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1.
Methods Mol Biol ; 2288: 145-162, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34270010

RESUMO

Culture of isolated microspores is a widely used method to obtain haploid and doubled haploid plants for many crop species. This protocol describes the steps necessary to obtain a large number of microspore derived embryos for pakchoi (Brassica rapa L. ssp. chinensis) and zicaitai (Brassica rapa L. ssp. сhinensis Hanelt var. purpuraria Kitam).


Assuntos
Brassica rapa/crescimento & desenvolvimento , Brassica rapa/genética , Melhoramento Vegetal/métodos , Brassica rapa/ultraestrutura , Cloroplastos/ultraestrutura , Cromossomos de Plantas/ultraestrutura , Produtos Agrícolas/genética , Produtos Agrícolas/crescimento & desenvolvimento , Meios de Cultura/química , Diploide , Germinação/genética , Haploidia , Homozigoto , Microscopia de Fluorescência , Biologia Molecular/métodos , Ploidias , Pólen/genética , Pólen/crescimento & desenvolvimento , Técnicas de Cultura de Tecidos
2.
Plant Mol Biol ; 106(6): 521-531, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34224063

RESUMO

KEY MESSAGE: We characterize a functional lincRNA, XH123 in cotton seedling in defense of cold stress. The silencing of XH123 leads to increased sensitivity to cold stress and the decay of chloroplast. Cotton, which originated from the arid mid-American region, is one of the most important cash crops worldwide. Cultivated cotton is now widely spread throughout high-altitude regions such as those in the far northwest of Asia. In such areas, spring temperatures below 12 ℃ impose cold stress on cotton seedlings, with concomitant threat of lost yield and productivity. It is documented that cold stress can induce differential expression of long noncoding RNAs (lncRNAs) in cotton; however, it is not yet clear if these cold-responsive lncRNAs are actively involved with tolerance of cold stress at the molecular level. Here, we select ten long intergenic non-coding RNAs as candidate genes and use virus-induced gene silencing and additional cold treatments to examine their roles in the response to cold stress during the cotton seedling stage. One such gene, XH123, was revealed to be involved in tolerance of cold stress. Specifically, XH123-silenced plants demonstrated sensitivity to cold stress, exhibiting chloroplast damage and increased endogenous levels of reactive oxygen species. The transcriptome profile of XH123-silenced seedlings was similar to that of cold-stressed seedlings having the known cold stress gene PIF3 silenced. These results imply that the lincRNA XH123 is actively involved with cold stress regulation in cotton during the seedling stage.


Assuntos
Resposta ao Choque Frio/genética , Perfilação da Expressão Gênica/métodos , Regulação da Expressão Gênica de Plantas , Gossypium/genética , RNA Longo não Codificante/genética , RNA de Plantas/genética , Adaptação Fisiológica/genética , Cloroplastos/genética , Cloroplastos/metabolismo , Cloroplastos/ultraestrutura , Temperatura Baixa , Inativação Gênica , Gossypium/crescimento & desenvolvimento , Microscopia Eletrônica de Transmissão , Folhas de Planta/genética , Folhas de Planta/metabolismo , Folhas de Planta/ultraestrutura , RNA-Seq/métodos , Plântula/genética , Plântula/crescimento & desenvolvimento
3.
Int J Mol Sci ; 22(14)2021 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-34299279

RESUMO

Modern light microscopy imaging techniques have substantially advanced our knowledge about the ultrastructure of plant cells and their organelles. Laser-scanning microscopy and digital light microscopy imaging techniques, in general-in addition to their high sensitivity, fast data acquisition, and great versatility of 2D-4D image analyses-also opened the technical possibilities to combine microscopy imaging with spectroscopic measurements. In this review, we focus our attention on differential polarization (DP) imaging techniques and on their applications on plant cell walls and chloroplasts, and show how these techniques provided unique and quantitative information on the anisotropic molecular organization of plant cell constituents: (i) We briefly describe how laser-scanning microscopes (LSMs) and the enhanced-resolution Re-scan Confocal Microscope (RCM of Confocal.nl Ltd. Amsterdam, Netherlands) can be equipped with DP attachments-making them capable of measuring different polarization spectroscopy parameters, parallel with the 'conventional' intensity imaging. (ii) We show examples of different faces of the strong anisotropic molecular organization of chloroplast thylakoid membranes. (iii) We illustrate the use of DP imaging of cell walls from a variety of wood samples and demonstrate the use of quantitative analysis. (iv) Finally, we outline the perspectives of further technical developments of micro-spectropolarimetry imaging and its use in plant cell studies.


Assuntos
Células Vegetais/ultraestrutura , Anisotropia , Parede Celular/ultraestrutura , Cloroplastos/ultraestrutura , Microscopia Confocal/métodos , Microscopia de Polarização/métodos , Tilacoides/ultraestrutura
4.
Int J Mol Sci ; 22(9)2021 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-34063012

RESUMO

Single-walled carbon nanotubes (SWCNTs) emerge as promising novel carbon-based nanoparticles for use in biomedicine, pharmacology and precision agriculture. They were shown to penetrate cell walls and membranes and to physically interact and exchange electrons with photosynthetic complexes in vitro. Here, for the first time, we studied the concentration-dependent effect of foliar application of copolymer-grafted SWCNTs on the structural and functional characteristics of intact pea plants. The lowest used concentration of 10 mg L-1 did not cause any harmful effects on the studied leaf characteristics, while abundant epicuticular wax generation on both leaf surfaces was observed after 300 mg L-1 treatment. Swelling of both the granal and the stromal regions of thylakoid membranes was detected after application of 100 mg L-1 and was most pronounced after 300 mg L-1. Higher SWCNT doses lead to impaired photosynthesis in terms of lower proton motive force generation, slower generation of non-photochemical quenching and reduced zeaxanthin content; however, the photosystem II function was largely preserved. Our results clearly indicate that SWCNTs affect the photosynthetic apparatus in a concentration-dependent manner. Low doses (10 mg L-1) of SWCNTs appear to be a safe suitable object for future development of nanocarriers for substances that are beneficial for plant growth.


Assuntos
Cloroplastos/ultraestrutura , Nanotubos de Carbono/química , Ervilhas/fisiologia , Ervilhas/ultraestrutura , Fotossíntese , Folhas de Planta/anatomia & histologia , Dióxido de Carbono/metabolismo , Carotenoides/metabolismo , Permeabilidade da Membrana Celular , Clorofila/metabolismo , Fluorescência , Nanotubos de Carbono/ultraestrutura , Complexo de Proteína do Fotossistema II/metabolismo , Folhas de Planta/ultraestrutura , Prótons , Tilacoides/metabolismo , Fatores de Tempo , Xantofilas/metabolismo
5.
Nat Plants ; 7(4): 514-523, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33875833

RESUMO

Etioplasts are photosynthetically inactive plastids that accumulate when light levels are too low for chloroplast maturation. The etioplast inner membrane consists of a paracrystalline tubular lattice and peripheral, disk-shaped membranes, respectively known as the prolamellar body and prothylakoids. These distinct membrane regions are connected into one continuous compartment. To date, no structures of protein complexes in or at etioplast membranes have been reported. Here, we used electron cryo-tomography to explore the molecular membrane landscape of pea and maize etioplasts. Our tomographic reconstructions show that ATP synthase monomers are enriched in the prothylakoids, and plastid ribosomes in the tubular lattice. The entire tubular lattice is covered by regular helical arrays of a membrane-associated protein, which we identified as the 37-kDa enzyme, light-dependent protochlorophyllide oxidoreductase (LPOR). LPOR is the most abundant protein in the etioplast, where it is responsible for chlorophyll biosynthesis, photoprotection and defining the membrane geometry of the prolamellar body. Based on the 9-Å-resolution volume of the subtomogram average, we propose a structural model of membrane-associated LPOR.


Assuntos
Cloroplastos/ultraestrutura , Membranas Intracelulares/ultraestrutura , Ervilhas/ultraestrutura , Zea mays/ultraestrutura , Tomografia com Microscopia Eletrônica
6.
BMC Plant Biol ; 21(1): 134, 2021 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-33711931

RESUMO

BACKGROUND: Providing the photosynthesis factory for plants, chloroplasts are critical for crop biomass and economic yield. However, chloroplast development is a complicated process, coordinated by the cross-communication between the nucleus and plastids, and the underlying biogenesis mechanism has not been fully revealed. Variegation mutants have provided ideal models to identify genes or factors involved in chloroplast development. Well-developed chloroplasts are present in the green tissue areas, while the white areas contain undifferentiated plastids that are deficient in chlorophyll. Unlike albino plants, variegation mutants survive to maturity and enable investigation into the signaling pathways underlying chloroplast biogenesis. The allelic variegated mutants in barley, grandpa 1 (gpa1), have long been identified but have not been genetically characterized. RESULTS: We characterized and genetically analyzed the grandpa1.a (gpa1.a) mutant. The chloroplast ultrastructure was evaluated using transmission electron microscopy (TEM), and it was confirmed that chloroplast biogenesis was disrupted in the white sections of gpa1.a. To determine the precise position of Gpa1, a high-resolution genetic map was constructed. Segregating individuals were genotyped with the barley 50 k iSelect SNP Array, and the linked SNPs were converted to PCR-based markers for genetic mapping. The Gpa1 gene was mapped to chromosome 2H within a gene cluster functionally related to photosynthesis or chloroplast differentiation. In the variegated gpa1.a mutant, we identified a large deletion in this gene cluster that eliminates a putative plastid terminal oxidase (PTOX). CONCLUSIONS: Here we characterized and genetically mapped the gpa1.a mutation causing a variegation phenotype in barley. The PTOX-encoding gene in the delimited region is a promising candidate for Gpa1. Therefore, the present study provides a foundation for the cloning of Gpa1, which will elevate our understanding of the molecular mechanisms underlying chloroplast biogenesis, particularly in monocot plants.


Assuntos
Cloroplastos/genética , Cloroplastos/ultraestrutura , Cor , Hordeum/genética , Folhas de Planta/anatomia & histologia , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/genética , Mapeamento Cromossômico , Produtos Agrícolas/genética , Produtos Agrícolas/crescimento & desenvolvimento , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Variação Genética , Hordeum/crescimento & desenvolvimento , Mutação , Fenótipo
7.
Plant Mol Biol ; 105(6): 637-654, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33543390

RESUMO

KEY MESSAGE: We demonstrate that OsNAC109 regulates senescence, growth and development via binding to the cis-element CNTCSSNNSCAVG and altering the expression of multiple senescence- and hormone-associated genes in rice. The NAC family is one of the largest transcripton factor families in plants and plays an essential role in plant development, leaf senescence and responses to biotic/abiotic stresses through modulating the expression of numerous genes. Here, we isolated and characterized a novel yellow leaf 3 (yl3) mutant exhibiting arrested-growth, increased accumulation of reactive oxygen species (ROS), decreased level of soluble proteins, increased level of malondialdehyde (MDA), reduced activities of ROS scavenging enzymes, altered expression of photosynthesis and senescence/hormone-associated genes. The yellow leaf and arrested-growth trait was controlled by a single recessive gene located to chromosome 9. A single nucleotide substitution was detected in the mutant allele leading to premature termination of its coding protein. Genetic complementation could rescue the mutant phenotype while the YL3 knockout lines displayed similar phenotype to WT. YL3 was expressed in all tissues tested and predicted to encode a transcriptional factor OsNAC109 which localizes to the nucleus. It was confirmed that OsNAC109 could directly regulate the expression of OsNAP, OsNYC3, OsEATB, OsAMTR1, OsZFP185, OsMPS and OsGA2ox3 by targeting to the highly conserved cis-element CNTCSSNNSCAVG except OsSAMS1. Our results demonstrated that OsNAC109 is essential to rice leaf senescence, growth and development through regulating the expression of senescence- and phytohormone-associated genes in rice.


Assuntos
Oryza/crescimento & desenvolvimento , Oryza/genética , Oryza/metabolismo , Reguladores de Crescimento de Plantas/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Alelos , Cloroplastos/ultraestrutura , Regulação da Expressão Gênica de Plantas , Técnicas de Inativação de Genes , Genes de Plantas/genética , Mutação , Fenótipo , Fotossíntese , Folhas de Planta/genética , Folhas de Planta/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Estresse Fisiológico , Fatores de Transcrição , Transcriptoma
8.
Plant Cell ; 33(5): 1682-1705, 2021 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-33561268

RESUMO

Translational recoding, also known as ribosomal frameshifting, is a process that causes ribosome slippage along the messenger RNA, thereby changing the amino acid sequence of the synthesized protein. Whether the chloroplast employs recoding is unknown. I-iota, a plastome mutant of Oenothera (evening primrose), carries a single adenine insertion in an oligoA stretch [11A] of the atpB coding region (encoding the ß-subunit of the ATP synthase). The mutation is expected to cause synthesis of a truncated, nonfunctional protein. We report that a full-length AtpB protein is detectable in I-iota leaves, suggesting operation of a recoding mechanism. To characterize the phenomenon, we generated transplastomic tobacco lines in which the atpB reading frame was altered by insertions or deletions in the oligoA motif. We observed that insertion of two adenines was more efficiently corrected than insertion of a single adenine, or deletion of one or two adenines. We further show that homopolymeric composition of the oligoA stretch is essential for recoding, as an additional replacement of AAA lysine codon by AAG resulted in an albino phenotype. Our work provides evidence for the operation of translational recoding in chloroplasts. Recoding enables correction of frameshift mutations and can restore photoautotrophic growth in the presence of a mutation that otherwise would be lethal.


Assuntos
Cloroplastos/metabolismo , Mutação da Fase de Leitura/genética , Genes de Plantas , Oenothera/genética , Proteínas de Plantas/genética , Biossíntese de Proteínas/genética , Tabaco/genética , Sequência de Aminoácidos , Sequência de Bases , Cloroplastos/ultraestrutura , DNA Complementar/genética , Escherichia coli/metabolismo , Genótipo , Proteínas Mutantes/química , Proteínas Mutantes/metabolismo , Mutação/genética , Peptídeos/química , Peptídeos/metabolismo , Fenótipo , Fotossíntese , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Reprodução
9.
Photosynth Res ; 147(2): 211-227, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33393063

RESUMO

C4-like plants represent the penultimate stage of evolution from C3 to C4 plants. Although Coleataenia prionitis (formerly Panicum prionitis) has been described as a C4 plant, its leaf anatomy and gas exchange traits suggest that it may be a C4-like plant. Here, we reexamined the leaf structure and biochemical and physiological traits of photosynthesis in this grass. The large vascular bundles were surrounded by two layers of bundle sheath (BS): a colorless outer BS and a chloroplast-rich inner BS. Small vascular bundles, which generally had a single BS layer with various vascular structures, also occurred throughout the mesophyll together with BS cells not associated with vascular tissue. The mesophyll cells did not show a radial arrangement typical of Kranz anatomy. These features suggest that the leaf anatomy of C. prionitis is on the evolutionary pathway to a complete C4 Kranz type. Phosphoenolpyruvate carboxylase (PEPC) and pyruvate, Pi dikinase occurred in the mesophyll and outer BS. Glycine decarboxylase was confined to the inner BS. Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) accumulated in the mesophyll and both BSs. C. prionitis had biochemical traits of NADP-malic enzyme type, whereas its gas exchange traits were close to those of C4-like intermediate plants rather than C4 plants. A gas exchange study with a PEPC inhibitor suggested that Rubisco in the mesophyll could fix atmospheric CO2. These data demonstrate that C. prionitis is not a true C4 plant but should be considered as a C4-like plant.


Assuntos
Dióxido de Carbono/metabolismo , Fotossíntese , Poaceae/fisiologia , Cloroplastos/enzimologia , Cloroplastos/fisiologia , Cloroplastos/ultraestrutura , Glicina Desidrogenase (Descarboxilante)/metabolismo , Malato Desidrogenase/metabolismo , Células do Mesofilo/enzimologia , Células do Mesofilo/fisiologia , Células do Mesofilo/ultraestrutura , Fenótipo , Fosfoenolpiruvato Carboxilase/antagonistas & inibidores , Fosfoenolpiruvato Carboxilase/metabolismo , Folhas de Planta/enzimologia , Folhas de Planta/fisiologia , Folhas de Planta/ultraestrutura , Proteínas de Plantas/metabolismo , Poaceae/enzimologia , Poaceae/ultraestrutura , Ribulose-Bifosfato Carboxilase/metabolismo
10.
Biochim Biophys Acta Mol Cell Res ; 1868(5): 118949, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33421532

RESUMO

Pyrenoids are non-membrane bound organelles found in chloroplasts of algae and hornwort plants that can be seen by light-microscopy. Pyrenoids are formed by liquid-liquid phase separation (LLPS) of Rubisco, the primary CO2 fixing enzyme, with an intrinsically disordered multivalent Rubisco-binding protein. Pyrenoids are the heart of algal and hornwort biophysical CO2 concentrating mechanisms, which accelerate photosynthesis and mediate about 30% of global carbon fixation. Even though LLPS may underlie the apparent convergent evolution of pyrenoids, our current molecular understanding of pyrenoid formation comes from a single example, the model alga Chlamydomonas reinhardtii. In this review, we summarise current knowledge about pyrenoid assembly, regulation and structural organization in Chlamydomonas and highlight evidence that LLPS is the general principle underlying pyrenoid formation across algal lineages and hornworts. Detailed understanding of the principles behind pyrenoid assembly, regulation and structural organization within diverse lineages will provide a fundamental understanding of this biogeochemically important organelle and help guide ongoing efforts to engineer pyrenoids into crops to increase photosynthetic performance and yields.2.


Assuntos
Dióxido de Carbono/metabolismo , Chlamydomonas reinhardtii/ultraestrutura , Cloroplastos/ultraestrutura , Organelas/metabolismo , Ciclo do Carbono , Chlamydomonas reinhardtii/metabolismo , Cloroplastos/metabolismo , Extração Líquido-Líquido , Fotossíntese
11.
Plant Cell Physiol ; 62(3): 447-457, 2021 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-33439257

RESUMO

The albino lemma 1 (alm1) mutants of barley (Hordeum vulgare L.) exhibit obvious chlorophyll-deficient hulls. Hulls are seed-enclosing tissues on the spike, consisting of the lemma and palea. The alm1 phenotype is also expressed in the pericarp, culm nodes and basal leaf sheaths, but leaf blades and awns are normal green. A single recessive nuclear gene controls tissue-specific alm1 phenotypic expression. Positional cloning revealed that the ALM1 gene encodes a Golden 2-like (GLK) transcription factor, HvGLK2, belonging to the GARP subfamily of Myb transcription factors. This finding was validated by genetic evidence indicating that all 10 alm1 mutants studied had a lesion in functionally important regions of HvGLK2, including the three alpha-helix domains, an AREAEAA motif and the GCT box. Transmission electron microscopy revealed that, in lemmas of the alm1.g mutant, the chloroplasts lacked thylakoid membranes, instead of stacked thylakoid grana in wild-type chloroplasts. Compared with wild type, alm1.g plants showed similar levels of leaf photosynthesis but reduced spike photosynthesis by 34%. The alm1.g mutant and the alm1.a mutant showed a reduction in 100-grain weight by 15.8% and 23.1%, respectively. As in other plants, barley has HvGLK2 and a paralog, HvGLK1. In flag leaves and awns, HvGLK2 and HvGLK1 are expressed at moderate levels, but in hulls, HvGLK1 expression was barely detectable compared with HvGLK2. Barley alm1/Hvglk2 mutants exhibit more severe phenotypes than glk2 mutants of other plant species reported to date. The severe alm1 phenotypic expression in multiple tissues indicates that HvGLK2 plays some roles that are nonredundant with HvGLK1.


Assuntos
Hordeum/metabolismo , Proteínas de Plantas/fisiologia , Sementes/metabolismo , Fatores de Transcrição/fisiologia , Alelos , Clorofila/metabolismo , Cloroplastos/ultraestrutura , Clonagem Molecular , Genes de Plantas , Hordeum/genética , Microscopia Eletrônica de Transmissão , Mutação/genética , Fotossíntese , Filogenia , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Sementes/crescimento & desenvolvimento , Análise de Sequência de DNA , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
12.
Plant Sci ; 303: 110774, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33487358

RESUMO

Hydrogen peroxide priming has emerged as a powerful strategy to trigger multiple responses involved in plant acclimation that reinforce tolerance to abiotic stresses, including salt stress. Thus, this study aimed to investigate the impact of foliar H2O2 priming on the physiological, biochemical, and ultrastructural traits related to photosynthesis of salt-stressed plants. Besides, we provided comparative leaf metabolomic profiles of Zea mays plants under such conditions. For this, H2O or H2O2 pretreated plants were grown under saline conditions for 12-days. Salinity drastically affected photosynthetic parameters and structural chloroplasts integrity, also increased reactive oxygen species contents promoting disturbance in the plant metabolism when compared to non-saline conditions. Our results suggest that H2O2-pretreated plants improved photosynthetic performance avoiding salinity-induced energy excess and ultrastructural damage by preserving stacking thylakoids. It displayed modulation of some metabolites, as arabitol, glucose, asparagine, and tyrosine, which may contribute to the maintenance of osmotic balance and reduced oxidative stress. Hence, our study brings new insights into an understanding of plant acclimation to salinity by H2O2 priming based on photosynthesis maintenance and metabolite modulation.


Assuntos
Cloroplastos/efeitos dos fármacos , Peróxido de Hidrogênio/farmacologia , Zea mays/metabolismo , Clorofila A/metabolismo , Cloroplastos/metabolismo , Cloroplastos/ultraestrutura , Metabolômica , Microscopia Eletrônica de Transmissão , Pressão Osmótica , Fosfoenolpiruvato Carboxilase/metabolismo , Fotossíntese , Espécies Reativas de Oxigênio/metabolismo , Tolerância ao Sal , Zea mays/efeitos dos fármacos , Zea mays/fisiologia
13.
Dev Cell ; 56(3): 310-324.e7, 2021 02 08.
Artigo em Inglês | MEDLINE | ID: mdl-33357403

RESUMO

Arabidopsis GLYCOGEN SYNTHASE KINASE 3 (GSK3)-like kinases play various roles in plant development, including chloroplast development, but the underlying molecular mechanism is not well defined. Here, we demonstrate that transcription factors GLK1 and GLK2 interact with and are phosphorylated by the BRASSINOSTEROID insensitive2 (BIN2). The loss-of-function mutant of BIN2 and its homologs, bin2-3 bil1 bil2, displays abnormal chloroplast development, whereas the gain-of-function mutant, bin2-1, exhibits insensitivity to BR-induced de-greening and reduced numbers of thylakoids per granum, suggesting that BIN2 positively regulates chloroplast development. Furthermore, BIN2 phosphorylates GLK1 at T175, T238, T248, and T256, and mutations of these phosphorylation sites alter GLK1 protein stability and DNA binding and impair plant responses to BRs/darkness. On the other hand, BRs and darkness repress the BIN2-GLK module to enhance BR/dark-mediated de-greening and impair the formation of the photosynthetic apparatus. Our results thus provide a mechanism by which BRs modulate photomorphogenesis and chloroplast development.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Brassinosteroides/metabolismo , Cloroplastos/metabolismo , Escuridão , Transdução de Sinal Luminoso , Proteínas Quinases/metabolismo , Fatores de Transcrição/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Sequência de Bases , Clorofila/metabolismo , Cloroplastos/ultraestrutura , Cotilédone/fisiologia , Estabilidade Enzimática , Modelos Biológicos , Mutação/genética , Fenótipo , Fosforilação , Ligação Proteica , Proteínas Quinases/genética , Fatores de Transcrição/genética , Transcrição Genética
14.
Int J Mol Sci ; 22(1)2020 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-33375193

RESUMO

Five-day exposure of clary sage (Salvia sclarea L.) to 100 µM cadmium (Cd) in hydroponics was sufficient to increase Cd concentrations significantly in roots and aboveground parts and affect negatively whole plant levels of calcium (Ca) and magnesium (Mg), since Cd competes for Ca channels, while reduced Mg concentrations are associated with increased Cd tolerance. Total zinc (Zn), copper (Cu), and iron (Fe) uptake increased but their translocation to the aboveground parts decreased. Despite the substantial levels of Cd in leaves, without any observed defects on chloroplast ultrastructure, an enhanced photosystem II (PSII) efficiency was observed, with a higher fraction of absorbed light energy to be directed to photochemistry (ΦPSΙΙ). The concomitant increase in the photoprotective mechanism of non-photochemical quenching of photosynthesis (NPQ) resulted in an important decrease in the dissipated non-regulated energy (ΦNO), modifying the homeostasis of reactive oxygen species (ROS), through a decreased singlet oxygen (1O2) formation. A basal ROS level was detected in control plant leaves for optimal growth, while a low increased level of ROS under 5 days Cd exposure seemed to be beneficial for triggering defense responses, and a high level of ROS out of the boundaries (8 days Cd exposure), was harmful to plants. Thus, when clary sage was exposed to Cd for a short period, tolerance mechanisms were triggered. However, exposure to a combination of Cd and high light or to Cd alone (8 days) resulted in an inhibition of PSII functionality, indicating Cd toxicity. Thus, the rapid activation of PSII functionality at short time exposure and the inhibition at longer duration suggests a hormetic response and describes these effects in terms of "adaptive response" and "toxicity", respectively.


Assuntos
Cádmio/toxicidade , Fotossíntese/efeitos dos fármacos , Complexo de Proteína do Fotossistema II/metabolismo , Salvia/efeitos dos fármacos , Clorofila/metabolismo , Clorofila A/metabolismo , Cloroplastos/efeitos dos fármacos , Cloroplastos/metabolismo , Cloroplastos/ultraestrutura , Hormese , Hidroponia/métodos , Microscopia Eletrônica de Transmissão , Fotoquímica , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Salvia/metabolismo
15.
Int J Mol Sci ; 22(1)2020 Dec 25.
Artigo em Inglês | MEDLINE | ID: mdl-33375756

RESUMO

The iron-sulfur subunit (SDH2) of succinate dehydrogenase plays a key role in electron transport in plant mitochondria. However, it is yet unknown whether SDH2 genes are involved in leaf senescence and yield formation. In this study, we isolated a late premature senescence mutant, lps1, in rice (Oryza sativa). The mutant leaves exhibited brown spots at late tillering stage and wilted at the late grain-filling stage and mature stage. In its premature senescence leaves, photosynthetic pigment contents and net photosynthetic rate were reduced; chloroplasts and mitochondria were degraded. Meanwhile, lps1 displayed small panicles, low seed-setting rate and dramatically reduced grain yield. Gene cloning and complementation analysis suggested that the causal gene for the mutant phenotype was OsSDH2-1 (LOC_Os08g02640), in which single nucleotide mutation resulted in an amino acid substitution in the encoded protein. OsSDH2-1 gene was expressed in all organs tested, with higher expression in leaves, root tips, ovary and anthers. OsSDH2-1 protein was targeted to mitochondria. Furthermore, reactive oxygen species (ROS), mainly H2O2, was excessively accumulated in leaves and young panicles of lps1, which could cause premature leaf senescence and affect panicle development and pollen function. Taken together, OsSDH2-1 plays a crucial role in leaf senescence and yield formation in rice.


Assuntos
Envelhecimento/genética , Proteínas Ferro-Enxofre/genética , Oryza/genética , Desenvolvimento Vegetal/genética , Folhas de Planta/genética , Subunidades Proteicas/genética , Succinato Desidrogenase/genética , Cloroplastos/ultraestrutura , Grão Comestível , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Proteínas Ferro-Enxofre/metabolismo , Mutação , Oryza/crescimento & desenvolvimento , Oryza/metabolismo , Fenótipo , Fotossíntese/genética , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Subunidades Proteicas/metabolismo , Característica Quantitativa Herdável , Espécies Reativas de Oxigênio/metabolismo , Reprodução , Succinato Desidrogenase/metabolismo
16.
Nat Commun ; 11(1): 6388, 2020 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-33319777

RESUMO

Evergreen conifers in boreal forests can survive extremely cold (freezing) temperatures during long dark winter and fully recover during summer. A phenomenon called "sustained quenching" putatively provides photoprotection and enables their survival, but its precise molecular and physiological mechanisms are not understood. To unveil them, here we have analyzed seasonal adjustment of the photosynthetic machinery of Scots pine (Pinus sylvestris) trees by monitoring multi-year changes in weather, chlorophyll fluorescence, chloroplast ultrastructure, and changes in pigment-protein composition. Analysis of Photosystem II and Photosystem I performance parameters indicate that highly dynamic structural and functional seasonal rearrangements of the photosynthetic apparatus occur. Although several mechanisms might contribute to 'sustained quenching' of winter/early spring pine needles, time-resolved fluorescence analysis shows that extreme down-regulation of photosystem II activity along with direct energy transfer from photosystem II to photosystem I play a major role. This mechanism is enabled by extensive thylakoid destacking allowing for the mixing of PSII with PSI complexes. These two linked phenomena play crucial roles in winter acclimation and protection.


Assuntos
Transferência de Energia , Fotossíntese/fisiologia , Complexo de Proteína do Fotossistema I/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Pinus sylvestris/metabolismo , Aclimatação , Clorofila , Cloroplastos/metabolismo , Cloroplastos/ultraestrutura , Fluorescência , Cinética , Luz , Processos Fotoquímicos , Complexo de Proteína do Fotossistema I/química , Complexo de Proteína do Fotossistema II/química , Estações do Ano , Temperatura , Tilacoides/metabolismo , Fatores de Tempo , Árvores/metabolismo
17.
Int J Mol Sci ; 21(22)2020 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-33228190

RESUMO

Low temperature stress has a severe impact on the distribution, physiology, and survival of plants in their natural habitats. While numerous studies have focused on the physiological and molecular adjustments to low temperatures, this study provides evidence that cold induced physiological responses coincide with distinct ultrastructural alterations. Three plants from different evolutionary levels and habitats were investigated: The freshwater alga Micrasterias denticulata, the aquatic plant Lemna sp., and the nival plant Ranunculus glacialis. Ultrastructural alterations during low temperature stress were determined by the employment of 2-D transmission electron microscopy and 3-D reconstructions from focused ion beam-scanning electron microscopic series. With decreasing temperatures, increasing numbers of organelle contacts and particularly the fusion of mitochondria to 3-dimensional networks were observed. We assume that the increase or at least maintenance of respiration during low temperature stress is likely to be based on these mitochondrial interconnections. Moreover, it is shown that autophagy and degeneration processes accompany freezing stress in Lemna and R. glacialis. This might be an essential mechanism to recycle damaged cytoplasmic constituents to maintain the cellular metabolism during freezing stress.


Assuntos
Araceae/fisiologia , Autofagia/fisiologia , Cloroplastos/fisiologia , Micrasterias/fisiologia , Mitocôndrias/fisiologia , Ranunculus/fisiologia , Organismos Aquáticos , Araceae/ultraestrutura , Respiração Celular/fisiologia , Cloroplastos/ultraestrutura , Temperatura Baixa , Resposta ao Choque Frio , Retículo Endoplasmático/fisiologia , Retículo Endoplasmático/ultraestrutura , Micrasterias/ultraestrutura , Microscopia Eletrônica de Transmissão , Mitocôndrias/ultraestrutura , Peroxissomos/fisiologia , Peroxissomos/ultraestrutura , Fotossíntese/fisiologia , Células Vegetais/fisiologia , Células Vegetais/ultraestrutura , Ranunculus/ultraestrutura
18.
Protist ; 171(5): 125760, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-33126021

RESUMO

Several species of the genus Tetraselmis (Chlorodendrophyceae, Chlorophyta) were recently discovered to possess unsuspected biomineralization capacities: they produce multiple intracellular inclusions of amorphous calcium carbonate (ACC), called micropearls. Early light-microscopists had spotted rows of refractive granules in some species, although without identifying their mineral nature. Scanning electron microscope (SEM) observations showed that the distribution of the micropearls in the cell forms a pattern, which appears to be characteristic for a given species. The present study shows that this pattern correlates with the shape of the chloroplast, which differs between Tetraselmis species, because micropearls align themselves along the incisions between chloroplast lobes. This was observed both by SEM and in live cells by light microscopy (LM) using Nomarski differential interference contrast. Additionally, molecular phylogenetic analyses, of rbcL and ITS2 gene sequences from diverse strains of Chlorodendrophyceae, corroborated the morphological observations by identifying two groups among nominal Tetraselmis spp. that differ in chloroplast morphology, micropearl arrangement, and ITS2 RNA secondary structure.


Assuntos
Carbonato de Cálcio/metabolismo , Clorófitas/metabolismo , Clorófitas/ultraestrutura , Cloroplastos/ultraestrutura , Biomineralização
19.
Cells ; 9(10)2020 10 20.
Artigo em Inglês | MEDLINE | ID: mdl-33092216

RESUMO

Black spot disease, caused by Alternaria brassicicola in Brassica species, is one of the most devastating diseases all over the world, especially since there is no known fully resistant Brassica cultivar. In this study, the visualization of black spot disease development on Brassica oleracea var. capitata f. alba (white cabbage) leaves and subsequent ultrastructural, molecular and physiological investigations were conducted. Inter- and intracellular hyphae growth within leaf tissues led to the loss of host cell integrity and various levels of organelle disintegration. Severe symptoms of chloroplast damage included the degeneration of chloroplast envelope and grana, and the loss of electron denseness by stroma at the advanced stage of infection. Transcriptional profiling of infected leaves revealed that photosynthesis was the most negatively regulated biological process. However, in infected leaves, chlorophyll and carotenoid content did not decrease until 48 hpi, and several chlorophyll a fluorescence parameters, such as photosystem II quantum yield (Fv/Fm), non-photochemical quenching (NPQ), or plant vitality parameter (Rdf) decreased significantly at 24 and 48 hpi compared to control leaves. Our results indicate that the initial stages of interaction between B. oleracea and A. brassicicola are not uniform within an inoculation site and show a complexity of host responses and fungal attempts to overcome host cell defense mechanisms. The downregulation of photosynthesis at the early stage of this susceptible interaction suggests that it may be a part of a host defense strategy, or, alternatively, that chloroplasts are targets for the unknown virulence factor(s) of A. brassicicola. However, the observed decrease of photosynthetic efficiency at the later stages of infection is a result of the fungus-induced necrotic lesion expansion.


Assuntos
Alternaria/ultraestrutura , Brassica/genética , Brassica/microbiologia , Regulação para Baixo , Interações Hospedeiro-Patógeno/genética , Fotossíntese , Doenças das Plantas/microbiologia , Transcrição Genética , Alternaria/fisiologia , Brassica/fisiologia , Brassica/ultraestrutura , Clorofila A/metabolismo , Cloroplastos/metabolismo , Cloroplastos/ultraestrutura , Suscetibilidade a Doenças , Regulação da Expressão Gênica de Plantas , Ontologia Genética , Células do Mesofilo/microbiologia , Células do Mesofilo/ultraestrutura , Fotossíntese/genética , Folhas de Planta/microbiologia , Folhas de Planta/ultraestrutura , Fatores de Tempo
20.
Plant Cell Rep ; 39(12): 1719-1741, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32955612

RESUMO

KEY MESSAGE: Defence responses of cyst nematode and/or wheat curl mite infested barley engage the altered reactive oxygen species production, antioxidant machinery, carbon dioxide assimilation and photosynthesis efficiency. The primary aim of this study was to determine how barley responds to two pests infesting separately or at once; thus barley was inoculated with Heterodera filipjevi (Madzhidov) Stelter (cereal cyst nematode; CCN) and Aceria tosichella Keifer (wheat curl mite; WCM). To verify hypothesis about the involvement of redox metabolism and photosynthesis in barley defence responses, biochemical, photosynthesis efficiency and chlorophyll a fluorescence measurements as well as transmission electron microscopy were implemented. Inoculation with WCM (apart from or with CCN) brought about a significant suppression in the efficiency of electron transport outside photosystem II reaction centres. This limitation was an effect of diminished pool of rapidly reducing plastoquinone and decreased total electron carriers. Infestation with WCM (apart from or with CCN) also significantly restricted the electron transport on the photosystem I acceptor side, therefore produced reactive oxygen species oxidized lipids in cells of WCM and double infested plants and proteins in cells of WCM-infested plants. The level of hydrogen peroxide was significantly decreased in double infested plants because of glutathione-ascorbate cycle involvement. The inhibition of nitrosoglutathione reductase promoted the accumulation of S-nitrosoglutathione increasing antioxidant capacity in cells of double infested plants. Moreover, enhanced arginase activity in WCM-infested plants could stimulate synthesis of polyamines participating in plant antioxidant response. Infestation with WCM (apart from or with CCN) significantly reduced the efficiency of carbon dioxide assimilation by barley leaves, whereas infection only with CCN expanded photosynthesis efficiency. These were accompanied with the ultrastructural changes in chloroplasts during CCN and WCM infestation.


Assuntos
Hordeum/parasitologia , Interações Hospedeiro-Parasita/fisiologia , Ácaros/patogenicidade , Folhas de Planta/metabolismo , Tylenchoidea/patogenicidade , Animais , Cloroplastos/parasitologia , Cloroplastos/ultraestrutura , Enzimas/metabolismo , Hordeum/fisiologia , Fenóis/metabolismo , Fotossíntese/fisiologia , Folhas de Planta/parasitologia , Proteínas de Plantas/metabolismo , Carbonilação Proteica , Espécies Reativas de Oxigênio/metabolismo
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