions as a cytosolic mediator for sorting and targeting of nascent chloroplast OEM proteins to the chloroplast.

  6. Evolution of Chloroplast J Proteins

    PubMed Central

    Chiu, Chi-Chou; Chen, Lih-Jen; Su, Pai-Hsiang; Li, Hsou-min

    2013-01-01

    Hsp70 chaperones are involved in multiple biological processes and are recruited to specific processes by designated J domain-containing cochaperones, or J proteins. To understand the evolution and functions of chloroplast Hsp70s and J proteins, we identified the Arabidopsis chloroplast J protein constituency using a combination of genomic and proteomic database searches and individual protein import assays. We show that Arabidopsis chloroplasts have at least 19 J proteins, the highest number of confirmed J proteins for any organelle. These 19 J proteins are classified into 11 clades, for which cyanobacteria and glaucophytes only have homologs for one clade, green algae have an additional three clades, and all the other 7 clades are specific to land plants. Each clade also possesses a clade-specific novel motif that is likely used to interact with different client proteins. Gene expression analyses indicate that most land plant-specific J proteins show highly variable expression in different tissues and are down regulated by low temperatures. These results show that duplication of chloroplast Hsp70 in land plants is accompanied by more than doubling of the number of its J protein cochaperones through adding new J proteins with novel motifs, not through duplications within existing families. These new J proteins likely recruit chloroplast Hsp70 to perform tissue specific functions related to biosynthesis rather than to stress resistance. PMID:23894646

  7. Chloroplast evolution: secondary symbiogenesis and multiple losses.

    PubMed

    Cavalier-Smith, T

    2002-01-22

    Chloroplasts originated from cyanobacteria only once, but have been laterally transferred to other lineages by symbiogenetic cell mergers. Such secondary symbiogenesis is rarer and chloroplast losses commoner than often assumed.

  8. Spontaneous capture of oilseed rape (Brassica napus) chloroplasts by wild B. rapa: implications for the use of chloroplast transformation for biocontainment.

    PubMed

    Haider, Nadia; Allainguillaume, Joel; Wilkinson, Mike J

    2009-04-01

    Environmental concerns over the cultivation of Genetically Modified (GM) crops largely centre on the ecological consequences following gene flow to wild relatives. One attractive solution is to deploy biocontainment measures that prevent hybridization. Chloroplast transformation is the most advanced biocontainment method but is compromised by chloroplast capture (hybridization through the maternal lineage). To date, however, there is a paucity of information on the frequency of chloroplast capture in the wild. Oilseed rape (Brassica napus, AACC) frequently hybridises with wild Brassica rapa (AA, as paternal parent) and yields B. rapa-like introgressed individuals after only two generations. In this study we used chloroplast CAPS markers that differentiate between the two species to survey wild and weedy populations of B. rapa for the capture of B. napus chloroplasts. A total of 464 B. rapa plants belonging to 14 populations growing either in close proximity to B. napus (i.e. sympatric <5 m) or else were allopatric from the crop (>1 km) were assessed for chloroplast capture using PCR (trnL-F) and CAPS (trnT-L-Xba I) markers. The screen revealed that two sympatric B. rapa populations included 53 plants that possessed the chloroplast of B. napus. In order to discount these B. rapa plants as F(1) crop-wild hybrids, we used a C-genome-specific marker and found that 45 out of 53 plants lacked the C-genome and so were at least second generation introgressants. The most plausible explanation is that these individuals represent multiple cases of chloroplast capture following introgressive hybridisation through the female germ line from the crop. The abundance of such plants in sympatric sites thereby questions whether the use of chloroplast transformation would provide a sufficient biocontainment for GM oilseed rape in the United Kingdom.

  9. Confocal laser scanning microscopy detection of chlorophylls and carotenoids in chloroplasts and chromoplasts of tomato fruit.

    PubMed

    D'Andrea, Lucio; Amenós, Montse; Rodríguez-Concepción, Manuel

    2014-01-01

    Plant cells are unique among eukaryotic cells because of the presence of plastids, including chloroplasts and chromoplasts. Chloroplasts are found in green tissues and harbor the photosynthetic machinery (including chlorophyll molecules), while chromoplasts are present in non-photosynthetic tissues and accumulate large amounts of carotenoids. During tomato fruit development, chloroplasts are converted into chromoplasts that accumulate high levels of lycopene, a linear carotenoid responsible for the characteristic red color of ripe fruit. Here, we describe a simple and fast method to detect both types of fully differentiated plastids (chloroplasts and chromoplasts), as well as intermediate stages, in fresh tomato fruits. The method is based on the differential autofluorescence of chlorophylls and carotenoids (lycopene) detected by Confocal Laser Scanning Microscopy.

  10. Isolation of chloroplastic phosphoglycerate kinase

    SciTech Connect

    Macioszek, J.; Anderson, L.E. ); Anderson, J.B. )

    1990-09-01

    We report here a method for the isolation of high specific activity phosphoglycerate kinase (EC 2.7.2.3) from chloroplasts. The enzyme has been purified over 200-fold from pea (Pisum sativum L.) stromal extracts to apparent homogeneity with 23% recovery. Negative cooperativity is observed with the two enzyme phosphoglycerate kinase/glyceraldehyde-3-P dehydrogenase (EC 1.2.1.13) couple restored from the purified enzymes when NADPH is the reducing pyridine nucleotide, consistent with earlier results obtained with crude chloroplastic extracts. Michaelis Menten kinetics are observed when 3-phosphoglycerate is held constant and phosphoglycerate kinase is varied, which suggests that phosphoglycerate kinase-bound 1,3-bisphosphoglycerate may be the preferred substrate for glyceraldehyde-3-P dehydrogenase in the chloroplast.

  11. Chloroplast retrograde signal regulates flowering

    PubMed Central

    Feng, Peiqiang; Guo, Hailong; Chi, Wei; Chai, Xin; Sun, Xuwu; Xu, Xiumei; Ma, Jinfang; Rochaix, Jean-David; Leister, Dario; Wang, Haiyang; Lu, Congming; Zhang, Lixin

    2016-01-01

    Light is a major environmental factor regulating flowering time, thus ensuring reproductive success of higher plants. In contrast to our detailed understanding of light quality and photoperiod mechanisms involved, the molecular basis underlying high light-promoted flowering remains elusive. Here we show that, in Arabidopsis, a chloroplast-derived signal is critical for high light-regulated flowering mediated by the FLOWERING LOCUS C (FLC). We also demonstrate that PTM, a PHD transcription factor involved in chloroplast retrograde signaling, perceives such a signal and mediates transcriptional repression of FLC through recruitment of FVE, a component of the histone deacetylase complex. Thus, our data suggest that chloroplasts function as essential sensors of high light to regulate flowering and adaptive responses by triggering nuclear transcriptional changes at the chromatin level. PMID:27601637

  12. CHLOROPLAST DEVELOPMENT IN OCHROMONAS DANICA

    PubMed Central

    Gibbs, Sarah P.

    1962-01-01

    When dark-grown cells of Ochromonas danica are placed in the light, the amount of chlorophyll a per cell increases 82-fold; the content of carotenoid pigment, 24-fold. Concomitantly with this increase in chlorophyll and carotenoid pigment, the small proplastid of dark-grown cells develops into a large lamellate chloroplast. During the first 12 hours in the light, vesicles appear within the loose clusters of dense chloroplast granules, enlarge, align themselves into rows (plates in three dimensions), and fuse into discs. Double discs may form from the more or less simultaneous fusion of two adjacent plates of vesicles or by the addition of vesicles to an already formed single disc. Three-disc bands arise by the addition of a disc to an already formed two-disc band through the approach and fusion of more vesicles. After 24 hours in the light, most of the chloroplast bands contain three discs, but the chloroplasts are still small. After 48 hours in the light, almost all the cells contain full-sized chloroplasts with a full complement of three-disc bands. However, at this time the amount of chlorophyll a and carotenoid pigment is only one-half of maximum. During the next 3 days in the light, as the number of chlorophyll and carotenoid molecules per chloroplast approximately doubles, there is a compression of the discs in each band (from 180 to 130 A) and a precise alignment of their membranes. Changes also occur in the nucleus when dark-grown cells are placed in the light. There is an increase in the number of small nucleolar bodies, many of which lie directly against the nuclear envelope, and in a few cells a dense mass of granules is seen between the two membranes of the nuclear envelope. PMID:13947686

  13. Protein import into chloroplasts requires a chloroplast ATPase

    SciTech Connect

    Pain, D.; Blobel, G.

    1987-05-01

    The authors have transcribed mRNA from a cDNA clone coding for pea ribulose-1,5-bisphosphate carboxylase, translated the mRNA in a wheat germ cell-free system, and studied the energy requirement for posttranslational import of the (/sup 35/S)methionine-labeled protein into the stroma of pea chloroplasts. They found that import depends on ATP hydrolysis within the stroma. Import is not inhibited when H/sup +/, K/sup +/, Na/sup +/, or divalent cation gradients across the chloroplast membranes are dissipated by ionophores, as long as exogenously added ATP is also present during the import reaction. The data suggest that protein import into the chloroplast stroma requires a chloroplast ATPase that does not function to generate a membrane potential for driving the import reaction but that exerts its effect in another, yet-to-be-determined, mode. They have carried out a preliminary characterization of this ATPase regarding its nucleotide specificity and the effects of various ATPase inhibitors.

  14. Analysis of the differential response of five annuals to elevated CO sub 2 during growth

    SciTech Connect

    Garbutt, K. ); Williams, W.E. ); Bazzaz, F.A. )

    1990-06-01

    In order to investigate the effects, without competition, of CO{sub 2} on germination, growth, physiological response, and reproduction, the authors focussed on co-occurring species that are prominent members of an annual community in Illinois. Five species of old field annual plants - Abutilon theophrasti (C{sub 3}), Amaranthus retroflexus (C{sub 4}), Ambrosia artemisiifolia (C{sub 3}), Chenopodium album (C{sub 3}), and Setaria faberii (C{sub 4}) - were grown for their entire life cycle as individuals at CO{sub 2} concentration of 350 {mu}L/O, 500 {mu}L/L, and 700 {mu}L/L. Emergence time, growth rate, shoot water status, photosynthesis, conductance, flowering time, nitrogen content, and biomass and reproductive biomass were measured. There was no detectable effect of enhanced CO{sub 2} on timing of emergency in any of the species. The three levels of carbon dioxide concentration were shown to produce varying effects on remaining quantities measured in the five different plants. Some of these differences were not statistically significant. The response of most characters had a significant species {times} CO{sub 2} interaction. However, this was not simply caused by the C{sub 3}/C{sub 4} dichotomy. Reproductive biomass (seed, fruits, and flowers) increased with increasing CO{sub 2} in Amaranthus (C{sub 4}) and in Chenopodium and Ambrosia (both C{sub 3}), but there was no change in Setaria (C{sub 4}), and Abutilon (C{sub 3}) showed a peak at 500 {mu}L/L. Species of the same community differed in their response to CO{sub 2}, and these differences may help explain the outcome of competitive interactions among these species above ambient CO{sub 2} levels.

  15. Mutational Dynamics of Aroid Chloroplast Genomes

    PubMed Central

    Ahmed, Ibrar; Biggs, Patrick J.; Matthews, Peter J.; Collins, Lesley J.; Hendy, Michael D.; Lockhart, Peter J.

    2012-01-01

    A characteristic feature of eukaryote and prokaryote genomes is the co-occurrence of nucleotide substitution and insertion/deletion (indel) mutations. Although similar observations have also been made for chloroplast DNA, genome-wide associations have not been reported. We determined the chloroplast genome sequences for two morphotypes of taro (Colocasia esculenta; family Araceae) and compared these with four publicly available aroid chloroplast genomes. Here, we report the extent of genome-wide association between direct and inverted repeats, indels, and substitutions in these aroid chloroplast genomes. We suggest that alternative but not mutually exclusive hypotheses explain the mutational dynamics of chloroplast genome evolution. PMID:23204304

  16. Chloroplast division in higher plants requires members of two functionally divergent gene families with homology to bacterial ftsZ.

    PubMed Central

    Osteryoung, K W; Stokes, K D; Rutherford, S M; Percival, A L; Lee, W Y

    1998-01-01

    The division of plastids is critical for viability in photosynthetic eukaryotes, but the mechanisms associated with this process are still poorly understood. We previously identified a nuclear gene from Arabidopsis encoding a chloroplast-localized homolog of the bacterial cell division protein FtsZ, an essential cytoskeletal component of the prokaryotic cell division apparatus. Here, we report the identification of a second nuclear-encoded FtsZ-type protein from Arabidopsis that does not contain a chloroplast targeting sequence or other obvious sorting signals and is not imported into isolated chloroplasts, which strongly suggests that it is localized in the cytosol. We further demonstrate using antisense technology that inhibiting expression of either Arabidopsis FtsZ gene (AtFtsZ1-1 or AtFtsZ2-1) in transgenic plants reduces the number of chloroplasts in mature leaf cells from 100 to one, indicating that both genes are essential for division of higher plant chloroplasts but that each plays a distinct role in the process. Analysis of currently available plant FtsZ sequences further suggests that two functionally divergent FtsZ gene families encoding differentially localized products participate in chloroplast division. Our results provide evidence that both chloroplastic and cytosolic forms of FtsZ are involved in chloroplast division in higher plants and imply that important differences exist between chloroplasts and prokaryotes with regard to the roles played by FtsZ proteins in the division process. PMID:9836740

  17. Cytosolic events involved in chloroplast protein targeting.

    PubMed

    Lee, Dong Wook; Jung, Chanjin; Hwang, Inhwan

    2013-02-01

    Chloroplasts are unique organelles that are responsible for photosynthesis. Although chloroplasts contain their own genome, the majority of chloroplast proteins are encoded by the nuclear genome. These proteins are transported to the chloroplasts after translation in the cytosol. Chloroplasts contain three membrane systems (outer/inner envelope and thylakoid membranes) that subdivide the interior into three soluble compartments known as the intermembrane space, stroma, and thylakoid lumen. Several targeting mechanisms are required to deliver proteins to the correct chloroplast membrane or soluble compartment. These mechanisms have been extensively studied using purified chloroplasts in vitro. Prior to targeting these proteins to the various compartments of the chloroplast, they must be correctly sorted in the cytosol. To date, it is not clear how these proteins are sorted in the cytosol and then targeted to the chloroplasts. Recently, the cytosolic carrier protein AKR2 and its associated cofactor Hsp17.8 for outer envelope membrane proteins of chloroplasts were identified. Additionally, a mechanism for controlling unimported plastid precursors in the cytosol has been discovered. This review will mainly focus on recent findings concerning the possible cytosolic events that occur prior to protein targeting to the chloroplasts. This article is part of a Special Issue entitled: Protein Import and Quality Control in Mitochondria and Plastids. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. Targeting of nucleus-encoded proteins to chloroplasts in plants.

    PubMed

    Jarvis, Paul

    2008-07-01

    Most chloroplast proteins are encoded in the nucleus and synthesized on free, cytosolic ribosomes in precursor form. Each precursor has an amino-terminal extension called a transit peptide, which directs the protein through a post-translational targeting pathway and is removed upon arrival inside the organelle. This 'protein import' process is mediated by the coordinate action of two multiprotein complexes, one in each of the envelope membranes: the TOC and TIC (Translocon at the Outer/ Inner envelope membrane of Chloroplasts) machines. Many components of these complexes have been identified biochemically in pea; these include transit peptide receptors, channel proteins, and molecular chaperones. Intriguingly, the Arabidopsis genome encodes multiple, homologous genes for receptor components of the TOC complex. Careful analysis indicated that the different receptor isoforms operate in different import pathways with distinct precursor recognition specificities. These 'substrate-specific' import pathways might play a role in the differentiation of different plastid types, and/or act to prevent deleterious competition effects between abundant and nonabundant precursors. Until recently, all proteins destined for internal chloroplast compartments were thought to possess a cleavable transit peptide, and to engage the TOC/TIC machinery. New studies using proteomics and other approaches have revealed that this is far from true. Remarkably, a significant number of chloroplast proteins are transported via a pathway that involves the endoplasmic reticulum and Golgi apparatus. Other recent reports have elucidated an intriguing array of protein targeting routes leading to the envelope membranes themselves.

  19. Ribonucleic acid synthesis in chloroplasts

    PubMed Central

    Hartley, M. R.; Ellis, R. J.

    1973-01-01

    Chloroplasts isolated from young spinach leaves incorporate [3H]uridine into RNA. This incorporation shows an absolute requirement for light and does not occur in lysed chloroplasts. Fractionation by polyacrylamide-gel electrophoresis of the RNA synthesized in vitro reveals a major discrete product of molecular weight 2.7×106 and two minor products of molecular weight 1.2×106 and 0.47×106. These discrete products are super-imposed on a background of polydisperse RNA. The incorporation of 32Pi into chloroplast rRNA species (mol.wt. 1.05×106 and 0.56×106) in excised spinach leaves proceeds after a distinct lag period compared with the incorporation into cytoplasmic rRNA species (mol.wt. 1.34×106 and 0.7×106). Incorporation of 32Pi into chloroplast RNA species of molecular weight 2.7×106, 1.2×106, 0.65×106 and 0.47×106 proceeds without such a time-lag. The kinetics of labelling of the individual RNA components is consistent with the rapidly labelled RNA species of molecular weight 1.2×106 and 0.65×106 being precursors to the more slowly labelled rRNA species of molecular weight 1.05×106 and 0.56×106 respectively. PMID:4723226

  20. Comparative chromatography of chloroplast pigment

    NASA Technical Reports Server (NTRS)

    Grandolfo, M.; Sherma, J.; Strain, H. H.

    1969-01-01

    Methods for isolation of low concentration pigments of the cocklebur species are described. The methods entail two step chromatography so that the different sorption properties of the various pigments in varying column parameters can be utilized. Columnar and thin layer methods are compared. Many conditions influence separability of the chloroplasts.

  1. Two distinct redox cascades cooperatively regulate chloroplast functions and sustain plant viability

    PubMed Central

    Yoshida, Keisuke; Hisabori, Toru

    2016-01-01

    The thiol-based redox regulation system is believed to adjust chloroplast functions in response to changes in light environments. A redox cascade via the ferredoxin-thioredoxin reductase (FTR)/thioredoxin (Trx) pathway has been traditionally considered to serve as a transmitter of light signals to target enzymes. However, emerging data indicate that chloroplasts have a complex redox network composed of diverse redox-mediator proteins and target enzymes. Despite extensive research addressing this system, two fundamental questions are still unresolved: How are redox pathways orchestrated within chloroplasts, and why are chloroplasts endowed with a complicated redox network? In this report, we show that NADPH-Trx reductase C (NTRC) is a key redox-mediator protein responsible for regulatory functions distinct from those of the classically known FTR/Trx system. Target screening and subsequent biochemical assays indicated that NTRC and the Trx family differentially recognize their target proteins. In addition, we found that NTRC is an electron donor to Trx-z, which is a key regulator of gene expression in chloroplasts. We further demonstrate that cooperative control of chloroplast functions via the FTR/Trx and NTRC pathways is essential for plant viability. Arabidopsis double mutants impaired in FTR and NTRC expression displayed lethal phenotypes under autotrophic growth conditions. This severe growth phenotype was related to a drastic loss of photosynthetic performance. These combined results provide an expanded map of the chloroplast redox network and its biological functions. PMID:27335455

  2. Two distinct redox cascades cooperatively regulate chloroplast functions and sustain plant viability.

    PubMed

    Yoshida, Keisuke; Hisabori, Toru

    2016-07-05

    The thiol-based redox regulation system is believed to adjust chloroplast functions in response to changes in light environments. A redox cascade via the ferredoxin-thioredoxin reductase (FTR)/thioredoxin (Trx) pathway has been traditionally considered to serve as a transmitter of light signals to target enzymes. However, emerging data indicate that chloroplasts have a complex redox network composed of diverse redox-mediator proteins and target enzymes. Despite extensive research addressing this system, two fundamental questions are still unresolved: How are redox pathways orchestrated within chloroplasts, and why are chloroplasts endowed with a complicated redox network? In this report, we show that NADPH-Trx reductase C (NTRC) is a key redox-mediator protein responsible for regulatory functions distinct from those of the classically known FTR/Trx system. Target screening and subsequent biochemical assays indicated that NTRC and the Trx family differentially recognize their target proteins. In addition, we found that NTRC is an electron donor to Trx-z, which is a key regulator of gene expression in chloroplasts. We further demonstrate that cooperative control of chloroplast functions via the FTR/Trx and NTRC pathways is essential for plant viability. Arabidopsis double mutants impaired in FTR and NTRC expression displayed lethal phenotypes under autotrophic growth conditions. This severe growth phenotype was related to a drastic loss of photosynthetic performance. These combined results provide an expanded map of the chloroplast redox network and its biological functions.

  3. Search for an endotherm in chloroplast lamellar membranes associated with chilling-inhibition of photosynthesis.

    PubMed

    Low, P S; Ort, D R; Cramer, W A; Whitmarsh, J; Martin, B

    1984-06-01

    The phase transition of chloroplast lamellar membrane lipids has been proposed to be the underlying cause of chilling-induced inhibition of photosynthesis in sensitive plants. Differential scanning calorimetry has been used to search for any endotherms arising from lipid state changes in chloroplast lamellar membranes of the chilling-sensitive plants cantaloupe , kidney bean, domestic tomato, and soybean. For comparison, calorimetric scans of chloroplast lamellar membranes from the chilling-insensitive plants spinach, pea, and wild tomato were made. A large reversible endotherm, extending from below 10 degrees to nearly 40 degrees C, was observed in chloroplast membranes from tomatoes of both chilling-sensitive (Lycopersicon esculentum Mill. cv. Floramerica ) and chilling-insensitive (L. hirsutum LA 1361) species. A much smaller endotherm, approximately 5 to 10% of the area of that seen in the two tomato species, and extending over a similar temperature range, was detected in chloroplasts from chilling-insensitive spinach and peas, and also was generally observed in chloroplasts from chilling-sensitive cantaloupe , kidney bean, and soybean. The enthalpy of these smaller endotherms indicates that, if the endotherm arose entirely from a lipid transition, then it corresponded to the melting of less than about 10% of the total membrane polar lipid. On the basis of these data it is concluded that there is no correlation between chilling sensitivity of photosynthesis and the presence or absence of a phase transition of bulk membrane lipids of the chloroplast lamellar membrane at temperatures above 5 degrees C.

  4. Though with constraints imposed by endosymbiosis, preferential attachment is still a plausible mechanism responsible for the evolution of the chloroplast metabolic network.

    PubMed

    Wang, Z; Zhu, X-G; Chang, X; Chen, Y Z; Li, Y X; Liu, L

    2009-01-01

    Chloroplasts evolved as a result of endosymbiosis, during which sophisticated mechanisms evolved to translocate nucleus-encoded plastid-targeted enzymes into the chloroplast to form the chloroplast metabolic network. Given the constraints and complexity of endosymbiosis, will preferential attachment still be a plausible mechanism for chloroplast metabolic network evolution? We answer this question by analysing the metabolic network properties of the chloroplast and a cyanobacterium, Synechococcus sp. WH8102 (syw). First, we found that enzymes related to more ancient pathways are more connected, and synthetases have the highest connectivity. Most of the enzymes shared by the two densest cores between the chloroplast and syw are synthetases. Second, the highly conserved functional modules mainly consist of highly connected enzymes. Finally, isozymes and enzymes from endosymbiotic gene transfer (EGT) were distributed mainly in conserved modules and showed higher connectivity than nonisozymes or non-EGT enzymes. These results suggest that even with severe evolutionary constraints imposed by endosymbiosis, preferential attachment is still a plausible mechanism responsible for the evolution of the chloroplast metabolic network. However, the current analysis may not completely differentiate whether the chloroplast network properties reflect the evolution of the chloroplast network through preferential attachment or has been inherited from its cyanobacterial ancestor. To fully differentiate these two possibilities, further analyses of the metabolic network structure properties of organisms at various intermediate evolutionary stages between cyanobacteria and the chloroplast are needed.

  5. Differentiation of the seed coat and composition of the mucilage of Lepidium perfoliatum L.: a desert annual with typical myxospermy.

    PubMed

    Huang, Daihong; Wang, Cui; Yuan, Junwen; Cao, Jing; Lan, Haiyan

    2015-10-01

    Myxospermy is an important feature in seeds of many plant species grown in desert region. Fertilization can initiate differentiation of the seed coat epidermis into a specialized cell type with mucilage production. In the present study, comprehensive analyses were performed on the seed coat differentiation, mucilage production and composition, and seed germination in Lepidium perfoliatum (Brassicaceae), a desert annual with typical myxospermy in China. First, results indicated that mucilage was secreted uniformly at the outer tangential wall, resulting in compression of the cytoplasm to the bottom of the epidermal cells. Secondly, the inner tangential wall and two radial walls of the subepidermal cells were apparently thickened by production of a secondary cell wall material, which resulted in a 'typical' palisade appearance. Thirdly, immunohistochemical staining combined with the enzymatic digestion and infrared spectrum analysis of the mucilage indicated that, while one important component of the seed coat mucilage in L. perfoliatum was pectin, it also contained β-1,3-d-glucan and xyloglucan. Finally, seed germination showed that seeds with mucilage displayed significantly higher germination percentage than that of demucilaged seeds in abundant or excess water conditions. These results suggest that the possible ecological role of mucilage in L. perfoliatum is in the adaptation to habitats with well-watered and water-logged conditions, rather than water stress.

  6. Chloroplast outer envelope protein CHUP1 is essential for chloroplast anchorage to the plasma membrane and chloroplast movement.

    PubMed

    Oikawa, Kazusato; Yamasato, Akihiro; Kong, Sam-Geun; Kasahara, Masahiro; Nakai, Masato; Takahashi, Fumio; Ogura, Yasunobu; Kagawa, Takatoshi; Wada, Masamitsu

    2008-10-01

    Chloroplasts change their intracellular distribution in response to light intensity. Previously, we isolated the chloroplast unusual positioning1 (chup1) mutant of Arabidopsis (Arabidopsis thaliana). This mutant is defective in normal chloroplast relocation movement and shows aggregation of chloroplasts at the bottom of palisade mesophyll cells. The isolated gene encodes a protein with an actin-binding motif. Here, we used biochemical analyses to determine the subcellular localization of full-length CHUP1 on the chloroplast outer envelope. A CHUP1-green fluorescent protein (GFP) fusion, which was detected at the outermost part of mesophyll cell chloroplasts, complemented the chup1 phenotype, but GFP-CHUP1, which was localized mainly in the cytosol, did not. Overexpression of the N-terminal hydrophobic region (NtHR) of CHUP1 fused with GFP (NtHR-GFP) induced a chup1-like phenotype, indicating a dominant-negative effect on chloroplast relocation movement. A similar pattern was found in chloroplast OUTER ENVELOPE PROTEIN7 (OEP7)-GFP transformants, and a protein containing OEP7 in place of NtHR complemented the mutant phenotype. Physiological analyses of transgenic Arabidopsis plants expressing truncated CHUP1 in a chup1 mutant background and cytoskeletal inhibitor experiments showed that the coiled-coil region of CHUP1 anchors chloroplasts firmly on the plasma membrane, consistent with the localization of coiled-coil GFP on the plasma membrane. Thus, CHUP1 localization on chloroplasts, with the N terminus inserted into the chloroplast outer envelope and the C terminus facing the cytosol, is essential for CHUP1 function, and the coiled-coil region of CHUP1 prevents chloroplast aggregation and participates in chloroplast relocation movement.

  7. INTRAPOPULATION DIFFERENTIATION IN ANNUAL PLANTS. III. THE CONTRASTING EFFECTS OF INTRA- AND INTERSPECIFIC COMPETITION.

    PubMed

    Linhart, Yan B

    1988-09-01

    The roles of intraspecific and interspecific competition in producing differentiation within populations of Veronica peregrina were studied in two populations under controlled, greenhouse conditions. In nature, each population spans an environmental gradient across the center and sides of a temporary, vernal pool in California. Individuals at the center are subjected to intense intraspecific competition produced by high densities (to 30 seedlings/cm(2) ) generated by quasi-simultaneous germination (90% of seeds germinate in one week). Individuals at the periphery are subjected to interspecific competition with grasses, which shade out the Veronica 4-6 weeks after the onset of winter growth. I predicted that 1) when grown under immediate intraspecific competition in the greenhouse, offspring of plants from the central subpopulation (C) would perform better (i.e., grow larger and produce more seeds) than those from the periphery (P) and that 2) when grown under delayed interspecific competition provided by Agrostis tenuis and Lollium multiflorum, offspring of plants from the periphery would perform better than those from the center. Both predictions were confirmed. The center-periphery differences were pronounced and statistically significant in an undisturbed population (V-2), while in a population disturbed by yearly plowing (V-3), the differences tended to be consistent with those in V-2 but seldom significant. Distribution of variability tended to be positively skewed and/or leptokurtic in subpopulations grown under "foreign" competition (i.e., intraspecific for P plants and interspecific for C plants) but was normally distributed following exposure to "familiar" competition. Timing of competition affected many results. There were four additional significant differences between the central and peripheral subpopulations. 1) Germination rate: the faster rate in central plants can be advantageous under immediate intraspecific competition. The slower rate in

  8. Formation of putative chloroplast cytochromes in isolated developing pea chloroplasts

    SciTech Connect

    Thaver, S.S.; Bhava, D.; Castelfranco, P.A.

    1986-04-01

    In addition to chlorophyll-protein complexes, other proteins were labeled when isolated developing pea chloroplasts were incubated with (/sup 14/C)-5-aminolevulinic acid (/sup 14/C)-ALA. The major labeled band (M/sub r/ = 43 kDa by LDS-PAGE) was labeled even in the presence of chloramphenicol. Heme-dependent peroxidase activity (as detected by the tetramethyl benzidine-H/sub 2/O/sub 2/ stain) was not visibly associated with this band. The radioactive band was stable to heat, 5% HCl in acetone, and was absent if the incubation with (/sup 14/C)-5-aminolevulinic acid was carried out in the presence of N-methyl protoporphyrin IX dimethyl ester (a specific inhibitor of ferrochelatase). Organic solvent extraction procedures for the enrichment of cytochrome f from chloroplast membranes also extracted this unknown labeled product. It was concluded that this labeled product was probably a c-type cytochrome. The effect of exogenous iron, iron chelators, gabaculine (an inhibitor of ALA synthesis) and other incubation conditions upon the in vitro formation of putative chloroplast cytochromes will be discussed.

  9. Chloroplast avoidance movement reduces photodamage in plants.

    PubMed

    Kasahara, Masahiro; Kagawa, Takatoshi; Oikawa, Kazusato; Suetsugu, Noriyuki; Miyao, Mitsue; Wada, Masamitsu

    When plants are exposed to light levels higher than those required for photosynthesis, reactive oxygen species are generated in the chloroplasts and cause photodamage. This can occur even under natural growth conditions. To mitigate photodamage, plants have developed several protective mechanisms. One is chloroplast avoidance movement, in which chloroplasts move from the cell surface to the side walls of cells under high light conditions, although experimental support is still awaited. Here, using different classes of mutant defective in chloroplast avoidance movement, we show that these mutants are more susceptible to damage in high light than wild-type plants. Damage of the photosynthetic apparatus and subsequent bleaching of leaf colour and necrosis occur faster under high light conditions in the mutants than in wild-type plants. We conclude that chloroplast avoidance movement actually decreases the amount of light absorption by chloroplasts, and might therefore be important to the survival of plants under natural growth conditions.

  10. Chloroplast division checkpoint in eukaryotic algae

    PubMed Central

    Sumiya, Nobuko; Fujiwara, Takayuki; Era, Atsuko; Miyagishima, Shin-ya

    2016-01-01

    Chloroplasts evolved from a cyanobacterial endosymbiont. It is believed that the synchronization of endosymbiotic and host cell division, as is commonly seen in existing algae, was a critical step in establishing the permanent organelle. Algal cells typically contain one or only a small number of chloroplasts that divide once per host cell cycle. This division is based partly on the S-phase–specific expression of nucleus-encoded proteins that constitute the chloroplast-division machinery. In this study, using the red alga Cyanidioschyzon merolae, we show that cell-cycle progression is arrested at the prophase when chloroplast division is blocked before the formation of the chloroplast-division machinery by the overexpression of Filamenting temperature-sensitive (Fts) Z2-1 (Fts72-1), but the cell cycle progresses when chloroplast division is blocked during division-site constriction by the overexpression of either FtsZ2-1 or a dominant-negative form of dynamin-related protein 5B (DRP5B). In the cells arrested in the prophase, the increase in the cyclin B level and the migration of cyclin-dependent kinase B (CDKB) were blocked. These results suggest that chloroplast division restricts host cell-cycle progression so that the cell cycle progresses to the metaphase only when chloroplast division has commenced. Thus, chloroplast division and host cell-cycle progression are synchronized by an interactive restriction that takes place between the nucleus and the chloroplast. In addition, we observed a similar pattern of cell-cycle arrest upon the blockage of chloroplast division in the glaucophyte alga Cyanophora paradoxa, raising the possibility that the chloroplast division checkpoint contributed to the establishment of the permanent organelle. PMID:27837024

  11. Enclosure of Mitochondria by Chloroplasts 1

    PubMed Central

    Brown, R. Harold; Rigsby, Luanne L.; Akin, Danny E.

    1983-01-01

    In Panicum species of the Laxa group, some of which have characteristics intermediate to C3 and C4 photosynthesis species, some mitochondria in leaf bundle sheath cells are surrounded by chloroplasts when viewed in profile. Serial sectioning of leaves of one Laxa species, Panicum schenckii Hack, shows that these mitochondria are enclosed by chloroplasts. Complete enclosure rather than invagination also is indicated by absence of two concentric chloroplast membranes surrounding the mitochondrial profiles. Images Fig. 1 Fig. 2 Fig. 3 PMID:16662844

  12. Chloroplast actin filaments organize meshwork on the photorelocated chloroplasts in the moss Physcomitrella patens.

    PubMed

    Yamashita, Hiroko; Sato, Yoshikatsu; Kanegae, Takeshi; Kagawa, Takatoshi; Wada, Masamitsu; Kadota, Akeo

    2011-02-01

    Cytoskeleton dynamics during phototropin-dependent chloroplast photorelocation movement was analyzed in protonemal cells of actin- and microtubule-visualized lines of Physcomitrella patens expressing GFP- or tdTomato-talin and GFP-tubulin. Using newly developed epi- and trans-microbeam irradiation systems that permit fluorescence observation of the cell under blue microbeam irradiation inducing chloroplast relocation, it was revealed that meshwork of actin filaments formed at the chloroplast-accumulating area both in the avoidance and accumulation movements. The structure disappeared soon when blue microbeam was turned off, and it was not induced under red microbeam irradiation that did not evoke chloroplast relocation movement. In contrast, no apparent change in microtubule organization was detected during the movements. The actin meshwork was composed of short actin filaments distinct from the cytoplasmic long actin cables and was present between the chloroplasts and plasma membrane. The short actin filaments emerged from around the chloroplast periphery towards the center of chloroplast. Showing highly dynamic behavior, the chloroplast actin filaments (cp-actin filaments) were rapidly organized into meshwork on the chloroplast surface facing plasma membrane. The actin filament configuration on a chloroplast led to the formation of actin meshwork area in the cell as the chloroplasts arrived at and occupied the area. After establishment of the meshwork, cp-actin filaments were still highly dynamic, showing appearance, disappearance, severing and bundling of filaments. These results indicate that the cp-actin filaments have significant roles in the chloroplast movement and positioning in the cell.

  13. Chloroplast research in the genomic age.

    PubMed

    Leister, Dario

    2003-01-01

    Chloroplast research takes significant advantage of genomics and genome sequencing, and a new picture is emerging of how the chloroplast functions and communicates with other cellular compartments. In terms of evolution, it is now known that only a fraction of the many proteins of cyanobacterial origin were rerouted to higher plant plastids. Reverse genetics and novel mutant screens are providing a growing catalogue of chloroplast protein-function relationships, and the characterization of plastid-to-nucleus signalling mutants reveals cell-organelle interactions. Recent advances in transcriptomics and proteomics of the chloroplast make this organelle one of the best understood of all plant cell compartments.

  14. Isolation of Chloroplasts from Plant Protoplasts.

    PubMed

    Lung, Shiu-Cheung; Smith, Matthew D; Chuong, Simon D X

    2015-10-01

    Chloroplasts can be isolated from higher plants directly following homogenization; however, the resulting yield, purity, and intactness are often low, necessitating a large amount of starting material. This protocol is optimized to produce a high yield of pure chloroplasts from isolated Arabidopsis protoplasts. The two-part method is a simple, scaled-down, and low-cost procedure that readily provides healthy mesophyll protoplasts, which are then ruptured to release intact chloroplasts. Chloroplasts isolated using this method are competent for use in biochemical, cellular, and molecular analyses. © 2015 Cold Spring Harbor Laboratory Press.

  15. In vivo effects of NbSiR silencing on chloroplast development in Nicotiana benthamiana.

    PubMed

    Kang, Yong-Won; Lee, Jae-Yong; Jeon, Young; Cheong, Gang-Won; Kim, Moonil; Pai, Hyun-Sook

    2010-04-01

    Sulfite reductase (SiR) performs dual functions, acting as a sulfur assimilation enzyme and as a chloroplast (cp-) nucleoid binding protein. In this study, we examined the in vivo effects of SiR deficiency on chloroplast development in Nicotiana benthamiana. Virus-induced gene silencing of NbSiR resulted in leaf yellowing and growth retardation phenotypes, which were not rescued by cysteine supplementation. NbSiR:GFP fusion protein was targeted to chloroplasts and colocalized with cp-nucleoids. Recombinant full-length NbSiR protein and the C-terminal half of NbSiR possessed cp-DNA compaction activities in vitro, and expression of full-length NbSiR in E. coli caused condensation of genomic DNA. NbSiR silencing differentially affected expression of plastid-encoded genes, inhibiting expression of several genes more severely than others. In the later stages, depletion of NbSiR resulted in chloroplast ablation. In NbSiR-silenced plants, enlarged cp-nucleoids containing an increased amount of cp-DNA were observed in the middle of the abnormal chloroplasts, and the cp-DNAs were predominantly of subgenomic sizes based on pulse field gel electrophoresis. The abnormal chloroplasts developed prolamellar body-like cubic lipid structures in the light without accumulating NADPH:protochlorophyllide oxidoreductase proteins. Our results suggest that NbSiR plays a role in cp-nucleoid metabolism, plastid gene expression, and thylakoid membrane development.

  16. GROWTH REGULATING FACTOR5 stimulates Arabidopsis chloroplast division, photosynthesis, and leaf longevity.

    PubMed

    Vercruyssen, Liesbeth; Tognetti, Vanesa B; Gonzalez, Nathalie; Van Dingenen, Judith; De Milde, Liesbeth; Bielach, Agnieszka; De Rycke, Riet; Van Breusegem, Frank; Inzé, Dirk

    2015-03-01

    Arabidopsis (Arabidopsis thaliana) leaf development relies on subsequent phases of cell proliferation and cell expansion. During the proliferation phase, chloroplasts need to divide extensively, and during the transition from cell proliferation to expansion, they differentiate into photosynthetically active chloroplasts, providing the plant with energy. The transcription factor GROWTH REGULATING FACTOR5 (GRF5) promotes the duration of the cell proliferation period during leaf development. Here, it is shown that GRF5 also stimulates chloroplast division, resulting in a higher chloroplast number per cell with a concomitant increase in chlorophyll levels in 35S:GRF5 leaves, which can sustain higher rates of photosynthesis. Moreover, 35S:GRF5 plants show delayed leaf senescence and are more tolerant for growth on nitrogen-depleted medium. Cytokinins also stimulate leaf growth in part by extending the cell proliferation phase, simultaneously delaying the onset of the cell expansion phase. In addition, cytokinins are known to be involved in chloroplast development, nitrogen signaling, and senescence. Evidence is provided that GRF5 and cytokinins synergistically enhance cell division and chlorophyll retention after dark-induced senescence, which suggests that they also cooperate to stimulate chloroplast division and nitrogen assimilation. Taken together with the increased leaf size, ectopic expression of GRF5 has great potential to improve plant productivity.

  17. GROWTH REGULATING FACTOR5 Stimulates Arabidopsis Chloroplast Division, Photosynthesis, and Leaf Longevity1[OPEN

    PubMed Central

    Vercruyssen, Liesbeth; Tognetti, Vanesa B.; Gonzalez, Nathalie; Van Dingenen, Judith; De Milde, Liesbeth; Bielach, Agnieszka; De Rycke, Riet; Van Breusegem, Frank; Inzé, Dirk

    2015-01-01

    Arabidopsis (Arabidopsis thaliana) leaf development relies on subsequent phases of cell proliferation and cell expansion. During the proliferation phase, chloroplasts need to divide extensively, and during the transition from cell proliferation to expansion, they differentiate into photosynthetically active chloroplasts, providing the plant with energy. The transcription factor GROWTH REGULATING FACTOR5 (GRF5) promotes the duration of the cell proliferation period during leaf development. Here, it is shown that GRF5 also stimulates chloroplast division, resulting in a higher chloroplast number per cell with a concomitant increase in chlorophyll levels in 35S:GRF5 leaves, which can sustain higher rates of photosynthesis. Moreover, 35S:GRF5 plants show delayed leaf senescence and are more tolerant for growth on nitrogen-depleted medium. Cytokinins also stimulate leaf growth in part by extending the cell proliferation phase, simultaneously delaying the onset of the cell expansion phase. In addition, cytokinins are known to be involved in chloroplast development, nitrogen signaling, and senescence. Evidence is provided that GRF5 and cytokinins synergistically enhance cell division and chlorophyll retention after dark-induced senescence, which suggests that they also cooperate to stimulate chloroplast division and nitrogen assimilation. Taken together with the increased leaf size, ectopic expression of GRF5 has great potential to improve plant productivity. PMID:25604530

  18. A large population of small chloroplasts in tobacco leaf cells allows more effective chloroplast movement than a few enlarged chloroplasts.

    PubMed

    Jeong, Won Joong; Park, Youn-Il; Suh, KyeHong; Raven, John A; Yoo, Ook Joon; Liu, Jang Ryol

    2002-05-01

    We generated transgenic tobacco (Nicotiana tabacum cv Xanthi) plants that contained only one to three enlarged chloroplasts per leaf mesophyll cell by introducing NtFtsZ1-2, a cDNA for plastid division. These plants were used to investigate the advantages of having a large population of small chloroplasts rather than a few enlarged chloroplasts in a leaf mesophyll cell. Despite the similarities in photosynthetic components and ultrastructure of photosynthetic machinery between wild-type and transgenic plants, the overall growth of transgenic plants under low- and high-light conditions was retarded. In wild-type plants, the chloroplasts moved toward the face position under low light and toward the profile position under high-light conditions. However, chloroplast rearrangement in transgenic plants in response to light conditions was not evident. In addition, transgenic plant leaves showed greatly diminished changes in leaf transmittance values under both light conditions, indicating that chloroplast rearrangement was severely retarded. Therefore, under low-light conditions the incomplete face position of the enlarged chloroplasts results in decreased absorbance of light energy. This, in turn, reduces plant growth. Under high-light conditions, the amount of absorbed light exceeds the photosynthetic utilization capacity due to the incomplete profile position of the enlarged chloroplasts, resulting in photodamage to the photosynthetic machinery, and decreased growth. The presence of a large number of small and/or rapidly moving chloroplasts in the cells of higher land plants permits more effective chloroplast phototaxis and, hence, allows more efficient utilization of low-incident photon flux densities. The photosynthetic apparatus is, consequently, protected from damage under high-incident photon flux densities.

  19. Chloroplast division: a work of ARTEMIS.

    PubMed

    Osteryoung, Katherine W

    2002-12-23

    Chloroplasts contain three membrane systems that constrict together during division of the organelle. A newly identified protein, ARTEMIS, may shed light on the nuclear control of chloroplast division, and also on the mechanism of thylakoid membrane fission and how this is coordinated with fission of the two envelope membranes.

  20. Insights into chloroplast biogenesis and development.

    PubMed

    Pogson, Barry J; Ganguly, Diep; Albrecht-Borth, Verónica

    2015-09-01

    In recent years many advances have been made to obtain insight into chloroplast biogenesis and development. In plants several plastids types exist such as the proplastid (which is the progenitor of all plastids), leucoplasts (group of colourless plastids important for storage including elaioplasts (lipids), amyloplasts (starch) or proteinoplasts (proteins)), chromoplasts (yellow to orange-coloured due to carotenoids, in flowers or in old leaves as gerontoplasts), and the green chloroplasts. Chloroplasts are indispensable for plant development; not only by performing photosynthesis and thus rendering the plant photoautotrophic, but also for biochemical processes (which in some instances can also take place in other plastids types), such as the synthesis of pigments, lipids, and plant hormones and sensing environmental stimuli. Although we understand many aspects of these processes there are gaps in our understanding of the establishment of functional chloroplasts and their regulation. Why is that so? Even though chloroplast function is comparable in all plants and most of the algae, ferns and moss, detailed analyses have revealed many differences, specifically with respect to its biogenesis. As an update to our prior review on the genetic analysis of chloroplast biogenesis and development [1] herein we will focus on recent advances in Angiosperms (monocotyledonous and dicotyledonous plants) that provide novel insights and highlight the challenges and prospects for unravelling the regulation of chloroplast biogenesis specifically during the establishment of the young plants. This article is part of a Special Issue entitled: Chloroplast Biogenesis.

  1. Molecular basis of chloroplast photorelocation movement.

    PubMed

    Kong, Sam-Geun; Wada, Masamitsu

    2016-03-01

    Chloroplast photorelocation movement is an essential physiological response for sessile plant survival and the optimization of photosynthetic ability. Simple but effective experiments on the physiological, cell biological and molecular genetic aspects have been widely used to investigate the signaling components of chloroplast photorelocation movement in Arabidopsis for the past few decades. Although recent knowledge on chloroplast photorelocation movement has led us to a deeper understanding of its physiological and molecular basis, the biochemical roles of the downstream factors remain largely unknown. In this review, we briefly summarize recent advances regarding chloroplast photorelocation movement and propose that a new high-resolution approach is necessary to investigate the molecular mechanism underlying actin-based chloroplast photorelocation movement.

  2. An analysis of Echinacea chloroplast genomes: Implications for future botanical identification.

    PubMed

    Zhang, Ning; Erickson, David L; Ramachandran, Padmini; Ottesen, Andrea R; Timme, Ruth E; Funk, Vicki A; Luo, Yan; Handy, Sara M

    2017-03-16

    Echinacea is a common botanical used in dietary supplements, primarily to treat upper respiratory tract infections and to support immune function. There are currently thought to be nine species in the genus Echinacea. Due to very low molecular divergence among sister species, traditional DNA barcoding has not been successful for differentiation of Echinacea species. Here, we present the use of full chloroplast genomes to distinguish between all 9 reported species. Total DNA was extracted from specimens stored at the National Museum of Natural History, Smithsonian Institution, which had been collected from the wild with species identification documented by experts in the field. We used Next Generation Sequencing (NGS) and CLC Genomics Workbench to assemble complete chloroplast genomes for all nine species. Full chloroplasts unambiguously differentiated all nine species, compared with the very few single nucleotide polymorphisms (SNPs) available with core DNA barcoding markers. SNPs for any two Echinacea chloroplast genomes ranged from 181 to 910, and provided robust data for unambiguous species delimitation. Implications for DNA-based species identification assays derived from chloroplast genome sequences are discussed in light of product safety, adulteration and quality issues.

  3. Analysis of chloroplast movement and relocation in Arabidopsis.

    PubMed

    Wada, Masamitsu; Kong, Sam-Geun

    2011-01-01

    Chloroplast photorelocation movement is essential for the sessile plant survival and plays a role for efficient photosynthesis and avoiding photodamage of chloroplasts. There are several ways to observe or detect chloroplast movement directly or indirectly. Here, techniques for the induction of chloroplast movement and how to detect the responses, as well as various points of attention and advice for the experiments, are described.

  4. Rapid isolation of intact chloroplasts from spinach leaves.

    PubMed

    Joly, David; Carpentier, Robert

    2011-01-01

    In this chapter, a rapid method to isolate intact chloroplasts from spinach leaves is described. Intact chloroplasts are isolated using two short centrifugation steps and avoiding the use of percoll gradient. Intactness of chloroplast is evaluated by the inability of potassium ferricyanide to enter inside the chloroplasts and to act as an electron acceptor for photosystem II.

  5. Mitochondrion-to-Chloroplast DNA Transfers and Intragenomic Proliferation of Chloroplast Group II Introns in Gloeotilopsis Green Algae (Ulotrichales, Ulvophyceae).

    PubMed

    Turmel, Monique; Otis, Christian; Lemieux, Claude

    2016-09-19

    To probe organelle genome evolution in the Ulvales/Ulotrichales clade, the newly sequenced chloroplast and mitochondrial genomes of Gloeotilopsis planctonica and Gloeotilopsis sarcinoidea (Ulotrichales) were compared with those of Pseudendoclonium akinetum (Ulotrichales) and of the few other green algae previously sampled in the Ulvophyceae. At 105,236 bp, the G planctonica mitochondrial DNA (mtDNA) is the largest mitochondrial genome reported so far among chlorophytes, whereas the 221,431-bp G planctonica and 262,888-bp G sarcinoidea chloroplast DNAs (cpDNAs) are the largest chloroplast genomes analyzed among the Ulvophyceae. Gains of non-coding sequences largely account for the expansion of these genomes. Both Gloeotilopsis cpDNAs lack the inverted repeat (IR) typically found in green plants, indicating that two independent IR losses occurred in the Ulvales/Ulotrichales. Our comparison of the Pseudendoclonium and Gloeotilopsis cpDNAs offered clues regarding the mechanism of IR loss in the Ulotrichales, suggesting that internal sequences from the rDNA operon were differentially lost from the two original IR copies during this process. Our analyses also unveiled a number of genetic novelties. Short mtDNA fragments were discovered in two distinct regions of the G sarcinoidea cpDNA, providing the first evidence for intracellular inter-organelle gene migration in green algae. We identified for the first time in green algal organelles, group II introns with LAGLIDADG ORFs as well as group II introns inserted into untranslated gene regions. We discovered many group II introns occupying sites not previously documented for the chloroplast genome and demonstrated that a number of them arose by intragenomic proliferation, most likely through retrohoming. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  6. Plastidic Isoprenoid Synthesis during Chloroplast Development 1

    PubMed Central

    Heintze, Adolf; Görlach, Jörn; Leuschner, Carola; Hoppe, Petra; Hagelstein, Petra; Schulze-Siebert, Detlef; Schultz, Gernot

    1990-01-01

    The chloroplast isoprenoid synthesis of very young leaves is supplied by the plastidic CO2 → pyruvate → acetyl-coenzyme A (C3 → C2) metabolism (D Schulze-Siebert, G Schultz [1987] Plant Physiol 84: 1233-1237) and occurs via the plastidic mevalonate pathway. The plastidic C3 → C2 metabolism and/or plastidic mevalonate pathway of barley (Hordeum vulgare L.) seedlings changes from maximal activity at the leaf base (containing developing chloroplasts with incomplete thylakoid stacking but a considerable rate of photosynthetic CO2-fixation) almost to ineffectivity at the leaf tip (containing mature chloroplasts with maximal photosynthetic activity). The ability to import isopentenyl diphosphate from the extraplastidic space gradually increases to substitute for the loss of endogenous intermediate supply for chloroplast isoprenoid synthesis (change from autonomic to division-of-labor stage). Fatty acid synthesis from NaH14CO3 decreases in the same manner as shown for leaf sections and chloroplasts isolated from these. Evidence has been obtained for a drastic decrease of pyruvate decarboxylase-dehydrogenase activity during chloroplast development compared with other anabolic chloroplast pathways (synthesis of aromatic amino acid and branched chain amino acids). The noncompetition of pyruvate and acetate in isotopic dilution studies indicates that both a pyruvate-derived and an acetate-derived compound are simultaneously needed to form introductory intermediates of the mevalonate pathway, presumably acetoacetyl-coenzyme A. PMID:16667567

  7. Determining the location of an Arabidopsis chloroplast protein using in vitro import followed by fractionation and alkaline extraction.

    PubMed

    Chu, Chiung-Chih; Li, Hsou-Min

    2011-01-01

    Chloroplasts have one of the most complicated structures among organelles. They have three membrane systems, the outer and inner envelope membranes and the thylakoid membrane, which enclose three aqueous spaces: the intermembrane space between the two envelope membranes, the stroma, and the thylakoid lumen. Each of the chloroplast's sub-organellar compartments houses a distinct set of proteins that perform distinct functions. Determining the sub-organellar location of a protein in the chloroplast is vital for understanding or verifying the function of the protein. Here, we present protocols for determining the sub-organellar location of a chloroplast protein. The protein of interest is synthesized and labeled with [(35)S]methionine by an in vitro translation system, and imported into isolated chloroplasts. The location of the protein is then identified by fractionation of the chloroplasts through differential and sucrose step-gradient centrifugations. The various sub-chloroplast fractions are analyzed by SDS-PAGE and autoradiography, so no specific antibody against the protein of interest is required. For membrane proteins, an alkaline extraction protocol is provided to further determine whether the protein is a peripheral or an integral membrane protein. The fractionation and extraction procedures presented can also be used in conjunction with immunoblotting, if an antibody against the protein of interest is available, enabling analyses of endogenous proteins.

  8. Bizonoplast, a unique chloroplast in the epidermal cells of microphylls in the shade plant Selaginella erythropus (Selaginellaceae).

    PubMed

    Sheue, Chiou-Rong; Sarafis, Vassilios; Kiew, Ruth; Liu, Ho-Yih; Salino, Alexandre; Kuo-Huang, Ling-Long; Yang, Yuen-Po; Tsai, Chi-Chu; Lin, Chun-Hung; Yong, Jean W H; Ku, Maurice S B

    2007-12-01

    Study of the unique leaf anatomy and chloroplast structure in shade-adapted plants will aid our understanding of how plants use light efficiently in low light environments. Unusual chloroplasts in terms of size and thylakoid membrane stacking have been described previously in several deep-shade plants. In this study, a single giant cup-shaped chloroplast, termed a bizonoplast, was found in the abaxial epidermal cells of the dorsal microphylls and the adaxial epidermal cells of the ventral microphylls in the deep-shade spike moss Selaginella erythropus. Bizonoplasts are dimorphic in ultrastructure: the upper zone is occupied by numerous layers of 2-4 stacked thylakoid membranes while the lower zone contains both unstacked stromal thylakoids and thylakoid lamellae stacked in normal grana structure oriented in different directions. In contrast, other cell types in the microphylls contain chloroplasts with typical structure. This unique chloroplast has not been reported from any other species. The enlargement of epidermal cells into funnel-shaped, photosynthetic cells coupled with specific localization of a large bizonoplast in the lower part of the cells and differential modification in ultrastructure within the chloroplast may allow the plant to better adapt to low light. Further experiments are required to determine whether this shade-adapted organism derives any evolutionary or ecophysiological fitness from these unique chloroplasts.

  9. The DnaJ OsDjA7/8 is essential for chloroplast development in rice (Oryza sativa).

    PubMed

    Zhu, Xiaobo; Liang, Sihui; Yin, Junjie; Yuan, Can; Wang, Jing; Li, Weitao; He, Min; Wang, Jichun; Chen, Weilan; Ma, Bingtian; Wang, Yuping; Qin, Peng; Li, Shigui; Chen, Xuewei

    2015-12-10

    DnaJ proteins belong to chaperones of Hsp40 family that ubiquitously participate in various cellular processes. Previous studies have shown chloroplast-targeted DnaJs are involved in the development of chloroplast in some plant species. However, little is known about the function of DnaJs in rice, one of the main staple crops. In this study, we characterized a type I DnaJ protein OsDjA7/8. We found that the gene OsDjA7/8 was expressed in all collected tissues, with a priority in the vigorous growth leaf. Subcellular localization revealed that the protein OsDjA7/8 was mainly distributed in chloroplast. Reduced expression of OsDjA7/8 in rice led to albino lethal at the seedling stage. Transmission electron microscopy observation showed that the chloroplast structures were abnormally developed in the plants silenced for OsDjA7/8. In addition, the transcriptional expression of the genes tightly associated with the development of chloroplast was deeply reduced in the plants silenced for OsDjA7/8. Collectively, our study reveals that OsDjA7/8 encodes a chloroplast-localized protein and is essential for chloroplast development and differentiation in rice.

  10. PHYSICAL AND CHEMICAL CHARACTERISTICS OF CHLOROPLAST FRAGMENTS. APPLIED RESEARCH CONCERNING ARTIFICIAL PHOTOSYNTHESIS

    DTIC Science & Technology

    Chloroplasts isolated from spinach leaves were physically fragmented and then fractionated by differential centrifugation. A high-activity fraction...high chlorophyll -to-protein ratio. Plastoquinone was present in high concentration. Extraction of plastoquinone from CF(20-50) inhibited Hill activity

  11. Rangewide Genetic Variation in Coast Redwood Populations at a Chloroplast Microsatellite Locus

    Treesearch

    Chris Brinegar

    2012-01-01

    Old growth and second growth populations of coast redwood (Sequoia sempervirens) were sampled at 10 locations throughout its range and analyzed at a highly variable chloroplast microsatellite locus. Very low FST values indicated that there was no significant genetic differentiation between adjacent old growth and second growth populations at each location. Genetic...

  12. Chloroplast DNA Replication Is Regulated by the Redox State Independently of Chloroplast Division in Chlamydomonas reinhardtii1[C][OA

    PubMed Central

    Kabeya, Yukihiro; Miyagishima, Shin-ya

    2013-01-01

    Chloroplasts arose from a cyanobacterial endosymbiont and multiply by division. In algal cells, chloroplast division is regulated by the cell cycle so as to occur only once, in the S phase. Chloroplasts possess multiple copies of their own genome that must be replicated during chloroplast proliferation. In order to examine how chloroplast DNA replication is regulated in the green alga Chlamydomonas reinhardtii, we first asked whether it is regulated by the cell cycle, as is the case for chloroplast division. Chloroplast DNA is replicated in the light and not the dark phase, independent of the cell cycle or the timing of chloroplast division in photoautotrophic culture. Inhibition of photosynthetic electron transfer blocked chloroplast DNA replication. However, chloroplast DNA was replicated when the cells were grown heterotrophically in the dark, raising the possibility that chloroplast DNA replication is coupled with the reducing power supplied by photosynthesis or the uptake of acetate. When dimethylthiourea, a reactive oxygen species scavenger, was added to the photoautotrophic culture, chloroplast DNA was replicated even in the dark. In contrast, when methylviologen, a reactive oxygen species inducer, was added, chloroplast DNA was not replicated in the light. Moreover, the chloroplast DNA replication activity in both the isolated chloroplasts and nucleoids was increased by dithiothreitol, while it was repressed by diamide, a specific thiol-oxidizing reagent. These results suggest that chloroplast DNA replication is regulated by the redox state that is sensed by the nucleoids and that the disulfide bonds in nucleoid-associated proteins are involved in this regulatory activity. PMID:23447524

  13. Comparative proteomics of chloroplasts envelopes from bundle sheath and mesophyll chloroplasts reveals novel membrane proteins with a possible role in c4-related metabolite fluxes and development.

    PubMed

    Manandhar-Shrestha, K; Tamot, B; Pratt, E P S; Saitie, S; Bräutigam, A; Weber, A P M; Hoffmann-Benning, Susanne

    2013-01-01

    As the world population grows, our need for food increases drastically. Limited amounts of arable land lead to a competition between food and fuel crops, while changes in the global climate may impact future crop yields. Thus, a second "green revolution" will need a better understanding of the processes essential for plant growth and development. One approach toward the solution of this problem is to better understand regulatory and transport processes in C4 plants. C4 plants display an up to 10-fold higher apparent CO2 assimilation and higher yields while maintaining high water use efficiency. This requires differential regulation of mesophyll (M) and bundle sheath (BS) chloroplast development as well as higher metabolic fluxes of photosynthetic intermediates between cells and particularly across chloroplast envelopes. While previous analyses of overall chloroplast membranes have yielded significant insight, our comparative proteomics approach using enriched BS and M chloroplast envelopes of Zea mays allowed us to identify 37 proteins of unknown function that have not been seen in these earlier studies. We identified 280 proteins, 84% of which are known/predicted to be present in chloroplasts. Seventy-four percent have a known or predicted membrane association. Twenty-one membrane proteins were 2-15 times more abundant in BS cells, while 36 of the proteins were more abundant in M chloroplast envelopes. These proteins could represent additional candidates of proteins essential for development or metabolite transport processes in C4 plants. RT-PCR confirmed differential expression of 13 candidate genes. Chloroplast association for seven proteins was confirmed using YFP/GFP labeling. Gene expression of four putative transporters was examined throughout the leaf and during the greening of leaves. Genes for a PIC-like protein and an ER-AP-like protein show an early transient increase in gene expression during the transition to light. In addition, PIC gene expression is

  14. Particle Movements in Chloroplast Membranes: Quantitative Measurements of Membrane Fluidity by the Freeze-Fracture Technique

    PubMed Central

    Ojakian, George K.; Satir, Peter

    1974-01-01

    Stacked chloroplast membranes isolated from Chlamydomonas reinhardtii have differentiated particle arrays when examined by freeze-fracture electron microscopy. When the membranes are isolated unstacked, these particle arrays are lost and the fracture faces have a homogeneous appearance. The changes in appearance are due to rearrangement of existing membrane components by lateral particle movements in the plane of the fluid chloroplast membranes, since quantitative measurements demonstrate almost complete conservation of numbers and sizes of membrane particles during experimentally controlled stacking and unstacking. Images PMID:4525315

  15. Transcriptome and proteomic analyses reveal multiple differences associated with chloroplast development in the spaceflight-induced wheat albino mutant mta.

    PubMed

    Shi, Kui; Gu, Jiayu; Guo, Huijun; Zhao, Linshu; Xie, Yongdun; Xiong, Hongchun; Li, Junhui; Zhao, Shirong; Song, Xiyun; Liu, Luxiang

    2017-01-01

    Chloroplast development is an integral part of plant survival and growth, and occurs in parallel with chlorophyll biosynthesis. However, little is known about the mechanisms underlying chloroplast development in hexaploid wheat. Here, we obtained a spaceflight-induced wheat albino mutant mta. Chloroplast ultra-structural observation showed that chloroplasts of mta exhibit abnormal morphology and distribution compared to wild type. Photosynthetic pigments content was also significantly decreased in mta. Transcriptome and chloroplast proteome profiling of mta and wild type were done to identify differentially expressed genes (DEGs) and proteins (DEPs), respectively. In total 4,588 DEGs including 1,980 up- and 2,608 down-regulated, and 48 chloroplast DEPs including 15 up- and 33 down-regulated were identified in mta. Classification of DEGs revealed that most were involved in chloroplast development, chlorophyll biosynthesis, or photosynthesis. Besides, transcription factors such as PIF3, GLK and MYB which might participate in those pathways were also identified. The correlation analysis between DEGs and DEPs revealed that the transcript-to-protein in abundance was functioned into photosynthesis and chloroplast relevant groups. Real time qPCR analysis validated that the expression level of genes encoding photosynthetic proteins was significantly decreased in mta. Together, our results suggest that the molecular mechanism for albino leaf color formation in mta is a thoroughly regulated and complicated process. The combined analysis of transcriptome and proteome afford comprehensive information for further research on chloroplast development mechanism in wheat. And spaceflight provides a potential means for mutagenesis in crop breeding.

  16. Salt-stress-responsive chloroplast proteins in Brassica juncea genotypes with contrasting salt tolerance and their quantitative PCR analysis.

    PubMed

    Yousuf, Peerzada Yasir; Ahmad, Altaf; Aref, Ibrahim M; Ozturk, Munir; Hemant; Ganie, Arshid Hussain; Iqbal, Muhammad

    2016-11-01

    Brassica juncea is mainly cultivated in the arid and semi-arid regions of India where its production is significantly affected by soil salinity. Adequate knowledge of the mechanisms underlying the salt tolerance at sub-cellular levels must aid in developing the salt-tolerant plants. A proper functioning of chloroplasts under salinity conditions is highly desirable to maintain crop productivity. The adaptive molecular mechanisms offered by plants at the chloroplast level to cope with salinity stress must be a prime target in developing the salt-tolerant plants. In the present study, we have analyzed differential expression of chloroplast proteins in two Brassica juncea genotypes, Pusa Agrani (salt-sensitive) and CS-54 (salt-tolerant), under the effect of sodium chloride. The chloroplast proteins were isolated and resolved using 2DE, which facilitated identification and quantification of 12 proteins that differed in expression in the salt-tolerant and salt-sensitive genotypes. The identified proteins were related to a variety of chloroplast-associated molecular processes, including oxygen-evolving process, PS I and PS II functioning, Calvin cycle and redox homeostasis. Expression analysis of genes encoding differentially expressed proteins through real time PCR supported our findings with proteomic analysis. The study indicates that modulating the expression of chloroplast proteins associated with stabilization of photosystems and oxidative defence plays imperative roles in adaptation to salt stress.

  17. Importance of phosphatidylcholine on the chloroplast surface.

    PubMed

    Botella, César; Jouhet, Juliette; Block, Maryse A

    2017-01-01

    In plant cells, phosphatidylcholine (PC) is a major glycerolipid of most membranes but practically lacking from the plastid internal membranes. In chloroplasts, PC is absent from the thylakoids and the inner envelope membrane. It is however the main component of the outer envelope membrane, where it exclusively distributes in the outer monolayer. This unique distribution is likely related with operational compartmentalization of plant lipid metabolism. In this review, we summarize the different mechanisms involved in homeostasis of PC in plant cells. The specific origin of chloroplast PC is examined and the involvement of the P4-ATPase family of phospholipid flippases (ALA) is considered with a special attention to the recently reported effect of the endoplasmic reticulum-localized ALA10 on modification of chloroplast PC desaturation. The different possible roles of chloroplast PC are then discussed and analyzed in consideration of plant physiology.

  18. Proteomic comparison reveals the contribution of chloroplast to salt tolerance of a wheat introgression line

    PubMed Central

    Xu, Wenjing; Lv, Hongjun; Zhao, Mingming; Li, Yongchao; Qi, Yueying; Peng, Zhenying; Xia, Guangmin; Wang, Mengcheng

    2016-01-01

    We previously bred a salt tolerant wheat cv. SR3 with bread wheat cv. JN177 as the parent via asymmetric somatic hybridization, and found that the tolerance is partially attributed to the superior photosynthesis capacity. Here, we compared the proteomes of two cultivars to unravel the basis of superior photosynthesis capacity. In the maps of two dimensional difference gel electrophoresis (2D-DIGE), there were 26 differentially expressed proteins (DEPs), including 18 cultivar-based and 8 stress-responsive ones. 21 of 26 DEPs were identified and classified into four categories, including photosynthesis, photosynthesis system stability, linolenic acid metabolism, and protein synthesis in chloroplast. The chloroplast localization of some DEPs confirmed that the identified DEPs function in the chloroplast. The overexpression of a DEP enhanced salt tolerance in Arabidopsis thaliana. In line with these data, it is concluded that the contribution of chloroplast to high salinity tolerance of wheat cv. SR3 appears to include higher photosynthesis efficiency by promoting system protection and ROS clearance, stronger production of phytohormone JA by enhancing metabolism activity, and modulating the in chloroplast synthesis of proteins. PMID:27562633

  19. Proteomic analysis of changes in the Kandelia candel chloroplast proteins reveals pathways associated with salt tolerance.

    PubMed

    Wang, Lingxia; Pan, Dezhuo; Li, Jian; Tan, Fanglin; Hoffmann-Benning, Susanne; Liang, Wenyu; Chen, Wei

    2015-02-01

    The plant chloroplast is one of the most sensitive organelles in response to salt stress. Chloroplast proteins extracted from seedling leaves were separated by two-dimensional gel electrophoresis (2-DE). More than 600 protein spots could be distinguished on each gel. Fifty-eight differentially expressed protein spots were detected, of which 46 could be identified through matrix-assisted laser desorption ionization time-of-flight/time-of-flight mass spectrometry (MALDI-TOF/TOF-MS). These proteins were found to be involved in multiple aspects of chloroplast metabolism pathways such as photosynthesis, ATP synthesis, detoxification and antioxidation processes, nitrogen assimilation and fixation, protein metabolism, and tetrapyrrole biosynthesis. The results indicated that K. candel could withstand up to 500 mM NaCl stress for a measured period of 3 days, by maintaining normal or high photosynthetic electron transfer efficiency and an only slightly stimulated Calvin cycle. Meanwhile, we found that ROS scavenging, nitrogen assimilation, protein degradation and chaperone function in chloroplasts were also of importance for salt tolerance of K. candel. The ultrastructural and physiological data agree with chloroplast proteome results. These findings allow further exploration of our knowledge on salt adaptation in woody halophytes and may contribute to the development of more salt-tolerant plants in the future.

  20. Effects of Pronase on Isolated Chloroplasts 1

    PubMed Central

    Fish, Leonard; Franceschi, Vincent R.; Stocking, C. Ralph

    1979-01-01

    Subjecting isolated spinach chloroplasts to mild proteolysis (10-minute incubation at 20 C in 500 micrograms per milliliter pronase) caused chloroplast clumping but did not affect their integrity as measured by their ability to carry out light stimulated, glycerate-3-P-dependent O2 evolution. Transmission electron microscopy revealed no detectable differences between the control and treated plastids. Mild proteolysis inactivated exogenously added pyruvate kinase and should be a useful technique in certain enzyme distribution studies. Images PMID:16661083

  1. Essentials of Proteolytic Machineries in Chloroplasts.

    PubMed

    Nishimura, Kenji; Kato, Yusuke; Sakamoto, Wataru

    2017-01-09

    Plastids are unique organelles that can alter their structure and function in response to environmental and developmental stimuli. Chloroplasts are one type of plastid and are the sites for various metabolic processes, including photosynthesis. For optimal photosynthetic activity, the chloroplast proteome must be properly shaped and maintained through regulated proteolysis and protein quality control mechanisms. Enzymatic functions and activities are conferred by protein maturation processes involving consecutive proteolytic reactions. Protein abundances are optimized by the balanced protein synthesis and degradation, which is depending on the metabolic status. Malfunctioning proteins are promptly degraded. Twenty chloroplast proteolytic machineries have been characterized to date. Specifically, processing peptidases and energy-driven processive proteases are the major players in chloroplast proteome biogenesis, remodeling, and maintenance. Recently identified putative proteases are potential regulators of photosynthetic functions. Here we provide an updated, comprehensive overview of chloroplast protein degradation machineries and discuss their importance for photosynthesis. Wherever possible, we also provide structural insights into chloroplast proteases that implement regulated proteolysis of substrate proteins/peptides. Copyright © 2017 The Author. Published by Elsevier Inc. All rights reserved.

  2. Oxygenic photosynthesis and the distribution of chloroplasts.

    PubMed

    Gantt, Elisabeth

    2011-01-01

    The integrated functioning of two photosystems (I and II) whether in cyanobacteria or in chloroplasts is the outstanding sign of a common ancestral origin. Many variations on the basic theme are currently evident in oxygenic photosynthetic organisms whether they are prokaryotes, unicellular, or multicellular. By conservative estimates, oxygenic photosynthesis has been around for at least ca. 2.2-2.7 billions years, consistent with cyanobacteria-type microfossils, biomarkers, and an atmospheric rise in oxygen to less than 1.0% of the present concentration. The presumptions of chloroplast formation by the cyanobacterial uptake into a eukaryote prior to 1.6 BYa ago are confounded by assumptions of host type(s) and potential tolerance of oxygen toxicity. The attempted dating and interrelationships of particular chloroplasts in various plant or animal lineages has relied heavily on phylogenomic analysis and evaluations that have been difficult to confirm separately. Many variations occur in algal groups, involving the type and number of accessory pigments, and the number(s) of membranes (2-4) enclosing a chloroplast, which can both help and complicate inferences made about early or late origins of chloroplasts. Integration of updated phylogenomics with physiological and cytological observations remains a special challenge, but could lead to more accurate assumptions of initial and extant endosymbiotic event(s) leading toward stable chloroplast associations.

  3. Export of carbon from chloroplasts at night

    SciTech Connect

    Schleucher, J.; Vanderveer, P.J.; Sharkey, T.D.

    1998-12-01

    Hexose export from chloroplasts at night has been inferred in previous studies of mutant and transgenic plants. The authors have tested whether hexose export is the normal route of carbon export from chloroplasts at night. The authors used nuclear magnetic resonance to distinguish glucose (Glc) made from hexose export and Glc made from triose export. Glc synthesized in vitro from fructose-6-phosphate in the presence of deuterium-labeled water had deuterium incorporated at C-2, whereas synthesis from triose phosphates caused C-2 through C-5 to become deuterated. In both tomato (Lycopersicon esculentum L.) and bean (phaseolus vulgaris L.), Glc from sucrose made at night in the presence of deuterium-enriched water was deuterated only in the C-2 position, indicating that >75% of carbon is exported as hexoses at night. In darkness the phosphate in the cytosol was 28 mM, whereas that in the chloroplasts was 5 mW, but hexose phosphates were 10-fold higher in the cytosol than in the chloroplasts. Therefore, hexose phosphates would not move out of chloroplasts without the input of energy. The authors conclude that most carbon leaves chloroplasts at night as Glc, maltose, or higher maltodextrins under normal conditions.

  4. A Model of Chloroplast Growth Regulation in Mesophyll Cells.

    PubMed

    Paton, Kelly M; Anderson, Lisa; Flottat, Pauline; Cytrynbaum, Eric N

    2015-09-01

    Chloroplasts regulate their growth to optimize photosynthesis. Quantitative data show that the ratio of total chloroplast area to mesophyll cell area is constant across different cells within a single species and also across species. Wild-type chloroplasts exhibit little scatter around this trend; highly irregularly shaped mutant chloroplasts exhibit more scatter. Here we propose a model motivated by a bacterial quorum-sensing model consisting of a switch-like signaling network that turns off chloroplast growth. We calculated the dependence of the location of the relevant saddle-node bifurcation on the geometry of the chloroplasts. Our model exhibits a linear trend, with linearly growing scatter dependent on chloroplast shape, consistent with the data. When modeled chloroplasts are of a shape that grows with a constant area-to-volume ratio (disks, cylinders), we find a linear trend with minimal scatter. Chloroplasts with area and volume that do not grow proportionally (spheres) exhibit a linear trend with additional scatter.

  5. Chloroplast proteome response to drought stress and recovery in tomato (Solanum lycopersicum L.).

    PubMed

    Tamburino, Rachele; Vitale, Monica; Ruggiero, Alessandra; Sassi, Mauro; Sannino, Lorenza; Arena, Simona; Costa, Antonello; Batelli, Giorgia; Zambrano, Nicola; Scaloni, Andrea; Grillo, Stefania; Scotti, Nunzia

    2017-02-10

    Drought is a major constraint for plant growth and crop productivity that is receiving an increased attention due to global climate changes. Chloroplasts act as environmental sensors, however, only partial information is available on stress-induced mechanisms within plastids. Here, we investigated the chloroplast response to a severe drought treatment and a subsequent recovery cycle in tomato through physiological, metabolite and proteomic analyses. Under stress conditions, tomato plants showed stunted growth, and elevated levels of proline, abscisic acid (ABA) and late embryogenesis abundant gene transcript. Proteomics revealed that water deficit deeply affects chloroplast protein repertoire (31 differentially represented components), mainly involving energy-related functional species. Following the rewatering cycle, physiological parameters and metabolite levels indicated a recovery of tomato plant functions, while proteomics revealed a still ongoing adjustment of the chloroplast protein repertoire, which was even wider than during the drought phase (54 components differentially represented). Changes in gene expression of candidate genes and accumulation of ABA suggested the activation under stress of a specific chloroplast-to-nucleus (retrograde) signaling pathway and interconnection with the ABA-dependent network. Our results give an original overview on the role of chloroplast as enviromental sensor by both coordinating the expression of nuclear-encoded plastid-localised proteins and mediating plant stress response. Although our data suggest the activation of a specific retrograde signaling pathway and interconnection with ABA signaling network in tomato, the involvement and fine regulation of such pathway need to be further investigated through the development and characterization of ad hoc designed plant mutants.

  6. Isolated plant mitochondria import chloroplast precursor proteins in vitro with the same efficiency as chloroplasts.

    PubMed

    Cleary, Suzanne P; Tan, Fui-Ching; Nakrieko, Kerry-Ann; Thompson, Simon J; Mullineaux, Philip M; Creissen, Gary P; von Stedingk, Erik; Glaser, Elzbieta; Smith, Alison G; Robinson, Colin

    2002-02-15

    Most chloroplast and mitochondrial proteins are synthesized with N-terminal presequences that direct their import into the appropriate organelle. In this report we have analyzed the specificity of standard in vitro assays for import into isolated pea chloroplasts and mitochondria. We find that chloroplast protein import is highly specific because mitochondrial proteins are not imported to any detectable levels. Surprisingly, however, pea mitochondria import a range of chloroplast protein precursors with the same efficiency as chloroplasts, including those of plastocyanin, the 33-kDa photosystem II protein, Hcf136, and coproporphyrinogen III oxidase. These import reactions are dependent on the Deltaphi across the inner mitochondrial membrane, and furthermore, marker enzyme assays and Western blotting studies exclude any import by contaminating chloroplasts in the preparation. The pea mitochondria specifically recognize information in the chloroplast-targeting presequences, because they also import a fusion comprising the presequence of coproporphyrinogen III oxidase linked to green fluorescent protein. However, the same construct is targeted exclusively into chloroplasts in vivo indicating that the in vitro mitochondrial import reactions are unphysiological, possibly because essential specificity factors are absent in these assays. Finally, we show that disruption of potential amphipathic helices in one presequence does not block import into pea mitochondria, indicating that other features are recognized.

  7. REDUCED CHLOROPLAST COVERAGE genes from Arabidopsis thaliana help to establish the size of the chloroplast compartment

    DOE PAGES

    Larkin, Robert M.; Stefano, Giovanni; Ruckle, Michael E.; ...

    2016-02-09

    Eukaryotic cells require mechanisms to establish the proportion of cellular volume devoted to particular organelles. These mechanisms are poorly understood. From a screen for plastid-to-nucleus signaling mutants in Arabidopsis thaliana, we cloned a mutant allele of a gene that encodes a protein of unknown function that is homologous to two other Arabidopsis genes of unknown function and Arabidopsis. In contrast to FRIENDLY, these three homologs of FRIENDLY are found only in photosynthetic organisms. Based on these data, we proposed that FRIENDLY expanded into a small gene family to help regulate the energy metabolism of cells that contain both mitochondria andmore » chloroplasts. Indeed, we found that knocking out these genes caused a number of chloroplast phenotypes, including a reduction in the proportion of cellular volume devoted to chloroplasts to 50% of wild type. Thus, we refer to these genes as REDUCED CHLOROPLAST COVERAGE (REC). The size of the chloroplast compartment was reduced most in rec1 mutants. The REC1 protein accumulated in the cytosol and the nucleus. REC1 was excluded from the nucleus when plants were treated with amitrole, which inhibits cell expansion and chloroplast function. Finally, we conclude that REC1 is an extraplastidic protein that helps to establish the size of the chloroplast compartment, and that signals derived from cell expansion or chloroplasts may regulate REC1.« less

  8. REDUCED CHLOROPLAST COVERAGE genes from Arabidopsis thaliana help to establish the size of the chloroplast compartment

    PubMed Central

    Larkin, Robert M.; Stefano, Giovanni; Ruckle, Michael E.; Stavoe, Andrea K.; Sinkler, Christopher A.; Brandizzi, Federica; Malmstrom, Carolyn M.; Osteryoung, Katherine W.

    2016-01-01

    Eukaryotic cells require mechanisms to establish the proportion of cellular volume devoted to particular organelles. These mechanisms are poorly understood. From a screen for plastid-to-nucleus signaling mutants in Arabidopsis thaliana, we cloned a mutant allele of a gene that encodes a protein of unknown function that is homologous to two other Arabidopsis genes of unknown function and to FRIENDLY, which was previously shown to promote the normal distribution of mitochondria in Arabidopsis. In contrast to FRIENDLY, these three homologs of FRIENDLY are found only in photosynthetic organisms. Based on these data, we proposed that FRIENDLY expanded into a small gene family to help regulate the energy metabolism of cells that contain both mitochondria and chloroplasts. Indeed, we found that knocking out these genes caused a number of chloroplast phenotypes, including a reduction in the proportion of cellular volume devoted to chloroplasts to 50% of wild type. Thus, we refer to these genes as REDUCED CHLOROPLAST COVERAGE (REC). The size of the chloroplast compartment was reduced most in rec1 mutants. The REC1 protein accumulated in the cytosol and the nucleus. REC1 was excluded from the nucleus when plants were treated with amitrole, which inhibits cell expansion and chloroplast function. We conclude that REC1 is an extraplastidic protein that helps to establish the size of the chloroplast compartment, and that signals derived from cell expansion or chloroplasts may regulate REC1. PMID:26862170

  9. REDUCED CHLOROPLAST COVERAGE genes from Arabidopsis thaliana help to establish the size of the chloroplast compartment.

    PubMed

    Larkin, Robert M; Stefano, Giovanni; Ruckle, Michael E; Stavoe, Andrea K; Sinkler, Christopher A; Brandizzi, Federica; Malmstrom, Carolyn M; Osteryoung, Katherine W

    2016-02-23

    Eukaryotic cells require mechanisms to establish the proportion of cellular volume devoted to particular organelles. These mechanisms are poorly understood. From a screen for plastid-to-nucleus signaling mutants in Arabidopsis thaliana, we cloned a mutant allele of a gene that encodes a protein of unknown function that is homologous to two other Arabidopsis genes of unknown function and to FRIENDLY, which was previously shown to promote the normal distribution of mitochondria in Arabidopsis. In contrast to FRIENDLY, these three homologs of FRIENDLY are found only in photosynthetic organisms. Based on these data, we proposed that FRIENDLY expanded into a small gene family to help regulate the energy metabolism of cells that contain both mitochondria and chloroplasts. Indeed, we found that knocking out these genes caused a number of chloroplast phenotypes, including a reduction in the proportion of cellular volume devoted to chloroplasts to 50% of wild type. Thus, we refer to these genes as REDUCED CHLOROPLAST COVERAGE (REC). The size of the chloroplast compartment was reduced most in rec1 mutants. The REC1 protein accumulated in the cytosol and the nucleus. REC1 was excluded from the nucleus when plants were treated with amitrole, which inhibits cell expansion and chloroplast function. We conclude that REC1 is an extraplastidic protein that helps to establish the size of the chloroplast compartment, and that signals derived from cell expansion or chloroplasts may regulate REC1.

  10. Strong genetic differentiation in the invasive annual grass Bromus tectorum across the Mojave-Great Basin ecological transition zone

    Treesearch

    Susan E. Meyer; Elizabeth A. Leger; Desiree R. Eldon; Craig E. Coleman

    2016-01-01

    Bromus tectorum, an inbreeding annual grass, is a dominant invader in sagebrush steppe habitat in North America. It is also common in warm and salt deserts, displaying a larger environmental tolerance than most native species. We tested the hypothesis that a suite of habitat-specific B. tectorum lineages dominates warm desert habitats. We sampled 30 B....

  11. Chloroplast genomes: diversity, evolution, and applications in genetic engineering

    DOE PAGES

    Daniell, Henry; Lin, Choun -Sea; Yu, Ming; ...

    2016-06-23

    Chloroplasts play a crucial role in sustaining life on earth. The availability of over 800 sequenced chloroplast genomes from a variety of land plants has enhanced our understanding of chloroplast biology, intracellular gene transfer, conservation, diversity, and the genetic basis by which chloroplast transgenes can be engineered to enhance plant agronomic traits or to produce high-value agricultural or biomedical products. In this review, we discuss the impact of chloroplast genome sequences on understanding the origins of economically important cultivated species and changes that have taken place during domestication. Here, we also discuss the potential biotechnological applications of chloroplast genomes.

  12. Three-Dimensional Visualization of the Tubular-Lamellar Transformation of the Internal Plastid Membrane Network during Runner Bean Chloroplast Biogenesis

    PubMed Central

    Suski, Szymon

    2016-01-01

    Chloroplast biogenesis is a complex process that is integrated with plant development, leading to fully differentiated and functionally mature plastids. In this work, we used electron tomography and confocal microscopy to reconstruct the process of structural membrane transformation during the etioplast-to-chloroplast transition in runner bean (Phaseolus coccineus). During chloroplast development, the regular tubular network of paracrystalline prolamellar bodies (PLBs) and the flattened porous membranes of prothylakoids develop into the chloroplast thylakoids. Three-dimensional reconstruction is required to provide us with a more complete understanding of this transformation. We provide spatial models of the bean chloroplast biogenesis that allow such reconstruction of the internal membranes of the developing chloroplast and visualize the transformation from the tubular arrangement to the linear system of parallel lamellae. We prove that the tubular structure of the PLB transforms directly to flat slats, without dispersion to vesicles. We demonstrate that the grana/stroma thylakoid connections have a helical character starting from the early stages of appressed membrane formation. Moreover, we point out the importance of particular chlorophyll-protein complex components in the membrane stacking during the biogenesis. The main stages of chloroplast internal membrane biogenesis are presented in a movie that shows the time development of the chloroplast biogenesis as a dynamic model of this process. PMID:27002023

  13. Genome Sequences of Populus tremula Chloroplast and Mitochondrion: Implications for Holistic Poplar Breeding.

    PubMed

    Kersten, Birgit; Faivre Rampant, Patricia; Mader, Malte; Le Paslier, Marie-Christine; Bounon, Rémi; Berard, Aurélie; Vettori, Cristina; Schroeder, Hilke; Leplé, Jean-Charles; Fladung, Matthias

    2016-01-01

    Complete Populus genome sequences are available for the nucleus (P. trichocarpa; section Tacamahaca) and for chloroplasts (seven species), but not for mitochondria. Here, we provide the complete genome sequences of the chloroplast and the mitochondrion for the clones P. tremula W52 and P. tremula x P. alba 717-1B4 (section Populus). The organization of the chloroplast genomes of both Populus clones is described. A phylogenetic tree constructed from all available complete chloroplast DNA sequences of Populus was not congruent with the assignment of the related species to different Populus sections. In total, 3,024 variable nucleotide positions were identified among all compared Populus chloroplast DNA sequences. The 5-prime part of the LSC from trnH to atpA showed the highest frequency of variations. The variable positions included 163 positions with SNPs allowing for differentiating the two clones with P. tremula chloroplast genomes (W52, 717-1B4) from the other seven Populus individuals. These potential P. tremula-specific SNPs were displayed as a whole-plastome barcode on the P. tremula W52 chloroplast DNA sequence. Three of these SNPs and one InDel in the trnH-psbA linker were successfully validated by Sanger sequencing in an extended set of Populus individuals. The complete mitochondrial genome sequence of P. tremula is the first in the family of Salicaceae. The mitochondrial genomes of the two clones are 783,442 bp (W52) and 783,513 bp (717-1B4) in size, structurally very similar and organized as single circles. DNA sequence regions with high similarity to the W52 chloroplast sequence account for about 2% of the W52 mitochondrial genome. The mean SNP frequency was found to be nearly six fold higher in the chloroplast than in the mitochondrial genome when comparing 717-1B4 with W52. The availability of the genomic information of all three DNA-containing cell organelles will allow a holistic approach in poplar molecular breeding in the future.

  14. Genome Sequences of Populus tremula Chloroplast and Mitochondrion: Implications for Holistic Poplar Breeding

    PubMed Central

    Mader, Malte; Le Paslier, Marie-Christine; Bounon, Rémi; Berard, Aurélie; Vettori, Cristina; Schroeder, Hilke; Leplé, Jean-Charles; Fladung, Matthias

    2016-01-01

    Complete Populus genome sequences are available for the nucleus (P. trichocarpa; section Tacamahaca) and for chloroplasts (seven species), but not for mitochondria. Here, we provide the complete genome sequences of the chloroplast and the mitochondrion for the clones P. tremula W52 and P. tremula x P. alba 717-1B4 (section Populus). The organization of the chloroplast genomes of both Populus clones is described. A phylogenetic tree constructed from all available complete chloroplast DNA sequences of Populus was not congruent with the assignment of the related species to different Populus sections. In total, 3,024 variable nucleotide positions were identified among all compared Populus chloroplast DNA sequences. The 5-prime part of the LSC from trnH to atpA showed the highest frequency of variations. The variable positions included 163 positions with SNPs allowing for differentiating the two clones with P. tremula chloroplast genomes (W52, 717-1B4) from the other seven Populus individuals. These potential P. tremula-specific SNPs were displayed as a whole-plastome barcode on the P. tremula W52 chloroplast DNA sequence. Three of these SNPs and one InDel in the trnH-psbA linker were successfully validated by Sanger sequencing in an extended set of Populus individuals. The complete mitochondrial genome sequence of P. tremula is the first in the family of Salicaceae. The mitochondrial genomes of the two clones are 783,442 bp (W52) and 783,513 bp (717-1B4) in size, structurally very similar and organized as single circles. DNA sequence regions with high similarity to the W52 chloroplast sequence account for about 2% of the W52 mitochondrial genome. The mean SNP frequency was found to be nearly six fold higher in the chloroplast than in the mitochondrial genome when comparing 717-1B4 with W52. The availability of the genomic information of all three DNA-containing cell organelles will allow a holistic approach in poplar molecular breeding in the future. PMID:26800039

  15. Chloroplast anchoring: its implications for the regulation of intracellular chloroplast distribution.

    PubMed

    Takagi, Shingo; Takamatsu, Hideyasu; Sakurai-Ozato, Nami

    2009-01-01

    The intracellular distribution of organelles plays a pivotal role in the maintenance and adaptation of a wide spectrum of cellular activities in plants. Chloroplasts are a special type of organelle able to photosynthesize, capturing light energy to fix atmospheric CO2. Consequently, the intracellular positioning of chloroplasts is crucial for plant growth and development. Knowledge of the photoreceptors and cellular apparatus responsible for chloroplast movement has gradually accumulated over time, yet recent advances have allowed improved understanding. In this article, several aspects of research progress into the mechanisms for maintaining the specific intracellular distribution patterns of chloroplasts, namely, chloroplast anchoring, are summarized, together with a brief consideration of the future prospects of this subject. Our discussion covers developmental, physiological, ecophysiological, and recent cell biological research areas.

  16. Evolutionary development of redox regulation in chloroplasts.

    PubMed

    Balsera, Monica; Uberegui, Estefania; Schürmann, Peter; Buchanan, Bob B

    2014-09-20

    The post-translational modification of thiol groups stands out as a key strategy that cells employ for metabolic regulation and adaptation to changing environmental conditions. Nowhere is this more evident than in chloroplasts-the O2-evolving photosynthetic organelles of plant cells that are fitted with multiple redox systems, including the thioredoxin (Trx) family of oxidoreductases functional in the reversible modification of regulatory thiols of proteins in all types of cells. The best understood member of this family in chloroplasts is the ferredoxin-linked thioredoxin system (FTS) by which proteins are modified via light-dependent disulfide/dithiol (S-S/2SH) transitions. Discovered in the reductive activation of enzymes of the Calvin-Benson cycle in illuminated chloroplast preparations, recent studies have extended the role of the FTS far beyond its original boundaries to include a spectrum of cellular processes. Together with the NADP-linked thioredoxin reductase C-type (NTRC) and glutathione/glutaredoxin systems, the FTS also plays a central role in the response of chloroplasts to different types of stress. The comparisons of redox regulatory networks functional in chloroplasts of land plants with those of cyanobacteria-prokaryotes considered to be the ancestors of chloroplasts-and different types of algae summarized in this review have provided new insight into the evolutionary development of redox regulation, starting with the simplest O2-evolving organisms. The evolutionary appearance, mode of action, and specificity of the redox regulatory systems functional in chloroplasts, as well as the types of redox modification operating under diverse environmental conditions stand out as areas for future study.

  17. Cryoprotection by Glucose, Sucrose, and Raffinose to Chloroplast Thylakoids 1

    PubMed Central

    Lineberger, R. Daniel; Steponkus, Peter L.

    1980-01-01

    Differential cryoprotection is afforded to chloroplast thylakoids against freeze-induced uncoupling of cyclic photophosphorylation by equimolar concentrations of glucose, sucrose, and raffinose. This differential protective effect appears to be due to nonideal activity-concentration profiles exhibited by the sugars during freezing. When cryoprotection is analyzed as a function of the mole fraction of NaCl to which the membranes are exposed during freezing, the pattern of protection to cyclic photophosphorylation and its component reactions is not dependent upon the chemical identity of the protective solute. Cryoprotective efficiency of glucose, sucrose, and raffinose can be accounted for by proposing an activity dependent alteration in the freezing environment rather than specific solute-membrane interactions. PMID:16661177

  18. Chloroplasts Are Central Players in Sugar-Induced Leaf Growth.

    PubMed

    Van Dingenen, Judith; De Milde, Liesbeth; Vermeersch, Mattias; Maleux, Katrien; De Rycke, Riet; De Bruyne, Michiel; Storme, Véronique; Gonzalez, Nathalie; Dhondt, Stijn; Inzé, Dirk

    2016-05-01

    Leaves are the plant's powerhouses, providing energy for all organs through sugar production during photosynthesis. However, sugars serve not only as a metabolic energy source for sink tissues but also as signaling molecules, affecting gene expression through conserved signaling pathways to regulate plant growth and development. Here, we describe an in vitro experimental assay, allowing one to alter the sucrose (Suc) availability during early Arabidopsis (Arabidopsis thaliana) leaf development, with the aim to identify the affected cellular and molecular processes. The transfer of seedlings to Suc-containing medium showed a profound effect on leaf growth by stimulating cell proliferation and postponing the transition to cell expansion. Furthermore, rapidly after transfer to Suc, mesophyll cells contained fewer and smaller plastids, which are irregular in shape and contain fewer starch granules compared with control mesophyll cells. Short-term transcriptional responses after transfer to Suc revealed the repression of well-known sugar-responsive genes and multiple genes encoded by the plastid, on the one hand, and up-regulation of a GLUCOSE-6-PHOSPHATE TRANSPORTER (GPT2), on the other hand. Mutant gpt2 seedlings showed no stimulation of cell proliferation and no repression of chloroplast-encoded transcripts when transferred to Suc, suggesting that GPT2 plays a critical role in the Suc-mediated effects on early leaf growth. Our findings, therefore, suggest that induction of GPT2 expression by Suc increases the import of glucose-6-phosphate into the plastids that would repress chloroplast-encoded transcripts, restricting chloroplast differentiation. Retrograde signaling from the plastids would then delay the transition to cell expansion and stimulate cell proliferation. © 2016 American Society of Plant Biologists. All Rights Reserved.

  19. Defining the Core Proteome of the Chloroplast Envelope Membranes

    PubMed Central

    Simm, Stefan; Papasotiriou, Dimitrios G.; Ibrahim, Mohamed; Leisegang, Matthias S.; Müller, Bernd; Schorge, Tobias; Karas, Michael; Mirus, Oliver; Sommer, Maik S.; Schleiff, Enrico

    2013-01-01

    High-throughput protein localization studies require multiple strategies. Mass spectrometric analysis of defined cellular fractions is one of the complementary approaches to a diverse array of cell biological methods. In recent years, the protein content of different cellular (sub-)compartments was approached. Despite of all the efforts made, the analysis of membrane fractions remains difficult, in that the dissection of the proteomes of the envelope membranes of chloroplasts or mitochondria is often not reliable because sample purity is not always warranted. Moreover, proteomic studies are often restricted to single (model) species, and therefore limited in respect to differential individual evolution. In this study we analyzed the chloroplast envelope proteomes of different plant species, namely, the individual proteomes of inner and outer envelope (OE) membrane of Pisum sativum and the mixed envelope proteomes of Arabidopsis thaliana and Medicago sativa. The analysis of all three species yielded 341 identified proteins in total, 247 of them being unique. 39 proteins were genuine envelope proteins found in at least two species. Based on this and previous envelope studies we defined the core envelope proteome of chloroplasts. Comparing the general overlap of the available six independent studies (including ours) revealed only a number of 27 envelope proteins. Depending on the stringency of applied selection criteria we found 231 envelope proteins, while less stringent criteria increases this number to 649 putative envelope proteins. Based on the latter we provide a map of the outer and inner envelope core proteome, which includes many yet uncharacterized proteins predicted to be involved in transport, signaling, and response. Furthermore, a foundation for the functional characterization of yet unidentified functions of the inner and OE for further analyses is provided. PMID:23390424

  20. Carbohydrate breakdown by chloroplasts of Pisum sativum.

    PubMed

    Stitt, M; Rees, T A

    1980-01-17

    1. The aims of this work were to discover the pathways of starch breakdown and carbohydrate metabolism in intact isolated chloroplasts from shoots of Pisum sativum. 2. 14C from starch, labelled by supplying [14C]glucose to chloroplasts, appeared, during starch breakdown, in CO2, maltose and the fraction of the acidic compounds that contained 3-phosphoglycerate and sugar phosphates. 3. When intact chloroplasts were incubated in the dark, 3-phosphoglycerate, triose phosphates and, to a lesser extent, hexose 6-phosphates accumulated in the medium at rates comparable to those of starch breakdown in leaves. This accumulation was dependent upon orthophosphate. 4. The patterns of 14CO2 production from specifically labelled [14C]glucose supplied to isolated chloroplasts were those expected of the oxidative pentose phosphate pathway with extensive recycling, and glycolysis. The respone of this pattern to lack of orthophosphate, addition of unlabelled intermediates, and 2-phosphoglycollate confirmed this view. 5. Starch breakdown in pea chloroplasts is held to be dominantly phosphorolytic with the products being metabolized via the oxidative pentose phosphate pathway and glycolysis to 3-phosphoglycerate, triose phosphates and CO2 that are exported to the cytoplasm.

  1. Heme content and breakdown in developing chloroplasts

    SciTech Connect

    Thomas, J.; Weinstein, J.D. )

    1990-05-01

    Heme regulates tetrapyrrole biosynthesis in plants by inhibition of {delta}-aminolevulinic acid (ALA) synthesis, product inhibition of heme synthesis, and possibly other mechanisms. Plastid heme levels may be modulated by heme synthesis, breakdown and/or efflux. Heme breakdown may be catalyzed by a chloroplast localized heme oxygenase. Chloroplasts isolated from greening cucumber cotyledons were incubated in the presence or absence of various components thought to modulate heme breakdown. Following the incubations, the chloroplasts were broken (freeze-thaw) and then supplemented with horseradish peroxidase apoenzyme. The reconstituted peroxidase activity was used to determine the amount of free heme remaining (Thomas Weinstein (1989) Plant Physiol. 89S: 74). Chloroplasts, freshly isolated from seedlings greened for 16 hours, contained approximately 37 pmol heme/mg protein. When chloroplasts were incubated with 5 mM NADPH for 30 min, the endogenous heme dropped to unmeasurable levels. Exogenous heme was also broken down when NADPH was included in the incubation. Heme levels could be increased by the inclusion of 50 {mu}M ALA and/or p-hydroxymercuribenzoate. The increase due to exogenous ALA was blocked by levulinic acid, an inhibitor of ALA utilization. NADPH-dependent heme breakdown acid was inhibited by p-hydroxymercuribenzoate.

  2. Isolation and Suborganellar Fractionation of Arabidopsis Chloroplasts.

    PubMed

    Flores-Pérez, Úrsula; Jarvis, Paul

    2017-01-01

    Chloroplasts are structurally complex organelles containing ~2000-3000 proteins. They are delimited by a double membrane system or envelope, have an inner aqueous compartment called the stroma, and possess a second internal membrane system called the thylakoids. Thus, determining the suborganellar location of a chloroplast protein is vital to understanding or verifying its function. One way in which protein localization can be addressed is through fractionation. Here we present two rapid and simple methods that may be applied sequentially on the same day: (a) The isolation of intact chloroplasts from Arabidopsis thaliana plants that may be used directly (e.g., for functional studies such as protein import analysis), or for further processing as follows; (b) separation of isolated chloroplasts into three suborganellar fractions (envelope membranes, a soluble fraction containing stromal proteins, and the thylakoids). These methods are routinely used in our laboratory, and they provide a good yield of isolated chloroplasts and suborganellar fractions that can be used for various downstream applications.

  3. Glycolate transporter of the pea chloroplast envelope

    SciTech Connect

    Howitz, K.T.

    1985-01-01

    The discovery of a glycolate transporter in the pea (Pisum sativum) chloroplast envelope is described. Several novel silicone oil centrifugation methods were developed to resolve the initial rate kinetics of (/sup 14/C)glycolate transport by isolated, intact pea chloroplasts. Chloroplast glycolate transport was found to be carrier mediated. Transport rates saturated with increasing glycolate concentration. N-Ethylmaleimide (NEM) pretreatment of chloroplasts inhibited transport, an inhibition prevented by glycolate. Glycolate distributed across the envelope in a way which equalized stromal and medium glycolic acid concentrations, limiting possible transport mechanisms to facilitated glycolic acid diffusion, proton symport or hydroxyl antiport. The effects of stomal and medium pH's on the K/sub m/ and V/sub max/ fit the predictions of mobile carrier kinetic models of hydroxyl antiport or proton symport (H/sup +/ binds first). The carrier mediated transport was fast enough to be consistent with in vivo rates of photorespiration. The 2-hydroxymonocarboxylates, glycerate, lactate and glyoxylate are competitive inhibitors of chloroplast glycolate uptake. Glyoxylate, D-lactate and D-glycerate cause glycolate counterflow, indicating that they are also substrates of the glycolate carrier. This finding was confirmed for D-glycerate by studies on glycolate effects on (1-/sup 14/C)D-glycerate transport.

  4. Vectorial photocurrents and photoconductivity in metalized chloroplasts

    SciTech Connect

    Greenbaum, E. )

    1990-08-09

    A novel photobiophysical phenomenon was observed in isolated spinach chloroplasts that were metalized by precipitating colloidal platinum onto the surface of the thylakoid membranes. A two-point irradiation and detection system was constructed in which a continuous-beam helium-neon laser ({lambda} = 632.8 nm) was used to irradiate the platinized chloroplasts at varying perpendicular distances (Figure 1) from a single linear platinum electrode in pressure contact with the platinized chloroplasts. No external voltage bias was applied to the system. The key objective of the experiments reported in this report was to measure the relative photoconductivity of the chloroplast-metal composite matrix. Unlike conventional photosynthetic electrochemical cells, in which irradiated chloroplasts are in close proximity to an electrode or linked to the electrode by an electrode-active mediator, the flow of photocurrent was through the biocomposite material. A sustained steady-state vectorial flow of current in the plane of the entrapped composite from the point of laser irradiation to the wire electrode was measured.

  5. Proteomic Insight into the Response of Arabidopsis Chloroplasts to Darkness

    PubMed Central

    Wang, Jing; Yu, Qingbo; Xiong, Haibo; Wang, Jun; Chen, Sixue; Yang, Zhongnan; Dai, Shaojun

    2016-01-01

    Chloroplast function in photosynthesis is essential for plant growth and development. It is well-known that chloroplasts respond to various light conditions. However, it remains poorly understood about how chloroplasts respond to darkness. In this study, we found 81 darkness-responsive proteins in Arabidopsis chloroplasts under 8 h darkness treatment. Most of the proteins are nucleus-encoded, indicating that chloroplast darkness response is closely regulated by the nucleus. Among them, 17 ribosome proteins were obviously reduced after darkness treatment. The protein expressional patterns and physiological changes revealed the mechanisms in chloroplasts in response to darkness, e.g., (1) inhibition of photosystem II resulted in preferential cyclic electron flow around PSI; (2) promotion of starch degradation; (3) inhibition of chloroplastic translation; and (4) regulation by redox and jasmonate signaling. The results have improved our understanding of molecular regulatory mechanisms in chloroplasts under darkness. PMID:27137770

  6. Roles of actin cytoskeleton for regulation of chloroplast anchoring.

    PubMed

    Sakai, Yuuki; Takagi, Shingo

    2017-08-22

    Chloroplasts are known to maintain specific intracellular distribution patterns under specific environmental conditions, enabling the optimal performance of photosynthesis. To this end, chloroplasts are anchored in the cortical cytoplasm. In leaf epidermal cells of aquatic monocot Vallisneria, we recently demonstrated that the anchored chloroplasts are rapidly de-anchored upon irradiation with high-intensity blue light and that the process is probably mediated by the blue-light receptor phototropins. Chloroplast de-anchoring is a necessary step rendering the previously anchored chloroplasts mobile to allow their migration. In this article, based on the results obtained in Vallisneria together with those in other plant species, we briefly discussed possible modes of regulation of chloroplast anchoring and de-anchoring by actin cytoskeleton. The topics include roles of photoreceptor systems, actin-filament-dependent and -independent chloroplast anchoring, and independence of chloroplast de-anchoring from actomyosin and microtubule systems.

  7. Mergers and acquisitions: malaria and the great chloroplast heist.

    PubMed

    McFadden, G I

    2000-01-01

    The origin of the relict chloroplast recently identified in malarial parasites has been mysterious. Several new papers suggest that the parasites obtained their chloroplasts in an ancient endosymbiotic event that also created some major algal groups.

  8. Mergers and acquisitions: malaria and the great chloroplast heist

    PubMed Central

    McFadden, Geoffrey I

    2000-01-01

    The origin of the relict chloroplast recently identified in malarial parasites has been mysterious. Several new papers suggest that the parasites obtained their chloroplasts in an ancient endosymbiotic event that also created some major algal groups. PMID:11178253

  9. Proteomic Insight into the Response of Arabidopsis Chloroplasts to Darkness.

    PubMed

    Wang, Jing; Yu, Qingbo; Xiong, Haibo; Wang, Jun; Chen, Sixue; Yang, Zhongnan; Dai, Shaojun

    2016-01-01

    Chloroplast function in photosynthesis is essential for plant growth and development. It is well-known that chloroplasts respond to various light conditions. However, it remains poorly understood about how chloroplasts respond to darkness. In this study, we found 81 darkness-responsive proteins in Arabidopsis chloroplasts under 8 h darkness treatment. Most of the proteins are nucleus-encoded, indicating that chloroplast darkness response is closely regulated by the nucleus. Among them, 17 ribosome proteins were obviously reduced after darkness treatment. The protein expressional patterns and physiological changes revealed the mechanisms in chloroplasts in response to darkness, e.g., (1) inhibition of photosystem II resulted in preferential cyclic electron flow around PSI; (2) promotion of starch degradation; (3) inhibition of chloroplastic translation; and (4) regulation by redox and jasmonate signaling. The results have improved our understanding of molecular regulatory mechanisms in chloroplasts under darkness.

  10. Conjugated Polymer Nanoparticles to Augment Photosynthesis of Chloroplasts.

    PubMed

    Wang, Yunxia; Li, Shengliang; Liu, Libing; Lv, Fengting; Wang, Shu

    2017-05-02

    By coating chloroplasts with conjugated polymer nanoparticles (CPNs), a new bio-optical hybrid photosynthesis system (chloroplast/CPNs) is developed. Since CPNs possess unique light harvesting ability, including the ultraviolet part that chloroplasts absorb less, chloroplast/CPN complexes can capture broader range of light to accelerate the electron transport rates in photosystem II (PS II), the critical protein complex in chloroplasts, and augment photosynthesis beyond natural chloroplasts. The degree of spectral overlay between emission of CPNs and absorption of chloroplasts is critical for the enhanced photosynthesis. This work exhibits good potential to explore new and facile nanoengineering strategy for reforming chloroplast with light-harvesting nanomaterials to enhance solar energy conversion. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Arabidopsis RUGOSA2 encodes an mTERF family member required for mitochondrion, chloroplast and leaf development.

    PubMed

    Quesada, Víctor; Sarmiento-Mañús, Raquel; González-Bayón, Rebeca; Hricová, Andrea; Pérez-Marcos, Rubén; Graciá-Martínez, Eva; Medina-Ruiz, Laura; Leyva-Díaz, Eduardo; Ponce, María Rosa; Micol, José Luis

    2011-11-01

    Little is known about the mechanisms that control transcription of the mitochondrial and chloroplastic genomes, and their interplay within plant cells. Here, we describe the positional cloning of the Arabidopsis RUG2 gene, which encodes a protein that is dual-targeted to mitochondria and chloroplasts, and is homologous with the metazoan mitochondrial transcription termination factors (mTERFs). In the loss-of-function rug2 mutants, most organs were pale and showed reduced growth, and the leaves exhibited both green and pale sectors, with the latter containing sparsely packed mesophyll cells. Chloroplast and mitochondrion development were strongly perturbed in the rug2-1 mutant, particularly in pale leaf sectors, in which chloroplasts were abnormally shaped and reduced in number, thereby impairing photoautotrophic growth. As expected from the pleiotropic phenotypes caused by its loss-of-function alleles, the RUG2 gene was ubiquitously expressed. In a microarray analysis of the mitochondrial and chloroplastic genomes, 56 genes were differentially expressed between rug2-1 and the wild type: most mitochondrial genes were downregulated, whereas the majority of the chloroplastic genes were upregulated. Quantitative RT-PCR analyses showed that the rug2-1 mutation specifically increases expression of the RpoTp nuclear gene, which encodes chloroplastic RNA polymerase. Therefore, the RUG2 nuclear gene seems to be crucial for the maintenance of the correct levels of transcripts in the mitochondria and chloroplasts, which is essential for optimized functions of these organelles and proper plant development. Our results highlight the complexity of the functional interaction between these two organelles and the nucleus. © 2011 The Authors. The Plant Journal © 2011 Blackwell Publishing Ltd.

  12. Raffinose in chloroplasts is synthesized in the cytosol and transported across the chloroplast envelope.

    PubMed

    Schneider, Thomas; Keller, Felix

    2009-12-01

    In chloroplasts, several water-soluble carbohydrates have been suggested to act as stress protectants. The trisaccharide raffinose (alpha-1,6-galactosyl sucrose) is such a carbohydrate but has received little attention. We here demonstrate by compartmentation analysis of leaf mesophyll protoplasts that raffinose is clearly (to about 20%) present in chloroplasts of cold-treated common bugle (Ajuga reptans L.), spinach (Spinacia oleracea L.) and Arabidopsis [Arabidopsis thaliana (L.) Heynh.] plants. The two dedicated enzymes needed for raffinose synthesis, galactinol synthase and raffinose synthase, were found to be extra-chloroplastic (probably cytosolic) in location, suggesting that the chloroplast envelope contains a raffinose transporter. Uptake experiments with isolated Ajuga and Arabidopsis chloroplasts clearly demonstrated that raffinose is indeed transported across the chloroplast envelope by a raffinose transporter, probably actively. Raffinose uptake into Ajuga chloroplasts was a saturable process with apparent K(m) and v(max) values of 27.8 mM and 3.3 micromol mg(-1) Chl min(-1), respectively.

  13. A Putative Chloroplast Thylakoid Metalloprotease VIRESCENT3 Regulates Chloroplast Development in Arabidopsis thaliana*

    PubMed Central

    Qi, Yafei; Liu, Xiayan; Liang, Shuang; Wang, Rui; Li, Yuanfeng; Zhao, Jun; Shao, Jingxia; An, Lijun; Yu, Fei

    2016-01-01

    The chloroplast is the site of photosynthesis and many other essential plant metabolic processes, and chloroplast development is an integral part of plant growth and development. Mutants defective in chloroplast development can display various color phenotypes including the intriguing virescence phenotype, which shows yellow/white coloration at the leaf base and greening toward the leaf tip. Through large scale genetic screens, we identified a series of new virescent mutants including virescent3-1 (vir3-1), vir4-1, and vir5-1 in Arabidopsis thaliana. We showed that VIR3 encodes a putative chloroplast metalloprotease by map-based cloning. Through site-directed mutagenesis, we showed that the conserved histidine 235 residue in the zinc binding motif HEAGH of VIR3 is indispensable for VIR3 accumulation in the chloroplast. The chloroplast localization of VIR3 was confirmed by the transient expression of VIR3-GFP in leaf protoplasts. Furthermore, taking advantage of transgenic lines expressing VIR3-FLAG, we demonstrated that VIR3 is an intrinsic thylakoid membrane protein that mainly resides in the stromal lamellae. Moreover, topology analysis using transgenic lines expressing a dual epitope-tagged VIR3 indicated that both the N and C termini of VIR3 are located in the stroma, and the catalytic domain of VIR3 is probably facing the stroma. Blue native gel analysis indicated that VIR3 is likely present as a monomer or part of a small complex in the thylakoid membrane. This work not only implicates VIR3 as a new factor involved in early chloroplast development but also provides more insight into the roles of chloroplast proteases in chloroplast biogenesis. PMID:26702056

  14. Analyses of Charophyte Chloroplast Genomes Help Characterize the Ancestral Chloroplast Genome of Land Plants

    PubMed Central

    Civáň, Peter; Foster, Peter G.; Embley, Martin T.; Séneca, Ana; Cox, Cymon J.

    2014-01-01

    Despite the significance of the relationships between embryophytes and their charophyte algal ancestors in deciphering the origin and evolutionary success of land plants, few chloroplast genomes of the charophyte algae have been reconstructed to date. Here, we present new data for three chloroplast genomes of the freshwater charophytes Klebsormidium flaccidum (Klebsormidiophyceae), Mesotaenium endlicherianum (Zygnematophyceae), and Roya anglica (Zygnematophyceae). The chloroplast genome of Klebsormidium has a quadripartite organization with exceptionally large inverted repeat (IR) regions and, uniquely among streptophytes, has lost the rrn5 and rrn4.5 genes from the ribosomal RNA (rRNA) gene cluster operon. The chloroplast genome of Roya differs from other zygnematophycean chloroplasts, including the newly sequenced Mesotaenium, by having a quadripartite structure that is typical of other streptophytes. On the basis of the improbability of the novel gain of IR regions, we infer that the quadripartite structure has likely been lost independently in at least three zygnematophycean lineages, although the absence of the usual rRNA operonic synteny in the IR regions of Roya may indicate their de novo origin. Significantly, all zygnematophycean chloroplast genomes have undergone substantial genomic rearrangement, which may be the result of ancient retroelement activity evidenced by the presence of integrase-like and reverse transcriptase-like elements in the Roya chloroplast genome. Our results corroborate the close phylogenetic relationship between Zygnematophyceae and land plants and identify 89 protein-coding genes and 22 introns present in the chloroplast genome at the time of the evolutionary transition of plants to land, all of which can be found in the chloroplast genomes of extant charophytes. PMID:24682153

  15. A Putative Chloroplast Thylakoid Metalloprotease VIRESCENT3 Regulates Chloroplast Development in Arabidopsis thaliana.

    PubMed

    Qi, Yafei; Liu, Xiayan; Liang, Shuang; Wang, Rui; Li, Yuanfeng; Zhao, Jun; Shao, Jingxia; An, Lijun; Yu, Fei

    2016-02-12

    The chloroplast is the site of photosynthesis and many other essential plant metabolic processes, and chloroplast development is an integral part of plant growth and development. Mutants defective in chloroplast development can display various color phenotypes including the intriguing virescence phenotype, which shows yellow/white coloration at the leaf base and greening toward the leaf tip. Through large scale genetic screens, we identified a series of new virescent mutants including virescent3-1 (vir3-1), vir4-1, and vir5-1 in Arabidopsis thaliana. We showed that VIR3 encodes a putative chloroplast metalloprotease by map-based cloning. Through site-directed mutagenesis, we showed that the conserved histidine 235 residue in the zinc binding motif HEAGH of VIR3 is indispensable for VIR3 accumulation in the chloroplast. The chloroplast localization of VIR3 was confirmed by the transient expression of VIR3-GFP in leaf protoplasts. Furthermore, taking advantage of transgenic lines expressing VIR3-FLAG, we demonstrated that VIR3 is an intrinsic thylakoid membrane protein that mainly resides in the stromal lamellae. Moreover, topology analysis using transgenic lines expressing a dual epitope-tagged VIR3 indicated that both the N and C termini of VIR3 are located in the stroma, and the catalytic domain of VIR3 is probably facing the stroma. Blue native gel analysis indicated that VIR3 is likely present as a monomer or part of a small complex in the thylakoid membrane. This work not only implicates VIR3 as a new factor involved in early chloroplast development but also provides more insight into the roles of chloroplast proteases in chloroplast biogenesis. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  16. Analyses of charophyte chloroplast genomes help characterize the ancestral chloroplast genome of land plants.

    PubMed

    Civaň, Peter; Foster, Peter G; Embley, Martin T; Séneca, Ana; Cox, Cymon J

    2014-04-01

    Despite the significance of the relationships between embryophytes and their charophyte algal ancestors in deciphering the origin and evolutionary success of land plants, few chloroplast genomes of the charophyte algae have been reconstructed to date. Here, we present new data for three chloroplast genomes of the freshwater charophytes Klebsormidium flaccidum (Klebsormidiophyceae), Mesotaenium endlicherianum (Zygnematophyceae), and Roya anglica (Zygnematophyceae). The chloroplast genome of Klebsormidium has a quadripartite organization with exceptionally large inverted repeat (IR) regions and, uniquely among streptophytes, has lost the rrn5 and rrn4.5 genes from the ribosomal RNA (rRNA) gene cluster operon. The chloroplast genome of Roya differs from other zygnematophycean chloroplasts, including the newly sequenced Mesotaenium, by having a quadripartite structure that is typical of other streptophytes. On the basis of the improbability of the novel gain of IR regions, we infer that the quadripartite structure has likely been lost independently in at least three zygnematophycean lineages, although the absence of the usual rRNA operonic synteny in the IR regions of Roya may indicate their de novo origin. Significantly, all zygnematophycean chloroplast genomes have undergone substantial genomic rearrangement, which may be the result of ancient retroelement activity evidenced by the presence of integrase-like and reverse transcriptase-like elements in the Roya chloroplast genome. Our results corroborate the close phylogenetic relationship between Zygnematophyceae and land plants and identify 89 protein-coding genes and 22 introns present in the chloroplast genome at the time of the evolutionary transition of plants to land, all of which can be found in the chloroplast genomes of extant charophytes.

  17. Protein methylation reactions in intact pea chloroplasts

    SciTech Connect

    Niemi, K.J. )

    1989-04-01

    Post-translational protein methylation was investigated in Pisum sativum chloroplasts. Intact pea chloroplasts were incubated with ({sup 3}H-methyl)-S-adenosylmethionine under various conditions. The chloroplasts were then separated into stromal and thylakoid fractions and analyzed for radioactivity transferred to protein. Light enhanced the magnitude of labeling in both fractions. One thylakoid polypeptide with an apparent molecular mass of 43 kDa was labeled only in the light. Several other thylakoid and stromal proteins were labeled in both light and dark-labeling conditions. Both base-labile methylation, carboxy-methylesters and base-stable groups, N-methylations were found. Further characterization of the methyl-transfer reactions will be presented.

  18. The chloroplast genome exists in multimeric forms

    SciTech Connect

    Deng, Xingwang; Wing, R.A.; Gruissem, W. )

    1989-06-01

    Chloroplast DNA conformation was analyzed by pulse-field gel electrophoresis. The authors found that spinach leaf chloroplast DNA molecules exist in at least four distinct forms with the apparent molecular weights of monomer, dimer, trimer, and tetramer. Two-dimensional gel analysis of DNA after UV nicking and in the presence of ethidium bromide indicates that they are not isomers that differ in superhelical density. DNA gyrase decatenation analysis demonstrates that the majority of the DNA molecules are oligomers rather than catenanes. The relative amounts of monomer, dimer, trimer, and tetramer forms, quantitated by molecular hybridization, are 1, 1/3, 1/9, and 1/27, respectively, and do not change during leaf maturation. The possible mechanisms of chloroplast DNA oligomer formation are discussed.

  19. Engineered Chloroplast Genome just got Smarter

    PubMed Central

    Jin, Shuangxia; Daniell, Henry

    2015-01-01

    Chloroplasts are known to sustain life on earth by providing food, fuel and oxygen through the process of photosynthesis. However, the chloroplast genome has also been smartly engineered to confer valuable agronomic traits and/or serve as bioreactors for production of industrial enzymes, biopharmaceuticals, bio-products or vaccines. The recent breakthrough in hyper-expression of biopharmaceuticals in edible leaves has facilitated the advancement to clinical studies by major pharmaceutical companies. This review critically evaluates progress in developing new tools to enhance or simplify expression of targeted genes in chloroplasts. These tools hold the promise to further the development of novel fuels and products, enhance the photosynthetic process, and increase our understanding of retrograde signaling and cellular processes. PMID:26440432

  20. Application of a simplified method of chloroplast enrichment to small amounts of tissue for chloroplast genome sequencing.

    PubMed

    Sakaguchi, Shota; Ueno, Saneyoshi; Tsumura, Yoshihiko; Setoguchi, Hiroaki; Ito, Motomi; Hattori, Chie; Nozoe, Shogo; Takahashi, Daiki; Nakamasu, Riku; Sakagami, Taishi; Lannuzel, Guillaume; Fogliani, Bruno; Wulff, Adrien S; L'Huillier, Laurent; Isagi, Yuji

    2017-05-01

    High-throughput sequencing of genomic DNA can recover complete chloroplast genome sequences, but the sequence data are usually dominated by sequences from nuclear/mitochondrial genomes. To overcome this deficiency, a simple enrichment method for chloroplast DNA from small amounts of plant tissue was tested for eight plant species including a gymnosperm and various angiosperms. Chloroplasts were enriched using a high-salt isolation buffer without any step gradient procedures, and enriched chloroplast DNA was sequenced by multiplexed high-throughput sequencing. Using this simple method, significant enrichment of chloroplast DNA-derived reads was attained, allowing deep sequencing of chloroplast genomes. As an example, the chloroplast genome of the conifer Callitris sulcata was assembled, from which polymorphic microsatellite loci were isolated successfully. This chloroplast enrichment method from small amounts of plant tissue will be particularly useful for studies that use sequencers with relatively small throughput and that cannot use large amounts of tissue (e.g., for endangered species).

  1. Chloroplasts can move in any direction to avoid strong light.

    PubMed

    Tsuboi, Hidenori; Wada, Masamitsu

    2011-01-01

    Chloroplasts migrate in response to different light intensities. Under weak light, chloroplasts gather at an illuminated area to maximize light absorption and photosynthesis rates (the accumulation response). In contrast, chloroplasts escape from strong light to avoid photodamage (the avoidance response). Photoreceptors involved in these phenomena have been identified in Arabidopsis thaliana and Adiantum capillus-veneris. Chloroplast behavior has been studied in detail during the accumulation response, but not for the avoidance response. Hence, we analyzed the chloroplast avoidance response in detail using dark-adapted Adiantum capillus-veneris gametophyte cells and partial cell irradiation with a microbeam of blue light. Chloroplasts escaped from an irradiated spot. Both duration of this response and the distance of the migrated chloroplasts were proportional to the total fluence irradiated. The speed of movement during the avoidance response was dependent on the fluence rate, but the speed of the accumulation response towards the microbeam from cell periphery was constant irrespective of fluence rate. When a chloroplast was only partially irradiated with a strong microbeam, it moved away towards the non-irradiated region within a few minutes. During this avoidance response two additional microbeam irradiations were applied to different locus of the same chloroplast. Under these conditions the chloroplast changed the moving direction after a lag time of a few minutes without rolling. Taken together, these findings indicate that chloroplasts can move in any direction and never have an intrinsic polarity. Similar phenomenon was observed in chloroplasts of Arabidopsis thaliana palisade cells.

  2. A plastid protein NUS1 is essential for build-up of the genetic system for early chloroplast development under cold stress conditions.

    PubMed

    Kusumi, Kensuke; Sakata, Chikako; Nakamura, Takahiro; Kawasaki, Shinji; Yoshimura, Atsushi; Iba, Koh

    2011-12-01

    During early chloroplast differentiation, the regulation of the plastid genetic system including transcription and translation differs greatly from that in the mature chloroplast, suggesting the existence of a stage-dependent mechanism that regulates the chloroplast genetic system during this period. The virescent-1 (v(1)) mutant of rice (Oryza sativa) is temperature-conditional and develops chlorotic leaves under low-temperature conditions. We reported previously that leaf chlorosis in the v(1) mutant is caused by blockage of the activation of the chloroplast genetic system during early leaf development. Here we identify the V(1) gene, which encodes a chloroplast-localized protein NUS1. Accumulation of NUS1 specifically occurred in the pre-emerged immature leaves, and is enhanced by low-temperature treatment. The C-terminus of NUS1 shows structural similarity to the bacterial antitermination factor NusB, which is known to play roles in the regulation of ribosomal RNA transcription. The RNA-immunoprecipitation and gel mobility shift assays indicated that NUS1 binds to several regions of chloroplast RNA including the upstream leader region of the 16S rRNA precursor. In the leaves of the NUS1-deficient mutant, accumulation of chloroplast rRNA during early leaf development was impaired and chloroplast translation/transcription capacity was severely suppressed under low temperature. Our results suggest that NUS1 is involved in the regulation of chloroplast RNA metabolism and promotes the establishment of the plastid genetic system during early chloroplast development under cold stress conditions. © 2011 The Authors. The Plant Journal © 2011 Blackwell Publishing Ltd.

  3. Chloroplast signaling within, between and beyond cells

    PubMed Central

    Bobik, Krzysztof; Burch-Smith, Tessa M.

    2015-01-01

    The most conspicuous function of plastids is the oxygenic photosynthesis of chloroplasts, yet plastids are super-factories that produce a plethora of compounds that are indispensable for proper plant physiology and development. Given their origins as free-living prokaryotes, it is not surprising that plastids possess their own genomes whose expression is essential to plastid function. This semi-autonomous character of plastids requires the existence of sophisticated regulatory mechanisms that provide reliable communication between them and other cellular compartments. Such intracellular signaling is necessary for coordinating whole-cell responses to constantly varying environmental cues and cellular metabolic needs. This is achieved by plastids acting as receivers and transmitters of specific signals that coordinate expression of the nuclear and plastid genomes according to particular needs. In this review we will consider the so-called retrograde signaling occurring between plastids and nuclei, and between plastids and other organelles. Another important role of the plastid we will discuss is the involvement of plastid signaling in biotic and abiotic stress that, in addition to influencing retrograde signaling, has direct effects on several cellular compartments including the cell wall. We will also review recent evidence pointing to an intriguing function of chloroplasts in regulating intercellular symplasmic transport. Finally, we consider an intriguing yet less widely known aspect of plant biology, chloroplast signaling from the perspective of the entire plant. Thus, accumulating evidence highlights that chloroplasts, with their complex signaling pathways, provide a mechanism for exquisite regulation of plant development, metabolism and responses to the environment. As chloroplast processes are targeted for engineering for improved productivity the effect of such modifications on chloroplast signaling will have to be carefully considered in order to avoid

  4. Chloroplast-derived enzyme cocktails hydrolyse lignocellulosic biomass and release fermentable sugars.

    PubMed

    Verma, Dheeraj; Kanagaraj, Anderson; Jin, Shuangxia; Singh, Nameirakpam D; Kolattukudy, Pappachan E; Daniell, Henry

    2010-04-01

    It is widely recognized that biofuel production from lignocellulosic materials is limited by inadequate technology to efficiently and economically release fermentable sugars from the complex multi-polymeric raw materials. Therefore, endoglucanases, exoglucanase, pectate lyases, cutinase, swollenin, xylanase, acetyl xylan esterase, beta glucosidase and lipase genes from bacteria or fungi were expressed in Escherichia coli or tobacco chloroplasts. A PCR-based method was used to clone genes without introns from Trichoderma reesei genomic DNA. Homoplasmic transplastomic lines showed normal phenotype and were fertile. Based on observed expression levels, up to 49, 64 and 10, 751 million units of pectate lyases or endoglucanase can be produced annually, per acre of tobacco. Plant production cost of endoglucanase is 3100-fold, and pectate lyase is 1057 or 1480-fold lower than the same recombinant enzymes sold commercially, produced via fermentation. Chloroplast-derived enzymes had higher temperature stability and wider pH optima than enzymes expressed in E. coli. Plant crude-extracts showed higher enzyme activity than E. coli with increasing protein concentration, demonstrating their direct utility without purification. Addition of E. coli extracts to the chloroplast-derived enzymes significantly decreased their activity. Chloroplast-derived crude-extract enzyme cocktails yielded more (up to 3625%) glucose from filter paper, pine wood or citrus peel than commercial cocktails. Furthermore, pectate lyase transplastomic plants showed enhanced resistance to Erwina soft rot. This is the first report of using plant-derived enzyme cocktails for production of fermentable sugars from lignocellulosic biomass. Limitations of higher cost and lower production capacity of fermentation systems are addressed by chloroplast-derived enzyme cocktails.

  5. Chloroplast-derived enzyme cocktails hydrolyse lignocellulosic biomass and release fermentable sugars

    PubMed Central

    Verma, Dheeraj; Kanagaraj, Anderson; Jin, Shuangxia; Singh, Nameirakpam D.; Kolattukudy, Pappachan E; Daniell, Henry

    2009-01-01

    Summary It is widely recognized that biofuel production from lignocellulosic materials is limited by inadequate technology to efficiently and economically release fermentable sugars from the complex multi-polymeric raw materials. Therefore, endoglucanases, exoglucanase, pectate lyases, cutinase, swollenin, xylanase, acetyl xylan esterase, beta glucosidase and lipase genes from bacteria or fungi were expressed in E. coli or tobacco chloroplasts. A PCR based method was used to clone genes without introns from Trichoderma reesei genomic DNA. Homoplasmic transplastomic lines showed normal phenotype and were fertile. Based on observed expression levels, up to 49, 64 and 10,751 million units of pectate lyases or endoglucanase can be produced annually, per acre of tobacco. Plant production cost of endoglucanase is 3,100-fold and pectate lyase is 1,057 or 1,480 fold lower than the same recombinant enzymes sold commercially, produced via fermentation. Chloroplast-derived enzymes had higher temperature stability and wider pH optima than enzymes expressed in E. coli. Plant crude-extracts showed higher enzyme activity than E. coli with increasing protein concentration, demonstrating their direct utility without purification. Addition of E. coli extracts to the chloroplast-derived enzymes significantly decreased their activity. Chloroplast-derived crude-extract enzyme cocktails yielded more (up to 3,625%) glucose from filter paper, pine wood or citrus peel than commercial cocktails. Furthermore, pectate lyase transplastomic plants showed enhanced resistance to Erwina soft rot. This is the first report of using plant-derived enzyme cocktails for production of fermentable sugars from lignocellulosic biomass. Limitations of higher cost and lower production capacity of fermentation systems are addressed by chloroplast-derived enzyme cocktails. PMID:20070870

  6. Velocity of chloroplast avoidance movement is fluence rate dependent.

    PubMed

    Kagawa, Takatoshi; Wada, Masamitsu

    2004-06-01

    In Arabidopsis leaves, chloroplast movement is fluence rate dependent. At optimal, lower light fluences, chloroplasts accumulate at the cell surface to maximize photosynthetic potential. Under high fluence rates, chloroplasts avoid incident light to escape photodamage. In this paper, we examine the phenomenon of chloroplast avoidance movement in greater detail and demonstrate a proportional relationship between fluence rate and the velocity of chloroplast avoidance. In addition we show that the amount of light-activated phototropin2, the photoreceptor for the avoidance response, likely plays a role in this phenomenon, as heterozygous mutant plants show a reduced avoidance velocity compared to that of homozygous wild type plants.

  7. Lipid trafficking at endoplasmic reticulum-chloroplast membrane contact sites.

    PubMed

    Block, Maryse A; Jouhet, Juliette

    2015-08-01

    Glycerolipid synthesis in plant cells is characterized by an intense trafficking of lipids between the endoplasmic reticulum (ER) and chloroplasts. Initially, fatty acids are synthesized within chloroplasts and are exported to the ER where they are used to build up phospholipids and triacylglycerol. Ultimately, derivatives of these phospholipids return to chloroplasts to form galactolipids, monogalactosyldiacylglycerol and digalactosyldiacylglycerol, the main and essential lipids of photosynthetic membranes. Lipid trafficking was proposed to transit through membrane contact sites (MCSs) connecting both organelles. Here, we review recent insights into ER-chloroplast MCSs and lipid trafficking between chloroplasts and the ER.

  8. Chloroplast DNA diversity of the dioecious European tree Ilex aquifolium L. (English holly).

    PubMed

    Rendell, S; Ennos, R A

    2003-10-01

    Variation in the chloroplast genome of Ilex aquifolium (English holly), a dioecious evergreen tree native to south, west and central Europe, was analysed using polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLPs) and microsatellites. Differentiation between populations was high (GST = 0.595) and evidence for phylogeographical structure was detected (NST = 0.697, significantly higher than GST). Two chloroplast lineages were inferred originating from putative glacial refugia in southern Europe (Iberia, Italy and possibly the Balkans). The GST value was higher than reported for endozoochorous hermaphrodite species and for anemochorous dioecious species investigated over a similar geographical scale. It appears that dioecy has contributed to strong differentiation between refugia and that this has been maintained following postglacial recolonization as a result of limited seed flow. Palynological records for I. aquifolium are poor, thus these results give an important insight into patterns of glacial isolation and postglacial recolonization of this species.

  9. Chloroplast DNA codes for transfer RNA.

    PubMed Central

    McCrea, J M; Hershberger, C L

    1976-01-01

    Transfer RNA's were isolated from Euglena gracilis. Chloroplast cistrons for tRNA were quantitated by hybridizing tRNA to ct DNA. Species of tRNA hybridizing to ct DNA were partially purified by hybridization-chromatography. The tRNA's hybridizing to ct DNA and nuclear DNA appear to be different. Total cellular tRNA was hybridized to ct DNA to an equivalent of approximately 25 cistrons. The total cellular tRNA was also separated into 2 fractions by chromatography on dihydroxyboryl substituted amino ethyl cellulose. Fraction I hybridized to both nuclear and ct DNA. Hybridizations to ct DNA indicated approximately 18 cistrons. Fraction II-tRNA hybridized only to ct DNA, saturating at a level of approximately 7 cistrons. The tRNA from isolated chloroplasts hybridized to both chloroplast and nuclear DNA. The level of hybridization to ct DNA indicated approximately 18 cistrons. Fraction II-type tRNA could not be detected in the isolated chloroplasts. PMID:823529

  10. The evolution of chloroplast RNA editing.

    PubMed

    Tillich, Michael; Lehwark, Pascal; Morton, Brian R; Maier, Uwe G

    2006-10-01

    RNA editing alters the nucleotide sequence of an RNA molecule so that it deviates from the sequence of its DNA template. Different RNA-editing systems are found in the major eukaryotic lineages, and these systems are thought to have evolved independently. In this study, we provide a detailed analysis of data on C-to-U editing sites in land plant chloroplasts and propose a model for the evolution of RNA editing in land plants. First, our data suggest that the limited RNA-editing system of seed plants and the much more extensive systems found in hornworts and ferns are of monophyletic origin. Further, although some eukaryotic editing systems appear to have evolved to regulate gene expression, or at least are now involved in gene regulation, there is no evidence that RNA editing plays a role in gene regulation in land plant chloroplasts. Instead, our results suggest that land plant chloroplast C-to-U RNA editing originated as a mechanism to generate variation at the RNA level, which could complement variation at the DNA level. Under this model, many of the original sites, particularly in seed plants, have been subsequently lost due to mutation at the DNA level, and the function of extant sites is merely to conserve certain codons. This is the first comprehensive model for the evolution of the chloroplast RNA-editing system of land plants and may also be applicable to the evolution of RNA editing in plant mitochondria.

  11. Chloroplast DNA variation of northern red oak

    Treesearch

    Jeanne Romero-Severson; Preston Aldrich; Yi Feng; Weilin Sun; Charles Michler

    2003-01-01

    Chloroplast DNA (cpDNA) variation was examined in 48 northern red oaks at 14 sites representing contrasting glacial histories and age structures within the state of Indiana in the United States. PCR-RFLP of three intergenic regions revealed five haplotypes. Haplotype I was common to seven sites and was the most frequent (17 trees). Haplotype II was common to five sites...

  12. Chloroplast thioredoxin systems: prospects for improving photosynthesis.

    PubMed

    Nikkanen, Lauri; Toivola, Jouni; Diaz, Manuel Guinea; Rintamäki, Eevi

    2017-09-26

    Thioredoxins (TRXs) are protein oxidoreductases that control the structure and function of cellular proteins by cleavage of a disulphide bond between the side chains of two cysteine residues. Oxidized thioredoxins are reactivated by thioredoxin reductases (TR) and a TR-dependent reduction of TRXs is called a thioredoxin system. Thiol-based redox regulation is an especially important mechanism to control chloroplast proteins involved in biogenesis, in regulation of light harvesting and distribution of light energy between photosystems, in photosynthetic carbon fixation and other biosynthetic pathways, and in stress responses of plants. Of the two plant plastid thioredoxin systems, the ferredoxin-dependent system relays reducing equivalents from photosystem I via ferredoxin and ferredoxin-thioredoxin reductase (FTR) to chloroplast proteins, while NADPH-dependent thioredoxin reductase (NTRC) forms a complete thioredoxin system including both reductase and thioredoxin domains in a single polypeptide. Chloroplast thioredoxins transmit environmental light signals to biochemical reactions, which allows fine tuning of photosynthetic processes in response to changing environmental conditions. In this paper we focus on the recent reports on specificity and networking of chloroplast thioredoxin systems and evaluate the prospect of improving photosynthetic performance by modifying the activity of thiol regulators in plants.This article is part of the themed issue 'Enhancing photosynthesis in crop plants: targets for improvement'. © 2017 The Authors.

  13. From extracellular to intracellular: the establishment of mitochondria and chloroplasts.

    PubMed

    Whatley, J M; John, P; Whatley, F R

    1979-04-11

    Paracoccus and Rhodopseudomonas are unusual among bacteria in having a majority of the biochemical features of mitochondria; blue-green algae have many of the features of chloroplasts. The theory of serial endosymbiosis proposes that a primitive eukaryote successively took up bacteria and blue-green algae to yield mitochondria and chloroplasts respectively. Possible characteristics of transitional forms are indicated both by the primitive amoeba, Pelomyxa, which lacks mitochondria but contains a permanent population of endosymbiotic bacteria, and by several anomalous eukaryotic algae, e.g. Cyanophora, which contain cyanelles instead of chloroplasts. Blue-green algae appear to be obvious precursors of red algal chloroplasts but the ancestry of other chloroplasts is less certain, though the epizoic symbiont, Prochloron, may resemble the ancestral green algal chloroplast. We speculate that the chloroplasts of the remaining algae may have been a eukaryotic origin. The evolution or organelles from endosymbiotic precursors would involve their integration with the host cell biochemically, structurally and numerically.

  14. Regional differentiation and post-glacial expansion of the Atlantic silverside, Menidia menidia, an annual fish with high dispersal potential.

    PubMed

    Mach, Megan E; Sbrocco, Elizabeth J; Hice, Lyndie A; Duffy, Tara A; Conover, David O; Barber, Paul H

    2011-01-01

    The coastal marine environment of the Northwest Atlantic contains strong environmental gradients that create distinct marine biogeographic provinces by limiting dispersal, recruitment, and survival. This region has also been subjected to numerous Pleistocene glacial cycles, resulting in repeated extirpations and recolonizations in northern populations of marine organisms. In this study, we examined patterns of genetic structure and historical demography in the Atlantic silverside, Menidia menidia, an annual marine fish with high dispersal potential but with well-documented patterns of clinal phenotypic adaptation along the environmental gradients of the Northwest Atlantic. Contrary to previous studies indicating genetic homogeneity that should preclude regional adaptation, results demonstrate subtle but significant (FST = 0.07; P < 0.0001) genetic structure among three phylogeographic regions that partially correspond with biogeographic provinces, suggesting regional limits to gene flow. Tests for non-equilibrium population dynamics and latitudinal patterns in genetic diversity indicate northward population expansion from a single southern refugium following the last glacial maximum, suggesting that phylogeographic and phenotypic patterns have relatively recent origins. The recovery of phylogeographic structure and the partial correspondence of these regions to recognized biogeographic provinces suggest that the environmental gradients that shape biogeographic patterns in the Northwest Atlantic may also limit gene flow in M. menidia, creating phylogeographic structure and contributing to the creation of latitudinal phenotypic clines in this species.

  15. Phosphatidylcholine is transferred from chemically-defined liposomes to chloroplasts through proteins of the chloroplast outer envelope membrane.

    PubMed

    Yin, Congfei; Andersson, Mats X; Zhang, Hongsheng; Aronsson, Henrik

    2015-01-02

    Chloroplasts maintain their lipid balance through a tight interplay with the endoplasmic reticulum (ER). The outer envelope membrane of chloroplasts contains a large proportion of the phospholipid phosphatidylcholine (PC), which is synthesized in the ER and also a possible precursor for thylakoid galactolipids. The mechanism for PC transport from the ER to chloroplasts is not known. Using isolated chloroplasts and liposomes containing radiolabeled PC we investigated non-vesicular transport of PC in vitro. PC uptake in chloroplasts was time and temperature dependent, but nucleotide independent. Increased radius of liposomes stimulated PC uptake, and protease treatment of the chloroplasts impaired PC uptake. This implies that the chloroplast outer envelopes contains an exposed proteinaceous machinery for the uptake of PC from closely apposed membranes. Copyright © 2014 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  16. Effects of reduced chloroplast gene copy number on chloroplast gene expression in maize.

    PubMed

    Udy, Dylan B; Belcher, Susan; Williams-Carrier, Rosalind; Gualberto, José M; Barkan, Alice

    2012-11-01

    Chloroplasts and other members of the plastid organelle family contain a small genome of bacterial ancestry. Young chloroplasts contain hundreds of genome copies, but the functional significance of this high genome copy number has been unclear. We describe molecular phenotypes associated with mutations in a nuclear gene in maize (Zea mays), white2 (w2), encoding a predicted organellar DNA polymerase. Weak and strong mutant alleles cause a moderate (approximately 5-fold) and severe (approximately 100-fold) decrease in plastid DNA copy number, respectively, as assayed by quantitative PCR and Southern-blot hybridization of leaf DNA. Both alleles condition a decrease in most chloroplast RNAs, with the magnitude of the RNA deficiencies roughly paralleling that of the DNA deficiency. However, some RNAs are more sensitive to a decrease in genome copy number than others. The rpoB messenger RNA (mRNA) exhibited a unique response, accumulating to dramatically elevated levels in response to a moderate reduction in plastid DNA. Subunits of photosynthetic enzyme complexes were reduced more severely than were plastid mRNAs, possibly because of impaired translation resulting from limiting ribosomal RNA, transfer RNA, and ribosomal protein mRNA. These results indicate that chloroplast genome copy number is a limiting factor for the expression of a subset of chloroplast genes in maize. Whereas in Arabidopsis (Arabidopsis thaliana) a pair of orthologous genes function redundantly to catalyze DNA replication in both mitochondria and chloroplasts, the w2 gene is responsible for virtually all chloroplast DNA replication in maize. Mitochondrial DNA copy number was reduced approximately 2-fold in mutants harboring strong w2 alleles, suggesting that w2 also contributes to mitochondrial DNA replication.

  17. Transit peptide elements mediate selective protein targeting to two different types of chloroplasts in the single-cell C4 species Bienertia sinuspersici

    PubMed Central

    Wimmer, Diana; Bohnhorst, Philipp; Shekhar, Vinay; Hwang, Inhwan; Offermann, Sascha

    2017-01-01

    Bienertia sinuspersici is a terrestrial plant that performs C4 photosynthesis within individual cells through operating a carbon concentrating mechanism between different subcellular domains including two types of chloroplasts. It is currently unknown how differentiation of two highly specialized chloroplasts within the same cell occurs as no similar cases have been reported. Here we show that this differentiation in photosynthetic cells of B. sinuspersici is enabled by a transit peptide (TP) mediated selective protein targeting mechanism. Mutations in the TPs cause loss of selectivity but not general loss of chloroplast import, indicating the mechanism operates by specifically blocking protein accumulation in one chloroplast type. Hybrid studies indicate that this selectivity is transferable to transit peptides of plants which perform C4 by cooperative function of chloroplasts between two photosynthetic cells. Codon swap experiments as well as introducing an artificial bait mRNA show that RNA affects are not crucial for the sorting process. In summary, our analysis shows how the mechanism of subcellular targeting to form two types of chloroplast within the same cell can be achieved. This information is not only crucial for understanding single-cell C4 photosynthesis; it provides new insights in control of subcellular protein targeting in cell biology. PMID:28112241

  18. Analysis of Protein Import into Chloroplasts Isolated from Stressed Plants.

    PubMed

    Ling, Qihua; Jarvis, Paul

    2016-11-01

    Chloroplasts are organelles with many vital roles in plants, which include not only photosynthesis but numerous other metabolic and signaling functions. Furthermore, chloroplasts are critical for plant responses to various abiotic stresses, such as salinity and osmotic stresses. A chloroplast may contain up to ~3,000 different proteins, some of which are encoded by its own genome. However, the majority of chloroplast proteins are encoded in the nucleus and synthesized in the cytosol, and these proteins need to be imported into the chloroplast through translocons at the chloroplast envelope membranes. Recent studies have shown that the chloroplast protein import can be actively regulated by stress. To biochemically investigate such regulation of protein import under stress conditions, we developed the method described here as a quick and straightforward procedure that can easily be achieved in any laboratory. In this method, plants are grown under normal conditions and then exposed to stress conditions in liquid culture. Plant material is collected, and chloroplasts are then released by homogenization. The crude homogenate is separated by density gradient centrifugation, enabling isolation of the intact chloroplasts. Chloroplast yield is assessed by counting, and chloroplast intactness is checked under a microscope. For the protein import assays, purified chloroplasts are incubated with (35)S radiolabeled in vitro translated precursor proteins, and time-course experiments are conducted to enable comparisons of import rates between genotypes under stress conditions. We present data generated using this method which show that the rate of protein import into chloroplasts from a regulatory mutant is specifically altered under osmotic stress conditions.

  19. Polymorphic simple sequence repeat regions in chloroplast genomes: applications to the population genetics of pines.

    PubMed Central

    Powell, W; Morgante, M; McDevitt, R; Vendramin, G G; Rafalski, J A

    1995-01-01

    Simple sequence repeats (SSRs), consisting of tandemly repeated multiple copies of mono-, di-, tri-, or tetranucleotide motifs, are ubiquitous in eukaryotic genomes and are frequently used as genetic markers, taking advantage of their length polymorphism. We have examined the polymorphism of such sequences in the chloroplast genomes of plants, by using a PCR-based assay. GenBank searches identified the presence of several (dA)n.(dT)n mononucleotide stretches in chloroplast genomes. A chloroplast (cp) SSR was identified in three pine species (Pinus contorta, Pinus sylvestris, and Pinus thunbergii) 312 bp upstream of the psbA gene. DNA amplification of this repeated region from 11 pine species identified nine length variants. The polymorphic amplified fragments were isolated and the DNA sequence was determined, confirming that the length polymorphism was caused by variation in the length of the repeated region. In the pines, the chloroplast genome is transmitted through pollen and this PCR assay may be used to monitor gene flow in this genus. Analysis of 305 individuals from seven populations of Pinus leucodermis Ant. revealed the presence of four variants with intrapopulational diversities ranging from 0.000 to 0.629 and an average of 0.320. Restriction fragment length polymorphism analysis of cpDNA on the same populations previously failed to detect any variation. Population subdivision based on cpSSR was higher (Gst = 0.22, where Gst is coefficient of gene differentiation) than that revealed in a previous isozyme study (Gst = 0.05). We anticipate that SSR loci within the chloroplast genome should provide a highly informative assay for the analysis of the genetic structure of plant populations. Images Fig. 2 PMID:7644491

  20. A family of selfish minicircular chromosomes with jumbled chloroplast gene fragments from a dinoflagellate.

    PubMed

    Zhang, Z; Cavalier-Smith, T; Green, B R

    2001-08-01

    Chloroplast genes of several dinoflagellate species are located on unigenic DNA minicircular chromosomes. We have now completely sequenced five aberrant minicircular chromosomes from the dinoflagellate Heterocapsa triquetra. These probably nonfunctional DNA circles lack complete genes, with each being composed of several short fragments of two or three different chloroplast genes and a common conserved region with a tripartite 9G-9A-9G core like the putative replicon origin of functional single-gene circular chloroplast chromosomes. Their sequences imply that all five circles evolved by differential deletions and duplications from common ancestral circles bearing fragments of four genes: psbA, psbC, 16S rRNA, and 23S rRNA. It appears that recombination between separate unigenic chromosomes initially gave intermediate heterodimers, which were subsequently stabilized by deletions that included part or all of one putative replicon origin. We suggest that homologous recombination at the 9G-9A-9G core regions produced a psbA/psbC heterodimer which generated two distinct chimeric circles by differential deletions and duplications. A 23S/16S rRNA heterodimer more likely formed by illegitimate recombination between 16S and 23S rRNA genes. Homologous recombination between the 9G-9A-9G core regions of both heterodimers and additional differential deletions and duplications could then have yielded the other three circles. Near identity of the gene fragments and 9G-9A-9G cores, despite diverging adjacent regions, may be maintained by gene conversion. The conserved organization of the 9G-9A-9G cores alone favors the idea that they are replicon origins and suggests that they may enable the aberrant minicircles to parasitize the chloroplast's replication machinery as selfish circles.

  1. Molecular characterization of transketolase (EC 2.2.1.1) active in the Calvin cycle of spinach chloroplasts.

    PubMed

    Flechner, A; Dressen, U; Westhoff, P; Henze, K; Schnarrenberger, C; Martin, W

    1996-11-01

    A cDNA encoding the Calvin cycle enzyme transketolase (TKL; EC 2.2.1.1) was isolated from Sorghum bicolor via subtractive differential hybridization, and used to isolate several full-length cDNA clones for this enzyme from spinach. Functional identity of the encoded mature subunit was shown by an 8.6-fold increase of TKL activity upon induction of Escherichia coli cells that overexpress the spinach TKL subunit under the control of the bacteriophage T7 promoter. Chloroplast localization of the cloned enzyme is shown by processing of the in vitro synthesized precursor upon uptake by isolated chloroplasts. Southern blot-analysis suggests that TKL is encoded by a single gene in the spinach genome. TKL proteins of both higher-plant chloroplasts and the cytosol of non-photosynthetic eukaryotes are found to be unexpectedly similar to eubacterial homologues, suggesting a possible eubacterial origin of these nuclear genes. Chloroplast TKL is the last of the demonstrably chloroplast-localized Calvin cycle enzymes to have been cloned and thus completes the isolation of gene probes for all enzymes of the pathway in higher plants.

  2. Population differentiation for germination and early seedling root growth traits under saline conditions in the annual legume Medicago truncatula (Fabaceae).

    PubMed

    Cordeiro, Matilde A; Moriuchi, Ken S; Fotinos, Tonya D; Miller, Kelsey E; Nuzhdin, Sergey V; von Wettberg, Eric J; Cook, Douglas R

    2014-03-01

    Seedling establishment and survival are highly sensitive to soil salinity and plants that evolved in saline environments are likely to express traits that increase fitness in those environments. Such traits are of ecological interest and they may have practical value for improving salt tolerance in cultivated species. We examined responses to soil salinity and tested potential mechanisms of salt tolerance in Medicago truncatula, using genotypes that originated from natural populations occurring on saline and nonsaline soils. Germination and seedling responses were quantified and compared between saline and nonsaline origin genotypes. Germination treatments included a range of sodium chloride (NaCl) concentrations in both offspring and parental environments. Seedling treatments included NaCl, abscisic acid (ABA), and potassium chloride (KCl). Saline origin genotypes displayed greater salinity tolerance for germination and seedling traits relative to nonsaline origin genotypes. We observed population specific differences for the effects of salinity on time to germination and for the impact of parental environment on germination rates. ABA and NaCl treatments had similar negative effects on root growth, although relative sensitivities differed, with saline population less sensitive to NaCl and more sensitive to ABA compared to their nonsaline counterparts. We report population differentiation for germination and seedling growth traits under saline conditions among populations derived from saline and nonsaline environments. These observations are consistent with a syndrome of adaptations for salinity tolerance during early plant development, including traits that are common among saline environments and those that are idiosyncratic to local populations.

  3. Direct Chloroplast Sequencing: Comparison of Sequencing Platforms and Analysis Tools for Whole Chloroplast Barcoding

    PubMed Central

    Brozynska, Marta; Furtado, Agnelo; Henry, Robert James

    2014-01-01

    Direct sequencing of total plant DNA using next generation sequencing technologies generates a whole chloroplast genome sequence that has the potential to provide a barcode for use in plant and food identification. Advances in DNA sequencing platforms may make this an attractive approach for routine plant identification. The HiSeq (Illumina) and Ion Torrent (Life Technology) sequencing platforms were used to sequence total DNA from rice to identify polymorphisms in the whole chloroplast genome sequence of a wild rice plant relative to cultivated rice (cv. Nipponbare). Consensus chloroplast sequences were produced by mapping sequence reads to the reference rice chloroplast genome or by de novo assembly and mapping of the resulting contigs to the reference sequence. A total of 122 polymorphisms (SNPs and indels) between the wild and cultivated rice chloroplasts were predicted by these different sequencing and analysis methods. Of these, a total of 102 polymorphisms including 90 SNPs were predicted by both platforms. Indels were more variable with different sequencing methods, with almost all discrepancies found in homopolymers. The Ion Torrent platform gave no apparent false SNP but was less reliable for indels. The methods should be suitable for routine barcoding using appropriate combinations of sequencing platform and data analysis. PMID:25329378

  4. Ions channels/transporters and chloroplast regulation.

    PubMed

    Finazzi, Giovanni; Petroutsos, Dimitris; Tomizioli, Martino; Flori, Serena; Sautron, Emeline; Villanova, Valeria; Rolland, Norbert; Seigneurin-Berny, Daphné

    2015-07-01

    Ions play fundamental roles in all living cells and their gradients are often essential to fuel transports, to regulate enzyme activities and to transduce energy within and between cells. Their homeostasis is therefore an essential component of the cell metabolism. Ions must be imported from the extracellular matrix to their final subcellular compartments. Among them, the chloroplast is a particularly interesting example because there, ions not only modulate enzyme activities, but also mediate ATP synthesis and actively participate in the building of the photosynthetic structures by promoting membrane-membrane interaction. In this review, we first provide a comprehensive view of the different machineries involved in ion trafficking and homeostasis in the chloroplast, and then discuss peculiar functions exerted by ions in the frame of photochemical conversion of absorbed light energy.

  5. Protein trafficking to the complex chloroplasts of Euglena.

    PubMed

    Vacula, Rostislav; Sláviková, Silvia; Schwartzbach, Steven D

    2007-01-01

    Proteins are delivered to Euglena chloroplasts using the secretory pathway. We describe analytical methods to study the intracellular trafficking of Euglena chloroplast proteins and a method to isolate preparative amounts of intact import competent chloroplasts for biochemical studies. Cells are pulse labeled with 35S-sulfate and chased with unlabeled sulfate allowing the trafficking and posttranslational processing of the labeled protein to be followed. Sucrose gradients are used to separate a 35S-labeled cell lysate into cytoplasmic, endoplasmic reticuum (ER), Golgi apparatus, chloroplast and mitochondrial fractions. Immunoprecipitation of each gradient fraction allows identification of the intracellular compartment containing a specific 35S-labeled protein at different times after synthesis delineating the trafficking pathway. Because sucrose gradients cannot be used to isolate preparative amounts of highly purified chloroplasts for biochemical characterization, a preparative high-yield procedure using Percoll gradients to isolate highly purified import competent chloroplasts is also presented.

  6. [Thermoluminescence and electric polarization in chloroplasts].

    PubMed

    Noks, P P; Venediktov, P S; Kononenko, A A; Rubin, A B; Garab, D

    1984-01-01

    Exposure of pea chloroplasts to electric field causes the appearance of a new thermoluminescence (TL) band at--(40-50) degrees C and a reduction of the intensity of its main bands. Extents of intensity drop are different for different components of TL and depend on the temperature of illumination. The charge traps responsible for the individual TL components seem to be localized in microsurroundings having different field susceptibility. The electric field effects observable at different temperatures are in correlation with the thermodepolarization currents which reflect the mobility and number of charged groups undergoing a field-induced displacement in chloroplast membranes. Dehydration. of chloroplast film preparations causes a reduction in the intensities of the TL peaks and thermodepolarization currents and a shift of the peaks positions toward higher temperatures. It is assumed that the traps of the recombining charges have two different conformations, each with its own frequency factor for the recombination reaction. Changes in the thermoluminescence behavior in applied electric field are due to the polarization of the traps, which increases the existence probability of a conformation with a high frequency factor.

  7. Protein methylation in pea chloroplasts. [Pisum sativum

    SciTech Connect

    Niemi, K.J.; Adler, J.; Selman, B.R. )

    1990-07-01

    The methylation of chloroplast proteins has been investigated by incubating intact pea (Pisum sativum) chloroplasts with ({sup 3}H-methyl)-S-adenosylmethionine. Incubation in the light increases the amount of methylation in both the thylakoid and stromal fractions. Numerous thylakoid proteins serve as substrates for the methyltransfer reactions. Three of these thylakoid proteins are methylated to a significantly greater extent in the light than in the dark. The primary stromal polypeptide methylated is the large subunit of ribulose bisphosphate carboxylase/oxygenase. One other stromal polypeptide is also methylated much more in the light than in the dark. Two distinct types of protein methylation occur. One methylinkage is stable to basic conditions whereas a second type is base labile. The base-stable linkage is indicative of N-methylation of amino acid residues while base-lability is suggestive of carboxymethylation of amino acid residues. Labeling in the light increases the percentage of methylation that is base labile in the thylakoid fraction while no difference is observed in the amount of base-labile methylations in light-labeled and dark-labeled stromal proteins. Also suggestive of carboxymethylation is the detection of volatile ({sup 3}H)methyl radioactivity which increases during the labeling period and is greater in chloroplasts labeled in the light as opposed to being labeled in the dark; this implies in vivo turnover of the ({sup 3}H)methyl group.

  8. Phosphatidylinositol 4-phosphate negatively regulates chloroplast division in Arabidopsis.

    PubMed

    Okazaki, Kumiko; Miyagishima, Shin-ya; Wada, Hajime

    2015-03-01

    Chloroplast division is performed by the constriction of envelope membranes at the division site. Although constriction of a ring-like protein complex has been shown to be involved in chloroplast division, it remains unknown how membrane lipids participate in the process. Here, we show that phosphoinositides with unknown function in envelope membranes are involved in the regulation of chloroplast division in Arabidopsis thaliana. PLASTID DIVISION1 (PDV1) and PDV2 proteins interacted specifically with phosphatidylinositol 4-phosphate (PI4P). Inhibition of phosphatidylinositol 4-kinase (PI4K) decreased the level of PI4P in chloroplasts and accelerated chloroplast division. Knockout of PI4Kβ2 expression or downregulation of PI4Kα1 expression resulted in decreased levels of PI4P in chloroplasts and increased chloroplast numbers. PI4Kα1 is the main contributor to PI4P synthesis in chloroplasts, and the effect of PI4K inhibition was largely abolished in the pdv1 mutant. Overexpression of DYNAMIN-RELATED PROTEIN5B (DRP5B), another component of the chloroplast division machinery, which is recruited to chloroplasts by PDV1 and PDV2, enhanced the effect of PI4K inhibition, whereas overexpression of PDV1 and PDV2 had additive effects. The amount of DRP5B that associated with chloroplasts increased upon PI4K inhibition. These findings suggest that PI4P is a regulator of chloroplast division in a PDV1- and DRP5B-dependent manner. © 2015 American Society of Plant Biologists. All rights reserved.

  9. Chloroplast targeting factor AKR2 evolved from an ankyrin repeat domain coincidentally binds two chloroplast lipids

    PubMed Central

    Kim, Dae Heon; Park, Mi-Jeong; Gwon, Gwang Hyeon; Silkov, Antonina; Xu, Zheng-Yi; Yang, Eun Chan; Song, Seohyeon; Song, Kyungyoung; Kim, Younghyun; Yoon, Hwan Su; Honig, Barry; Cho, Wonhwa; Cho, Yunje; Hwang, Inhwan

    2014-01-01

    SUMMARY In organellogenesis of the chloroplast from endosymbiotic cyanobacterium, the establishment of protein targeting mechanisms to the chloroplast should have been pivotal. However, it is still mysterious how these mechanisms were established and how they work in plant cells. Here, we show that AKR2A, the cytosolic targeting factor for chloroplast outer membrane (COM) proteins, evolved from the ankyrin repeat domain (ARD) of the host cell by stepwise extensions of its N-terminal domain, and two lipids monogalactosyldiacylglycerol (MGDG) and phosphatidylglycerol (PG) of the endosymbiont were selected to function as the AKR2A receptor. Structural analysis, molecular modeling and mutational analysis of the ARD identified two adjacent sites for coincidental and synergistic binding of MGDG and PG. Based on these findings, we propose that the targeting mechanism of COM proteins was established using components from both the endosymbiont and host cell through a modification of the protein-protein interacting ARD into a lipid binding domain. PMID:25203210

  10. Cadmium accumulation in chloroplasts and its impact on chloroplastic processes in barley and maize.

    PubMed

    Lysenko, Eugene A; Klaus, Alexander A; Pshybytko, Natallia L; Kusnetsov, Victor V

    2015-08-01

    Data on cadmium accumulation in chloroplasts of terrestrial plants are scarce and contradictory. We introduced CdSO4 in hydroponic media to the final concentrations 80 and 250 μM and studied the accumulation of Cd in chloroplasts of Hordeum vulgare and Zea mays. Barley accumulated more Cd in the chloroplasts as compared to maize, whereas in the leaves cadmium accumulation was higher in maize. The cadmium content in the chloroplasts of two species varied from 49 to 171 ng Cd/mg chlorophyll, which corresponds to one Cd atom per 728-2,540 chlorophyll molecules. Therefore, Mg(2+) can be substituted by Cd(2+) in a negligible amount of antenna chlorophylls only. The percentage of chloroplastic cadmium can be estimated as 0.21-1.32 % of all the Cd in a leaf. Photochemistry (F v/F m, ΦPSII, qP) was not influenced by Cd. Non-photochemical quenching of chlorophyll-excited state (NPQ) was greatly reduced in barley but not in maize. The decrease in NPQ was due to its fast relaxing component; the slow relaxing component rose slightly. In chloroplasts, Cd did not affect mRNA levels, but content of some photosynthetic proteins was reduced: slightly in the leaves of barley and heavily in the leaves of maize. In all analyzed C3-species, the effect of Cd on the content of photosynthetic proteins was mild or absent. This is most likely the first evidence of severe reduction of photosynthetic proteins in leaves of a Cd-treated C4-plant.

  11. Nanophotonics of Chloroplasts for Bio-Inspired Solar Energy Materials

    NASA Astrophysics Data System (ADS)

    Gourley, Paul L.; Gourley, Cheryl R.

    2011-03-01

    In the search for new energy sources, lessons can be learned from chloroplast photonics. The nano-architecture of chloroplasts is remarkably well-adapted to mediate sunlight interactions for efficient energy conversion. We carried out experiments with chloroplasts isolated from spinach and leaf lettuce to elucidate the relationship between nano-architecture, biomolecular composition and photonic properties. We obtained high-resolution microscopic images of single chloroplasts to identify geometries of chloroplasts and interior grana. We performed micro-spectroscopy to identify strengths of absorption and fluorescence transitions and related them to broadband reflectance and transmittance spectra of whole leaf structures. Finally, the nonlinear optical properties were investigated with nanolaser spectroscopy by placing chloroplasts into micro-resonators and optically pumping. These spectra reveal chloroplast photonic modes and allow measurement of single chloroplast light scattering cross section, polarizability, and refractive index. The nanolaser spectra recorded at increasing pump powers enabled us to observe non-linear optics, photon dynamics, and stimulated emission from single chloroplasts. All of these experiments provide insight into plant photonics and inspiration of paradigms for synthetic biomaterials to harness sunlight in new ways.

  12. Looking for a substituent of spinach (Spinacia oleracea) chloroplasts

    NASA Astrophysics Data System (ADS)

    Chang, Ying Ping; Yeoh, Loo Yew; Chee, Swee Yong; Lim, Tuck Meng

    2017-04-01

    Spinach's chloroplasts electron transport features are often adapted to build biofuel cells or biosensors for environment conservation. This approach may raise food security issues. The present study aimed to test on in vitro functional activity of chloroplasts from selected underutilized leaves of: Pandan (Pandanus amaryllifolius), oil palm (Elaeis guineensis) and water lettuce (Pistia stratiotes) in comparison with spinach (Spinacia oleracea). The leaves' electrical conductivity was measured to evaluate the initial cell permeability. We applied Hill's reaction to determine the photoreduction capacity of the chloroplasts. Initial electrical conductivity of leaves ranged from 11.5 to 18.5 µs/cm/g followed the order of water lettucechloroplasts. Chloroplasts of oil palm frond and water lettuce showed low photoreduction rate of 14 to 22%. On the other hand, the chloroplasts of both spinach and pandan leaves exerted an initial photoreduction rate which was above 90%. The photoreduction rate of these chloroplasts remained to above 60% even after 30 day-storage at -20°C. In comparison with spinach, pandan leaves' chloroplasts possessed similar in vitro functional activity and storage stability at 4°C and -20°C. This warrants further investigation on chloroplasts of pandan leaves for higher-value applications.

  13. Copper Delivery to Chloroplast Proteins and its Regulation

    PubMed Central

    Aguirre, Guadalupe; Pilon, Marinus

    2016-01-01

    Copper is required for photosynthesis in chloroplasts of plants because it is a cofactor of plastocyanin, an essential electron carrier in the thylakoid lumen. Other chloroplast copper proteins are copper/zinc superoxide dismutase and polyphenol oxidase, but these proteins seem to be dispensable under conditions of low copper supply when transcripts for these proteins undergo microRNA-mediated down regulation. Two ATP-driven copper transporters function in tandem to deliver copper to chloroplast compartments. This review seeks to summarize the mechanisms of copper delivery to chloroplast proteins and its regulation. We also delineate some of the unanswered questions that still remain in this field. PMID:26793223

  14. Fine tuning chloroplast movements through physical interactions between phototropins

    PubMed Central

    Sztatelman, Olga; Łabuz, Justyna; Hermanowicz, Paweł; Banaś, Agnieszka Katarzyna; Bażant, Aneta; Zgłobicki, Piotr; Aggarwal, Chhavi; Nadzieja, Marcin; Krzeszowiec, Weronika; Strzałka, Wojciech; Gabryś, Halina

    2016-01-01

    Phototropins are plant photoreceptors which regulate numerous responses to blue light, including chloroplast relocation. Weak blue light induces chloroplast accumulation, whereas strong light leads to an avoidance response. Two Arabidopsis phototropins are characterized by different light sensitivities. Under continuous light, both can elicit chloroplast accumulation, but the avoidance response is controlled solely by phot2. As well as continuous light, brief light pulses also induce chloroplast displacements. Pulses of 0.1s and 0.2s of fluence rate saturating the avoidance response lead to transient chloroplast accumulation. Longer pulses (up to 20s) trigger a biphasic response, namely transient avoidance followed by transient accumulation. This work presents a detailed study of transient chloroplast responses in Arabidopsis. Phototropin mutants display altered chloroplast movements as compared with the wild type: phot1 is characterized by weaker responses, while phot2 exhibits enhanced chloroplast accumulation, especially after 0.1s and 0.2s pulses. To determine the cause of these differences, the abundance and phosphorylation levels of both phototropins, as well as the interactions between phototropin molecules are examined. The formation of phototropin homo- and heterocomplexes is the most plausible explanation of the observed phenomena. The physiological consequences of this interplay are discussed, suggesting the universal character of this mechanism that fine-tunes plant reactions to blue light. Additionally, responses in mutants of different protein phosphatase 2A subunits are examined to assess the role of protein phosphorylation in signaling of chloroplast movements. PMID:27406783

  15. New insights into dynamic actin-based chloroplast photorelocation movement.

    PubMed

    Kong, Sam-Geun; Wada, Masamitsu

    2011-09-01

    Chloroplast movement is essential for plants to survive under various environmental light conditions. Phototropins-plant-specific blue-light-activated receptor kinases-mediate the response by perceiving light intensity and direction. Recently, novel chloroplast actin (cp-actin) filaments have been identified as playing a pivotal role in the directional chloroplast photorelocation movement. Encouraging progress has recently been made in this field of research through molecular genetics and cell biological analyses. This review describes factors that have been identified as being involved in chloroplast movement and their roles in the regulation of cp-actin filaments, thus providing a basis for reflection on their biochemical activities and functions.

  16. The complete chloroplast genome of Phalaenopsis "Tiny Star".

    PubMed

    Kim, Goon-Bo; Kwon, Youngeun; Yu, Hee-Ju; Lim, Ki-Byung; Seo, Jae-Hwan; Mun, Jeong-Hwan

    2016-01-01

    We determined the complete chloroplast DNA sequence of Phalaenopsis "Tiny Star" based on Illumina sequencing. The total length of the chloroplast genome is 148,918 bp long with GC content of 36.7%. It contains 70 protein-coding genes, 30 tRNA genes, and 4 rRNA genes. Comparative analysis with the reported orchid chloroplast sequences identified unique InDel variations in the "Tiny Star" chloroplast genome that have potential as genetic markers to investigate the maternal lineage of Phalaenopsis and Doritaenopsis cultivars.

  17. Uptake and incorporation of iron in sugar beet chloroplasts.

    PubMed

    Solti, Adám; Kovács, Krisztina; Basa, Brigitta; Vértes, Attila; Sárvári, Eva; Fodor, Ferenc

    2012-03-01

    Chloroplasts contain 80-90% of iron taken up by plant cells. Though some iron transport-related envelope proteins were identified recently, the mechanism of iron uptake into chloroplasts remained unresolved. To shed more light on the process of chloroplast iron uptake, trials were performed with isolated intact chloroplasts of sugar beet (Beta vulgaris). Iron uptake was followed by measuring the iron content of chloroplasts in the form of ferrous-bathophenantroline-disulphonate complex after solubilising the chloroplasts in reducing environment. Ferric citrate was preferred to ferrous citrate as substrate for chloroplasts. Strong dependency of ferric citrate uptake on photosynthetic electron transport activity suggests that ferric chelate reductase uses NADPH, and is localised in the inner envelope membrane. The K(m) for iron uptake from ferric-citrate pool was 14.65 ± 3.13 μM Fe((III))-citrate. The relatively fast incorporation of (57)Fe isotope into Fe-S clusters/heme, detected by Mössbauer spectroscopy, showed the efficiency of the biosynthetic machinery of these cofactors in isolated chloroplasts. The negative correlation between the chloroplast iron concentration and the rate of iron uptake refers to a strong feedback regulation of the uptake. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

  18. A role for mechanosensitive channels in chloroplast and bacterial fission.

    PubMed

    Wilson, Margaret; Haswell, Elizabeth

    2012-02-01

    The division site in both chloroplasts and bacteria is established by the medial placement of the FtsZ ring, a process that is in part regulated by the evolutionarily conserved components of the Min system. We recently showed that mechanosensitive ion channels influence FtsZ ring assembly in both Arabidopsis thaliana chloroplasts and in Escherichia coli; in chloroplasts they do so through the same genetic pathway as the Min system. Here we describe the effect of heterologous expression of the Arabidopsis MS channel homolog MSL2 on FtsZ ring placement in E. coli. We also discuss possible molecular mechanisms by which MS channels might influence chloroplast or bacterial division.

  19. Copper Delivery to Chloroplast Proteins and its Regulation.

    PubMed

    Aguirre, Guadalupe; Pilon, Marinus

    2015-01-01

    Copper is required for photosynthesis in chloroplasts of plants because it is a cofactor of plastocyanin, an essential electron carrier in the thylakoid lumen. Other chloroplast copper proteins are copper/zinc superoxide dismutase and polyphenol oxidase, but these proteins seem to be dispensable under conditions of low copper supply when transcripts for these proteins undergo microRNA-mediated down regulation. Two ATP-driven copper transporters function in tandem to deliver copper to chloroplast compartments. This review seeks to summarize the mechanisms of copper delivery to chloroplast proteins and its regulation. We also delineate some of the unanswered questions that still remain in this field.

  20. Mutations That Alter the Transmission of Chloroplast Genes in Chlamydomonas

    PubMed Central

    Sager, Ruth; Ramanis, Zenta

    1974-01-01

    Two mutations are described that alter the pattern of inheritance of chloroplast genes in Chlamydomonas. The mutant gene mat-1 linked to the mating type allele mt- greatly increases the frequency of exceptional zygotes, i.e., zygotes that transmit chloroplast genes from the mt- (male) parent. In some crosses, 80-90% of the zygotes are biparental, transmitting chloroplast genes from both parents. The mat-2 mutation, linked to mt+, acts to decrease the frequency of exceptional zygotes below the spontaneous level. The mutant effects are discussed in terms of a DNA modification-restriction system, postulated to regulate the transmission of chloroplast DNA in zygotes. PMID:4531010

  1. Complex chloroplast RNA metabolism: just debugging the genetic programme?

    PubMed Central

    Maier, Uwe G; Bozarth, Andrew; Funk, Helena T; Zauner, Stefan; Rensing, Stefan A; Schmitz-Linneweber, Christian; Börner, Thomas; Tillich, Michael

    2008-01-01

    Background The gene expression system of chloroplasts is far more complex than that of their cyanobacterial progenitor. This gain in complexity affects in particular RNA metabolism, specifically the transcription and maturation of RNA. Mature chloroplast RNA is generated by a plethora of nuclear-encoded proteins acquired or recruited during plant evolution, comprising additional RNA polymerases and sigma factors, and sequence-specific RNA maturation factors promoting RNA splicing, editing, end formation and translatability. Despite years of intensive research, we still lack a comprehensive explanation for this complexity. Results We inspected the available literature and genome databases for information on components of RNA metabolism in land plant chloroplasts. In particular, new inventions of chloroplast-specific mechanisms and the expansion of some gene/protein families detected in land plants lead us to suggest that the primary function of the additional nuclear-encoded components found in chloroplasts is the transgenomic suppression of point mutations, fixation of which occurred due to an enhanced genetic drift exhibited by chloroplast genomes. We further speculate that a fast evolution of transgenomic suppressors occurred after the water-to-land transition of plants. Conclusion Our inspections indicate that several chloroplast-specific mechanisms evolved in land plants to remedy point mutations that occurred after the water-to-land transition. Thus, the complexity of chloroplast gene expression evolved to guarantee the functionality of chloroplast genetic information and may not, with some exceptions, be involved in regulatory functions. PMID:18755031

  2. The chloroplast ATP synthase features the characteristic redox regulation machinery.

    PubMed

    Hisabori, Toru; Sunamura, Ei-Ichiro; Kim, Yusung; Konno, Hiroki

    2013-11-20

    Regulation of the activity of the chloroplast ATP synthase is largely accomplished by the chloroplast thioredoxin system, the main redox regulation system in chloroplasts, which is directly coupled to the photosynthetic reaction. We review the current understanding of the redox regulation system of the chloroplast ATP synthase. The thioredoxin-targeted portion of the ATP synthase consists of two cysteines located on the central axis subunit γ. The redox state of these two cysteines is under the influence of chloroplast thioredoxin, which directly controls rotation during catalysis by inducing a conformational change in this subunit. The molecular mechanism of redox regulation of the chloroplast ATP synthase has recently been determined. Regulation of the activity of the chloroplast ATP synthase is critical in driving efficiency into the ATP synthesis reaction in chloroplasts. The molecular architecture of the chloroplast ATP synthase, which confers redox regulatory properties requires further investigation, in light of the molecular structure of the enzyme complex as well as the physiological significance of the regulation system.

  3. Field production and functional evaluation of chloroplast-derived interferon-α2b

    PubMed Central

    Arlen, Philip A.; Falconer, Regina; Cherukumilli, Sri; Cole, Amy; Cole, Alexander M.; Oishi, Karen K.; Daniell, Henry

    2008-01-01

    Summary Type I interferons (IFNs) inhibit viral replication and cell growth and enhance the immune response, and therefore have many clinical applications. IFN-α2b ranks third in world market use for a biopharmaceutical, behind only insulin and erythropoietin. The average annual cost of IFN-α2b for the treatment of hepatitis C infection is $26 000, and is therefore unavailable to the majority of patients in developing countries. Therefore, we expressed IFN-α2b in tobacco chloroplasts, and transgenic lines were grown in the field after obtaining United States Department of Agriculture Animal and Plant Health Inspection Service (USDA-APHIS) approval. Stable, site-specific integration of transgenes into chloroplast genomes and homoplasmy through several generations were confirmed. IFN-α2b levels reached up to 20% of total soluble protein, or 3 mg per gram of leaf (fresh weight). Transgenic IFN-α2b had similar in vitro biological activity to commercially produced PEG-Intron™ when tested for its ability to protect cells against cytopathic viral replication in the vesicular stomatitis virus cytopathic effect (VSV CPE) assay and to inhibit early-stage human immunodeficiency virus (HIV) infection. The antitumour and immunomodulating properties of IFN-α2b were also seen in vivo . Chloroplast-derived IFN-α2b increased the expression of major histocompatibility complex class I (MHC I) on splenocytes and the total number of natural killer (NK) cells. Finally, IFN-α2b purified from chloroplast transgenic lines (cpIFN-α2b) protected mice from a highly metastatic tumour line. This demonstration of high levels of expression of IFN-α2b, transgene containment and biological activity akin to that of commercial preparations of IFN-α2b facilitated the first field production of a plant-derived human blood protein, a critical step towards human clinical trials and commercialization. PMID:17490449

  4. Analyses of the complete genome and gene expression of chloroplast of sweet potato [Ipomoea batata].

    PubMed

    Yan, Lang; Lai, Xianjun; Li, Xuedan; Wei, Changhe; Tan, Xuemei; Zhang, Yizheng

    2015-01-01

    Sweet potato [Ipomoea batatas (L.) Lam] ranks among the top seven most important food crops cultivated worldwide and is hexaploid plant (2n=6x=90) in the Convolvulaceae family with a genome size between 2,200 to 3,000 Mb. The genomic resources for this crop are deficient due to its complicated genetic structure. Here, we report the complete nucleotide sequence of the chloroplast (cp) genome of sweet potato, which is a circular molecule of 161,303 bp in the typical quadripartite structure with large (LSC) and small (SSC) single-copy regions separated by a pair of inverted repeats (IRs). The chloroplast DNA contains a total of 145 genes, including 94 protein-encoding genes of which there are 72 single-copy and 11 double-copy genes. The organization and structure of the chloroplast genome (gene content and order, IR expansion/contraction, random repeating sequences, structural rearrangement) of sweet potato were compared with those of Ipomoea (L.) species and some basal important angiosperms, respectively. Some boundary gene-flow and gene gain-and-loss events were identified at intra- and inter-species levels. In addition, by comparing with the transcriptome sequences of sweet potato, the RNA editing events and differential expressions of the chloroplast functional-genes were detected. Moreover, phylogenetic analysis was conducted based on 77 protein-coding genes from 33 taxa and the result may contribute to a better understanding of the evolution progress of the genus Ipomoea (L.), including phylogenetic relationships, intraspecific differentiation and interspecific introgression.

  5. Analyses of the Complete Genome and Gene Expression of Chloroplast of Sweet Potato [Ipomoea batata

    PubMed Central

    Yan, Lang; Lai, Xianjun; Li, Xuedan; Wei, Changhe; Tan, Xuemei; Zhang, Yizheng

    2015-01-01

    Sweet potato [Ipomoea batatas (L.) Lam] ranks among the top seven most important food crops cultivated worldwide and is hexaploid plant (2n=6x=90) in the Convolvulaceae family with a genome size between 2,200 to 3,000 Mb. The genomic resources for this crop are deficient due to its complicated genetic structure. Here, we report the complete nucleotide sequence of the chloroplast (cp) genome of sweet potato, which is a circular molecule of 161,303 bp in the typical quadripartite structure with large (LSC) and small (SSC) single-copy regions separated by a pair of inverted repeats (IRs). The chloroplast DNA contains a total of 145 genes, including 94 protein-encoding genes of which there are 72 single-copy and 11 double-copy genes. The organization and structure of the chloroplast genome (gene content and order, IR expansion/contraction, random repeating sequences, structural rearrangement) of sweet potato were compared with those of Ipomoea (L.) species and some basal important angiosperms, respectively. Some boundary gene-flow and gene gain-and-loss events were identified at intra- and inter-species levels. In addition, by comparing with the transcriptome sequences of sweet potato, the RNA editing events and differential expressions of the chloroplast functional-genes were detected. Moreover, phylogenetic analysis was conducted based on 77 protein-coding genes from 33 taxa and the result may contribute to a better understanding of the evolution progress of the genus Ipomoea (L.), including phylogenetic relationships, intraspecific differentiation and interspecific introgression. PMID:25874767

  6. Light-Induced Chloroplast Shrinkage in vivo Detectable After Rapid Isolation of Chloroplasts From Pisum sativum 1

    PubMed Central

    Nobel, Park S.

    1968-01-01

    A light-induced shrinkage of chloroplasts in vivo could be detected with chloroplasts isolated within 2 minutes of harvesting pea plants. As determined both by packed volume and Coulter counter, the mean volume of chloroplasts from plants in the dark was 39 μ3, whereas it was 31 μ3 for chloroplasts from plants in the light. Upon illumination of the plants, the half-time for the chloroplast shrinkage in vivo was about 3 minutes, and the half-time for the reversal in the dark was about 5 minutes. A plant growth temperature of 20° was optimal for the volume change. The chloroplast shrinkage was half-maximal for a light intensity of 400 lux incident on the plants and was light-saturated near 2000 lux. The light-absorbing pigment responsible for the volume change was chlorophyll. This light-induced shrinkage resulted in a flattening and slight indenting of the chloroplasts. This chloroplast flattening upon illumination of the plants may accompany an increase in the photosynthetic efficiency of chloroplasts. PMID:16656840

  7. The chloroplast RNA helicase ISE2 is required for multiple chloroplast RNA processing steps in Arabidopsis thaliana.

    PubMed

    Bobik, Krzysztof; McCray, Tyra N; Ernest, Ben; Fernandez, Jessica C; Howell, Katharine A; Lane, Thomas; Staton, Margaret; Burch-Smith, Tessa M

    2017-03-27

    INCREASED SIZE EXCLUSION LIMIT2 (ISE2) is a chloroplast-localized RNA helicase that is indispensable for proper plant development. Chloroplasts in leaves with reduced ISE2 expression have previously been shown to exhibit reduced thylakoid contents and increased stromal volume, indicative of defective development. It has recently been reported that ISE2 is required for the splicing of group II introns from chloroplast transcripts. The current study extends these findings, and presents evidence for ISE2's role in multiple aspects of chloroplast RNA processing beyond group II intron splicing. Loss of ISE2 from Arabidopsis thaliana leaves resulted in defects in C-to-U RNA editing, altered accumulation of chloroplast transcripts and chloroplast-encoded proteins, and defective processing of chloroplast ribosomal RNAs. Potential ISE2 substrates were identified by RNA immunoprecipitation followed by next-generation sequencing (RIP-seq), and the diversity of RNA species identified supports ISE2's involvement in multiple aspects of chloroplast RNA metabolism. Comprehensive phylogenetic analyses revealed that ISE2 is a non-canonical Ski2-like RNA helicase that represents a separate sub-clade unique to green photosynthetic organisms, consistent with its function as an essential protein. Thus ISE2's evolutionary conservation may be explained by its numerous roles in regulating chloroplast gene expression. This article is protected by copyright. All rights reserved.

  8. Homologous and heterologous reconstitution of Golgi to chloroplast transport and protein import into the complex chloroplasts of Euglena.

    PubMed

    Sláviková, Silvia; Vacula, Rostislav; Fang, Zhiwei; Ehara, Tomoko; Osafune, Tetsuaki; Schwartzbach, Steven D

    2005-04-15

    Euglena complex chloroplasts evolved through secondary endosymbiosis between a phagotrophic trypanosome host and eukaryotic algal endosymbiont. Cytoplasmically synthesized chloroplast proteins are transported in vesicles as integral membrane proteins from the ER to the Golgi apparatus to the Euglena chloroplast. Euglena chloroplast preprotein pre-sequences contain a functional N-terminal ER-targeting signal peptide and a domain having characteristics of a higher plant chloroplast targeting transit peptide, which contains a hydrophobic stop-transfer membrane anchor sequence that anchors the precursor in the vesicle membrane. Pulse-chase subcellular fractionation studies showed that (35)S-labeled precursor to the light harvesting chlorophyll a/b binding protein accumulated in the Golgi apparatus of Euglena incubated at 15 degrees C and transport to the chloroplast resumed after transfer to 26 degrees C. Transport of the (35)S-labeled precursor to the chlorophyll a/b binding protein from Euglena Golgi membranes to Euglena chloroplasts and import into chloroplasts was reconstituted using Golgi membranes isolated from 15 degrees C cells returned to 26 degrees C. Transport was dependent upon extra- and intrachloroplast ATP and GTP hydrolysis. Golgi to chloroplast transport was not inhibited by N-ethylmaleimide indicating that fusion of Golgi vesicles to the chloroplast envelope does not require N-ethylmaleimide-sensitive factor (NSF). This suggests that N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) are not utilized in the targeting fusion reaction. The Euglena precursor to the chloroplast-localized small subunit of ribulose-1,5-bisphosphate carboxylase was not imported into isolated pea chloroplasts. A precursor with the N-terminal signal peptide deleted was imported, indicating that the Euglena pre-sequence has a transit peptide that functions in pea chloroplasts. A precursor to the small subunit of ribulose-1,5-bisphosphate carboxylase with

  9. Invasive Chloroplast Population Genetics of Mikania micrantha in China: No Local Adaptation and Negative Correlation between Diversity and Geographic Distance

    PubMed Central

    Wang, Ting; Wang, Zhen; Chen, Guopei; Wang, Chunbo; Su, Yingjuan

    2016-01-01

    Two fundamental questions on how invasive species are able to rapidly colonize novel habitat have emerged. One asks whether a negative correlation exists between the genetic diversity of invasive populations and their geographic distance from the origin of introduction. The other is whether selection on the chloroplast genome is important driver of adaptation to novel soil environments. Here, we addressed these questions in a study of the noxious invasive weed, Mikania micrantha, which has rapidly expanded in to southern China after being introduced to Hong Kong in 1884. Seven chloroplast simple sequence repeats (cpSSRs) were used to investigate population genetics in 28 populations of M. micrantha, which produced 39 loci. The soil compositions for these populations, including Mg abundance, were measured. The results showed that M. micrantha possessed relatively high cpSSR variation and differentiation among populations. Multiple diversity indices were quantified, and none was significantly correlated with distance from the origin of introduction. No evidence for “isolation by distance,” significant spatial structure, bottlenecks, nor linkage disequilibrium was detected. We also were unable to identify loci on the chloroplast genome that exhibited patterns of differentiation that would suggest adaptive evolution in response to soil attributes. Soil Mg had only a genome-wide effect instead of being a selective factor, which highlighted the association between Mg and the successful invasion. This study characterizes the role of the chloroplast genome of M. micrantha during its recent invasion of southern China. PMID:27708663

  10. Invasive Chloroplast Population Genetics of Mikania micrantha in China: No Local Adaptation and Negative Correlation between Diversity and Geographic Distance.

    PubMed

    Wang, Ting; Wang, Zhen; Chen, Guopei; Wang, Chunbo; Su, Yingjuan

    2016-01-01

    Two fundamental questions on how invasive species are able to rapidly colonize novel habitat have emerged. One asks whether a negative correlation exists between the genetic diversity of invasive populations and their geographic distance from the origin of introduction. The other is whether selection on the chloroplast genome is important driver of adaptation to novel soil environments. Here, we addressed these questions in a study of the noxious invasive weed, Mikania micrantha, which has rapidly expanded in to southern China after being introduced to Hong Kong in 1884. Seven chloroplast simple sequence repeats (cpSSRs) were used to investigate population genetics in 28 populations of M. micrantha, which produced 39 loci. The soil compositions for these populations, including Mg abundance, were measured. The results showed that M. micrantha possessed relatively high cpSSR variation and differentiation among populations. Multiple diversity indices were quantified, and none was significantly correlated with distance from the origin of introduction. No evidence for "isolation by distance," significant spatial structure, bottlenecks, nor linkage disequilibrium was detected. We also were unable to identify loci on the chloroplast genome that exhibited patterns of differentiation that would suggest adaptive evolution in response to soil attributes. Soil Mg had only a genome-wide effect instead of being a selective factor, which highlighted the association between Mg and the successful invasion. This study characterizes the role of the chloroplast genome of M. micrantha during its recent invasion of southern China.

  11. Light Deprivation-Induced Inhibition of Chloroplast Biogenesis Does Not Arrest Embryo Morphogenesis But Strongly Reduces the Accumulation of Storage Reserves during Embryo Maturation in Arabidopsis.

    PubMed

    Liu, Huichao; Wang, Xiaoxia; Ren, Kaixuan; Li, Kai; Wei, Mengmeng; Wang, Wenjie; Sheng, Xianyong

    2017-01-01

    The chloroplast is one of the most important organelles found exclusively in plant and algal cells. Previous reports indicated that the chloroplast is involved in plant embryogenesis, but the role of the organelle during embryo morphogenesis and maturation is still a controversial question demanding further research. In the present study, siliques of Arabidopsis at the early globular stage were enwrapped using tinfoil, and light deprivation-induced inhibition of the chloroplast biogenesis were validated by stereomicroscope, laser scanning confocal microscope and transmission electron microscope. Besides, the effects of inhibited chloroplast differentiation on embryogenesis, especially on the reserve deposition were analyzed using periodic acid-Schiff reaction, Nile red labeling, and Coomassie brilliant blue staining. Our results indicated that tinfoil enwrapping strongly inhibited the formation of chloroplasts, which did not arrest embryo morphogenesis, but markedly influenced embryo maturation, mainly through reducing the accumulation of storage reserves, especially starch grains and oil. Our data provide a new insight into the roles of the chloroplast during embryogenesis.

  12. Light Deprivation-Induced Inhibition of Chloroplast Biogenesis Does Not Arrest Embryo Morphogenesis But Strongly Reduces the Accumulation of Storage Reserves during Embryo Maturation in Arabidopsis

    PubMed Central

    Liu, Huichao; Wang, Xiaoxia; Ren, Kaixuan; Li, Kai; Wei, Mengmeng; Wang, Wenjie; Sheng, Xianyong

    2017-01-01

    The chloroplast is one of the most important organelles found exclusively in plant and algal cells. Previous reports indicated that the chloroplast is involved in plant embryogenesis, but the role of the organelle during embryo morphogenesis and maturation is still a controversial question demanding further research. In the present study, siliques of Arabidopsis at the early globular stage were enwrapped using tinfoil, and light deprivation-induced inhibition of the chloroplast biogenesis were validated by stereomicroscope, laser scanning confocal microscope and transmission electron microscope. Besides, the effects of inhibited chloroplast differentiation on embryogenesis, especially on the reserve deposition were analyzed using periodic acid-Schiff reaction, Nile red labeling, and Coomassie brilliant blue staining. Our results indicated that tinfoil enwrapping strongly inhibited the formation of chloroplasts, which did not arrest embryo morphogenesis, but markedly influenced embryo maturation, mainly through reducing the accumulation of storage reserves, especially starch grains and oil. Our data provide a new insight into the roles of the chloroplast during embryogenesis. PMID:28775734

  13. CLUMPED CHLOROPLASTS 1 is required for plastid separation in Arabidopsis

    PubMed Central

    Yang, Yue; Sage, Tammy L.; Liu, Yi; Ahmad, Tiara R.; Marshall, Wallace F.; Shiu, Shin-Han; Froehlich, John E.; Imre, Kathleen M.; Osteryoung, Katherine W.

    2011-01-01

    We identified an Arabidopsis thaliana mutant, clumped chloroplasts 1 (clmp1), in which disruption of a gene of unknown function causes chloroplasts to cluster instead of being distributed throughout the cytoplasm. The phenotype affects chloroplasts and nongreen plastids in multiple organs and cell types, but is detectable only at certain developmental stages. In young leaf petioles of clmp1, where clustering is prevalent, cells lacking chloroplasts are detected, suggesting impaired chloroplast partitioning during mitosis. Although organelle distribution and partitioning are actin-dependent in plants, the actin cytoskeleton in clmp1 is indistinguishable from that in WT, and peroxisomes and mitochondria are distributed normally. A CLMP1-YFP fusion protein that complements clmp1 localizes to discrete foci in the cytoplasm, most of which colocalize with the cell periphery or with chloroplasts. Ultrastructural analysis revealed that chloroplasts within clmp1 clusters are held together by membranous connections, including thin isthmi characteristic of late-stage chloroplast division. This finding suggests that constriction of dividing chloroplasts proceeds normally in clmp1, but separation is impaired. Consistently, chloroplast size and number, as well as positioning of the plastid division proteins FtsZ and ARC5/DRP5B, are unaffected in clmp1, indicating that loss of CLMP1-mediated chloroplast separation does not prevent otherwise normal division. CLMP1-like sequences are unique to green algae and land plants, and the CLMP1 sequence suggests that it functions through protein–protein interactions. Our studies identify a unique class of proteins required for plastid separation after the constriction stage of plastid division and indicate that CLMP1 activity is also required for plastid distribution and partitioning during cell division. PMID:22025705

  14. CLUMPED CHLOROPLASTS 1 is required for plastid separation in Arabidopsis.

    PubMed

    Yang, Yue; Sage, Tammy L; Liu, Yi; Ahmad, Tiara R; Marshall, Wallace F; Shiu, Shin-Han; Froehlich, John E; Imre, Kathleen M; Osteryoung, Katherine W

    2011-11-08

    We identified an Arabidopsis thaliana mutant, clumped chloroplasts 1 (clmp1), in which disruption of a gene of unknown function causes chloroplasts to cluster instead of being distributed throughout the cytoplasm. The phenotype affects chloroplasts and nongreen plastids in multiple organs and cell types, but is detectable only at certain developmental stages. In young leaf petioles of clmp1, where clustering is prevalent, cells lacking chloroplasts are detected, suggesting impaired chloroplast partitioning during mitosis. Although organelle distribution and partitioning are actin-dependent in plants, the actin cytoskeleton in clmp1 is indistinguishable from that in WT, and peroxisomes and mitochondria are distributed normally. A CLMP1-YFP fusion protein that complements clmp1 localizes to discrete foci in the cytoplasm, most of which colocalize with the cell periphery or with chloroplasts. Ultrastructural analysis revealed that chloroplasts within clmp1 clusters are held together by membranous connections, including thin isthmi characteristic of late-stage chloroplast division. This finding suggests that constriction of dividing chloroplasts proceeds normally in clmp1, but separation is impaired. Consistently, chloroplast size and number, as well as positioning of the plastid division proteins FtsZ and ARC5/DRP5B, are unaffected in clmp1, indicating that loss of CLMP1-mediated chloroplast separation does not prevent otherwise normal division. CLMP1-like sequences are unique to green algae and land plants, and the CLMP1 sequence suggests that it functions through protein-protein interactions. Our studies identify a unique class of proteins required for plastid separation after the constriction stage of plastid division and indicate that CLMP1 activity is also required for plastid distribution and partitioning during cell division.

  15. Control of starch granule numbers in Arabidopsis chloroplasts.

    PubMed

    Crumpton-Taylor, Matilda; Grandison, Scott; Png, Kenneth M Y; Bushby, Andrew J; Smith, Alison M

    2012-02-01

    The aim of this work was to investigate starch granule numbers in Arabidopsis (Arabidopsis thaliana) leaves. Lack of quantitative information on the extent of genetic, temporal, developmental, and environmental variation in granule numbers is an important limitation in understanding control of starch degradation and the mechanism of granule initiation. Two methods were developed for reliable estimation of numbers of granules per chloroplast. First, direct measurements were made on large series of consecutive sections of mesophyll tissue obtained by focused ion beam-scanning electron microscopy. Second, average numbers were calculated from the starch contents of leaves and chloroplasts and estimates of granule mass based on granule dimensions. Examination of wild-type plants and accumulation and regulation of chloroplast (arc) mutants with few, large chloroplasts provided the following new insights. There is wide variation in chloroplast volumes in cells of wild-type leaves. Granule numbers per chloroplast are correlated with chloroplast volume, i.e. large chloroplasts have more granules than small chloroplasts. Mature leaves of wild-type plants and arc mutants have approximately the same number of granules per unit volume of stroma, regardless of the size and number of chloroplasts per cell. Granule numbers per unit volume of stroma are also relatively constant in immature leaves but are greater than in mature leaves. Granule initiation occurs as chloroplasts divide in immature leaves, but relatively little initiation occurs in mature leaves. Changes in leaf starch content over the diurnal cycle are largely brought about by changes in the volume of a fixed number of granules.

  16. Some Properties of the Chloroplast Envelope as Revealed by Electrophoretic Mobility Studies of Intact Chloroplasts 1

    PubMed Central

    Stocking, C. Ralph; Franceschi, Vincent R.

    1982-01-01

    The electrophoretic mobility of mature spinach (Spinacia oleracea L. var. Americana) chloroplasts sampled over a 7-month period was between −2.03 and −2.45 micrometers per second per volt per centimeter when suspended in a solution containing 1 millimolar CaCl2. The surface charge density of EDTA-treated chloroplasts was calculated to be −7,400 electrostatic units per square centimeter representing, on the average, one electronic charge per 645 square Angstroms. Electrophoretic mobility increases during plastid maturation. Calcium, but not magnesium, generally stabilized the envelope of isolated plastids against small increases in surface charge that occur with time in the absence of calcium. Pronase caused a sharp, but temporary, decrease in the electrophoretic mobility of chloroplasts. This was interpreted as representing a transient binding of pronase to the envelope surface during proteolysis. No −SH groups were detected on the surface of the plastid envelope. Inasmuch as the isoelectric point of intact chloroplasts was found to be at pH 4.5, it is likely that the major part of the total surface charge results from the presence of exposed carboxyl groups of intrinsic envelope proteins that are not readily hydrolyzed by mild pronase treatment. PMID:16662663

  17. Arabidopsis thaliana leaves with altered chloroplast numbers and chloroplast movement exhibit impaired adjustments to both low and high light.

    PubMed

    Königer, Martina; Delamaide, Joy A; Marlow, Elizabeth D; Harris, Gary C

    2008-01-01

    The effects of chloroplast number and size on the capacity for blue light-dependent chloroplast movement, the ability to increase light absorption under low light, and the susceptibility to photoinhibition were investigated in Arabidopsis thaliana. Leaves of wild-type and chloroplast number mutants with mean chloroplast numbers ranging from 120 to two per mesophyll cell were analysed. Chloroplast movement was monitored as changes in light transmission through the leaves. Light transmission was used as an indicator of the ability of leaves to optimize light absorption. The ability of leaves to deal with 3 h of high light stress at 10 degrees C and their capacity to recover in low light was determined by measuring photochemical efficiencies of PSII using chlorophyll a fluorescence. Chloroplast movement was comparable in leaves ranging in chloroplast numbers from 120 to 30 per mesophyll cell: the final light transmission levels after exposure to 0.1 (accumulation response) and 100 micromol photons m(-2) s(-1) (avoidance response) were indistinguishable, the chloroplasts responded quickly to small increases in light intensity and the kinetics of movement were similar. However, when chloroplast numbers per mesophyll cell decreased to 18 or below, the accumulation response was significantly reduced. The avoidance response was only impaired in mutants with nine or fewer chloroplasts, both in terms of final transmission levels and the speed of movement. Only mutants lacking both blue light receptors (phot1/phot2) or those with drastically reduced chloroplast numbers and severely impacted avoidance responses showed a reduced ability to recover from high light stress.

  18. Why have chloroplasts developed a unique motility system?

    PubMed

    Suetsugu, Noriyuki; Dolja, Valerian V; Wada, Masamitsu

    2010-10-01

    Organelle movement in plants is dependent on actin filaments with most of the organelles being transported along the actin cables by class XI myosins. Although chloroplast movement is also actin filament-dependent, a potential role of myosin motors in this process is poorly understood. Interestingly, chloroplasts can move in any direction, and change the direction within short time periods, suggesting that chloroplasts use the newly formed actin filaments rather than preexisting actin cables. Furthermore, the data on myosin gene knockouts and knockdowns in Arabidopsis and tobacco do not support myosins' XI role in chloroplast movement. Our recent studies revealed that chloroplast movement and positioning are mediated by the short actin filaments localized at chloroplast periphery (cp-actin filaments) rather than cytoplasmic actin cables. The accumulation of cp-actin filaments depends on kinesin-like proteins, KAC1 and KAC2, as well as on a chloroplast outer membrane protein CHUP1. We propose that plants evolved a myosin XI-independent mechanism of the actin-based chloroplast movement that is distinct from the mechanism used by other organelles.

  19. The complete chloroplast genome of common walnut (Juglans regia)

    Treesearch

    Yiheng ​Hu; Keith E. Woeste; Meng Dang; Tao Zhou; Xiaojia Feng; Guifang Zhao; Zhanlin Liu; Zhonghu Li; Peng. Zhao

    2016-01-01

    Common walnut (Juglans regia L.) is cultivated in temperate regions worldwide for its wood and nuts. The complete chloroplast genome of J. regia was sequenced using the Illumina MiSeq platform. This is the first complete chloroplast sequence for the Juglandaceae, a family that includes numerous species of economic importance....

  20. Chloroplast Proteases: Updates on Proteolysis within and across Suborganellar Compartments.

    PubMed

    Nishimura, Kenji; Kato, Yusuke; Sakamoto, Wataru

    2016-08-01

    Chloroplasts originated from the endosymbiosis of ancestral cyanobacteria and maintain transcription and translation machineries for around 100 proteins. Most endosymbiont genes, however, have been transferred to the host nucleus, and the majority of the chloroplast proteome is composed of nucleus-encoded proteins that are biosynthesized in the cytosol and then imported into chloroplasts. How chloroplasts and the nucleus communicate to control the plastid proteome remains an important question. Protein-degrading machineries play key roles in chloroplast proteome biogenesis, remodeling, and maintenance. Research in the past few decades has revealed more than 20 chloroplast proteases, which are localized to specific suborganellar locations. In particular, two energy-dependent processive proteases of bacterial origin, Clp and FtsH, are central to protein homeostasis. Processing endopeptidases such as stromal processing peptidase and thylakoidal processing peptidase are involved in the maturation of precursor proteins imported into chloroplasts by cleaving off the amino-terminal transit peptides. Presequence peptidases and organellar oligopeptidase subsequently degrade the cleaved targeting peptides. Recent findings have indicated that not only intraplastidic but also extraplastidic processive protein-degrading systems participate in the regulation and quality control of protein translocation across the envelopes. In this review, we summarize current knowledge of the major chloroplast proteases in terms of type, suborganellar localization, and diversification. We present details of these degradation processes as case studies according to suborganellar compartment (envelope, stroma, and thylakoids). Key questions and future directions in this field are discussed. © 2016 American Society of Plant Biologists. All Rights Reserved.

  1. Processing peptidases in mitochondria and chloroplasts.

    PubMed

    Teixeira, Pedro Filipe; Glaser, Elzbieta

    2013-02-01

    Most of the mitochondrial and chloroplastic proteins are nuclear encoded and synthesized in the cytosol as precursor proteins with N-terminal extensions called targeting peptides. Targeting peptides function as organellar import signals, they are recognized by the import receptors and route precursors through the protein translocons across the organellar membranes. After the fulfilled function, targeting peptides are proteolytically cleaved off inside the organelles by different processing peptidases. The processing of mitochondrial precursors is catalyzed in the matrix by the Mitochondrial Processing Peptidase, MPP, the Mitochondrial Intermediate Peptidase, MIP (recently called Octapeptidyl aminopeptidase 1, Oct1) and the Intermediate cleaving peptidase of 55kDa, Icp55. Furthermore, different inner membrane peptidases (Inner Membrane Proteases, IMPs, Atp23, rhomboids and AAA proteases) catalyze additional processing functions, resulting in intra-mitochondrial sorting of proteins, the targeting to the intermembrane space or in the assembly of proteins into inner membrane complexes. Chloroplast targeting peptides are cleaved off in the stroma by the Stromal Processing Peptidase, SPP. If the protein is further translocated to the thylakoid lumen, an additional thylakoid-transfer sequence is removed by the Thylakoidal Processing Peptidase, TPP. Proper function of the D1 protein of Photosystem II reaction center requires its C-terminal processing by Carboxy-terminal processing protease, CtpA. Both in mitochondria and in chloroplasts, the cleaved targeting peptides are finally degraded by the Presequence Protease, PreP. The organellar proteases involved in precursor processing and targeting peptide degradation constitute themselves a quality control system ensuring the correct maturation and localization of proteins as well as assembly of protein complexes, contributing to sustenance of organelle functions. Dysfunctions of several mitochondrial processing proteases have

  2. Expression of eukaryotic polypeptides in chloroplasts

    SciTech Connect

    Mayfield, Stephen P.

    2013-06-04

    The present invention relates to a gene expression system in eukaryotic and prokaryotic cells, preferably plant cells and intact plants. In particular, the invention relates to an expression system having a RB47 binding site upstream of a translation initiation site for regulation of translation mediated by binding of RB47 protein, a member of the poly(A) binding protein family. Regulation is further effected by RB60, a protein disulfide isomerase. The expression system is capable of functioning in the nuclear/cytoplasm of cells and in the chloroplast of plants. Translation regulation of a desired molecule is enhanced approximately 100 fold over that obtained without RB47 binding site activation.

  3. Expression of eukaryotic polypeptides in chloroplasts

    DOEpatents

    Mayfield, Stephen P

    2013-06-04

    The present invention relates to a gene expression system in eukaryotic and prokaryotic cells, preferably plant cells and intact plants. In particular, the invention relates to an expression system having a RB47 binding site upstream of a translation initiation site for regulation of translation mediated by binding of RB47 protein, a member of the poly(A) binding protein family. Regulation is further effected by RB60, a protein disulfide isomerase. The expression system is capable of functioning in the nuclear/cytoplasm of cells and in the chloroplast of plants. Translation regulation of a desired molecule is enhanced approximately 100 fold over that obtained without RB47 binding site activation.

  4. Noncoding chloroplast DNA variation in Mexican pines.

    PubMed

    Perez de la Rosa, J; Harris, S A; Farjon, A

    1995-11-01

    Universal primers were used for PCR amplification of three noncoding regions of chloroplast DNA in order to study restriction site variation in 12 Mexican pine species. Two length mutations were identified that are of diagnostic value for two subgenera or sections of the genus. Phylogenetic analysis of the restriction site and length variation showed patterns of variation largely consistent with previous arrangements of these pines, except for the position of Pinus nelsonii, indicating that Pinus section Parraya Mayr, as circumscribed by Little and Critchfield (1969) and later authors, is not a monophyletic group.

  5. Membrane heredity and early chloroplast evolution.

    PubMed

    Cavalier-Smith, T

    2000-04-01

    Membrane heredity was central to the unique symbiogenetic origin from cyanobacteria of chloroplasts in the ancestor of Plantae (green plants, red algae, glaucophytes) and to subsequent lateral transfers of plastids to form even more complex photosynthetic chimeras. Each symbiogenesis integrated disparate genomes and several radically different genetic membranes into a more complex cell. The common ancestor of Plantae evolved transit machinery for plastid protein import. In later secondary symbiogeneses, signal sequences were added to target proteins across host perialgal membranes: independently into green algal plastids (euglenoids, chlorarachneans) and red algal plastids (alveolates, chromists). Conservatism and innovation during early plastid diversification are discussed.

  6. Regulation of Chloroplastic Carbonic Anhydrase 1

    PubMed Central

    Porter, Michael A.; Grodzinski, Bernard

    1983-01-01

    It was previously reported that magnesium ion inhibited carbonic anhydrase (Bamberger and Avron 1975 Plant Physiol 56: 481-485). Studies with partially purified carbonic anhydrase from spinach (Spinacia oleracea L.) chloroplasts show that the effect was the result of the chloride counterion and not the magnesium ion. Enzyme activity was reduced 50% upon addition of 3 to 10 millimolar MgCl2 or KCl while all additions of MgSO4 between 0.3 and 10 millimolar were mildly stimulatory. PMID:16663052

  7. Non-contact intracellular binding of chloroplasts in vivo

    PubMed Central

    Li, Yuchao; Xin, Hongbao; Liu, Xiaoshuai; Li, Baojun

    2015-01-01

    Non-contact intracellular binding and controllable manipulation of chloroplasts in vivo was demonstrated using an optical fiber probe. Launching a 980-nm laser beam into a fiber, which was placed about 3 μm above the surface of a living plant (Hydrilla verticillata) leaf, enabled stable binding of different numbers of chloroplasts, as well as their arrangement into one-dimensional chains and two-dimensional arrays inside the leaf without damaging the chloroplasts. Additionally, the formed chloroplast chains were controllably transported inside the living cells. The optical force exerted on the chloroplasts was calculated to explain the experimental results. This method provides a flexible method for studying intracellular organelle interaction with highly organized organelle-organelle contact in vivo in a non-contact manner. PMID:26043396

  8. The complete chloroplast genome of the Dendrobium strongylanthum (Orchidaceae: Epidendroideae).

    PubMed

    Li, Jing; Chen, Chen; Wang, Zhe-Zhi

    2016-07-01

    Complete chloroplast genome sequence is very useful for studying the phylogenetic and evolution of species. In this study, the complete chloroplast genome of Dendrobium strongylanthum was constructed from whole-genome Illumina sequencing data. The chloroplast genome is 153 058 bp in length with 37.6% GC content and consists of two inverted repeats (IRs) of 26 316 bp. The IR regions are separated by large single-copy region (LSC, 85 836 bp) and small single-copy (SSC, 14 590 bp) region. A total of 130 chloroplast genes were successfully annotated, including 84 protein coding genes, 38 tRNA genes, and eight rRNA genes. Phylogenetic analyses showed that the chloroplast genome of Dendrobium strongylanthum is related to that of the Dendrobium officinal.

  9. Licensed to Kill: Mitochondria, Chloroplasts, and Cell Death.

    PubMed

    Van Aken, Olivier; Van Breusegem, Frank

    2015-11-01

    Programmed cell death (PCD) is crucial in plant organogenesis and survival. In this review the involvement of mitochondria and chloroplasts in PCD execution is critically assessed. Recent findings support a central role for mitochondria in PCD, with newly identified components of the mitochondrial electron transport chain (mETC), FOF1 ATP synthase, cardiolipins, and ATPase AtOM66. While chloroplasts received less attention, their contribution to PCD is well supported, suggesting that they possibly contribute by producing reactive oxygen species (ROS) in the presence of light or even contribute through cytochrome f release. Finally we discuss two working models where mitochondria and chloroplasts could cooperatively execute PCD: mitochondria initiate the commitment steps and recruit chloroplasts for swift execution or, alternatively, mitochondria and chloroplasts could operate in parallel. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Non-contact intracellular binding of chloroplasts in vivo.

    PubMed

    Li, Yuchao; Xin, Hongbao; Liu, Xiaoshuai; Li, Baojun

    2015-06-04

    Non-contact intracellular binding and controllable manipulation of chloroplasts in vivo was demonstrated using an optical fiber probe. Launching a 980-nm laser beam into a fiber, which was placed about 3 μm above the surface of a living plant (Hydrilla verticillata) leaf, enabled stable binding of different numbers of chloroplasts, as well as their arrangement into one-dimensional chains and two-dimensional arrays inside the leaf without damaging the chloroplasts. Additionally, the formed chloroplast chains were controllably transported inside the living cells. The optical force exerted on the chloroplasts was calculated to explain the experimental results. This method provides a flexible method for studying intracellular organelle interaction with highly organized organelle-organelle contact in vivo in a non-contact manner.

  11. Non-contact intracellular binding of chloroplasts in vivo

    NASA Astrophysics Data System (ADS)

    Li, Yuchao; Xin, Hongbao; Liu, Xiaoshuai; Li, Baojun

    2015-06-01

    Non-contact intracellular binding and controllable manipulation of chloroplasts in vivo was demonstrated using an optical fiber probe. Launching a 980-nm laser beam into a fiber, which was placed about 3 μm above the surface of a living plant (Hydrilla verticillata) leaf, enabled stable binding of different numbers of chloroplasts, as well as their arrangement into one-dimensional chains and two-dimensional arrays inside the leaf without damaging the chloroplasts. Additionally, the formed chloroplast chains were controllably transported inside the living cells. The optical force exerted on the chloroplasts was calculated to explain the experimental results. This method provides a flexible method for studying intracellular organelle interaction with highly organized organelle-organelle contact in vivo in a non-contact manner.

  12. Comparative proteomic analysis of amaranth mesophyll and bundle sheath chloroplasts and their adaptation to salt stress.

    PubMed

    Joaquín-Ramos, Ahuitzolt; Huerta-Ocampo, José Á; Barrera-Pacheco, Alberto; De León-Rodríguez, Antonio; Baginsky, Sacha; Barba de la Rosa, Ana P

    2014-09-15

    The effect of salt stress was analyzed in chloroplasts of Amaranthus cruentus var. Amaranteca, a plant NAD-malic enzyme (NAD-ME) type. Morphology of chloroplasts from bundle sheath (BSC) and mesophyll (MC) was observed by transmission electron microscopy (TEM). BSC and MC from control plants showed similar morphology, however under stress, changes in BSC were observed. The presence of ribulose bisphosphate carboxylase/oxygenase (RuBisCO) was confirmed by immunohistochemical staining in both types of chloroplasts. Proteomic profiles of thylakoid protein complexes from BSC and MC, and their changes induced by salt stress were analyzed by blue-native polyacrylamide gel electrophoresis followed by SDS-PAGE (2-D BN/SDS-PAGE). Differentially accumulated protein spots were analyzed by LC-MS/MS. Although A. cruentus photosynthetic tissue showed the Kranz anatomy, the thylakoid proteins showed some differences at photosystem structure level. Our results suggest that A. cruentus var. Amaranteca could be better classified as a C3-C4 photosynthetic plant. Copyright © 2014 Elsevier GmbH. All rights reserved.

  13. Application of a simplified method of chloroplast enrichment to small amounts of tissue for chloroplast genome sequencing1

    PubMed Central

    Sakaguchi, Shota; Ueno, Saneyoshi; Tsumura, Yoshihiko; Setoguchi, Hiroaki; Ito, Motomi; Hattori, Chie; Nozoe, Shogo; Takahashi, Daiki; Nakamasu, Riku; Sakagami, Taishi; Lannuzel, Guillaume; Fogliani, Bruno; Wulff, Adrien S.; L’Huillier, Laurent; Isagi, Yuji

    2017-01-01

    Premise of the study: High-throughput sequencing of genomic DNA can recover complete chloroplast genome sequences, but the sequence data are usually dominated by sequences from nuclear/mitochondrial genomes. To overcome this deficiency, a simple enrichment method for chloroplast DNA from small amounts of plant tissue was tested for eight plant species including a gymnosperm and various angiosperms. Methods: Chloroplasts were enriched using a high-salt isolation buffer without any step gradient procedures, and enriched chloroplast DNA was sequenced by multiplexed high-throughput sequencing. Results: Using this simple method, significant enrichment of chloroplast DNA-derived reads was attained, allowing deep sequencing of chloroplast genomes. As an example, the chloroplast genome of the conifer Callitris sulcata was assembled, from which polymorphic microsatellite loci were isolated successfully. Discussion: This chloroplast enrichment method from small amounts of plant tissue will be particularly useful for studies that use sequencers with relatively small throughput and that cannot use large amounts of tissue (e.g., for endangered species). PMID:28529832

  14. Chloroplast targeting of FtsHprotease is essential for chloroplast development and thylakoid stability at elevated temperatures in plants

    USDA-ARS?s Scientific Manuscript database

    AtFtsH11 is a chloroplast and mitochondria dual targeted metalloprotease, identified as essential for Arabidopsis plant to survive at moderate high temperatures at all developmental stages. Our study showed that FtsH11 plays critical roles in both the early stages of chloroplast biogenesis and main...

  15. The Chloroplast Genome of Pellia endiviifolia: Gene Content, RNA-Editing Pattern, and the Origin of Chloroplast Editing

    PubMed Central

    Grosche, Christopher; Funk, Helena T.; Maier, Uwe G.; Zauner, Stefan

    2012-01-01

    RNA editing is a post-transcriptional process that can act upon transcripts from mitochondrial, nuclear, and chloroplast genomes. In chloroplasts, single-nucleotide conversions in mRNAs via RNA editing occur at different frequencies across the plant kingdom. These range from several hundred edited sites in some mosses and ferns to lower frequencies in seed plants and the complete lack of RNA editing in the liverwort Marchantia polymorpha. Here, we report the sequence and edited sites of the chloroplast genome from the liverwort Pellia endiviifolia. The type and frequency of chloroplast RNA editing display a pattern highly similar to that in seed plants. Analyses of the C to U conversions and the genomic context in which the editing sites are embedded provide evidence in favor of the hypothesis that chloroplast RNA editing evolved to compensate mutations in the first land plants. PMID:23221608

  16. The chloroplast genome of Pellia endiviifolia: gene content, RNA-editing pattern, and the origin of chloroplast editing.

    PubMed

    Grosche, Christopher; Funk, Helena T; Maier, Uwe G; Zauner, Stefan

    2012-01-01

    RNA editing is a post-transcriptional process that can act upon transcripts from mitochondrial, nuclear, and chloroplast genomes. In chloroplasts, single-nucleotide conversions in mRNAs via RNA editing occur at different frequencies across the plant kingdom. These range from several hundred edited sites in some mosses and ferns to lower frequencies in seed plants and the complete lack of RNA editing in the liverwort Marchantia polymorpha. Here, we report the sequence and edited sites of the chloroplast genome from the liverwort Pellia endiviifolia. The type and frequency of chloroplast RNA editing display a pattern highly similar to that in seed plants. Analyses of the C to U conversions and the genomic context in which the editing sites are embedded provide evidence in favor of the hypothesis that chloroplast RNA editing evolved to compensate mutations in the first land plants.

  17. (Calcium gating of proton fluxes in chloroplasts)

    SciTech Connect

    Dilley, R.A.

    1991-01-01

    Work supported by this grant has been aimed at better understanding the still-mysterious phenomenon of sequestered proton gradients which strong evidence suggests can energize ATP formation in chloroplast organelle membranes. Results from several laboratories support the notion that chloroplasts can couple the energy of H{sup +} gradients. Research in may lab has, since 1983, been deeply involved in a two-pronged approach, (A) identifying and quantitating sequestered proton buffering groups and (B) trying to elucidate just how the sequestered H{sup +} gradient is maintained and what regulates the switching between the localized and delocalized coupling modes. One aspect we have worked on under DOE auspices is the question whether the localized H{sup +} coupling, routinely detected in my lab by a protocol which measures the number of single-turnover flashes (usually fired at 5 Hz) required to reach the energization threshold for ATP formation, can continue in steady illumination. It is possible to consider that a localized coupling response could be observed in the initial energization transient followed obligatorily by the sustained H{sup +} gradient equilibrating with the lumen bulk phase. If that occurred, it would have very important ramifications as to how one evaluates the possible physiological meaning of localized'' coupling. To test this, we developed a steady illumination protocol which is briefly discussed.

  18. Complete sequence of Euglena gracilis chloroplast DNA.

    PubMed Central

    Hallick, R B; Hong, L; Drager, R G; Favreau, M R; Monfort, A; Orsat, B; Spielmann, A; Stutz, E

    1993-01-01

    We report the complete DNA sequence of the Euglena gracilis, Pringsheim strain Z chloroplast genome. This circular DNA is 143,170 bp, counting only one copy of a 54 bp tandem repeat sequence that is present in variable copy number within a single culture. The overall organization of the genome involves a tandem array of three complete and one partial ribosomal RNA operons, and a large single copy region. There are genes for the 16S, 5S, and 23S rRNAs of the 70S chloroplast ribosomes, 27 different tRNA species, 21 ribosomal proteins plus the gene for elongation factor EF-Tu, three RNA polymerase subunits, and 27 known photosynthesis-related polypeptides. Several putative genes of unknown function have also been identified, including five within large introns, and five with amino acid sequence similarity to genes in other organisms. This genome contains at least 149 introns. There are 72 individual group II introns, 46 individual group III introns, 10 group II introns and 18 group III introns that are components of twintrons (introns-within-introns), and three additional introns suspected to be twintrons composed of multiple group II and/or group III introns, but not yet characterized. At least 54,804 bp, or 38.3% of the total DNA content is represented by introns. PMID:8346031

  19. Ferredoxin-linked chloroplast enzymes. Progress report

    SciTech Connect

    1993-12-31

    This report summarizes research on ferredoxin:NADP{sup +} oxidoreductase and ferredoxin:thioredoxin reductase. One of the primary goals of the original proposal was to map the ferredoxin-binding sites on three soluble enzymes that are located in spinach chloroplasts and utilize ferredoxin as an electron donor:Ferredoxin:NADP{sup +} oxidoreductase (FNR); ferredoxin:thioredoxin reductase (FTR) and glutamate synthase. As the availability of amino acid sequences for the enzymes are important in such studies, it was proposed that the amino acid sequence of glutamate synthase be determined. The amino acid sequences of FNR, FTR and ferredoxin are already known. An aim related to elucidating the binding sites on these enzymes for ferredoxin was to determine whether there is a common site on ferredoxin involved in binding to all of these ferredoxin-dependent chloroplast enzymes and, if so, to map it. One additional aim was to characterize thioredoxin binding by FTR and determine whether the same site on FTR is involved in binding both ferredoxin and thioredoxin. Considerable progress has been made on most of these original projects, although work conducted on FTR is still in its preliminary stages.

  20. Arginine Decarboxylase Is Localized in Chloroplasts.

    PubMed Central

    Borrell, A.; Culianez-Macia, F. A.; Altabella, T.; Besford, R. T.; Flores, D.; Tiburcio, A. F.

    1995-01-01

    Plants, unlike animals, can use either ornithine decarboxylase or arginine decarboxylase (ADC) to produce the polyamine precursor putrescine. Lack of knowledge of the exact cellular and subcellular location of these enzymes has been one of the main obstacles to our understanding of the biological role of polyamines in plants. We have generated polyclonal antibodies to oat (Avena sativa L.) ADC to study the spatial distribution and subcellular localization of ADC protein in different oat tissues. By immunoblotting and immunocytochemistry, we show that ADC is organ specific. By cell fractionation and immunoblotting, we show that ADC is localized in chloroplasts associated with the thylakoid membrane. The results also show that increased levels of ADC protein are correlated with high levels of ADC activity and putrescine in osmotically stressed oat leaves. A model of compartmentalization for the arginine pathway and putrescine biosynthesis in active photosynthetic tissues has been proposed. In the context of endosymbiote-driven metabolic evolution in plants, the location of ADC in the chloroplast compartment may have major evolutionary significance, since it explains (a) why plants can use two alternative pathways for putrescine biosynthesis and (b) why animals do not possess ADC. PMID:12228631

  1. Heteroplasmy of chloroplast DNA in Medicago.

    PubMed

    Johnson, L B; Palmer, J D

    1989-01-01

    Two chloroplast DNA (cpDNA) regions exhibiting a high frequency of intra- or inter-species variation were identified in 12 accessions of the genus Medicago. Restriction maps of both regions were prepared for alfalfa, and the probable nature of the events causing the DNA differences was identified. Specific DNA fragments were then cloned for use in identification of variants in each region. Two each of M. sativa ssp. varia and ssp. caerulea and one of six M. sativa ssp. sativa single plants examined possessed cpDNA heterogeneity as identified by screening extracts for fragments generated by the presence and absence of a specific Xba I restriction site. Three plants of M. sativa ssp. sativa, two of each of sspp. varia and caerulea, and three M. scutellata were also examined for single-plant cpDNA heterogeneity at a hypervariable region where differences resulted from small insertion-deletion events. A single M. scutellata plant with mixed cpDNAs was identified. Sorting out was seen when one spp. sativa plant with mixed plastid types identifiable by the Xba I restriction site difference was vegetatively propagated. This indicated that the initial stock plant was heteroplastidic. Controlled crosses will be required in order to test whether heteroplasmy results from chloroplast transmission in the pollen and to examine the dynamic of sorting out. However, heteroplasmy is apparently not a rare situation in Medicago.

  2. GLK gene pairs regulate chloroplast development in diverse plant species.

    PubMed

    Fitter, David W; Martin, David J; Copley, Martin J; Scotland, Robert W; Langdale, Jane A

    2002-09-01

    Chloroplast biogenesis is a complex process that requires close co-ordination between two genomes. Many of the proteins that accumulate in the chloroplast are encoded by the nuclear genome, and the developmental transition from proplastid to chloroplast is regulated by nuclear genes. Here we show that a pair of Golden 2-like (GLK) genes regulates chloroplast development in Arabidopsis. The GLK proteins are members of the GARP superfamily of transcription factors, and phylogenetic analysis demonstrates that the maize, rice and Arabidopsis GLK gene pairs comprise a distinct group within the GARP superfamily. Further phylogenetic analysis suggests that the gene pairs arose through separate duplication events in the monocot and dicot lineages. As in rice, AtGLK1 and AtGLK2 are expressed in partially overlapping domains in photosynthetic tissue. Insertion mutants demonstrate that this expression pattern reflects a degree of functional redundancy as single mutants display normal phenotypes in most photosynthetic tissues. However, double mutants are pale green in all photosynthetic tissues and chloroplasts exhibit a reduction in granal thylakoids. Products of several genes involved in light harvesting also accumulate at reduced levels in double mutant chloroplasts. GLK genes therefore regulate chloroplast development in diverse plant species.

  3. Global RNA association with the transcriptionally active chromosome of chloroplasts.

    PubMed

    Lehniger, Marie-Kristin; Finster, Sabrina; Melonek, Joanna; Oetke, Svenja; Krupinska, Karin; Schmitz-Linneweber, Christian

    2017-09-08

    Processed chloroplast RNAs are co-enriched with preparations of the chloroplast transcriptionally active chromosome. Chloroplast genomes are organized as a polyploid DNA-protein structure called the nucleoid. Transcriptionally active chloroplast DNA together with tightly bound protein factors can be purified by gel filtration as a functional entity called the transcriptionally active chromosome (TAC). Previous proteomics analyses of nucleoids and of TACs demonstrated a considerable overlap in protein composition including RNA binding proteins. Therefore the RNA content of TAC preparations from Nicotiana tabacum was determined using whole genome tiling arrays. A large number of chloroplast RNAs was found to be associated with the TAC. The pattern of RNAs attached to the TAC consists of RNAs produced by different chloroplast RNA polymerases and differs from the pattern of RNA found in input controls. An analysis of RNA splicing and RNA editing of selected RNA species demonstrated that TAC-associated RNAs are processed to a similar extent as the RNA in input controls. Thus, TAC fractions contain a specific subset of the processed chloroplast transcriptome.

  4. Influence of sugars on blue light-induced chloroplast relocations.

    PubMed

    Banaś, Agnieszka Katarzyna; Gabryś, Halina

    2007-07-01

    The aim of this study was to investigate the influence of sugars on blue light-induced chloroplast movements. Sucrose and glucose inhibited chloroplast responses in the detached leaves of Arabidopsis thaliana and in Lemna trisulca fronds in a concentration and time-dependent manner. The prolonged exposure necessary for inhibition indicates that sugars may act via altered gene expression. Overexpression of phototropin2, a photoreceptor responsible for the strong blue light response of chloroplasts, counteracted the sugar effect. This may suggest that sugars modify some component(s) of the phototropin2-mediated signal transduction pathway. The expression of PHOT2 was not suppressed by sugars in wild type plants, it was even upregulated by glucose. Impaired chloroplast movements were observed only in mature Arabidopsis plants. The mRNA of SAG12, a late senescence marker, was not detectable in the sugar-incubated leaves. The SAG13 mRNA level and its regulation by sugars were similar in wild type and PHOT2 overexpressor. Thus, the sugar insensitivity of 35S:PHOT2 chloroplast responses was not due to delayed senescence. The sugar-induced transduction pathway involved remains unclear. 3-O-methylglucose did not affect chloroplast movements suggesting the participation of a hexokinase-dependent pathway. Only the amplitude of avoidance response was reduced in gin2-1, a hexokinase1 null mutant. Probably other hexokinases, or glycolysis-associated signals play a role in the suppression of chloroplast responses.

  5. Chloroplasts move towards the nearest anticlinal walls under dark condition.

    PubMed

    Tsuboi, Hidenori; Wada, Masamitsu

    2012-03-01

    Chloroplasts change their intracellular positions in response to their light environment. Under darkness, chloroplasts assume special positions that are different from those under light conditions. Here, we analyzed chloroplast dark positioning using Adiantum capillus-veneris gametophyte cells. When chloroplasts were transferred into darkness, during the first 1-5 h, they moved towards the anticlinal cell walls bordering the adjacent cells rather rapidly. Then, they slowed down and accumulated at the anticlinal walls gradually over the following 24-36 h. The chloroplast movements could be roughly classified into two different categories: initial rapid straight movement and later, slow staggering movement. When the chloroplast accumulation response was induced in dark-adapted cells by partial cell irradiation with a microbeam targeted to the center of the cells, chloroplasts moved towards the beam spot from the anticlinal walls. However, when the microbeam was switched off, they moved to the nearest anticlinal walls and not to their original positions if they were not the closest, indicating that they know the direction of the nearest anticlinal wall and do not have particular areas that they migrate to during dark positioning.

  6. Does Chloroplast Size Influence Photosynthetic Nitrogen Use Efficiency?

    PubMed Central

    Li, Yong; Ren, Binbin; Ding, Lei; Shen, Qirong; Peng, Shaobing; Guo, Shiwei

    2013-01-01

    High nitrogen (N) supply frequently results in a decreased photosynthetic N-use efficiency (PNUE), which indicates a less efficient use of accumulated Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Chloroplasts are the location of Rubisco and the endpoint of CO2 diffusion, and they play a vital important role in photosynthesis. However, the effects of chloroplast development on photosynthesis are poorly explored. In the present study, rice seedlings (Oryza sativa L., cv. ‘Shanyou 63’, and ‘Yangdao 6’) were grown hydroponically with three different N levels, morphological characteristics, photosynthetic variables and chloroplast size were measured. In Shanyou 63, a negative relationship between chloroplast size and PNUE was observed across three different N levels. Here, plants with larger chloroplasts had a decreased ratio of mesophyll conductance (gm) to Rubisco content (gm/Rubisco) and a lower Rubisco specific activity. In Yangdao 6, there was no change in chloroplast size and no decline in PNUE or gm/Rubisco ratio under high N supply. It is suggested that large chloroplasts under high N supply is correlated with the decreased Rubisco specific activity and PNUE. PMID:23620801

  7. Import of Soluble Proteins into Chloroplasts and Potential Regulatory Mechanisms

    PubMed Central

    Sjuts, Inga; Soll, Jürgen; Bölter, Bettina

    2017-01-01

    Chloroplasts originated from an endosymbiotic event in which a free-living cyanobacterium was engulfed by an ancestral eukaryotic host. During evolution the majority of the chloroplast genetic information was transferred to the host cell nucleus. As a consequence, proteins formerly encoded by the chloroplast genome are now translated in the cytosol and must be subsequently imported into the chloroplast. This process involves three steps: (i) cytosolic sorting procedures, (ii) binding to the designated receptor-equipped target organelle and (iii) the consecutive translocation process. During import, proteins have to overcome the two barriers of the chloroplast envelope, namely the outer envelope membrane (OEM) and the inner envelope membrane (IEM). In the majority of cases, this is facilitated by two distinct multiprotein complexes, located in the OEM and IEM, respectively, designated TOC and TIC. Plants are constantly exposed to fluctuating environmental conditions such as temperature and light and must therefore regulate protein composition within the chloroplast to ensure optimal functioning of elementary processes such as photosynthesis. In this review we will discuss the recent models of each individual import stage with regard to short-term strategies that plants might use to potentially acclimate to changes in their environmental conditions and preserve the chloroplast protein homeostasis. PMID:28228773

  8. Programmed cell death in plants: A chloroplastic connection

    PubMed Central

    Ambastha, Vivek; Tripathy, Baishnab C; Tiwari, Budhi Sagar

    2015-01-01

    Programmed cell death (PCD) is an integral cellular program by which targeted cells culminate to demise under certain developmental and pathological conditions. It is essential for controlling cell number, removing unwanted diseased or damaged cells and maintaining the cellular homeostasis. The details of PCD process has been very well elucidated and characterized in animals but similar understanding of the process in plants has not been achieved rather the field is still in its infancy that sees some sporadic reports every now and then. The plants have 2 energy generating sub-cellular organelles- mitochondria and chloroplasts unlike animals that just have mitochondria. The presence of chloroplast as an additional energy transducing and ROS generating compartment in a plant cell inclines to advocate the involvement of chloroplasts in PCD execution process. As chloroplasts are supposed to be progenies of unicellular photosynthetic organisms that evolved as a result of endosymbiosis, the possibility of retaining some of the components involved in bacterial PCD by chloroplasts cannot be ruled out. Despite several excellent reviews on PCD in plants, there is a void on an update of information at a place on the regulation of PCD by chloroplast. This review has been written to provide an update on the information supporting the involvement of chloroplast in PCD process and the possible future course of the field. PMID:25760871

  9. ACTION OF TRITON X-100 ON CHLOROPLAST MEMBRANES

    PubMed Central

    Deamer, David W.; Crofts, Antony

    1967-01-01

    Addition of Triton X-100 to chloroplast suspensions to a final concentration of 100–200 µM causes an approximate tripling of chloroplast volume and complete inhibition of light-induced conformational changes, light-dependent hydrogen ion transport, and photophosphorylation. Electron microscopic studies show that chloroplasts treated in this manner manifest extensive swelling in the form of vesicles within their inner membrane structure. Triton was adsorbed to chloroplast membranes in a manner suggesting a partition between the membrane phase and the suspending medium, rather than a strong, irreversible binding. This adsorption results in the production of pores through which ions may freely pass, and it is suggested that the inhibition of conformational changes, hydrogen ion transport, and photophosphorylation by Triton is due to an inability of treated chloroplast membranes to maintain a light-dependent pH gradient. The observed swelling is due to water influx in response to a fixed, osmotically active species within the chloroplasts, after ionic equilibrium has occurred. This is supported by the fact that chloroplasts will shrink upon Triton addition if a nonpenetrating, osmotically active material such as dextran or polyvinylpyrrolidone is present externally in sufficient concentration (>0.1 mM) to offset the osmotic activity of the internal species. PMID:6039379

  10. Does chloroplast size influence photosynthetic nitrogen use efficiency?

    PubMed

    Li, Yong; Ren, Binbin; Ding, Lei; Shen, Qirong; Peng, Shaobing; Guo, Shiwei

    2013-01-01

    High nitrogen (N) supply frequently results in a decreased photosynthetic N-use efficiency (PNUE), which indicates a less efficient use of accumulated Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Chloroplasts are the location of Rubisco and the endpoint of CO2 diffusion, and they play a vital important role in photosynthesis. However, the effects of chloroplast development on photosynthesis are poorly explored. In the present study, rice seedlings (Oryza sativa L., cv. 'Shanyou 63', and 'Yangdao 6') were grown hydroponically with three different N levels, morphological characteristics, photosynthetic variables and chloroplast size were measured. In Shanyou 63, a negative relationship between chloroplast size and PNUE was observed across three different N levels. Here, plants with larger chloroplasts had a decreased ratio of mesophyll conductance (gm) to Rubisco content (gm/Rubisco) and a lower Rubisco specific activity. In Yangdao 6, there was no change in chloroplast size and no decline in PNUE or gm/Rubisco ratio under high N supply. It is suggested that large chloroplasts under high N supply is correlated with the decreased Rubisco specific activity and PNUE.

  11. Chloroplast: The Trojan Horse in Plant-Virus Interaction.

    PubMed

    Bhattacharyya, Dhriti; Chakraborty, Supriya

    2017-01-05

    Chloroplast is one of the most dynamic organelle of a plant cell. It carries out photosynthesis, synthesizes major phytohormones, takes active part in defence response, and is crucial for inter-organelle signaling. Viruses, on the other hand, are extremely strategic in manipulating the internal environment of the host cell. Chloroplast, a prime target for viruses, undergoes enormous structural and functional damage during viral infection. In fact, large proportions of affected gene products in a virus infected plant are closely associated to chloroplast and photosynthesis process. Although chloroplast is deficient in gene-silencing machinery, it elicits effector-triggered immune response against viral pathogens. Virus infection induces the organelle to produce extensive network of stromules which are involved in both viral propagation and anti-viral defence. From last few decades' study, involvement of chloroplast in regulating plant-virus interaction has become increasingly evident. Current review presents an exhaustive account of these facts, with their implication in pathogenicity. We have attempted to highlight the intricacies of chloroplast-virus interaction and explained the existing gaps in current knowledge, which will promote the virologists to utilize the chloroplast genome-based antiviral resistance in economically important crops. This article is protected by copyright. All rights reserved.

  12. Influence of Sugars on Blue Light-Induced Chloroplast Relocations

    PubMed Central

    Banaś, Agnieszka Katarzyna

    2007-01-01

    The aim of this study was to investigate the influence of sugars on blue light-induced chloroplast movements. Sucrose and glucose inhibited chloroplast responses in the detached leaves of Arabidopsis thaliana and in Lemna trisulca fronds in a concentration and time-dependent manner. The prolonged exposure necessary for inhibition indicates that sugars may act via altered gene expression. Overexpression of phototropin2, a photoreceptor responsible for the strong blue light response of chloroplasts, counteracted the sugar effect. This may suggest that sugars modify some component(s) of the phototropin2-mediated signal transduction pathway. The expression of PHOT2 was not suppressed by sugars in wild type plants, it was even upregulated by glucose. Impaired chloroplast movements were observed only in mature Arabidopsis plants. The mRNA of SAG12, a late senescence marker, was not detectable in the sugar-incubated leaves. The SAG13 mRNA level and its regulation by sugars were similar in wild type and PHOT2 overexpressor. Thus, the sugar insensitivity of 35S:PHOT2 chloroplast responses was not due to delayed senescence. The sugar-induced transduction pathway involved remains unclear. 3-O-methylglucose did not affect chloroplast movements suggesting the participation of a hexokinase-dependent pathway. Only the amplitude of avoidance response was reduced in gin2-1, a hexokinase1 null mutant. Probably other hexokinases, or glycolysis-associated signals play a role in the suppression of chloroplast responses. PMID:19516992

  13. Transposon-induced nuclear mutations that alter chloroplast gene expression

    SciTech Connect

    Barkan, A.

    1992-01-01

    The goal of this project is to use mutant phenotypes as a guide to nuclear genes that determine the timing and localization of chloroplast development The immediate goals are to identify nuclear mutants with defects in chloroplast gene expression from maize lines harboring active Mu transposons; characterize their phenotypes to determine the precise defect in gene expression; clone several of the most interesting mutations by exploiting the transposon tag; and use the clones to further define the roles of these genes in modulating chloroplast gene expression. Three mutants were described earlier that had global defects in chloroplast gene expression. We have found that two of these mutations are allelic. Both alleles have global defects in chloroplast translation initiation, as revealed by the failure to assemble chloroplast mRNAs into polysomes. We have isolated and characterized three new mutants from Mu lines that have novel defects in chloroplast RNA metabolism. We are now ready to begin the task of cloning several of these genes, by using the Mu transposon tag.

  14. Proteomics of the chloroplast envelope membranes from Arabidopsis thaliana.

    PubMed

    Ferro, Myriam; Salvi, Daniel; Brugière, Sabine; Miras, Stéphane; Kowalski, Solène; Louwagie, Mathilde; Garin, Jérôme; Joyard, Jacques; Rolland, Norbert

    2003-05-01

    The development of chloroplasts and the integration of their function within a plant cell rely on the presence of a complex biochemical machinery located within their limiting envelope membranes. To provide the most exhaustive view of the protein repertoire of chloroplast envelope membranes, we analyzed this membrane system using proteomics. To this purpose, we first developed a procedure to prepare highly purified envelope membranes from Arabidopsis chloroplasts. We then extracted envelope proteins using different methods, i.e. chloroform/methanol extraction and alkaline or saline treatments, in order to retrieve as many proteins as possible, from the most to least hydrophobic ones. Liquid chromatography tandem mass spectrometry analyses were then performed on each envelope membrane subfraction, leading to the identification of more than 100 proteins. About 80% of the identified proteins are known to be, or are very likely, located in the chloroplast envelope. The validation of localization in the envelope of two phosphate transporters exemplifies the need for a combination of strategies to perform the most exhaustive identification of genuine chloroplast envelope proteins. Interestingly, some of the identified proteins are found to be Nalpha-acetylated, which indicates the accurate location of the N terminus of the corresponding mature protein. With regard to function, more than 50% of the identified proteins have functions known or very likely to be associated with the chloroplast envelope. These proteins are a) involved in ion and metabolite transport, b) components of the protein import machinery, and c) involved in chloroplast lipid metabolism. Some soluble proteins, like proteases, proteins involved in carbon metabolism, or proteins involved in responses to oxidative stress, were associated with envelope membranes. Almost one-third of the proteins we identified have no known function. The present work helps understanding chloroplast envelope metabolism at

  15. Fine tuning chloroplast movements through physical interactions between phototropins.

    PubMed

    Sztatelman, Olga; Łabuz, Justyna; Hermanowicz, Paweł; Banaś, Agnieszka Katarzyna; Bażant, Aneta; Zgłobicki, Piotr; Aggarwal, Chhavi; Nadzieja, Marcin; Krzeszowiec, Weronika; Strzałka, Wojciech; Gabryś, Halina

    2016-09-01

    Phototropins are plant photoreceptors which regulate numerous responses to blue light, including chloroplast relocation. Weak blue light induces chloroplast accumulation, whereas strong light leads to an avoidance response. Two Arabidopsis phototropins are characterized by different light sensitivities. Under continuous light, both can elicit chloroplast accumulation, but the avoidance response is controlled solely by phot2. As well as continuous light, brief light pulses also induce chloroplast displacements. Pulses of 0.1s and 0.2s of fluence rate saturating the avoidance response lead to transient chloroplast accumulation. Longer pulses (up to 20s) trigger a biphasic response, namely transient avoidance followed by transient accumulation. This work presents a detailed study of transient chloroplast responses in Arabidopsis. Phototropin mutants display altered chloroplast movements as compared with the wild type: phot1 is characterized by weaker responses, while phot2 exhibits enhanced chloroplast accumulation, especially after 0.1s and 0.2s pulses. To determine the cause of these differences, the abundance and phosphorylation levels of both phototropins, as well as the interactions between phototropin molecules are examined. The formation of phototropin homo- and heterocomplexes is the most plausible explanation of the observed phenomena. The physiological consequences of this interplay are discussed, suggesting the universal character of this mechanism that fine-tunes plant reactions to blue light. Additionally, responses in mutants of different protein phosphatase 2A subunits are examined to assess the role of protein phosphorylation in signaling of chloroplast movements. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  16. Production of therapeutic proteins in the chloroplast of Chlamydomonas reinhardtii

    PubMed Central

    2014-01-01

    Chloroplast transformation in the photosynthetic alga Chlamydomonas reinhardtii has been used to explore the potential to use it as an inexpensive and easily scalable system for the production of therapeutic recombinant proteins. Diverse proteins, such as bacterial and viral antigens, antibodies and, immunotoxins have been successfully expressed in the chloroplast using endogenous and chimeric promoter sequences. In some cases, proteins have accumulated to high level, demonstrating that this technology could compete with current production platforms. This review focuses on the works that have engineered the chloroplast of C. reinhardtii with the aim of producing recombinant proteins intended for therapeutical use in humans or animals. PMID:25136510

  17. Production of therapeutic proteins in the chloroplast of Chlamydomonas reinhardtii.

    PubMed

    Almaraz-Delgado, Alma Lorena; Flores-Uribe, José; Pérez-España, Víctor Hugo; Salgado-Manjarrez, Edgar; Badillo-Corona, Jesús Agustín

    2014-01-01

    Chloroplast transformation in the photosynthetic alga Chlamydomonas reinhardtii has been used to explore the potential to use it as an inexpensive and easily scalable system for the production of therapeutic recombinant proteins. Diverse proteins, such as bacterial and viral antigens, antibodies and, immunotoxins have been successfully expressed in the chloroplast using endogenous and chimeric promoter sequences. In some cases, proteins have accumulated to high level, demonstrating that this technology could compete with current production platforms. This review focuses on the works that have engineered the chloroplast of C. reinhardtii with the aim of producing recombinant proteins intended for therapeutical use in humans or animals.

  18. Chloroplast microsatellite primers for cacao (Theobroma cacao) and other Malvaceae.

    PubMed

    Yang, Ji Y; Motilal, Lambert A; Dempewolf, Hannes; Maharaj, Kamaldeo; Cronk, Q C B

    2011-12-01

    Chloroplast microsatellites were developed in Theobroma cacao to examine the genetic diversity of cacao cultivars in Trinidad and Tobago. Nine polymorphic microsatellites were designed from the chloroplast genomes of two T. cacao accessions. These microsatellites were tested in 95 hybrid accessions from Trinidad and Tobago. An average of 2.9 alleles per locus was found. These chloroplast microsatellites, particularly the highly polymorphic pentameric repeat, were useful in assessing genetic variation in T. cacao. In addition, these markers should also prove to be useful for population genetic studies in other species of Malvaceae.

  19. Seamless editing of the chloroplast genome in plants.

    PubMed

    Martin Avila, Elena; Gisby, Martin F; Day, Anil

    2016-07-29

    Gene editing technologies enable the precise insertion of favourable mutations and performance enhancing trait genes into chromosomes whilst excluding all excess DNA from modified genomes. The technology gives rise to a new class of biotech crops which is likely to have widespread applications in agriculture. Despite progress in the nucleus, the seamless insertions of point mutations and non-selectable foreign genes into the organelle genomes of crops have not been described. The chloroplast genome is an attractive target to improve photosynthesis and crop performance. Current chloroplast genome engineering technologies for introducing point mutations into native chloroplast genes leave DNA scars, such as the target sites for recombination enzymes. Seamless editing methods to modify chloroplast genes need to address reversal of site-directed point mutations by template mediated repair with the vast excess of wild type chloroplast genomes that are present early in the transformation process. Using tobacco, we developed an efficient two-step method to edit a chloroplast gene by replacing the wild type sequence with a transient intermediate. This was resolved to the final edited gene by recombination between imperfect direct repeats. Six out of 11 transplastomic plants isolated contained the desired intermediate and at the second step this was resolved to the edited chloroplast gene in five of six plants tested. Maintenance of a single base deletion mutation in an imperfect direct repeat of the native chloroplast rbcL gene showed the limited influence of biased repair back to the wild type sequence. The deletion caused a frameshift, which replaced the five C-terminal amino acids of the Rubisco large subunit with 16 alternative residues resulting in a ~30-fold reduction in its accumulation. We monitored the process in vivo by engineering an overlapping gusA gene downstream of the edited rbcL gene. Translational coupling between the overlapping rbcL and gusA genes

  20. Chloroplast DNA variation of Quercus rubra L. in North America and comparison with other Fagaceae.

    PubMed

    Magni, C R; Ducousso, A; Caron, H; Petit, R J; Kremer, A

    2005-02-01

    Quercus rubra is one of the most important timber and ornamental tree species from eastern North America. It is a widespread species growing under variable ecological conditions. Chloroplast DNA variation was studied by PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) in 290 individuals from 66 populations sampled throughout the natural range. A total of 12 haplotypes were detected, with one found in 75% of the trees. Population differentiation is relatively low (G(ST) = 0.46), even when similarities between haplotypes are taken into account (N(ST) = 0.50), pointing to a weak phylogeographical structure. Furthermore, no spatial structure of genetic diversity could be detected. The genetic differentiation increased northwards, reflecting the postglacial history of Q. rubra. The unusual aspect of this study was the low level of chloroplast DNA genetic differentiation in Q. rubra compared to that typically observed in other oak species. Palynological evidence indicates that during the last glacial maximum, Q. rubra had one major distribution range with populations located relatively far to the north, resulting in only modest movement northwards when climate improved, whereas European white oaks were largely restricted to the southern European peninsulas and experienced extensive movements during the postglacial period. The contrasted geographical features and levels of tree species richness of both continents might further explain why congeneric species sharing similar life history traits have genetic structures that are so different.

  1. Population structure and genetic diversity in tristylous Narcissus triandrus: insights from microsatellite and chloroplast DNA variation.

    PubMed

    Hodgins, Kathryn A; Barrett, Spencer C H

    2007-06-01

    We investigated cpDNA sequence and nuclear microsatellite variation among populations of the wild daffodil Narcissus triandrus to examine the role of historical vs. contemporary forces in shaping population structure, morphological differentiation and sexual-system evolution. This wide-ranging heterostylous species of the Iberian Peninsula is largely composed of two allopatric varieties (vars. cernuus and triandrus), and populations with either stylar trimorphism or dimorphism. Dimorphic populations only occur in var. triandrus, are mainly restricted to the northwestern portion of the species range, and uniformly lack the mid-styled morph (M-morph). Chloroplast DNA (cpDNA) sequence variation revealed strong geographical structuring and evidence for a fragmentation event associated with differentiation of the two varieties. In var. triandrus, population fragmentation, restricted gene flow and isolation-by-distance were also inferred. Significant differences in genetic diversity and population structure between the two varieties likely reflect historical and contemporary differences in demography and gene flow among populations. Discordance between cpDNA markers and both microsatellite and morphological variation indicate that hybridization has occurred between the two varieties at contact zones. There were no differences in genetic diversity or population structure between dimorphic and trimorphic populations, and chloroplast haplotypes were not associated with either sexual system, indicating transitions in morph structure within each maternal lineage. M-morph frequencies were positively correlated with differentiation at microsatellite loci, indicating that the evolutionary processes influencing these neutral markers also influence alleles controlling the style morphs.

  2. Differential responses of seabirds to inter-annual environmental change in the continental shelf and oceanic habitats of southeastern Bering Sea

    NASA Astrophysics Data System (ADS)

    Yamamoto, T.; Kokubun, N.; Kikuchi, D. M.; Sato, N.; Takahashi, A.; Will, A.; Kitaysky, A. S.; Watanuki, Y.

    2015-11-01

    Seasonal sea-ice cover has been decreasing in the southeastern Bering Sea shelf, which might affect ecosystem dynamics and availability of food resources to marine top predators breeding in the region. In this study, we investigated the foraging responses of two seabird species, surface-foraging red-legged kittiwakes Rissa brevirostris (hereafter, RLKI) and pursuit-diving foraging thick-billed murres Uria lomvia (TBMU) to the inter-annual change in environmental conditions. Between the study years, winter ice retreated earlier and summer water temperatures were warmer in 2014 compared to those in 2013. At-sea distributions of RLKI and TBMU breeding on St. George Island, the largest seabird colony in the region, were recorded using GPS loggers, and blood samples were taken to examine their physiological condition and isotopic foraging niche in a given year. RLKI foraging occurred mostly over the oceanic basin in both years. TBMU, however, foraged mostly over the shelf, but showed a relatively higher use of the shelf break and oceanic basin in the colder year, 2013. The foraging distances from the colony peaked at 250-300 km in 2013 and, bimodally, at 150-250 and 300-350 km in 2014 for RLKI, and tended to be farther in 2013 compared to those in 2014 for TBMU. Plasma levels of corticosterone did not differ between years in RLKI, but differed in TBMU, showing higher levels of physiological stress incurred by murres during the colder year, 2013. δ13N (a proxy of trophic level of prey) did not differ between the years in either RLKI or TBMU, while δ13C (a proxy of prey origin) were lower in 2014 than in 2013 in both species, suggesting possible differences in influx of oceanic prey items into foraging areas. These results suggest that the response of ecosystem dynamics to climate variability in the southeast Bering Sea may differ between the ocean basin and continental shelf regions, which, in turn, may generate differential responses in seabirds relying on those

  3. Chloroplast biogenesis: The use of mutants to study the etioplast–chloroplast transition

    PubMed Central

    Philippar, Katrin; Geis, Tina; Ilkavets, Iryna; Oster, Ulrike; Schwenkert, Serena; Meurer, Jörg; Soll, Jürgen

    2007-01-01

    In angiosperm plants, the etioplast–chloroplast transition is light-dependent. A key factor in this process is the protochlorophyllide oxidoreductase A (PORA), which catalyzes the light-induced reduction of protochlorophyllide to chlorophyllide. The import pathway of the precursor protein prePORA into chloroplasts was analyzed in vivo and in vitro by using homozygous loss-of-function mutants in genes coding for chlorophyllide a oxygenase (CAO) or for members of the outer-envelope solute-channel protein family of 16 kDa (OEP16), both of which have been implied to be key factors for the import of prePORA. Our in vivo analyses show that cao or oep16 mutants contain a normally structured prolamellar body that contains the protochlorophyllide holochrome. Furthermore, etioplasts from cao and oep16 mutants contain PORA protein as found by mass spectrometry. Our data demonstrate that both CAO and OEP16 are dispensable for chloroplast biogenesis and play no central role in the import of prePORA in vivo and in vitro as further indicated by protein import studies. PMID:17202255

  4. Chloroplast biogenesis: the use of mutants to study the etioplast-chloroplast transition.

    PubMed

    Philippar, Katrin; Geis, Tina; Ilkavets, Iryna; Oster, Ulrike; Schwenkert, Serena; Meurer, Jörg; Soll, Jürgen

    2007-01-09

    In angiosperm plants, the etioplast-chloroplast transition is light-dependent. A key factor in this process is the protochlorophyllide oxidoreductase A (PORA), which catalyzes the light-induced reduction of protochlorophyllide to chlorophyllide. The import pathway of the precursor protein prePORA into chloroplasts was analyzed in vivo and in vitro by using homozygous loss-of-function mutants in genes coding for chlorophyllide a oxygenase (CAO) or for members of the outer-envelope solute-channel protein family of 16 kDa (OEP16), both of which have been implied to be key factors for the import of prePORA. Our in vivo analyses show that cao or oep16 mutants contain a normally structured prolamellar body that contains the protochlorophyllide holochrome. Furthermore, etioplasts from cao and oep16 mutants contain PORA protein as found by mass spectrometry. Our data demonstrate that both CAO and OEP16 are dispensable for chloroplast biogenesis and play no central role in the import of prePORA in vivo and in vitro as further indicated by protein import studies.

  5. Transformation of the Cyanidioschyzon merolae chloroplast genome: prospects for understanding chloroplast function in extreme environments.

    PubMed

    Zienkiewicz, Maksymilian; Krupnik, Tomasz; Drożak, Anna; Golke, Anna; Romanowska, Elżbieta

    2017-01-01

    We have successfully transformed an exthemophilic red alga with the chloramphenicol acetyltransferase gene, rendering this organism insensitive to its toxicity. Our work paves the way to further work with this new modelorganism. Here we report the first successful attempt to achieve a stable, under selectable pressure, chloroplast transformation in Cyanidioschizon merolae-an extremophilic red alga of increasing importance as a new model organism. The following protocol takes advantage of a double homologous recombination phenomenon in the chloroplast, allowing to introduce an exogenous, selectable gene. For that purpose, we decided to use chloramphenicol acetyltransferase (CAT), as chloroplasts are particularly vulnerable to chloramphenicol lethal effects (Zienkiewicz et al. in Protoplasma, 2015, doi: 10.1007/s00709-015-0936-9 ). We adjusted two methods of DNA delivery: the PEG-mediated delivery and the biolistic bombardment based delivery, either of these methods work sufficiently with noticeable preference to the former. Application of a codon-optimized sequence of the cat gene and a single colony selection yielded C. merolae strains, capable of resisting up to 400 µg/mL of chloramphenicol. Our method opens new possibilities in production of site-directed mutants, recombinant proteins and exogenous protein overexpression in C. merolae-a new model organism.

  6. Complete chloroplast genome sequences of Solanum commersonii and its application to chloroplast genotype in somatic hybrids with Solanum tuberosum.

    PubMed

    Cho, Kwang-Soo; Cheon, Kyeong-Sik; Hong, Su-Young; Cho, Ji-Hong; Im, Ju-Seong; Mekapogu, Manjulatha; Yu, Yei-Soo; Park, Tae-Ho

    2016-10-01

    Chloroplast genome of Solanum commersonii and S olanum tuberosum were completely sequenced, and Indel markers were successfully applied to distinguish chlorotypes demonstrating the chloroplast genome was randomly distributed during protoplast fusion. Somatic hybridization has been widely employed for the introgression of resistance to several diseases from wild Solanum species to overcome sexual barriers in potato breeding. Solanum commersonii is a major resource used as a parent line in somatic hybridization to improve bacterial wilt resistance in interspecies transfer to cultivated potato (S. tuberosum). Here, we sequenced the complete chloroplast genomes of Lz3.2 (S. commersonii) and S. tuberosum (PT56), which were used to develop fusion products, then compared them with those of five members of the Solanaceae family, S. tuberosum, Capsicum annum, S. lycopersicum, S. bulbocastanum and S. nigrum and Coffea arabica as an out-group. We then developed Indel markers for application in chloroplast genotyping. The complete chloroplast genome of Lz3.2 is composed of 155,525 bp, which is larger than the PT56 genome with 155,296 bp. Gene content, order and orientation of the S. commersonii chloroplast genome were highly conserved with those of other Solanaceae species, and the phylogenetic tree revealed that S. commersonii is located within the same node of S. tuberosum. However, sequence alignment revealed nine Indels between S. commersonii and S. tuberosum in their chloroplast genomes, allowing two Indel markers to be developed. The markers could distinguish the two species and were successfully applied to chloroplast genotyping (chlorotype) in somatic hybrids and their progenies. The results obtained in this study confirmed the random distribution of the chloroplast genome during protoplast fusion and its maternal inheritance and can be applied to select proper plastid genotypes in potato breeding program.

  7. Chloroplast Phylogenomic Inference of Green Algae Relationships.

    PubMed

    Sun, Linhua; Fang, Ling; Zhang, Zhenhua; Chang, Xin; Penny, David; Zhong, Bojian

    2016-02-05

    The green algal phylum Chlorophyta has six diverse classes, but the phylogenetic relationship of the classes within Chlorophyta remains uncertain. In order to better understand the ancient Chlorophyta evolution, we have applied a site pattern sorting method to study compositional heterogeneity and the model fit in the green algal chloroplast genomic data. We show that the fastest-evolving sites are significantly correlated with among-site compositional heterogeneity, and these sites have a much poorer fit to the evolutionary model. Our phylogenomic analyses suggest that the class Chlorophyceae is a monophyletic group, and the classes Ulvophyceae, Trebouxiophyceae and Prasinophyceae are non-monophyletic groups. Our proposed phylogenetic tree of Chlorophyta will offer new insights to investigate ancient green algae evolution, and our analytical framework will provide a useful approach for evaluating and mitigating the potential errors of phylogenomic inferences.

  8. Origins of prokaryotes, eukaryotes, mitochondria, and chloroplasts

    NASA Technical Reports Server (NTRS)

    Schwartz, R. M.; Dayhoff, M. O.

    1978-01-01

    A computer branching model is used to analyze cellular evolution. Attention is given to certain key amino acids and nucleotide residues (ferredoxin, 5s ribosomal RNA, and c-type cytochromes) because of their commonality over a wide variety of cell types. Each amino acid or nucleotide residue is a sequence in an inherited biological trait; and the branching method is employed to align sequences so that changes reflect substitution of one residue for another. Based on the computer analysis, the symbiotic theory of cellular evolution is considered the most probable. This theory holds that organelles, e.g., mitochondria and chloroplasts invaded larger bodies, e.g., bacteria, and combined functions to form eucaryotic cells.

  9. Origins of prokaryotes, eukaryotes, mitochondria, and chloroplasts

    NASA Technical Reports Server (NTRS)

    Schwartz, R. M.; Dayhoff, M. O.

    1978-01-01

    A computer branching model is used to analyze cellular evolution. Attention is given to certain key amino acids and nucleotide residues (ferredoxin, 5s ribosomal RNA, and c-type cytochromes) because of their commonality over a wide variety of cell types. Each amino acid or nucleotide residue is a sequence in an inherited biological trait; and the branching method is employed to align sequences so that changes reflect substitution of one residue for another. Based on the computer analysis, the symbiotic theory of cellular evolution is considered the most probable. This theory holds that organelles, e.g., mitochondria and chloroplasts invaded larger bodies, e.g., bacteria, and combined functions to form eucaryotic cells.

  10. Preparation and proteomic analysis of chloroplast ribosomes.

    PubMed

    Yamaguchi, Kenichi

    2011-01-01

    Proteomics of chloroplast ribosomes in spinach and Chlamydomonas revealed unique protein composition and structures of plastid ribosomes. These studies have suggested the presence of some ribosomal proteins unique to plastid ribosomes which may be involved in plastid-unique translation regulation. Considering the strong background of genetic analysis and molecular biology in Arabidopsis, the in-depth proteomic characterization of Arabidopsis plastid ribosomes would facilitate further understanding of plastid translation in higher plants. Here, I describe simple and rapid methods for the preparation of plastid ribosomes from Chlamydomonas and Arabidopsis using sucrose gradients. I also describe purity criteria and methods for yield estimation of the purified plastid ribosomes and subunits, methods for the preparation of plastid ribosomal proteins, as well as the identification of some Arabidopsis plastid ribosomal proteins by matrix-assisted laser desorption/ionization mass spectrometry.

  11. Chloroplast Phylogenomic Inference of Green Algae Relationships

    PubMed Central

    Sun, Linhua; Fang, Ling; Zhang, Zhenhua; Chang, Xin; Penny, David; Zhong, Bojian

    2016-01-01

    The green algal phylum Chlorophyta has six diverse classes, but the phylogenetic relationship of the classes within Chlorophyta remains uncertain. In order to better understand the ancient Chlorophyta evolution, we have applied a site pattern sorting method to study compositional heterogeneity and the model fit in the green algal chloroplast genomic data. We show that the fastest-evolving sites are significantly correlated with among-site compositional heterogeneity, and these sites have a much poorer fit to the evolutionary model. Our phylogenomic analyses suggest that the class Chlorophyceae is a monophyletic group, and the classes Ulvophyceae, Trebouxiophyceae and Prasinophyceae are non-monophyletic groups. Our proposed phylogenetic tree of Chlorophyta will offer new insights to investigate ancient green algae evolution, and our analytical framework will provide a useful approach for evaluating and mitigating the potential errors of phylogenomic inferences. PMID:26846729

  12. Chloroplast Microsatellite Diversity in Phaseolus vulgaris

    PubMed Central

    Desiderio, F.; Bitocchi, E.; Bellucci, E.; Rau, D.; Rodriguez, M.; Attene, G.; Papa, R.; Nanni, L.

    2012-01-01

    Evolutionary studies that are aimed at defining the processes behind the present level and organization of crop genetic diversity represent the fundamental bases for biodiversity conservation and use. A Mesoamerican origin of the common bean Phaseolus vulgaris was recently suggested through analysis of nucleotide polymorphism at the nuclear level. Here, we have used chloroplast microsatellites to investigate the origin of the common bean, on the basis of the specific characteristics of these markers (no recombination, haploid genome, uniparental inheritance), to validate these recent findings. Indeed, comparisons of the results obtained through analysis of nuclear and cytoplasmic DNA should allow the resolution of some of the contrasting information available on the evolutionary processes. The main outcomes of the present study are: (i) confirmation at the chloroplast level of the results obtained through nuclear data, further supporting the Mesoamerican origin of P. vulgaris, with central Mexico representing the cradle of its diversity; (ii) identification of a putative ancestral plastidial genome, which is characteristic of a group of accessions distributed from central Mexico to Peru, but which have not been highlighted beforehand through analyses at the nuclear level. Finally, the present study suggests that when a single species is analyzed, there is the need to take into account the complexity of the relationships between P. vulgaris and its closely related and partially intercrossable species P. coccineus and P. dumosus. Thus, the present study stresses the importance for the investigation of the speciation processes of these taxa through comparisons of both plastidial and nuclear variability. This knowledge will be fundamental not only from an evolutionary point of view, but also to put P. coccineus and P. dumosus germplasm to better use as a source of useful diversity for P. vulgaris breeding. PMID:23346091

  13. Biosynthesis of gold nanoparticles using chloroplasts.

    PubMed

    Zhang, Yi Xia; Zheng, Jun; Gao, Guo; Kong, Yi Fei; Zhi, Xiao; Wang, Kan; Zhang, Xue Qing; Cui, Da Xiang

    2011-01-01

    In this paper, a new method of one-pot biosynthesizing of gold nanoparticles (GNPs), using chloroplasts as reductants and stabilizers is reported. The as-prepared GNPs were characterized by ultraviolet visible spectroscopy, transmission electron microscopy, X-ray powder diffraction, and Fourier transform infrared spectroscopy (FTIR). The cytotoxicity of the GNPs was evaluated using the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method against gastric mucous cell line GES-1 and gastric cancer cell line MGC-803. Rhodamine 6G as a Raman probe was used for investigating surface-enhanced Raman spectroscopy (SERS) enhancement of GNPs. The transmission electron microscopy results indicated that the GNPs were spherical in structure and almost 20 nm in diameter. Ultraviolet visible spectroscopy exhibited an absorption peak at 545 nm. The GNPs exhibited high crystallinity, with the (111) plane as the predominant orientation, clarified by X-ray powder diffraction. In addition, a potential mechanism was proposed to interpret the formation process of GNPs, mainly based on the analysis of FTIR results. The FTIR spectrum confirmed that the GNPs were carried with N-H groups. Toxicological assays of as-prepared GNPs revealed that the green GNPs were nontoxic. SERS analysis revealed that the GNPs without any treatment could substantially enhance the Raman signals of rhodamine 6G. The Raman enhancement factor was calculated to be nearly 10(10) orders of magnitude. In conclusion, the GNPs with good biocompatibility and excellent SERS effect were successfully synthesized using chloroplasts. These biogenetic GNPs have great potential for ultrasensitive detection of biomarkers in vitro and in vivo based on SERS.

  14. Participation of chloroplasts in plant apoptosis.

    PubMed

    Samuilov, Vitaly D; Lagunova, Elena M; Kiselevsky, Dmitry B; Dzyubinskaya, Elena V; Makarova, Yana V; Gusev, Mikhail V

    2003-01-01

    Mitochondria are known to participate in the initiation of programmed cell death (PCD) in animals and in plants. The role of chloroplasts in PCD is still unknown. We describe a new system to study PCD in plants; namely, leaf epidermal peels. The peel represents a monolayer consisting of cells of two types: phototrophic (guard cells) and chemotrophic (epidermal cells). The peels from pea (Pisum sativum L.) leaves were treated by cyanide as an inducer of PCD. We found an apoptosis-enhancing effect of illumination on chloroplast-containing guard cells, but not on chloroplastless epidermal cells. Antioxidants and anaerobiosis prevented the CN(-)-induced apoptosis of cells of both types in the dark and in the light. On the other hand, methyl viologen and menadione known as ROS-generating reagents as well as the Hill reaction electron acceptors (BQ, DAD, TMPD, or DPIP) that are not oxidized spontaneously by O2 were shown to prevent the CN(-)-induced nucleus destruction in guard cells. Apoptosis of epidermal cells was potentiated by these reagents, and they had no influence on the CN- effect. The light-dependent activation of CN(-)-induced apoptosis of guard cells was suppressed by DCMU, stigmatellin or DNP-INT, by a protein kinase inhibitor staurosporine as well as by cysteine and serine protease inhibitors. The above data suggest that apoptosis of guard cells is initiated upon a combined action of two factors, i.e., ROS and reduced plastoquinone of the photosynthetic electron transfer chain. As to reduction of ubiquinone in the mitochondrial respiratory chain, it seems to be antiapoptotic for the guard cell.

  15. Chloroplast Microsatellite Diversity in Phaseolus vulgaris.

    PubMed

    Desiderio, F; Bitocchi, E; Bellucci, E; Rau, D; Rodriguez, M; Attene, G; Papa, R; Nanni, L

    2012-01-01

    Evolutionary studies that are aimed at defining the processes behind the present level and organization of crop genetic diversity represent the fundamental bases for biodiversity conservation and use. A Mesoamerican origin of the common bean Phaseolus vulgaris was recently suggested through analysis of nucleotide polymorphism at the nuclear level. Here, we have used chloroplast microsatellites to investigate the origin of the common bean, on the basis of the specific characteristics of these markers (no recombination, haploid genome, uniparental inheritance), to validate these recent findings. Indeed, comparisons of the results obtained through analysis of nuclear and cytoplasmic DNA should allow the resolution of some of the contrasting information available on the evolutionary processes. The main outcomes of the present study are: (i) confirmation at the chloroplast level of the results obtained through nuclear data, further supporting the Mesoamerican origin of P. vulgaris, with central Mexico representing the cradle of its diversity; (ii) identification of a putative ancestral plastidial genome, which is characteristic of a group of accessions distributed from central Mexico to Peru, but which have not been highlighted beforehand through analyses at the nuclear level. Finally, the present study suggests that when a single species is analyzed, there is the need to take into account the complexity of the relationships between P. vulgaris and its closely related and partially intercrossable species P. coccineus and P. dumosus. Thus, the present study stresses the importance for the investigation of the speciation processes of these taxa through comparisons of both plastidial and nuclear variability. This knowledge will be fundamental not only from an evolutionary point of view, but also to put P. coccineus and P. dumosus germplasm to better use as a source of useful diversity for P. vulgaris breeding.

  16. Full transcription of the chloroplast genome in photosynthetic eukaryotes

    PubMed Central

    Shi, Chao; Wang, Shuo; Xia, En-Hua; Jiang, Jian-Jun; Zeng, Fan-Chun; Gao, Li-Zhi

    2016-01-01

    Prokaryotes possess a simple genome transcription system that is different from that of eukaryotes. In chloroplasts (plastids), it is believed that the prokaryotic gene transcription features govern genome transcription. However, the polycistronic operon transcription model cannot account for all the chloroplast genome (plastome) transcription products at whole-genome level, especially regarding various RNA isoforms. By systematically analyzing transcriptomes of plastids of algae and higher plants, and cyanobacteria, we find that the entire plastome is transcribed in photosynthetic green plants, and that this pattern originated from prokaryotic cyanobacteria — ancestor of the chloroplast genomes that diverged about 1 billion years ago. We propose a multiple arrangement transcription model that multiple transcription initiations and terminations combine haphazardly to accomplish the genome transcription followed by subsequent RNA processing events, which explains the full chloroplast genome transcription phenomenon and numerous functional and/or aberrant pre-RNAs. Our findings indicate a complex prokaryotic genome regulation when processing primary transcripts. PMID:27456469

  17. Transport of Ions Across the Inner Envelope Membrane of Chloroplasts

    SciTech Connect

    McCarty, R. E.

    2004-06-02

    The technical report outlines the results of nine years of research on how ions cross the inner envelope membrane of chloroplasts. The ions include protons, nitrite, calcium and ferrous iron. Bicarbonate transport was also studied.

  18. Synthesis of Proteins by Isolated Euglena gracilis Chloroplasts 1

    PubMed Central

    Vasconcelos, Aurea C.

    1976-01-01

    Intact Euglena gracilis chloroplasts, which had been purified on gradients of silica sol, incorporated [35S]methionine or [3H]leucine into soluble and membrane-bound products, using light as the only source of energy. The chloroplasts were osmotically shocked, fractionated on discontinuous gradients of sucrose, and the products of protein synthesis of the different fractions characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The soluble fraction resolved into three zones of radioactivity, the major one corresponding to the large subunit or ribulose diphosphate carboxylase. The thylakoid membrane fraction contained nine labeled polypeptides, the two most prominent in the region of 31 and 42 kilodaltons. The envelope fraction contained a major radioactive peak of about 48 kilodaltons and four other minor peaks. The patterns of protein synthesis by isolated Euglena chloroplasts are broadly similar to those observed with chloroplasts of spinach and pea. PMID:16659752

  19. Photosynthetic light reactions: integral to chloroplast retrograde signalling.

    PubMed

    Gollan, Peter J; Tikkanen, Mikko; Aro, Eva-Mari

    2015-10-01

    Chloroplast retrograde signalling is ultimately dependent on the function of the photosynthetic light reactions and not only guides the acclimation of the photosynthetic apparatus to changing environmental and metabolic cues, but has a much wider influence on the growth and development of plants. New information generated during the past few years about regulation of photosynthetic light reactions and identification of the underlying regulatory proteins has paved the way towards better understanding of the signalling molecules produced in chloroplasts upon changes in the environment. Likewise, the availability of various mutants lacking regulatory functions has made it possible to address the role of excitation energy distribution and electron flow in the thylakoid membrane in inducing the retrograde signals from chloroplasts to the nucleus. Such signalling molecules also induce and interact with hormonal signalling cascades to provide comprehensive information from chloroplasts to the nucleus.

  20. Chloroplast genome variation in upland and lowland switchgrass

    USDA-ARS?s Scientific Manuscript database

    Switchgrass (Panicum virgatum L.) exists at multiple ploidies and two phenotypically distinct ecotypes. To facilitate interploidal comparisons and to understand the extent of sequence variation within existing breeding pools, two complete switchgrass chloroplast genomes were sequenced from individu...

  1. Separation of Chloroplast Pigments Using Reverse Phase Chromatography.

    ERIC Educational Resources Information Center

    Reese, R. Neil

    1997-01-01

    Presents a protocol that uses reverse phase chromatography for the separation of chloroplast pigments. Provides a simple and relatively safe procedure for use in teaching laboratories. Discusses pigment extraction, chromatography, results, and advantages of the process. (JRH)

  2. Protein disulfide isomerase as a regulator of chloroplast translational activation

    SciTech Connect

    Kim, Jungmook; Mayfield, S.P.

    1997-12-12

    Light-regulated translation of chloroplast messenger RNAs (mRNAs) requires transacting factors that interact with the 5{prime} untranslated region (UTR) of these mRNAs. Chloroplast polyadenylate-binding protein (cPABP) specifically binds to the 5{prime}-UTR of the psbA mRNA and is essential for translation of this mRNA. A protein disulfide isomeriase that is localized to the chloroplast and copurifies with cPABP was shown to modulate the binding of cPABP to the 5{prime}-UTR of the psbA mRNA by reversibly changing the redox status of cPaBP through redox potential or adenosine 5{prime}-diphosphate-dependent phosphorylation. This mechanism allows for a simple reversible switch regulating gene expression in the chloroplast. 23 refs., 5 figs.

  3. Separation of Chloroplast Pigments Using Reverse Phase Chromatography.

    ERIC Educational Resources Information Center

    Reese, R. Neil

    1997-01-01

    Presents a protocol that uses reverse phase chromatography for the separation of chloroplast pigments. Provides a simple and relatively safe procedure for use in teaching laboratories. Discusses pigment extraction, chromatography, results, and advantages of the process. (JRH)

  4. A Nucleus-Encoded Chloroplast Protein YL1 Is Involved in Chloroplast Development and Efficient Biogenesis of Chloroplast ATP Synthase in Rice

    PubMed Central

    Chen, Fei; Dong, Guojun; Wu, Limin; Wang, Fang; Yang, Xingzheng; Ma, Xiaohui; Wang, Haili; Wu, Jiahuan; Zhang, Yanli; Wang, Huizhong; Qian, Qian; Yu, Yanchun

    2016-01-01

    Chloroplast ATP synthase (cpATPase) is an importance thylakoid membrane-associated photosynthetic complex involved in the light-dependent reactions of photosynthesis. In this study, we isolated and characterized a rice (Oryza sativa) mutant yellow leaf 1 (yl1), which exhibits chlorotic leaves throughout developmental stages. The YL1 mutation showed reduced chlorophyll contents, abnormal chloroplast morphology, and decreased photochemical efficiency. Moreover, YL1 deficiency disrupts the expression of genes associated with chloroplast development and photosynthesis. Molecular and genetic analyses revealed that YL1 is a nucleus-encoded protein with a predicted transmembrane domain in its carboxyl-terminus that is conserved in the higher plant kingdom. YL1 localizes to chloroplasts and is preferentially expressed in green tissues containing chloroplasts. Immunoblot analyses showed that inactivation of YL1 leads to drastically reduced accumulation of AtpA (α) and AtpB (β), two core subunits of CF1αβ subcomplex of cpATPase, meanwhile, a severe decrease (ca. 41.7%) in cpATPase activity was observed in the yl1-1 mutant compared with the wild type. Furthermore, yeast two-hybrid and bimolecular fluorescence complementation assays revealed a specific interaction between YL1 and AtpB subunit of cpATPase. Taken together, our results suggest that YL1 is a plant lineage-specific auxiliary factor involved in the biogenesis of the cpATPase complex, possibly via interacting with the β-subunit. PMID:27585744

  5. Polymerase chain reaction-single strand conformation polymorphism analyses of nuclear and chloroplast DNA provide evidence for recombination, multiple introductions and nascent speciation in the Caulerpa taxifolia complex.

    PubMed

    Meusnier, I; Valero, M; Destombe, C; Godé, C; Desmarais, E; Bonhomme, F; Stam, W T; Olsen, J L

    2002-11-01

    Independent lines of evidence support an Australian origin for the Mediterranean populations of the tropical alga Caulerpa taxifolia. To complement previous biogeographical studies based on nuclear rDNA internal transcribed spacer (ITS), a new chloroplast marker was developed--the cp 16S rDNA intron-2. Sequence variability for both nuclear and chloroplast markers were assessed in 110 individuals using single strand conformation polymorphism. Comparison of intrapopulation genetic diversity between invasive Mediterranean and 'native' Australian populations revealed the occurrence of two divergent and widespread clades. The first clade grouped nontropical invasive populations with inshore-mainland populations from Australia, while the second clustered all offshore-island populations studied so far. Despite our finding of nine distinct nuclear and five distinct chloroplast profiles, a single nucleocytoplasmic combination was characteristic of the invasive populations and sexual reproduction was found to be very rare. C. taxifolia is clearly a complex of genetically and ecologically differentiated sibling species or subspecies.

  6. Complete Chloroplast Genome of Tanaecium tetragonolobum: The First Bignoniaceae Plastome

    PubMed Central

    Nazareno, Alison Gonçalves; Carlsen, Monica; Lohmann, Lúcia Garcez

    2015-01-01

    Bignoniaceae is a Pantropical plant family that is especially abundant in the Neotropics. Members of the Bignoniaceae are diverse in many ecosystems and represent key components of the Tropical flora. Despite the ecological importance of the Bignoniaceae and all the efforts to reconstruct the phylogeny of this group, whole chloroplast genome information has not yet been reported for any members of the family. Here, we report the complete chloroplast genome sequence of Tanaecium tetragonolobum (Jacq.) L.G. Lohmann, which was reconstructed using de novo and referenced-based assembly of single-end reads generated by shotgun sequencing of total genomic DNA in an Illumina platform. The gene order and organization of the chloroplast genome of T. tetragonolobum exhibits the general structure of flowering plants, and is similar to other Lamiales chloroplast genomes. The chloroplast genome of T. tetragonolobum is a circular molecule of 153,776 base pairs (bp) with a quadripartite structure containing two single copy regions, a large single copy region (LSC, 84,612 bp) and a small single copy region (SSC, 17,586 bp) separated by inverted repeat regions (IRs, 25,789 bp). In addition, the chloroplast genome of T. tetragonolobum has 38.3% GC content and includes 121 genes, of which 86 are protein-coding, 31 are transfer RNA, and four are ribosomal RNA. The chloroplast genome of T. tetragonolobum presents a total of 47 tandem repeats and 347 simple sequence repeats (SSRs) with mononucleotides being the most common and di-, tri-, tetra-, and hexanucleotides occurring with less frequency. The results obtained here were compared to other chloroplast genomes of Lamiales available to date, providing new insight into the evolution of chloroplast genomes within Lamiales. Overall, the evolutionary rates of genes in Lamiales are lineage-, locus-, and region-specific, indicating that the evolutionary pattern of nucleotide substitution in chloroplast genomes of flowering plants is complex

  7. The puzzle of chloroplast vesicle transport – involvement of GTPases

    PubMed Central

    Karim, Sazzad; Aronsson, Henrik

    2014-01-01

    In the cytosol of plant cells vesicle transport occurs via secretory pathways among the endoplasmic reticulum network, Golgi bodies, secretory granules, endosome, and plasma membrane. Three systems transfer lipids, proteins and other important molecules through aqueous spaces to membrane-enclosed compartments, via vesicles that bud from donor membranes, being coated and uncoated before tethered and fused with acceptor membranes. In addition, molecular, biochemical and ultrastructural evidence indicates presence of a vesicle transport system in chloroplasts. Little is known about the protein components of this system. However, as chloroplasts harbor the photosynthetic apparatus that ultimately supports most organisms on the planet, close attention to their pathways is warranted. This may also reveal novel diversification and/or distinct solutions to the problems posed by the targeted intra-cellular trafficking of important molecules. To date two homologs to well-known yeast cytosolic vesicle transport proteins, CPSAR1 and CPRabA5e (CP, chloroplast localized), have been shown to have roles in chloroplast vesicle transport, both being GTPases. Bioinformatic data indicate that several homologs of cytosolic vesicle transport system components are putatively chloroplast-localized and in addition other proteins have been implicated to participate in chloroplast vesicle transport, including vesicle-inducing protein in plastids 1, thylakoid formation 1, snowy cotyledon 2/cotyledon chloroplast biogenesis factor, curvature thylakoid 1 proteins, and a dynamin like GTPase FZO-like protein. Several putative potential cargo proteins have also been identified, including building blocks of the photosynthetic apparatus. Here we discuss details of the largely unknown putative chloroplast vesicle transport system, focusing on GTPase-related components. PMID:25295043

  8. Sequence evidence for the symbiotic origins of chloroplasts and mitochondria

    NASA Technical Reports Server (NTRS)

    George, D. G.; Hunt, L. T.; Dayhoff, M. O.

    1983-01-01

    The origin of mitochondria and chloroplasts is investigated on the basis of prokaryotic and early-eukaryotic evolutionary trees derived from protein and nucleic-acid sequences by the method of Dayhoff (1979). Trees for bacterial ferrodoxins, 5S ribosomal RNA, c-type cytochromes, the lipid-binding subunit of ATPase, and dihydrofolate reductase are presented and discussed. Good agreement among the trees is found, and it is argued that the mitochondria and chloroplasts evolved by multiple symbiotic events.

  9. [Chloroplast genetic engineering: a new approach in plant biotechnology].

    PubMed

    Su, Tao; Zhan, Ya-Guang; Han, Mei; Hao, Ai-Ping

    2005-07-01

    Chloroplast genetic engineering, offers several advantages over nuclear transformation, including high level of gene expression, increased biosafety, remedying some limitations associated with nuclear genetic transformation, such as gene silencing and the stability of transformed genes. It is now regarded as an attractive new transgenic technique and further development of biotechnology in agriculture. In this article we reviewed the characteristics, applications of chloroplast genetic engineering and its promising prospects were discussed.

  10. Sequence evidence for the symbiotic origins of chloroplasts and mitochondria

    NASA Technical Reports Server (NTRS)

    George, D. G.; Hunt, L. T.; Dayhoff, M. O.

    1983-01-01

    The origin of mitochondria and chloroplasts is investigated on the basis of prokaryotic and early-eukaryotic evolutionary trees derived from protein and nucleic-acid sequences by the method of Dayhoff (1979). Trees for bacterial ferrodoxins, 5S ribosomal RNA, c-type cytochromes, the lipid-binding subunit of ATPase, and dihydrofolate reductase are presented and discussed. Good agreement among the trees is found, and it is argued that the mitochondria and chloroplasts evolved by multiple symbiotic events.

  11. Chloroplast membrane transport: interplay of prokaryotic and eukaryotic traits.

    PubMed

    Vothknecht, Ute C; Soll, Jürgen

    2005-07-18

    Chloroplasts are specific plant organelles of prokaryotic origin. They are separated from the surrounding cell by a double membrane, which represents an effective barrier for the transport of metabolites and proteins. Specific transporters in the inner envelope membrane have been described, which facilitate the exchange of metabolites. In contrast, the outer envelope has been viewed for a long time as a molecular sieve that offers a mere size constriction to the passage of molecules. This view has been challenged lately, and a number of specific and regulated pore proteins of the outer envelope (OEPs) have been identified. These pores seem to have originated by adaptation of outer membrane proteins of the cyanobacterial ancestor of the chloroplast. In a similar fashion, the transport of proteins across the two envelope membranes is achieved by two hetero-oligomeric protein complexes called Toc (translocon in the outer envelope of chloroplasts) and Tic (translocon in the inner envelope of chloroplasts). The phylogenetic provenance of the translocon components is less clear, but at least the channel protein of the Toc translocon is of cyanobacterial origin. Characteristic of cyanobacteria and chloroplasts is furthermore a specialized internal membrane system, the thylakoids, on which the components of the photosynthetic machinery are located. Despite the importance of this membrane, very little is known about its phylogenetic origin or the manner of its synthesis. Vipp1 appears to be a ubiquitous component of thylakoid formation, while in chloroplasts of land plants, additionally a vesicle transport system of eukaryotic origin might be involved in this process.

  12. Role of mitochondria in sulfolipid biosynthesis by Euglena chloroplasts

    SciTech Connect

    Saidha, T.; Schiff, J.A.

    1987-04-01

    Sulfate activation occurs in Euglena mitochondria the authors now find that the sulfate activating enzymes are absent from Euglena chloroplasts. Cells of mutant W/sub 10/BSmL lacking plastids also lack detectable sulfolipid (SL) when grown on /sup 35/SO/sub 4//sup 2 -/ indicating that SL is absent from the mitochondria and is exclusively in the plastids. Plastids alone will convert /sup 35/S-cysteine to /sup 35/SL in the presence of ATP and Mg/sup 2 +/; light is stimulatory. Under similar conditions, chloroplasts and mitochondria incubated together convert /sup 35/SO/sub 4//sup 2 -/ to plastid-localized /sup 35/SL but either organelle incubated alone fails to effect this conversion. Unlabeled cysteine blocks SL labeling from sulfate in the mixed incubation; since cysteine is formed from sulfate by Euglena mitochrondria, cysteine (and other compounds) may move from the mitochondrion to the chloroplast to provide the sulfo group for SL formation. Although mitochondria form labeled protein from /sup 35/SO/sub 4//sup 2 -/ via cysteine, chloroplasts alone do not form labeled protein from /sup 35/SO/sub 4//sup 2 -/, ATP and Mg/sup 2 +/ in light or darkness; incubation of chloroplasts plus mitochondria under these conditions labels chloroplast protein.

  13. Chloroplasts continuously monitor photoreceptor signals during accumulation movement.

    PubMed

    Tsuboi, Hidenori; Wada, Masamitsu

    2013-07-01

    Under low light conditions, chloroplasts gather at a cell surface to maximize light absorption for efficient photosynthesis, which is called the accumulation response. Phototropin1 (phot1) and phototropin2 (phot2) were identified as blue light photoreceptors in the accumulation response that occurs in Arabidopsis thaliana and Adiantum capillus-veneris with neochrome1 (neo1) as a red light photoreceptor in A. capillus-veneris. However, the signal molecule that is emitted from the photoreceptors and transmitted to the chloroplasts is not known. To investigate this topic, the accumulation response was induced by partial cell irradiation with a microbeam of red, blue and far-red light in A. capillus-veneris gametophyte cells. Chloroplasts moved towards the irradiated region and were able to sense the signal as long as its signal flowed. The signal from neo1 had a longer life than the signal that came from phototropins. When two microbeams with the same wavelength and the same fluence rate were placed 20 μm apart from each other and were applied to a dark-adapted cell, chloroplasts at an equidistant position always moved towards the center (midpoint) of the two microbeams, but not towards either one. This result indicates that chloroplasts are detecting the concentration of the signal but not the direction of signal flow. Chloroplasts repeatedly move and stop at roughly 10 s intervals during the accumulation response, suggesting that they monitor the intermittent signal waves from photoreceptors.

  14. Interaction of actin and the chloroplast protein import apparatus.

    PubMed

    Jouhet, Juliette; Gray, John C

    2009-07-10

    Actin filaments are major components of the cytoskeleton and play numerous essential roles, including chloroplast positioning and plastid stromule movement, in plant cells. Actin is present in pea chloroplast envelope membrane preparations and is localized at the surface of the chloroplasts, as shown by agglutination of intact isolated chloroplasts by antibodies to actin. To identify chloroplast envelope proteins involved in actin binding, we have carried out actin co-immunoprecipitation and co-sedimentation experiments on detergent-solubilized pea chloroplast envelope membranes. Proteins co-immunoprecipitated with actin were identified by mass spectrometry and by Western blotting and included the Toc159, Toc75, Toc34, and Tic110 components of the TOC-TIC protein import apparatus. A direct interaction of actin with Escherichia coli-expressed Toc159, but not Toc33, was shown by co-sedimentation experiments, suggesting that Toc159 is the component of the TOC complex that interacts with actin on the cytosolic side of the outer envelope membrane. The physiological significance of this interaction is unknown, but it may play a role in the import of nuclear-encoded photosynthesis proteins.

  15. Speed of signal transfer in the chloroplast accumulation response.

    PubMed

    Tsuboi, Hidenori; Wada, Masamitsu

    2010-05-01

    Chloroplast photorelocation movement is important for plants to perform efficient photosynthesis. Phototropins were identified as blue-light receptors for chloroplast movement in Arabidopsis thaliana and in the fern Adiantum capillus-veneris, whereas neochrome functions as a dual red/blue light receptor in the latter. However, the signal transduction pathways involved in chloroplast movement remain to be clarified. To investigate the kinetic properties of signalling from these photoreceptors to the chloroplasts, we deduced the speed of signal transfer using Adiantum capillus-veneris gametophytes. When a region of dark-adapted gametophyte cells was subjected to microbeam irradiation, chloroplasts moved towards the irradiated area even in subsequent darkness. We therefore recorded the movement and calculated the speeds of signal transfer by time-lapse imaging. Movement speeds under red or blue light were similar, e.g., about 1.0 microm min(-1) in prothallial cells. However, speeds varied according to cell polarity in protonemal cells. The speed of signal transfer from the protonemal apex to the base was approximately 0.7 microm min(-1), but roughly 2.3 microm min(-1) in the opposite direction. The speed of signal transfer in Arabidopsis thaliana mesophyll cells was approximately 0.8 microm min(-1) by comparison. Surprisingly, chloroplasts located farthest away from the microbeam were found to move faster than those in close proximity to the site of irradiation both in Adiantum capillus-veneris and A. thaliana.

  16. Cell biology of the chloroplast symbiosis in sacoglossan sea slugs.

    PubMed

    Pierce, Sidney K; Curtis, Nicholas E

    2012-01-01

    Chloroplasts removed from their species of origin may survive for various periods and even photosynthesize in foreign cells. One of the best studied and impressively long, naturally occurring examples of chloroplast persistence, and function inside foreign cells are the algal chloroplasts taken up by specialized cells of certain sacoglossan sea slugs, a phenomenon called chloroplast symbiosis or kleptoplasty. Among sacoglossan species, kleptoplastic associations vary widely in length and function, with some animals immediately digesting chloroplasts, while others maintain functional plastids for over 10 months. Kleptoplasty is a complex process in long-term associations, and research on this topic has focused on a variety of aspects including plastid uptake and digestive physiology of the sea slugs, the longevity and maintenance of symbiotic associations, biochemical interactions between captured algal plastids and slug cells, and the role of horizontal gene transfers between the sea slug and algal food sources. Although the biochemistry underlying chloroplast symbiosis has been extensively examined in only a few slug species, it is obvious that the mechanisms vary from species to species. In this chapter, we examine those mechanisms from early discoveries to the most current research. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. Surveying the Oligomeric State of Arabidopsis thaliana Chloroplasts.

    PubMed

    Lundquist, Peter K; Mantegazza, Otho; Stefanski, Anja; Stühler, Kai; Weber, Andreas P M

    2017-01-09

    Blue native-PAGE (BN-PAGE) resolves protein complexes in their native state. When combined with immunoblotting, it can be used to identify the presence of high molecular weight complexes at high resolution for any protein, given a suitable antibody. To identify proteins in high molecular weight complexes on a large scale and to bypass the requirement for specific antibodies, we applied a tandem mass spectrometry (MS/MS) approach to BN-PAGE-resolved chloroplasts. Fractionation of the gel into six bands allowed identification and label-free quantification of 1000 chloroplast proteins with native molecular weight separation. Significantly, this approach achieves a depth of identification comparable with traditional shotgun proteomic analyses of chloroplasts, indicating much of the known chloroplast proteome is amenable to MS/MS identification under our fractionation scheme. By limiting the number of fractionation bands to six, we facilitate scaled-up comparative analyses, as we demonstrate with the reticulata chloroplast mutant displaying a reticulated leaf phenotype. Our comparative proteomics approach identified a candidate interacting protein of RETICULATA as well as effects on lipid remodeling proteins, amino acid metabolic enzymes, and plastid division machinery. We additionally highlight selected proteins from each sub-compartment of the chloroplast that provide novel insight on known or hypothesized protein complexes to further illustrate the utility of this approach. Our results demonstrate the high sensitivity and reproducibility of this technique, which is anticipated to be widely adaptable to other sub-cellular compartments.

  18. Energetic and regulatory role of proton potential in chloroplasts.

    PubMed

    Tikhonov, A N

    2012-09-01

    The review focuses on the energetic and regulatory role of proton potential in the activity of chloroplasts, the light energy-converting organelles of plant cells. Mechanisms of generation of the transmembrane difference of electrochemical potentials of hydrogen ions (Δµ(~)(H+)) in the chloroplast thylakoid membranes are considered. Methods for measuring the intrathylakoid pH in chloroplasts are described. It is shown that under conditions of phosphorylation in chloroplasts, the pH of the intrathylakoid space decreases moderately (pH(in) ≥ 6.0-6.2, at the stroma pH(out) ≈ 7.8-8.0), with a corresponding concentration component of Δµ(~)(H+) equal to ΔpH ≤ 1.6-2.0. On analyzing the energy and structural features of ATP synthase of chloroplasts, we conclude that the energy stored as the concentration component of the proton potential ΔpH is sufficient to sustain ATP synthesis. The mechanisms of pH-dependent regulation of electron transport in chloroplasts (photosynthetic control of electron transport, enhancement of non-photochemical quenching of chlorophyll excitation in the light-harvesting antenna, light-induced activation of the Calvin-Benson cycle reactions, activation of ATP synthase) are considered briefly.

  19. Novel mechanisms for maturation of chloroplast transfer RNA precursors

    PubMed Central

    Wang, Ming Jing; Davis, N. Wayne; Gegenheimer, Peter

    1988-01-01

    Despite the prokaryotic origins of chloroplasts, a plant chloroplast tRNA precursor is processed in a homologous in vitro system by a pathway distinct from that observed in Escherichia coli, but identical to that utilized for maturation of nuclear pre-tRNAs. The mature tRNA 5' terminus is generated by the site-specific endonucleolytic cleavage of an RNase P (or P-type) activity. The 3' end is likewise produced by a single precise endonucleolytic cut at the 3' terminus of the encoded tRNA domain. This is the first complete structural characterization of an organellar tRNA processing system using a homologous substrate. In contrast to eubacterial RNase P, chloroplast RNase P does not appear to contain an RNA subunit. The chloroplast activity bands with bulk protein at 1.28 g/ml in CsCI density gradients, whereas E.coli RNase P bands as ribonucleoprotein at 1.73 g/ml. Chloroplast RNase P activity survives treatment with micrococcal nuclease (MN) at levels 10- to 100-fold higher than those required to totally inactivate the E.coli enzyme. The chloroplast system is sensitive to a suppression of tRNA processing, caused by binding of inactive MN to pre-tRNA substrate, which is readily overcome by addition of carrier RNA to the assay. Images PMID:16453848

  20. Amino acid incorporation by ribosomes and polyribosomes from wheat chloroplasts

    PubMed Central

    Hadziyev, D.; Zalik, Saul

    1970-01-01

    Sucrose-gradient and analytical ultracentrifugation showed that chloroplast polyribosomes from 4-day-old seedlings had mono-, di-, tri-, tetra- and traces of penta-ribosomes, in contrast with those from 7-day-old seedlings in which only the mono-, di- and traces of tri-ribosomes were present. Without Mg2+ the polyribosomes dissociated into ribosomal subunits. The rate of l-[U-14C]phenylalanine incorporation was threefold greater for preparations from 4- than from 7-day-old seedlings. Incorporation by the latter was stimulated by polyuridylic acid. The rates of incorporation were similar whether the reaction mixture contained chloroplast or wheat-germ transfer RNA and amino acid synthetases purified on methylated albumin-on-kieselguhr and Sephadex G-75 columns respectively. The cofactor requirement was the same as for isolated intact chloroplasts. Osmotic rupture of chloroplasts with and without Triton X-100 revealed the presence of free and bound ribosomes. Free single ribosomes isolated by osmotic shrinkage or prepared by pancreatic ribonuclease digestion of chloroplast polyribosomes had negligible incorporation activity. This activity was increased by washing or by polyuridylic acid, but was still only a fraction of that given by polyribosomes. A comparison of incorporation activity of chloroplast polyribosomes with those from the surrounding cytoplasm showed the former to be 20 times more active. ImagesFig. 1.Fig. 9. PMID:5411422

  1. Regulation of Chloroplast Photosynthetic Activity by Exogenous Magnesium 1

    PubMed Central

    Huber, Steven C.

    1978-01-01

    Magnesium was most inhibitory to photosynthetic reactions by intact chloroplasts when the magnesium was added in the dark before illumination. Two millimolar MgCl2, added in the dark, inhibited CO2-dependent O2 evolution by Hordeum vulgare L. and Spinacia oleracea L. (C3 plants) chloroplasts 70 to 100% and inhibited (pyruvate + oxaloacetate)-dependent O2 evolution by Digitaria sanguinalis L. (C4 plant) mesophyll chloroplasts from 80 to 100%. When Mg2+ was added in the light, O2 evolution was reduced only slightly. O2 evolution in the presence of phosphoglycerate was less sensitive to Mg2+ inhibition than was CO2-dependent O2 evolution. Magnesium prevented the light activation of several photosynthetic enzymes. Two millimolar Mg2+ blocked the light activation of NADP-malate dehydrogenase in D. sanguinalis mesophyll chloroplasts, and the light activation of phosphoribulokinase, NADP-linked glyceraldehyde-3-phosphate dehydrogenase, and fructose 1,6-diphosphatase in barley chloroplasts. The results suggest that Mg2+ inhibits chloroplast photosynthesis by preventing the light activation of certain enzymes. PMID:16660509

  2. Interspecific chloroplast recombination in a Nicotiana somatic hybrid.

    PubMed

    Medgyesy, P; Fejes, E; Maliga, P

    1985-10-01

    Genetic recombination between chloroplasts of two flowering plant species, Nicotiana tabacum and Nicotiana plumbaginifolia, after somatic cell fusion is described. The parental lines differed in three cytoplasmic genetic markers. The N. tabacum mutant SR1-A15 was streptomycin-resistant, defective in chloroplast greening, and lincomycin-sensitive. The N. plumbaginifolia mutant LR400 was streptomycin-sensitive, normal green, and lincomycin-resistant. Streptomycin-resistant clones in cell culture are identified by their ability to form a green callus on a selective medium. Streptomycin resistance in the SR1-A15 mutant could not be expressed due to defective chloroplasts. Protoplasts of the two species were fused, and calli grown from the fused population were screened for the expression of streptomycin resistance from the SR1-A15 line as the result of interspecific chloroplast recombination. A somatic hybrid, pt14, expressed a new combination of the cytoplasmic genetic markers. In the pt14 chloroplast genome three N. tabacum and four N. plumbaginifolia parent specific restriction sites have been identified, indicating that the pt14 chloroplast genome contains at least six recombination sites.

  3. Transmission of paternal chloroplasts in tobacco (Nicotiana tabacum).

    PubMed

    Horlow, C; Goujaud, J; Lépingle, A; Missonier, C; Bourgin, J P

    1990-09-01

    Medgyesy et al. (1986, Mol. Gen. Genet. 204, 195-198) have described in Nicotiana plumbaginifolia and in an interspecific cross involving N. plumbaginifolia and N. tabacum a procedure for selecting cell lines derived from seedlings carrying paternal chloroplasts by taking advantage of a plastid-encoded mutation which confers resistance to streptomycin. We have extended their demonstration of occasional transmission of chloroplasts through pollen to the case of an intraspecific cross in N. tabacum. The line used as maternal parent, ITB19(sua), displayed a cytoplasmic male sterility due to the presence of a cytoplasm originating from N. suaveolens. The line used as paternal parent, SR1, was fertile and possessed mutant chloroplasts conferring resistance to streptomycin. From cell lines derived from 204 seedlings, three were regenerated into streptomycin-resistant buds. The plants derived from these three clones were male-sterile. Their progeny, after crossing with a wild type tobacco line, XHFD8, was resistant to streptomycin. Tests of resistance of the seedlings to tentoxin and restriction analyses of the chloroplast DNA indicated that two clones still had the maternal chloroplasts and were thus probably new streptomycin-resistant mutants, whereas the third one had acquired the chloroplasts of the paternal parent, but had retained the mitochondria of the maternal parent.

  4. Evidence that sigma factors are components of chloroplast RNA polymerase.

    PubMed Central

    Troxler, R F; Zhang, F; Hu, J; Bogorad, L

    1994-01-01

    Plastid genes are transcribed by DNA-dependent RNA polymerase(s), which have been incompletely characterized and have been examined in a limited number of species. Plastid genomes contain rpoA, rpoB, rpoC1, and rpoC2 coding for alpha, beta, beta', and beta" RNA polymerase subunits that are homologous to the alpha, beta, and beta' subunits that constitute the core moiety of RNA polymerase in bacteria. However, genes with homology to sigma subunits in bacteria have not been found in plastid genomes. An antibody directed against the principal sigma subunit of RNA polymerase from the cyanobacterium Anabaena sp. PCC 7120 was used to probe western blots of purified chloroplast RNA polymerase from maize, rice, Chlamydomonas reinhardtii, and Cyanidium caldarium. Chloroplast RNA polymerase from maize and rice contained an immunoreactive 64-kD protein. Chloroplast RNA polymerase from C. reinhardtii contained immunoreactive 100- and 82-kD proteins, and chloroplast RNA polymerase from C. caldarium contained an immunoreactive 32-kD protein. The elution profile of enzyme activity of both algal chloroplast RNA polymerases coeluted from DEAE with the respective immunoreactive proteins, indicating that they are components of the enzyme. These results provide immunological evidence for sigma-like factors in chloroplast RNA polymerase in higher plants and algae. PMID:8159791

  5. Ferns, mosses and liverworts as model systems for light-mediated chloroplast movements.

    PubMed

    Suetsugu, Noriyuki; Higa, Takeshi; Wada, Masamitsu

    2016-11-17

    Light-induced chloroplast movement is found in most plant species, including algae and land plants. In land plants with multiple small chloroplasts, under weak light conditions, the chloroplasts move towards the light and accumulate on the periclinal cell walls to efficiently perceive light for photosynthesis (the accumulation response). Under strong light conditions, chloroplasts escape from light to avoid photodamage (the avoidance response). In most plant species, blue light induces chloroplast movement, and phototropin receptor kinases are the blue light receptors. Molecular mechanisms for photoreceptors, signal transduction and chloroplast motility systems are being studied using the model plant Arabidopsis thaliana. However, to further understand the molecular mechanisms and evolutionary history of chloroplast movement in green plants, analyses using other plant systems are required. Here, we review recent works on chloroplast movement in green algae, liverwort, mosses and ferns that provide new insights on chloroplast movement.

  6. Chloroplast microsatellite markers for Pseudotaxus chienii developed from the whole chloroplast genome of Taxus chinensis var. mairei (Taxaceae)1

    PubMed Central

    Deng, Qi; Zhang, Hanrui; He, Yipeng; Wang, Ting; Su, Yingjuan

    2017-01-01

    Premise of the study: Pseudotaxus chienii (Taxaceae) is an old rare species endemic to China that has adapted well to ecological heterogeneity with high genetic diversity in its nuclear genome. However, the genetic variation in its chloroplast genome is unknown. Methods and Results: Eighteen chloroplast microsatellite markers (cpSSRs) were developed from the whole chloroplast genome of Taxus chinensis var. mairei and successfully amplified in four P. chienii populations and one T. chinensis var. mairei population. Of these loci, 10 were polymorphic in P. chienii, whereas six were polymorphic in T. chinensis var. mairei. The unbiased haploid diversity per locus ranged from 0.000 to 0.641 and 0.000 to 0.545 for P. chienii and T. chinensis var. mairei, respectively. Conclusions: The 18 cpSSRs will be used to further investigate the chloroplast genetic structure and adaptive evolution in P. chienii populations. PMID:28337394

  7. Proteomic analysis of chloroplast biogenesis (clb) mutants uncovers novel proteins potentially involved in the development of Arabidopsis thaliana chloroplasts.

    PubMed

    de Luna-Valdez, L A; Martínez-Batallar, A G; Hernández-Ortiz, M; Encarnación-Guevara, S; Ramos-Vega, M; López-Bucio, J S; León, P; Guevara-García, A A

    2014-12-05

    Plant cells outstand for their ability to generate biomass from inorganic sources, this phenomenon takes place within the chloroplasts. The enzymatic machinery and developmental processes of chloroplasts have been subject of research for several decades, and this has resulted in the identification of a plethora of proteins that are essential for their development and function. Mutant lines for the genes that code for those proteins, often display pigment-accumulation defects (e.g., albino phenotypes). Here, we present a comparative proteomic analysis of four chloroplast-biogenesis affected mutants (cla1-1, clb2, clb5, clb19) aiming to identify novel proteins involved in the regulation of chloroplast development in Arabidopsis thaliana. We performed 2D-PAGE separation of the protein samples. These samples were then analyzed by computational processing of gel images in order to select protein spots with abundance shifts of at least twofold, statistically significant according to Student's t-test (P<0.01). These spots were subjected to MALDI-TOF mass-spectrometry for protein identification. This process resulted in the discovery of three novel proteins potentially involved in the development of A. thaliana chloroplasts, as their associated mutant lines segregate pigment-deficient plants with abnormal chloroplasts, and altered mRNA accumulation of chloroplast-development marker genes. This report highlights the potential of using a comparative proteomics strategy for the study of biological processes. Particularly, we compared the proteomes of wild-type seedlings and four mutant lines of A. thaliana affected in chloroplast biogenesis. From this proteomic analysis it was possible to detect common mechanisms in the mutants to respond to stress and cope with heterotrophy. Notably, it was possible to identify three novel proteins potentially involved in the development or functioning of chloroplasts, also it was demonstrated that plants annotated to carry T-DNA insertions

  8. Population Genetic Structure and Phylogeography of Camellia flavida (Theaceae) Based on Chloroplast and Nuclear DNA Sequences

    PubMed Central

    Wei, Su-Juan; Lu, Yong-Bin; Ye, Quan-Qing; Tang, Shao-Qing

    2017-01-01

    Camellia flavida is an endangered species of yellow camellia growing in limestone mountains in southwest China. The current classification of C. flavida into two varieties, var. flavida and var. patens, is controversial. We conducted a genetic analysis of C. flavida to determine its taxonomic structure. A total of 188 individual plants from 20 populations across the entire distribution range in southwest China were analyzed using two DNA fragments: a chloroplast DNA fragment from the small single copy region and a single-copy nuclear gene called phenylalanine ammonia-lyase (PAL). Sequences from both chloroplast and nuclear DNA were highly diverse; with high levels of genetic differentiation and restricted gene flow. This result can be attributed to the high habitat heterogeneity in limestone karst, which isolates C. flavida populations from each other. Our nuclear DNA results demonstrate that there are three differentiated groups within C. flavida: var. flavida 1, var. flavida 2, and var. patens. These genetic groupings are consistent with the morphological characteristics of the plants. We suggest that the samples included in this study constitute three taxa and the var. flavida 2 group is the genuine C. flavida. The three groups should be recognized as three management units for conservation concerns. PMID:28579991

  9. Rapid severing and motility of chloroplast-actin filaments are required for the chloroplast avoidance response in Arabidopsis.

    PubMed

    Kong, Sam-Geun; Arai, Yoshiyuki; Suetsugu, Noriyuki; Yanagida, Toshio; Wada, Masamitsu

    2013-02-01

    Phototropins (phot1 and phot2 in Arabidopsis thaliana) relay blue light intensity information to the chloroplasts, which move toward weak light (the accumulation response) and away from strong light (the avoidance response). Chloroplast-actin (cp-actin) filaments are vital for mediating these chloroplast photorelocation movements. In this report, we examine in detail the cp-actin filament dynamics by which the chloroplast avoidance response is regulated. Although stochastic dynamics of cortical actin fragments are observed on the chloroplasts, the basic mechanisms underlying the disappearance (including severing and turnover) of the cp-actin filaments are regulated differently from those of cortical actin filaments. phot2 plays a pivotal role in the strong blue light-induced severing and random motility of cp-actin filaments, processes that are therefore essential for asymmetric cp-actin formation for the avoidance response. In addition, phot2 functions in the bundling of cp-actin filaments that is induced by dark incubation. By contrast, the function of phot1 is dispensable for these responses. Our findings suggest that phot2 is the primary photoreceptor involved in the rapid reorganization of cp-actin filaments that allows chloroplasts to change direction rapidly and control the velocity of the avoidance movement according to the light's intensity and position.

  10. Evidence for chloroplastic succinate dehydrogenase participating in the chloroplastic respiratory and photosynthetic electron transport chains of Chlamydomonas reinhardtii

    SciTech Connect

    Willeford, K.O.; Gombos, Z.; Gibbs, M. )

    1989-07-01

    A method for isolating intact chloroplasts from Chlamydomonas reinhardtii F-60 was developed from the Klein, Chen, Gibbs, Platt-Aloia procedure. Protoplasts, generated by treatment with autolysine, were lysed with a solution of digitonin and fractionated on Percoll step gradients. The chloroplasts were assessed to be 90% intact (ferricyanide assay) and free from cytoplasmic contamination (NADP isocitrate dehydrogenase activity) and to range from 2 to 5% in mitochondrial contamination (cytochrome c oxidase activity). About 25% of the cellular succinate dehydrogenase activity (21.6 micromoles per milligram chlorophyll per hour, as determined enzymically) was placed within the chloroplast. Chloroplastic succinate dehydrogenase had a K{sub m} for succinate of 0.55 millimolar and was associated with the thylakoidal material derived from the intact chloroplasts. This same thylakoidal material, with an enzymic assay of 21.6 micromoles per milligram chlorophyll per hour was able to initiate a light-dependent uptake of oxygen at a rate of 16.4 micromoles per milligram chlorophyll per hour when supplied with succinate and methyl viologen. Malonate was an apparent competitive inhibitor of this reaction. The succinate dehydrogenase activity present in the chloroplast was sufficient to account for the photoanaerobic rate of acetate dissimilation in H{sub 2} adapted Chlamydomonas.

  11. Genetic diversity and gene flow in a Caribbean tree Pterocarpus officinalis Jacq.: a study based on chloroplast and nuclear microsatellites.

    PubMed

    Muller, F; Voccia, M; Bâ, A; Bouvet, J-M

    2009-03-01

    We analysed the molecular diversity of Pterocarpus officinalis, a tree species distributed in Caribbean islands, South and Central America to quantify the genetic variation within island, to assess the pattern of differentiation and infer levels of gene flow; with the overall goal of defining a strategy of conservation. Two hundred two individuals of 9 populations were analysed using three chloroplast and six nuclear microsatellite markers. The observed heterozygosity varied markedly among the populations for nuclear (H(Onuc )= 0.20-0.50) and chloroplast microsatellites (H (cp )= 0.22-0.68). The continental population from French Guyana showed a higher value of H(Onuc) than island populations, and the differences were significant in some cases. The fixation index F (IS) ranged from -0.043 to 0.368; a significant heterozygote deficit was detected in 7 populations. The heterozygosity excess method suggested that two populations in Guadeloupe have undergone a recent bottleneck. Global and pairwise F (ST) were high for both nuclear (F(STnuc )= 0.29) and chloroplast microsatellites (F(STcp )= 0.58). The neighbour-joining tree based on both markers, presented a differentiation pattern that can be explained by the seed dispersal by flotation and marine stream. The comparison of Bayesian approach and the method based on allelic frequency demonstrate a very limited number of migrants between populations.

  12. Dimorphic chloroplasts in the epidermis of Podostemoideae, a subfamily of the unique aquatic angiosperm family Podostemaceae.

    PubMed

    Fujinami, Rieko; Yoshihama, Isao; Imaichi, Ryoko

    2011-09-01

    Plants of the Podostemoideae, a subfamily of the unique aquatic angiosperm family Podostemaceae, which are found in rapids and waterfalls of the tropics and subtropics, have two different sizes of chloroplasts in their epidermis. These small and large chloroplasts are located separately in each epidermal cell along its upper and inner tangential walls, respectively. This is the first case of the chloroplast dimorphism in a single epidermal cell of angiosperms. While the large chloroplasts have well developed starch grains, the small chloroplasts have a normal granal ultrastructure but very few starch grains. This suggests that the small chloroplasts mainly function in CO(2) uptake for photosynthesis from torrential water.

  13. Using stable isotopes to characterize differential depth of water uptake based on environmental conditions in perennial biofuel and traditional annual crops

    NASA Astrophysics Data System (ADS)

    Miller, J. N.; Nystrom, R.; Bernacchi, C.

    2013-12-01

    Global climate change related to fossil fuel consumption coupled with the necessity for secure, cost-effective, and renewable domestic energy is continuing to drive the development of a bioenergy industry. Numerous second-generation biofuel crops have been identified that hold promise as sustainable feedstocks for the industry, including perennial grasses that utilize the highly water and energy efficient C4 photosynthetic pathway. Among the perennial grasses, miscanthus (Miscanthus × giganteus) and switchgrass (Panicum virgatum) stand out as having high biomass, minimal maintenance, low nutrient input requirements, and positive environmental benefits. These grasses are able to withstand a wide range of growing season temperatures and precipitation regimes, particularly in reference to the annual row crops that they are likely to replace. During the drought of 2012 traditional row crops suffered major reductions in yield whereas the perennial grasses retained relatively high biomass yields. We hypothesize that this is due to the ability of the perennial grasses to access water from deeper soil water relative to the annual row crops. To test this hypothesis, we use isotopic techniques to determine the soil depth from which the various species obtain water. Data from summer 2013 suggests that the perennial grasses preferentially use surface water when available but can extract water from depths that the annual row crops are unable to reach. These results indicate that perennial grasses, with deeper roots, will likely sustain growth under conditions when annual row crops are unable.

  14. The Physcomitrella patens Chloroplast Proteome Changes in Response to Protoplastation

    PubMed Central

    Fesenko, Igor; Seredina, Anna; Arapidi, Georgij; Ptushenko, Vasily; Urban, Anatoly; Butenko, Ivan; Kovalchuk, Sergey; Babalyan, Konstantin; Knyazev, Andrey; Khazigaleeva, Regina; Pushkova, Elena; Anikanov, Nikolai; Ivanov, Vadim; Govorun, Vadim M.

    2016-01-01

    Plant protoplasts are widely used for genetic manipulation and functional studies in transient expression systems. However, little is known about the molecular pathways involved in a cell response to the combined stress factors resulted from protoplast generation. Plants often face more than one type of stress at a time, and how plants respond to combined stress factors is therefore of great interest. Here, we used protoplasts of the moss Physcomitrella patens as a model to study the effects of short-term stress on the chloroplast proteome. Using label-free comparative quantitative proteomic analysis (SWATH-MS), we quantified 479 chloroplast proteins, 219 of which showed a more than 1.4-fold change in abundance in protoplasts. We additionally quantified 1451 chloroplast proteins using emPAI. We observed degradation of a significant portion of the chloroplast proteome following the first hour of stress imposed by the protoplast isolation process. Electron-transport chain (ETC) components underwent the heaviest degradation, resulting in the decline of photosynthetic activity. We also compared the proteome changes to those in the transcriptional level of nuclear-encoded chloroplast genes. Globally, the levels of the quantified proteins and their corresponding mRNAs showed limited correlation. Genes involved in the biosynthesis of chlorophyll and components of the outer chloroplast membrane showed decreases in both transcript and protein abundance. However, proteins like dehydroascorbate reductase 1 and 2-cys peroxiredoxin B responsible for ROS detoxification increased in abundance. Further, genes such as thylakoid ascorbate peroxidase were induced at the transcriptional level but down-regulated at the proteomic level. Together, our results demonstrate that the initial chloroplast reaction to stress is due changes at the proteomic level. PMID:27867392

  15. Chloroplast DNA Sequence Homologies among Vascular Plants 1

    PubMed Central

    Lamppa, Gayle K.; Bendich, Arnold J.

    1979-01-01

    The extent of sequence conservation in the chloroplast genome of higher plants has been investigated. Supercoiled chloroplast DNA, prepared from pea seedlings, was labeled in vitro and used as a probe in reassociation experiments with a high concentration of total DNAs extracted from several angiosperms, gymnosperms, and lower vascular plants. In each case the probe reassociation was accelerated, demonstrating that some chloroplast sequences have been highly conserved throughout the evolution of vascular plants. Only among the flowering plants were distinct levels of cross-reaction with the pea chloroplast probe evident; broad bean and barley exhibited the highest and lowest levels, respectively. With the hydroxylapatite assay these levels decreased with a decrease in probe fragment length (from 1,860 to 735 bases), indicating that many conserved sequences in the chloroplast genome are separated by divergent sequences on a rather fine scale. Despite differences observed in levels of homology with the hydroxylapatite assay, S1 nuclease analysis of heteroduplexes showed that outside of the pea family the extent of sequence relatedness between the probe and various heterologous DNAs is approximately the same: 30%. In our interpretation, the fundamental changes in the chloroplast genome during angiosperm evolution involved the rearrangement of this 30% with respect to the more rapidly changing sequences of the genome. These rearrangements may have been more extensive in dicotyledons than in monocotyledons. We have estimated the amount of conserved and divergent DNA interspersed between one another. From the reassociation experiments, determinations were made of the percentage of chloroplast DNA in total DNA extracts from different higher plants; this value remained relatively constant when compared with the large variation in the diploid genome size of the plants. PMID:16660786

  16. Photonic multilayer structure of Begonia chloroplasts enhances photosynthetic efficiency.

    PubMed

    Jacobs, Matthew; Lopez-Garcia, Martin; Phrathep, O-Phart; Lawson, Tracy; Oulton, Ruth; Whitney, Heather M

    2016-10-24

    Enhanced light harvesting is an area of interest for optimizing both natural photosynthesis and artificial solar energy capture(1,2). Iridescence has been shown to exist widely and in diverse forms in plants and other photosynthetic organisms and symbioses(3,4), but there has yet to be any direct link demonstrated between iridescence and photosynthesis. Here we show that epidermal chloroplasts, also known as iridoplasts, in shade-dwelling species of Begonia(5), notable for their brilliant blue iridescence, have a photonic crystal structure formed from a periodic arrangement of the light-absorbing thylakoid tissue itself. This structure enhances photosynthesis in two ways: by increasing light capture at the predominantly green wavelengths available in shade conditions, and by directly enhancing quantum yield by 5-10% under low-light conditions. These findings together imply that the iridoplast is a highly modified chloroplast structure adapted to make best use of the extremely low-light conditions in the tropical forest understorey in which it is found(5,6). A phylogenetically diverse range of shade-dwelling plant species has been found to produce similarly structured chloroplasts(7-9), suggesting that the ability to produce chloroplasts whose membranes are organized as a multilayer with photonic properties may be widespread. In fact, given the well-established diversity and plasticity of chloroplasts(10,11), our results imply that photonic effects may be important even in plants that do not show any obvious signs of iridescence to the naked eye but where a highly ordered chloroplast structure may present a clear blue reflectance at the microscale. Chloroplasts are generally thought of as purely photochemical; we suggest that one should also think of them as a photonic structure with a complex interplay between control of light propagation, light capture and photochemistry.

  17. Eukaryotic Hsp70 chaperones in the intermembrane space of chloroplasts.

    PubMed

    Bionda, Tihana; Gross, Lucia E; Becker, Thomas; Papasotiriou, Dimitrios G; Leisegang, Matthias S; Karas, Michael; Schleiff, Enrico

    2016-03-01

    Multiple eukaryotic Hsp70 typically localized in the cytoplasm are also distributed to the intermembrane space of chloroplasts and might thereby represent the missing link in energizing protein translocation. Protein translocation into organelles is a central cellular process that is tightly regulated. It depends on signals within the preprotein and on molecular machines catalyzing the process. Molecular chaperones participate in transport and translocation of preproteins into organelles to control folding and to provide energy for the individual steps. While most of the processes are explored and the components are identified, the transfer of preproteins into and across the intermembrane space of chloroplasts is not yet understood. The existence of an energy source in this compartment is discussed, because the required transit peptide length for successful translocation into chloroplasts is shorter than that found for mitochondria where energy is provided exclusively by matrix chaperones. Furthermore, a cytosolic-type Hsp70 homologue was proposed as component of the chloroplast translocon in the intermembrane space energizing the initial translocation. The molecular identity of such intermembrane space localized Hsp70 remained unknown, which led to a controversy concerning its existence. We identified multiple cytosolic Hsp70s by mass spectrometry on isolated, thermolysin-treated Medicago sativa chloroplasts. The localization of these Hsp70s of M. sativa or Arabidopsis thaliana in the intermembrane space was confirmed by a self-assembly GFP-based in vivo system. The localization of cytosolic Hsp70s in the stroma of chloroplasts or different mitochondrial compartments could not be observed. Similarly, we could not identify any cytosolic Hsp90 in the intermembrane space of chloroplast. With respect to our results we discuss the possible targeting and function of the Hsp70 found in the intermembrane space.

  18. Analysis of Protein Interactions at Native Chloroplast Membranes by Ellipsometry

    PubMed Central

    Kriechbaumer, Verena; Nabok, Alexei; Mustafa, Mohd K.; Al-Ammar, Rukaiah; Tsargorodskaya, Anna; Smith, David P.; Abell, Ben M.

    2012-01-01

    Membrane bound receptors play vital roles in cell signaling, and are the target for many drugs, yet their interactions with ligands are difficult to study by conventional techniques due to the technical difficulty of monitoring these interactions in lipid environments. In particular, the ability to analyse the behaviour of membrane proteins in their native membrane environment is limited. Here, we have developed a quantitative approach to detect specific interactions between low-abundance chaperone receptors within native chloroplast membranes and their soluble chaperone partners. Langmuir-Schaefer film deposition was used to deposit native chloroplasts onto gold-coated glass slides, and interactions between the molecular chaperones Hsp70 and Hsp90 and their receptors in the chloroplast membranes were detected and quantified by total internal reflection ellipsometry (TIRE). We show that native chloroplast membranes deposited on gold-coated glass slides using Langmuir-Schaefer films retain functional receptors capable of binding chaperones with high specificity and affinity. Taking into account the low chaperone receptor abundance in native membranes, these binding properties are consistent with data generated using soluble forms of the chloroplast chaperone receptors, OEP61 and Toc64. Therefore, we conclude that chloroplasts have the capacity to selectively bind chaperones, consistent with the notion that chaperones play an important role in protein targeting to chloroplasts. Importantly, this method of monitoring by TIRE does not require any protein labelling. This novel combination of techniques should be applicable to a wide variety of membranes and membrane protein receptors, thus presenting the opportunity to quantify protein interactions involved in fundamental cellular processes, and to screen for drugs that target membrane proteins. PMID:22479632

  19. Transplastomic integration of a cyanobacterial bicarbonate transporter into tobacco chloroplasts.

    PubMed

    Pengelly, J J L; Förster, B; von Caemmerer, S; Badger, M R; Price, G D; Whitney, S M

    2014-07-01

    Improving global yields of agricultural crops is a complex challenge with evidence indicating benefits in productivity are achieved by enhancing photosynthetic carbon assimilation. Towards improving rates of CO2 capture within leaf chloroplasts, this study shows the versatility of plastome transformation for expressing the Synechococcus PCC7002 BicA bicarbonate transporter within tobacco plastids. Fractionation of chloroplast membranes from transplastomic tob(BicA) lines showed that ~75% of the BicA localized to the thylakoid membranes and ~25% to the chloroplast envelope. BicA levels were highest in young emerging tob(BicA) leaves (0.12 μmol m(-2), ≈7mg m(-2)) accounting for ~0.1% (w/w) of the leaf protein. In these leaves, the molar amount of BicA was 16-fold lower than the abundant thylakoid photosystem II D1 protein (~1.9 μmol m(-2)) which was comparable to the 9:1 molar ratio of D1:BicA measured in air-grown Synechococcus PCC7002 cells. The BicA produced had no discernible effect on chloroplast ultrastructure, photosynthetic CO2-assimilation rates, carbon isotope discrimination, or growth of the tob(BicA) plants, implying that the bicarbonate transporter had little or no activity. These findings demonstrate the utility of plastome transformation for targeting bicarbonate transporter proteins into the chloroplast membranes without impeding growth or plastid ultrastructure. This study establishes the span of experimental measurements required to verify heterologous bicarbonate transporter function and location in chloroplasts and underscores the need for more detailed understanding of BicA structure and function to identify solutions for enabling its activation and operation in leaf chloroplasts.

  20. Chloroplast genome structure in Ilex (Aquifoliaceae)

    PubMed Central

    Yao, Xin; Tan, Yun-Hong; Liu, Ying-Ying; Song, Yu; Yang, Jun-Bo; Corlett, Richard T.

    2016-01-01

    Aquifoliaceae is the largest family in the campanulid order Aquifoliales. It consists of a single genus, Ilex, the hollies, which is the largest woody dioecious genus in the angiosperms. Most species are in East Asia or South America. The taxonomy and evolutionary history remain unclear due to the lack of a robust species-level phylogeny. We produced the first complete chloroplast genomes in this family, including seven Ilex species, by Illumina sequencing of long-range PCR products and subsequent reference-guided de novo assembly. These genomes have a typical bicyclic structure with a conserved genome arrangement and moderate divergence. The total length is 157,741 bp and there is one large single-copy region (LSC) with 87,109 bp, one small single-copy with 18,436 bp, and a pair of inverted repeat regions (IR) with 52,196 bp. A total of 144 genes were identified, including 96 protein-coding genes, 40 tRNA and 8 rRNA. Thirty-four repetitive sequences were identified in Ilex pubescens, with lengths >14 bp and identity >90%, and 11 divergence hotspot regions that could be targeted for phylogenetic markers. This study will contribute to improved resolution of deep branches of the Ilex phylogeny and facilitate identification of Ilex species. PMID:27378489

  1. Chloroplast genome structure in Ilex (Aquifoliaceae).

    PubMed

    Yao, Xin; Tan, Yun-Hong; Liu, Ying-Ying; Song, Yu; Yang, Jun-Bo; Corlett, Richard T

    2016-07-05

    Aquifoliaceae is the largest family in the campanulid order Aquifoliales. It consists of a single genus, Ilex, the hollies, which is the largest woody dioecious genus in the angiosperms. Most species are in East Asia or South America. The taxonomy and evolutionary history remain unclear due to the lack of a robust species-level phylogeny. We produced the first complete chloroplast genomes in this family, including seven Ilex species, by Illumina sequencing of long-range PCR products and subsequent reference-guided de novo assembly. These genomes have a typical bicyclic structure with a conserved genome arrangement and moderate divergence. The total length is 157,741 bp and there is one large single-copy region (LSC) with 87,109 bp, one small single-copy with 18,436 bp, and a pair of inverted repeat regions (IR) with 52,196 bp. A total of 144 genes were identified, including 96 protein-coding genes, 40 tRNA and 8 rRNA. Thirty-four repetitive sequences were identified in Ilex pubescens, with lengths >14 bp and identity >90%, and 11 divergence hotspot regions that could be targeted for phylogenetic markers. This study will contribute to improved resolution of deep branches of the Ilex phylogeny and facilitate identification of Ilex species.

  2. Abscisic acid refines the synthesis of chloroplast proteins in maize (Zea mays) in response to drought and light.

    PubMed

    Hu, Xiuli; Wu, Xiaolin; Li, Chaohai; Lu, Minghui; Liu, Tianxue; Wang, Ying; Wang, Wei

    2012-01-01

    To better understand abscisic acid (ABA) regulation of the synthesis of chloroplast proteins in maize (Zea mays L.) in response to drought and light, we compared leaf proteome differences between maize ABA-deficient mutant vp5 and corresponding wild-type Vp5 green and etiolated seedlings exposed to drought stress. Proteins extracted from the leaves of Vp5 and vp5 seedlings were used for two-dimensional electrophoresis (2-DE) and subsequent matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). After Coomassie brilliant blue staining, approximately 450 protein spots were reproducibly detected on 2-DE gels. A total of 36 differentially expressed protein spots in response to drought and light were identified using MALDI-TOF MS and their subcellular localization was determined based on the annotation of reviewed accession in UniProt Knowledgebase and the software prediction. As a result, corresponding 13 proteins of the 24 differentially expressed protein spots were definitely localized in chloroplasts and their expression was in an ABA-dependent way, including 6 up-regulated by both drought and light, 5 up-regulated by drought but down-regulated by light, 5 up-regulated by light but down-regulated by drought; 5 proteins down-regulated by drought were mainly those involved in photosynthesis and ATP synthesis. Thus, the results in the present study supported the vital role of ABA in regulating the synthesis of drought- and/or light-induced proteins in maize chloroplasts and would facilitate the functional characterization of ABA-induced chloroplast proteins in C(4) plants.

  3. Abscisic Acid Refines the Synthesis of Chloroplast Proteins in Maize (Zea mays) in Response to Drought and Light

    PubMed Central

    Hu, Xiuli; Wu, Xiaolin; Li, Chaohai; Lu, Minghui; Liu, Tianxue; Wang, Ying; Wang, Wei

    2012-01-01

    To better understand abscisic acid (ABA) regulation of the synthesis of chloroplast proteins in maize (Zea mays L.) in response to drought and light, we compared leaf proteome differences between maize ABA-deficient mutant vp5 and corresponding wild-type Vp5 green and etiolated seedlings exposed to drought stress. Proteins extracted from the leaves of Vp5 and vp5 seedlings were used for two-dimensional electrophoresis (2-DE) and subsequent matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). After Coomassie brilliant blue staining, approximately 450 protein spots were reproducibly detected on 2-DE gels. A total of 36 differentially expressed protein spots in response to drought and light were identified using MALDI-TOF MS and their subcellular localization was determined based on the annotation of reviewed accession in UniProt Knowledgebase and the software prediction. As a result, corresponding 13 proteins of the 24 differentially expressed protein spots were definitely localized in chloroplasts and their expression was in an ABA-dependent way, including 6 up-regulated by both drought and light, 5 up-regulated by drought but down-regulated by light, 5 up-regulated by light but down-regulated by drought; 5 proteins down-regulated by drought were mainly those involved in photosynthesis and ATP synthesis. Thus, the results in the present study supported the vital role of ABA in regulating the synthesis of drought- and/or light-induced proteins in maize chloroplasts and would facilitate the functional characterization of ABA-induced chloroplast proteins in C4 plants. PMID:23152915

  4. Functional remodeling of RNA processing in replacement chloroplasts by pathways retained from their predecessors.

    PubMed

    Dorrell, Richard G; Howe, Christopher J

    2012-11-13

    Chloroplasts originate through the endosymbiotic integration of a host and a photosynthetic symbiont, with processes established within the host for the biogenesis and maintenance of the nascent chloroplast. It is thought that several photosynthetic eukaryotes have replaced their original chloroplasts with others derived from different source organisms in a process termed "serial endosymbiosis of chloroplasts." However, it is not known whether replacement chloroplasts are affected by the biogenesis and maintenance pathways established to support their predecessors. Here, we investigate whether pathways established during a previous chloroplast symbiosis function in the replacement chloroplasts of the dinoflagellate alga Karenia mikimotoi. We show that chloroplast transcripts in K. mikimotoi are subject to 3' polyuridylylation and extensive sequence editing. We confirm that these processes do not occur in free-living relatives of the replacement chloroplast lineage, but are otherwise found only in the ancestral, red algal-derived chloroplasts of dinoflagellates and their closest relatives. This indicates that these unusual RNA-processing pathways have been retained from the original symbiont lineage and made use of by the replacement chloroplast. Our results constitute an addition to current theories of chloroplast evolution in which chloroplast biogenesis may be radically remodeled by pathways remaining from previous symbioses.

  5. The rice nuclear gene, VIRESCENT 2, is essential for chloroplast development and encodes a novel type of guanylate kinase targeted to plastids and mitochondria.

    PubMed

    Sugimoto, Hiroki; Kusumi, Kensuke; Noguchi, Ko; Yano, Masahiro; Yoshimura, Atsushi; Iba, Koh

    2007-11-01

    Guanylate kinase (GK) is a critical enzyme in guanine nucleotide metabolism pathways, catalyzing the phosphorylation of (d)GMP to (d)GDP. Here we show that a novel gene, VIRESCENT 2 (V2), encodes a new type of GK (designated pt/mtGK) that is localized in plastids and mitochondria. We initially identified the V2 gene by positional cloning of the rice v2 mutant. The v2 mutant is temperature-sensitive and develops chlorotic leaves at restrictive temperatures. The v2 mutation causes inhibition of chloroplast differentiation; in particular, it disrupts the chloroplast translation machinery during early leaf development [Sugimoto et al. (2004)Plant Cell Physiol. 45, 985]. In the bacterial and animal species studied to date, GK is localized in the cytoplasm and participates in maintenance of the guanine nucleotide pools required for many fundamental cellular processes. Phenotypic analysis of rice seedlings with RNAi knockdown of cytosolic GK (designated cGK) showed that cGK is indispensable for the growth and development of plants, but not for chloroplast development. Thus, rice has two types of GK, as does Arabidopsis, suggesting that higher plants have two types of GK. Our results suggest that, of the two types of GK, only pt/mtGK is essential for chloroplast differentiation.

  6. Computer modeling of electron and proton transport in chloroplasts.

    PubMed

    Tikhonov, Alexander N; Vershubskii, Alexey V

    2014-07-01

    Photosynthesis is one of the most important biological processes in biosphere, which provides production of organic substances from atmospheric CO2 and water at expense of solar energy. In this review, we contemplate computer models of oxygenic photosynthesis in the context of feedback regulation of photosynthetic electron transport in chloroplasts, the energy-transducing organelles of the plant cell. We start with a brief overview of electron and proton transport processes in chloroplasts coupled to ATP synthesis and consider basic regulatory mechanisms of oxygenic photosynthesis. General approaches to computer simulation of photosynthetic processes are considered, including the random walk models of plastoquinone diffusion in thylakoid membranes and deterministic approach to modeling electron transport in chloroplasts based on the mass action law. Then we focus on a kinetic model of oxygenic photosynthesis that includes key stages of the linear electron transport, alternative pathways of electron transfer around photosystem I (PSI), transmembrane proton transport and ATP synthesis in chloroplasts. This model includes different regulatory processes: pH-dependent control of the intersystem electron transport, down-regulation of photosystem II (PSII) activity (non-photochemical quenching), the light-induced activation of the Bassham-Benson-Calvin (BBC) cycle. The model correctly describes pH-dependent feedback control of electron transport in chloroplasts and adequately reproduces a variety of experimental data on induction events observed under different experimental conditions in intact chloroplasts (variations of CO2 and O2 concentrations in atmosphere), including a complex kinetics of P700 (primary electron donor in PSI) photooxidation, CO2 consumption in the BBC cycle, and photorespiration. Finally, we describe diffusion-controlled photosynthetic processes in chloroplasts within the framework of the model that takes into account complex architecture of

  7. Red light, Phot1 and JAC1 modulate Phot2-dependent reorganization of chloroplast actin filaments and chloroplast avoidance movement.

    PubMed

    Ichikawa, Satoshi; Yamada, Noboru; Suetsugu, Noriyuki; Wada, Masamitsu; Kadota, Akeo

    2011-08-01

    The phototropin (phot)-dependent intracellular relocation of chloroplasts is a ubiquitous phenomenon in plants. We have previously revealed the involvement of a short cp-actin (chloroplast actin) filament-based mechanism in this movement. Here, the reorganization of cp-actin filaments during the avoidance movement of chloroplasts was analyzed in higher time resolution under blue GFP (green fluorescent protein) excitation light in an actin filament-visualized line of Arabidopsis thaliana. Under standard background red light of 89 μmol m(-2) s(-1), cp-actin filaments transiently disappeared at approximately 30 s and reappeared in a biased configuration on chloroplasts approximately 70 s after blue excitation light irradiation. The timing of biased cp-actin reappearance was delayed under the background of strong red light or in the absence of red light. Consistently, chloroplast movement was delayed under these conditions. In phot1 mutants, acceleration of both the disappearance and reappearance of cp-actin filaments occurred, indicating an inhibitory action of phot1 on reorganization of cp-actin filaments. Avoidance movements began sooner in phot1 than in wild-type plants. No reorganization of cp-actin filaments was seen in phot2 or phot1phot2 mutants lacking phot2, which is responsible for avoidance movements. Surprisingly, jac1 (j-domain protein required for chloroplast accumulation response 1) mutants, lacking the accumulation response, showed no avoidance movements under the whole-cell irradiation condition for GFP observation. Cp-actin filaments in jac1 did not show a biased distribution, with a small or almost no transient decrease in the number. These results indicate a close association between the biased distribution of cp-actin filaments and chloroplast movement. Further, JAC1 is suggested to function in the biased cp-actin filament distribution by regulating their appearance and disappearance.

  8. Chloroplasts as a nitric oxide cellular source. Effect of reactive nitrogen species on chloroplastic lipids and proteins.

    PubMed

    Jasid, Sebastián; Simontacchi, Marcela; Bartoli, Carlos G; Puntarulo, Susana

    2006-11-01

    Nitric oxide (NO) generation by soybean (Glycine max var. ADM 4800) chloroplasts was studied as an endogenous product assessed by the electron paramagnetic resonance spin-trapping technique. Nitrite and l-arginine (Arg) are substrates for enzymatic activities considered to be the possible sources of NO in plants. Soybean chloroplasts showed a NO production of 3.2 +/- 0.2 nmol min(-1) mg(-1) protein in the presence of 1 mm NaNO(2). Inhibition of photosynthetic electron flow by 3-(3,4-dichlorophenyl)-1,1-dimethyl urea resulted in a lower rate (1.21 +/- 0.04 nmol min(-1) mg(-1) protein) of NO generation. Chloroplasts incubated with 1 mm Arg showed NO production of 0.76 +/- 0.04 nmol min(-1) mg(-1) protein that was not affected either by omission of Ca(2+) or by supplementation with Ca(2+) and calmodulin to the incubation medium. This production was inhibited when chloroplasts were incubated in the presence of NO synthase inhibitors N(omega)-nitro-l-Arg methyl ester hydrochloride and N(omega)-nitro-l-Arg. In vitro exposure of chloroplasts to an NO donor (250 mum S-nitrosoglutathione) decreased lipid radical content in membranes by 29%; however, incubation in the presence of 25 mum peroxynitrite (ONOO(-)) led to an increase in lipid-derived radicals (34%). The effect of ONOO(-) on protein oxidation was determined by western blotting, showing an increase in carbonyl content either in stroma or thylakoid proteins as compared to controls. Moreover, ONOO(-) treatment significantly affected both O(2) evolution and chlorophyll fluorescence in thylakoids. Data reported here suggest that NO is an endogenous metabolite in soybean chloroplasts and that reactive nitrogen species could exert either antioxidant or prooxidant effects on chloroplast macromolecules.

  9. Young Seedling Stripe1 encodes a chloroplast nucleoid-associated protein required for chloroplast development in rice seedlings.

    PubMed

    Zhou, Kunneng; Ren, Yulong; Zhou, Feng; Wang, Ying; Zhang, Long; Lyu, Jia; Wang, Yihua; Zhao, Shaolu; Ma, Weiwei; Zhang, Huan; Wang, Liwei; Wang, Chunming; Wu, Fuqing; Zhang, Xin; Guo, Xiupin; Cheng, Zhijun; Wang, Jiulin; Lei, Cailin; Jiang, Ling; Li, Zefu; Wan, Jianmin

    2017-01-01

    Young Seedling Stripe1 (YSS1) was characterized as an important regulator of plastid-encoded plastid RNA polymerase (PEP) activity essential for chloroplast development at rice seedling stage. Chloroplast development is coordinately regulated by plastid- and nuclear-encoding genes. Although a few regulators have been reported to be involved in chloroplast development, new factors remain to be identified, given the complexity of this process. Here, we report the characterization of a temperature-sensitive young seedling stripe1 (yss1) rice mutant, which develops striated leaves at the seedling stage, particularly in leaf 3, but produces wild-type leaves in leaf 5 and onwards. The chlorotic leaves have decreased chlorophyll (Chls) accumulation and impaired chloroplast structure. Positional cloning combined with sequencing demonstrated that aberrant splicing of the 8th intron in YSS1 gene, due to a single nucleotide deletion around splicing donor site, leads to decreased expression of YSS1 and accumulation of an 8th intron-retained yss1 transcript. Furthermore, complementation test revealed that downregulation of YSS1 but not accumulation of yss1 transcript confers yss1 mutant phenotype. YSS1 encodes a chloroplast nucleoid-localized protein belonging to the DUF3727 superfamily. Expression analysis showed that YSS1 gene is more expressed in newly expanded leaves, and distinctly up-regulated as temperatures increase and by light stimulus. PEP- and nuclear-encoded phage-type RNA polymerase (NEP)-dependent genes are separately down-regulated and up-regulated in yss1 mutant, indicating that PEP activity may be impaired. Furthermore, levels of chloroplast proteins are mostly reduced in yss1 seedlings. Together, our findings identify YSS1 as a novel regulator of PEP activity essential for chloroplast development at rice seedling stage.

  10. Arabidopsis chloroplast chaperonin 10 is a calmodulin-binding protein

    NASA Technical Reports Server (NTRS)

    Yang, T.; Poovaiah, B. W.

    2000-01-01

    Calcium regulates diverse cellular activities in plants through the action of calmodulin (CaM). By using (35)S-labeled CaM to screen an Arabidopsis seedling cDNA expression library, a cDNA designated as AtCh-CPN10 (Arabidopsis thaliana chloroplast chaperonin 10) was cloned. Chloroplast CPN10, a nuclear-encoded protein, is a functional homolog of E. coli GroES. It is believed that CPN60 and CPN10 are involved in the assembly of Rubisco, a key enzyme involved in the photosynthetic pathway. Northern analysis revealed that AtCh-CPN10 is highly expressed in green tissues. The recombinant AtCh-CPN10 binds to CaM in a calcium-dependent manner. Deletion mutants revealed that there is only one CaM-binding site in the last 31 amino acids of the AtCh-CPN10 at the C-terminal end. The CaM-binding region in AtCh-CPN10 has higher homology to other chloroplast CPN10s in comparison to GroES and mitochondrial CPN10s, suggesting that CaM may only bind to chloroplast CPN10s. Furthermore, the results also suggest that the calcium/CaM messenger system is involved in regulating Rubisco assembly in the chloroplast, thereby influencing photosynthesis. Copyright 2000 Academic Press.

  11. Comparison of intraspecific, interspecific and intergeneric chloroplast diversity in Cycads.

    PubMed

    Jiang, Guo-Feng; Hinsinger, Damien Daniel; Strijk, Joeri Sergej

    2016-08-25

    Cycads are among the most threatened plant species. Increasing the availability of genomic information by adding whole chloroplast data is a fundamental step in supporting phylogenetic studies and conservation efforts. Here, we assemble a dataset encompassing three taxonomic levels in cycads, including ten genera, three species in the genus Cycas and two individuals of C. debaoensis. Repeated sequences, SSRs and variations of the chloroplast were analyzed at the intraspecific, interspecific and intergeneric scale, and using our sequence data, we reconstruct a phylogenomic tree for cycads. The chloroplast was 162,094 bp in length, with 133 genes annotated, including 87 protein-coding, 37 tRNA and 8 rRNA genes. We found 7 repeated sequences and 39 SSRs. Seven loci showed promising levels of variations for application in DNA-barcoding. The chloroplast phylogeny confirmed the division of Cycadales in two suborders, each of them being monophyletic, revealing a contradiction with the current family circumscription and its evolution. Finally, 10 intraspecific SNPs were found. Our results showed that despite the extremely restricted distribution range of C. debaoensis, using complete chloroplast data is useful not only in intraspecific studies, but also to improve our understanding of cycad evolution and in defining conservation strategies for this emblematic group.

  12. The complete chloroplast genome of Capsicum frutescens (Solanaceae)1

    PubMed Central

    Shim, Donghwan; Raveendar, Sebastin; Lee, Jung-Ro; Lee, Gi-An; Ro, Na-Young; Jeon, Young-Ah; Cho, Gyu-Taek; Lee, Ho-Sun; Ma, Kyung-Ho; Chung, Jong-Wook

    2016-01-01

    Premise of the study: We report the complete sequence of the chloroplast genome of Capsicum frutescens (Solanaceae), a species of chili pepper. Methods and Results: Using an Illumina platform, we sequenced the chloroplast genome of C. frutescens. The total length of the genome is 156,817 bp, and the overall GC content is 37.7%. A pair of 25,792-bp inverted repeats is separated by small (17,853 bp) and large (87,380 bp) single-copy regions. The C. frutescens chloroplast genome encodes 132 unique genes, including 87 protein-coding genes, 37 transfer RNA (tRNA) genes, and eight ribosomal RNA (rRNA) genes. Of these, seven genes are duplicated in the inverted repeats and 12 genes contain one or two introns. Comparative analysis with the reference chloroplast genome revealed 125 simple sequence repeat motifs and 34 variants, mostly located in the noncoding regions. Conclusions: The complete chloroplast genome sequence of C. frutescens reported here is a valuable genetic resource for Capsicum species. PMID:27213127

  13. Comparison of intraspecific, interspecific and intergeneric chloroplast diversity in Cycads

    PubMed Central

    Jiang, Guo-Feng; Hinsinger, Damien Daniel; Strijk, Joeri Sergej

    2016-01-01

    Cycads are among the most threatened plant species. Increasing the availability of genomic information by adding whole chloroplast data is a fundamental step in supporting phylogenetic studies and conservation efforts. Here, we assemble a dataset encompassing three taxonomic levels in cycads, including ten genera, three species in the genus Cycas and two individuals of C. debaoensis. Repeated sequences, SSRs and variations of the chloroplast were analyzed at the intraspecific, interspecific and intergeneric scale, and using our sequence data, we reconstruct a phylogenomic tree for cycads. The chloroplast was 162,094 bp in length, with 133 genes annotated, including 87 protein-coding, 37 tRNA and 8 rRNA genes. We found 7 repeated sequences and 39 SSRs. Seven loci showed promising levels of variations for application in DNA-barcoding. The chloroplast phylogeny confirmed the division of Cycadales in two suborders, each of them being monophyletic, revealing a contradiction with the current family circumscription and its evolution. Finally, 10 intraspecific SNPs were found. Our results showed that despite the extremely restricted distribution range of C. debaoensis, using complete chloroplast data is useful not only in intraspecific studies, but also to improve our understanding of cycad evolution and in defining conservation strategies for this emblematic group. PMID:27558458

  14. Temperature-dependent signal transmission in chloroplast accumulation response.

    PubMed

    Higa, Takeshi; Hasegawa, Satoshi; Hayasaki, Yoshio; Kodama, Yutaka; Wada, Masamitsu

    2017-07-01

    Chloroplast photorelocation movement, well-characterized light-induced response found in various plant species from alga to higher plants, is an important phenomenon for plants to increase photosynthesis efficiency and avoid photodamage. The signal for chloroplast accumulation movement connecting the blue light receptor, phototropin, and chloroplasts remains to be identified, although the photoreceptors and the mechanism of movement via chloroplast actin filaments have now been revealed in land plants. The characteristics of the signal have been found; the speed of signal transfer is about 1 µm min(-1) and that the signal for the accumulation response has a longer life and is transferred a longer distance than that of the avoidance response. Here, to collect the clues of the unknown signal substances, we studied the effect of temperature on the speed of signal transmission using the fern Adiantum capillus-veneris and found the possibility that the mechanism of signal transfer was not dependent on the simple diffusion of a substance; thus, some chemical reaction must also be involved. We also found new insights of signaling substances, such that microtubules are not involved in the signal transmission, and that the signal could even be transmitted through the narrow space between chloroplasts and the plasma membrane.

  15. The chloroplast view of the evolution of polyploid wheat.

    PubMed

    Gornicki, Piotr; Zhu, Huilan; Wang, Junwei; Challa, Ghana S; Zhang, Zhengzhi; Gill, Bikram S; Li, Wanlong

    2014-11-01

    Polyploid wheats comprise four species: Triticum turgidum (AABB genomes) and T. aestivum (AABBDD) in the Emmer lineage, and T. timopheevii (AAGG) and T. zhukovskyi (AAGGA(m) A(m) ) in the Timopheevi lineage. Genetic relationships between chloroplast genomes were studied to trace the evolutionary history of the species. Twenty-five chloroplast genomes were sequenced, and 1127 plant accessions were genotyped, representing 13 Triticum and Aegilops species. The A. speltoides (SS genome) diverged before the divergence of T. urartu (AA), A. tauschii (DD) and the Aegilops species of the Sitopsis section. Aegilops speltoides forms a monophyletic clade with the polyploid Emmer and Timopheevi wheats, which originated within the last 0.7 and 0.4 Myr, respectively. The geographic distribution of chloroplast haplotypes of the wild tetraploid wheats and A. speltoides illustrates the possible geographic origin of the Emmer lineage in the southern Levant and the Timopheevi lineage in northern Iraq. Aegilops speltoides is the closest relative of the diploid donor of the chloroplast (cytoplasm), as well as the B and G genomes to Timopheevi and Emmer lineages. Chloroplast haplotypes were often shared by species or subspecies within major lineages and between the lineages, indicating the contribution of introgression to the evolution and domestication of polyploid wheats.

  16. Arabidopsis chloroplast chaperonin 10 is a calmodulin-binding protein

    NASA Technical Reports Server (NTRS)

    Yang, T.; Poovaiah, B. W.

    2000-01-01

    Calcium regulates diverse cellular activities in plants through the action of calmodulin (CaM). By using (35)S-labeled CaM to screen an Arabidopsis seedling cDNA expression library, a cDNA designated as AtCh-CPN10 (Arabidopsis thaliana chloroplast chaperonin 10) was cloned. Chloroplast CPN10, a nuclear-encoded protein, is a functional homolog of E. coli GroES. It is believed that CPN60 and CPN10 are involved in the assembly of Rubisco, a key enzyme involved in the photosynthetic pathway. Northern analysis revealed that AtCh-CPN10 is highly expressed in green tissues. The recombinant AtCh-CPN10 binds to CaM in a calcium-dependent manner. Deletion mutants revealed that there is only one CaM-binding site in the last 31 amino acids of the AtCh-CPN10 at the C-terminal end. The CaM-binding region in AtCh-CPN10 has higher homology to other chloroplast CPN10s in comparison to GroES and mitochondrial CPN10s, suggesting that CaM may only bind to chloroplast CPN10s. Furthermore, the results also suggest that the calcium/CaM messenger system is involved in regulating Rubisco assembly in the chloroplast, thereby influencing photosynthesis. Copyright 2000 Academic Press.

  17. Inhibition of chloroplastic respiration by osmotic dehydration. [Spinacia oleracea L

    SciTech Connect

    Willeford, K.O.; Ahluwalia, K.J.K.; Gibbs, M. )

    1989-04-01

    The respiratory capacity of isolated spinach (Spinacia oleracea L.) chloroplasts, measured as the rate of {sup 14}CO{sub 2} evolved from the oxidative pentose phosphate cycle in darkened chloroplasts exogenously supplied with ({sup 14}C)glucose, was progressively diminished by escalating osmotic dehydration with betaine or sorbitol. Comparing the inhibitions of CO{sub 2} evolution generated by osmotic dehydration in chloroplasts given C-1 and C-6 labeled glucose, 54% and 84%, respectively, indicates that osmotic dehydration effects to a greater extent the recycling of the oxidative pentose phosphate intermediates, fructose-6P and glyceraldehyde-3P. Respiratory inhibition in the darkened chloroplast could be alleviated by addition of NH{sub 4}Cl (a stromal alkylating agent), iodoacetamide (an inhibitor of glyceraldehyde-3P dehydrogenase), or glycolate-2P (an inhibitor of phosphofructokinase). It is concluded that the site which primarily mediates respiratory inhibition in the darkened chloroplast occurs at the fructose 1,6-bisphosphatase/phosphofructokinase junction.

  18. Characterization of polymorphic chloroplast microsatellites in Prunus species and maternal lineages in peach genotypes

    USDA-ARS?s Scientific Manuscript database

    Several available Prunus chloroplast genomes have not been exploited to develop polymorphic chloroplast microsatellites that could be useful in Prunus maternal lineage and phylogenetic analysis. In this study, using available bioinformatics tools, 80, 75, and 78 microsatellites were identified from ...

  19. Expression of Brassica oleracea FtsZ1-1 and MinD alters chloroplast division in Nicotiana tabacum generating macro- and mini-chloroplasts.

    PubMed

    Chikkala, Veera R N; Nugent, Gregory D; Stalker, David M; Mouradov, Aidyn; Stevenson, Trevor W

    2012-05-01

    FtsZ1-1 and MinD plastid division-related genes were identified and cloned from Brassica oleracea var. botrytis. Transgenic tobacco plants expressing BoFtsZ1-1 or BoMinD exhibited cells with either fewer but abnormally large chloroplasts or more but smaller chloroplasts relative to wild-type tobacco plants. An abnormal chloroplast phenotype in guard cells was found in BoMinD transgenic tobacco plants but not in BoFtsZ1-1 transgenic tobacco plants. Transgenic tobacco plants bearing the macro-chloroplast phenotype had 10 to 20-fold increased levels of total FtsZ1-1 or MinD, whilst the transgenic tobacco plants bearing the mini-chloroplast phenotype had lower increased FtsZ1-1 or absence of detectable MinD. We also described for the first time, plastid transformation of macro-chloroplast bearing tobacco shoots with a gene cassette allowing for expression of green fluorescent protein (GFP). Homoplasmic plastid transformants from normal chloroplast and macro-chloroplast tobacco plants expressing GFP were obtained. Both types of transformants accumulated GFP at ~6% of total soluble protein, thus indicating that cells containing macro-chloroplasts can regenerate shoots in tissue culture and can stably integrate and express a foreign gene to similar levels as plant cells containing a normal chloroplast size and number.

  20. Oryza sativa Chloroplast Signal Recognition Particle 43 (OscpSRP43) Is Required for Chloroplast Development and Photosynthesis

    PubMed Central

    Xu, Xia; Wei, Yan-lin; Wang, Hui-mei; Zhang, Xiao-bo; Wu, Jian-li

    2015-01-01

    A rice chlorophyll-deficient mutant w67 was isolated from an ethyl methane sulfonate (EMS)–induced IR64 (Oryza sativa L. ssp. indica) mutant bank. The mutant exhibited a distinct yellow-green leaf phenotype in the whole plant growth duration with significantly reduced levels of chlorophyll and carotenoid, impaired chloroplast development and lowered capacity of photosynthesis compared with the wild-type IR64. Expression of a number of genes associated with chlorophyll metabolism, chloroplast biogenesis and photosynthesis was significantly altered in the mutant. Genetic analysis indicated that the yellow-green phenotype was controlled by a single recessive nuclear gene located on the short arm of chromosome 3. Using map-based strategy, the mutation was isolated and predicted to encode a chloroplast signal recognition particle 43 KD protein (cpSRP43) with 388 amino acid residuals. A single base substitution from A to T at position 160 resulted in a premature stop codon. OscpSRP43 was constitutively expressed in various organs with the highest level in the leaf. Functional complementation could rescue the mutant phenotype and subcellular localization showed that the cpSRP43:GFP fusion protein was targeted to the chloroplast. The data suggested that Oryza sativa cpSRP43 (OscpSRP43) was required for the normal development of chloroplasts and photosynthesis in rice. PMID:26600124

  1. Oryza sativa Chloroplast Signal Recognition Particle 43 (OscpSRP43) Is Required for Chloroplast Development and Photosynthesis.

    PubMed

    Lv, Xiang-guang; Shi, Yong-feng; Xu, Xia; Wei, Yan-lin; Wang, Hui-mei; Zhang, Xiao-bo; Wu, Jian-li

    2015-01-01

    A rice chlorophyll-deficient mutant w67 was isolated from an ethyl methane sulfonate (EMS)-induced IR64 (Oryza sativa L. ssp. indica) mutant bank. The mutant exhibited a distinct yellow-green leaf phenotype in the whole plant growth duration with significantly reduced levels of chlorophyll and carotenoid, impaired chloroplast development and lowered capacity of photosynthesis compared with the wild-type IR64. Expression of a number of genes associated with chlorophyll metabolism, chloroplast biogenesis and photosynthesis was significantly altered in the mutant. Genetic analysis indicated that the yellow-green phenotype was controlled by a single recessive nuclear gene located on the short arm of chromosome 3. Using map-based strategy, the mutation was isolated and predicted to encode a chloroplast signal recognition particle 43 KD protein (cpSRP43) with 388 amino acid residuals. A single base substitution from A to T at position 160 resulted in a premature stop codon. OscpSRP43 was constitutively expressed in various organs with the highest level in the leaf. Functional complementation could rescue the mutant phenotype and subcellular localization showed that the cpSRP43:GFP fusion protein was targeted to the chloroplast. The data suggested that Oryza sativa cpSRP43 (OscpSRP43) was required for the normal development of chloroplasts and photosynthesis in rice.

  2. IM30 triggers membrane fusion in cyanobacteria and chloroplasts.

    PubMed

    Hennig, Raoul; Heidrich, Jennifer; Saur, Michael; Schmüser, Lars; Roeters, Steven J; Hellmann, Nadja; Woutersen, Sander; Bonn, Mischa; Weidner, Tobias; Markl, Jürgen; Schneider, Dirk

    2015-05-08

    The thylakoid membrane of chloroplasts and cyanobacteria is a unique internal membrane system harbouring the complexes of the photosynthetic electron transfer chain. Despite their apparent importance, little is known about the biogenesis and maintenance of thylakoid membranes. Although membrane fusion events are essential for the formation of thylakoid membranes, proteins involved in membrane fusion have yet to be identified in photosynthetic cells or organelles. Here we show that IM30, a conserved chloroplast and cyanobacterial protein of approximately 30 kDa binds as an oligomeric ring in a well-defined geometry specifically to membranes containing anionic lipids. Triggered by Mg(2+), membrane binding causes destabilization and eventually results in membrane fusion. We propose that IM30 establishes contacts between internal membrane sites and promotes fusion to enable regulated exchange of proteins and/or lipids in cyanobacteria and chloroplasts.

  3. The complete chloroplast genome sequence of Alocasia macrorrhizos.

    PubMed

    Wang, Bin; Han, Limin

    2016-09-01

    The complete chloroplast sequence of Alocasia macrorrhizos is 154 995 bp in length, containing a pair of inverted repeats of 25 944 bp separated by a large single-copy (LSC) region and a small single-copy (SSC) region of 87 366 bp and 15 741 bp, respectively. The chloroplast genome encodes 132 predicted functional genes, including 87 protein-coding genes, four ribosomal RNA genes, and 37 transfer RNA genes, 18 of which are duplicated in the inverted repeat regions. In these genes, 16 genes contained single intron and two genes comprising double introns. A maximum-likelihood phylogenetic analysis using complete chloroplast genome revealed that A. macrorrhizos does not belong to Araceae family, which infers that the A. macrorrhizos is distant from the species in Araceae family.

  4. Purification and Characterization of Pea Chloroplastic Phosphoriboisomerase 12

    PubMed Central

    Skrukrud, Cynthia L.; Gordon, Ilana M.; Dorwin, Sally; Yuan, Xiao-Hua; Johansson, Göte; Anderson, Louise E.

    1991-01-01

    Pea (Pisum sativum L.) chloroplastic phosphoriboisomerase (EC 5.3.1.6) can be purified to apparent homogeneity in less than 2 days time with a 53% yield. Important steps in the purification include heat treatment and pseudoaffinity chromatography on Red H-3BN Sepharose. The purified isomerase has a subunit molecular mass of 26.4 kD. The N-terminal sequence has been determined through 34 residues. pH optima are 7.8 (ribose-5-phosphate) and 7.7 (ribulose-5-phosphate); Km values are 0.9 millimolar (ribose-5-phosphate) and 0.6 millimolar (ribulose-5-phosphate). The enzyme is inhibited by erythrose-4-phosphate, sedoheptulosebisphosphate, glyceraldehyde-3-phosphate, and 3-phosphoglycerate at concentrations close to those found in photosynthesizing chloroplasts. Countercurrent phase partitioning experiments indicate that the pea chloroplastic phosphoriboisomerase interacts physically with phosphoribulokinase. ImagesFigure 1 PMID:16668459

  5. RNA polyadenylation and decay in mitochondria and chloroplasts.

    PubMed

    Schuster, Gadi; Stern, David

    2009-01-01

    Mitochondria and chloroplasts were originally acquired by eukaryotic cells through endosymbiotic events and retain their own gene expression machinery. One hallmark of gene regulation in these two organelles is the predominance of posttranscriptional control, which is exerted both at the gene-specific and global levels. This review focuses on their mechanisms of RNA degradation, and therefore mainly on the polyadenylation-stimulated degradation pathway. Overall, mitochondria and chloroplasts have retained the prokaryotic RNA decay system, despite evolution in the number and character of the enzymes involved. However, several significant differences exist, of which the presence of stable poly(A) tails, and the location of PNPase in the intermembrane space in animal mitochondria, are perhaps the most remarkable. The known and predicted proteins taking part in polyadenylation-stimulated degradation pathways are described, both in chloroplasts and four mitochondrial types: plant, yeast, trypanosome, and animal.

  6. Shredding the signal: targeting peptide degradation in mitochondria and chloroplasts.

    PubMed

    Kmiec, Beata; Teixeira, Pedro F; Glaser, Elzbieta

    2014-12-01

    The biogenesis and functionality of mitochondria and chloroplasts depend on the constant turnover of their proteins. The majority of mitochondrial and chloroplastic proteins are imported as precursors via their N-terminal targeting peptides. After import, the targeting peptides are cleaved off and degraded. Recent work has elucidated a pathway involved in the degradation of targeting peptides in mitochondria and chloroplasts, with two proteolytic components: the presequence protease (PreP) and the organellar oligopeptidase (OOP). PreP and OOP are specialized in degrading peptides of different lengths, with the substrate restriction being dictated by the structure of their proteolytic cavities. The importance of the intraorganellar peptide degradation is highlighted by the fact that elimination of both oligopeptidases affects growth and development of Arabidopsis thaliana. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Post-Transcriptional Control of Chloroplast Gene Expression

    PubMed Central

    del Campo, Eva M.

    2009-01-01

    Chloroplasts contain their own genome, organized as operons, which are generally transcribed as polycistronic transcriptional units. These primary transcripts are processed into smaller RNAs, which are further modified to produce functional RNAs. The RNA processing mechanisms remain largely unknown and represent an important step in the control of chloroplast gene expression. Such mechanisms include RNA cleavage of pre-existing RNAs, RNA stabilization, intron splicing, and RNA editing. Recently, several nuclear-encoded proteins that participate in diverse plastid RNA processing events have been characterised. Many of them seem to belong to the pentatricopeptide repeat (PPR) protein family that is implicated in many crucial functions including organelle biogenesis and plant development. This review will provide an overview of current knowledge of the post-transcriptional processing in chloroplasts. PMID:19838333

  8. Light affects the structure of Chlamydomonas chloroplast chromosomes.

    PubMed

    Thompson, R J; Mosig, G

    1990-05-11

    We have analyzed changes in the structure of chloroplast chromosomes in response to light in growing Chlamydomonas cells using a crosslinking assay based on the intercalation of HMT (4'-hydroxymethyl-4,5',8-trimethylpsoralen) into DNA. Our results show that the structure of chloroplast chromosomes in at least three widely separated regions is different in light-grown vs. dark-grown cells. Structural changes in chloroplast chromosomes occur within 3 hrs after exposure to light or darkness, respectively. The response to light is not inhibited by atrazine and can be elicited by dim blue light incapable of evolving O2, indicating that it does not require photosynthesis. Inhibition of cytoplasmic protein synthesis with cycloheximide prevents this response to light, indicating that it depends, at least in part, on proteins imported from the cytoplasm.

  9. Breakthrough in chloroplast genetic engineering of agronomically important crops

    PubMed Central

    Daniell, Henry; Kumar, Shashi; Dufourmantel, Nathalie

    2012-01-01

    Chloroplast genetic engineering offers several unique advantages, including high-level transgene expression, multi-gene engineering in a single transformation event and transgene containment by maternal inheritance, as well as a lack of gene silencing, position and pleiotropic effects and undesirable foreign DNA. More than 40 transgenes have been stably integrated and expressed using the tobacco chloroplast genome to confer desired agronomic traits or express high levels of vaccine antigens and biopharmaceuticals. Despite such significant progress, this technology has not been extended to major crops. However, highly efficient soybean, carrot and cotton plastid transformation has recently been accomplished through somatic embryogenesis using species-specific chloroplast vectors. This review focuses on recent exciting developments in this field and offers directions for further research and development. PMID:15866001

  10. A novel light-regulated promoter is conserved in cereal and dicot chloroplasts.

    PubMed Central

    Christopher, D A; Kim, M; Mullet, J E

    1992-01-01

    The chloroplast psbD-psbC genes encode D2 and cp43, a reaction center protein and chlorophyll-binding antenna protein of photosystem II, respectively. We have previously shown that differential accumulation of light-induced psbD-psbC mRNAs in barley chloroplasts is due to transcription from a blue light-responsive promoter (LRP). It is hypothesized that the light-induced mRNAs help to maintain levels of the D2 polypeptide, which is photodamaged and degraded in illuminated plants. To determine if light-induced accumulation of psbD-psbC mRNAs was a conserved phenomenon in chloroplasts, the expression of psbD-psbC operons from five cereals (barley, wheat, rice, maize, and sorghum) and three dicot (tobacco, spinach, and pea) species was examined. Cereal and dicot psbD-psbC operons differ due to several DNA rearrangements that moved psbK-psbI proximal to psbD-psbC, allowing cotranscription of these genes and production of several unique transcripts in cereals. Despite differences in the structure and expression of the cereal and dicot psbD-psbC operons, the accumulation of light-induced psbD-psbC mRNAs was conserved in all species studied. An unusual feature of the light-induced mRNAs was the occurrence of 5' end microheterogeneity. The multiple 5' termini were mapped to several consecutive nucleotides (8 to 25 bp) within a highly conserved (61%) DNA region that represents the transcription initiation site for the mRNAs in barley and tobacco. The novel LRP differs in sequence from typical plastid promoters that have prokaryotic "-10" and "-35" elements and is centered 570 bp (cereals), 900 bp (tobacco, spinach), or 1100 bp (pea) upstream from the psbD translational start codon. We propose that physiological and gene regulatory demands of the chloroplast act as constraints that preserved the linkage of the LRP with psbD despite DNA inversions involving the psbD upstream region. PMID:1392595

  11. A cytoplasmically inherited mutant controlling early chloroplast development in barley seedlings.

    PubMed

    Prina, A R; Arias, M C; Lainez, V; Landau, A; Maldonado, S

    2003-11-01

    Cytoplasmic line 2 (CL2) has been previously reported as a cytoplasmically inherited chlorophyll-deficient mutant selected from a chloroplast-mutator genotype of barley. It was characterized by a localized effect on the upper part of the first-leaf blade. At emergence the CL2 seedlings-phenotype varied from a grainy light green to an albino color. They gradually greened during the following days, starting from the base of the blade and extending to cover most of its surface when it was fully grown. The present results, from both light microscopy and transmission electron microscopy (TEM), confirmed the previously described positional and time-dependent expression of the CL2 syndrome along the first-leaf blade. During the first days after emergence, light microscopy showed a normally developed chloroplast at the middle part of the CL2 first-leaf blade, meanwhile at the tip only small plastids were observed. TEM showed that the shapes and the internal structure of the small plastids were abnormal, presenting features of proplastids, amyloplasts and/or senescent gerontoplasts. Besides, they lack plastid ribosomes, contrasting with what was observed inside chloroplasts from normal tips, which presented abundant ribosomes. Phenotypic observations and spectrophotometric analysis of seedlings produced by mother plants that had been grown under different temperatures indicated that higher temperatures during seed formation were negatively associated with pigment content in CL2 seedlings. In contrast, higher temperatures during the growth of CL2 seedlings have been associated with increased pigment content. Aqueous solution with kanamycin and streptomycin, which are antibiotics known to interfere with plastid gene translation, were used for imbibition of wild-type and CL2 seeds. Antibiotic treatments differentially reduced the chlorophyll content in the upper part of the first-leaf blade in CL2, but not in wild-type seedlings. These results suggest that in the wild

  12. Isolation and Characterization of Chloroplast DNA from the Duckweed Spirodela oligorrhiza

    PubMed Central

    van Ee, Jan H.; Veld, Willem A. Man In'T; Planta, Rudi J.

    1980-01-01

    Chloroplast DNA of the duckweed Spirodela oligorrhiza, isolated by CsCl gradient centrifugation, was characterized by its buoyant density, guanine + cytosine content, melting behavior, circularity, and contour length. In all these characteristics, chloroplast DNA of S. oligorrhiza is similar to the chloroplast genomes of other higher plants, except that it has a significantly larger size. Images PMID:16661479

  13. Actin-dependence of the chloroplast cold positioning response in the liverwort Marchantia polymorpha L.

    PubMed

    Kimura, Shun; Kodama, Yutaka

    2016-01-01

    The subcellular positioning of chloroplasts can be changed by alterations in the environment such as light and temperature. For example, in leaf mesophyll cells, chloroplasts localize along anticlinal cell walls under high-intensity light, and along periclinal cell walls under low-intensity light. These types of positioning responses are involved in photosynthetic optimization. In light-mediated chloroplast positioning responses, chloroplasts move to the appropriate positions in an actin-dependent manner, although some exceptions also depend on microtubule. Even under low-intensity light, at low temperature (e.g., 5°C), chloroplasts localize along anticlinal cell walls; this phenomenon is termed chloroplast cold positioning. In this study, we analyzed whether chloroplast cold positioning is dependent on actin filaments and/or microtubules in the liverwort Marchantia polymorpha L. When liverwort cells were treated with drugs for the de-polymerization of actin filaments, chloroplast cold positioning was completely inhibited. In contrast, chloroplast cold positioning was not affected by treatment with a drug for the de-polymerization of microtubules. These observations indicate the actin-dependence of chloroplast cold positioning in M. polymorpha. Actin filaments during the chloroplast cold positioning response were visualized by using fluorescent probes based on fluorescent proteins in living liverwort cells, and thus, their behavior during the chloroplast cold positioning response was documented.

  14. Possible association of actin filaments with chloroplasts of spinach mesophyll cells in vivo and in vitro.

    PubMed

    Kumatani, T; Sakurai-Ozato, N; Miyawaki, N; Yokota, E; Shimmen, T; Terashima, I; Takagi, S

    2006-11-01

    In palisade mesophyll cells of spinach (Spinacia oleracea L.) kept under low-intensity white light, chloroplasts were apparently immobile and seemed to be surrounded by fine bundles of actin filaments. High-intensity blue light induced actin-dependent chloroplast movement concomitant with the appearance of a couple of long, straight bundles of actin filaments in each cell, whereas high-intensity red light was essentially ineffective in inducing these responses. The actin organization observed under low-intensity white light has been postulated to function in anchoring chloroplasts at proper intracellular positions through direct interaction with the chloroplasts. Intact chloroplasts, which retained their outer envelopes, were isolated after homogenization of leaves and Percoll centrifugation. No endogenous actin was detected by immunoblotting in the final intact-chloroplast fraction prepared from the leaves kept under low-intensity white light or in darkness. In cosedimentation assays with exogenously added skeletal muscle filamentous actin, however, actin was detected in the intact-chloroplast fraction precipitated after low-speed centrifugation. The association of actin with chloroplasts was apparently dependent on incubation time and chloroplast density. After partial disruption of the outer envelope of isolated chloroplasts by treatment with trypsin, actin was no longer coprecipitated. The results suggest that chloroplasts in spinach leaves can directly interact with actin, and that this interaction may be involved in the regulation of intracellular positioning of chloroplasts.

  15. Appearance of Three Chloroplast Isoenzymes in Dark-grown Pea Plants and Pea Seeds 12

    PubMed Central

    Park, Kyung Eun Yoon; Anderson, Louise E.

    1973-01-01

    Activity peaks characteristic of the chloroplastic Calvin cycle enzymes triose-phosphate isomerase, ribose 5-phosphate isomerase, and fructose 1,6-diphosphate aldolase are found in isoelectric focusing patterns of dark-grown pea (Pisum sativum) seedlings and seeds. Apparently, in this higher plant these three chloroplastic isoenzymes can be formed in the absence of light and of chloroplast formation. PMID:16658311

  16. Effect of Flooding on Starch Accumulation in Chloroplasts of Sunflower (Helianthus annuus L.) 1

    PubMed Central

    Wample, Robert L.; Davis, Ronald W.

    1983-01-01

    Chloroplasts in leaves of sunflower (Helianthus annuus L. cv hybrid 894) whose roots were flooded for 4 days showed an increase in the level of starch in chloroplasts when examined with the electron microscope. Starch determination showed significantly higher levels in leaves of flooded plants. Chloroplast and mitochondrial structure seemed otherwise normal. Images Fig. 1 Fig. 2 PMID:16663176

  17. Manipulating the chloroplast genome of Chlamydomonas: Present realities and future prospects

    SciTech Connect

    Boynton, J.; Gillham, N.; Hauser, C.; Heifetz, P.; Lers, A.; Newman, S.; Osmond, B.

    1992-12-31

    Biotechnology is being applied in vitro modification and stable reintroduction of chloroplast genes in Chlamydomonas reinhardtii and Nicotiana tabacum by homologous recombination. We are attempting the function analyses of plastid encoded proteins involved in photosynthesis, characterization of sequences which regulate expression of plastid genes at the transcriptional and translational levels, targeted disruption of chloroplast genes and molecular analysis of processes involved in chloroplast recombination.

  18. Manipulating the chloroplast genome of Chlamydomonas: Present realities and future prospects

    SciTech Connect

    Boynton, J.; Gillham, N.; Hauser, C.; Heifetz, P.; Lers, A.; Newman, S.; Osmond, B.

    1992-01-01

    Biotechnology is being applied in vitro modification and stable reintroduction of chloroplast genes in Chlamydomonas reinhardtii and Nicotiana tabacum by homologous recombination. We are attempting the function analyses of plastid encoded proteins involved in photosynthesis, characterization of sequences which regulate expression of plastid genes at the transcriptional and translational levels, targeted disruption of chloroplast genes and molecular analysis of processes involved in chloroplast recombination.

  19. Actin-dependence of the chloroplast cold positioning response in the liverwort Marchantia polymorpha L.

    PubMed Central

    Kimura, Shun

    2016-01-01

    The subcellular positioning of chloroplasts can be changed by alterations in the environment such as light and temperature. For example, in leaf mesophyll cells, chloroplasts localize along anticlinal cell walls under high-intensity light, and along periclinal cell walls under low-intensity light. These types of positioning responses are involved in photosynthetic optimization. In light-mediated chloroplast positioning responses, chloroplasts move to the appropriate positions in an actin-dependent manner, although some exceptions also depend on microtubule. Even under low-intensity light, at low temperature (e.g., 5°C), chloroplasts localize along anticlinal cell walls; this phenomenon is termed chloroplast cold positioning. In this study, we analyzed whether chloroplast cold positioning is dependent on actin filaments and/or microtubules in the liverwort Marchantia polymorpha L. When liverwort cells were treated with drugs for the de-polymerization of actin filaments, chloroplast cold positioning was completely inhibited. In contrast, chloroplast cold positioning was not affected by treatment with a drug for the de-polymerization of microtubules. These observations indicate the actin-dependence of chloroplast cold positioning in M. polymorpha. Actin filaments during the chloroplast cold positioning response were visualized by using fluorescent probes based on fluorescent proteins in living liverwort cells, and thus, their behavior during the chloroplast cold positioning response was documented. PMID:27703856

  20. Transcriptome analysis of ectopic chloroplast development in green curd cauliflower (Brassica oleracea L. var. botrytis)

    USDA-ARS?s Scientific Manuscript database

    Chloroplasts are the green plastids where photosynthesis takes place. The biogenesis of chloroplasts requires the coordinate expression of both nuclear and chloroplast genes and is regulated by developmental and environmental signals. Despite extensive studies of this process, the genetic basis and ...

  1. Phosphatidylinositol 4-Phosphate Negatively Regulates Chloroplast Division in Arabidopsis[OPEN

    PubMed Central

    Okazaki, Kumiko; Miyagishima, Shin-ya; Wada, Hajime

    2015-01-01

    Chloroplast division is performed by the constriction of envelope membranes at the division site. Although constriction of a ring-like protein complex has been shown to be involved in chloroplast division, it remains unknown how membrane lipids participate in the process. Here, we show that phosphoinositides with unknown function in envelope membranes are involved in the regulation of chloroplast division in Arabidopsis thaliana. PLASTID DIVISION1 (PDV1) and PDV2 proteins interacted specifically with phosphatidylinositol 4-phosphate (PI4P). Inhibition of phosphatidylinositol 4-kinase (PI4K) decreased the level of PI4P in chloroplasts and accelerated chloroplast division. Knockout of PI4Kβ2 expression or downregulation of PI4Kα1 expression resulted in decreased levels of PI4P in chloroplasts and increased chloroplast numbers. PI4Kα1 is the main contributor to PI4P synthesis in chloroplasts, and the effect of PI4K inhibition was largely abolished in the pdv1 mutant. Overexpression of DYNAMIN-RELATED PROTEIN5B (DRP5B), another component of the chloroplast division machinery, which is recruited to chloroplasts by PDV1 and PDV2, enhanced the effect of PI4K inhibition, whereas overexpression of PDV1 and PDV2 had additive effects. The amount of DRP5B that associated with chloroplasts increased upon PI4K inhibition. These findings suggest that PI4P is a regulator of chloroplast division in a PDV1- and DRP5B-dependent manner. PMID:25736058

  2. Salinity induces membrane structure and lipid changes in maize mesophyll and bundle sheath chloroplasts.

    PubMed

    Omoto, Eiji; Iwasaki, Yugo; Miyake, Hiroshi; Taniguchi, Mitsutaka

    2016-05-01

    The membranes of Zea mays (maize) mesophyll cell (MC) chloroplasts are more vulnerable to salinity stress than are those of bundle sheath cell (BSC) chloroplasts. To clarify the mechanism underlying this difference in salt sensitivity, we monitored changes in the glycerolipid and fatty acid compositions of both types of chloroplast upon exposure to salinity stress. The monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) contents were higher in MC chloroplasts than in BSC chloroplasts, in both the presence and absence of salt treatment. Under salt conditions, the MGDG level in MC chloroplasts was significantly lower than under normal conditions, while it was unchanged in BSC chloroplasts. In both types of chloroplast, the contents of DGDG, phosphatidylglycerol and phosphatidylinositol remained at the same levels in control and salt-treated plants, whereas sulfoquinovosyldiacylglycerol and phosphatidylcholine were significantly lower and higher, respectively, upon salt treatment. In addition, the fatty acid composition and double bond index of individual lipid classes were changed by salt treatment in both BSC and MC chloroplasts, although these factors had no effect on glycerolipid content. These findings suggest that the difference in salt sensitivity of MC and BSC chloroplast membranes is related to differences in MGDG responses to salinity. Thus, we propose that the low MGDG content and the low sensitivity of MGDG to salinity in BSC chloroplasts render them more tolerant than MC chloroplasts to salinity stress. © 2015 Scandinavian Plant Physiology Society.

  3. Localization of phosphatidylcholine in outer envelope membrane of spinach chloroplasts

    PubMed Central

    1985-01-01

    We have examined the effects of phospholipase C from Bacillus cereus on the extent of phospholipid hydrolysis in envelope membrane vesicles and in intact chloroplasts. When isolated envelope vesicles were incubated in presence of phospholipase C, phosphatidylcholine and phosphatidylglycerol, but not phosphatidylinositol, were totally converted into diacylglycerol if they were available to the enzyme (i.e., when the vesicles were sonicated in presence of phospholipase C). These experiments demonstrate that phospholipase C can be used to probe the availability of phosphatidylcholine and phosphatidylglycerol in the cytosolic leaflet of the outer envelope membrane from spinach chloroplasts. When isolated, purified, intact chloroplasts were incubated with low amounts of phospholipase C (0.3 U/mg chlorophyll) under very mild conditions (12 degrees C for 1 min), greater than 80% of phosphatidylcholine molecules and almost none of phosphatidylglycerol molecules were hydrolyzed. Since we have also demonstrated, by using several different methods (phase-contrast and electron microscopy, immunochemical and electrophoretic analyses) that isolated spinach chloroplasts, and especially their outer envelope membrane, remained intact after mild treatment with phospholipase C, we can conclude that there is a marked asymmetric distribution of phospholipids across the outer envelope membrane of spinach chloroplasts. Phosphatidylcholine, the major polar lipid of the outer envelope membrane, is almost entirely accessible from the cytosolic side of the membrane and therefore is probably localized in the outer leaflet of the outer envelope bilayer. On the contrary, phosphatidylglycerol, the major polar lipid in the inner envelope membrane and the thylakoids, is probably not accessible to phospholipase C from the cytosol and therefore is probably localized mostly in the inner leaflet of the outer envelope membrane and in the other chloroplast membranes. PMID:3988805

  4. Localization of reactive oxygen species and change of antioxidant capacities in mesophyll and bundle sheath chloroplasts of maize under salinity.

    PubMed

    Omoto, Eiji; Nagao, Haruto; Taniguchi, Mitsutaka; Miyake, Hiroshi

    2013-09-01

    In maize, the structure of bundle sheath cell (BSC) chloroplasts is less subject to salinity stress than that of mesophyll cell (MC) chloroplasts. To elucidate the difference in sensitivity to salinity, antioxidant capacities and localization of reactive oxygen species were investigated in both chloroplasts. Transmission electron microscopic observation showed that O2 (-) localization was found in both chloroplasts under salinity, but the accumulation was much greater in MC chloroplasts. H2 O2 localization was observed only in MC chloroplasts of salt-treated plants. In isolated chloroplasts, the activities of superoxide dismutase (SOD, EC 1.15.1.1), ascorbate peroxidase (APX, EC 1.11.1.11) and dehydroascorbate reductase (DHAR, EC 1.8.5.1) were increased by salinity. While the enhancement of SOD activity was similar in both chloroplasts, the increase of APX and DHAR activities were more pronounced in BSC chloroplasts than in MC chloroplasts. Monodehydroascorbate reductase (MDHAR, EC 1.6.5.4) and glutathione reductase (GR, EC 1.6.4.2) were undetectable in BSC chloroplasts, while they increased in MC chloroplasts under salinity. Although ascorbate content increased by salinity only in BSC chloroplasts, glutathione content increased significantly in both chloroplasts, and was higher in MC chloroplasts than in BSC chloroplasts. The content of thiobarbituric acid-reactive substances, which is an indicator of lipid peroxidation, was significantly increased by salinity in both chloroplasts. These results suggested O2 (-) -scavenging capacity was comparable between both chloroplasts, whereas H2 O2 -scavenging capacity was lower in MC chloroplasts than in BSC chloroplasts. Moreover, the increased lipid peroxidation under salinity was associated with the structural alteration in MC chloroplasts, while it had less impact on the structure of BSC chloroplasts. © 2012 Scandinavian Plant Physiology Society.

  5. Paternal inheritance of chloroplast DNA in interspecific hybrids in the genus Larrea (Zygophyllaceae).

    PubMed

    Yang, T W; Yang, Y A; Xiong, Z

    2000-10-01

    The mode of chloroplast DNA (cpDNA) inheritance was investigated in the genus Larrea (Zygophyllaceae) by polymerase chain reaction (PCR) amplification of cpDNA fragments using three pairs of chloroplast universal primers. A total of 20 F(1)s from interspecific crosses among five different taxa in the section Bifolium was examined. Twelve F(1)s were from six crosses between L. cuneifolia (4x) and L. divaricata (2x) (Peru or Argentina) or L. tridentata (2x or 4x). Eight F(1)s were from two sets of reciprocal crosses between L. divaricata (2x) (Argentina) and L. tridentata (2x). Length polymorphism was observed in all three regions of cpDNA that separated L. cuneifolia parents from L. divaricata and L. tridentata parents and in one of the three cpDNA regions that differentiated L. divaricata (Argentina) parents from L. tridentata (2x) parents. In each case, it was the paternal cpDNA marker that appeared in the F(1) individuals. This was further confirmed by restriction fragment length polymorphism (RFLP) analysis of the amplified cpDNA fragments. Larrea may be the fifth genus reported in angiosperms with a paternal bias in cpDNA transmission. Possible mechanisms that may result in paternal cpDNA inheritance were briefly reviewed. Based on the observed uniparental paternal inheritance of cpDNA, restriction analysis of the three cpDNA regions and previous cytogenetic studies, L. divaricata was probably the maternal progenitor of L. cuneifolia.

  6. Chloroplast genomes of two conifers lack a large inverted repeat and are extensively rearranged.

    PubMed Central

    Strauss, S H; Palmer, J D; Howe, G T; Doerksen, A H

    1988-01-01

    Chloroplast genomes of Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] and radiata (Monterey) pine [Pinus radiata D. Don], two conifers from the widespread Pinaceae, were mapped and their genomes were compared to other land plants. Douglas-fir and radiata pine lack the large (20-25 kilobases) inverted repeat that characterizes most land plants. To our knowledge, this is only the second recorded loss of this ancient and highly conserved inverted repeat among all lineages of land plants thus far examined. Loss of the repeat largely accounts for the small size of the conifer genome, 120 kilobase, versus 140-160 kilobases in most land plants. Douglas-fir possesses a major inversion of 40-50 kilobases relative to radiata pine and nonconiferous plants. Nucleotide sequence differentiation between Douglas-fir and radiata pine was estimated to be 3.8%. Both conifer genomes possess a number of rearrangements relative to Osmunda, a fern, Ginkgo, a gymnosperm, and Petunia, an angiosperm. Among land plants, structural changes of this degree have occurred primarily within tribes of the legume family (Fabaceae) that have also lost the inverted repeat. These results support the hypothesis that the presence of the large inverted repeat stabilizes the chloroplast genome against major structural rearrangements. PMID:2836862

  7. Melatonin biosynthesis in plants: multiple pathways catalyze tryptophan to melatonin in the cytoplasm or chloroplasts.

    PubMed

    Back, Kyoungwhan; Tan, Dun-Xian; Reiter, Russel J

    2016-11-01

    Melatonin is an animal hormone as well as a signaling molecule in plants. It was first identified in plants in 1995, and almost all enzymes responsible for melatonin biosynthesis had already been characterized in these species. Melatonin biosynthesis from tryptophan requires four-step reactions. However, six genes, that is, TDC, TPH, T5H, SNAT, ASMT, and COMT, have been implicated in the synthesis of melatonin in plants, suggesting the presence of multiple pathways. Two major pathways have been proposed based on the enzyme kinetics: One is the tryptophan/tryptamine/serotonin/N-acetylserotonin/melatonin pathway, which may occur under normal growth conditions; the other is the tryptophan/tryptamine/serotonin/5-methoxytryptamine/melatonin pathway, which may occur when plants produce large amounts of serotonin, for example, upon senescence. The melatonin biosynthetic capacity associated with conversion of tryptophan to serotonin is much higher than that associated with conversion of serotonin to melatonin, which yields a low level of melatonin synthesis in plants. Many melatonin intermediates are produced in various subcellular compartments, such as the cytoplasm, endoplasmic reticulum, and chloroplasts, which either facilitates or impedes the subsequent enzymatic steps. Depending on the pathways, the final subcellular sites of melatonin synthesis vary at either the cytoplasm or chloroplasts, which may differentially affect the mode of action of melatonin in plants.

  8. Chloroplast dysfunction causes multiple defects in cell cycle progression in the Arabidopsis crumpled leaf mutant.

    PubMed

    Hudik, Elodie; Yoshioka, Yasushi; Domenichini, Séverine; Bourge, Mickaël; Soubigout-Taconnat, Ludivine; Mazubert, Christelle; Yi, Dalong; Bujaldon, Sandrine; Hayashi, Hiroyuki; De Veylder, Lieven; Bergounioux, Catherine; Benhamed, Moussa; Raynaud, Cécile

    2014-09-01

    The majority of research on cell cycle regulation is focused on the nuclear events that govern the replication and segregation of the genome between the two daughter cells. However, eukaryotic cells contain several compartmentalized organelles with specialized functions, and coordination among these organelles is required for proper cell cycle progression, as evidenced by the isolation of several mutants in which both organelle function and overall plant development were affected. To investigate how chloroplast dysfunction affects the cell cycle, we analyzed the crumpled leaf (crl) mutant of Arabidopsis (Arabidopsis thaliana), which is deficient for a chloroplastic protein and displays particularly severe developmental defects. In the crl mutant, we reveal that cell cycle regulation is altered drastically and that meristematic cells prematurely enter differentiation, leading to reduced plant stature and early endoreduplication in the leaves. This response is due to the repression of several key cell cycle regulators as well as constitutive activation of stress-response genes, among them the cell cycle inhibitor SIAMESE-RELATED5. One unique feature of the crl mutant is that it produces aplastidic cells in several organs, including the root tip. By investigating the consequence of the absence of plastids on cell cycle progression, we showed that nuclear DNA replication occurs in aplastidic cells in the root tip, which opens future research prospects regarding the dialogue between plastids and the nucleus during cell cycle regulation in higher plants.

  9. Non-reductive modulation of chloroplast fructose-1,6-bisphosphatase by 2-Cys peroxiredoxin

    SciTech Connect

    Caporaletti, Daniel; D'Alessio, Ana C.; Rodriguez-Suarez, Roberto J.; Senn, Alejandro M.; Duek, Paula D.; Wolosiuk, Ricardo A. . E-mail: rwolosiuk@leloir.org.ar

    2007-04-13

    2-Cys peroxiredoxin (2-Cys Prx) is a large group of proteins that participate in cell proliferation, differentiation, apoptosis, and photosynthesis. In the prevailing view, this ubiquitous peroxidase poises the concentration of H{sub 2}O{sub 2} and, in so doing, regulates signal transduction pathways or protects macromolecules against oxidative damage. Here, we describe First purification of 2-Cys Prx from higher plants and subsequently we show that the native and the recombinant forms of rapeseed leaves stimulate the activity of chloroplast fructose-1,6-bisphosphatase (CFBPase), a key enzyme of the photosynthetic CO{sub 2} assimilation. The absence of reductants, the strict requirement of both fructose 1,6-bisphosphate and Ca{sup 2+}, and the response of single mutants C174S and C179S CFBPase bring forward clear differences with the well-known stimulation mediated by reduced thioredoxin via the regulatory 170's loop of CFBPase. Taken together, these findings provide an unprecedented insight into chloroplast enzyme regulation wherein both 2-Cys Prx and the 170's loop of CFBPase exhibit novel functions.

  10. Multiple feedbacks between chloroplast and whole plant in the context of plant adaptation and acclimation to the environment

    PubMed Central

    Demmig-Adams, Barbara; Stewart, Jared J.; Adams, William W.

    2014-01-01

    This review focuses on feedback pathways that serve to match plant energy acquisition with plant energy utilization, and thereby aid in the optimization of chloroplast and whole-plant function in a given environment. First, the role of source–sink signalling in adjusting photosynthetic capacity (light harvesting, photochemistry and carbon fixation) to meet whole-plant carbohydrate demand is briefly reviewed. Contrasting overall outcomes, i.e. increased plant growth versus plant growth arrest, are described and related to respective contrasting environments that either do or do not present opportunities for plant growth. Next, new insights into chloroplast-generated oxidative signals, and their modulation by specific components of the chloroplast's photoprotective network, are reviewed with respect to their ability to block foliar phloem-loading complexes, and, thereby, affect both plant growth and plant biotic defences. Lastly, carbon export capacity is described as a newly identified tuning point that has been subjected to the evolution of differential responses in plant varieties (ecotypes) and species from different geographical origins with contrasting environmental challenges. PMID:24591724

  11. Molecular characterization of a positively photoregulated nuclear gene for a chloroplast RNA polymerase sigma factor in Cyanidium caldarium.

    PubMed Central

    Liu, B; Troxler, R F

    1996-01-01

    We have cloned the gene for a putative chloroplast RNA polymerase sigma factor from the unicellular rhodophyte Cyanidium caldarium. This gene contains an open reading frame encoding a protein of 609 amino acids with domains highly homologous to all four conserved regions found in bacterial and cyanobacterial sigma 70-type subunits. When Southern blots of genomic DNA were hybridized to the "rpoD box" oligonucleotide probe, up to six hybridizing hands were observed. Transcripts of the sigma factor gene were undetectable in RNA from dark-grown cells but were abundant in the poly(A)+ fraction of RNA from illuminated cells. The sigma factor gene was expressed in Escherichia coli, and antibodies against the expressed sigma factor fusion protein cross-reacted with a 55-kDa protein in partially purified chloroplast RNA polymerase. Antibodies directed against a cyanobacterial RNA polymerase sigma factor also cross-reacted with a 55-kDa protein in the same enzyme preparation. Immunoprecipitation experiments showed that this enzyme preparation contains proteins with the same molecular weights as the alpha, beta, beta', and beta" subunits of chloroplast RNA polymerase in higher plants. This study identifies a gene for a plastid RNA polymerase sigma factor and indicates that there may be a family of nuclear-encoded sigma factors that recognize promoters in subsets of plastid genes and regulate differential gene expression at the transcriptional level. Images Fig. 1 Fig. 4 Fig. 6 PMID:8622935

  12. Multiple feedbacks between chloroplast and whole plant in the context of plant adaptation and acclimation to the environment.

    PubMed

    Demmig-Adams, Barbara; Stewart, Jared J; Adams, William W

    2014-04-19

    This review focuses on feedback pathways that serve to match plant energy acquisition with plant energy utilization, and thereby aid in the optimization of chloroplast and whole-plant function in a given environment. First, the role of source-sink signalling in adjusting photosynthetic capacity (light harvesting, photochemistry and carbon fixation) to meet whole-plant carbohydrate demand is briefly reviewed. Contrasting overall outcomes, i.e. increased plant growth versus plant growth arrest, are described and related to respective contrasting environments that either do or do not present opportunities for plant growth. Next, new insights into chloroplast-generated oxidative signals, and their modulation by specific components of the chloroplast's photoprotective network, are reviewed with respect to their ability to block foliar phloem-loading complexes, and, thereby, affect both plant growth and plant biotic defences. Lastly, carbon export capacity is described as a newly identified tuning point that has been subjected to the evolution of differential responses in plant varieties (ecotypes) and species from different geographical origins with contrasting environmental challenges.

  13. Systematic analysis of plant mitochondrial and chloroplast small RNAs suggests organelle-specific mRNA stabilization mechanisms.

    PubMed

    Ruwe, Hannes; Wang, Gongwei; Gusewski, Sandra; Schmitz-Linneweber, Christian

    2016-09-06

    Land plant organellar genomes encode a small number of genes, many of which are essential for respiration and photosynthesis. Organellar gene expression is characterized by a multitude of RNA processing events that lead to stable, translatable transcripts. RNA binding proteins (RBPs), have been shown to generate and protect transcript termini and eventually induce the accumulation of short RNA footprints. We applied knowledge of such RBP-derived footprints to develop software (sRNA miner) that enables identification of RBP footprints, or other clusters of small RNAs, in organelles. We used this tool to determine mitochondrial and chloroplast cosRNAs (clustered organellar sRNAs) in Arabidopsis. We found that in mitochondria, cosRNAs coincide with transcript 3'-ends, but are largely absent from 5'-ends. In chloroplasts this bias is absent, suggesting a different mode of 5' processing, possibly owing to different sets of RNases. Furthermore, we identified a large number of cosRNAs that represent silenced insertions of mitochondrial DNA in the nuclear genome of Arabidopsis. Steady-state RNA analyses demonstrate that cosRNAs display differential accumulation during development. Finally, we demonstrate that the chloroplast RBP PPR10 associates in vivo with its cognate cosRNA. A hypothetical role of cosRNAs as competitors of mRNAs for PPR proteins is discussed. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

  14. Phenotypic, histological and proteomic analyses reveal multiple differences associated with chloroplast development in yellow and variegated variants from Camellia sinensis

    PubMed Central

    Ma, Chengying; Cao, Junxi; Li, Jianke; Zhou, Bo; Tang, Jinchi; Miao, Aiqing

    2016-01-01

    Leaf colour variation is observed in several plants. We obtained two types of branches with yellow and variegated leaves from Camellia sinensis. To reveal the mechanisms that underlie the leaf colour variations, combined morphological, histological, ionomic and proteomic analyses were performed using leaves from abnormal branches (variants) and normal branches (CKs). The measurement of the CIE-Lab coordinates showed that the brightness and yellowness of the variants were more intense than the CKs. When chloroplast profiles were analysed, HY1 (branch with yellow leaves) and HY2 (branch with variegated leaves) displayed abnormal chloroplast structures and a reduced number and size compared with the CKs, indicating that the abnormal chloroplast development might be tightly linked to the leaf colour variations. Moreover, the concentration of elemental minerals was different between the variants and the CKs. Furthermore, DEPs (differentially expressed proteins) were identified in the variants and the CKs by a quantitative proteomics analysis using the label-free approach. The DEPs were significantly involved in photosynthesis and included PSI, PSII, cytochrome b6/f complex, photosynthetic electron transport, LHC and F-type ATPase. Our results suggested that a decrease in the abundance of photosynthetic proteins might be associated with the changes of leaf colours in tea plants. PMID:27633059

  15. Changing the light environment: chloroplast signalling and response mechanisms.

    PubMed

    Spetea, Cornelia; Rintamäki, Eevi; Schoefs, Benoît

    2014-04-19

    Light is an essential environmental factor required for photosynthesis, but it also mediates signals to control plant development and growth and induces stress tolerance. The photosynthetic organelle (chloroplast) is a key component in the signalling and response network in plants. This theme issue of Philosophical Transactions of the Royal Society of London B: Biology provides updates, highlights and summaries of the most recent findings on chloroplast-initiated signalling cascades and responses to environmental changes, including light and biotic stress. Besides plant molecular cell biology and physiology, the theme issue includes aspects from the cross-disciplinary fields of environmental adaptation, ecology and agronomy.

  16. Circadian oscillations of cytosolic and chloroplastic free calcium in plants

    NASA Technical Reports Server (NTRS)

    Johnson, C. H.; Knight, M. R.; Kondo, T.; Masson, P.; Sedbrook, J.; Haley, A.; Trewavas, A.

    1995-01-01

    Tobacco and Arabidopsis plants, expressing a transgene for the calcium-sensitive luminescent protein apoaequorin, revealed circadian oscillations in free cytosolic calcium that can be phase-shifted by light-dark signals. When apoaequorin was targeted to the chloroplast, circadian chloroplast calcium rhythms were likewise observed after transfer of the seedlings to constant darkness. Circadian oscillations in free calcium concentrations can be expected to control many calcium-dependent enzymes and processes accounting for circadian outputs. Regulation of calcium flux is therefore fundamental to the organization of circadian systems.

  17. A chloroplast retrograde signal regulates nuclear alternative splicing

    PubMed Central

    Petrillo, Ezequiel; Herz, Micaela A. Godoy; Fuchs, Armin; Reifer, Dominik; Fuller, John; Yanovsky, Marcelo J.; Simpson, Craig; Brown, John W. S.; Barta, Andrea; Kalyna, Maria; Kornblihtt, Alberto R.

    2015-01-01

    Light is a source of energy and also a regulator of plant physiological adaptations. We show here that light/dark conditions affect alternative splicing of a subset of Arabidopsis genes preferentially encoding proteins involved in RNA processing. The effect requires functional chloroplasts and is also observed in roots when the communication with the photosynthetic tissues is not interrupted, suggesting that a signaling molecule travels through the plant. Using photosynthetic electron transfer inhibitors with different mechanisms of action we deduce that the reduced pool of plastoquinones initiates a chloroplast retrograde signaling that regulates nuclear alternative splicing and is necessary for proper plant responses to varying light conditions. PMID:24763593

  18. Robust expression of a bioactive mammalian protein in Chlamydomonas chloroplast

    DOEpatents

    Mayfield, Stephen P

    2015-01-13

    Methods and compositions are disclosed to engineer chloroplast comprising heterologous mammalian genes via a direct replacement of chloroplast Photosystem II (PSII) reaction center protein coding regions to achieve expression of recombinant protein above 5% of total protein. When algae is used, algal expressed protein is produced predominantly as a soluble protein where the functional activity of the peptide is intact. As the host algae is edible, production of biologics in this organism for oral delivery of proteins/peptides, especially gut active proteins, without purification is disclosed.

  19. Robust expression of a bioactive mammalian protein in chlamydomonas chloroplast

    DOEpatents

    Mayfield, Stephen P.

    2010-03-16

    Methods and compositions are disclosed to engineer chloroplast comprising heterologous mammalian genes via a direct replacement of chloroplast Photosystem II (PSII) reaction center protein coding regions to achieve expression of recombinant protein above 5% of total protein. When algae is used, algal expressed protein is produced predominantly as a soluble protein where the functional activity of the peptide is intact. As the host algae is edible, production of biologics in this organism for oral delivery or proteins/peptides, especially gut active proteins, without purification is disclosed.

  20. The complete chloroplast genome sequence of desert poplar (Populus euphratica).

    PubMed

    Zhang, Qun-jie; Gao, Li-zhi

    2016-01-01

    The complete chloroplast sequence of the desert poplar (Populus euphratica), a plant well-adapted to salt stress, was determined in this study. The genome consists of 156,766 bp containing a pair of inverted repeats (IRs) of 16,591 bp separated by a large single-copy region and a small single-copy region of 84,888 bp and 27,646 bp, respectively. The chloroplast genome contains 130 known genes, including 89 protein-coding genes, 8 ribosomal RNA genes, and 37 tRNA genes; 18 of these are located in the inverted repeat region.

  1. FRACTIONATION OF SPINACH CHLOROPLASTS BY FLOW SEDIMENTATION-ELECTROPHORESIS

    PubMed Central

    Packer, Lester; Nobel, Park S.; Gross, Elizabeth L.; Mel, Howard C.

    1966-01-01

    A separation of spinach chloroplasts in vitro into fractions according to size (volume) and activity (light-dependent shrinkage and NADP reduction) has been achieved by stable-flow free boundary sedimentation-electrophoresis. The salient features of this chloroplast study are: (a) separation is achieved within 30 min; (b) only small density gradients are required, thus minimizing osmotic effects; (c) the fractions are collected continuously, with size fractionation being evidenced; and (d) particles are separated into fractions of higher and lower activities as compared with the control population. PMID:5960807

  2. Protein transport in chloroplasts - targeting to the intermembrane space.

    PubMed

    Vojta, Lea; Soll, Jürgen; Bölter, Bettina

    2007-10-01

    The import of proteins destined for the intermembrane space of chloroplasts has not been investigated in detail up to now. By investigating energy requirements and time courses, as well as performing competition experiments, we show that the two intermembrane space components Tic22 and MGD1 (E.C. 2.4.1.46) both engage the Toc machinery for crossing the outer envelope, whereas their pathways diverge thereafter. Although MGD1 appears to at least partly cross the inner envelope, Tic22 very likely reaches its mature form in the intermembrane space without involving stromal components. Thus, different pathways for intermembrane space targeting probably exist in chloroplasts.

  3. Circadian oscillations of cytosolic and chloroplastic free calcium in plants

    NASA Technical Reports Server (NTRS)

    Johnson, C. H.; Knight, M. R.; Kondo, T.; Masson, P.; Sedbrook, J.; Haley, A.; Trewavas, A.

    1995-01-01

    Tobacco and Arabidopsis plants, expressing a transgene for the calcium-sensitive luminescent protein apoaequorin, revealed circadian oscillations in free cytosolic calcium that can be phase-shifted by light-dark signals. When apoaequorin was targeted to the chloroplast, circadian chloroplast calcium rhythms were likewise observed after transfer of the seedlings to constant darkness. Circadian oscillations in free calcium concentrations can be expected to control many calcium-dependent enzymes and processes accounting for circadian outputs. Regulation of calcium flux is therefore fundamental to the organization of circadian systems.

  4. Oxidation versus reductive detoxification of SO sub 2 by chloroplasts

    SciTech Connect

    Ghisi, R.; Dittrich, A.P.M.; Heber, U. )

    1990-03-01

    Intact chloroplasts isolated from spinach (Spinacia oleracea L. cv Yates) both oxidized and reduced added sulfite in the light. Oxidation was fast only when endogenous superoxide dismutase was inhibited by cyanide. It was largely suppressed by scavengers of oxygen radicals. After addition of O-acetylserine, chloroplasts reduced sulfite to cysteine and exhibited sulfite-dependent oxygen evolution. Cysteine synthesis from sulfite was faster than from sulfate. The results are discussed in relation to species-specific differences in the phytotoxicity of SO{sub 2}.

  5. Chloroplast membranes of the green alga Acetabularia mediterranea. II. Topography of the chloroplast membrane.

    PubMed

    Apel, K; Miller, K R; Bogorad, L; Miller, G J

    1976-12-01

    The localization of the chlorophyll-protein complexes inside the thylakoid membrane of Acetabularia mediterranea was determined by fractionating the chloroplast membrane with EDTA and Triton X-100, by using pronase treatment, and by labeling the surface-exposed proteins with 125I. The effects of the various treatments were established by electrophoresis of the solubilized membrane fractions and electron microscopy. After EDTA and pronase treatment, the membrane structure was still intact. Only the two chlorophyll-protein complexes of 67,000 and 152,000 daltons and an additional polypeptides were found in the membrane before the EDTA and pronase treatment. The 125,000 dalton complex seems to be buried inside the lipid layer. The 23,000 dalton subunit of the 67,000 dalton complex is largely exposed to the surface of the EDTA-insoluble membrane and only the chlorophyll-binding subunit of 21,500 daltons is buried inside the lipid layer.

  6. Academic Subenvironments and Differential Patterns of Self-Perceived Growth during College: A Test of Holland's Theory. ASHE Annual Meeting Paper.

    ERIC Educational Resources Information Center

    Smart, John C.

    Academic departments exert a powerful influence on students by recruitment of distinctive personality types into academic disciplines, and by a socialization process in which departments reward students for the display of attitudes in accordance with the norms of their disciplines. This study examined the differential patterns of student growth…

  7. A mammalian cytochrome fused to a chloroplast transit peptide is a functional haemoprotein and is imported into isolated chloroplasts.

    PubMed Central

    Liu, Y Y; Kaderbhai, N; Kaderbhai, M A

    2000-01-01

    The small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is a major chloroplast stromal protein that is cytosolically synthesized as a precursor with an N-terminal extension, known as the transit sequence or transit peptide (Tp). The Tp is essential for the post-translational uptake of the precursor by the chloroplast. The Tp is thought to influence the conformation of the precursor protein and to facilitate polypeptide translocation across the chloroplast envelope barrier via a Tp-selective translocon. To address these issues we have devised a novel strategy to generate substrate amounts of a chloroplast targeting sequence as a fusion with the chromogenic globular domain of cytochrome b(5) (Cyt). The chimaeric protein is an ideal probe for investigating the conformation of a preprotein and events surrounding protein import into isolated chloroplasts. The Cyt of liver endoplasmic reticulum was fused at its N-terminus with the Tp of the small subunit of Rubisco of Pisum sativum (pea). To enhance its production by clearance from the cytoplasm of Escherichia coli, the chimaera was engineered by further N-terminal linkage of a prokaryotic secretory signal. Expression of this tripartite fusion resulted in mg quantities of the signal sequence-processed Tp-Cyt protein, which was eventually targeted to the membranes. The chromogenic nature of the chimaera and its localization to the bacterial membrane facilitated the biochemical isolation of the precursor in a soluble and functional form. The purified preprotein displayed spectral and enzymic properties that were indistinguishable from the native parental Cyt, implying an absence of observable influence of the Tp on the conformation of the haemoprotein. The chimaeric precursor was imported into the stroma of the isolated chloroplasts in a dose-dependent manner. Import was also strongly dependent upon exogenously supplied ATP. The stromally imported chimaeric precursor protein was processed to a size

  8. Myosin inhibitors block accumulation movement of chloroplasts in Arabidopsis thaliana leaf cells.

    PubMed

    Paves, H; Truve, E

    2007-01-01

    Chloroplasts alter their distribution within plant cells depending on the external light conditions. Myosin inhibitors 2,3-butanedione monoxime (BDM), N-ethylmaleimide (NEM), and 1-(5-iodonaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine hydrochloride (ML-7) were used to study the possible role of myosins in chloroplast photorelocation in Arabidopsis thaliana mesophyll cells. None of these agents had an effect on the chloroplast high-fluence-rate avoidance movement but all of the three myosin inhibitors blocked the accumulation movement of chloroplasts after a high-fluence-rate irradiation of the leaves. The results suggest that myosins have a role in A. thaliana chloroplast photorelocation.

  9. Silencing of NbCEP1 encoding a chloroplast envelope protein containing 15 leucine-rich-repeats disrupts chloroplast biogenesis in Nicotiana benthamiana.

    PubMed

    Jeon, Young; Hwang, A-Reum; Hwang, Inhwan; Pai, Hyun-Sook

    2010-02-28

    We characterized the physiological functions of Nicotiana benthamiana Chloroplast Envelope Protein 1 (NbCEP1) in Nicotiana benthamiana. NbCEP1 contains a chloroplast transit peptide and a single transmembrane domain at the N terminus, and most of its protein coding region is comprised of 15 leucine-rich-repeats (LRRs). The NbCEP1 gene is expressed in both aerial and underground plant tissues, and is induced by light. A GFP fusion protein of full length NbCEP1 was targeted to the chloroplast envelope and co-localized with OEP7:RFP, a marker protein for the chloroplast envelope. A fusion protein consisting of GFP and the NbCEP1 transit peptide mainly localized in the chloroplast stroma. Reduction of NbCEP1 expression by virus-induced gene silencing resulted in a leaf yellowing phenotype without much affecting overall plant growth. At the cellular level, depletion of NbCEP1 severely influenced chloroplast development, reducing both the number and size of the chloroplasts. Interestingly, mitochondrial development was also impaired, possibly an indirect effect of chloroplast ablation. A deficiency in NbCEP1 activity decreased the chlorophyll and carotenoid levels. Our results suggest that NbCEP1 plays a critical function, possibly through protein-protein interactions mediated by its LRRs, in chloroplast development in N. benthamiana.

  10. WHITE PANICLE1, a Val-tRNA Synthetase Regulating Chloroplast Ribosome Biogenesis in Rice, Is Essential for Early Chloroplast Development1[OPEN

    PubMed Central

    Wang, Chunming; Zheng, Ming; Lyu, Jia; Xu, Yang; Li, Xiaohui; Niu, Mei; Long, Wuhua; Wang, Di; Wang, Yihua; Wan, Jianmin

    2016-01-01

    Chloroplasts and mitochondria contain their own genomes and transcriptional and translational systems. Establishing these genetic systems is essential for plant growth and development. Here we characterized a mutant form of a Val-tRNA synthetase (OsValRS2) from Oryza sativa that is targeted to both chloroplasts and mitochondria. A single base change in OsValRS2 caused virescent to albino phenotypes in seedlings and white panicles at heading. We therefore named this mutant white panicle 1 (wp1). Chlorophyll autofluorescence observations and transmission electron microscopy analyses indicated that wp1 mutants are defective in early chloroplast development. RNA-seq analysis revealed that expression of nuclear-encoded photosynthetic genes is significantly repressed, while expression of many chloroplast-encoded genes also changed significantly in wp1 mutants. Western-blot analyses of chloroplast-encoded proteins showed that chloroplast protein levels were reduced in wp1 mutants, although mRNA levels of some genes were higher in wp1 than in wild type. We found that wp1 was impaired in chloroplast ribosome biogenesis. Taken together, our results show that OsValRS2 plays an essential role in chloroplast development and regulating chloroplast ribosome biogenesis. PMID:26839129

  11. WHITE PANICLE1, a Val-tRNA Synthetase Regulating Chloroplast Ribosome Biogenesis in Rice, Is Essential for Early Chloroplast Development.

    PubMed

    Wang, Yunlong; Wang, Chunming; Zheng, Ming; Lyu, Jia; Xu, Yang; Li, Xiaohui; Niu, Mei; Long, Wuhua; Wang, Di; Wang, HaiYang; Terzaghi, William; Wang, Yihua; Wan, Jianmin

    2016-04-01

    Chloroplasts and mitochondria contain their own genomes and transcriptional and translational systems. Establishing these genetic systems is essential for plant growth and development. Here we characterized a mutant form of a Val-tRNA synthetase (OsValRS2) from Oryza sativa that is targeted to both chloroplasts and mitochondria. A single base change in OsValRS2 caused virescent to albino phenotypes in seedlings and white panicles at heading. We therefore named this mutant white panicle 1 (wp1). Chlorophyll autofluorescence observations and transmission electron microscopy analyses indicated that wp1 mutants are defective in early chloroplast development. RNA-seq analysis revealed that expression of nuclear-encoded photosynthetic genes is significantly repressed, while expression of many chloroplast-encoded genes also changed significantly in wp1 mutants. Western-blot analyses of chloroplast-encoded proteins showed that chloroplast protein levels were reduced in wp1 mutants, although mRNA levels of some genes were higher in wp1 than in wild type. We found that wp1 was impaired in chloroplast ribosome biogenesis. Taken together, our results show that OsValRS2 plays an essential role in chloroplast development and regulating chloroplast ribosome biogenesis. © 2016 American Society of Plant Biologists. All Rights Reserved.

  12. Two kinesin-like proteins mediate actin-based chloroplast movement in Arabidopsis thaliana.

    PubMed

    Suetsugu, Noriyuki; Yamada, Noboru; Kagawa, Takatoshi; Yonekura, Hisashi; Uyeda, Taro Q P; Kadota, Akeo; Wada, Masamitsu

    2010-05-11

    Organelle movement is essential for efficient cellular function in eukaryotes. Chloroplast photorelocation movement is important for plant survival as well as for efficient photosynthesis. Chloroplast movement generally is actin dependent and mediated by blue light receptor phototropins. In Arabidopsis thaliana, phototropins mediate chloroplast movement by regulating short actin filaments on chloroplasts (cp-actin filaments), and the chloroplast outer envelope protein CHUP1 is necessary for cp-actin filament accumulation. However, other factors involved in cp-actin filament regulation during chloroplast movement remain to be determined. Here, we report that two kinesin-like proteins, KAC1 and KAC2, are essential for chloroplasts to move and anchor to the plasma membrane. A kac1 mutant showed severely impaired chloroplast accumulation and slow avoidance movement. A kac1kac2 double mutant completely lacked chloroplast photorelocation movement and showed detachment of chloroplasts from the plasma membrane. KAC motor domains are similar to those of the kinesin-14 subfamily (such as Ncd and Kar3) but do not have detectable microtubule-binding activity. The C-terminal domain of KAC1 could interact with F-actin in vitro. Instead of regulating microtubules, KAC proteins mediate chloroplast movement via cp-actin filaments. We conclude that plants have evolved a unique mechanism to regulate actin-based organelle movement using kinesin-like proteins.

  13. Chloroplast Biogenesis: Control of Plastid Development, Protein Import, Division and Inheritance

    PubMed Central

    Sakamoto, Wataru; Miyagishima, Shin-ya; Jarvis, Paul

    2008-01-01

    The chloroplast is a multi-copy cellular organelle that not only performs photosynthesis but also synthesizes amino acids, lipids and phytohormones. The plastid also responds to environmental stimuli such as gravitropism. Biogenesis of chloroplasts is initiated from proplastids in shoot meristems, and involves a series of important events. In the last decade, considerable progress has been made towards understanding various aspects of chloroplast biogenesis at the molecular level, via studies in model systems such as Arabidopsis. This review focuses on two important aspects of chloroplast biogenesis, synthesis/assembly and division/transmission. Chloroplasts originated through endosymbiosis from an ancestor of extant cyanobacteria, and thus contain their own genomes. DNA in chloroplasts is organized into complexes with proteins, and these are called nucleoids. The synthesis of chloroplast proteins is regulated at various steps. However, a majority of proteins are synthesized in the cytosol, and their proper import into chloroplast compartments is a prerequisite for chloroplast development. Fundamental aspects of plastid gene expression/regulation and chloroplast protein transport are described, together with recent proteome analyses of the organelle. Chloroplasts are not de novo synthesized, but instead are propagated from pre-existing plastids. In addition, plastids are transmitted from generation to generation with a unique mode of inheritance. Our current knowledge on the division machinery and the inheritance of plastids is described. PMID:22303235

  14. DipM is required for peptidoglycan hydrolysis during chloroplast division.

    PubMed

    Miyagishima, Shin-ya; Kabeya, Yukihiro; Sugita, Chieko; Sugita, Mamoru; Fujiwara, Takayuki

    2014-03-06

    Chloroplasts have evolved from a cyanobacterial endosymbiont and their continuity has been maintained over time by chloroplast division, a process which is performed by the constriction of a ring-like division complex at the division site. The division complex has retained certain components of the cyanobacterial division complex, which function inside the chloroplast. It also contains components developed by the host cell, which function outside of the chloroplast and are believed to generate constrictive force from the cytosolic side, at least in red algae and Viridiplantae. In contrast to the chloroplasts in these lineages, those in glaucophyte algae possess a peptidoglycan layer between the two envelope membranes, as do cyanobacteria. In this study, we show that chloroplast division in the glaucophyte C. paradoxa does not involve any known chloroplast division proteins of the host eukaryotic origin, but rather, peptidoglycan spitting and probably the outer envelope division process rely on peptidoglycan hydrolyzing activity at the division site by the DipM protein, as in cyanobacterial cell division. In addition, we found that DipM is required for normal chloroplast division in the moss Physcomitrella patens. These results suggest that the regulation of peptidoglycan splitting was essential for chloroplast division in the early evolution of chloroplasts and this activity is likely still involved in chloroplast division in Viridiplantae.

  15. Diversity of a ribonucleoprotein family in tobacco chloroplasts: two new chloroplast ribonucleoproteins and a phylogenetic tree of ten chloroplast RNA-binding domains.

    PubMed Central

    Ye, L H; Li, Y Q; Fukami-Kobayashi, K; Go, M; Konishi, T; Watanabe, A; Sugiura, M

    1991-01-01

    Two new ribonucleoproteins (RNPs) have been identified from a tobacco chloroplast lysate. These two proteins (cp29A and cp29B) are nuclear-encoded and have a less affinity to single-stranded DNA as compared with three other chloroplast RNPs (cp28, cp31 and cp33) previously isolated. DNA sequencing revealed that both contain two consensus sequence-type homologous RNA-binding domains (CS-RBDs) and a very acidic amino-terminal domain but shorter than that of cp28, cp31 and cp33. Comparison of cp29A and cp29B showed a 19 amino acid insertion in the region separating the two CS-RBDs in cp29B. This insertion results in three tandem repeats of a glycine-rich sequence of 10 amino acids, which is a novel feature in RNPs. The two proteins are encoded by different single nuclear genes and no alternatively spliced transcripts could be identified. We constructed a phylogenetic tree for the ten chloroplast CS-RBDs. These results suggest that there is a sizable RNP family in chloroplasts and the diversity was mainly generated through a series of gene duplications rather than through alternative pre-mRNA splicing. The gene for cp29B contains three introns. The first and second introns interrupt the first CS-RBD and the third intron does the second CS-RBD. The position of the first intron site is the same as that in the human hnRNP A1 protein gene. Images PMID:1721701

  16. Mutation of a chloroplast-targeting signal in Alternanthera mosaic virus TGB3 impairs cell-to-cell movement and eliminates long-distance virus movement.

    PubMed

    Lim, Hyoun-Sub; Vaira, Anna Maria; Bae, Hanhong; Bragg, Jennifer N; Ruzin, Steven E; Bauchan, Gary R; Dienelt, Margaret M; Owens, Robert A; Hammond, John

    2010-08-01

    Cell-to-cell movement of potexviruses requires coordinated action of the coat protein and triple gene block (TGB) proteins. The structural properties of Alternanthera mosaic virus (AltMV) TGB3 were examined by methods differentiating between signal peptides and transmembrane domains, and its subcellular localization was studied by Agrobacterium-mediated transient expression and confocal microscopy. Unlike potato virus X (PVX) TGB3, AltMV TGB3 was not associated with the endoplasmic reticulum, and accumulated preferentially in mesophyll cells. Deletion and site-specific mutagenesis revealed an internal signal VL(17,18) of TGB3 essential for chloroplast localization, and either deletion of the TGB3 start codon or alteration of the chloroplast-localization signal limited cell-to-cell movement to the epidermis, yielding a virus that was unable to move into the mesophyll layer. Overexpression of AltMV TGB3 from either AltMV or PVX infectious clones resulted in veinal necrosis and vesiculation at the chloroplast membrane, a cytopathology not observed in wild-type infections. The distinctive mesophyll and chloroplast localization of AltMV TGB3 highlights the critical role played by mesophyll targeting in virus long-distance movement within plants.

  17. Complete Chloroplast Genome Sequence of Dendrobium nobile from Northeastern India

    PubMed Central

    Parameswaran, Sriram; Sundar, Durai

    2016-01-01

    The orchid species Dendrobium nobile belonging to the family Orchidaceae and genus Dendrobium (a vast genus that encompasses nearly 1,200 species) has an herbal medicinal history of about 2000 years in east and south Asian countries. Here, we report the complete chloroplast genome sequence of D. nobile from northeastern India for the first time. PMID:27795255

  18. Characterization of polymorphic SSRs among Prunus chloroplast genomes

    USDA-ARS?s Scientific Manuscript database

    An in silico mining process yielded 80, 75, and 78 microsatellites in the chloroplast genome of Prunus persica, P. kansuensis, and P. mume. A and T repeats were predominant in the three genomes, accounting for 67.8% on average and most of them were successful in primer design. For the 80 P. persica ...

  19. The molecular integrity of chloroplast ribosomal ribonucleic acid.

    PubMed

    Leaver, C J; Ingle, J

    1971-06-01

    Instability of chloroplast rRNA has been observed with essentially all chloroplast RNA preparations. This paper describes experiments that show that, under normal conditions of preparation and fractionation, only the heavy chloroplast component (mol.wt. 1.1x10(6)) is unstable, the light chloroplast rRNA (mol.wt. 0.56x10(6)) and the cytoplasmic rRNA species (mol.wt. 1.3x10(6) and 0.70x10(6)) being stable. The stability of the 1.1x10(6)-mol. wt. molecule varies with different plant species, as also does the size and the number of fragments produced. Cleavages in three particular regions of the molecule are very frequent within the range of tissues studied. The 1.1x10(6)-mol.wt. rRNA is, however, stabilized by the presence of Mg(2+) during the preparation and fractionation of the RNA.

  20. GRANULES ASSOCIATED WITH THE CHLOROPLAST LAMELLAE OF PORPHYRIDIUM CRUENTUM

    PubMed Central

    Gantt, E.; Conti, S. F.

    1966-01-01

    Small granules with a diameter of approximately 350 A are attached to the chloroplast lamellae of the red alga Porphyridium cruentum. To some extent, their size depends on the culture conditions and the age of the cell. It was possible to preserve the granules only with aldehyde prefixation. It can be seen that fixed or negatively stained granules are comprised of smaller subunits. The granules are arranged regularly on the lamellae in repeating rows with a center-to-center granule distance of 400 to 500 A. Attempts at characterization of these chloroplast granules revealed that they are resistant to hydrolysis by ribonuclease and appear to be structurally unaffected by methanol-acetone extraction. Because of their close association with the chloroplast lamellae, they are considered as possible sites of phycobilin concentration. This possibility is supported by two observations: when the phycobilins are removed, the granules disappear; and, when the chlorophyll and stainable membrane portions are selectively removed, the phycobilins and granules are still present. It was found that all other marine red algae examined had granules which were associated with the chloroplast lamellae. PMID:5962937

  1. Chloroplast microsatellite markers for Artocarpus (Moraceae) developed from transcriptome sequences

    USDA-ARS?s Scientific Manuscript database

    Premise of the study: Chloroplast microsatellite loci were characterized from transcriptomes of Artocarpus (A.) altilis (breadfruit) and A. camansi (breadnut). They were tested in A. odoratissimus (terap) and A. altilis and evaluated in silico for two congeners. Methods and Results: 15 simple seque...

  2. Protein disorder in plants: a view from the chloroplast

    PubMed Central

    2012-01-01

    Background The intrinsically unstructured state of some proteins, observed in all living organisms, is essential for basic cellular functions. In this field the available information from plants is limited but it has been reached a point where these proteins can be comprehensively classified on the basis of disorder, function and evolution. Results Our analysis of plant genomes confirms that nuclear-encoded proteins follow the same trend than other multi-cellular eukaryotes; however, chloroplast- and mitochondria- encoded proteins conserve the patterns of Archaea and Bacteria, in agreement with their phylogenetic origin. Based on current knowledge about gene transference from the chloroplast to the nucleus, we report a strong correlation between the rate of disorder of transferred and nuclear-encoded proteins, even for polypeptides that play functional roles back in the chloroplast. We further investigate this trend by reviewing the set of chloroplast ribosomal proteins, one of the most representative transferred gene clusters, finding that the ribosomal large subunit, assembled from a majority of nuclear-encoded proteins, is clearly more unstructured than the small one, which integrates mostly plastid-encoded proteins. Conclusions Our observations suggest that the evolutionary dynamics of the plant nucleus adds disordered segments to genes alike, regardless of their origin, with the notable exception of proteins currently encoded in both genomes, probably due to functional constraints. PMID:22970728

  3. Transport Across Chloroplast Membranes: Optimizing Photosynthesis for Adverse Environmental Conditions.

    PubMed

    Pottosin, Igor; Shabala, Sergey

    2016-03-07

    Chloroplasts are central to solar light harvesting and photosynthesis. Optimal chloroplast functioning is vitally dependent on a very intensive traffic of metabolites and ions between the cytosol and stroma, and should be attuned for adverse environmental conditions. This is achieved by an orchestrated regulation of a variety of transport systems located at chloroplast membranes such as porines, solute channels, ion-specific cation and anion channels, and various primary and secondary active transport systems. In this review we describe the molecular nature and functional properties of the inner and outer envelope and thylakoid membrane channels and transporters. We then discuss how their orchestrated regulation affects thylakoid structure, electron transport and excitation energy transfer, proton-motive force partition, ion homeostasis, stromal pH regulation, and volume regulation. We link the activity of key cation and anion transport systems with stress-specific signaling processes in chloroplasts, and discuss how these signals interact with the signals generated in other organelles to optimize the cell performance, with a special emphasis on Ca(2+) and reactive oxygen species signaling. Copyright © 2016 The Author. Published by Elsevier Inc. All rights reserved.

  4. Structure of "Arabidopsis" chloroplastic monothiol glutaredoxin AtGRXcp

    USDA-ARS?s Scientific Manuscript database

    Monothiol glutaredoxins (Grxs) play important roles in maintaining redox homeostasis in living cells and are conserved across species. "Arabidopsis thaliana" monothiol glutaredoxin AtGRXcp, is critical for protection from oxidative stress in chloroplasts. The crystal structure of AtGRXcp has been de...

  5. Protein disorder in plants: a view from the chloroplast.

    PubMed

    Yruela, Inmaculada; Contreras-Moreira, Bruno

    2012-09-13

    The intrinsically unstructured state of some proteins, observed in all living organisms, is essential for basic cellular functions. In this field the available information from plants is limited but it has been reached a point where these proteins can be comprehensively classified on the basis of disorder, function and evolution. Our analysis of plant genomes confirms that nuclear-encoded proteins follow the same trend than other multi-cellular eukaryotes; however, chloroplast- and mitochondria- encoded proteins conserve the patterns of Archaea and Bacteria, in agreement with their phylogenetic origin. Based on current knowledge about gene transference from the chloroplast to the nucleus, we report a strong correlation between the rate of disorder of transferred and nuclear-encoded proteins, even for polypeptides that play functional roles back in the chloroplast. We further investigate this trend by reviewing the set of chloroplast ribosomal proteins, one of the most representative transferred gene clusters, finding that the ribosomal large subunit, assembled from a majority of nuclear-encoded proteins, is clearly more unstructured than the small one, which integrates mostly plastid-encoded proteins. Our observations suggest that the evolutionary dynamics of the plant nucleus adds disordered segments to genes alike, regardless of their origin, with the notable exception of proteins currently encoded in both genomes, probably due to functional constraints.

  6. Fatty acid phytyl ester synthesis in chloroplasts of Arabidopsis.

    PubMed

    Lippold, Felix; vom Dorp, Katharina; Abraham, Marion; Hölzl, Georg; Wewer, Vera; Yilmaz, Jenny Lindberg; Lager, Ida; Montandon, Cyrille; Besagni, Céline; Kessler, Felix; Stymne, Sten; Dörmann, Peter

    2012-05-01

    During stress or senescence, thylakoid membranes in chloroplasts are disintegrated, and chlorophyll and galactolipid are broken down, resulting in the accumulation of toxic intermediates, i.e., tetrapyrroles, free phytol, and free fatty acids. Chlorophyll degradation has been studied in detail, but the catabolic pathways for phytol and fatty acids remain unclear. A large proportion of phytol and fatty acids is converted into fatty acid phytyl esters and triacylglycerol during stress or senescence in chloroplasts. We isolated two genes (PHYTYL ESTER SYNTHASE1 [PES1] and PES2) of the esterase/lipase/thioesterase family of acyltransferases from Arabidopsis thaliana that are involved in fatty acid phytyl ester synthesis in chloroplasts. The two proteins are highly expressed during senescence and nitrogen deprivation. Heterologous expression in yeast revealed that PES1 and PES2 have phytyl ester synthesis and diacylglycerol acyltransferase activities. The enzymes show broad substrate specificities and can employ acyl-CoAs, acyl carrier proteins, and galactolipids as acyl donors. Double mutant plants (pes1 pes2) grow normally but show reduced phytyl ester and triacylglycerol accumulation. These results demonstrate that PES1 and PES2 are involved in the deposition of free phytol and free fatty acids in the form of phytyl esters in chloroplasts, a process involved in maintaining the integrity of the photosynthetic membrane during abiotic stress and senescence.

  7. Functional characterization of the chloroplast ferric chelate oxidoreductase enzyme.

    PubMed

    Solti, Adám; Müller, Brigitta; Czech, Viktória; Sárvári, Éva; Fodor, Ferenc

    2014-05-01

    Iron (Fe) has an essential role in the biosynthesis of chlorophylls and redox cofactors, and thus chloroplast iron uptake is a process of special importance. The chloroplast ferric chelate oxidoreductase (cFRO) has a crucial role in this process but it is poorly characterized. To study the localization and mechanism of action of cFRO, sugar beet (Beta vulgaris cv Orbis) chloroplast envelope fractions were isolated by gradient ultracentrifugation, and their purity was tested by western blotting against different marker proteins. The ferric chelate reductase (FCR) activity of envelope fractions was studied in the presence of NAD(P)H (reductants) and FAD coenzymes. Reduction of Fe(III)-ethylenediaminetetraacetic acid was monitored spectrophotometrically by the Fe(II)-bathophenanthroline disulfonate complex formation. FCR activity, that is production of free Fe(II) for Fe uptake, showed biphasic saturation kinetics, and was clearly associated only to chloroplast inner envelope (cIE) vesicles. The reaction rate was > 2.5 times higher with NADPH than with NADH, which indicates the natural coenzyme preference of cFRO activity and its dependence on photosynthesis. FCR activity of cIE vesicles isolated from Fe-deficient plants also showed clear biphasic kinetics, where the KM of the low affinity component was elevated, and thus this component was down-regulated.

  8. Chloroplast heterogeneity and historical admixture within the genus Malus.

    PubMed

    Volk, Gayle M; Henk, Adam D; Baldo, Angela; Fazio, Gennaro; Chao, C Thomas; Richards, Christopher M

    2015-07-01

    • The genus Malus represents a unique and complex evolutionary context in which to study domestication. Several Malus species have provided novel alleles and traits to the cultivars. The extent of admixture among wild Malus species has not been well described, due in part to limited sampling of individuals within a taxon.• Four chloroplast regions (1681 bp total) were sequenced and aligned for 412 Malus individuals from 30 species. Phylogenetic relationships were reconstructed using maximum parsimony. The distribution of chloroplast haplotypes among species was examined using statistical parsimony, phylogenetic trees, and a median-joining network.• Chloroplast haplotypes are shared among species within Malus. Three major haplotype-sharing networks were identified. One includes species native to China, Western North America, as well as Malus domestica Borkh, and its four primary progenitor species: M. sieversii (Ledeb.) M. Roem., M. orientalis Uglitzk., M. sylvestris (L.) Mill., and M. prunifolia (Willd.) Borkh; another includes five Chinese Malus species, and a third includes the three Malus species native to Eastern North America.• Chloroplast haplotypes found in M. domestica belong to a single, highly admixed network. Haplotypes shared between the domesticated apple and its progenitors may reflect historical introgression or the retention of ancestral polymorphisms. Multiple individuals should be sampled within Malus species to reveal haplotype heterogeneity, if complex maternal contributions to named species are to be recognized. © 2015 Botanical Society of America, Inc.

  9. The TOC complex: preprotein gateway to the chloroplast.

    PubMed

    Andrès, Charles; Agne, Birgit; Kessler, Felix

    2010-06-01

    Photosynthetic eukaryotes strongly depend on chloroplast metabolic pathways. Most if not all involve nuclear encoded proteins. These are synthesized as cytosolic preproteins with N-terminal, cleavable targeting sequences (transit peptide). Preproteins are imported by a major pathway composed of two proteins complexes: TOC and TIC (Translocon of the Outer and Inner membranes of the Chloroplasts, respectively). These selectively recognize the preproteins and facilitate their transport across the chloroplast envelope. The TOC core complex consists of three types of components, each belonging to a small family: Toc34, Toc75 and Toc159. Toc34 and Toc159 isoforms represent a subfamily of the GTPase superfamily. The members of the Toc34 and Toc159 subfamily act as GTP-dependent receptors at the chloroplast surface and distinct members of each occur in defined, substrate-specific TOC complexes. Toc75, a member of the Omp85 family, is conserved from prokaryotes and functions as the unique protein-conducting channel at the outer membrane. In this review we will describe the current state of knowledge regarding the composition and function of the TOC complex.

  10. Choline oxidation by intact chloroplasts isolated directly from spinach leaves

    SciTech Connect

    Weigel, P.; Hanson, A.D.

    1986-04-01

    Illuminated chloroplasts derived from spinach leaf protoplasts synthesize betaine from choline via the intermediate betaine aldehyde (BAL) (PNAS 82:3678). Photosynthetically active chloroplasts isolated directly from spinach leaves oxidized (/sup 14/C)choline in the light at rates 10 times higher (25-80 nmol/mg chl b) than protoplast-derived chloroplasts. Up to 20% of the (/sup 14/C)choline supplied during a 30 min incubation was oxidized in the light; the main product was (/sup 14/C)BAL. Rates of (/sup 14/C)choline oxidation in darkness were only 5-30% of rates in light. Light-dependent (/sup 14/C)choline oxidation was abolished by DCMU and 5 mM DTT. Pre-illumination of the chloroplasts did not promote (/sup 14/C)choline oxidation in darkness. The uncouplers nigericin and CCCP at concentrations which eliminated CO/sub 2/-dependent O/sub 2/ evolution did not affect (/sup 14/C)choline oxidation in the light. They hypothesize that (/sup 14/C)choline oxidation is not dependent upon light activation of an enzymatic system or upon the electrochemical proton gradient but requires an oxidant generated in the light.

  11. Choline oxidation by intact spinach chloroplasts. [Spinacia oleracea L

    SciTech Connect

    Weigel, P.; Lerma, C.; Hanson, A.D.

    1988-01-01

    Plants synthesize betaine by a two-step oxidation of choline (choline ..-->.. betaine aldehyde ..-->.. betaine). Protoplast-derived chloroplasts of spinach (Spinacia oleracea L.) carry out both reactions, more rapidly in light than in darkness. We investigated the light-stimulated oxidation of choline, using spinach chloroplasts isolated directly from leaves. The rates of choline oxidation obtained (dark and light rates: 10-50 and 100-300 nanomoles per hour per milligram chlorophyll, respectively) were approximately 20-fold higher than for protoplast-derived chloroplasts. Betaine aldehyde was the main product. Choline oxidation in darkness and light was suppressed by hypoxia. Neither uncouplers not the Calvin cycle inhibitor glyceraldehyde greatly affected choline oxidation in the light, and maximal choline oxidation was attained far below light saturation of CO/sub 2/ fixation. The light stimulation of choline oxidation was abolished by the PSII inhibitors DCMU and dibromothymoquinone, and was partially restored by adding reduced diaminodurene, an electron donor to PSI. Both methyl viologen and phenazine methosulfate prevented choline oxidation. Adding dihydroxyacetone phosphate, which can generate NADPH in organello, doubled the dark rate of choline oxidation. These results indicate that choline oxidation in chloroplasts requires oxygen, and reducing power generated from PSI. Enzymic reactions consistent with these requirements are discussed.

  12. Nuclear genes encoding plastid proteins expressed early in chloroplast development

    SciTech Connect

    Mullet, J.E.

    1991-01-01

    The overall objective of this grant was to characterize events which occur early in chloroplast biogenesis and to isolate nuclear genes encoding plastid proteins which are expressed during this developmental phase. In addition, the possible requirement of plastid transcription for the expression of the nuclear genes such as rbcS and cab was to be tested. The impetus for this research came from studies of chloroplast biogenesis in barley. We found that plastid DNA copy number was relatively high (120 copies/plastid vs 200 at maximal accumulation) in the meristematic region of the leaf base whereas plastid transcription activity was low in this plastid population. Later in chloroplast development transcription activity increased at least 5 fold per plastid or per template indicating that activation of plastid transcription occurred after most of the build up in plastid DNA per plastid. This suggested that activation of plastid DNA synthesis occurred early in chloroplast development and that nuclear genes involved in this activity must be regulated differently from genes such rbcS or cab which are expressed later in development. 3 refs., 7 figs.

  13. Chloroplast heterogeneity and historical admixture within the genus Malus

    USDA-ARS?s Scientific Manuscript database

    Premise of the study: We examined chloroplast DNA sequence variation in 412 samples representing 30 Malus species (including Malus x domestica Borkh.). Malus wild species are of particular interest for providing novel alleles and traits in apple breeding programs, yet the taxonomic status of these s...

  14. Targeting and biogenesis of transporters and channels in chloroplast envelope membranes: Unsolved questions.

    PubMed

    Oh, Young Jun; Hwang, Inhwan

    2015-07-01

    Chloroplasts produce carbohydrates, hormones, vitamins, amino acids, pigments, nucleotides, ATP, and secondary metabolites. Channels and transporters are required for the movement of molecules across the two chloroplast envelope membranes. These transporters and channel proteins are grouped into two different types, including β-barrel proteins and transmembrane-domain (TMD) containing proteins. Most β-barrel proteins are localized at the outer chloroplast membrane, and TMD-containing proteins are localized at the inner chloroplast membrane. Many of these transporters and channels are encoded by nuclear genes; therefore, they have to be imported into chloroplasts after translation on cytosolic ribosomes. These proteins should have specific targeting signals for their final destination in the chloroplast membrane and for assembly into specific complexes. In this review, we summarize recent progress in the identification, functional characterization, and biogenesis of transporters and channels at the chloroplast envelope membranes, and discuss outstanding questions regarding transporter and channel protein biogenesis.

  15. Chloroplast movement: dissection of events downstream of photo- and mechano-perception.

    PubMed

    Sato, Yoshikatsu; Kadota, Akeo; Wada, Masamitsu

    2003-02-01

    The study of chloroplast photorelocation movement is progressing rapidly now that mutants for chloroplast movement have become available in Arabidopsis thaliana. However, mechanistic approaches in cell biology still stand to elucidate the mechanisms and regulations of such movement. The fern Adiantum capillus-veneris and the moss Physcomitrella patens are particularly suitable materials for analyzing the kinetics of intracellular chloroplast movement. In these plants, chloroplast movement is induced by red light as well as blue light, mediated by phytochrome and blue light receptor, respectively. In this paper, we review the unique force-generating system for chloroplast motility in P. patens. In addition to light-induced chloroplast movement, we also summarize mechanically induced chloroplast movement in these plants and the motility systems involved. Finally, the different dependency of mechano- and photo-relocation movement on external Ca(2+) is discussed.

  16. Distribution pattern changes of actin filaments during chloroplast movement in Adiantum capillus-veneris.

    PubMed

    Tsuboi, Hidenori; Wada, Masamitsu

    2012-05-01

    Chloroplasts change their positions in a cell in response to light intensities. The photoreceptors involved in chloroplast photo-relocation movements and the behavior of chloroplasts during their migration were identified in our previous studies, but the mechanism of movement has yet to be clarified. In this study, the behavior of actin filaments under various light conditions was observed in Adiantum capillus-veneris gametophytes. In chloroplasts staying in one place under a weak light condition and not moving, circular structures composed of actin filaments were observed around the chloroplast periphery. In contrast, short actin filaments were observed at the leading edge of moving chloroplasts induced by partial cell irradiation. In the dark, the circular structures found under the weak light condition disappeared and then reappeared around the moving chloroplasts. Mutant analyses revealed that the disappearance of the circular actin structure was mediated by the blue light photoreceptor, phototropin2.

  17. Senescence-Associated Vacuoles, a Specific Lytic Compartment for Degradation of Chloroplast Proteins?

    PubMed

    Carrión, Cristian A; Martínez, Dana E; Costa, M Lorenza; Guiamet, Juan José

    2014-11-11

    Degradation of chloroplasts and chloroplast components is a distinctive feature of leaf senescence. In spite of its importance in the nutrient economy of plants, knowledge about the mechanism(s) involved in the breakdown of chloroplast proteins is incomplete. A novel class of vacuoles, "senescence-associated vacuoles" (SAVs), characterized by intense proteolytic activity appear during senescence in chloroplast-containing cells of leaves. Since SAVs contain some chloroplast proteins, they are candidate organelles to participate in chloroplast breakdown. In this review we discuss the characteristics of SAVs, and their possible involvement in the degradation of Rubisco, the most abundant chloroplast protein. Finally, SAVs are compared with other extra-plastidial protein degradation pathways operating in senescing leaves.

  18. Senescence-Associated Vacuoles, a Specific Lytic Compartment for Degradation of Chloroplast Proteins?

    PubMed Central

    Carrión, Cristian A.; Martínez, Dana E.; Costa, M. Lorenza; Guiamet, Juan José

    2014-01-01

    Degradation of chloroplasts and chloroplast components is a distinctive feature of leaf senescence. In spite of its importance in the nutrient economy of plants, knowledge about the mechanism(s) involved in the breakdown of chloroplast proteins is incomplete. A novel class of vacuoles, “senescence-associated vacuoles” (SAVs), characterized by intense proteolytic activity appear during senescence in chloroplast-containing cells of leaves. Since SAVs contain some chloroplast proteins, they are candidate organelles to participate in chloroplast breakdown. In this review we discuss the characteristics of SAVs, and their possible involvement in the degradation of Rubisco, the most abundant chloroplast protein. Finally, SAVs are compared with other extra-plastidial protein degradation pathways operating in senescing leaves. PMID:27135516

  19. Evolution of the Cp-Actin-based Motility System of Chloroplasts in Green Plants.

    PubMed

    Suetsugu, Noriyuki; Wada, Masamitsu

    2016-01-01

    During the course of green plant evolution, numerous light responses have arisen that optimize their growth under fluctuating light conditions. The blue light receptor phototropin mediates several photomovement responses at the tissue, cellular and organelle levels. Chloroplast photorelocation movement is one such photomovement response, and is found not only in most green plants, but also in some red algae and photosynthetic stramenopiles. In general, chloroplasts move toward weak light to maximally capture photosynthetically active radiation (the chloroplast accumulation response), and they move away from strong light to avoid photodamage (the avoidance response). In land plants, chloroplast movement is dependent on specialized actin filaments, chloroplast-actin filaments (cp-actin filaments). Through molecular genetic analysis using Arabidopsis thaliana, many molecular factors that regulate chloroplast photorelocation were identified. In this Perspective, we discuss the evolutionary history of the molecular mechanism for chloroplast photorelocation movement in green plants in view of cp-actin filaments.

  20. Reinvestigation of the triplet-minus-singlet spectrum of chloroplasts

    NASA Astrophysics Data System (ADS)

    Jávorfi, T.; Garab, G.; Razi Naqvi, K.

    2000-01-01

    A comparison of the triplet-minus-singlet (TmS) absorption spectrum of spinach chloroplasts, recorded some thirty years ago, with the more recently published TmS spectrum of isolated Chl a/ b LHCII (light-harvesting complexes associated with photosystem II of higher plants) shows that the two spectra are very similar, which is to be expected, since only the carotenoid pigments contribute to each spectrum. Be that as it may, the comparison also reveals a dissimilarity: photoexcitation of the sample does, or does not, affect the absorbance in the Qy region (650-700 nm), depending on whether the sample is a suspension of chloroplasts or of isolated LHCII. The Qy-signal in the TmS spectrum of LHCII decays, it should be noted, at the same rate as the rest of the difference spectrum, and its most prominent feature is a negative peak. As the carotenoids do not absorb in the Qy region, the presence of a signal in this region calls for an explanation: van der Vos, Carbonera and Hoff, the first to find as well as fathom the phenomenon, attributed the Qy-signal to a change, in the absorption spectrum of a chlorophyll a (Chl a) molecule, brought about by the presence of triplet excitation on a neighbouring carotenoid (Car). The difference in the behaviours of chloroplasts and LHCII, if reproducible, would imply that the Car triplets which give rise to the TmS spectrum of chloroplasts do not influence the absorption spectra of their Chl a neighbours. With a view to reaching a firm conclusion about this vexed issue, spinach chloroplasts and thylakoids have been examined with the aid of the same kinetic spectrometer as that used for investigating LHCII; the TmS spectra of both chloroplasts and thylakoids contain prominent bleaching signals centred at 680 nm, and the triplet decay time in each case is comparable to that of the Chl a/ b LHCII triplets. Results pertaining to other closely related systems are recalled, and it is concluded that, so far as the overall appearance of the

  1. Authentication Markers for Five Major Panax Species Developed via Comparative Analysis of Complete Chloroplast Genome Sequences.

    PubMed

    Nguyen, Van Binh; Park, Hyun-Seung; Lee, Sang-Choon; Lee, Junki; Park, Jee Young; Yang, Tae-Jin

    2017-08-02

    Ginseng represents a set of high-value medicinal plants of different species: Panax ginseng (Asian ginseng), Panax quinquefolius (American ginseng), Panax notoginseng (Chinese ginseng), Panax japonicus (Bamboo ginseng), and Panax vietnamensis (Vietnamese ginseng). Each species is pharmacologically and economically important, with differences in efficacy and price. Accordingly, an authentication system is needed to combat economically motivated adulteration of Panax products. We conducted comparative analysis of the chloroplast genome sequences of these five species, identifying 34-124 InDels and 141-560 SNPs. Fourteen InDel markers were developed to authenticate the Panax species. Among these, eight were species-unique markers that successfully differentiated one species from the others. We generated at least one species-unique marker for each of the five species, and any of the species can be authenticated by selection among these markers. The markers are reliable, easily detectable, and valuable for applications in the ginseng industry as well as in related research.

  2. Organic solvent extraction as a versatile procedure to identify hydrophobic chloroplast membrane proteins.

    PubMed

    Ferro, M; Seigneurin-Berny, D; Rolland, N; Chapel, A; Salvi, D; Garin, J; Joyard, J

    2000-10-01

    As a complementary approach to genome projects, proteomic analyses have been set up to identify new gene products. One of the major challenges in proteomics concerns membrane proteins, especially the minor ones. A procedure based on the differential extraction of membrane proteins in chloroform/methanol mixtures, was tested on the two different chloroplast membrane systems: envolope and thylakoid membranes. Combining the use of classical sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and mass spectrometry analyses, this procedure enabled identification of hydrophobic proteins. The propensity of hydrophobic proteins to partition in chloroform/methanol mixtures was directly correlated with the number of amino acid residues/number of putative transmembrane regions (Res/TM ratio). Regardless of the particular case of some lipid-interacting proteins, chloroform/methanol extractions allowed enrichment of hydrophobic proteins and exclusion of hydrophilic proteins from both membrane systems, thus demonstrating the versatility of the procedure.

  3. A search for factors influencing etioplast–chloroplast transition

    PubMed Central

    Pudelski, Birgit; Soll, Jürgen; Philippar, Katrin

    2009-01-01

    Chloroplast biogenesis in angiosperm plants requires the light-dependent transition from an etioplast stage. A key factor in this process is NADPH:protochlorophyllide oxidoreductase A (PORA), which catalyzes the light-dependent reduction of protochlorophyllide to chlorophyllide. In a recent study the chloroplast outer envelope channel OEP16 was described to be involved in etioplast to chloroplast transition by forming the translocation pore for the precursor protein of PORA [Pollmann et al. (2007) Proc Natl Acad Sci USA 104:2019–2023]. This hypothesis was based on the finding that a single OEP16.1 knockout mutant in Arabidopsis thaliana was severely affected during seedling de-etiolation and PORA protein was absent in etioplasts. In contrast, in our study the identical T-DNA insertion line greened normally and showed normal etioplast to chloroplast transition, and mature PORA was present in etioplasts [Philippar et al. (2007) Proc Natl Acad Sci USA 104:678–683]. To address these conflicting results regarding the function of OEP16.1 for PORA import, we analyzed several lines segregating from the original OEP16.1 T-DNA insertion line. Thereby we can unequivocally show that the loss of OEP16.1 neither correlates with impaired PORA import nor causes the observed de-etiolation phenotype. Furthermore, we found that the mutant line contains at least 2 additional T-DNA insertions in the genes for the extracellular polygalacturonase converter AroGP1 and the plastid-localized chorismate mutase CM1. However, detailed examination of the de-etiolation phenotype and a genomewide transcriptional analysis revealed no direct influence of these genes on etioplast to chloroplast transition in Arabidopsis cotyledons. PMID:19567834

  4. A search for factors influencing etioplast-chloroplast transition.

    PubMed

    Pudelski, Birgit; Soll, Jürgen; Philippar, Katrin

    2009-07-21

    Chloroplast biogenesis in angiosperm plants requires the light-dependent transition from an etioplast stage. A key factor in this process is NADPH:protochlorophyllide oxidoreductase A (PORA), which catalyzes the light-dependent reduction of protochlorophyllide to chlorophyllide. In a recent study the chloroplast outer envelope channel OEP16 was described to be involved in etioplast to chloroplast transition by forming the translocation pore for the precursor protein of PORA [Pollmann et al. (2007) Proc Natl Acad Sci USA 104:2019-2023]. This hypothesis was based on the finding that a single OEP16.1 knockout mutant in Arabidopsis thaliana was severely affected during seedling de-etiolation and PORA protein was absent in etioplasts. In contrast, in our study the identical T-DNA insertion line greened normally and showed normal etioplast to chloroplast transition, and mature PORA was present in etioplasts [Philippar et al. (2007) Proc Natl Acad Sci USA 104:678-683]. To address these conflicting results regarding the function of OEP16.1 for PORA import, we analyzed several lines segregating from the original OEP16.1 T-DNA insertion line. Thereby we can unequivocally show that the loss of OEP16.1 neither correlates with impaired PORA import nor causes the observed de-etiolation phenotype. Furthermore, we found that the mutant line contains at least 2 additional T-DNA insertions in the genes for the extracellular polygalacturonase converter AroGP1 and the plastid-localized chorismate mutase CM1. However, detailed examination of the de-etiolation phenotype and a genomewide transcriptional analysis revealed no direct influence of these genes on etioplast to chloroplast transition in Arabidopsis cotyledons.

  5. Desiccoplast-etioplast-chloroplast transformation under rehydration of desiccated poikilochlorophyllous Xerophyta humilis leaves in the dark and upon subsequent illumination.

    PubMed

    Solymosi, Katalin; Tuba, Zoltán; Böddi, Béla

    2013-04-15

    The transformation of desiccoplasts into etioplasts and the parallel appearance of protochlorophyllide (Pchlide) forms were observed with transmission electron microscopy and 77K fluorescence spectroscopy, when air-dried detached leaves of the poikilochlorophyllous desiccation tolerant plant Xerophyta humilis were floated in water in the dark. After 1 week of rehydration, pregranal plastids with newly synthesized prothylakoid (PT) lamellae and mainly non-photoactive Pchlide forms developed, while etioplasts with prolamellar bodies (PLBs) and photoactive, 655nm emitting Pchlide form accumulated primarily in the basal leaf regions after 2 weeks of regeneration. When these latter leaves were illuminated with continuous light for 3 days, the etioplasts transformed into regular chloroplasts and the fluorescence emission bands characteristic of green leaves appeared. These results show that, upon rehydration, the dehydrated chlorenchyma cells are able to regenerate pregranal plastids and etioplasts from desiccoplasts in the dark, which can transform into regular chloroplasts when they are illuminated. This means that the differentiation of pregranal plastids and etioplasts and their greening process is a basic property of fully differentiated cells of X. humilis. Consequently, these processes are not merely characteristic for seedlings with meristematic and differentiating young tissues. Copyright © 2013 Elsevier GmbH. All rights reserved.

  6. Genetic variation and species identification of Thai Boesenbergia (Zingiberaceae) analyzed by chloroplast DNA polymorphism.

    PubMed

    Techaprasan, Jiranan; Ngamriabsakul, Chatchai; Klinbunga, Sirawut; Chusacultanachai, Sudsanguan; Jenjittikul, Thaya

    2006-07-31

    Genetic variation and molecular phylogeny of 22 taxa representing 14 extant species and 3 unidentified taxa of Boesenbergia in Thailand and four outgroup species (Cornukaempferia aurantiflora, Hedychium biflorum, Kaempferia parviflora, and Scaphochlamys rubescens) were examined by sequencing of 3 chloroplast (cp) DNA regions (matK, psbA-trnH and petA-psbJ). Low interspecific genetic divergence (0.25-1.74%) were observed in these investigated taxa. The 50% majority-rule consensus tree constructed from combined chloroplast DNA sequences allocated Boesenbergia in this study into 3 different groups. Using psbA-1F/psbA-3R primers, an insertion of 491 bp was observed in B. petiolata. Restriction analysis of the amplicon (380-410 bp) from the remaining species with Rsa I further differentiated Boesenbergia to 2 groupings; I (B. basispicata, B. longiflora, B. longipes, B. plicata, B.pulcherrima, B. tenuispicata, B. thorelii, B. xiphostachya, Boesenbergia sp.1 and Boesenbergia sp.3; phylogenetic clade A) that possesses a Rsa I restriction site and II (B.curtisii, B. regalis, B. rotunda and Boesenbergia sp.2; phylogenetic clade B and B. siamensis; phylogenetic clade C) that lacks a restriction site of Rsa I. Single nucleotide polymorphism (SNP) and indels found can be unambiguously applied to authenticate specie-origin of all investigated samples and revealed that Boesenbergia sp.1, Boesenbergia sp.2 and B. pulcherrima (Mahidol University, Kanchanaburi), B. cf. pulcherrima1 (Prachuap Khiri Khan) and B. cf. pulcherrima2 (Thong Pha Phum, Kanchanaburi) are B. plicata, B. rotunda and B. pulcherrima, respectively. In addition, molecular data also suggested that Boesenbergia sp.3 should be further differentiated from B. longiflora and regarded as a newly unidentified Boesenbergia species.

  7. Chloroplast biogenesis during rehydration of the resurrection plant Xerophyta humilis: parallels to the etioplast-chloroplast transition.

    PubMed

    Ingle, Robert A; Collett, Helen; Cooper, Keren; Takahashi, Yuichiro; Farrant, Jill M; Illing, Nicola

    2008-12-01

    De-etiolation of dark-grown seedlings is a commonly used experimental system to study the mechanisms of chloroplast biogenesis, including the stacking of thylakoid membranes into grana, the response of the nuclear-chloroplast transcriptome to light, and the ordered synthesis and assembly of photosystem II (PSII). Here, we present the xeroplast to chloroplast transition during rehydration of the resurrection plant Xerophyta humilis as a novel system for studying chloroplast biogenesis, and investigate the role of light in this process. Xeroplasts are characterized by the presence of numerous large and small membrane-bound vesicles and the complete absence of thylakoid membranes. While the initial assembly of stromal thylakoid membranes occurs independently of light, the formation of grana is light dependent. Recovery of photosynthetic activity is rapid in plants rehydrated in the light and correlates with the light-dependent synthesis of the D1 protein, but does not require de novo chlorophyll biosynthesis. Light-dependent synthesis of the chlorophyll-binding protein Lhcb2 and digalactosyldiacylglycerol synthase 1 correlated with the formation of grana and with the increased PSII activity. Our results suggest that the molecular mechanisms underlying photomorphogenic development may also function in desiccation tolerance in poikilochlorophyllous resurrection plants.

  8. Chloroplast Genome Sequence of the Moss Tortula ruralis: Gene Content and Structural Arrangement Relative to Other Green Plant Chloroplast Genomes

    USDA-ARS?s Scientific Manuscript database

    Tortula ruralis, a widely distributed moss species in the family Pottiaceae, is increasingly being used as a model organism for the study of desiccation tolerance and mechanisms of cellular repair. In this paper, we present the chloroplast genome sequence of Tortula ruralis, only the second publishe...

  9. The Chloroplast Genome Sequence of Scutellaria baicalensis Provides Insight into Intraspecific and Interspecific Chloroplast Genome Diversity in Scutellaria.

    PubMed

    Jiang, Dan; Zhao, Zhenyu; Zhang, Teng; Zhong, Wenhao; Liu, Chunsheng; Yuan, Qingjun; Huang, Luqi

    2017-09-13

    Scutellaria baicalensis Georgi (Lamiaceae) is the source of the well-known traditional Chinese medicine "HuangQin" (Radix Scutellariae). Natural sources of S. baicalensis are rapidly declining due to high market demand and overexploitation. Moreover, the commercial products of Radix Scutellariae have often been found to contain adulterants in recent years, which may give rise to issues regarding drug efficacy and safety. In this study, we developed valuable chloroplast molecular resources by comparing intraspecific and interspecific chloroplast genome. The S. baicalensis chloroplast genome is a circular molecule consisting of two single-copy regions separated by a pair of inverted repeats. Comparative analyses of three Scutellaria chloroplast genomes revealed six variable regions (trnH-psbA, trnK-rps16, petN-psbM, trnT-trnL, petA-psbJ, and ycf1) that could be used as DNA barcodes. There were 25 single nucleotide polymorphisms(SNPs) and 29 indels between the two S. baicalensis genotypes. All of the indels occurred within non-coding regions. Phylogenetic analysis suggested that Scutellarioideae is a sister taxon to Lamioideae. These resources could be used to explore the variation present in Scutellaria populations and for further evolutionary, phylogenetic, barcoding and genetic engineering studies, in addition to effective exploration and conservation of S. baicalensis.

  10. Redirecting the Cyanobacterial Bicarbonate Transporters BicA and SbtA to the Chloroplast Envelope: Soluble and Membrane Cargos Need Different Chloroplast Targeting Signals in Plants

    PubMed Central

    Rolland, Vivien; Badger, Murray R.; Price, G. Dean

    2016-01-01

    Most major crops used for human consumption are C3 plants, which yields are limited by photosynthetic inefficiency. To circumvent this, it has been proposed to implement the cyanobacterial CO2-concentrating mechanism (CCM), principally consisting of bicarbonate transporters and carboxysomes, into plant chloroplasts. As it is currently not possible to recover homoplasmic transplastomic monocots, foreign genes must be introduced in these plants via nuclear transformation. Consequently, it is paramount to ensure that resulting proteins reach the appropriate sub-cellular compartment, which for cyanobacterial transporters BicA and SbtA, is the chloroplast inner-envelope membrane (IEM). At present, targeting signals to redirect large transmembrane proteins from non-chloroplastic organisms to plant chloroplast envelopes are unknown. The goal of this study was to identify such signals, using agrobacteria-mediated transient expression and confocal microscopy to determine the sub-cellular localization of ∼37 GFP-tagged chimeras. Initially, fragments of chloroplast proteins known to target soluble cargos to the stroma were tested for their ability to redirect BicA, but they proved ineffective. Next, different N-terminal regions from Arabidopsis IEM transporters were tested. We demonstrated that the N-terminus of AtHP59, AtPLGG1 or AtNTT1 (92–115 amino acids), containing a cleavable chloroplast transit peptide (cTP) and a membrane protein leader (MPL), was sufficient to redirect BicA or SbtA to the chloroplast envelope. This constitutes the first evidence that nuclear-encoded transmembrane proteins from non-chloroplastic organisms can be targeted to the envelope of plant chloroplasts; a finding which represents an important advance in chloroplast engineering by opening up the door to further manipulation of the chloroplastic envelope. PMID:26973659

  11. Chloroplast phosphoglycerate kinase is involved in the targeting of Bamboo mosaic virus to chloroplasts in Nicotiana benthamiana plants.

    PubMed

    Cheng, Shun-Fang; Huang, Ying-Ping; Chen, Li-Hung; Hsu, Yau-Heiu; Tsai, Ching-Hsiu

    2013-12-01

    The Bamboo mosaic virus (BaMV) is a positive-sense, single-stranded RNA virus. Previously, we identified that the chloroplast phosphoglycerate kinase (chl-PGK) from Nicotiana benthamiana is one of the viral RNA binding proteins involved in the BaMV infection cycle. Because chl-PGK is transported to the chloroplast, we hypothesized that chl-PGK might be involved in viral RNA localization in the chloroplasts. To test this hypothesis, we constructed two green fluorescent protein (GFP)-fused mislocalized PGK mutants, the transit peptide deletion mutant (NO TRANSIT PEPTIDE [NOTP]-PGK-GFP) and the nucleus location mutant (nuclear location signal [NLS]-PGK-GFP). Using confocal microscopy, we demonstrated that NOTP-PGK-GFP and NLS-PGK-GFP are localized in the cytoplasm and nucleus, respectively, in N. benthamiana plants. When NOTP-PGK-GFP and NLS-PGK-GFP are transiently expressed, we observed a reduction in BaMV coat protein accumulation to 47% and 27% that of the wild-type PGK-GFP, respectively. To localize viral RNA in infected cells, we employed the interaction of NLS-GFP-MS2 (phage MS2 coat protein) with the modified BaMV RNA containing the MS2 coat protein binding sequence. Using confocal microscopy, we observed that BaMV viral RNA localizes to chloroplasts. Furthermore, elongation factor1a fused with the transit peptide derived from chl-PGK or with a Rubisco small subunit can partially restore BaMV accumulation in NbPGK1-knockdown plants by helping BaMV target chloroplasts.

  12. Purine biosynthetic enzyme ATase2 is involved in the regulation of early chloroplast development and chloroplast gene expression in Arabidopsis.

    PubMed

    Yang, Zhipan; Shang, Zengzhen; Wang, Lei; Lu, Qingtao; Wen, Xiaogang; Chi, Wei; Zhang, Lixin; Lu, Congming

    2015-12-01

    To investigate the molecular mechanism of chloroplast biogenesis and development, we characterized an Arabidopsis mutant (dg169, delayed greening 169) which showed growth retardation and delayed greening phenotype in leaves. Newly emerged chlorotic leaves recovered gradually with leaf development in the mutant, and the mature leaves showed similar phenotype to those of wild-typewild-type plants. Compared with wild-type, the chloroplasts were oval-shaped and smaller and the thylakoid membranes were less abundant in yellow section of young leaves of dg169. In addition, the functions of photosystem II (PSII) and photosystem I (PSI) were also impaired. Furthermore, the amount of core subunits of PSII and PSI, as well as PSII and PSI complexes reduced in yellow section of young leaves of dg169. Map-based positional cloning identified that phenotype of dg169 was attributed to a point mutation of ATase2 which converts the conserved Ile-155 residue to Asn. ATase2 catalyzes the first step of de novo purine biosynthesis. This mutation resulted in impaired purine synthesis and a significant decrease in ATP, ADP, GTP and GDP contents. The analysis of ATase2-GFP protein fusion showed that ATase2 was localized to nucleoid of chloroplasts. Our results further demonstrated that the levels of PEP-dependent transcripts in yellow section of young leaves of dg169 were decreased while NEP-dependent and both PEP- and NEP-dependent transcripts and chloroplast DNA replications were increased. The results in this study suggest that ATase2 plays an essential role in early chloroplast development through maintaining PEP function.

  13. Completion of the Chloroplast Genomes of Five Chinese Juglans and Their Contribution to Chloroplast Phylogeny.

    PubMed

    Hu, Yiheng; Woeste, Keith E; Zhao, Peng

    2016-01-01

    Juglans L. (walnuts and butternuts) is an economically and ecologically important genus in the family Juglandaceae. All Juglans are important nut and timber trees. Juglans regia (Common walnut), J. sigillata (Iron walnut), J. cathayensis (Chinese walnut), J. hopeiensis (Ma walnut), and J. mandshurica (Manchurian walnut) are native to or naturalized in China. A strongly supported phylogeny of these five species is not available due to a lack of informative molecular markers. We compared complete chloroplast genomes and determined the phylogenetic relationships among the five Chinese Juglans using IIumina sequencing. The plastid genomes ranged from 159,714 to 160,367 bp encoding 128 functional genes, including 88 protein-coding genes and 40 tRNA genes each. A complete map of the variability across the genomes of the five Juglans species was produced that included single nucleotide variants, indels (insertions and deletions), and large structural variants, as well as differences in simple sequence repeats (SSR) and repeat sequences. Molecular phylogeny strongly supported division of the five walnut species into two previously recognized sections (Juglans/Dioscaryon and Cardiocaryon) with a 100% bootstrap (BS) value using the complete cp genomes, protein coding sequences (CDS), and the introns and spacers (IGS) data. The availability of these genomes will provide genetic information for identifying species and hybrids, taxonomy, phylogeny, and evolution in Juglans, and also provide insight into utilization of Juglans plants.

  14. Completion of the Chloroplast Genomes of Five Chinese Juglans and Their Contribution to Chloroplast Phylogeny

    PubMed Central

    Hu, Yiheng; Woeste, Keith E.; Zhao, Peng

    2017-01-01

    Juglans L. (walnuts and butternuts) is an economically and ecologically important genus in the family Juglandaceae. All Juglans are important nut and timber trees. Juglans regia (Common walnut), J. sigillata (Iron walnut), J. cathayensis (Chinese walnut), J. hopeiensis (Ma walnut), and J. mandshurica (Manchurian walnut) are native to or naturalized in China. A strongly supported phylogeny of these five species is not available due to a lack of informative molecular markers. We compared complete chloroplast genomes and determined the phylogenetic relationships among the five Chinese Juglans using IIumina sequencing. The plastid genomes ranged from 159,714 to 160,367 bp encoding 128 functional genes, including 88 protein-coding genes and 40 tRNA genes each. A complete map of the variability across the genomes of the five Juglans species was produced that included single nucleotide variants, indels (insertions and deletions), and large structural variants, as well as differences in simple sequence repeats (SSR) and repeat sequences. Molecular phylogeny strongly supported division of the five walnut species into two previously recognized sections (Juglans/Dioscaryon and Cardiocaryon) with a 100% bootstrap (BS) value using the complete cp genomes, protein coding sequences (CDS), and the introns and spacers (IGS) data. The availability of these genomes will provide genetic information for identifying species and hybrids, taxonomy, phylogeny, and evolution in Juglans, and also provide insight into utilization of Juglans plants. PMID:28111577

  15. Effects and mechanism of acid rain on plant chloroplast ATP synthase.

    PubMed

    Sun, Jingwen; Hu, Huiqing; Li, Yueli; Wang, Lihong; Zhou, Qing; Huang, Xiaohua

    2016-09-01

    Acid rain can directly or indirectly affect plant physiological functions, especially photosynthesis. The enzyme ATP synthase is the key in photosynthetic energy conversion, and thus, it affects plant photosynthesis. To clarify the mechanism by which acid rain affects photosynthesis, we studied the effects of acid rain on plant growth, photosynthesis, chloroplast ATP synthase activity and gene expression, chloroplast ultrastructure, intracellular H(+) level, and water content of rice seedlings. Acid rain at pH 4.5 remained the chloroplast structure unchanged but increased the expression of six chloroplast ATP synthase subunits, promoted chloroplast ATP synthase activity, and increased photosynthesis and plant growth. Acid rain at pH 4.0 or less decreased leaf water content, destroyed chloroplast structure, inhibited the expression of six chloroplast ATP synthase subunits, decreased chloroplast ATP synthase activity, and reduced photosynthesis and plant growth. In conclusion, acid rain affected the chloroplast ultrastructure, chloroplast ATPase transcription and activity, and P n by changing the acidity in the cells, and thus influencing the plant growth and development. Finally, the effects of simulated acid rain on the test indices were found to be dose-dependent.

  16. Stochastic dynamics of actin filaments in guard cells regulating chloroplast localization during stomatal movement.

    PubMed

    Wang, Xiu-Ling; Gao, Xin-Qi; Wang, Xue-Chen

    2011-08-01

    Actin filaments and chloroplasts in guard cells play roles in stomatal function. However, detailed actin dynamics vary, and the roles that they play in chloroplast localization during stomatal movement remain to be determined. We examined the dynamics of actin filaments and chloroplast localization in transgenic tobacco expressing green fluorescent protein (GFP)-mouse talin in guard cells by time-lapse imaging. Actin filaments showed sliding, bundling and branching dynamics in moving guard cells. During stomatal movement, long filaments can be severed into small fragments, which can form longer filaments by end-joining activities. With chloroplast movement, actin filaments near chloroplasts showed severing and elongation activity in guard cells during stomatal movement. Cytochalasin B treatment abolished elongation, bundling and branching activities of actin filaments in guard cells, and these changes of actin filaments, and as a result, more chloroplasts were localized at the centre of guard cells. However, chloroplast turning to avoid high light, and sliding of actin fragments near the chloroplast, was unaffected following cytochalasin B treatment in guard cells. We suggest that the sliding dynamics of actin may play roles in chloroplast turning in guard cells. Our results indicate that the stochastic dynamics of actin filaments in guard cells regulate chloroplast localization during stomatal movement.

  17. Entire Photodamaged Chloroplasts Are Transported to the Central Vacuole by Autophagy[OPEN

    PubMed Central

    2017-01-01

    Turnover of dysfunctional organelles is vital to maintain homeostasis in eukaryotic cells. As photosynthetic organelles, plant chloroplasts can suffer sunlight-induced damage. However, the process for turnover of entire damaged chloroplasts remains unclear. Here, we demonstrate that autophagy is responsible for the elimination of sunlight-damaged, collapsed chloroplasts in Arabidopsis thaliana. We found that vacuolar transport of entire chloroplasts, termed chlorophagy, was induced by UV-B damage to the chloroplast apparatus. This transport did not occur in autophagy-defective atg mutants, which exhibited UV-B-sensitive phenotypes and accumulated collapsed chloroplasts. Use of a fluorescent protein marker of the autophagosomal membrane allowed us to image autophagosome-mediated transport of entire chloroplasts to the central vacuole. In contrast to sugar starvation, which preferentially induced distinct type of chloroplast-targeted autophagy that transports a part of stroma via the Rubisco-containing body (RCB) pathway, photooxidative damage induced chlorophagy without prior activation of RCB production. We further showed that chlorophagy is induced by chloroplast damage caused by either artificial visible light or natural sunlight. Thus, this report establishes that an autophagic process eliminates entire chloroplasts in response to light-induced damage. PMID:28123106

  18. Pb-Induced Avoidance-Like Chloroplast Movements in Fronds of Lemna trisulca L.

    PubMed Central

    Samardakiewicz, Sławomir; Krzeszowiec-Jeleń, Weronika; Bednarski, Waldemar; Jankowski, Artur; Suski, Szymon; Gabryś, Halina; Woźny, Adam

    2015-01-01

    Lead ions are particularly dangerous to the photosynthetic apparatus, but little is known about the effects of trace metals, including Pb, on regulation of chloroplast redistribution. In this study a new effect of lead on chloroplast distribution patterns and movements was demonstrated in mesophyll cells of a small-sized aquatic angiosperm Lemna trisulca L. (star duckweed). An analysis of confocal microscopy images of L. trisulca fronds treated with lead (15 μM Pb2+, 24 h) in darkness or in weak white light revealed an enhanced accumulation of chloroplasts in the profile position along the anticlinal cell walls, in comparison to untreated plants. The rearrangement of chloroplasts in their response to lead ions in darkness was similar to the avoidance response of chloroplasts in plants treated with strong white light. Transmission electron microscopy X-ray microanalysis showed that intracellular chloroplast arrangement was independent of the location of Pb deposits, suggesting that lead causes redistribution of chloroplasts, which looks like a light-induced avoidance response, but is not a real avoidance response to the metal. Furthermore, a similar redistribution of chloroplasts in L. trisulca cells in darkness was observed also under the influence of exogenously applied hydrogen peroxide (H2O2). In addition, we detected an enhanced accumulation of endogenous H2O2 after treatment of plants with lead. Interestingly, H2O2-specific scavenger catalase partly abolished the Pb-induced chloroplast response. These results suggest that H2O2 can be involved in the avoidance-like movement of chloroplasts induced by lead. Analysis of photometric measurements revealed also strong inhibition (but not complete) of blue-light-induced chloroplast movements by lead. This inhibition may result from disturbances in the actin cytoskeleton, as we observed fragmentation and disappearance of actin filaments around chloroplasts. Results of this study show that the mechanisms of the toxic

  19. Pb-induced avoidance-like chloroplast movements in fronds of Lemna trisulca L.

    PubMed

    Samardakiewicz, Sławomir; Krzeszowiec-Jeleń, Weronika; Bednarski, Waldemar; Jankowski, Artur; Suski, Szymon; Gabryś, Halina; Woźny, Adam

    2015-01-01

    Lead ions are particularly dangerous to the photosynthetic apparatus, but little is known about the effects of trace metals, including Pb, on regulation of chloroplast redistribution. In this study a new effect of lead on chloroplast distribution patterns and movements was demonstrated in mesophyll cells of a small-sized aquatic angiosperm Lemna trisulca L. (star duckweed). An analysis of confocal microscopy images of L. trisulca fronds treated with lead (15 μM Pb2+, 24 h) in darkness or in weak white light revealed an enhanced accumulation of chloroplasts in the profile position along the anticlinal cell walls, in comparison to untreated plants. The rearrangement of chloroplasts in their response to lead ions in darkness was similar to the avoidance response of chloroplasts in plants treated with strong white light. Transmission electron microscopy X-ray microanalysis showed that intracellular chloroplast arrangement was independent of the location of Pb deposits, suggesting that lead causes redistribution of chloroplasts, which looks like a light-induced avoidance response, but is not a real avoidance response to the metal. Furthermore, a similar redistribution of chloroplasts in L. trisulca cells in darkness was observed also under the influence of exogenously applied hydrogen peroxide (H2O2). In addition, we detected an enhanced accumulation of endogenous H2O2 after treatment of plants with lead. Interestingly, H2O2-specific scavenger catalase partly abolished the Pb-induced chloroplast response. These results suggest that H2O2 can be involved in the avoidance-like movement of chloroplasts induced by lead. Analysis of photometric measurements revealed also strong inhibition (but not complete) of blue-light-induced chloroplast movements by lead. This inhibition may result from disturbances in the actin cytoskeleton, as we observed fragmentation and disappearance of actin filaments around chloroplasts. Results of this study show that the mechanisms of the toxic

  20. Myrionecta Rubra Population Genetic Diversity and Its Cryptophyte Chloroplast Specificity in Recurrent Red Tides in the Columbia River Estuary

    SciTech Connect

    Herfort, Lydie; Peterson, Tawnya D.; McCue, Lee Ann; Crump, Byron C.; Prahl, Fredrick G.; Baptista, Antonio M.; Campbell, Victoria; Warnick, Rachel; Selby, Mikaela; Roegner, G. Curtis; Zuber, Peter A.

    2011-01-04

    For at least a decade, annually recurring blooms of the photosynthetic ciliate, Myrionecta rubra have been observed in the Columbia River estuary in late summer. In an effort to understand the dynamics of these blooms, we investigated the genetic variability of M. rubra and its cryptophyte plastids within three large estuarine blooms formed in consecutive years (2007-2009), and conducted a broader spatial survey along the coasts of Oregon/Washington. Analysis of the ‘18S-28S’ sequences specific for Mesodiniidae uncovered at least 7 variants of M. rubra within the Columbia River coastal margin in spring and summer, but only one of these M. rubra variants was implicated in estuary bloom formation. Using a multigene approach, we show that the bloom-forming variant of M. rubra appears to harbor the same cryptophyte chloroplast in recurring blooms. Analyses of chloroplast 16S rRNA, cryptophyte RuBisCO and Photosystem II D2 genes together suggest that the plastid is derived from Teleaulax amphioxeia. Free-living cells of this species and of other cryptophytes were practically absent from the bloom patches in the estuary main channels based on 18S rDNA sequence analyses. The respectively low and high proportions of T. amphioxeia nuclei and chloroplasts signals found in the M. rubra bloom of the Columbia River estuary in successive years supports the notion of a transient association between T. amphioxeia and the bloom-forming M. rubra variant, with loss of cryptophyte nuclei. The genetic variability of M. rubra uncovered here is relevant to the controversy in the literature regarding the cryptophyte /M. rubra association.

  1. Chloroplast Dynamics and Photosynthetic Efficiency: Final Technical Report

    SciTech Connect

    Hanson, Maureen

    2016-11-03

    This project investigated the mechanism by which chloroplasts position themselves to maximize solar energy utilization, to enhance gas exchange, to minimize environmental stress, and to promote efficient exchange of metabolites with other compartments within the plant cell. Chloroplasts move within leaf cells to optimize light levels, moving toward levels of light useful for photosynthesis while moving away from excess light. Plastids sometimes extend their reach by sending out projections (stromules) that can connect anchor chloroplasts in position within the cell or provide close contacts with plasma membrane, mitochondria, peroxisomes, endoplasmic reticulum, and the nucleus. The intracellular location of chloroplasts in relation to other organelles with which they share biosynthetic pathways, such as peroxisomes and mitochondria in photorespiration, affects metabolite flow. This work contributed to the knowledge of the mechanisms of organelle movement and anchoring in specific locations in plant cells and how proteins traffic within the cell. We identified two domains on 12 of the 13 Arabidopsis myosins that were similar to the vacuole-binding (V) domain characterized in yeast and to the DIL domain characterized in yeast and mouse as required for secretory vesicle or melanosome movement, respectively. Because all of the Arabidopsis regions with homology to the V domain contain the amino acid sequence PAL, we refer to this region as the Arabidopsis PAL domain. We have used the yeast Myo2p tail structural information to model the 12 myosin XI tail domains containing the homologous PAL and DIL domains. Eight YFP::DIL domain fusions labeled peroxisomes; none labeled mitochondria or chloroplasts. Six myosin XI Vacuole domains labeled mitochondria and seven labeled Golgi bodies. The Arabidopsis myosin XI-F PAL domain and the homologous myosin XI-F PAL domain from N. benthamiana labels chloroplasts and stromules in N. benthamiana leaves. Using an Arabidopsis line

  2. Phosphorylation of the transit sequence of chloroplast precursor proteins.

    PubMed

    Waegemann, K; Soll, J

    1996-03-15

    A protein kinase was located in the cytosol of pea mesophyll cells. The protein kinase phosphorylates, in an ATP-dependent manner, chloroplast-destined precursor proteins but not precursor proteins, which are located to plant mitochondria or plant peroxisomes. The phosphorylation occurs on either serine or threonine residues, depending on the precursor protein used. We demonstrate the specific phosphorylation of the precursor forms of the chloroplast stroma proteins ferredoxin (preFd), small subunit of ribulose-bisphosphate-carboxylase (preSSU), the thylakoid localized light-harvesting chlorophyll a/b-binding protein (preLHCP), and the thylakoid lumen-localized proteins of the oxygen-evolving complex of 23 kDa (preOE23) and 33 kDa (preOE33). In the case of thylakoid lumen proteins which possess bipartite transit sequences, the phosphorylation occurs within the stroma-targeting domain. By using single amino acid substitution within the presequences of preSSU, preOE23, and preOE33, we were able to tentatively identify a consensus motif for the precursor protein protein kinase. This motif is (P/G)X(n)(R/K)X(n)(S/T)X(n) (S*/T*), were n = 0-3 amino acids spacer and S*/T* represents the phosphate acceptor. The precursor protein protein kinase is present only in plant extracts, e.g. wheat germ and pea, but not in a reticulocyte lysate. Protein import experiments into chloroplasts revealed that phosphorylated preSSU binds to the organelles, but dephosphorylation seems required to complete the translocation process and to obtain complete import. These results suggest that a precursor protein protein phosphatase is involved in chloroplast import and represents a so far unidentified component of the import machinery. In contrast to sucrose synthase, a cytosolic marker protein, the precursor protein protein kinase seems to adhere partially to the chloroplast surface. A phosphorylation-dephosphorylation cycle of chloroplast-destined precursor proteins might represent one step

  3. Chloroplast-targeted bacterial RecA proteins confer tolerance to chloroplast DNA damage by methyl viologen or UV-C radiation in tobacco (Nicotiana tabacum) plants.

    PubMed

    Jeon, Hyesung; Jin, Yong-Mei; Choi, Mi Hwa; Lee, Hyeyun; Kim, Minkyun

    2013-02-01

    The nature and importance of the DNA repair system in the chloroplasts of higher plants under oxidative stress or UV radiation-induced genotoxicity was investigated via gain-of-functional approaches exploiting bacterial RecAs. For this purpose, transgenic tobacco (Nicotiana tabacum) plants and cell suspensions overexpressing Escherichia coli or Pseudomonas aeruginosa RecA fused to a chloroplast-targeting transit peptide were first produced. The transgenic tobacco plants maintained higher amounts of chloroplast DNA compared with wild-type (WT) upon treatments with methyl viologen (MV), a herbicide that generates reactive oxygen species (ROS) in chloroplasts. Consistent with these results, the transgenic tobacco leaves showed less bleaching than WT following MV exposure. Similarly, the MV-treated transgenic Arabidopsis plants overexpressing the chloroplast RecA homologue RECA1 showed weak bleaching, while the recA1 mutant showed opposite results upon MV treatment. In addition, when exposed to UV-C radiation, the dark-grown E. coli RecA-overexpressing transgenic tobacco cell suspensions, but not their WT counterparts, resumed growth and greening after the recovery period under light conditions. Measurements of UV radiation-induced chloroplast DNA damage using DraI assays (Harlow et al. 1994) with the chloroplast rbcL DNA probe and quantitative PCR analyses showed that the transgenic cell suspensions better repaired their UV-C radiation-induced chloroplast DNA lesions compared with WT. Taken all together, it was concluded that RecA-overexpressing transgenic plants are endowed with an increased chloroplast DNA maintenance capacity and enhanced repair activities, and consequently have a higher survival tolerance to genotoxic stresses. These observations are made possible by the functional compatibility of the bacterial RecAs in chloroplasts. Copyright © Physiologia Plantarum 2012.

  4. Changes in chloroplast lipid contents and chloroplast ultrastructure in Sulla carnosa and Sulla coronaria leaves under salt stress.

    PubMed

    Bejaoui, Fatma; Salas, Joaquín J; Nouairi, Issam; Smaoui, Abderrazak; Abdelly, Chedly; Martínez-Force, Enrique; Youssef, Nabil Ben

    2016-07-01

    The possible involvement of chloroplast lipids in the mechanisms of NaCl tolerance was studied in leaves of two varieties of Fabaceae: Sulla carnosa and Sulla coronaria, which were subjected to 200mM NaCl over 20days. Changes in membrane lipid peroxidation, chloroplast lipids content, fatty acids (FA) composition and the ultrastructure of chloroplasts under salt stress were investigated. Chloroplast lipids were separated and quantified by high performance liquid chromatography coupled to evaporative light scattering detection (HPLC/ELSD). The results showed that salinity induced a significant decrease in digalactosyldiacylglycerol (DGDG), phosphatidylglycerol (PG) and sulfoquinovosylglycerol (SQDG) content in both S. carnosa and S. coronaria leaves, whereas monogalactosyldiacylglycerol (MGDG) content did not change significantly in S. carnosa leaves. The MGDG/DGDG ratio remained stable in S. coronaria leaves but increased in those of S. carnosa. In addition, the unsaturated-to-saturated fatty acids ratio (UFAs:SFAs) did not change under salt stress in S. coronaria leaves, while it decreased significantly in S. carnosa leaves. Moreover, salinity did not induce significant changes in MGDG and DGDG unsaturation level in S. carnosa leaves, in contrast to S. coronaria, in which salinity seems to enhance the unsaturation level in MGDG, DGDG and PG. Furthermore, the level of membrane lipid peroxidation, as expressed by malondialdehyde (MDA) levels, increased at 200mM in S. carnosa leaves, while it did not change significantly in those of S. coronaria. With respect to the ultrastructure of chloroplasts at 200mM NaCl, investigated by transmission electron microscopy (TEM), salt-stress caused the swelling of thylakoids in S. carnosa mesophyll. These ultrastructural changes were observed especially in the spongy tissue in S. coronaria. Taken together, these findings suggest that the stability of MGDG/DGDG ratio, the unchanged unsaturation level, and increasing unsaturation

  5. Polyphyletism of Celastrales deduced from a chloroplast noncoding DNA region.

    PubMed

    Savolainen, V; Spichiger, R; Manen, J F

    1997-04-01

    In a previous study we examined the phylogeny of four families related to the angiosperm order Celastrales based on chloroplast rbcL 5' flanking sequences. We have added here several additional dicots, sampled from 6 of the 7 families of Celastrales sensu Cronquist and 19 putatively related genera. Based on a cladistic analysis of these DNA sequences, the order Celastrales appears polyphyletic: it is here restricted to Celastraceae (including Hippocrateaceae and Brexia) with Parnassia as sister; Aquifoliaceae plus Helwingia are included in Asteridae. Neither Salvadoraceae nor Geissolomataceae, Icacinaceae, Phellinaceae, Aextoxicaceae, Corynocarpaceae, Dichapetalaceae, Stackhousiaceae, or Goupiaceae are related to Celastrales. The usefulness of this noncoding region is discussed and the influence of the A + T content of neighboring bases on the increase of transversions is also observed as previously shown in chloroplast noncoding regions of monocots.

  6. The complete chloroplast genome sequence of Safflower (Carthamus tinctorius L.).

    PubMed

    Lu, Chaolong; Shen, Qi; Yang, Jun; Wang, Bo; Song, Chi

    2016-09-01

    Safflower (Carthamus tinctorius L.) is a traditional medical plants of Asia. In this study, the complete chloroplast genome of safflower was presented. The total genome size was 153,675 bp in length, containing a pair of inverted repeats (IRs) of 25,407 bp, separated by large single copy (LSC) and small single copy (SSC) of 83,606 bp and 19,156 bp, respectively. Overall GC content of the genome was 37.4%. The chloroplast genome harbored 127 annotated genes, including 89 protein coding genes, 30 tRNA genes and 8 rRNA genes. A total of 7 of these genes were duplicated in the inverted repeat regions. Twelve genes contained one intron.

  7. Chloroplast microsatellite markers for Artocarpus (Moraceae) developed from transcriptome sequences.

    PubMed

    Gardner, Elliot M; Laricchia, Kristen M; Murphy, Matthew; Ragone, Diane; Scheffler, Brian E; Simpson, Sheron; Williams, Evelyn W; Zerega, Nyree J C

    2015-09-01

    Chloroplast microsatellite loci were characterized from transcriptomes of Artocarpus altilis (breadfruit) and A. camansi (breadnut). They were tested in A. odoratissimus (terap) and A. altilis and evaluated in silico for two congeners. Fifteen simple sequence repeats (SSRs) were identified in chloroplast sequences from four Artocarpus transcriptome assemblies. The markers were evaluated using capillary electrophoresis in A. odoratissimus (105 accessions) and A. altilis (73). They were also evaluated in silico in A. altilis (10), A. camansi (6), and A. altilis × A. mariannensis (7) transcriptomes. All loci were polymorphic in at least one species, with all 15 polymorphic in A. camansi. Per species, average alleles per locus ranged between 2.2 and 2.5. Three loci had evidence of fragment-length homoplasy. These markers will complement existing nuclear markers by enabling confident identification of maternal and clone lines, which are often important in vegetatively propagated crops such as breadfruit.

  8. Chloroplast and nuclear microsatellite analysis of Aegilops cylindrica.

    PubMed

    Gandhi, Harish T; Vales, M Isabel; Watson, Christy J W; Mallory-Smith, Carol A; Mori, Naoki; Rehman, Maqsood; Zemetra, Robert S; Riera-Lizarazu, Oscar

    2005-08-01

    Aegilops cylindrica Host (2n = 4x = 28, genome CCDD) is an allotetraploid formed by hybridization between the diploid species Ae. tauschii Coss. (2n = 2x = 14, genome DD) and Ae. markgrafii (Greuter) Hammer (2n = 2x = 14, genome CC). Previous research has shown that Ae. tauschii contributed its cytoplasm to Ae. cylindrica. However, our analysis with chloroplast microsatellite markers showed that 1 of the 36 Ae. cylindrica accessions studied, TK 116 (PI 486249), had a plastome derived from Ae. markgrafii rather than Ae. tauschii. Thus, Ae. markgrafii has also contributed its cytoplasm to Ae. cylindrica. Our analysis of chloroplast and nuclear microsatellite markers also suggests that D-type plastome and the D genome in Ae. cylindrica were closely related to, and were probably derived from, the tauschii gene pool of Ae. tauschii. A determination of the likely source of the C genome and the C-type plastome in Ae. cylindrica was not possible.

  9. The whole chloroplast genome of shrub willows (Salix suchowensis).

    PubMed

    Wu, Zhiqiang

    2016-05-01

    The whole chloroplast genome of Salix suchowensis was determined in this study using next generation sequencing data. The total genome size was 155,214 bp in length, containing a pair of inverted repeats (IRs) of 27,459 bp, which were separated by large single copy (LSC) and small single copy (SSC) of 84,077 bp and 16,219 bp, respectively. The overall GC contents of the chloroplast genome were 36.73%. One hundred and ten unique genes were annotated, including 76 protein coding genes, 30 tRNA genes and 4 rRNA genes. Among these, 18 are duplicated in the inverted repeat regions, 14 genes contained 1 intron, and 3 genes (rps12, clpP and ycf3) comprised of 2 introns.

  10. Ferrous Ion Transport across Chloroplast Inner Envelope Membranes1

    PubMed Central

    Shingles, Richard; North, Marisa; McCarty, Richard E.

    2002-01-01

    The initial rate of Fe2+ movement across the inner envelope membrane of pea (Pisum sativum) chloroplasts was directly measured by stopped-flow spectrofluorometry using membrane vesicles loaded with the Fe2+-sensitive fluorophore, Phen Green SK. The rate of Fe2+ transport was rapid, coming to equilibrium within 3s. The maximal rate and concentration dependence of Fe2+ transport in predominantly right-side-out vesicles were nearly equivalent to those measured in largely inside-out vesicles. Fe2+ transport was stimulated by an inwardly directed electrochemical proton gradient across right-side-out vesicles, an effect that was diminished by the addition of valinomycin in the presence of K+. Fe2+ transport was inhibited by Zn2+, in a competitive manner, as well as by Cu2+ and Mn2+. These results indicate that inward-directed Fe2+ transport across the chloroplast inner envelope occurs by a potential-stimulated uniport mechanism. PMID:11891257

  11. Toxic effects of copper on photosystem II of spinach chloroplasts

    SciTech Connect

    Hsu, Bandar; Lee, Jeeyau )

    1988-05-01

    The room temperature fluorescence induction of chloroplasts was utilized as a probe to locate the site of inhibition on PSII by copper. It was found that, while the initial fluorescence yield was hardly affected, the variable fluorescence yield was lowered without significant change in its kinetics. Addition of DCMU, or abolishing oxygen evolution capability by Tris treatment, did not alter this basic inhibition pattern. Copper was also found to lower the fluorescence yield of chloroplasts treated with linolenic acid which inhibited the secondary electron transport on both oxidizing and reducing sides of PSII. The data indicate that copper adversely affects the primary change separation at the PSII reaction center. We suggest that the inhibition is due to creation of a lesion close to the reaction center, leading to increased dissipation of incoming excitation energy to heat.

  12. Structural Basis for Redox Regulation of Cytoplasmic and Chloroplastic Triosephosphate Isomerases from Arabidopsis thaliana

    PubMed Central

    López-Castillo, Laura M.; Jiménez-Sandoval, Pedro; Baruch-Torres, Noe; Trasviña-Arenas, Carlos H.; Díaz-Quezada, Corina; Lara-González, Samuel; Winkler, Robert; Brieba, Luis G.

    2016-01-01

    In plants triosephosphate isomerase (TPI) interconverts glyceraldehyde 3-phosphate (G3P) and dihydroxyacetone phosphate (DHAP) during glycolysis, gluconeogenesis, and the Calvin-Benson cycle. The nuclear genome of land plants encodes two tpi genes, one gene product is located in the cytoplasm and the other is imported into the chloroplast. Herein we report the crystal structures of the TPIs from the vascular plant Arabidopsis thaliana (AtTPIs) and address their enzymatic modulation by redox agents. Cytoplasmic TPI (cTPI) and chloroplast TPI (pdTPI) share more than 60% amino acid identity and assemble as (β-α)8 dimers with high structural homology. cTPI and pdTPI harbor two and one accessible thiol groups per monomer respectively. cTPI and pdTPI present a cysteine at an equivalent structural position (C13 and C15 respectively) and cTPI also contains a specific solvent accessible cysteine at residue 218 (cTPI-C218). Site directed mutagenesis of residues pdTPI-C15, cTPI-C13, and cTPI-C218 to serine substantially decreases enzymatic activity, indicating that the structural integrity of these cysteines is necessary for catalysis. AtTPIs exhibit differential responses to oxidative agents, cTPI is susceptible to oxidative agents such as diamide and H2O2, whereas pdTPI is resistant to inhibition. Incubation of AtTPIs with the sulfhydryl conjugating reagents methylmethane thiosulfonate (MMTS) and glutathione inhibits enzymatic activity. However, the concentration necessary to inhibit pdTPI is at least two orders of magnitude higher than the concentration needed to inhibit cTPI. Western-blot analysis indicates that residues cTPI-C13, cTPI-C218, and pdTPI-C15 conjugate with glutathione. In summary, our data indicate that AtTPIs could be redox regulated by the derivatization of specific AtTPI cysteines (cTPI-C13 and pdTPI-C15 and cTPI-C218). Since AtTPIs have evolved by gene duplication, the higher resistance of pdTPI to redox agents may be an adaptive consequence to the

  13. A Viroid RNA with a Specific Structural Motif Inhibits Chloroplast Development[W

    PubMed Central

    Rodio, Maria-Elena; Delgado, Sonia; De Stradis, Angelo; Gómez, María-Dolores; Flores, Ricardo; Di Serio, Francesco

    2007-01-01

    Peach latent mosaic viroid (PLMVd) is a chloroplast-replicating RNA that propagates in its natural host, peach (Prunus persica), as a complex mixture of variants, some of which are endowed with specific structural and pathogenic properties. This is the case of variant PC-C40, with an insertion of 12 to 13 nucleotides that folds into a hairpin capped by a U-rich loop, which is responsible for an albino-variegated phenotype known as peach calico (PC). We have applied a combination of ultrastructural, biochemical, and molecular approaches to dissect the pathogenic effects of PC-C40. Albino sectors of leaves infected with variant PC-C40 presented palisade cells that did not completely differentiate into a columnar layer and altered plastids with irregular shape and size and with rudimentary thylakoids, resembling proplastids. Furthermore, impaired processing and accumulation of plastid rRNAs and, consequently, of the plastid translation machinery was observed in the albino sectors of leaves infected with variant PC-C40 but not in the adjacent green areas or in leaves infected by mosaic-inducing or latent variants (including PC-C40Δ, in which the 12- to 13-nucleotide insertion was deleted). Protein gel blot and RT-PCR analyses showed that the altered plastids support the import of nucleus-encoded proteins, including a chloroplast RNA polymerase, the transcripts of which were detected. RNA gel blot and in situ hybridizations revealed that PLMVd replicates in the albino leaf sectors and that it can invade the shoot apical meristem and induce alterations in proplastids, bypassing the RNA surveillance system that restricts the entry of a nucleus-replicating viroid and most RNA viruses. Therefore, a non-protein-coding RNA with a specific structural motif can interfere with an early step of the chloroplast developmental program, leading ultimately to an albino-variegated phenotype resembling that of certain variegated mutants in which plastid rRNA maturation is also impaired

  14. Chloroplast Structure and Function Is Altered in the NCS2 Maize Mitochondrial Mutant 1

    PubMed Central

    Roussell, Deborah L.; Thompson, Deborah L.; Pallardy, Steve G.; Miles, Donald; Newton, Kathleen J.

    1991-01-01

    The nonchromosomal stripe 2 (NCS2) mutant of maize (Zea mays L.) has a DNA rearrangement in the mitochondrial genome that segregates with the abnormal growth phenotype. Yet, the NCS2 characteristic phenotype includes striped sectors of pale-green tissue on the leaves. This suggests a chloroplast abnormality. To characterize the chloroplasts present in the mutant sectors, we examined the chloroplast structure by electron microscopy, chloroplast function by radiolabeled carbon dioxide fixation and fluorescence induction kinetics, and thylakoid protein composition by polyacrylamide gel electrophoresis. The data from these analyses suggest abnormal or prematurely arrested chloroplast development. Deleterious effects of the NCS2 mutant mitochondria upon the cells of the leaf include structural and functional alterations in the both the bundle sheath and mesophyll chloroplasts. ImagesFigure 1Figure 2Figure 3Figure 5Figure 6 PMID:16668157

  15. Photoprotective function of chloroplast avoidance movement: in vivo chlorophyll fluorescence study.

    PubMed

    Sztatelman, Olga; Waloszek, Andrzej; Banaś, Agnieszka Katarzyna; Gabryś, Halina

    2010-06-15

    Light-induced chloroplast avoidance movement has long been considered to be a photoprotective mechanism. Here, we present an experimental model in which this function can be shown for wild type Arabidopsis thaliana. We used blue light of different fluence rates for chloroplast positioning, and strong red light inactive in chlorop