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1.
Ying Yong Sheng Tai Xue Bao ; 30(9): 2941-2948, 2019 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-31529868

RESUMO

To explore the photosynthetic adaptation of Phoebe bournei to different light conditions, two-year-old P. bournei seedlings were grown under three light regimes (full light, shading rate 50% and 78% of full light). The chlorophyll contents, leaf gas exchange and chlorophyll fluorescence of P. bournei were measured after six-month treatment. The results showed that the contents of chlorophyll a, chlorophyll b, chlorophyll (a+b) and carotenoids in leaves were in a descending order of shading rate 78% > shading rate 50% > full light. There was no significant difference of chlorophyll a/b between natural and shade treatments. The shading treatment reduced light compensation point (LCP), but increased light saturation point (LSP) and apparent quantum yield (AQY), suggesting that plants could utilize both the weak light and the high light. Maximum net photosynthetic rate (Pn max), dark respiration rate (Rd), and maximum electron transfer rate (Jmax) increased under the shading treatment. There was significant difference between natural and shade treatment in net photosynthetic rate (Pn), stomatal conductance to CO2(gsc), intercellular CO2 concentration (Ci), and mesophyll conductance (gm). Pn and gm of different light regimes were sorted from the highest to the lowest as shading rate 78% > shading rate 50% > full light. gsc under shading rate 78% was higher than that under full light. Ci under shading rate 50% and 78% were lower than that under full light. Actual photochemical efficiency of PS2 (Fv'/Fm'), quantum yields of PS2 (ΦPS2), and electron transport rate (J) of P. bournei leaves were significantly higher under shading rate 78% than those under shading rate 50% and full light. In conclusion, P. bournei could increase Pn by increasing chlorophyll content, AQY, J, gsc, and gm under shade condition.


Assuntos
Clorofila/metabolismo , Lauraceae/fisiologia , Folhas de Planta/metabolismo , Clorofila/análise , Clorofila A , Fotossíntese/fisiologia , Folhas de Planta/química , Plântula , Luz Solar
2.
Biol Res ; 52(1): 46, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31434576

RESUMO

BACKGROUND: One of the most extreme environments on our planet is the Maritime Antarctic territory, due to its low-water availability, which restricts the development of plants. Sanionia uncinata Hedw. (Amblystegiaceae), the main colonizer of the Maritime Antarctic, has effective mechanisms to tolerate this environment. It has been described that the tolerance to desiccation is mediated by the hormone abscisic acid (ABA), antioxidants systems, accumulation of compatible solutes and proteins of the late embryogenesis abundant (LEA). However, to date, these mechanisms have not been described in S. uncinata. Therefore, in this work, we postulate that the tolerance to desiccation in the Antarctic moss S. uncinata is mediated by the accumulation of ABA, the osmolytes proline and glycine betaine, and dehydrins (an LEA class 11 proteins). To demonstrate our hypothesis, S. uncinata was subjected to desiccation for 24 h (loss in 95% of water content), and the effects on its physiological, photosynthetic, antioxidant and biochemical parameters were determined. RESULTS: Our results showed an accumulation of ABA in response to water loss, and the activation of protective responses that involves an increment in levels of proline and glycine betaine, an increment in the activity of antioxidant enzymes such as SOD, CAT, APX and POD, and the accumulation of dehydrins proteins. CONCLUSION: The results showed, suggest that S. uncinata is a  desiccation-tolerant moss, property mediated by high cellular plasticity regulated by ABA.


Assuntos
Antioxidantes/análise , Bryopsida/fisiologia , Dessecação , Fotossíntese/fisiologia , Adaptação Fisiológica , Regiões Antárticas , Bryopsida/química , Bryopsida/classificação , Fatores de Tempo
3.
Environ Pollut ; 253: 646-654, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31330356

RESUMO

Although plants are often exposed to atmospheric nanoparticles (NPs), the mechanism of NP deposition and their effects on physiology and metabolism, and particularly in combination with other stressors, are not yet understood. Exploring interactions between stressors is particularly important for understanding plant responses in urban environments where elevated temperatures can be associated with air pollution. Accordingly, 3-year-old spruce seedlings were exposed for 2 weeks to aerial cadmium oxide (CdO) NPs of environmentally relevant size (8-62 nm) and concentration (2 × 105 cm-3). While half the seedlings were initially acclimated to high temperature (35 °C) and vapour pressure deficit (VPD; 2.81 kPa), the second half of the plants were left under non-stressed conditions (20 °C, 0.58 kPa). Atomic absorption spectrometry was used to determine Cd content in needles, while gas and liquid chromatography was used to determine changes in primary and secondary metabolites. Photosynthesis-related processes were explored with gas-exchange and chlorophyll fluorescence systems. Our work supports the hypothesis that atmospheric CdO NPs penetrate into leaves but high temperature and VPD reduce such penetration due to stomatal closure. The hypothesis that atmospheric CdO NPs influences physiological and metabolic processes in plants was also confirmed. This impact strengthens with increasing time of exposure. Finally, we found evidence that plants acclimated to stress conditions have different sensitivity to CdO NPs compared to plants not so acclimated. These findings have important consequences for understanding impacts of global warming on plants and indicates that although the effects of elevated temperatures can be deleterious, this may limit other forms of plant stress associated with air pollution.


Assuntos
Poluentes Atmosféricos/toxicidade , Compostos de Cádmio/toxicidade , Nanopartículas/toxicidade , Óxidos/toxicidade , Picea/efeitos dos fármacos , Temperatura Ambiente , Abies , Aclimatação/fisiologia , Poluentes Ambientais/metabolismo , Aquecimento Global , Temperatura Alta , Fotossíntese/fisiologia , Picea/fisiologia , Pinus , Folhas de Planta/efeitos dos fármacos , Plântula/efeitos dos fármacos
4.
Ying Yong Sheng Tai Xue Bao ; 30(6): 1861-1868, 2019 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-31257757

RESUMO

Hydroponic experiment was carried out on M9T337 seedlings using 15N and 13C isotope tracer technology to study the effects of different potassium supply levels (K0, K1, K2, K3 and K4 were equivalent to 0, 3, 6, 9 and 12 mmol·L-1, respectively) on the growth, photosynthetic characteristics and 15N and 13C absorption and utilization of M9T337 seedlings. The results showed that dry mass, root length, root surface area, number of tips and root activity of M9T337 seedlings under the K2 level were significantly higher than those under other levels. The net photosynthetic rate (Pn) of leaves increased at low K+ concentration and then decreased with the increases of potassium supply level, and reached the maximum value at K2 treatment (15.5 µmol CO2·m-2·s-1). At the 30th day after treatment, the activities of nitrate reductase (NR) and carbon metabolism enzyme were highest in K2 treatment, and lowest in K0 treatment. With the increases of potassium application rate, the 13C accumulation of seedlings were first increased and then decreased, with the 13C distribution rate of each organ being the most balanced at K2 treatment. There were significant differences in 15N uptake and utilization rate among treatments. 15N uptake and utilization rates of seedlings under K2 treatment were the highest, which were 16.1 mg and 17.9%, respectively. Therefore, too low or too high potassium supply could inhibit seedling root growth and leaf photosynthesis, which was not conducive to carbon and nitrogen absorption. Appropriate potassium supply could improve root activity and net photosynthetic rate, enhance nitrate reductase (NR) and carbon metabolic enzyme activity, and promote carbon and nitrogen metabolism.


Assuntos
Fotossíntese/fisiologia , Potássio/metabolismo , Plântula/fisiologia , Isótopos de Carbono/metabolismo , Nitrogênio , Isótopos de Nitrogênio/metabolismo , Folhas de Planta
5.
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
6.
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
7.
Plant Cell Rep ; 38(9): 1181-1197, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31165250

RESUMO

KEY MESSAGE: Drastic changes in soil water content can activate the short-term high expression of key enzyme-encoding genes involved in secondary metabolite synthesis thereby increasing the content of secondary metabolites. Bupleurum chinense DC. is a traditional medicinal herb that is famous for its abundant saikosaponins. In the current study, the effects of drought-re-watering-drought on the photosynthesis physiology and biosynthesis of saikosaponins were investigated in 1-year-old B. chinense. The results showed that alterations in soil moisture altered the photosynthesis physiological process of B. chinense. The dry weight and fresh weight of the roots, photosynthesis capacity, chlorophyll fluorescence parameters, and SOD, POD and CAT activities were significantly reduced, and the contents of SP, soluble sugars, PRO and MDA increased. There were strong correlations between different physiological stress indices. All indices promoted and restricted each other, responded to soil moisture changes synergistically, maintained plant homeostasis and guaranteed normal biological activities. It was found that RW and RD_1 were the key stages of the water-control experiment affecting the expression of saikosaponin-related genes. At these two stages, the expression of multiple genes was affected by changes in soil moisture, with their expression levels reaching several-fold higher than those at the previous stage. We noticed that the expression of saikosaponin synthesis genes (which were rapidly upregulated at the RW and RD_1 stages) did not coincide with the rapid accumulation of saikosaponins (at the RD-2 stage), which were found to correspond to each other at the later stages of the water-control experiment. This finding indicates that there is a time lag between gene expression and the final product synthesis. Rapid changes in the external environment (RW to RD_1) have a short-term promoting effect on gene expression. This study reveals that short-term stress regulation may be an effective way to improve the quality of medicinal materials.


Assuntos
Bupleurum/fisiologia , Ácido Oleanólico/análogos & derivados , Fotossíntese/fisiologia , Saponinas/biossíntese , Metabolismo Secundário , Água/fisiologia , Bupleurum/química , Secas , Ácido Oleanólico/biossíntese , Raízes de Plantas/química , Raízes de Plantas/fisiologia , Plantas Medicinais , Solo/química , Estresse Fisiológico
8.
Mar Pollut Bull ; 144: 196-204, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31179988

RESUMO

Although many achievements have been made in studies on the relationship between Symbiodiniaceae and coral bleaching, there is little information on the responses of Symbiodiniaceae to coral thermal bleaching in the South China Sea (SCS). In this study, Symbiodiniaceae communities and the effective quantum yield (ФPSII) of healthy and bleached massive corals from the SCS were compared. The results indicated that the Symbiodiniaceae communities and ФPSII values showed coral bleaching-dependent variations. Specifically, the relative abundances of the rare putatively thermally tolerant Durusdinium sp. (D1) and the Symbiochlorum hainanensis increased significantly in the bleached corals. In addition, bleached Porites lutea was mainly associated with the putatively thermally tolerant Cladocopium sp. (C15 and C91) and exhibited the highest ФPSII value compared with other bleached corals. These results highlight that the rare putatively thermally tolerant algae and coral species-specific algae may be important for understanding thermal bleaching of corals.


Assuntos
Antozoários/crescimento & desenvolvimento , Dinoflagelados/crescimento & desenvolvimento , Monitoramento Ambiental/métodos , Fotossíntese/fisiologia , Pigmentação/fisiologia , Adaptação Fisiológica , Animais , Antozoários/fisiologia , China , Temperatura Alta , Água do Mar/química
9.
Environ Sci Pollut Res Int ; 26(19): 19982-19990, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31093915

RESUMO

To study the combined effects of multiple nitrogen (N) sources and salinity on the growth and physiology on macroalgae, we cultured Ulva prolifera under three N levels (N0, 0.1235 mg L-1; N1, 0.6 mg L-1; and N2, 4.4 mg L-1; the ratios were 18:74:8 for NH4-N, NO3-N, and NO2-N, respectively) and three salinity conditions (15, 25, and 35). Then, the growth, pigment content, photosynthetic performance, superoxide dismutase (SOD) activity, and contents of soluble protein and carbohydrates were measured. The results showed the following: (1) Compared to that grown at salinity 25, the growth of U. prolifera decreased under salinity 35, especially under the N0 and N2 levels, but there were no significant effects of salinity 15 under any of the N levels. (2) There were no significant effects of salinity on the chlorophyll a (Chla) content, but compared to the content at salinity 25, the chlorophyll b (Chlb) content was enhanced by salinity 15 and 35; lower ratio values between Chla and carotenoids (Car) occurred under the salinity 25 treatment. Under each salinity condition, the pigments were enhanced by a high N level. (3) A relatively higher salinity level decreased the photosynthetic oxygen evolution rate, while a higher N level increased this value. Compared to the rate at salinity 25, the dark respiration rate (Rd) significantly increased at salinity 15 under the N0 condition. (4) SOD activity was enhanced by a high N level, but no significant effects of salinity were observed. (5) The carbohydrate content was enhanced at salinity 35 under the N0 and N1 levels, and under salinity 15, this value increased with increasing N levels. In conclusion, although the growth of U. prolifera decreased at high N levels under high salinity conditions, a high N level induced an increase in photosynthesis, while no significant decrease in growth occurred. These findings indicate that low salinity and high N levels may be nonnegligible reasons why this species thrives, and low salinity was the better choice when this species was used for wastewater treatment.


Assuntos
Nitrogênio/metabolismo , Fotossíntese/fisiologia , Salinidade , Alga Marinha/fisiologia , Ulva/fisiologia , Alga Marinha/química , Alga Marinha/crescimento & desenvolvimento , Ulva/química , Ulva/crescimento & desenvolvimento
10.
Ecotoxicol Environ Saf ; 179: 198-211, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31048216

RESUMO

Among the most intriguing features characterizing extremophile plants is their ability to rapidly recover growth activity upon stress release. Here, we investigated the responses of the halophyte C. maritima to drought and recovery at both physiological and leaf proteome levels. Six week-old plants were either cultivated at 100% or at 25% field capacity. After 12 d of treatment, one lot of dehydrated plants was rewatered to 100% FC for 14 d (stress release). Drought stress impaired shoot hydration, photosynthetic activity and chlorophyll content compared to the control, resulting in severe plant growth restriction. This was concomitant with a marked increase in anthocyanin and proline concentrations. Upon stress release, C. maritima rapidly recovered with respect to all measured parameters. Two-dimensional gel-based proteome analysis of leaves revealed 84 protein spots with significantly changed volumes at the compared conditions: twenty-eight protein spots between normally watered plants and stressed plants but even 70 proteins between stressed and recovered plants. Proteins with higher abundance induced upon rewatering were mostly involved in photosynthesis, glycolytic pathway, TCA cycle, protein biosynthesis, and other metabolic pathways. Overall, C. maritima likely adopts a drought-avoidance strategy, involving efficient mechanisms specifically taking place upon stress release, leading to fast and strong recovery.


Assuntos
Brassicaceae/metabolismo , Secas , Folhas de Planta/metabolismo , Proteoma/metabolismo , Plantas Tolerantes a Sal/metabolismo , Estresse Fisiológico , Clorofila/metabolismo , Fotossíntese/fisiologia , Prolina/metabolismo , Tunísia , Água/metabolismo
11.
Plant Cell Physiol ; 60(8): 1790-1803, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31111914

RESUMO

The elucidation of epigenetic responses of salt-responsive genes facilitates understanding of the underlying mechanisms that confer salt tolerance in rice. However, it is still largely unknown how epigenetic mechanisms are associated with the expression of salt-responsive genes in rice and other crops. In this study, we reported tissue-specific gene expression and tissue-specific changes in chromatin modifications or signatures between seedlings and roots in response to salt treatment. Our study indicated that among six of individual mark examined (H3K4me3, H3K27me3, H4K12ac, H3K9ac, H3K27ac and H3K36me3), a positive association between salt-related changes in histone marks and the expression of differentially expressed genes (DEGs) was observed only for H3K9ac and H4K12ac in seedlings and H3K36me3 in roots. In contrast, chromatin states (CSs) with combinations of six histone modification marks played crucial roles in the differential expression of salt-responsive genes between seedlings and roots. Most importantly, CS7 containing the bivalent marks H3K4me3 and H3K27me3, with a mutual exclusion of functions with each other, displayed distinct functions in the expression of DEGs in both tissues. Specifically, H3K27me3 in CS7 mainly suppressed the expression of DEGs in roots, while H3K4me3 affected the expression of down- and up-regulated genes, possibly by antagonizing the repressive role of H3K27me3 in seedlings. Our findings indicate distinct impacts of the CSs on the differential expression of salt-responsive genes between seedlings and roots in rice, which provides an important background for understanding chromatin-based epigenetic mechanisms that might confer salt tolerance in plants.


Assuntos
Cromatina/metabolismo , Oryza/metabolismo , Raízes de Plantas/metabolismo , Plântula/metabolismo , Divisão Celular/genética , Divisão Celular/fisiologia , Regulação da Expressão Gênica de Plantas , Oryza/genética , Peroxirredoxinas/genética , Peroxirredoxinas/metabolismo , Fotossíntese/genética , Fotossíntese/fisiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/genética , Plântula/genética
12.
Ying Yong Sheng Tai Xue Bao ; 30(5): 1445-1462, 2019 May.
Artigo em Chinês | MEDLINE | ID: mdl-31106998

RESUMO

We examined the effects of nitrogen, soil microbe and their interactions on biomass allocation, growth and photosynthesis of Fraxinus mandschurica, a typical tree species in Changbai Mountain, through outdoor control experiments. In June 2017, an experiment with two-factor randomized block design was carried out. There were four treatments: control (F), nitrogen addition (FN), sterilization (FS), sterilization and nitrogen addition (FSN), six repetitive blocks, three repetitions per block, including 18 repetitions of each treatment. In mid-August 2018, we measured photosynthetic parameters and then harvested seedlings to measure biomass and growth parameters in September. The results showed that compared with F, FN significantly increased total biomass by 14%, basal diameter by 9%, chlorophyll content, net photosynthetic rate (Pn), stomatal conduc-tance (gs), transpiration rate (Tr) by 75%, 318%, 231%, 227% respectively. FS significantly increased total biomass by 13%, basal diameter by 9% and chlorophyll content, Pn, gs and Tr increased by 34%, 213%, 120% and 115%, respectively. FSN increased total biomass by 23%, basal diameter by 14%, chlorophyll content, Pn, gs and Tr increased by 81%, 672%, 312% and 273%, respectively. Nitrogen, soil microbe and their interactions had significant effects on biomass, growth and photosynthesis of F. mandschurica seedlings. Soil microbe would regulate the response of F. mandschurica seedlings to nitrogen.


Assuntos
Fraxinus/fisiologia , Nitrogênio/análise , Fotossíntese/fisiologia , Microbiologia do Solo , Biomassa , Folhas de Planta , Plântula , Solo/química
13.
Plant Physiol Biochem ; 139: 724-730, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31055133

RESUMO

Tree trunks not only provide physical support for canopy leaves but also supply and store water for transpiration. However, the relationships between trunk hydraulic properties and canopy leaf physiology in tropical trees are not well-understood. In this study we concurrently measured morning and midday canopy leaf photosynthesis (A), stomatal conductance (gs), and leaf water potentials (ΨL) in 40 tropical trees representing 14 species at the beginning of the rainy season in Xishuangbanna, Southwest China. We also measured trunk sapwood capacitance (C), wood density, and sap flux density to assess their association with canopy leaf physiology. Among the 14 studied species, only three and four species did not show a significant midday reduction in A and gs respectively. The diurnally maximum A and gs were significantly positively related to sapwood hydraulic capacitance, maximum sap flux density (midday), and sap flux density at 11:00. Those species with lower wood density and higher C showed a lower reduction in ΨL at midday, whereas, species with high C, and large values of maximum sap flux density also showed high carbon assimilation at midday. Our results provide new insights into the close coordination between canopy physiology and trunk sapwood hydraulic properties in tropical trees.


Assuntos
Fotossíntese/fisiologia , Folhas de Planta/metabolismo , Água/metabolismo
14.
World J Microbiol Biotechnol ; 35(5): 77, 2019 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-31069553

RESUMO

Ethylene is a volatile alkene which is used in large commercial scale as a precursor in plastic industry, and is currently derived from petroleum refinement. As an alternative production strategy, photoautotrophic cyanobacteria Synechocystis sp. PCC 6803 and Synechococcus elongatus PCC 7942 have been previously evaluated as potential biotechnological hosts for producing ethylene directly from CO2, by the over-expression of ethylene forming enzyme (efe) from Pseudomonas syringae. This work addresses various open questions related to the use of Synechococcus as the engineering target, and demonstrates long-term ethylene production at rates reaching 140 µL L-1 h-1 OD750-1 without loss of host vitality or capacity to produce ethylene. The results imply that the genetic instability observed earlier may be associated with the expression strategies, rather than efe over-expression, ethylene toxicity or the depletion of 2-oxoglutarate-derived cellular precursors in Synechococcus. In context with literature, this study underlines the critical differences in expression system design in the alternative hosts, and confirms Synechococcus as a suitable parallel host for further engineering.


Assuntos
Etilenos/biossíntese , Engenharia Metabólica/métodos , Fotossíntese/fisiologia , Synechococcus/genética , Synechococcus/metabolismo , Biotecnologia , Dióxido de Carbono/metabolismo , Clonagem Molecular , Tolerância a Medicamentos , Escherichia coli/genética , Etilenos/toxicidade , Regulação Bacteriana da Expressão Gênica , Genes Bacterianos/genética , Instabilidade Genômica , Ácidos Cetoglutáricos/metabolismo , Liases/genética , Liases/metabolismo , Pseudomonas syringae/genética , Pseudomonas syringae/metabolismo , Synechococcus/efeitos dos fármacos , Synechococcus/crescimento & desenvolvimento , Transformação Genética
15.
Chemosphere ; 229: 589-601, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31100630

RESUMO

The study aimed to evaluate the physiological mechanisms underlying differences in metals and metalloid uptake and tolerance of two tree species cultivated in mining waste material. Two-year old Acer platanoides L. and Tilia cordata Mill. were cultivated in mining sludge characterized by high pH, salinity and an extremely high concentration of As. Both species were able to develop leaves from leafless seedlings, however, their total biomass was greatly reduced in comparison to control plants, following the severe disturbances in chlorophyll content. Phytoextraction abilities were observed for T. cordata for Ba, Nb, Rb and Se, and phytostabilisation was stated for Pd, Ru, Sc and Sm for both species, Ba and Nd for A. platonoides and Be for T. cordata only. Metal exclusion was observed for the majority of detected elements indicating an intense limitation of metal transport to photosynthetic tissue. A diversified uptake of elements was accompanied by a species-specific pattern of physiological reaction during the cultivation in sludge. Organic ligands (glutatnione and low-molecular-weight organic acids) were suppressed in A. platanoides, and enhanced biosynthesis of phenolic compounds was observed for both species, being more pronounced in T. cordata. Despite its higher accumulation of key metabolites for plant reaction to oxidative stress, such as phenolic acids, flavonoids and organic ligands, T. cordata exhibited relatively lower tolerance to sludge, probably due to the increased uptake and translocation rate of toxic metal/loids to aerial organs and/or restricted accumulation of salicylic acid which is known to play a decisive role in mechanisms of plant tolerance.


Assuntos
Acer/crescimento & desenvolvimento , Mineração , Poluentes do Solo/farmacocinética , Tilia/crescimento & desenvolvimento , Acer/efeitos dos fármacos , Arsênico/análise , Arsênico/farmacocinética , Biodegradação Ambiental , Clorofila/metabolismo , Metais/farmacocinética , Metais/toxicidade , Fotossíntese/efeitos dos fármacos , Fotossíntese/fisiologia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/crescimento & desenvolvimento , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Poluentes do Solo/análise , Poluentes do Solo/toxicidade , Especificidade da Espécie , Tilia/efeitos dos fármacos , Árvores/efeitos dos fármacos , Árvores/crescimento & desenvolvimento
16.
Plant Cell Rep ; 38(8): 1001-1012, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31069499

RESUMO

KEY MESSAGE: Melatonin-induced growth promotion of maize seedlings is associated with maintaining coordination between gene expressions and activities of key enzymes involved in carbon and nitrogen metabolisms. Melatonin is a pleiotropic molecule that influences many diverse actions to enhance plant growth. The effect of melatonin on maintaining a necessary balance between carbon and nitrogen metabolisms that underpins the growth process in higher plants remains unclear. In this study, the influence of melatonin on nitrogen assimilation, mitochondrial respiration, and photosynthesis, which are major pathways related with carbon and nitrogen metabolism, was investigated on the basis of the seedling growth of maize. Melatonin applications (10, 100, and 1000 µmol L-1) significantly increased the growth parameters assessed by root elongation, plant height, leaf surface area, and the contents of protein, carbohydrate, and chlorophyll in comparison to the control seedlings. They also had a strong encouraging effect on the activities and gene expressions of enzymes (nitrate reductase, nitrite reductase, glutamine synthase, glutamate 2-oxoglutarate transferase, and NADH-glutamate dehydrogenase) involved in the nitrogen assimilation process. While melatonin applications elevated nitrate and nitrite concentrations, they markedly lowered ammonium content compared to control. Similarly, the activity of citrate synthase, the first enzyme of citric acid cycle providing carbon skeleton for nitrogen assimilation, was significantly augmented by melatonin applications. Moreover, melatonin considerably upregulated the gene expressions of citrate synthase and cytochrome oxidase, an enzyme responsible for ATP production. Remarkable increments were recorded at Rubisco activity and gene expressions of Rubisco and Rubisco activase in melatonin-treated seedlings. In conclusion, all these data put together reveal that melatonin-induced growth promotion of maize seedlings resulted from its coordinating effect on carbon and nitrogen metabolisms.


Assuntos
Carbono/metabolismo , Melatonina/metabolismo , Nitrato Redutase/metabolismo , Nitrogênio/metabolismo , Plântula/metabolismo , Clorofila/metabolismo , Glutamato-Amônia Ligase/metabolismo , Fotossíntese/fisiologia , Zea mays/metabolismo
17.
Plant Cell Physiol ; 60(8): 1778-1789, 2019 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-31111929

RESUMO

The FUR (Ferric Uptake Regulator) family in Anabaena sp. PCC 7120 consists of three paralogs named FurA (Fur), FurB (Zur) and FurC (PerR). furC seems to be an essential gene in the filamentous nitrogen-fixing strain Anabaena sp. PCC 7120, suggesting that it plays a fundamental role in this organism. In order to better understand the functions of FurC in Anabaena, the phenotype of a derivative strain that overexpresses this regulator (EB2770FurC) has been characterized. The furC-overexpressing variant presented alterations in growth rate, morphology and ultrastructure, as well as higher sensitivity to peroxide than Anabaena sp. PCC 7120. Interestingly, the overexpression of furC led to reduced photosynthetic O2 evolution, increased respiratory activity, and had a significant influence in the composition and efficiency of both photosystems. Comparative transcriptional analyses, together with electrophoretic mobility shift assays allowed the identification of different genes directly controlled by FurC, and involved in processes not previously related to PerR proteins, such as the cell division gene ftsZ and the major thylakoid membrane protease ftsH. The rise in the transcription of ftsH in EB2770FurC cells correlated with reduced levels of the D1 protein, which is involved in the PSII repair cycle. Deregulation of the oxidative stress response in EB2770FurC cells led to the identification of novel FurC targets involved in the response to H2O2 through different mechanisms. These results, together with the effect of furC overexpression on the composition, stability and efficiency of the photosynthetic machinery of Anabaena, disclose novel links between PerR proteins, cell division and photosynthesis in filamentous cyanobacteria.


Assuntos
Anabaena/metabolismo , Anabaena/fisiologia , Proteínas de Bactérias/metabolismo , Fotossíntese/fisiologia , Anabaena/genética , Proteínas de Bactérias/genética , Divisão Celular/fisiologia , Estresse Oxidativo/fisiologia , Fotossíntese/genética
18.
Environ Sci Pollut Res Int ; 26(16): 16388-16395, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30982194

RESUMO

Diatoms are experiencing striking fluctuations in seawater carbonate chemistry in the natural marine environment, especially in coastal seawaters. Here, we show that the diatoms Thalassiosira weissflogii and Phaeodactylum tricornutum, which utilize different carbon acquisition mechanisms, respond differently to short-term changes in seawater carbonate chemistry. Our results showed that T. weissflogii showed significantly higher photosynthetic oxygen evolution rates than that of P. tricornutum at low levels of CO2 or HCO3-. This suggests that T. weissflogii had higher affinities for CO2 or HCO3- when their concentrations were not sufficient to support saturated growth and photosynthesis. While the activity of Rubisco in P. tricornutum positively correlated with carbonic anhydrases (CA), we observed negative relationship between Rubisco and CA activity in the diatom T. weissflogii. These contrasting physiological responses of diatoms with varied carbon acquisition mechanisms indicate different abilities to cope up with abrupt changes in seawater carbonate chemistry. We propose that the ability to respond to varying carbonate chemistry may act as one determinant of the diatom distributions and phytoplankton community structures.


Assuntos
Dióxido de Carbono , Anidrases Carbônicas/metabolismo , Diatomáceas/metabolismo , Ribulose-Bifosfato Carboxilase/metabolismo , Água do Mar/química , Carbono/metabolismo , Diatomáceas/crescimento & desenvolvimento , Diatomáceas/fisiologia , Fotossíntese/fisiologia , Fitoplâncton/metabolismo , Especificidade da Espécie
19.
Int J Mol Sci ; 20(9)2019 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-31027369

RESUMO

It is of interest how photosynthetic electron transport (PET) reactions respond to excess light energy caused by the combination of drought stress and high temperatures. Since such information is scarcely available for photosystem I (PSI), this question was explored in rice (Oryza sativa L.) plants subjected to drought stress, using culture solutions that contain poly(ethylene glycol) at different concentrations under two day/night temperature regimes. At 27/22 °C (day/night), drought stress led to the oxidation of the reaction center of the chlorophyll of PSI (P700), and also led to decreases in the quantum efficiencies of photosystem II (PSII) and PSI, and a reduction of the primary quinone electron acceptor of PSI. Such drought stress responses were wholly stimulated at 35/30 °C. These parameters were strongly correlated with each other and were minimally affected by temperature. These results indicate that the drought stress responses of the respective PET reactions are closely associated with each other in the oxidization of P700 and that such responses are stimulated at high temperatures. The underlying mechanisms of these phenomena were discussed. While P700 oxidation is thought to suppress reactive oxygen species (ROS) production, PSI photoinhibition was observed under severe stress conditions, implying that P700 oxidation is not sufficient for the protection of PSI under drought stress.


Assuntos
Clorofila/metabolismo , Oryza/metabolismo , Complexo de Proteína do Fotossistema I/metabolismo , Clorofila/genética , Transporte de Elétrons/genética , Transporte de Elétrons/fisiologia , Temperatura Alta , Oryza/genética , Fotossíntese/genética , Fotossíntese/fisiologia , Complexo de Proteína do Fotossistema I/genética
20.
Ying Yong Sheng Tai Xue Bao ; 30(4): 1170-1178, 2019 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-30994277

RESUMO

In two growing seasons of wheat (2016-2018), a field trial with Jimai 22 as test mate-rial was conducted in Shijiawangzi Village, Yanzhou City, Shandong Province. Under three nitrogen levels of 150 (N1), 180 (N2) and 210 (N3) kg·hm-2, two irrigation-fertilization methods were designed at jointing as border irrigation and broadcasting of fertilizer (W1), micro spraying irrigation and water-fertilizer integration (W2), to examine the effects of irrigation-fertilization methods on water use, photosynthetic characteristics, and dry matter accumulation and transport of wheat. The results showed that under the same nitrogen level, seven days average soil evaporation of W2 treatment in filling period was significantly lower than that of W1 treatment, and that soil water consumption in the 60-160 cm soil layer was significantly higher than that in W1 treatment. The flag leaf net photosynthetic rate, stomatal conductance and transpiration rate of W2 treatment were signi-ficantly higher than W1 treatment from 14 to 28 days after anthesis. The amount of dry matter in anthesis and maturity stage and the allocation to grain of post-anthesis assimilates of W2 treatment were significantly higher than those in W1 treatment. There was no difference in total water consumption between W2 and W1 treatments. Grain yield, water use efficiency and nitrogen use efficiency of W2 treatment were significantly higher than W1 treatment. The highest grain yield, water use efficiency and nitrogen use efficiency were obtained at the nitrogen level of 210 kg·hm-2. By comprehensive considerations, under the same nitrogen level, treatment of micro spraying irrigation and water-fertilizer integration was better than border irrigation and broadcasting of fertilizer. The W2N3 treatment under the nitrogen level of 210 kg·hm-2 and with the application of micro spraying irrigation and water-fertilizer integration at jointing was the optimal treatment to save water and fertilizer.


Assuntos
Agricultura/métodos , Fertilizantes , Triticum/fisiologia , Irrigação Agrícola , Biomassa , Nitrogênio , Fotossíntese/fisiologia , Estações do Ano
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