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1.
Cytogenet Genome Res ; 160(2): 100-109, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32146470

RESUMO

Chloroplasts and mitochondria are semi-autonomous organelles and have their own genomes (cytoplasmic genomes). Physical radiations (e.g., γ-rays) have been widely used in artificial mutation induction for plant germplasm enhancement and for breeding new cultivars. However, little is known at the genomic level about which kind of cytoplasmic mutations and/or characteristics could be induced in plants. The present study aimed to investigate the type, number, and distribution of inheritable cytoplasmic mutations induced by γ-rays in rice (Oryza sativa L.). Six plants were selected from the 2nd generation (M2) populations after γ-ray (137Cs) irradiation of the rice cultivar Nipponbare, 2 each for the 3 irradiation doses (150, 250, and 350 Gy), and their genomes were sequenced on an Illumina platform. Together with the whole-genome sequencing data of 3 external Nipponbare control plants, single-base substitutions (SBSs) and insertions/deletions (InDels) in chloroplast (cp) and mitochondrial (mt) genomes were identified and analyzed in-depth using bioinformatic tools. The majority of SBSs and InDels identified were background mutations in the 6 M2 plants, and the number of induced mutations varied greatly among the plants. Most induced mutations were present in a heterogeneous state, reflecting the fact that multiple cp and mt copies existed in the progenitor cells. The induced mutations were distributed in different genomic regions in the 6 M2 plants, including exonic regions, but none of them was predicted to cause nonsynonymous mutations or frameshifts. Our study thus revealed, at the genomic level, characteristics of cytoplasmic mutations induced by γ-rays in rice.


Assuntos
Raios gama/efeitos adversos , Mutação , Oryza/efeitos da radiação , Sequenciamento Completo do Genoma/métodos , Cloroplastos/genética , Cloroplastos/efeitos da radiação , Genoma de Planta/efeitos da radiação , Sequenciamento de Nucleotídeos em Larga Escala , Mitocôndrias/genética , Mitocôndrias/efeitos da radiação , Oryza/genética , Proteínas de Plantas/genética , Proteínas de Plantas/efeitos da radiação , Sementes/genética , Sementes/efeitos da radiação
2.
Elife ; 82019 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-31612858

RESUMO

In response to proteotoxic stress, chloroplasts communicate with the nuclear gene expression system through a chloroplast unfolded protein response (cpUPR). We isolated Chlamydomonas reinhardtii mutants that disrupt cpUPR signaling and identified a gene encoding a previously uncharacterized cytoplasmic protein kinase, termed Mars1-for mutant affected in chloroplast-to-nucleus retrograde signaling-as the first known component in cpUPR signal transmission. Lack of cpUPR induction in MARS1 mutant cells impaired their ability to cope with chloroplast stress, including exposure to excessive light. Conversely, transgenic activation of cpUPR signaling conferred an advantage to cells undergoing photooxidative stress. Our results indicate that the cpUPR mitigates chloroplast photodamage and that manipulation of this pathway is a potential avenue for engineering photosynthetic organisms with increased tolerance to chloroplast stress.


Assuntos
Chlamydomonas reinhardtii/genética , Cloroplastos/genética , Regulação da Expressão Gênica de Plantas , Transdução de Sinal Luminoso/genética , Proteínas de Plantas/genética , Proteínas Serina-Treonina Quinases/genética , Resposta a Proteínas não Dobradas , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Núcleo Celular/genética , Núcleo Celular/metabolismo , Núcleo Celular/efeitos da radiação , Chlamydomonas reinhardtii/metabolismo , Chlamydomonas reinhardtii/efeitos da radiação , Cloroplastos/metabolismo , Cloroplastos/efeitos da radiação , Testes Genéticos , Luz , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Oxirredução , Estresse Oxidativo , Fotossíntese/genética , Proteínas de Plantas/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Serina Endopeptidases/genética , Serina Endopeptidases/metabolismo
3.
Plant Sci ; 286: 1-6, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31300135

RESUMO

The excessive and harmful light energy absorbed by the photosystem (PS) II of higher plants is dissipated as heat through a protective mechanism termed non-photochemical quenching (NPQ) of chlorophyll fluorescence. PsbS-knock-out (KO) mutants lack the trans-thylakoid proton gradient (ΔpH)-dependent part of NPQ. To elucidate the molecular mechanism of NPQ, we investigated its dependency on oxygen. The development of NPQ in wild-type (WT) rice under low-oxygen (LO) conditions was reduced to more than 50% of its original value. However, under high-oxygen (HO) conditions, the NPQ of both WT and PsbS-KO mutants recovered. Moreover, WT and PsbS-KO mutant leaves infiltrated with the ΔpH dissipating uncoupler nigericin showed increased NPQ values under HO conditions. The experiments using intact chloroplasts and protoplasts of Arabidopsis thaliana supported that the LO effects observed in rice leaves were not due to carbon dioxide deficiency. There was a noticeable 90% reduction in the half-time of P700 oxidation rate in LO-treated leaves compared with that of WT control leaves, but the HO treatment did not significantly change the half-time of P700 oxidation rate. Overall, the results obtained here indicate that the stroma of the PsbS-KO plants could be potentially under O2 deficiency. Because the functions of PsbS in rice leaves are likely to be similar to those in other higher plants, our findings offer novel insights into the role of oxygen in the development of NPQ.


Assuntos
Adaptação Fisiológica/efeitos da radiação , Arabidopsis/metabolismo , Oryza/metabolismo , Oxigênio/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Arabidopsis/efeitos da radiação , Cloroplastos/metabolismo , Cloroplastos/efeitos da radiação , Oryza/efeitos da radiação , Complexo de Proteína do Fotossistema II/genética , Folhas de Planta/genética , Folhas de Planta/fisiologia , Folhas de Planta/efeitos da radiação , Protoplastos/metabolismo , Protoplastos/efeitos da radiação
4.
Plant Cell Physiol ; 60(10): 2243-2254, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31198960

RESUMO

Chloroplast movement is important for plants to avoid photodamage and to perform efficient photosynthesis. Phototropins are blue light receptors in plants that function in chloroplast movement, phototropism, stomatal opening, and they also affect plant growth and development. In this study, full-length cDNAs of two PHOTOTROPIN genes, PaPHOT1 and PaPHOT2, were cloned from a moth orchid Phalaenopsis aphrodite, and their functions in chloroplast movement were investigated. Phylogenetic analysis showed that PaPHOT1 and PaPHOT2 orthologs were highly similar to PHOT1 and PHOT2 of the close relative Phalaenopsis equestris, respectively, and clustered with monocots PHOT1 and PHOT2 orthologs, respectively. Phalaenopsis aphrodite expressed a moderate level of PaPHOT1 under low blue light of 5 µmol�m-2�s-1 (BL5) and a high levels of PaPHOT1 at >BL100. However, PaPHOT2 was expressed at low levels at BL100. Analysis of light-induced chloroplast movements using the SPAD method indicated that orchid accumulated chloroplasts at BL25 and significant chloroplast avoidance movement was observed at >BL100. Virus-induced gene silencing of PaPHOTs in orchids showed decreased gene expression of PaPHOTs and reduced both chloroplast accumulation and avoidance responses. Heterologous expression of PaPHOT1 in Arabidopsis phot1phot2 double mutant recovered chloroplast accumulation response at BL5, but neither PaPHOT1 nor PaPHOT2 was able to restore mutant chloroplast avoidance at BL100. Overall, this study showed that phototropins mediate chloroplast movement in Phalaenopsis orchid is blue light-dependent but their function is slightly different from Arabidopsis which might be due to gene evolution.


Assuntos
Orchidaceae/fisiologia , Fototropinas/metabolismo , Fototropismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Cloroplastos/metabolismo , Cloroplastos/efeitos da radiação , DNA Complementar/genética , Expressão Gênica , Inativação Gênica , Hibridização In Situ , Luz , Mutação , Orchidaceae/genética , Orchidaceae/efeitos da radiação , Fotossíntese , Fototropinas/genética , Filogenia , Folhas de Planta/genética , Folhas de Planta/fisiologia , Folhas de Planta/efeitos da radiação , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo
5.
Int J Mol Sci ; 20(6)2019 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-30889814

RESUMO

As a secondary messenger, calcium participates in various physiological and biochemical reactions in plants. Photosynthesis is the most extensive biosynthesis process on Earth. To date, researchers have found that some chloroplast proteins have Ca2+-binding sites, and the structure and function of some of these proteins have been discussed in detail. Although the roles of Ca2+ signal transduction related to photosynthesis have been discussed, the relationship between calcium and photosynthesis is seldom systematically summarized. In this review, we provide an overview of current knowledge of calcium's role in photosynthesis.


Assuntos
Cálcio/metabolismo , Fotossíntese , Carbono/metabolismo , Cloroplastos/metabolismo , Cloroplastos/efeitos da radiação , Luz , Fotossíntese/efeitos da radiação , Estômatos de Plantas/fisiologia , Estômatos de Plantas/efeitos da radiação
6.
Mol Plant ; 12(2): 199-214, 2019 02 04.
Artigo em Inglês | MEDLINE | ID: mdl-30639120

RESUMO

Over the past few years, three photorespiratory bypasses have been introduced into plants, two of which led to observable increases in photosynthesis and biomass yield. However, most of the experiments were carried out using Arabidopsis under controlled environmental conditions, and the increases were only observed under low-light and short-day conditions. In this study, we designed a new photorespiratory bypass (called GOC bypass), characterized by no reducing equivalents being produced during a complete oxidation of glycolate into CO2 catalyzed by three rice-self-originating enzymes, i.e., glycolate oxidase, oxalate oxidase, and catalase. We successfully established this bypass in rice chloroplasts using a multi-gene assembly and transformation system. Transgenic rice plants carrying GOC bypass (GOC plants) showed significant increases in photosynthesis efficiency, biomass yield, and nitrogen content, as well as several other CO2-enriched phenotypes under both greenhouse and field conditions. Grain yield of GOC plants varied depending on seeding season and was increased significantly in the spring. We further demonstrated that GOC plants had significant advantages under high-light conditions and that the improvements in GOC plants resulted primarily from a photosynthetic CO2-concentrating effect rather than from improved energy balance. Taken together, our results reveal that engineering a newly designed chloroplastic photorespiratory bypass could increase photosynthetic efficiency and yield of rice plants grown in field conditions, particularly under high light.


Assuntos
Cloroplastos/metabolismo , Cloroplastos/efeitos da radiação , Engenharia Genética , Luz , Oryza/citologia , Oryza/genética , Fotossíntese/genética , Dióxido de Carbono/metabolismo , Respiração Celular/genética , Respiração Celular/efeitos da radiação , Metabolismo Energético/genética , Metabolismo Energético/efeitos da radiação , Oryza/metabolismo , Oryza/efeitos da radiação , Fenótipo , Fotossíntese/efeitos da radiação , Plantas Geneticamente Modificadas
7.
Plant Physiol Biochem ; 135: 51-60, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30500518

RESUMO

Chloroplast movement mediated by the plant-specific phototropin blue light photoreceptors is crucial for plants to cope with fluctuating light conditions. While chloroplasts accumulate at weak light-illuminated areas, chloroplast avoidance response mediated primarily by the phototropin2 (phot2) receptor is induced by strong light illumination. Although extensive studies have been performed on phot2-mediated chloroplast avoidance in the model plant Arabidopsis, little is known on the role of the corresponding PHOT2 orthologs in chloroplast movement in cotton. In this study, we found that chloroplast avoidance movement also occurs in the tetraploid G. hirsutum and two diploid species, G. arboreum and G. raimondii, albeit with distinct features. Further bioinformatics and genetic analysis identified the cotton PHOT2 ortholog, GhPHOT2-1, which retained a conserved role in plant chloroplast avoidance movement under strong blue light. Ghphot2-1was localized in the plasma membrane and formed aggregates after high blue light irradiation. Constitutive expression of GhPHOT2-1 restored chloroplast avoidance and accumulation response, as well as phototropism, and leaf flattening characteristics of the Arabidopsis phot2 or phot1 phot2 mutants. On the contrary, silencing of GhPHOT2-1 by virus-induced gene silencing (VIGS) disrupted high blue light-induced chloroplast avoidance movement and caused photo damage in cotton leaves. Taken together, these findings demonstrated that GhPHOT2-1 is a conserved PHOT2 ortholog in regulating chloroplast avoidance and the other aforementioned phot2-mediated responses, implicating its potential role for improving high light tolerance in cotton cultivars.


Assuntos
Cloroplastos/efeitos da radiação , Genes de Plantas/fisiologia , Gossypium/efeitos da radiação , Fototropinas/fisiologia , Arabidopsis/genética , Arabidopsis/fisiologia , Arabidopsis/efeitos da radiação , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/fisiologia , Membrana Celular/fisiologia , Membrana Celular/efeitos da radiação , Cloroplastos/fisiologia , Genes de Plantas/genética , Gossypium/genética , Gossypium/fisiologia , Luz , Fototropinas/genética , Filogenia , Folhas de Planta/fisiologia , Folhas de Planta/efeitos da radiação , Proteínas de Plantas/genética , Proteínas de Plantas/fisiologia , Reação em Cadeia da Polimerase em Tempo Real , Alinhamento de Sequência
8.
Biochim Biophys Acta Bioenerg ; 1860(1): 102-110, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30414926

RESUMO

Light state transitions (STs) is a reversible physiological process that oxygenic photosynthetic organisms use in order to minimize imbalances in the electronic excitation delivery to the reaction centers of Photosystems I and II, and thus to optimize photosynthesis. STs have been studied extensively in plants, green algae, red algae and cyanobacteria, but sparsely in algae with secondary red algal plastids, such as diatoms and haptophytes, despite their immense ecological significance. In the present work, we examine whether the haptophyte alga Phaeocystis antarctica, and dinoflagellate cells that host kleptoplasts derived from P. antarctica, both endemic in the Ross Sea, Antarctica, are capable of light adaptive STs. In these organisms, Chl a fluorescence can be excited either by direct light absorption, or indirectly by electronic excitation (EE) transfer from ultraviolet light absorbing mycosporine-like amino acids (MAAs) to Chl a (Stamatakis et al., Biochim. Biophys. Acta 1858 [2017] 189-195). Here we show that, on adaptation to PS II-selective light, dark-adapted P. antarctica cells shift from light state 1 (ST1; more EE ending up in PS II) to light state 2 (ST2; more EE ending up in PS I), as revealed by the spectral distribution of directly-excited Chl a fluorescence and by changes in the macro-organization of pigment-protein complexes evidenced by circular dichroism (CD) spectroscopy. In contrast, no STs are clearly detected in the case of the kleptoplast-hosting dinoflagellate cells, and in the case of indirectly excited Chls a, via MAAs, in P. antarctica cells.


Assuntos
Dinoflagelados/efeitos da radiação , Transferência de Energia , Haptófitas/efeitos da radiação , Complexo de Proteína do Fotossistema I/fisiologia , Complexo de Proteína do Fotossistema II/fisiologia , Clorofila A/metabolismo , Cloroplastos/efeitos da radiação , Transporte de Elétrons , Fluorescência , Luz , Plastídeos
9.
Physiol Plant ; 167(2): 188-204, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30467859

RESUMO

Research has begun to elucidate the signal transduction pathway(s) that control cellular responses to changes in mitochondrial status. Important tools in such studies are chemical inhibitors used to initiate mitochondrial dysfunction. This study compares the effect of different inhibitors and treatment conditions on the transcript amount of nuclear genes specifically responsive to mitochondrial dysfunction in leaf of Nicotiana tabacum L. cv. Petit Havana. The Complex III inhibitors antimycin A (AA) and myxothiazol (MYXO), and the Complex V inhibitor oligomycin (OLIGO), each increased the transcript amount of the mitochondrial dysfunction genes. Transcript responses to OLIGO were greater during treatment in the dark than in the light, and the dark treatment resulted in cell death. In the dark, transcript responses to AA and MYXO were similar to one another, despite MYXO leading to cell death. In the light, transcript responses to AA and MYXO diverged, despite cell viability remaining high with either inhibitor. This divergent response may be due to differential signaling from the chloroplast because only AA also inhibited cyclic electron transport, resulting in a strong acceptor-side limitation in photosystem I. In the light, chemical inhibition of chloroplast electron transport reduced transcript responses to AA, while having no effect on the response to MYXO, and increasing the response to OLIGO. Hence, when studying mitochondrial dysfunction signaling, different inhibitor and treatment combinations differentially affect linked processes (e.g. chloroplast function and cell fate) that then contribute to measured responses. Therefore, inhibitor and treatment conditions should be chosen to align with specific study goals.


Assuntos
Cloroplastos/metabolismo , Mitocôndrias/metabolismo , Transdução de Sinais , Tabaco/genética , Antimicina A/farmacologia , Cloroplastos/efeitos da radiação , Transporte de Elétrons/efeitos dos fármacos , Complexo III da Cadeia de Transporte de Elétrons/antagonistas & inibidores , Luz , Metacrilatos/farmacologia , Mitocôndrias/efeitos da radiação , ATPases Mitocondriais Próton-Translocadoras/antagonistas & inibidores , Oligomicinas/farmacologia , Complexo de Proteína do Fotossistema I/efeitos dos fármacos , Complexo de Proteína do Fotossistema I/genética , Complexo de Proteína do Fotossistema I/metabolismo , Folhas de Planta/genética , Folhas de Planta/fisiologia , Folhas de Planta/efeitos da radiação , Tiazóis/farmacologia , Tabaco/fisiologia , Tabaco/efeitos da radiação
10.
New Phytol ; 221(2): 866-880, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30169890

RESUMO

The photosynthetic machinery of plants must be regulated to maximize the efficiency of light reactions and CO2 fixation. Changes in free Ca2+ in the stroma of chloroplasts have been observed at the transition between light and darkness, and also in response to stress stimuli. Such Ca2+ dynamics have been proposed to regulate photosynthetic capacity. However, the molecular mechanisms of Ca2+ fluxes in the chloroplasts have been unknown. By employing a Ca2+ reporter-based approach, we identified two chloroplast-localized Ca2+ transporters in Arabidopsis thaliana, BICAT1 and BICAT2, that determine the amplitude of the darkness-induced Ca2+ signal in the chloroplast stroma. BICAT2 mediated Ca2+ uptake across the chloroplast envelope, and its knockout mutation strongly dampened the dark-induced [Ca2+ ]stroma signal. Conversely, this Ca2+ transient was increased in knockout mutants of BICAT1, which transports Ca2+ into the thylakoid lumen. Knockout mutation of BICAT2 caused severe defects in chloroplast morphology, pigmentation and photosynthetic light reactions, rendering bicat2 mutants barely viable under autotrophic growth conditions, while bicat1 mutants were less affected. These results show that BICAT transporters play a role in chloroplast Ca2+ homeostasis. They are also involved in the regulation of photosynthesis and plant productivity. Further work will be required to reveal whether the effect on photosynthesis is a direct result of their role as Ca2+ transporters.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Cálcio/metabolismo , Arabidopsis/fisiologia , Arabidopsis/efeitos da radiação , Proteínas de Arabidopsis/genética , Proteínas de Cloroplastos/genética , Proteínas de Cloroplastos/metabolismo , Cloroplastos/metabolismo , Cloroplastos/efeitos da radiação , Escuridão , Genes Reporter , Homeostase , Fotossíntese , Estômatos de Plantas/genética , Estômatos de Plantas/fisiologia , Estômatos de Plantas/efeitos da radiação , Protoplastos
11.
New Phytol ; 222(1): 349-365, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30449034

RESUMO

High light and high temperature (HLHT) stress may become more frequent and severe as the climate changes, affecting crop growth and resulting in reduced production. However, the mechanism of the response to HLHT stress in rice is not yet fully understood. In the present study, we screened a rice mutant library using HLHT conditions and isolated an HLHT-sensitive mutant, local lesions 1 (ls1), which showed decreased pigment contents, defective stomata and chloroplasts, and a local lesions phenotype under HLHT. We characterized and cloned LS1 by map-based cloning and genetic complementation. LS1 encodes the A subunit of the RNase H2 complex (RNASEH2A). Terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) and comet assays indicated that mutation of LS1 led to severe DNA damage under HLHT stress. Furthermore, we found excessive reactive oxygen species (ROS) accumulation in the ls1 mutant under HLHT stress. Exogenous antioxidants eased the local lesions phenotype of the ls1 mutant under HLHT. DNA damage caused by HLHT stress induces ROS accumulation, which causes the injury and apoptosis of leaf cells in the ls1 mutant. These results enhance our understanding of the regulatory mechanism in the response to HLHT stress in higher plants.


Assuntos
Dano ao DNA , Luz , Mutação/genética , Oryza/metabolismo , Oryza/efeitos da radiação , Proteínas de Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Temperatura , Antioxidantes/metabolismo , Sequência de Bases , Morte Celular/efeitos da radiação , Forma Celular/efeitos da radiação , Clorofila/metabolismo , Cloroplastos/metabolismo , Cloroplastos/efeitos da radiação , Cloroplastos/ultraestrutura , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Fenótipo , Folhas de Planta/citologia , Folhas de Planta/metabolismo , Folhas de Planta/ultraestrutura , Proteínas de Plantas/genética , Subunidades Proteicas/metabolismo , Ribonucleases/metabolismo , Frações Subcelulares/metabolismo
12.
Plant Signal Behav ; 14(1): 1554469, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30574829

RESUMO

Autophagy delivers cytosolic components to lysosomes and the vacuole for degradation. This pathway prevents starvation through bulk degradation and recycling of cytoplasmic components, and maintains cellular homeostasis through selective elimination of damaged proteins and organelles. Autophagic delivery processes are categorized into three types: macroautophagy, microautophagy, and chaperone-mediated autophagy. During macroautophagy, nascent, double membrane-bound vesicles termed autophagosomes sequester a portion of cytoplasm and deliver it to the vacuole/lysosomes. Molecular genetic studies in budding yeasts have identified a set of AUTOPHAGY (ATG) genes required for autophagosome formation. Although microautophagy involves the direct lysosomal/vacuolar engulfment and incorporation of a target into the lumen rather than the formation of autophagosomes, the membrane dynamics and possible roles of ATGs during microautophagy are under investigation. Our recent study revealed an ATG-dependent microautophagy process in plants, during which chloroplasts damaged by high visible light (HL) are selectively eliminated. Here, we discuss the membrane dynamics of the plant microautophagy that enables the transport of whole chloroplasts into the vacuole.


Assuntos
Autofagia/efeitos da radiação , Cloroplastos/metabolismo , Luz , Cloroplastos/efeitos da radiação , /efeitos da radiação
13.
J Zhejiang Univ Sci B ; 19(8): 581-595, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30070082

RESUMO

Under different red (R):blue (B) photon flux ratios, the growth performance of rapeseed (Brassica napus L.) is significantly different. Rapeseed under high R ratios shows shade response, while under high B ratios it shows sun-type morphology. Rapeseed under monochromatic red or blue light is seriously stressed. Transcriptomic and proteomic methods were used to analyze the metabolic pathway change of rapeseed (cv. "Zhongshuang 11") leaves under different R:B photon flux ratios (including 100R:0B%, 75R:25B%, 25R:75B%, and 0R:100B%), based on digital gene expression (DGE) and two-dimensional gel electrophoresis (2-DE). For DGE analysis, 2054 differentially expressed transcripts (|log2(fold change)|≥1, q<0.005) were detected among the treatments. High R ratios (100R:0B% and 75R:25B%) enhanced the expression of cellular structural components, mainly the cell wall and cell membrane. These components participated in plant epidermis development and anatomical structure morphogenesis. This might be related to the shade response induced by red light. High B ratios (25R:75B% and 0R:100B%) promoted the expression of chloroplast-related components, which might be involved in the formation of sun-type chloroplast induced by blue light. For 2-DE analysis, 37 protein spots showed more than a 2-fold difference in expression among the treatments. Monochromatic light (ML; 100R:0B% and 0R:100B%) stimulated accumulation of proteins associated with antioxidation, photosystem II (PSII), DNA and ribosome repairs, while compound light (CL; 75R:25B% and 25R:75B%) accelerated accumulation of proteins associated with carbohydrate, nucleic acid, amino acid, vitamin, and xanthophyll metabolisms. These findings can be useful in understanding the response mechanisms of rapeseed leaves to different R:B photon flux ratios.


Assuntos
Brassica rapa/genética , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Luz , Transcrição Genética , Brassica napus/genética , Brassica napus/efeitos da radiação , Brassica rapa/efeitos da radiação , Carbono/química , Cloroplastos/genética , Cloroplastos/efeitos da radiação , Biologia Computacional , Eletroforese em Gel Bidimensional , Processamento de Imagem Assistida por Computador , Espectrometria de Massas , Redes e Vias Metabólicas , Nitrogênio/química , Fótons , Complexo de Proteína do Fotossistema II/genética , Folhas de Planta/genética , Folhas de Planta/efeitos da radiação , Proteínas de Plantas/genética , Proteoma , Ribossomos , Transcriptoma
14.
FEBS Lett ; 592(18): 3111-3115, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-30076598

RESUMO

In order to maintain enzyme stability and activity, chloroplasts use two systems of thiol-disulfide reductases for the control of redox-dependent properties of proteins. Previous studies have revealed that plastid-localized thioredoxins (TRX) and the NADPH-dependent thioredoxin reductase C (NTRC) are important for the reduction of cysteine residues of enzymes involved in chlorophyll synthesis. Very recently, it was shown that the pale green phenotype of the ntrc mutant is suppressed when the contents of 2-cysteine peroxiredoxins (2CP) A and B are decreased. Here, we show that suppression of the ntrc phenotype results from a recovery of wild-type-like redox control of chlorophyll biosynthesis enzymes in ntrc/2cp mutants. The presented results support the conclusion that TRXs rather than NTRC are the predominant reductases mediating the redox-regulation of these enzymes.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Clorofila/biossíntese , Tiorredoxinas/metabolismo , Arabidopsis/genética , Arabidopsis/efeitos da radiação , Proteínas de Arabidopsis/genética , Cloroplastos/genética , Cloroplastos/metabolismo , Cloroplastos/efeitos da radiação , Luz , Mutação , Fotossíntese/genética , Fotossíntese/efeitos da radiação , Plântula/genética , Plântula/metabolismo , Plântula/efeitos da radiação , Tiorredoxina Dissulfeto Redutase/genética , Tiorredoxina Dissulfeto Redutase/metabolismo , Tiorredoxinas/genética
15.
Plant Signal Behav ; 13(8): e1482174, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30047818

RESUMO

Seedlings of wild-type and etiolate mutant plants of Anthurium andraeanum cultivar 'Sonate' were treated for 15 d with different light intensities (20, 100, and 400 µmol·m-2·s-1) to analyze leaf plastid development and pigment content. Significant changes appeared in treated seedlings, including in leaf color, plastid ultrastructure, chloroplast development gene AaGLK expression, chlorophyll and anthocyanin contents, and protoplast shape. Wild-type and etiolated plants exhibited different plastid structures under the same light condition. The results suggest that light intensity is a crucial environmental factor influencing plastid development and leaf color formation in the A. andraeanum cultivar 'Sonate'.


Assuntos
Antocianinas/metabolismo , Araceae/metabolismo , Clorofila/metabolismo , Cloroplastos/metabolismo , Luz , Araceae/efeitos da radiação , Cloroplastos/efeitos da radiação , Pigmentação/efeitos da radiação
16.
Int J Mol Sci ; 19(7)2018 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-29937503

RESUMO

The chloroplast relies on proteins encoded in the nucleus, synthesized in the cytosol and subsequently transported into chloroplast through the protein complexes Toc and Tic (Translocon at the outer/inner membrane of chloroplasts). A Tic complex member, Tic55, contains a redox-related motif essential for protein import into chloroplasts in peas. However, Tic55 is not crucial for protein import in Arabidopsis. Here, a tic55-II-knockout mutant of Arabidopsis thaliana was characterized for Tic55 localization, its relationship with other translocon proteins, and its association with plant leaf senescence when compared to the wild type. Individually darkened leaves (IDLs) obtained through dark-induced leaf senescence were used to demonstrate chlorophyll breakdown and its relationship with plant senescence in the tic55-II-knockout mutant. The IDLs of the tic55-II-knockout mutant contained higher chlorophyll concentrations than those of the wild type. Our microarray analysis of IDLs during leaf senescence identified seven senescence-associated genes (SAGs) that were downregulated in the tic55-II-knockout mutant: ASP3, APG7, DIN2, DIN11, SAG12, SAG13, and YLS9. Real-time quantitative PCR confirmed the reliability of microarray analysis by showing the same expression patterns with those of the microarray data. Thus, Tic55 functions in dark-induced aging in A. thaliana by indirectly regulating downstream SAGs expression. In addition, the expression of four NAC genes, including ANAC003, ANAC010, ANAC042, and ANAC075 of IDL treated tic55-II-knockout mutant appeared to be downregulated. Yeast one hybrid assay revealed that only ANAC003 promoter region can be bound by MYB108, suggesting that a MYB-NAC regulatory network is involved in dark-stressed senescence.


Assuntos
Proteínas de Arabidopsis/genética , Clorofila/metabolismo , Regulação da Expressão Gênica de Plantas , Proteínas de Membrana Transportadoras/genética , Fatores de Transcrição/genética , Sequência de Aminoácidos , Arabidopsis/classificação , Arabidopsis/genética , Arabidopsis/metabolismo , Arabidopsis/efeitos da radiação , Proteínas de Arabidopsis/metabolismo , Senescência Celular , Cloroplastos/genética , Cloroplastos/metabolismo , Cloroplastos/efeitos da radiação , Escuridão , Técnicas de Inativação de Genes , Proteínas de Membrana Transportadoras/deficiência , Filogenia , Células Vegetais/metabolismo , Células Vegetais/efeitos da radiação , Folhas de Planta/genética , Folhas de Planta/metabolismo , Folhas de Planta/efeitos da radiação , Regiões Promotoras Genéticas , Ligação Proteica , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Transdução de Sinais , Fatores de Transcrição/metabolismo , Técnicas do Sistema de Duplo-Híbrido
17.
Plant Cell Physiol ; 59(6): 1135-1143, 2018 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-29767769

RESUMO

Light energy is essential for photosynthetic energy production and plant growth. Chloroplasts in green tissues convert energy from sunlight into chemical energy via the electron transport chain. When the level of light energy exceeds the capacity of the photosynthetic apparatus, chloroplasts undergo a process known as photoinhibition. Since photoinhibition leads to the overaccumulation of reactive oxygen species (ROS) and the spreading of cell death, plants have developed multiple systems to protect chloroplasts from strong light. Recent studies have shown that autophagy, a system that functions in eukaryotes for the intracellular degradation of cytoplasmic components, participates in the removal of damaged chloroplasts. Previous findings also demonstrated an important role for autophagy in chloroplast turnover during leaf senescence. In this review, we describe the turnover of whole chloroplasts, which occurs via a type of autophagy termed chlorophagy. We discuss a possible regulatory mechanism for the induction of chlorophagy based on current knowledge of photoinhibition, leaf senescence and mitophagy-the autophagic turnover of mitochondria in yeast and mammals.


Assuntos
Autofagia/efeitos da radiação , Cloroplastos/efeitos da radiação , Espécies Reativas de Oxigênio/metabolismo , Cloroplastos/metabolismo , Mitocôndrias/metabolismo , Mitocôndrias/efeitos da radiação , Folhas de Planta/metabolismo , Folhas de Planta/efeitos da radiação , Raios Ultravioleta
18.
Sci Rep ; 8(1): 6097, 2018 04 17.
Artigo em Inglês | MEDLINE | ID: mdl-29666396

RESUMO

Plants utilize energy from sunlight to perform photosynthesis in chloroplast, an organelle that could be damaged by solar UV radiation. The ultraviolet-B (UV-B) photoreceptor UVR8 is required for UV-B perception and signal transduction. However, little is known about how UVR8 influence chloroplast development under UV-B radiation. Here, we characterized tomato UVR8 gene (SlUVR8) and our results indicated that SlUVR8 facilitate plant acclimation to UV-B stress by orchestrating expression of the UVB-responsive genes (HY5 and CHS) and accumulating UV-absorptive compounds. In addition, we also discovered that SlUVR8 promotes fruit chloroplast development through enhancing accumulation of transcription factor GOLDEN2-LIKE2 (SlGLK2) which determines chloroplast and chlorophyll levels. Furthermore, UV-B radiation could increase expression of SlGLK2 and its target genes in fruits and leaves. SlUVR8 is required for UVB-induced SlGLK2 expression. Together, our work not only identified the conserved functions of SlUVR8 gene in response to UV-B stress, but also uncovered a novel role that SlUVR8 could boost chloroplast development by accumulating SlGLK2 proteins.


Assuntos
Regulação da Expressão Gênica de Plantas/efeitos da radiação , Lycopersicon esculentum/genética , Fotorreceptores de Plantas/genética , Proteínas de Plantas/genética , Fatores de Transcrição/genética , Raios Ultravioleta/efeitos adversos , Aclimatação , Cloroplastos/genética , Cloroplastos/metabolismo , Cloroplastos/efeitos da radiação , Frutas/genética , Frutas/crescimento & desenvolvimento , Frutas/metabolismo , Frutas/efeitos da radiação , Lycopersicon esculentum/crescimento & desenvolvimento , Lycopersicon esculentum/metabolismo , Lycopersicon esculentum/efeitos da radiação , Fotorreceptores de Plantas/metabolismo , Fotossíntese , Proteínas de Plantas/metabolismo , Fatores de Transcrição/metabolismo
19.
Plant Cell Environ ; 41(8): 1791-1805, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29499086

RESUMO

Deep-shade plants have adapted to low-light conditions by varying morphology and physiology of cells and chloroplasts, but it still remains unclear, if prolonged periods of high-light or darkness induce additional modifications in chloroplasts' anatomy and pigment patterns. We studied giant chloroplasts (bizonoplasts) of the deep-shade lycopod Selaginella erythropus in epidermal cells of mature fully developed microphylls and subjected them to prolonged darkness and high-light conditions. Chloroplast size and ultrastructure were investigated by light and electron microscopy. Physiological traits were studied by pigment analyses, photosynthetic performance of photosystem II, and formation of reactive oxygen species. Results show that (a) thylakoid patterns and shape of mature bizonoplasts vary in response to light and dark conditions. (b) Prolonged darkness induces transitory formation of prolamellar bodies, which so far have not been described in mature chloroplasts. (c) Photosynthetic activity is linked to structural responses of chloroplasts. (d) Photosystem II is less active in the upper zone of bizonoplasts and more efficient in the grana region. (e) Formation of reactive oxygen species reflects the stress level caused by high-light. We conclude that during prolonged darkness, chlorophyll persists and even increases; prolamellar bodies form de novo in mature chloroplasts; bizonoplasts have spatial heterogeneity of photosynthetic performance.


Assuntos
Cloroplastos/efeitos da radiação , Selaginellaceae/efeitos da radiação , Adaptação Fisiológica , Clorofila/metabolismo , Cloroplastos/metabolismo , Cloroplastos/fisiologia , Cloroplastos/ultraestrutura , Microscopia Eletrônica , Fotoperíodo , Fotossíntese/efeitos da radiação , Complexo de Proteína do Fotossistema II/metabolismo , Complexo de Proteína do Fotossistema II/efeitos da radiação , Espécies Reativas de Oxigênio/metabolismo , Selaginellaceae/anatomia & histologia , Selaginellaceae/metabolismo , Selaginellaceae/fisiologia , Tilacoides/metabolismo , Tilacoides/efeitos da radiação , Tilacoides/ultraestrutura
20.
Planta ; 247(6): 1293-1306, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29460179

RESUMO

MAIN CONCLUSION: The macroalga Bryopsis corticulans relies on a sustained protective NPQ and a peculiar body architecture to efficiently adapt to the extreme light changes of intertidal shores. During low tides, intertidal algae experience prolonged high light stress. Efficient dissipation of excess light energy, measured as non-photochemical quenching (NPQ) of chlorophyll fluorescence, is therefore required to avoid photodamage. Light-harvesting regulation was studied in the intertidal macroalga Bryopsis corticulans, during high light and air exposure. Photosynthetic capacity and NPQ kinetics were assessed in different filament layers of the algal tufts and in intact chloroplasts to unravel the nature of NPQ in this siphonous green alga. We found that the morphology and pigment composition of the B. corticulans body provides functional segregation between surface sunlit filaments (protective state) and those that are underneath and undergo severe light attenuation (light-harvesting state). In the surface filaments, very high and sustained NPQ gradually formed. NPQ induction was triggered by the formation of transthylakoid proton gradient and independent of the xanthophyll cycle. PsbS and LHCSR proteins seem not to be active in the NPQ mechanism activated by this alga. Our results show that B. corticulans endures excess light energy pressure through a sustained protective NPQ, not related to photodamage, as revealed by the unusually quick restoration of photosystem II (PSII) function in the dark. This might suggest either the occurrence of transient PSII photoinactivation or a fast rate of PSII repair cycle.


Assuntos
Clorófitas/anatomia & histologia , Clorófitas/fisiologia , Oxigênio/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Clorofila/metabolismo , Clorófitas/citologia , Cloroplastos/fisiologia , Cloroplastos/efeitos da radiação , Cinética , Luz , Complexos de Proteínas Captadores de Luz/metabolismo , Complexos de Proteínas Captadores de Luz/efeitos da radiação , Fotossíntese/efeitos da radiação , Complexo de Proteína do Fotossistema II/efeitos da radiação , Alga Marinha , Estresse Fisiológico , Ondas de Maré
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