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1.
Int J Mol Sci ; 20(19)2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31574927

RESUMO

Leaf variegation has been demonstrated to have adaptive functions such as cold tolerance. Pittosporum tobira is an ornamental plant with natural leaf variegated cultivars grown in temperate regions. Herein, we investigated the role of leaf variegation in low temperature responses by comparing variegated "Variegatum" and non-variegated "Green Pittosporum" cultivars. We found that leaf variegation is associated with impaired chloroplast development in the yellow sector, reduced chlorophyll content, strong accumulation of carotenoids and high levels of ROS. However, the photosynthetic efficiency was not obviously impaired in the variegated leaves. Also, leaf variegation plays low temperature protective function since "Variegatum" displayed strong and efficient ROS-scavenging enzymatic systems to buffer cold (10 °C)-induced damages. Transcriptome analysis under cold conditions revealed 309 differentially expressed genes between both cultivars. Distinctly, the strong cold response observed in "Variegatum" was essentially attributed to the up-regulation of HSP70/90 genes involved in cellular homeostasis; up-regulation of POD genes responsible for cell detoxification and up-regulation of FAD2 genes and subsequent down-regulation of GDSL genes leading to high accumulation of polyunsaturated fatty acids for cell membrane fluidity. Overall, our results indicated that leaf variegation is associated with changes in physiological, biochemical and molecular components playing low temperature protective function in P. tobira.


Assuntos
Adaptação Biológica , Temperatura Baixa , Folhas de Planta/fisiologia , Rosales/fisiologia , Cloroplastos/genética , Cloroplastos/metabolismo , Cloroplastos/ultraestrutura , Biologia Computacional/métodos , Metabolismo Energético , Perfilação da Expressão Gênica , Regulação Enzimológica da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Sequenciamento de Nucleotídeos em Larga Escala , Anotação de Sequência Molecular , Fenótipo , Fotossíntese , Espécies Reativas de Oxigênio/metabolismo
2.
J Plant Physiol ; 243: 153048, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31639536

RESUMO

Investigations of the luminal immunophilin AtCYP38 (cyclophilin 38) in Arabidopsis thaliana (At), the orthologue of the complex immunophilin TLP40 from Spinacia oleracea, revealed its involvement in photosystem II (PSII) repair and assembly, biogenesis of PSII complex, and cellular signalling. However, the main physiological roles of AtCYP38 and TLP40 are related to regulation of thylakoid PP2A-type phosphatase involved in PSII core protein dephosphorylation, and chaperone function during protein folding. Here we further investigate physiological roles of AtCYP38 and analyse the ultrastructure of chloroplasts from cyp38-2 plants. Transmission electron microscopy followed by quantitative micrography revealed modifications in thylakoid stacking. We also confirm that the depletion of AtCYP38 influences PSII performance, which leads to stunted phenotype of cyp38-2 plants.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Ciclofilinas/genética , Complexo de Proteína do Fotossistema II/metabolismo , Tilacoides/metabolismo , Arabidopsis/enzimologia , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Cloroplastos/ultraestrutura , Ciclofilinas/metabolismo , Microscopia Eletrônica de Transmissão
3.
Chemosphere ; 235: 1066-1072, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31561296

RESUMO

This study was conducted to explore the effects of priming of seven-year-old aged seeds with different concentrations of silver nanoparticles (AgNPs) on growth of broad bean (Vicia faba L.). Seeds were primed with different concentrations of AgNPs for 6 h before growing in the plastic trays. Different growth parameters like growth attributes, photosynthetic pigments, carbohydrates, antioxidant enzymes and chloroplast ultrastructure were estimated after 14 days of germination. Priming with AgNPs affected the root and shoot growth attributes as compared with control depending upon concentrations of AgNPs. In all treatments, photosynthetic pigments increased significantly above control levels, but total soluble sugars decreased in 10 and 50 ppm AgNPs and slightly increased in 100 ppm AgNPs as compared with control. Starch accumulation was apparent in all treated seedlings above that of control levels. Mesophyll cells of all treated seedlings were altered with electron dense particles than control. Priming with AgNPs affected the chloroplast structure which appeared in the form of less stacking of Greene, formation of protrusions and extensions, irregular shape of chloroplasts as compared with spindle shaped regular chloroplasts of control. In all treatments, total phenols were slightly affected as compared with control. The antioxidant enzyme activities in seedlings varied with the dose and type of antioxidants. Overall, AgNPs adversely affected the chloroplast ultrastructure, but increased growth of seedlings and starch accumulation. Further studies are required to explore the effects of AgNPs on the long-term on crop productivity of aged seeds.


Assuntos
Cloroplastos/efeitos dos fármacos , Nanopartículas Metálicas/química , Plântula/ultraestrutura , Prata/química , Antioxidantes/farmacologia , Cloroplastos/ultraestrutura , Germinação/efeitos dos fármacos , Fotossíntese , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Sementes/efeitos dos fármacos , Prata/farmacologia , Amido/metabolismo , Vicia faba/crescimento & desenvolvimento , Vicia faba/ultraestrutura
4.
Int J Mol Sci ; 20(17)2019 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-31470529

RESUMO

Ulmus pumila 'Jinye', the colorful leaf mutant of Ulmus pumila L., is widely used in landscaping. In common with most leaf color mutants, U. pumila 'Jinye' exhibits growth inhibition. In this study, U. pumila L. and U. pumila 'Jinye' were used to elucidate the reasons for growth inhibition at the physiological, cellular microstructural, and transcriptional levels. The results showed that the pigment (chlorophyll a, chlorophyll b, and carotenoids) content of U. pumila L. was higher than that of U. pumila 'Jinye', whereas U. pumila 'Jinye' had a higher proportion of carotenoids, which may be the cause of the yellow leaves. Examination of the cell microstructure and RNA sequencing analysis showed that the leaf color and growth inhibition were mainly due to the following reasons: first, there were differences in the structure of the thylakoid grana layer. U. pumila L. has a normal chloroplast structure and clear thylakoid grana slice layer structure, with ordered and compact thylakoids. However, U. pumila 'Jinye' exhibited the grana lamella stacking failures and fewer thylakoid grana slice layers. As the pigment carrier and the key location for photosynthesis, the close stacking of thylakoid grana could combine more chlorophyll and promote efficient electron transfer promoting the photosynthesis reaction. In addition, U. pumila 'Jinye' had a lower capacity for light energy absorption, transformation, and transportation, carbon dioxide (CO2) fixation, lipopolysaccharide biosynthesis, auxin synthesis, and protein transport. The genes related to respiration and starch consumption were higher than those of U. pumila L., which indicated less energy accumulation caused the growth inhibition of U. pumila 'Jinye'. Finally, compared with U. pumila 'Jinye', the transcription of genes related to stress resistance all showed an upward trend in U. pumila L. That is to say, U. pumila L. had a greater ability to resist adversity, which could maintain the stability of the intracellular environment and maintain normal progress of physiological metabolism. However, U. pumila 'Jinye' was more susceptible to changes in the external environment, which affected normal physiological metabolism. This study provides evidence for the main cause of growth inhibition in U. pumila 'Jinye', information for future cultivation, and information on the mutation mechanism for the breeding of colored leaf trees.


Assuntos
Cloroplastos/genética , Perfilação da Expressão Gênica/métodos , Mutação , Folhas de Planta/genética , Ulmus/genética , Carotenoides/metabolismo , Clorofila/metabolismo , Clorofila A/metabolismo , Cloroplastos/metabolismo , Cloroplastos/ultraestrutura , Cor , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Microscopia Eletrônica de Transmissão , Fotossíntese/genética , Pigmentos Biológicos/metabolismo , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Tilacoides/genética , Tilacoides/metabolismo , Tilacoides/ultraestrutura , Ulmus/crescimento & desenvolvimento , Ulmus/metabolismo
5.
Plant Sci ; 287: 110203, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31481208

RESUMO

Embryo and endosperm originate from the double fertilization, but they have different developmental fates and biological functions. We identified a previously undescribed maize seed mutant, wherein the embryo appears to be more severely affected than the endosperm (embryo-specific, emb). In the W22 background, the emb embryo arrests at the transition stage whereas its endosperm appears nearly normal in size. At maturity, the embryo in W22-emb is apparently small or even invisible. In contrast, the emb endosperm develops into a relative normal size. We cloned the mutant gene on the Chromosome 7L and designated it emb-7L. This gene is generally expressed, but it has a relatively higher expression level in leaves. Emb-7L encodes a chloroplast-localized P-type pentatricopeptide repeat (PPR) protein, consistent with the severe chloroplast deficiency in emb-7L albino seedling leaves. Full transcriptome analysis of the leaves of WT and emb-7L seedlings reveals that transcription of chloroplast protein-encoding genes are dramatically variable with pre-mRNA intron splicing apparently affected in a tissue-dependent pattern and the chloroplast structure and activity were dramatically affected including chloroplast membrane and photosynthesis machinery component and synthesis of metabolic products (e.g., fatty acids, amino acids, starch).


Assuntos
Proteínas de Plantas/genética , Processamento de RNA , Transcriptoma , Zea mays/genética , Cloroplastos/genética , Cloroplastos/ultraestrutura , Endosperma/embriologia , Endosperma/genética , Endosperma/crescimento & desenvolvimento , Endosperma/ultraestrutura , Regulação da Expressão Gênica de Plantas , Genes de Cloroplastos/genética , Íntrons/genética , Mutação , Fotossíntese , Folhas de Planta/embriologia , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/ultraestrutura , Precursores de RNA/genética , Plântula/embriologia , Plântula/genética , Plântula/crescimento & desenvolvimento , Plântula/ultraestrutura , Zea mays/embriologia , Zea mays/crescimento & desenvolvimento , Zea mays/ultraestrutura
6.
BMC Genomics ; 20(1): 703, 2019 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-31500568

RESUMO

BACKGROUND: 'Candidatus Phytoplasma solani' is endemic in Europe and infects a wide range of weeds and cultivated plants. Phytoplasmas are prokaryotic plant pathogens that colonize the sieve elements of their host plant, causing severe alterations in phloem function and impairment of assimilate translocation. Typical symptoms of infected plants include yellowing of leaves or shoots, leaf curling, and general stunting, but the molecular mechanisms underlying most of the reported changes remain largely enigmatic. To infer a possible involvement of Fe in the host-phytoplasma interaction, we investigated the effects of 'Candidatus Phytoplasma solani' infection on tomato plants (Solanum lycopersicum cv. Micro-Tom) grown under different Fe regimes. RESULTS: Both phytoplasma infection and Fe starvation led to the development of chlorotic leaves and altered thylakoid organization. In infected plants, Fe accumulated in phloem tissue, altering the local distribution of Fe. In infected plants, Fe starvation had additive effects on chlorophyll content and leaf chlorosis, suggesting that the two conditions affected the phenotypic readout via separate routes. To gain insights into the transcriptional response to phytoplasma infection, or Fe deficiency, transcriptome profiling was performed on midrib-enriched leaves. RNA-seq analysis revealed that both stress conditions altered the expression of a large (> 800) subset of common genes involved in photosynthetic light reactions, porphyrin / chlorophyll metabolism, and in flowering control. In Fe-deficient plants, phytoplasma infection perturbed the Fe deficiency response in roots, possibly by interference with the synthesis or transport of a promotive signal transmitted from the leaves to the roots. CONCLUSIONS: 'Candidatus Phytoplasma solani' infection changes the Fe distribution in tomato leaves, affects the photosynthetic machinery and perturbs the orchestration of root-mediated transport processes by compromising shoot-to-root communication.


Assuntos
Acholeplasmataceae/fisiologia , Ferro/metabolismo , Lycopersicon esculentum/metabolismo , Lycopersicon esculentum/microbiologia , Transporte Biológico , Cloroplastos/metabolismo , Cloroplastos/ultraestrutura , Flores/crescimento & desenvolvimento , Perfilação da Expressão Gênica , Lycopersicon esculentum/genética , Lycopersicon esculentum/crescimento & desenvolvimento , Fotossíntese/genética , Doenças das Plantas/genética , Folhas de Planta/microbiologia , Raízes de Plantas/microbiologia
7.
Int J Mol Sci ; 20(18)2019 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-31500108

RESUMO

The chloroplast RNA splicing and ribosome maturation (CRM) domain proteins are involved in the splicing of chloroplast gene introns. Numerous CRM domain proteins have been reported to play key roles in chloroplast development in several plant species. However, the functions of CRM domain proteins in chloroplast development in rice remain poorly understood. In the study, we generated oscaf1 albino mutants, which eventually died at the seedling stage, through the editing of OsCAF1 with two CRM domains using CRISPR/Cas9 technology. The mesophyll cells in oscaf1 mutant had decreased chloroplast numbers and damaged chloroplast structures. OsCAF1 was located in the chloroplast, and transcripts revealed high levels in green tissues. In addition, the OsCAF1 promoted the splicing of group IIA and group IIB introns, unlike orthologous proteins of AtCAF1 and ZmCAF1, which only affected the splicing of subgroup IIB introns. We also observed that the C-terminal of OsCAF1 interacts with OsCRS2, and OsCAF1-OsCRS2 complex may participate in the splicing of group IIA and group IIB introns in rice chloroplasts. OsCAF1 regulates chloroplast development by influencing the splicing of group II introns.


Assuntos
Cloroplastos/fisiologia , Proteínas de Plantas/metabolismo , Domínios e Motivos de Interação entre Proteínas , Fatores de Processamento de RNA/metabolismo , Cloroplastos/ultraestrutura , Regulação da Expressão Gênica de Plantas , Mutação , Oryza/genética , Oryza/metabolismo , Fenótipo , Proteínas de Plantas/química , Proteínas de Plantas/genética , Ligação Proteica , Processamento de RNA , Fatores de Processamento de RNA/química , Fatores de Processamento de RNA/genética , Espécies Reativas de Oxigênio , Ribossomos/metabolismo , Plântula/genética , Plântula/metabolismo
8.
Plant Physiol Biochem ; 142: 351-362, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31422174

RESUMO

Cassava is an important tropical crop with strong resistance to drought stress. The chloroplast, the site of photosynthesis, is sensitive to stress, and the drought-response proteins in cassava chloroplasts are worthy of investigation. In this study, cassava leaves were collected for ultra-structure observation from plants subjected to different drought stress conditions. Our results showed that drought stress can promote starch accumulation in cassava chloroplasts. To evaluate changes in chloroplast proteins under different drought conditions, two-dimensional electrophoresis was performed using purified chloroplasts, which resulted in the identification of 26 unique chloroplast proteins responsive to drought stress. These drought-responsive proteins are predominantly related to photosynthesis, carbon and nitrogen metabolism, and amino acid metabolism. Among them, most photosynthesis-related proteins are downregulated, with decreases in photosynthetic parameters upon drought stress. Several proteins associated with carbon and nitrogen metabolism, including rubisco and carbonic anhydrase, were upregulated, which might promote drought tolerance in cassava by enhancing the carbohydrate conversion efficiency and protecting the plant from oxidative stress. Our proteomic data not only provide insight into the complement of proteins in cassava chloroplasts but also further our overall understanding of drought-responsive proteins in cassava chloroplasts.


Assuntos
Cloroplastos/metabolismo , Manihot/metabolismo , Folhas de Planta/metabolismo , Proteoma/metabolismo , Cloroplastos/fisiologia , Cloroplastos/ultraestrutura , Desidratação , Eletroforese em Gel Bidimensional , Manihot/fisiologia , Microscopia Eletrônica de Transmissão , Fotossíntese , Folhas de Planta/fisiologia , Folhas de Planta/ultraestrutura , Proteínas de Plantas/metabolismo , Proteínas de Plantas/fisiologia , Proteoma/fisiologia , Reação em Cadeia da Polimerase em Tempo Real
9.
Microscopy (Oxf) ; 68(5): 379-384, 2019 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-31340024

RESUMO

Novel para-crystalline structures resembling prolamellar bodies in etioplasts were found in the invasion zones of indeterminate root nodules of Vicia faba, which possess persistent meristems and exhibit sequential developmental stages. The para-crystalline structures existed in most cells in the area of the invasion zone and a hexagonal arrangement of tubular membranes was recognized. Extensive membranes, apparently procured from the structures, were often in contact with the bacteria in young infected cells. We propose that the para-crystalline structures serve as a reservoir of membranes for the formation of the numerous symbiosomes that propagate and fill the infected cells, and suggest naming them pro-symbiosome membrane bodies.


Assuntos
Cloroplastos/ultraestrutura , Cristalização , Nódulos Radiculares de Plantas/ultraestrutura , Vicia faba/anatomia & histologia , Membrana Celular/ultraestrutura , Microscopia Eletrônica , Vicia faba/ultraestrutura
10.
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
11.
BMC Plant Biol ; 19(1): 253, 2019 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-31196035

RESUMO

BACKGROUND: Because of their broad applications in our life, nanoparticles are expected to be present in the environment raising many concerns about their possible adverse effects on the ecosystem of plants. The aim of this study was to examine the effect of different sizes and concentrations of iron oxide nanoparticles [(Fe3O4) NPs] on morphological, physiological, biochemical, and ultrastructural parameters in tobacco (Nicotiana tabacum var.2 Turkish). RESULTS: Lengths of shoots and roots of 5 nm-treated plants were significantly decreased in all nanoparticle-treated plants compared to control plants or plants treated with any concentration of 10 or 20 nm nanoparticles. The photosynthetic rate and leaf area were drastically reduced in 5 nm (Fe3O4) NP-treated plants of all concentrations compared to control plants and plants treated with 10 or 20 nm (Fe3O4) NPs. Accumulation of sugars in leaves showed no significant differences between the control plants and plants treated with iron oxide of all sizes and concentrations. In contrast, protein accumulation in plants treated with 5 nm iron oxide dramatically increased compared to control plants. Moreover, light and transmission electron micrographs of roots and leaves revealed that roots and chloroplasts of 5 nm (Fe3O4) NPs-treated plants of all concentrations were drastically affected. CONCLUSIONS: The size and concentration of nanoparticles are key factors affecting plant growth and development. The results of this study demonstrated that the toxicity of (Fe3O4) NPs was clearly influenced by size and concentration. Further investigations are needed to elucidate more about NP toxicity in plants, especially at the molecular level.


Assuntos
Nanopartículas Metálicas , Tabaco/efeitos dos fármacos , Cloroplastos/efeitos dos fármacos , Cloroplastos/ultraestrutura , Relação Dose-Resposta a Droga , Compostos Férricos/farmacologia , Microscopia Eletrônica de Transmissão , Fotossíntese/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Folhas de Planta/ultraestrutura , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/ultraestrutura , Brotos de Planta/efeitos dos fármacos , Tabaco/metabolismo , Tabaco/ultraestrutura
12.
Ecotoxicol Environ Saf ; 181: 146-154, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31177079

RESUMO

The impact of lead (Pb) on Spirodela polyrhiza was studied to determine the subcellular distribution, chemical forms, and resulting morphophysiological modifications after treatments with 20 or 80 µM Pb(NO3)2 for 10 days. At the subcellular level, the Pb uptake by S. polyrhiza was mainly compartmentalized in the cell walls (70%), and the majority of Pb (approximately 70%) was extracted using 1 M NaCl and 2% acetic acid (HAc). Visual symptoms of phytotoxcity, surface roughness and closure of stomata, were observed in Pb-treated fronds. Electron-dense precipitates were present in cell walls, and changes to the ultrastructure were most noticeably exhibited in organelle shape, internal organization, and size of the plastoglobules of chloroplasts. Toxic concentrations of Pb induced oxidative stress in fronds, characterized by an accumulation of malondialdehyde (MDA) and decreased chlorophyll and unsaturated fatty acid contents. Pb exposure increased ABS/RC, TRo/RC, DIo/RC, Vj, and φDo (Fv/Fm), indicating that reaction centers were transformed to dissipation sinks, leading to a decrease in the efficiency of photosystem II, which was evident from the decreased values of Fv/Fo, Fv/Fm, ψEo, φEo, RC/ABS, and PIabs. These results indicated that decreased photosynthesis in Pb-treated fronds was partially ascribed to the lower pigment content, inhibition of electron transport, inactivation of the reaction centers, damage to the chloroplast ultrastructure, and stomatal closure. The physiological implications of subcellular distribution and chemical forms are discussed in relation to Pb accumulation and detoxification. However, Pb accumulation significantly impaired photosynthesis and membrane integrity in the fronds of S. polyrhiza.


Assuntos
Araceae/efeitos dos fármacos , Chumbo/toxicidade , Araceae/anatomia & histologia , Araceae/metabolismo , Araceae/ultraestrutura , Clorofila/metabolismo , Cloroplastos/efeitos dos fármacos , Cloroplastos/ultraestrutura , Transporte de Elétrons/efeitos dos fármacos , Ácidos Graxos Insaturados/metabolismo , Chumbo/farmacocinética , Malondialdeído/metabolismo , Fotossíntese/efeitos dos fármacos , Complexo de Proteína do Fotossistema II/metabolismo
13.
Planta ; 250(2): 643-655, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31144110

RESUMO

MAIN CONCLUSION: Trehalose increased drought tolerance of tomato plants, accompanied by reduced water loss and closed stomata, which was associated with the upregulated ABA signaling-related genes expression, but not in ABA accumulation. Drought is one of the principal abiotic stresses that negatively influence the growth of plant and yield. Trehalose has great agronomic potential to improve the stress tolerance of plants. However, little information is available on the role of ABA and its signaling components in trehalose-induced drought tolerance. The aim of this study is to elucidate the potential mechanism by which trehalose regulates ABA in response to drought stress. In this study, 6-week-old tomato (Solanum lycopersicum cv. Ailsa Craig) plants were treated with 0 or 15.0 mM trehalose solution. Results showed that trehalose treatment significantly enhanced drought tolerance of tomato plants, accompanied by encouraged stomatal closure and protected chloroplast ultrastructure. Compared with controls, trehalose-treated plants showed lower hydrogen peroxide content and higher antioxidant enzymes activities, which contributed to alleviate oxidative damage caused by drought. Moreover, trehalose treatment decreased ABA content, which was followed by the downregulation of ABA biosynthesis genes expression and the upregulation of ABA catabolism genes expression. In contrast, exogenous trehalose upregulated transcript levels of ABA signaling-related genes, including SlPYL1/3/4/5/6/7/9, SlSnRK2.3/4, SlAREB1/2, and SlDREB1. These results suggested that trehalose treatment enhanced drought tolerance of tomato plants, and it's ABA signaling rather than ABA metabolism that was involved in trehalose-induced drought tolerance in tomato plants. These findings provide evidence for the physiological role of trehalose and bring about a new understanding of the possible relationship between trehalose and ABA.


Assuntos
Ácido Abscísico/metabolismo , Lycopersicon esculentum/fisiologia , Reguladores de Crescimento de Planta/metabolismo , Proteínas de Plantas/metabolismo , Transdução de Sinais , Trealose/farmacologia , Cloroplastos/fisiologia , Cloroplastos/ultraestrutura , Secas , Lycopersicon esculentum/genética , Lycopersicon esculentum/ultraestrutura , Fenótipo , Proteínas de Plantas/genética , Estômatos de Plantas/genética , Estômatos de Plantas/fisiologia , Estômatos de Plantas/ultraestrutura , Estresse Fisiológico
14.
Ecotoxicol Environ Saf ; 180: 333-347, 2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31102841

RESUMO

Arsenic (As) recognized as a group I human carcinogen additionally poses a threat to plants which limit growth, metabolic activity, and productivity. Melatonin (MEL) is a naturally occurring compound in plants that have been recognized to mediate numerous morphological, physiological and molecular processes. Conversely, the role of MEL in inducing As-tolerance remains inexpressible and the plausible mechanisms in inducing As tolerance have remained largely unknown. The present investigation was designed to understand the protective role of MEL concentrations in rosemary herbs cultivated under As contamination. Arsenic evoked a deleterious decline on herb productivity, photosynthetic pigment, ion concentration, water status, ascorbic acid, essential oil (EO) yield and induced malformation of the chloroplast. Alternatively, increased organic osmolytes, oxidative impairment criteria, additionally antioxidant enzymes, phenol, flavonoid, anthocyanin, and EO%. Exogenous application of MEL with or without As, considerably increased growth, photosynthetic pigment, ion concentration, organic osmolytes as well as EO yield regarding polluted or non-polluted treatment respectively. Moreover, MEL treatment stabilized the cell membrane integrity, suppressed oxidative impairment criteria, and enhanced antioxidant capacity, additionally upregulation antioxidant enzymes. Plant treated with As showed a significant increase in As contamination and a bioconcentration factor in both root and shoot system. MEL supplementation under normal or As concentration, reduced As accumulation and bioconcentration factors, in either shoot or root systems. Additionally As decrease transfer factor, however, supplementation of MEL further decreased it. Application of 50 µM MEL might help the herbs to withstand As stress by strengthening their antioxidant machinery and osmoregulation capacity.


Assuntos
Antioxidantes/metabolismo , Arsênico/toxicidade , Cloroplastos/ultraestrutura , Melatonina/farmacologia , Rosmarinus/efeitos dos fármacos , Poluentes do Solo/toxicidade , Arsênico/metabolismo , Tolerância a Medicamentos , Estresse Oxidativo/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Rosmarinus/metabolismo , Poluentes do Solo/metabolismo
15.
Theor Appl Genet ; 132(7): 2069-2086, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30953093

RESUMO

KEY MESSAGE: The vsp gene was fine mapped to a 353.7-kb region, and a 201-bp deletion that affected chloroplast development and chlorophyll biosynthesis was found in the candidate gene GhPUR4. Virescent mutations can be used as marker traits in heterosis breeding and can also be used to research chloroplast development, chlorophyll biosynthesis and photosynthesis mechanisms. Here, we obtained a light-sensitive virescent mutant, vsp, that has reduced chlorophyll (Chl) content and abnormal chloroplast development. Then, the virescent space (vsp) gene in the vsp mutant was preliminarily mapped to a 38.32-Mb region of chromosome D04 using a high-density SNP genetic map with a total length of 5384.33 cM and 4472 bin markers. Furthermore, the vsp gene was narrowed down to a 353.7-kb region that contains 15 candidate genes using 484 virescent individuals from an F2 population. Sequence analysis of genes in this region showed that a 201-bp deletion was present in the Gh_D04G1108 (GhPUR4) gene in the vsp mutant. The 201-bp deletion of Gh_D04G1108 caused the deletion of 67 AAs in the GhPUR4 protein. Virus-induced gene silencing (VIGS) of GhPUR4 in normal plants caused reduced GhPUR4 gene expression levels, reduced Chl content, abnormal chloroplast development and virescent true leaves. This study could help us unravel the function of GhPUR4 in chloroplast development and Chl biosynthesis at the early developmental stages of the true leaves in cotton, which could promote the research and application of virescent mutations in cotton heterosis breeding.


Assuntos
Clorofila/análise , Cloroplastos/fisiologia , Mapeamento Cromossômico , Gossypium/genética , Sequência de Aminoácidos , Cloroplastos/ultraestrutura , Genes de Plantas , Gossypium/fisiologia , Microscopia Eletrônica de Transmissão , Fenótipo , Melhoramento Vegetal , Folhas de Planta/crescimento & desenvolvimento , Deleção de Sequência
16.
J Sci Food Agric ; 99(10): 4816-4824, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-30980406

RESUMO

BACKGROUND: In some cultivars, yellowing resulting from chlorophyll breakdown has a direct and negative effect on food supply and health. The 'Zaosu' pear (Pyrus bretschneideri Rehd.), a commercial Asian pear cultivar in China, rapidly turns yellow when stored at room temperature after harvest. To develop techniques that delay or suppress chlorophyll degradation, the effects of methyl salicylate (MeSA) on yellowing in 'Zaosu' pear fruit during storage were evaluated. RESULTS: Compared with the untreated fruit, the application of 0.05 mmol L-1 MeSA delayed the decline of the total chlorophyll, chlorophyll a and chlorophyll b content, and maintained more intact chloroplasts with fewer and smaller plastoglobuli. Methyl salicylate suppressed enzyme activities, including chlorophyllase, chlorophyll-degrading peroxidase, Mg dechelatase, and pheophytinase, and the expression levels of NYC, NOL, CLH, SGR, PPH, PAO and RCCR in treated fruit. CONCLUSION: Methyl salicylate could delay chlorophyll breakdown in the fruit. The results also suggested that the conversion from chlorophyll a to pheophorbide a could proceed via two pathways, and that alternative pathways for the breakdown of chlorophyll a exist in 'Zaosu' pears. © 2019 Society of Chemical Industry.


Assuntos
Clorofila A/metabolismo , Clorofila/metabolismo , Conservação de Alimentos/métodos , Conservantes de Alimentos/farmacologia , Pyrus/efeitos dos fármacos , Salicilatos/farmacologia , Clorofila/análise , Clorofila A/análise , Cloroplastos/efeitos dos fármacos , Cloroplastos/metabolismo , Cloroplastos/ultraestrutura , Armazenamento de Alimentos , Frutas/efeitos dos fármacos , Frutas/metabolismo , Frutas/ultraestrutura , Pyrus/metabolismo , Pyrus/ultraestrutura
17.
PLoS One ; 14(4): e0214811, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30946768

RESUMO

Plastids perform many essential functions in plant metabolism including photosynthesis, synthesis of metabolites, and stress signaling. The most prominent type in green leaves is the chloroplast which contains thylakoids, plastoglobules, and starch. As these structures are closely linked to the metabolism of chloroplasts, changes during plant growth and development and during environmental stress situations are likely to occur. The aim of this study was to characterize changes in size and ultrastructure of chloroplast on cross-sections of leaves during high light stress, Botrytis infection, and dark induced senescence by quantitative transmission electron microscopy (TEM).The size of chloroplasts on cross sections of leaves decreased significantly when plants were subject to high light (49%), Botrytis infection (58%), and senescence (71%). The number of chloroplasts on cross sections of the palisade cell layer and spongy parenchyma, respectively, decreased significantly in plants exposed to high light conditions (48% and 29%), infected with Botrytis (48% and 46%), and during senescence (78% and 80%). Thylakoids on cross-sections of chloroplasts decreased significantly in plants exposed to high light (22%), inoculated with Botrytis cinerea (36%), and senescence (51%). This correlated with a massive increase in plastoglobules on cross-sections of chloroplasts of 88%, 2,306% and 19,617%, respectively. Starch contents on cross sections of chloroplasts were completely diminished in all three stress scenarios. These results demonstrate that the decrease in the number and size of chloroplasts is a reliable stress marker in plants during abiotic and biotic stress situations which can be easily detected with a light microscope. Further, lack of starch, the occurrence of large plastoglobules and decrease in thylakoids can also be regarded as reliable stress marker in plants which can be detected by TEM.


Assuntos
Plastídeos/ultraestrutura , Arabidopsis/metabolismo , Arabidopsis/microbiologia , Arabidopsis/ultraestrutura , Botrytis/patogenicidade , Cloroplastos/metabolismo , Cloroplastos/ultraestrutura , Luz , Microscopia Eletrônica de Transmissão , Doenças das Plantas/microbiologia , Folhas de Planta/metabolismo , Folhas de Planta/ultraestrutura , Plastídeos/metabolismo , Amido/metabolismo , Estresse Fisiológico , Tilacoides/metabolismo , Tilacoides/ultraestrutura
18.
ISME J ; 13(8): 2094-2106, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31024153

RESUMO

Most aquatic photoautotrophs depend on CO2-concentrating mechanisms (CCMs) to maintain productivity at ambient concentrations of CO2, and carbonic anhydrase (CA) plays a key role in these processes. Here we present different lines of evidence showing that the protein LCIP63, identified in the marine diatom Thalassiosira pseudonana, is a CA. However, sequence analysis showed that it has a low identity with any known CA and therefore belongs to a new subclass that we designate as iota-CA. Moreover, LCIP63 unusually prefers Mn2+ to Zn2+ as a cofactor, which is potentially of ecological relevance since Mn2+ is more abundant than Zn2+ in the ocean. LCIP63 is located in the chloroplast and only expressed at low concentrations of CO2. When overexpressed using biolistic transformation, the rate of photosynthesis at limiting concentrations of dissolved inorganic carbon increased, confirming its role in the CCM. LCIP63 homologs are present in the five other sequenced diatoms and in other algae, bacteria, and archaea. Thus LCIP63 is phylogenetically widespread but overlooked. Analysis of the Tara Oceans database confirmed this and showed that LCIP63 is widely distributed in marine environments and is therefore likely to play an important role in global biogeochemical carbon cycling.


Assuntos
Dióxido de Carbono/metabolismo , Carbono/metabolismo , Anidrases Carbônicas/genética , Diatomáceas/enzimologia , Fitoplâncton/enzimologia , Sequência de Aminoácidos , Anidrases Carbônicas/metabolismo , Cloroplastos/enzimologia , Cloroplastos/ultraestrutura , Coenzimas , Bases de Dados de Ácidos Nucleicos , Diatomáceas/genética , Diatomáceas/ultraestrutura , Geografia , Microscopia Eletrônica de Transmissão , Oceanos e Mares , Fotossíntese , Filogenia , Fitoplâncton/genética , Fitoplâncton/ultraestrutura , Alinhamento de Sequência
19.
BMC Plant Biol ; 19(1): 107, 2019 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-30890144

RESUMO

BACKGROUND: Nitrogen (N) metabolism plays an important role in plant drought tolerance. 2-(3,4-Dichlorophenoxy) triethylamine (DCPTA) regulates many aspects of plant development; however, the effects of DCPTA on soil drought tolerance are poorly understood, and the possible role of DCPTA on nitrogen metabolism has not yet been explored. RESULTS: In the present study, the effects of DCPTA on N metabolism in maize (Zea mays L.) under soil drought and rewatering conditions during the pre-female inflorescence emergence stage were investigated in 2016 and 2017. The results demonstrated that the foliar application of DCPTA (25 mg/L) significantly alleviated drought-induced decreases in maize yield, shoot and root relative growth rate (RGR), leaf relative water content (RWC), net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr), and nitrate (NO3-), nitrite (NO2-), soluble protein contents, and nitrate reductase (NR), nitrite reductase (NiR), isocitrate dehydrogenase (ICDH), alanine aminotransferase (AlaAT) and aspartate aminotransferase (AspAT) activities. In addition, the foliar application of DCPTA suppressed the increases of intercellular CO2 concentration (Ci), ammonium (NH4+) and free amino acid contents, and the glutamate dehydrogenase (GDH) and protease activities of the maize. Simultaneously, under drought conditions, the DCPTA application improved the spatial and temporal distribution of roots, increased the root hydraulic conductivity (Lp), flow rate of root-bleeding sap and NO3- delivery rates of the maize. Moreover, the DCPTA application protected the chloroplast structure from drought injury. CONCLUSIONS: The data show, exogenous DCPTA mitigates the repressive effects of drought on N metabolism by maintained a stabilized supply of 2-oxoglutarate (2-OG) and reducing equivalents provided by photosynthesis via favorable leaf water status and chloroplast structure, and NO3- uptake and long-distance transportation from the roots to the leaves via the production of excess roots, as a result, DCPTA application enhances drought tolerance during the pre-female inflorescence emergence stage of maize.


Assuntos
Etilaminas/farmacologia , Nitrogênio/metabolismo , Osmorregulação/efeitos dos fármacos , Proteínas de Plantas/metabolismo , Zea mays/efeitos dos fármacos , Zea mays/metabolismo , Compostos de Amônio/metabolismo , Cloroplastos/efeitos dos fármacos , Cloroplastos/ultraestrutura , Secas , Isocitrato Desidrogenase/metabolismo , Nitratos/metabolismo , Nitritos/metabolismo , Desenvolvimento Vegetal/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Brotos de Planta/crescimento & desenvolvimento , Transpiração Vegetal/efeitos dos fármacos , Solo , Água/fisiologia , Zea mays/crescimento & desenvolvimento
20.
Plant Sci ; 280: 321-329, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30824011

RESUMO

Cysteine functions not only as an amino acid in proteins but also as a precursor for a large number of essential biomolecules. Cysteine is synthesized via the incorporation of sulfide to O-acetylserine under the catalysis of O-acetylserine(thiol)lyase (OASTL). In dicotyledonous Arabidopsis, nine OASTL genes have been reported. However, in their null mutants, only the mutant of CS26 encoding S-sulfocysteine synthase showed the visible phenotypic changes, displaying significantly small plants and pale-green leaves under long-day condition but not short-day condition. Up to now, no OASTL gene or mutant has been identified in monocotyledon. In this study, we isolated a green-revertible albino mutant gra78 in rice (Oryza sativa). Its albino phenotype at the early seedling stage was sensitive to temperature but independent of photoperiod. Map-based cloning revealed that candidate gene LOC_Os01g59920 of GRA78 encodes a putative S-sulfocysteine synthase showing significant similarity with Arabidopsis CS26. Complementation experiment confirmed that mutation in LOC_Os01g59920 accounted for the mutant phenotype of gra78. GRA78 is constitutively expressed in all tissues and its encoded protein is targeted to the chloroplast. In addition, qRT-PCR suggested that expression levels of four OASTL homolog genes and five photosynthetic genes were remarkably down-regulated.


Assuntos
Liases/metabolismo , Oryza/enzimologia , Cloroplastos/fisiologia , Cloroplastos/ultraestrutura , Liases/genética , Liases/ultraestrutura , Mutação , Oryza/genética , Oryza/crescimento & desenvolvimento , Oryza/ultraestrutura , Fenótipo , Fotossíntese , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plântula/enzimologia , Plântula/genética , Plântula/crescimento & desenvolvimento , Plântula/ultraestrutura
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