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1.
BMC Plant Biol ; 19(1): 350, 2019 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-31409298

RESUMO

BACKGROUND: The pentatricopeptide repeat (PPR) gene family, which contains multiple 35-amino acid repeats, constitutes one of the largest gene families in plants. PPR proteins function in organelles to target specific transcripts and are involved in plant development and growth. However, the function of PPR proteins in cotton is still unknown. RESULTS: In this study, we characterized a PPR gene YELLOW-GREEN LEAF (GhYGL1d) that is required for cotton plastid development. The GhYGL1d gene has a DYW domain in C-terminal and is highly express in leaves, localized to the chloroplast fractions. GhYGL1d share high amino acid-sequence homology with AtECB2. In atecb2 mutant, overexpression of GhYGL1d rescued the seedling lethal phenotype and restored the editing of accD and ndhF transcripts. Silencing of GhYGL1d led to the reduction of chlorophyll and phenotypically yellow-green leaves in cotton. Compared with wild type, GhYGL1d-silenced cotton showed significant deformations of thylakoid structures. Furthermore, the transcription levels of plastid-encoded polymerase (PEP) and nuclear-encoded polymerase (NEP) dependent genes were decreased in GhYGL1d-silenced cotton. CONCLUSIONS: Our data indicate that GhYGL1d not only contributes to the editing of accD and ndhF genes, but also affects the expression of NEP- and PEP-dependent genes to regulate the development of thylakoids, and therefore regulates leaf variegation in cotton.


Assuntos
Cloroplastos/genética , Gossypium/genética , Proteínas de Plantas/fisiologia , Cloroplastos/metabolismo , Cloroplastos/fisiologia , Gossypium/anatomia & histologia , Gossypium/metabolismo , Folhas de Planta/anatomia & histologia , Folhas de Planta/genética , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo
2.
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
3.
Plant Sci ; 286: 78-88, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31300145

RESUMO

Chloroplastic Cpn60 proteins are type I chaperonins comprising of Cpn60α and Cpn60ß subunits. Arabidopsis genome contains six entries in Cpn60 family, out of which two are for Cpn60α subunit and four for Cpn60ß subunit. We noted that the cpn60ß4 knockout mutant plants (T-DNA insertion salk_064887 line) differed from the wild type Col-0 plants in the developmental programming. cpn60ß4 mutant plants showed early seed germination. Radical emergence, hypocotyl emergence and cotyledons opening were faster in cpn60ß4 mutant plants than WT. Importantly, cpn60ß4 mutant plants showed early-flowering phenotype. The number of flowers and siliques as well as weight of the seeds were higher in cpn60ß4 mutant plants as compared to Col-0 plants. These effects were reverted to wild type like growth and developmental patterns when genomic fragment of Arabidopsis encompassing Cpn60ß4 gene was complemented in the mutant background. The overexpression of Cpn60ß4 gene using CaMV35 promoter in wild type background (OE-Cpn60ß4) delayed the floral transition as against wild type plants. The plastid division were affected in cpn60ß4 mutant plants compared to Col-0. The results of this study suggest that Cpn60ß4 plays important role(s) in chloroplast development and is a key factor in plant growth, development and flowering in Arabidopsis.


Assuntos
Arabidopsis/genética , Flores/crescimento & desenvolvimento , Regulação da Expressão Gênica de Plantas , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Cloroplastos/metabolismo , Flores/genética , Regulação da Expressão Gênica no Desenvolvimento , Reprodução
4.
J Agric Food Chem ; 67(32): 8746-8755, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31322881

RESUMO

The underlying mechanisms of the higher photosynthetic efficiency of cultivated cassava relative to its wild species are poorly understood. In the present study, proteins in leaves and chloroplasts were analyzed to compare the differences among the cultivar SC205, its wild ancestor W14, and the related species Glaziovii. The functions of differential proteins are associated with 10 ontology groups including photosynthesis, carbohydrate and energy metabolism, as well as potential signal pathway. The protein-protein networks among 41 differential proteins showed that PGK1 is a hub protein and protein cross-interactions affected the differentiation of photosynthetic rate. Anatomy patterns and PEPC detection suggested that SC205 has more C4 photosynthesis characteristics than Glaziovii and W14. Finally, a mechanism model of the efficient photosynthesis was proposed based on the remarkable variations in photosynthetic parameters and protein functions in the domestic cultivars.


Assuntos
Manihot/metabolismo , Fotossíntese , Cloroplastos/metabolismo , Manihot/classificação , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo , Ligação Proteica , Mapas de Interação de Proteínas
5.
BMC Plant Biol ; 19(1): 262, 2019 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-31208336

RESUMO

BACKGROUND: Stored potato (Solanum tuberosum L.) tubers are sensitive to wet conditions that can cause rotting in long-term storage. To study the effect of water on the tuber surface during storage, microarray analysis, RNA-Seq profiling, qRT-PCR and phytohormone measurements were performed to study gene expression and hormone content in wet tubers incubated at two temperatures: 4 °C and 15 °C. The growth of the plants was also observed in a greenhouse after the incubation of tubers in wet conditions. RESULTS: Wet conditions induced a low-oxygen response, suggesting reduced oxygen availability in wet tubers at both temperatures when compared to that in the corresponding dry samples. Wet conditions induced genes coding for heat shock proteins, as well as proteins involved in fermentative energy production and defense against reactive oxygen species (ROS), which are transcripts that have been previously associated with low-oxygen stress in hypoxic or anoxic conditions. Wet treatment also induced senescence-related gene expression and genes involved in cell wall loosening, but downregulated genes encoding protease inhibitors and proteins involved in chloroplast functions and in the biosynthesis of secondary metabolites. Many genes involved in the production of phytohormones and signaling were also affected by wet conditions, suggesting altered regulation of growth by wet conditions. Hormone measurements after incubation showed increased salicylic acid (SA), abscisic acid (ABA) and auxin (IAA) concentrations as well as reduced production of jasmonate 12-oxo-phytodienoic acid (OPDA) in wet tubers. After incubation in wet conditions, the tubers produced fewer stems and more roots compared to controls incubated in dry conditions. CONCLUSIONS: In wet conditions, tubers invest in ROS protection and defense against the abiotic stress caused by reduced oxygen due to excessive water. Changes in ABA, SA and IAA that are antagonistic to jasmonates affect growth and defenses, causing induction of root growth and rendering tubers susceptible to necrotrophic pathogens. Water on the tuber surface may function as a signal for growth, similar to germination of seeds.


Assuntos
Armazenamento de Alimentos , Reguladores de Crescimento de Planta/metabolismo , Tubérculos/metabolismo , Solanum tuberosum/metabolismo , Metabolismo dos Carboidratos , Parede Celular/metabolismo , Cloroplastos/metabolismo , Regulação da Expressão Gênica de Plantas , Análise de Sequência com Séries de Oligonucleotídeos , Estresse Oxidativo , Tubérculos/crescimento & desenvolvimento , Metabolismo Secundário , Solanum tuberosum/crescimento & desenvolvimento , Transcriptoma , Água
6.
J Agric Food Chem ; 67(26): 7249-7257, 2019 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-31244201

RESUMO

The duration of the rice growth phase has always been an important target trait. The identification of mutations in rice that alter these processes and result in a shorter growth phase could have potential benefits for crop production. In this study, we isolated an early aging rice mutant, pe-1, with light green leaves, using γ-mutated indica rice cultivar and subsequent screening methods, which is known as the phytochrome synthesis factor Se5 that controls rice flowering. The pe-1 plant is accompanied by a decreased chlorophyll content, an enhanced photosynthesis, and a decreased pollen fertility. PE-1, a close homologue of HY1, is localized in the chloroplast. Expression pattern analysis indicated that PE-1 was mainly expressed in roots, stems, leaves, leaf sheaths, and young panicles. The knockout of PE-1 using the CRISPR/Cas9 system decreased the chlorophyll content and downregulated the expression of PE-1-related genes. Furthermore, the chloroplasts of pe-1 were filled with many large-sized starch grains, and the number of osmiophilic granules (a chloroplast lipid reservoir) was significantly decreased. Altogether, our findings suggest that PE-1 functions as a master regulator to mediate in chlorophyll biosynthesis and photosynthetic pathways.


Assuntos
Cloroplastos/metabolismo , Heme Oxigenase-1/metabolismo , Oryza/enzimologia , Oryza/crescimento & desenvolvimento , Proteínas de Plantas/metabolismo , Clorofila/metabolismo , Cloroplastos/genética , Regulação da Expressão Gênica de Plantas , Heme Oxigenase-1/genética , Mutação , Oryza/genética , Oryza/metabolismo , Fotossíntese , Proteínas de Plantas/genética
7.
Nat Commun ; 10(1): 2630, 2019 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-31201314

RESUMO

Phytochromes initiate chloroplast biogenesis by activating genes encoding the photosynthetic apparatus, including photosynthesis-associated plastid-encoded genes (PhAPGs). PhAPGs are transcribed by a bacterial-type RNA polymerase (PEP), but how phytochromes in the nucleus activate chloroplast gene expression remains enigmatic. We report here a forward genetic screen in Arabidopsis that identified NUCLEAR CONTROL OF PEP ACTIVITY (NCP) as a necessary component of phytochrome signaling for PhAPG activation. NCP is dual-targeted to plastids and the nucleus. While nuclear NCP mediates the degradation of two repressors of chloroplast biogenesis, PIF1 and PIF3, NCP in plastids promotes the assembly of the PEP complex for PhAPG transcription. NCP and its paralog RCB are non-catalytic thioredoxin-like proteins that diverged in seed plants to adopt nonredundant functions in phytochrome signaling. These results support a model in which phytochromes control PhAPG expression through light-dependent double nuclear and plastidial switches that are linked by evolutionarily conserved and dual-localized regulatory proteins.


Assuntos
Proteínas de Arabidopsis/metabolismo , Cloroplastos/metabolismo , Chaperonas Moleculares/metabolismo , Fitocromo/metabolismo , Transcrição Genética/fisiologia , Arabidopsis/fisiologia , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Núcleo Celular/genética , Núcleo Celular/metabolismo , Cloroplastos/genética , RNA Polimerases Dirigidas por DNA/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Luz , Fotossíntese/fisiologia , Plantas Geneticamente Modificadas , Plastídeos/genética , Plastídeos/metabolismo , Transdução de Sinais/fisiologia , Transcrição Genética/efeitos da radiação
8.
Nat Commun ; 10(1): 2629, 2019 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-31201355

RESUMO

Light initiates chloroplast biogenesis by activating photosynthesis-associated genes encoded by not only the nuclear but also the plastidial genome, but how photoreceptors control plastidial gene expression remains enigmatic. Here we show that the photoactivation of phytochromes triggers the expression of photosynthesis-associated plastid-encoded genes (PhAPGs) by stimulating the assembly of the bacterial-type plastidial RNA polymerase (PEP) into a 1000-kDa complex. Using forward genetic approaches, we identified REGULATOR OF CHLOROPLAST BIOGENESIS (RCB) as a dual-targeted nuclear/plastidial phytochrome signaling component required for PEP assembly. Surprisingly, RCB controls PhAPG expression primarily from the nucleus by interacting with phytochromes and promoting their localization to photobodies for the degradation of the transcriptional regulators PIF1 and PIF3. RCB-dependent PIF degradation in the nucleus signals the plastids for PEP assembly and PhAPG expression. Thus, our findings reveal the framework of a nucleus-to-plastid anterograde signaling pathway by which phytochrome signaling in the nucleus controls plastidial transcription.


Assuntos
Proteínas de Arabidopsis/metabolismo , Cloroplastos/metabolismo , RNA Polimerases Dirigidas por DNA/metabolismo , Fitocromo/metabolismo , Tiorredoxinas/metabolismo , Transcrição Genética/fisiologia , Arabidopsis/fisiologia , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Núcleo Celular/metabolismo , Cloroplastos/genética , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Luz , Fotossíntese/fisiologia , Plantas Geneticamente Modificadas , Plastídeos/genética , Plastídeos/metabolismo , Proteólise , Transdução de Sinais/fisiologia , Transcrição Genética/efeitos da radiação
9.
BMC Plant Biol ; 19(1): 244, 2019 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-31174473

RESUMO

BACKGROUND: Even though the roles of pentatricopeptide repeat (PPR) proteins are essential in plant organelles, the function of many chloroplast-targeted PPR proteins remains unknown. Here, we characterized the function of a chloroplast-localized PPR protein (At3g59040), which is classified as the 287th PPR protein among the 450 PPR proteins in Arabidopsis ( http://ppr.plantenergy.uwa.edu.au ). RESULTS: The homozygous ppr287 mutant with the T-DNA inserted into the last exon displayed pale-green and yellowish phenotypes. The microRNA-mediated knockdown mutants were generated to further confirm the developmental defect phenotypes of ppr287 mutants. All mutants had yellowish leaves, shorter roots and height, and less seed yield, indicating that PPR287 is crucial for normal Arabidopsis growth and development. The photosynthetic activity and chlorophyll content of ppr287 mutants were markedly reduced, and the chloroplast structures of the mutants were abnormal. The levels of chloroplast rRNAs were decreased in ppr287 mutants. CONCLUSIONS: These results suggest that PPR287 plays an essential role in chloroplast biogenesis and function, which is crucial for the normal growth and development of Arabidopsis.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Proteínas de Cloroplastos/genética , Cloroplastos/metabolismo , Regulação da Expressão Gênica de Plantas , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Proteínas de Cloroplastos/metabolismo , RNA de Cloroplastos/genética , RNA de Cloroplastos/metabolismo
10.
Plant Physiol Biochem ; 141: 353-369, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31207496

RESUMO

Reactive oxygen species (ROS) - the byproducts of aerobic metabolism - influence numerous aspects of the plant life cycle and environmental response mechanisms. In plants, ROS act like a double-edged sword; they play multiple beneficial roles at low concentrations, whereas at high concentrations ROS and related redox-active compounds cause cellular damage through oxidative stress. To examine the dual role of ROS as harmful oxidants and/or crucial cellular signals, this review elaborates that (i) how plants sense and respond to ROS in various subcellular organelles and (ii) the dynamics of subsequent ROS-induced signaling processes. The recent understanding of crosstalk between various cellular compartments in mediating their redox state spatially and temporally is discussed. Emphasis on the beneficial effects of ROS in maintaining cellular energy homeostasis, regulating diverse cellular functions, and activating acclimation responses in plants exposed to abiotic and biotic stresses are described. The comprehensive view of cellular ROS dynamics covering the breadth and versatility of ROS will contribute to understanding the complexity of apparently contradictory ROS roles in plant physiological responses in less than optimum environments.


Assuntos
Oxirredução , Estresse Oxidativo , Fenômenos Fisiológicos Vegetais , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais , Estresse Fisiológico , Aclimatação , Antioxidantes/metabolismo , Arabidopsis/metabolismo , Núcleo Celular/metabolismo , Cloroplastos/metabolismo , Citosol/metabolismo , Regulação da Expressão Gênica , Genes de Plantas , Mitocôndrias/metabolismo , Oryza/metabolismo , Oxigênio/metabolismo , Peroxissomos/metabolismo , Fotossíntese , Populus/metabolismo
11.
Plant Physiol Biochem ; 141: 456-465, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31247428

RESUMO

Alfalfa (Medicago sativa L.) is an important perennial legume and used as a forage crop worldwide, and has extensive resistance to various abiotic stresses. Nitric oxide (NO) plays a critical role in response to external and internal cues to regulate plant growth and development. However, endogenous NO-mediated molecular mechanisms of drought tolerance in alfalfa is poorly understood. To get a deeper insight into the regulate pathway of NO, RNA-Seq was used to profile transcriptome changes of alfalfa seedlings, which were treated with NO scavenger under normal and drought conditions. A total of 1,025 and 3,461 differently-expressed genes (FDR < 0.0001; fold change ≥ 2) were observed while NO absence under normal and drought conditions, respectively. Based on GO enrich and KEGG pathway analysis, we found NO absence induced photosynthesis, carbon fixation in photosynthetic organisms and primary metabolism were significantly up-enriched. Most oxidoreductase, dehydrogenase, reductase and transferase genes were down-regulated in the above processes. Moreover, NO absence restrained chlorophyll biosynthesis and decreased different sugar content. Therefore, this work provides insights into the mechanism that NO-mediated enhanced photosynthesis and carbohydrate metabolism in alfalfa under drought stress.


Assuntos
Metabolismo dos Carboidratos , Secas , Medicago sativa/enzimologia , Medicago sativa/fisiologia , Óxido Nítrico/química , Fotossíntese , Parede Celular/metabolismo , Clorofila/química , Cloroplastos/metabolismo , Perfilação da Expressão Gênica , Biblioteca Gênica , Plântula/enzimologia , Plântula/fisiologia , Análise de Sequência de RNA , Amido/química , Estresse Fisiológico , Sacarose/química
12.
Food Chem ; 297: 124964, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31253313

RESUMO

Broccoli undergoes yellowing in unfavorable conditions, thereby diminishing the sensory quality and commodity value. This study aimed to investigate systematically cellular and/or biomolecular changes involved in broccoli yellowing by analyzing changes in microstructural integrity, pigment content, and gene expression. On day-5 of storage at 20 °C, the buds turned yellow without blooming and showed structural damage; ultrastructural analysis revealed plastid transformation and abnormal chloroplast development. Genes regulating pigment content and chloroplast structure directly were identified. More specifically, BoCAO and BoNYC1 regulated chlorophyll turnover, affecting chlorophyll a and b contents. Changes in the ß-cryptoxanthin content were influenced by the combined action of up- (BoHYD) and downstream (BoZEP) genes. BoZEP and BoVDE were activated after cold-temperature induction. High BoHO1 expression delayed yellowing at low temperature, inducing BoZEP expression. Color intensity correlated significantly with the chlorophyll b, ß-cryptoxanthin, and ß-carotene contents, which were associated with increased yellowing of plant tissues.


Assuntos
Brassica/fisiologia , Carotenoides/metabolismo , Clorofila/metabolismo , Armazenamento de Alimentos , beta-Criptoxantina/genética , beta-Criptoxantina/metabolismo , Vias Biossintéticas , Brassica/ultraestrutura , Cloroplastos/metabolismo , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plastídeos/genética , Plastídeos/metabolismo , Temperatura Ambiente
13.
Plant Sci ; 285: 230-238, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31203888

RESUMO

In higher plants, Fibrillins (FBNs) constitute a conserved plastid-lipid-associated (PAPs) protein family and modulate the metabolite transport and lipid metabolism in plastids of dicot species. However, FBNs have not functionally characterized in monocot species. In this study, the function of rice fibrillin 1 (OsFBN1) was investigated. The subcellular localization assay showed that the N-terminal chloroplast transport peptide (CTP) could facilitate the import of OsFBN1 into chloroplast. OsFBN1 specifically bound C18- and C20- fatty acids in vitro. Overexpressing OsFBN1 increased the tiller number but decreased the panicle length, grain-filling percent and JA levels compared to the wild type and RNAi silencing lines under heat stress. In addition, the overexpressing lines had more plastoglobules (PGs) than the wild type and RNAi silencing lines under both normal and heat stress conditions. Moreover, overexpressing OsFBN1 affected the transcription levels of OsAOS2 in JA synthesis, OsTHF1, OsABC1K7 and OsPsaE in thylakoid stability and photosynthesis, OsABC1-4 and OsSPS2 in ubiquinone-metabolism, OsHDR, OsDXR, and OsFPPS in isoprenoid metabolism. Collectively, these findings suggest the essential role of rice OsFBN1 in PG formation and lipid metabolism in chloroplasts, which coordinately regulate the growth and grain filling of the overexpressing lines under heat stress.


Assuntos
Cloroplastos/metabolismo , Ciclopentanos/metabolismo , Grão Comestível/metabolismo , Oryza/metabolismo , Oxilipinas/metabolismo , Proteínas de Plantas/metabolismo , Cloroplastos/ultraestrutura , Grão Comestível/crescimento & desenvolvimento , Resposta ao Choque Térmico , Metabolismo dos Lipídeos , Lipoproteínas/metabolismo , Microscopia Eletrônica de Transmissão , Oryza/genética , Oryza/fisiologia , Oryza/ultraestrutura , Fotossíntese , Proteínas de Plantas/fisiologia , Plantas Geneticamente Modificadas , Reação em Cadeia da Polimerase em Tempo Real , Tilacoides/metabolismo
14.
Plant Physiol Biochem ; 141: 154-163, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31163342

RESUMO

Different nitrogen (N) sources have been reported to significantly affect the photosynthesis (Pn) and its attributes. However, molybdenum (Mo) induced effects on photosynthetic efficacy of winter wheat under different N sources have not been investigated. A hydroponic study was carried out comprising of two winter wheat cultivars '97003' and '97014' as Mo-efficient and Mo-inefficient, respectively to underpin the effects of Mo supply (0 and 1 µM) on photosynthetic efficacy of winter wheat under different N sources (NO3̶, NH4NO3 or NH4+). The results revealed that Mo-induced increases in dry weight, gas exchange parameters, chlorophyll contents, NR activities, NO3̶ assimilation, total N contents and transcripts of TaNR and TaNRT1.1 genes under different N sources followed the trend of NH4NO3 > NO3̶ > NH4+, suggesting that Mo has more complementary effects to nitrate nutrition than sole ammonium. Interestingly, under Mo-deprivation environments, cultivar '97003' recorded more pronounced alterations in Mo-dependent parameters than '97014' cultivar. Moreover, Mo application significantly improved the chlorophyll contents and chloroplast configuration in all N sources showing that Mo has a key role in chlorophyll biosynthesis and chloroplast integrity. The results also highlighted that Mo-induced enhancements in total N contents and photosynthetic characteristics followed the same order as NH4NO3 > NO3- > NH4+, suggesting that Mo might affect Pn through N metabolism. In crux, our study findings imply that Mo supply increased Pn not only through chlorophyll synthesis and chloroplast configuration but also by N uptake and assimilation which may represent a strategy of Mo fertilizer to strengthen the photosynthetic machinery.


Assuntos
Compostos de Amônio/metabolismo , Molibdênio/farmacologia , Nitrogênio/metabolismo , Fotossíntese/efeitos dos fármacos , Triticum/fisiologia , Clorofila/metabolismo , Cloroplastos/metabolismo , Fertilizantes , Hidroponia , Microscopia Eletrônica de Transmissão , Nitratos/metabolismo , Proteínas de Plantas/metabolismo , Triticum/efeitos dos fármacos
15.
Nat Plants ; 5(6): 581-588, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31182842

RESUMO

Chloroplasts are integral to sensing biotic and abiotic stress in plants, but their role in transducing Ca2+-mediated stress signals remains poorly understood1,2. Here we identify cMCU, a member of the mitochondrial calcium uniporter (MCU) family, as an ion channel mediating Ca2+ flux into chloroplasts in vivo. Using a toolkit of aequorin reporters targeted to chloroplast stroma and the cytosol in cMCU wild-type and knockout lines, we provide evidence that stress-stimulus-specific Ca2+ dynamics in the chloroplast stroma correlate with expression of the channel. Fast downstream signalling events triggered by osmotic stress, involving activation of the mitogen-activated protein kinases (MAPK) MAPK3 and MAPK6, and the transcription factors MYB60 and ethylene-response factor 6 (ERF6), are influenced by cMCU activity. Relative to wild-type plants, cMCU knockouts display increased resistance to long-term water deficit and improved recovery on rewatering. Modulation of stromal Ca2+ in specific processing of stress signals identifies cMCU as a component of plant environmental sensing.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Canais de Cálcio/metabolismo , Cloroplastos/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Cálcio/metabolismo , Canais de Cálcio/genética , Cloroplastos/genética , Escherichia coli , Técnicas de Inativação de Genes , Sistema de Sinalização das MAP Quinases , Pressão Osmótica
16.
Plant Sci ; 284: 185-191, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31084871

RESUMO

Transcriptional activation of ascorbate biosynthesis-associated genes under illumination is one of the important steps in ascorbate pool size regulation in photosynthetic tissues. Several biological processes within chloroplasts such as photosynthesis are required for this activation, suggesting functional chloroplasts to play a key role. We herein found that when grown on agar plate, ascorbate content in Arabidopsis non-photosynthetic tissues, roots, are unexpectedly almost comparable to that in shoots. The high accumulation of ascorbate was particularly observed in root regions closer to the root-hypocotyl junction, in which chloroplast development occurred because of a direct exposure to light. When chloroplast development in roots were further stimulated by shoot removal, the expression of biosynthetic genes, especially VTC2 gene that encodes GDP-l-galactose phosphorylase, was activated, resulting in an increase in ascorbate pool size. These positive effects were canceled when the roots were treated with a photosynthetic inhibitor. A null mutation in the LONG HYPOCOTYL 5 (HY5) gene almost completely inhibited root greening as well as the VTC2 expression. Overall, these findings show that chloroplast development can trigger the expression of ascorbate biosynthesis-associated genes not only in leaves but also in roots.


Assuntos
Arabidopsis/metabolismo , Ácido Ascórbico/biossíntese , Cloroplastos/fisiologia , Raízes de Plantas/metabolismo , Arabidopsis/fisiologia , Ácido Ascórbico/metabolismo , Clorofila/metabolismo , Cloroplastos/metabolismo , Regulação da Expressão Gênica de Plantas , Genes de Plantas/fisiologia , Redes e Vias Metabólicas , Raízes de Plantas/fisiologia , Reação em Cadeia da Polimerase em Tempo Real
17.
Nat Plants ; 5(5): 525-538, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-31061535

RESUMO

Communication between organelles and the nucleus is essential for fitness and survival. Retrograde signals are cues emitted from the organelles to regulate nuclear gene expression. GENOMES UNCOUPLED1 (GUN1), a protein of unknown function, has emerged as a central integrator, participating in multiple retrograde signalling pathways that collectively regulate the nuclear transcriptome. Here, we show that GUN1 regulates chloroplast protein import through interaction with the import-related chaperone cpHSC70-1. We demonstrated that overaccumulation of unimported precursor proteins (preproteins) in the cytosol causes a GUN phenotype in the wild-type background and enhances the GUN phenotype of the gun1 mutant. Furthermore, we identified the cytosolic HSP90 chaperone complex, induced by overaccumulated preproteins, as a central regulator of photosynthetic gene expression that determines the expression of the GUN phenotype. Taken together, our results suggest a model in which protein import capacity, folding stress and the cytosolic HSP90 complex control retrograde communication.


Assuntos
Proteínas de Arabidopsis/fisiologia , Proteínas de Ligação a DNA/fisiologia , Arabidopsis/metabolismo , Arabidopsis/fisiologia , Proteínas de Arabidopsis/metabolismo , Cloroplastos/metabolismo , Citosol/metabolismo , Proteínas de Ligação a DNA/metabolismo , Proteínas de Choque Térmico HSC70/metabolismo , Proteínas de Choque Térmico HSP90/metabolismo , Transdução de Sinais/fisiologia , Transcriptoma
18.
Environ Pollut ; 248: 1020-1027, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31091634

RESUMO

Microsorum pteropus is a novel potential Cd (cadmium) aquatic hyperaccumulator. In the present study, hydroponic experiments were conducted to assess the accumulation and subcellular distribution of Cd in the root, stem and leaf of M. pteropus. SEM (scanning electron microscopy) - EDX (energy dispersive X-ray fluorescence spectrometer) and TEM (transmission electron microscopy) were used to observe the ultrastructure of different tissues under 500 µM Cd exposure. After exposure to 500 µM Cd for 7 days, the root, stem and leaf of M. pteropus can accumulate to be > 400 mg/kg Cd in dry mass with no significant influence on the growth. In the root and leaf of M. pteropus, the Cd was more likely to store in the cell wall fraction. However, Cd in the stem was mainly stored in both the cell wall fraction and the cytoplasm fraction. Under SEM observation and EDX detection, 1) Cd was found to be sequestrated in the epidermis or chelated in the root cells, 2) no significant deposit spots were observed in the stem, 3) Cd was found in the trichome of the leaf, and the sporangium was not damaged. TEM observations revealed 1) possible Cd precipitations in the root cell and 2) no significant ultrastructure variation in the stem, and 3) the chloroplast retained its structure and was not affected by the Cd. M. pteropus showed great capacity for Cd accumulation without influencing growth. In addition, the ultrastructure of all the tissues was not damaged by the Cd. M. pteropus showed a great potential in phytoremediation in heavy metal polluted water solutions, and may provide new directions for the study of resistance mechanisms of aquatic hyperaccumulators.


Assuntos
Biodegradação Ambiental , Cádmio/análise , Folhas de Planta/química , Raízes de Plantas/química , Caules de Planta/química , Polypodiaceae/metabolismo , Poluentes do Solo/análise , Cloroplastos/metabolismo , Hidroponia , Folhas de Planta/crescimento & desenvolvimento , Raízes de Plantas/crescimento & desenvolvimento , Caules de Planta/crescimento & desenvolvimento
19.
Plant Cell Rep ; 38(7): 803-818, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31079194

RESUMO

Plant cells are characterized by a unique group of interconvertible organelles called plastids, which are descended from prokaryotic endosymbionts. The most studied plastid type is the chloroplast, which carries out the ancestral plastid function of photosynthesis. During the course of evolution, plastid activities were increasingly integrated with cellular metabolism and functions, and plant developmental processes, and this led to the creation of new types of non-photosynthetic plastids. These include the chromoplast, a carotenoid-rich organelle typically found in flowers and fruits. Here, we provide an introduction to non-photosynthetic plastids, and then review the structures and functions of chromoplasts in detail. The role of chromoplast differentiation in fruit ripening in particular is explored, and the factors that govern plastid development are examined, including hormonal regulation, gene expression, and plastid protein import. In the latter process, nucleus-encoded preproteins must pass through two successive protein translocons in the outer and inner envelope membranes of the plastid; these are known as TOC and TIC (translocon at the outer/inner chloroplast envelope), respectively. The discovery of SP1 (suppressor of ppi1 locus1), which encodes a RING-type ubiquitin E3 ligase localized in the plastid outer envelope membrane, revealed that plastid protein import is regulated through the selective targeting of TOC complexes for degradation by the ubiquitin-proteasome system. This suggests the possibility of engineering plastid protein import in novel crop improvement strategies.


Assuntos
Cloroplastos/metabolismo , Plastídeos/metabolismo , Proteínas de Cloroplastos/genética , Proteínas de Cloroplastos/metabolismo , Cloroplastos/genética , Organelas/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plasmídeos/genética , Plastídeos/genética , Transporte Proteico
20.
Plant Cell Rep ; 38(7): 825-833, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31139894

RESUMO

Recently, plants have emerged as a lucrative alternative system for the production of recombinant proteins, as recombinant proteins produced in plants are safer and cheaper than those produced in bacteria and animal cell-based production systems. To obtain high yields in plants, recombinant proteins are produced in chloroplasts using different strategies. The first strategy is based on chloroplast transformation, followed by gene expression and translation in chloroplasts. This has proven to be a powerful approach for the production of proteins at high levels. The second approach is based on nuclear transformation, followed by post-translational import of proteins from the cytosol into chloroplasts. In the nuclear transformation approach, foreign genes are stably integrated into the nuclear genome or transiently expressed in the nucleus by non-integrating T-DNA. Although this approach also has great potential for protein production at high levels, it has not been thoroughly investigated. In this review, we focus on nuclear transformation-based protein expression and its subsequent sequestration in chloroplasts, and summarize the different strategies used for high-level production of recombinant proteins. We also discuss future directions for further improvements in protein production in chloroplasts through nuclear transformation-based gene expression.


Assuntos
Núcleo Celular/metabolismo , Cloroplastos/metabolismo , Cloroplastos/genética , Transporte Proteico/genética , Transporte Proteico/fisiologia , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Transformação Genética/genética
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