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1.
Aquat Toxicol ; 229: 105669, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33142158

RESUMO

Polybrominated diphenyl ethers (PBDEs) are ubiquitously distributed persistent organic pollutants (POPs) in marine environments. Phytoplankton are the entrance of PBDEs entering to biotic environments from abiotic environments, while the responding mechanisms of phytoplankton to PBDEs have not been full established. Therefore, we chose the model diatom Thalassiosira pseudonana in this study, by integrating whole transcriptome analysis with physiological-biochemical data, to reveal the molecular responding mechanisms of T. pseudonana to the toxicity of BDE-47. Our results indicated the changes of genes expressions correlated to the physiological-biochemical changes, and there were multiple molecular mechanisms of T. pseudonana responding to the toxicity of BDE-47: Gene expressions evidence explained the suppression of light reaction and proved the occurrence of cellular oxidative stress; In the meanwhile, up-regulations of genes in pathways involving carbon metabolisms happened, including the Calvin cycle, glycolysis, TCA cycle, fatty acid synthesis, and triacylglycerol synthesis; Lastly, DNA damage was found and three outcome including DNA repair, cell cycle arrest and programmed cell death (PCD) happened, which could finally inhibit the cell division and population growth of T. pseudonana. This study presented the most complete molecular responding mechanisms of phytoplankton cells to PBDEs, and provided valuable information of various PBDEs-sensitive genes with multiple functions for further research involving organic pollutants and phytoplankton.


Assuntos
Diatomáceas/genética , Perfilação da Expressão Gênica , Éteres Difenil Halogenados/toxicidade , Testes de Toxicidade , Apoptose/efeitos dos fármacos , Carbono/metabolismo , Dano ao DNA , Diatomáceas/efeitos dos fármacos , Diatomáceas/fisiologia , Regulação da Expressão Gênica/efeitos dos fármacos , Glutationa/metabolismo , Éteres Difenil Halogenados/metabolismo , Complexos de Proteínas Captadores de Luz/genética , Complexos de Proteínas Captadores de Luz/metabolismo , Redes e Vias Metabólicas/efeitos dos fármacos , Nitrogênio/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Oxigênio/metabolismo , Fotossíntese/efeitos dos fármacos , Complexo de Proteína do Fotossistema II/genética , Complexo de Proteína do Fotossistema II/metabolismo , Fitoplâncton/efeitos dos fármacos , Fitoplâncton/genética , Transcriptoma/genética , Poluentes Químicos da Água/toxicidade
2.
Bioresour Technol ; 318: 124039, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32896711

RESUMO

The study aimed at understanding the biochemical and molecular level modifications in Desmodesmus sp. under lipid inducing stress conditions. The low-temperature (5 °C) incubation and nitrogen starvation reduced the PS II electron transport in microalga with a maximum reduction of 50-57% in ET0/ABS values. The PS II electron transport recovered in UV treated cultures after an initial reduction of 87-93% in ET0/ABS values. A 2.7-4.4 fold increase in ROS and MDA levels was observed under low-temperature incubation, and nitrogen starvation. The UV treatment caused 1.3-2.4 fold higher ROS and MDA levels than control. The low-temperature incubated, nitrogen starved, and UV treated cultures showed 2.4-4 fold higher acc D gene expression. A higher rbc L gene expression was observed under low-temperature stress. The study showed modifications in PS II electron transport, oxidative status, and expression of acc D and rbc L genes under stress conditions.


Assuntos
Microalgas , Complexo de Proteína do Fotossistema II , Transporte de Elétrons , Microalgas/genética , Microalgas/metabolismo , Nitrogênio , Estresse Oxidativo , Complexo de Proteína do Fotossistema II/genética , Complexo de Proteína do Fotossistema II/metabolismo
3.
Sci Rep ; 10(1): 15412, 2020 09 22.
Artigo em Inglês | MEDLINE | ID: mdl-32963291

RESUMO

The Arabidopsis genome is methylated in CG and non-CG (CHG, and CHH in which H stands for A, T, or C) sequence contexts. DNA methylation has been suggested to be critical for seed development, and CHH methylation patterns change during stratification and germination. In plants, CHH methylation occurs mainly through the RNA-directed DNA methylation (RdDM) pathway. To test for an involvement of the RdDM pathway in chloroplast development, we analyzed seedling greening and the maximum quantum yield of photosystem II (Fv/Fm) in Arabidopsis thaliana seedlings perturbed in components of that pathway. Neither seedling greening nor Fv/Fm in seedlings and adult plants were affected in this comprehensive set of mutants, indicating that alterations in the RdDM pathway do not affect chloroplast development. Application of inhibitors like lincomycin or norflurazon inhibits greening of seedlings and represses the expression of photosynthesis-related genes including LIGHT HARVESTING CHLOROPHYLL A/B BINDING PROTEIN1.2 (LHCB1.2) in the nucleus. Our results indicate that the LHCB1.2 promoter is poorly methylated under both control conditions and after inhibitor treatment. Therefore no correlation between LHCB1.2 mRNA transcription and methylation changes of the LHCB1.2 promoter could be established. Moreover, we conclude that perturbations in the RdDM pathway do not interfere with gun signaling.


Assuntos
Cloroplastos/genética , Metilação de DNA/genética , Genoma de Planta/genética , RNA de Plantas/genética , Transdução de Sinais/genética , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Clorofila A/genética , Regulação da Expressão Gênica de Plantas/genética , Germinação/genética , Complexo de Proteína do Fotossistema II/genética , Regiões Promotoras Genéticas/genética , Plântula/genética , Sementes/genética
4.
Sci Rep ; 10(1): 14095, 2020 08 24.
Artigo em Inglês | MEDLINE | ID: mdl-32839512

RESUMO

Natural coastal microbial mat communities are multi-species assemblages that experience fluctuating environmental conditions and are shaped by resource competition as well as by cooperation. Laboratory studies rarely address the natural complexity of microbial communities but are usually limited to homogeneous mono-cultures of key species grown in liquid media. The mat-forming filamentous cyanobacteria Lyngbya aestuarii and Coleofasciculus chthonoplastes were cultured under different conditions to investigate the expression of circadian clock genes and genes that are under their control. The cyanobacteria were grown in liquid medium or on a solid substrate (glass beads) as mono- or as co-cultures under a light-dark regime and subsequently transferred to continuous light. TaqMan-probe based qPCR assays were used to quantify the expression of the circadian clock genes kaiA, kaiB, and kaiC, and of four genes that are under control of the circadian clock: psbA, nifH, ftsZ, and prx. Expression of kaiABC was influenced by co-culturing the cyanobacteria and whether grown in liquid media or on a solid substrate. Free-running (i.e. under continuous light) expression cycle of the circadian clock genes was observed in L. aestuarii but not in C. chthonoplastes. In the former organism, maximum expression of psbA and nifH occurred temporally separated and independent of the light regime, although the peak shifted in time when the culture was transferred to continuous illumination. Although functionally similar, both species of cyanobacteria displayed different 24-h transcriptional patterns in response to the experimental treatments, suggesting that their circadian clocks have adapted to different life strategies adopted by these mat-forming cyanobacteria.


Assuntos
Relógios Circadianos/genética , Ritmo Circadiano/fisiologia , Cianobactérias/metabolismo , Regulação Bacteriana da Expressão Gênica/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Relógios Circadianos/fisiologia , Ritmo Circadiano/genética , Peptídeos e Proteínas de Sinalização do Ritmo Circadiano/genética , Peptídeos e Proteínas de Sinalização do Ritmo Circadiano/metabolismo , Técnicas de Cocultura , Cianobactérias/genética , Cianobactérias/fisiologia , Proteínas do Citoesqueleto/genética , Proteínas do Citoesqueleto/metabolismo , Expressão Gênica/genética , /metabolismo , Microbiota/fisiologia , Oxirredutases/genética , Oxirredutases/metabolismo , Complexo de Proteína do Fotossistema II/genética , Complexo de Proteína do Fotossistema II/metabolismo , Transcrição Genética/genética
5.
Proc Natl Acad Sci U S A ; 117(33): 19705-19712, 2020 08 18.
Artigo em Inglês | MEDLINE | ID: mdl-32747579

RESUMO

Photosystem II (PS II) captures solar energy and directs charge separation (CS) across the thylakoid membrane during photosynthesis. The highly oxidizing, charge-separated state generated within its reaction center (RC) drives water oxidation. Spectroscopic studies on PS II RCs are difficult to interpret due to large spectral congestion, necessitating modeling to elucidate key spectral features. Herein, we present results from time-dependent density functional theory (TDDFT) calculations on the largest PS II RC model reported to date. This model explicitly includes six RC chromophores and both the chlorin phytol chains and the amino acid residues <6 Å from the pigments' porphyrin ring centers. Comparing our wild-type model results with calculations on mutant D1-His-198-Ala and D2-His-197-Ala RCs, our simulated absorption-difference spectra reproduce experimentally observed shifts in known chlorophyll absorption bands, demonstrating the predictive capabilities of this model. We find that inclusion of both nearby residues and phytol chains is necessary to reproduce this behavior. Our calculations provide a unique opportunity to observe the molecular orbitals that contribute to the excited states that are precursors to CS. Strikingly, we observe two high oscillator strength, low-lying states, in which molecular orbitals are delocalized over ChlD1 and PheD1 as well as one weaker oscillator strength state with molecular orbitals delocalized over the P chlorophylls. Both these configurations are a match for previously identified exciton-charge transfer states (ChlD1 +PheD1 -)* and (PD2 +PD1 -)*. Our results demonstrate the power of TDDFT as a tool, for studies of natural photosynthesis, or indeed future studies of artificial photosynthetic complexes.


Assuntos
Proteínas de Bactérias/química , Cianobactérias/metabolismo , Complexo de Proteína do Fotossistema II/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Clorofila/química , Clorofila/metabolismo , Cianobactérias/química , Cianobactérias/genética , Cinética , Modelos Moleculares , Fotossíntese , Complexo de Proteína do Fotossistema II/genética , Complexo de Proteína do Fotossistema II/metabolismo
6.
Proc Natl Acad Sci U S A ; 117(35): 21775-21784, 2020 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-32817480

RESUMO

The D1 reaction center protein of photosystem II (PSII) is subject to light-induced damage. Degradation of damaged D1 and its replacement by nascent D1 are at the heart of a PSII repair cycle, without which photosynthesis is inhibited. In mature plant chloroplasts, light stimulates the recruitment of ribosomes specifically to psbA mRNA to provide nascent D1 for PSII repair and also triggers a global increase in translation elongation rate. The light-induced signals that initiate these responses are unclear. We present action spectrum and genetic data indicating that the light-induced recruitment of ribosomes to psbA mRNA is triggered by D1 photodamage, whereas the global stimulation of translation elongation is triggered by photosynthetic electron transport. Furthermore, mutants lacking HCF136, which mediates an early step in D1 assembly, exhibit constitutively high psbA ribosome occupancy in the dark and differ in this way from mutants lacking PSII for other reasons. These results, together with the recent elucidation of a thylakoid membrane complex that functions in PSII assembly, PSII repair, and psbA translation, suggest an autoregulatory mechanism in which the light-induced degradation of D1 relieves repressive interactions between D1 and translational activators in the complex. We suggest that the presence of D1 in this complex coordinates D1 synthesis with the need for nascent D1 during both PSII biogenesis and PSII repair in plant chloroplasts.


Assuntos
Proteínas de Arabidopsis/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Ligação à Clorofila/metabolismo , Cloroplastos/metabolismo , Fatores de Iniciação em Eucariotos/metabolismo , Luz , Proteínas de Membrana/metabolismo , Fotossíntese , Complexo de Proteína do Fotossistema II/genética , Plantas/genética , Biossíntese de Proteínas/fisiologia , Processamento de Proteína Pós-Traducional/fisiologia , RNA Mensageiro/metabolismo , Ribossomos/metabolismo , Transcrição Genética , Zea mays/genética , Zea mays/metabolismo
7.
Biochim Biophys Acta Bioenerg ; 1861(12): 148301, 2020 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-32860756

RESUMO

In photosystem II (PSII), photosynthetic water oxidation occurs at the O2-evolving complex (OEC), a tetramanganese-calcium cluster that cycles through light-induced redox intermediates (S0-S4) to produce oxygen from two substrate water molecules. The OEC is surrounded by a hydrogen-bonded network of amino-acid residues that plays a crucial role in proton transfer and substrate water delivery. Previously, we found that D1-S169 was crucial for water oxidation and its mutation to alanine perturbed the hydrogen-bonding network. In this study, we demonstrate that the activation energy for the S2 to S1 transition of D1-S169A PSII is higher than wild-type PSII with a ~1.7-2.7× slower rate of charge recombination with QA- relative to wild-type PSII. Arrhenius analysis of the decay kinetics shows an Ea of 5.87 ± 1.15 kcal mol-1 for decay back to the S1 state, compared to 0.80 ± 0.13 kcal mol-1 for the wild-type S2 state. In addition, we find that ammonia does not affect the S2-state EPR signal, indicating that ammonia does not bind to the Mn cluster in D1-S169A PSII. Finally, a QM/MM analysis indicates that an additional water molecule binds to the Mn4 ion in place of an oxo ligand O5 in the S2 state of D1-S169A PSII. The altered S2 state of D1-S169A PSII provides insight into the S2➔S3 state transition.


Assuntos
Substituição de Aminoácidos/genética , Complexo de Proteína do Fotossistema II/química , Complexo de Proteína do Fotossistema II/genética , Amônia/farmacologia , Elétrons , Cinética , Modelos Moleculares , Proteínas Mutantes/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Multimerização Proteica , Teoria Quântica , Synechocystis/metabolismo
8.
PLoS One ; 15(7): e0235622, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32614898

RESUMO

Volvox sect. Volvox is an interesting group of green algae; it comprises mostly monoicous species, but evidence suggests an evolution towards dioicy. Based on cultured strains originating from Thailand, we describe Volvox longispiniferus, a novel species in Volvox sect. Volvox. This species is distinguished from others in the section by the large number of sperm packets in its monoicous sexual spheroids and by the long spines on its zygote wall. Phylogenetic analyses indicate that V. longispiniferus is distinct from the other species of two monophyletic groups within Volvox sect. Volvox. In addition, the novel species produces more zygotes when different cultures are combined compared with a single culture, suggesting a preference for outcrossing.


Assuntos
Volvox/classificação , Cloroplastos/genética , DNA Ribossômico/classificação , DNA Ribossômico/genética , Complexo de Proteína do Fotossistema II/genética , Filogenia , Ribulose-Bifosfato Carboxilase/classificação , Ribulose-Bifosfato Carboxilase/genética , Tailândia , Volvox/genética
9.
Sci Rep ; 10(1): 9322, 2020 06 09.
Artigo em Inglês | MEDLINE | ID: mdl-32518304

RESUMO

The effects of jasmonic acid (JA) and methyl jasmonate (Me-JA) on photosynthetic efficiency and expression of some photosystem (PSII) related in different cultivars of Brassica oleracea L. (var. italica, capitata, and botrytis) were investigated. Plants raised from seeds subjected to a pre-sowing soaking treatment of varying concentrations of JA and Me-JA showed enhanced photosynthetic efficiency in terms of qP and chlorophyll fluorescence. Maximum quantum efficiency of PSII (Fv/Fm) was increased over that in the control seedlings. This enhancement was more pronounced in the Me-JA-treated seedlings compared to that in JA-treated ones. The expression of PSII genes was differentially regulated among the three varieties of B. oleracea. The gene PsbI up-upregulated in var. botrytis after treatment of JA and Me-JA, whereas PsbL up-regulated in capitata and botrytis after supplementation of JA. The gene PsbM showed many fold enhancements in these expressions in italica and botrytis after treatment with JA. However, the expression of the gene PsbM increased by both JA and Me-JA treatments. PsbTc(p) and PsbTc(n) were also found to be differentially expressed which revealed specificity with the variety chosen as well as JA or Me-JA treatments. The RuBP carboxylase activity remained unaffected by either JA or Me-JA supplementation in all three varieties of B. oleracea L. The data suggest that exogenous application of JA and Me-JA to seeds before germination could influence the assembly, stability, and repair of PS II in the three varieties of B. oleracea examined. Furthermore, this improvement in the PS II machinery enhanced the photosynthetic efficiency of the system and improved the photosynthetic productivity in terms of saccharides accumulation.


Assuntos
Acetatos/farmacologia , Brassica/efeitos dos fármacos , Brassica/fisiologia , Ciclopentanos/farmacologia , Oxilipinas/farmacologia , Complexo de Proteína do Fotossistema II/genética , Brassica/genética , Brassica/crescimento & desenvolvimento , Metabolismo dos Carboidratos/efeitos dos fármacos , Carotenoides/metabolismo , Clorofila/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Brotos de Planta/efeitos dos fármacos , Brotos de Planta/crescimento & desenvolvimento , Ribulose-Bifosfato Carboxilase/metabolismo , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Sementes/efeitos dos fármacos , Sementes/metabolismo , Açúcares/metabolismo
10.
J Plant Physiol ; 251: 153189, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32526555

RESUMO

Throughout 3.5 billion years of evolution, photosynthesis of land plants has developed a complicated antenna system to cope with the ever-changing environments. The antenna system of photosystem (PS) II includes the outer antennae and inner antennae. The inner antennae CP43 and CP47, located in the closest peripheral of PSII reaction center (RC), play important roles in facilitating excitation energy transport from the outer antennae to the PSII RC. Although PSII RC is the last station of energy transport, it is the inner antenna CP47, not the RC, which possesses the lowest energy level in PSII. Berteroa incana (B. incana), which is a vascular plant grown in the Gobi region, can sustain very high photosynthesis capacity under very high light conditions. It has been discovered that the thylakoid membrane of B. incana possesses a unique low fluorescence emission spectrum because the fluorescence emission of CP47 (695 nm) is the main fluorescence emission peak of PSII. In this paper, the thylakoid membrane, isolated from B. incana grown under a light condition of 100 µM photons m-2 s-1 and subjected to high light treatment (1600 µM photons m-2 s-1 for 1.5 h or 3 h) was employed for the research. It has been found that the high fluorescence emission of CP47 decreased remarkably upon exposure to the high light treatment. Further observation revealed that the drastic changes in the CP47 fluorescence emission were accompanied by a slight reduction in the amount of CP47 and an enhancement of the CP29-LHCII-CP24 assembly. It is proposed that CP47 enables the functional switch between the excitation energy transfer towards PSII RC, and the overexcitation quenching in the PSII core. Together with CP43, CP47 plays important roles in regulating excitation energy distribution in PSII core complexes.


Assuntos
Adaptação Fisiológica/genética , Brassicaceae/fisiologia , Complexos de Proteínas Captadores de Luz/genética , Complexo de Proteína do Fotossistema II/genética , Luz Solar , Brassicaceae/genética , Complexos de Proteínas Captadores de Luz/metabolismo , Fotossíntese , Complexo de Proteína do Fotossistema II/metabolismo , Espectrometria de Fluorescência , Estresse Fisiológico , Luz Solar/efeitos adversos , Tilacoides/metabolismo
11.
Sci Rep ; 10(1): 6770, 2020 04 21.
Artigo em Inglês | MEDLINE | ID: mdl-32317747

RESUMO

Although light is essential for photosynthesis, when in excess, it may damage the photosynthetic apparatus, leading to a phenomenon known as photoinhibition. Photoinhibition was thought as a light-induced damage to photosystem II; however, it is now clear that even photosystem I may become very vulnerable to light. One main characteristic of light induced damage to photosystem II (PSII) is the increased turnover of the reaction center protein, D1: when rate of degradation exceeds the rate of synthesis, loss of PSII activity is observed. With respect to photosystem I (PSI), an excess of electrons, instead of an excess of light, may be very dangerous. Plants possess a number of mechanisms able to prevent, or limit, such damages by safe thermal dissipation of light energy (non-photochemical quenching, NPQ), slowing-down of electron transfer through the intersystem transport chain (photosynthesis-control, PSC) in co-operation with the Proton Gradient Regulation (PGR) proteins, PGR5 and PGRL1, collectively called as short-term photoprotection mechanisms, and the redistribution of light between photosystems, called state transitions (responsible of fluorescence quenching at PSII, qT), is superimposed to these short term photoprotective mechanisms. In this manuscript we have generated a number of higher order mutants by crossing genotypes carrying defects in each of the short-term photoprotection mechanisms, with the final aim to obtain a direct comparison of their role and efficiency in photoprotection. We found that mutants carrying a defect in the ΔpH-dependent photosynthesis-control are characterized by photoinhibition of both photosystems, irrespectively of whether PSBS-dependent NPQ or state transitions defects were present or not in the same individual, demonstrating the primary role of PSC in photoprotection. Moreover, mutants with a limited capability to develop a strong PSBS-dependent NPQ, were characterized by a high turnover of the D1 protein and high values of Y(NO), which might reflect energy quenching processes occurring within the PSII reaction center.


Assuntos
Proteínas de Arabidopsis/genética , Proteínas de Membrana/genética , Complexo de Proteínas do Centro de Reação Fotossintética/genética , Complexo de Proteína do Fotossistema I/genética , Complexo de Proteína do Fotossistema II/genética , Arabidopsis/genética , Arabidopsis/fisiologia , Genótipo , Concentração de Íons de Hidrogênio , Luz , Fotossíntese/genética , Fotossíntese/efeitos da radiação , Complexo de Proteína do Fotossistema I/efeitos da radiação , Complexo de Proteína do Fotossistema II/efeitos da radiação
12.
Photosynth Res ; 144(1): 49-62, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32152819

RESUMO

Zostera marina, a fully submerged marine angiosperm with a unique evolutionary history associated with its terrestrial origin, has distinct photochemical characteristics caused by its oxygen-evolving complex (OEC) being prone to deactivation in visible light. Based on the present phylogenetic analysis, the chloroplast NADPH dehydrogenase-like (NDH) complex was found to be completed in of Z. marina, unlike other marine plants, suggesting its crucial role. Thus, the responses of electron transport to irradiation were investigated through multiple chlorophyll fluorescence techniques and Western blot analysis. Moreover, the respective contribution of the two photosystem I cyclic electron flow (PSI-CEF) pathways to the generation of trans-thylakoid proton gradient (∆pH) was also examined using inhibitors. The contributions of the two PSI-CEF pathways to ∆pH were similar; furthermore, there was a trade-off between the two pathways under excess irradiation: the PGR5/L1-dependent PSI-CEF decreased gradually following its activation during the initial illumination, while NDH-dependent PSI-CEF was activated gradually with exposure duration. OEC inactivation was continuously under excess irradiation, which exhibits a positive linear correlation with the activation of NDH-dependent PSI-CEF. We suggest that PGR5/L1-dependent PSI-CEF was preferentially activated to handle the excess electron caused by the operation of OEC during the initial illumination. Subsequently, the increasing OEC inactivation with exposure duration resulted in a deficit of electrons. Limited electrons from PSI might preferentially synthesize NADPH, which could support the function of NDH-dependent PSI-CEF to generate ∆pH and ATP via reducing ferredoxin, thereby maintaining OEC stability.


Assuntos
Proteínas de Arabidopsis/metabolismo , Magnoliopsida/metabolismo , Complexo de Proteína do Fotossistema I/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Proteínas de Plantas/metabolismo , Zosteraceae/metabolismo , Proteínas de Arabidopsis/genética , Elétrons , Magnoliopsida/genética , Complexo de Proteína do Fotossistema I/genética , Complexo de Proteína do Fotossistema II/genética , Proteínas de Plantas/genética , Zosteraceae/genética
13.
Sci Rep ; 10(1): 1959, 2020 02 06.
Artigo em Inglês | MEDLINE | ID: mdl-32029804

RESUMO

The final stage of leaf ontogenesis is represented by senescence, a highly regulated process driven by a sequential cellular breakdown involving, as the first step, chloroplast dismantling with consequent reduction of photosynthetic efficiency. Different processes, such as pigment accumulation, could protect the vulnerable photosynthetic apparatus of senescent leaves. Although several studies have produced transcriptomic data on foliar senescence, just few works have attempted to explain differences in red and green leaves throughout ontogenesis. In this work, a transcriptomic approach was used on green and red leaves of Prunus cerasifera to unveil molecular differences from leaf maturity to senescence. Our analysis revealed a higher gene regulation in red leaves compared to green ones, during leaf transition. Most of the observed DEGs were shared and involved in transcription factor activities, senescing processes and cell wall remodelling. Significant differences were detected in cellular functions: genes related to photosystem I and II were highly down-regulated in the green genotype, whereas transcripts involved in flavonoid biosynthesis, such as UDP glucose-flavonoid-3-O-glucosyltransferase (UFGT) were exclusively up-regulated in red leaves. In addition, cellular functions involved in stress response (glutathione-S-transferase, Pathogen-Related) and sugar metabolism, such as three threalose-6-phosphate synthases, were activated in senescent red leaves. In conclusion, data suggests that P. cerasifera red genotypes can regulate a set of genes and molecular mechanisms that cope with senescence, promoting more advantages during leaf ontogenesis than compared to the green ones.


Assuntos
Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Folhas de Planta/crescimento & desenvolvimento , Proteínas de Plantas/genética , Prunus domestica/fisiologia , Senescência Celular/genética , Cor , Regulação para Baixo , Flavonoides/biossíntese , Glucosiltransferases/genética , Glucosiltransferases/metabolismo , Complexo de Proteína do Fotossistema I/genética , Complexo de Proteína do Fotossistema I/metabolismo , Complexo de Proteína do Fotossistema II/genética , Complexo de Proteína do Fotossistema II/metabolismo , Proteínas de Plantas/metabolismo , Transcriptoma , Regulação para Cima
14.
Artigo em Inglês | MEDLINE | ID: mdl-31958679

RESUMO

Salicylic acid (SA) is involved in several responses associated with plant development and defence against biotic and abiotic stress, but its role on photosynthetic regulation is still under debate. This work investigated energy conversion processes and related gene expression in the brachytic mutant of sunflower lingering hope (linho). This mutant was characterized by a higher ratio between the free SA form and its conjugate form SA O-ß-D-glucoside (SAG) compared to wild type (WT), without significant changes in the endogenous level of abscisic acid and hydrogen peroxide. The mutant showed an inhibition of photosynthesis due to a combination of both stomatal and non-stomatal limitations, although the latter seemed to play a major role. The reduced carboxylation efficiency was associated with a down-regulation of the gene expression for both the large and small subunits of Rubisco and the Rubisco activase enzyme. Moreover, linho showed an alteration of photosystem II (PSII) functionality, with reduced PSII photochemistry, increased PSII excitation pressure and decreased thermal energy dissipation of excessive light energy. These responses were associated with a lower photosynthetic pigments concentration and a reduced expression of genes encoding for light-harvesting chlorophyll a/b binding proteins (i.e. HaLhcA), chlorophyll binding subunits of PSII proteins (i.e. HaPsbS and HaPsbX), phytoene synthase enzyme and a different expression level for genes related to PSII repair cycle, such as HaPsbA and HaPsbD. The concomitant stimulation of respiratory metabolism, suggests that linho activated a coordinate modulation of chloroplast and mitochondria activities to compensate the energy imbalance and regulate energy conversion processes.


Assuntos
Regulação da Expressão Gênica de Plantas , Helianthus , Ácido Salicílico , Clorofila/metabolismo , Helianthus/genética , Helianthus/metabolismo , Mutação , Fotossíntese/genética , Complexo de Proteína do Fotossistema II/genética , Folhas de Planta/genética , Folhas de Planta/metabolismo , Ácido Salicílico/metabolismo
15.
J Nat Med ; 74(1): 282-293, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31587135

RESUMO

The dried fruits of Terminalia plant (Combretaceae) called "Samo" have been used as herbal medicine in Thai traditional medicine. Four "Samo" crude drugs, namely, Samo thai, Samo thed, Samo dee-ngu, and Samo phiphek, are used as the main ingredients in Triphala and Trisamo recipes. Their commercial products are available in processed and powdered form, but are difficult to authenticate by conventional methods. In this study, we aimed to discriminate species of genus Terminalia for the identification of their crude drugs by a DNA barcoding technique. A total of 208 closely related nucleotide sequences were obtained from nine Terminalia species collected from Thailand and the DDBJ/EMBL/GenBank database. An effective DNA barcode marker was selected from six DNA loci (matK, rbcL, psbA-trnH, ITS, ITS1, and ITS2) and their two-locus combination. All sequences were analyzed by three major methods: (1) BLAST search; (2) the genetic divergence method using Kimura 2-parameter (K2P) distance matrices; and (3) tree topology analysis based on the neighbor-joining method. Comparison of the six candidate DNA loci indicated that ITS identified Terminalia with 100% accuracy at the species and genus levels in the BLAST1 method. ITS2 showed the highest K2P variability. The data from the single markers and the two-locus combinations revealed that only the two-locus combinations, namely, the combinations of rbcL, ITS, ITS1, and ITS2 with psbA-trnH, clearly discriminated all the species. From the results of DNA sequence analysis and the three methods, ITS2 is recommended for the identification of Terminalia species to supplement psbA-trnH.


Assuntos
Código de Barras de DNA Taxonômico/métodos , DNA Intergênico/genética , Complexo de Proteína do Fotossistema II/genética , Terminalia/classificação , Terminalia/genética , Sequência de Bases , DNA de Plantas/genética , Marcadores Genéticos/genética , Fitoterapia , Extratos Vegetais/química , Plantas Medicinais/genética , Análise de Sequência de DNA , Tailândia
16.
Biochim Biophys Acta Bioenerg ; 1861(1): 148086, 2020 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-31678434

RESUMO

The Mn4CaO5 cluster, the catalytic center of water oxidation in photosystem II (PSII), is coordinated by six carboxylate and one imidazole ligands. The roles of these ligands in the water oxidation mechanism remain largely unknown. In this study, we constructed a D1-D170H mutant, in which the Asp ligand bridging Mn and Ca ions was replaced with His, in the cyanobacterium Synechocystis sp. PCC 6803, and analyzed isolated PSII core complexes using Fourier transform infrared (FTIR) difference spectroscopy and mass spectrometry (MS). The S2-minus-S1 FTIR difference spectrum of the PSII complexes of the D1-D170H mutant showed features virtually identical to those of the wild-type PSII. MS analysis further showed that ~70% of D1 proteins from the PSII complexes of D1-D170H possessed the wild-type amino acid sequence, although only the mutated sequence was detected in genomic DNA in the same batch of cells for PSII preparations. In contrast, a D1-S169A mutant as a control showed a modified FTIR spectrum and only a mutated D1 protein. It is thus concluded that the FTIR spectrum of the D1-D170H mutant actually reflects that of wild-type PSII, whereas the Mn4CaO5 cluster is not formed in PSII with D1-D170H mutation. Although the mechanism of production of the wild-type D1 protein in the D1-D170H mutant is unknown at present, a caution is necessary in the analysis of site-directed mutants of crucial residues in the D1 protein, and mutation has to be confirmed not only at the DNA level but also at the amino acid level.


Assuntos
Proteínas de Bactérias/metabolismo , Mutação de Sentido Incorreto , Complexo de Proteína do Fotossistema II/metabolismo , Synechocystis/enzimologia , Substituição de Aminoácidos , Proteínas de Bactérias/genética , Domínio Catalítico , Espectrometria de Massas , Mutagênese Sítio-Dirigida , Complexo de Proteína do Fotossistema II/genética , Espectroscopia de Infravermelho com Transformada de Fourier , Synechocystis/genética
17.
Plant Biol (Stuttg) ; 22(4): 735-743, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31886945

RESUMO

The EGY3 protein is a homologue of site-2 proteases, which are intramembrane zinc metalloproteases. EGY3 itself lacks proteolytic activity due to the absence of a zinc-binding motif. Plentiful evidence indicates that such intramembrane 'pseudoproteases' play significant roles in many diverse processes occurring within the cell. However, the physiological functions of EGY3, as well as its subcellular localization, remain unknown. The subcellular localization of EGY3 protein was investigated using Arabidopsis thaliana protoplasts transformed with EGY3-GFP fusion protein, and immunoblot experiments using the total leaf protein extract, as well as highly purified chloroplasts and fractions of stroma, envelope and thylakoid membrane proteins. The physiological role of EGY3 was studied using two A. thaliana mutant lines devoid of EGY3 protein. Chlorophyll a fluorescence measurement was performed and the egy3 mutant sensitivity to photoinhibition was investigated. Additionally, the abundance of thylakoid membrane complexes was established using blue native gel electrophoresis. We present experimental evidence for thylakoid membrane localization of the EGY3 protein. We show that egy3 mutants display increased value of the non-photochemical quenching parameter and significantly slower recovery rate after photoinhibitory treatment. This was associated with a decrease in the level of proteases involved in photosystem II recovery, Deg1 and FtsH2/8.


Assuntos
Proteínas de Arabidopsis , Cloroplastos , Peptídeo Hidrolases , Arabidopsis/enzimologia , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Cloroplastos/enzimologia , Mutação , Peptídeo Hidrolases/genética , Peptídeo Hidrolases/metabolismo , Complexo de Proteína do Fotossistema II/genética , Transporte Proteico
18.
Artigo em Inglês | MEDLINE | ID: mdl-31887556

RESUMO

Potato (Solanum tuberosum) mutant (ST) lacking one isoform of manganese-stabilizing protein (MSPI) of photosystem II exhibited besides spontaneous tuberization also growth changes with strongly impaired root system development. Previous studies revealed marked changes in carbohydrate levels and allocation within ST plant body. To verify causal relationship between changed carbohydrate balance and root growth restriction we engaged dark grown sucrose-supplied root organ-cultures of ST plants to exclude/confirm shoot effects. Unexpectedly, in ST root cultures we observed large alterations in growth and architecture as well as saccharide status similar to those found in the intact plant roots. The gene expression analysis, however, proved PsbO1 transcript (coding MSPI protein) neither in ST nor in WT root-organ cultures. Therefore, the results point to indirect effects of PsbO1 allele absence connected possibly with some epigenetic modulations.


Assuntos
Fotossíntese/genética , Complexo de Proteína do Fotossistema II/metabolismo , Proteínas de Plantas/genética , Raízes de Plantas/metabolismo , Solanum tuberosum/genética , Alelos , Metabolismo dos Carboidratos/genética , Células Cultivadas , Regulação da Expressão Gênica de Plantas/genética , Regulação da Expressão Gênica de Plantas/fisiologia , Manganês/metabolismo , Proteínas Mutantes/química , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Mutação , Fotossíntese/efeitos da radiação , Complexo de Proteína do Fotossistema II/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Tubérculos/genética , Tubérculos/crescimento & desenvolvimento , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Solanum tuberosum/crescimento & desenvolvimento , Sacarose/metabolismo
19.
PLoS One ; 14(11): e0225375, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31770415

RESUMO

We developed a simple method to apply CRISPR interference by modifying an existing plasmid pCRISPathBrick containing the native S. pyogenes CRISPR assembly for Synechocystis PCC6803 and named it pCRPB1010. The technique presented here using deadCas9 is easier to implement for gene silencing in Synechocystis PCC6803 than other existing techniques as it circumvents the genome integration and segregation steps thereby significantly shortens the construction of the mutant strains. We executed CRISPR interference against well characterized photosynthetic genes to get a clear phenotype to validate the potential of pCRPB1010 and presented the work as a "proof of concept". Targeting the non-template strand of psbO gene resulted in decreased amount of PsbO and 50% decrease in oxygen evolution rate. Targeting the template strand of psbA2 and psbA3 genes encoding the D1 subunit of photosystem II (PSII) using a single spacer against the common sequence span of the two genes, resulted in full inhibition of both genes, complete abolition of D1 protein synthesis, complete loss of oxygen evolution as well as photoautotrophic growth arrest. This is the first report of a single plasmid based, completely lesion free and episomal expression and execution of CRISPR interference in Synechocystis PCC6803.


Assuntos
Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Complexo de Proteína do Fotossistema II/genética , Plasmídeos/genética , Synechocystis/genética , Proteínas de Bactérias/genética , Regulação Bacteriana da Expressão Gênica , Oxigênio/metabolismo , Fotossíntese , Synechocystis/metabolismo
20.
Genes (Basel) ; 10(11)2019 11 19.
Artigo em Inglês | MEDLINE | ID: mdl-31752425

RESUMO

Leaf premature senescence largely determines maize (Zea mays L.) grain yield and quality. A natural recessive premature-senescence mutant was selected from the breeding population, and near-isogenic lines were constructed using Jing24 as the recurrent parent. In the near-isogenic lines, the dominant homozygous material was wild-type (WT), and the recessive material of early leaf senescence was the premature-senescence-type ZmELS5. To identify major genes and regulatory mechanisms involved in leaf senescence, a transcriptome analysis of the ZmELS5 and WT near-isogenic lines (NILs) was performed. A total of 8,796 differentially expressed transcripts were identified between ZmELS5 and WT, including 3,811 up-regulated and 4,985 down-regulated transcripts. By combining gene ontology, Kyoto Encyclopedia of Genes and Genomes, gene set, and transcription factor enrichment analyses, key differentially expressed genes were screened. The senescence regulatory network was predicted based on these key differentially expressed genes, which indicated that the senescence process is mainly regulated by bHLH, WRKY, and AP2/EREBP family transcription factors, leading to the accumulations of jasmonic acid and ethylene. This causes stress responses and reductions in the chlorophyll a/b-binding protein activity level. Then, decreased ATP synthase activity leads to increased photosystem II photodamage, ultimately leading to leaf senescence.


Assuntos
Senescência Celular/genética , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Redes Reguladoras de Genes , Proteínas de Plantas/genética , Zea mays/fisiologia , Complexos de ATP Sintetase/genética , Complexos de ATP Sintetase/metabolismo , Albinismo Oculocutâneo , Clorofila A , Ciclopentanos/metabolismo , Etilenos/metabolismo , Perfilação da Expressão Gênica , Genes de Plantas/genética , Oxilipinas/metabolismo , Complexo de Proteína do Fotossistema II/genética , Complexo de Proteína do Fotossistema II/metabolismo , Reguladores de Crescimento de Planta/metabolismo , Folhas de Planta/fisiologia , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
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