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1.
Food Chem ; 335: 127621, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-32738533

RESUMO

In the present study, the effects of blue LED light on the regreening of citrus fruit were investigated in an in vitro system of Valencia orange flavedos. The results showed that blue LED light irradiation induced regreening in the flavedos. After four-week culture in vitro, the flavedos exhibited obviously green color in the blue LED light treatment, while the flavedos in the control were still in orange color. During the regreening process, the blue LED light treatment induced chlorophyll accumulation, and substantially altered the carotenoid composition in the flavedos. Compared with the control, the content of 9-cis-violaxanthin was decreased, while the contents of lutein, ß-carotene, and all-trans-violaxanthin were increased by blue LED light. In addition, gene expression results showed that the up-regulation of CitLCYe and down-regulation of CitLCYb2 by blue LED light led to a shift from ß,ß-branch to ß,ε-branch of the carotenoid biosynthetic pathway.


Assuntos
Citrus sinensis/metabolismo , Citrus sinensis/efeitos da radiação , Luz , Pigmentação/efeitos da radiação , Carotenoides/metabolismo , Clorofila/metabolismo , Citrus/metabolismo , Frutas/metabolismo , Frutas/efeitos da radiação , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Xantofilas/metabolismo , beta Caroteno/metabolismo
2.
PLoS One ; 15(10): e0239737, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33044972

RESUMO

Different densities have a great influence on the physiological process and growth of orchard plants. Exploring the molecular basis and revealing key candidate genes for different densities management of orchard has great significance for production capacity improvement. In this study, transcriptome sequencing of apple trees was carried out at three different sampling heights to determine gene expression patterns under high density(HD) and low density(LD) and the physiological indices were measured to determine the effect of density change on plants. As a result, physiological indexes showed that the content of Chlorophyll, ACC, RUBP and PEP in the LD was apparently higher than that in control group(high density, HD). While the content of PPO and AO in the LD was noticeably lower than that in the HD. There were 3808 differentially expressed genes (DEGs) were detected between HD and LD, of which 1935, 2390 and 1108 DEGs were found in the three comparisons(middle-upper, lower-outer and lower-inner), respectively. 274 common differentially expressed genes (co-DEGs) were contained in all three comparisons. Functional enrichment and KEGG pathway analysis found these genes were involved in Carbon fixation in photosynthetic organisms, Circadian rhythm, Photosynthesis - antenna proteins, Photosynthesis, chlorophyll metabolism, Porphyrin, sugar metabolism and so on. Among these genes, LHCB family participated in photosynthesis as parts of photosystem II. In addition, SPA1, rbcL, SNRK2, MYC2, BSK, SAUR and PP2C are involved in Circadian rhythm, the expression of genes related to glycometabolism and hormone signaling pathway is also changed. The results revealed that the decrease of plant density changed the photosynthetic efficiency of leaves and the expression of photosynthesis-related genes, which provide a theoretical basis for the actual production regulation of apples.


Assuntos
Malus/genética , Malus/metabolismo , Fotossíntese/fisiologia , Clorofila/metabolismo , Perfilação da Expressão Gênica/métodos , Regulação da Expressão Gênica de Plantas/genética , Folhas de Planta/metabolismo , Transcriptoma/genética
3.
Plant Mol Biol ; 104(4-5): 529-548, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32876816

RESUMO

KEY MESSAGE: This research provides comprehensive insight into the molecular networks and molecular mechanisms underlying D. officinale flower development. Flowers are complex reproductive organs and play a crucial role in plant propagation, while also providing sustenance for insects and natural bioactive metabolites for humans. However, knowledge about gene regulation and floral metabolomes in flowers is limited. In this study, we used an important orchid species (Dendrobium officinale), whose flowers can be used to make herbal tea, to perform transcriptome sequencing and metabolic profiling of early- and medium-stage flower buds, as well as opened flowers, to provide comprehensive insight into the molecular mechanisms underlying flower development. A total of 8019 differentially expressed genes (DEGs) and 239 differentiated metabolites were found. The transcription factors that were identified and analyzed belong exclusively to the MIKC-type MADS-box proteins and auxin responsive factors that are known to be involved in flower development. The expression of genes involved in chlorophyll and carotenoid biosynthesis strongly matched the metabolite accumulation patterns. The genes related to flavonoid and polysaccharide biosynthesis were active during flower development. Interestingly, indole-3-acetic acid and abscisic acid, whose trend of accumulation was inverse during flower development, may play an important role in this process. Collectively, the identification of DEGs and differentiated metabolites could help to illustrate the regulatory networks and molecular mechanisms important for flower development in this orchid.


Assuntos
Dendrobium/crescimento & desenvolvimento , Dendrobium/genética , Dendrobium/metabolismo , Flores/crescimento & desenvolvimento , Ácido Abscísico/metabolismo , Carotenoides/metabolismo , Clorofila/metabolismo , Flavonoides/metabolismo , Flores/genética , Flores/metabolismo , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Ácidos Indolacéticos/metabolismo , Proteínas de Domínio MADS/genética , Filogenia , Proteínas de Plantas/genética , Polissacarídeos/metabolismo
4.
Chemosphere ; 258: 127337, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32947656

RESUMO

The experiment was designed to evaluate the roles of Rhizophagus irregularis on chlorophyll fluorescence and chromium bioaccumulation in a grass species (Brachiaria mutica) by supplementing Cr+6 at different concentrations. Arbuscular Mycorrhizal Fungi (AMF) association facilitated lessening of chromium level in contaminated soil and enhanced chromium bioavailability in Brachiaria mutica. The mycorrhizal inoculated increased the chlorophyll (0.925 mg/g), carotenoid (0.127 mg/g), protein (2.883 mg/g), proline (0.889 mg/g) contents and activities of antioxidant enzymes like catalase, ascorbate peroxidase and glutathione peroxidase. The mycorrhizal inoculated plants also showed enhanced overall photosynthetic performance (PIϕ = 2.473) and enhanced PS-II to PS-I electron transport as evident from yield parameter (0.712) and TR0/RC (2.419) for 60 mg/kg Cr+6 treatment. The observations suggest that AMF association could defend the plants from chromium stress by elevating the number of antioxidants in plants. Rhizophagus irregularis was found to maintain a successful symbiotic relationship with Brachiaria mutica in chromium contaminated soil. The observations recommended that Rhizophagus irregularis in association with Brachiaria mutica would be an innovative approach for decontamination of Cr+6.


Assuntos
Biodegradação Ambiental , Brachiaria/metabolismo , Cromo/metabolismo , Poluentes do Solo/metabolismo , Antioxidantes/metabolismo , Bioacumulação , Clorofila/metabolismo , Cromo/análise , Glomeromycota/metabolismo , Micorrizas/metabolismo , Fotossíntese , Plantas/metabolismo , Poaceae/metabolismo , Solo , Poluentes do Solo/análise , Simbiose
5.
Ecotoxicol Environ Saf ; 203: 111054, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32888616

RESUMO

Quinclorac (3,7-dichloroquinoline-8-carboxylic acid, QNC) is a highly selective auxin herbicide that is typically applied to paddy rice fields. Its residue is a serious problem in crop rotations. In this study, Oryza sativa L. seedlings was used as a model plant to explore its biochemical response to abiotic stress caused by QNC and nZVI coexposure, as well as the interactions between QNC and nZVI treatments. Exposure to 5 and 10 mg/L QNC reduced the fresh biomass by 26.6% and 33.9%, respectively, compared to the control. The presence of 50 and 250 mg/L nZVI alleviated the QNC toxicity, but the nZVI toxicity was aggravated by the coexist of QNC. Root length was enhanced upon exposure to low or medium doses of both QNC and nZVI, whereas root length was inhibited under high-dose coexposure. Both nZVI and QNC, either alone or in combination, significantly inhibited the biosynthesis of chlorophyll, and the inhibition rate increased with elevated nZVI and QNC concentration. It was indicated that nZVI or QNC can affect the plant photosynthesis, and there was a significant interaction between the two treatments. Effects of QNC on the antioxidant response of Oryza sativa L. differed in the shoots and roots; generally, the introduction of 50 and 250 mg/L nZVI alleviated the oxidative stress (POD in shoots, SOD and MDA in roots) induced by QNC. However, 750 mg/kg nZVI seriously damaged Oryza sativa L. seedlings, which likely resulted from active iron deficiency. QNC could be removed from the culture solution by nZVI; as a result, nZVI suppressed QNC uptake by 20%-30%.


Assuntos
Antioxidantes/metabolismo , Ferro/toxicidade , Nanopartículas/toxicidade , Oryza/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Quinolinas/toxicidade , Poluentes do Solo/toxicidade , Transporte Biológico , Biomassa , Clorofila/metabolismo , Relação Dose-Resposta a Droga , Interações Medicamentosas , Oryza/crescimento & desenvolvimento , Oryza/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Plântula/metabolismo
6.
Ecotoxicol Environ Saf ; 205: 111350, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32961487

RESUMO

Atmospheric nitrogen dioxide (NO2) negatively affects plant (crop) growth and development, as well the yield and quality in some regions or environments. Arbuscular mycorrhizal fungus (AMF)-mediated amelioration of NO2-induced plant damage has been reported, but the underlying mechanisms remained unclear. This study explored the beneficial effect of AMF symbiosis on tomato plant responses to NO2 at physiology, biochemistry, and gene expression, with an emphasis on nitrate metabolism, antioxidative defense, and photosynthetic performance. Pot-grown plants were used in the experiments, which were performed in laboratory from February to November 2019. NO2 fumigation with a dose of 10 ± 1 ppm was carried out after 50 d of plant growth, and data were collected following 8 h of fumigation. NO2 fumigation (+NO2) and AMF inoculation (+AMF), alone and especially in combination (NO2 + AMF), increased the gene expression of nitrate- and nitrite reductase, and their enzymatic activity in leaves, such as by 61%, 27%, and 126% for the activity of nitrate reductase, and by 95%, 37%, and 188% for nitrite reductase, respectively, in +NO2, +AMF, and AMF + NO2 plants relative the control (-NO2, -AMF) levels. Following NO2 exposure, +AMF leaves displayed stronger activities of superoxide dismutase, peroxidase and catalase, and higher content of glutathione and ratio of its reduced form to oxidized form, as compared with -AMF ones. Correspondingly, lesser oxidative damage was detected in +AMF than in -AMF plants, as indicated by the contents of H2O2 and malondialdehyde, electrolyte leakage, also by in situ visualization for the formation of H2O2, superoxide anion, and dead cells. The increased antioxidative capacity in +AMF plants was correlated with enhanced expression of antioxidation-related genes. Exposure to NO2 substantially impaired photosynthetic processes in both + AMF and -AMF plants, but an obvious mitigation was observed in the former than in the latter. For example, the total chlorophyll, net photosynthetic rate, stomatal conductance, and ribulose-1,5-bisphosphate carboxylase activity were 18%, 27%, 26%, and 40% higher, respectively, in +AMF than in -AMF plants under NO2 stress. The differential photosynthetic performance was also revealed by chlorophyll fluorescence imaging. We analyzed the expression patterns of some genes related to photosynthesis and carbon metabolisms, and found that all of them exclusively presented a higher expression level in +AMF plants relative to -AMF ones under NO2 stress. Taken together, this study provided evidence that AMF symbiosis played a positively regulatory role in host plant responses to NO2, probably by increasing leaf nitrate metabolism and antioxidative defense, and maintaining the photosynthetic efficiency to some extent, wherein the transcription regulation might be a main target.


Assuntos
Lycopersicon esculentum/fisiologia , Micorrizas/fisiologia , Dióxido de Nitrogênio/toxicidade , Antioxidantes/metabolismo , Clorofila/metabolismo , Peróxido de Hidrogênio/metabolismo , Lycopersicon esculentum/metabolismo , Lycopersicon esculentum/microbiologia , Micorrizas/metabolismo , Oxirredução , Fotossíntese/fisiologia , Desenvolvimento Vegetal , Folhas de Planta/metabolismo
7.
Proc Natl Acad Sci U S A ; 117(37): 23158-23164, 2020 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-32868421

RESUMO

The recently discovered, chlorophyll-f-containing, far-red photosystem II (FR-PSII) supports far-red light photosynthesis. Participation and kinetics of spectrally shifted far-red pigments are directly observable and separated from that of bulk chlorophyll-a We present an ultrafast transient absorption study of FR-PSII, investigating energy transfer and charge separation processes. Results show a rapid subpicosecond energy transfer from chlorophyll-a to the long-wavelength chlorophylls-f/d The data demonstrate the decay of an ∼720-nm negative feature on the picosecond-to-nanosecond timescales, coinciding with charge separation, secondary electron transfer, and stimulated emission decay. An ∼675-nm bleach attributed to the loss of chl-a absorption due to the formation of a cation radical, PD1 +•, is only fully developed in the nanosecond spectra, indicating an unusually delayed formation. A major spectral feature on the nanosecond timescale at 725 nm is attributed to an electrochromic blue shift of a FR-chlorophyll among the reaction center pigments. These time-resolved observations provide direct experimental support for the model of Nürnberg et al. [D. J. Nürnberg et al., Science 360, 1210-1213 (2018)], in which the primary electron donor is a FR-chlorophyll and the secondary donor is chlorophyll-a (PD1 of the central chlorophyll pair). Efficient charge separation also occurs using selective excitation of long-wavelength chlorophylls-f/d, and the localization of the excited state on P720* points to a smaller (entropic) energy loss compared to conventional PSII, where the excited state is shared over all of the chlorin pigments. This has important repercussions on understanding the overall energetics of excitation energy transfer and charge separation reactions in FR-PSII.


Assuntos
Clorofila/metabolismo , Transferência de Energia/fisiologia , Fotossíntese/fisiologia , Complexo de Proteína do Fotossistema II/metabolismo , Transporte de Elétrons/fisiologia , Cinética , Luz , Análise Espectral/métodos
8.
PLoS One ; 15(9): e0238530, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32915830

RESUMO

Chlorophyll content is an important indicator of the growth status of japonica rice. The objective of this paper is to develop an inversion model that can predict japonica rice chlorophyll content by using hyperspectral image of rice canopy collected with unmanned aerial vehicle (UAV). UAV-based hyperspectral remote sensing can provide timely and cost-effective monitoring of chlorophyll content over a large region. The study was based on hyperspectral data collected at the Shenyang Agricultural College Academician Japonica Rice Experimental Base in 2018 and 2019. In order to extract the salient information embedded in the high-dimensional hyperspectral data, we first perform dimension reduction by using a successive projection algorithm (SPA). The SPA extracts the characteristic hyperspectral bands that are used as input to the inversion model. The characteristic bands extracted by SPA are 410 nm, 481 nm, 533 nm, 702 nm, and 798 nm, respectively. The inversion model is developed by using an extreme learning machine (ELM), the parameters of which are optimized by using particle swarm optimization (PSO). The PSO-ELM algorithm can accurately model the nonlinear relationship between hyperspectral data and chlorophyll content. The model achieves a coefficient of determination R2 = 0.791 and a root mean square error of RMSE = 8.215 mg/L. The model exhibits good predictive ability and can provide data support and model reference for research on nutrient diagnosis of japonica rice.


Assuntos
Clorofila/metabolismo , Modelos Biológicos , Oryza/metabolismo , Folhas de Planta/metabolismo , Tecnologia de Sensoriamento Remoto , Análise Espectral , Algoritmos , Estatística como Assunto
9.
Chemosphere ; 254: 126844, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32957274

RESUMO

The study aimed to evaluate the impact of iron (Fe) on the physiological and behavioural reaction of Chara tomentosa L. Fe was introduced into the environment in the form of iron chloride, the most common coagulants used in the restoration of water bodies. The investigations concerned the oxidative stress comprising phenolic compounds content, antioxidant activity and photosynthetic pigments concentration. Research was conducted as a laboratory microcosm experiment with one-off application of Fe at the level of 26.8 mg dm-3. Coagulant application caused short-term acidification, increased salinity and deterioration of light conditions. The shading resulted initially from the increase of water colour and turbidity and was followed by covering of the charophytes with a precipitated suspension. C. tomentosa did not activate defensive mechanisms to prevent the shading effect such as intensive elongation and elevated concentration of chlorophylls. Neither oxidative stress nor production of stress-specific phenolic metabolites was found. It was a result of iron coagulant toxicity, which led to cell membrane damage and leakage of cell contents to the water environment. Charophyte growth was significantly impaired, and thalli suffered numerous chlorotic and necrotic spots which extended gradually during experiment and finally caused death of specimens.


Assuntos
Carofíceas/efeitos dos fármacos , Ecossistema , Ferro/farmacologia , Fosfatos/farmacologia , Chara/efeitos dos fármacos , Carofíceas/crescimento & desenvolvimento , Precipitação Química , Clorofila/metabolismo , Ferro/toxicidade , Lagos/química , Estresse Oxidativo , Fenóis/análise , Água/química
10.
Toxicon ; 187: 214-222, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32941932

RESUMO

The potential Aflatoxin B1 (AFB1) binding Lactobacillus fermentum (LC5/a) was used for in vivo AFB1 binding and detoxification in presence of chlorophyll (CL) in male Swiss albino mice. Mice were randomly divided into seven groups. The control groups (CL, AFB1 and LC5/a) received chlorophyll (250 µg/kg b.w), AFB1 (100 µg/kg b.w) and LC5/a (1 × 108 CFU) for 21 days. The treatment group (AFB1+LC5/a) received 100 µl of lyophilized bacterial suspension (1 × 108 CFU) 2 h before the AFB1 dosage (100µg/kg b.w). The chlorophyll mice group (CL + AFB1) was given single oral dose of CL (250 µg/kg b.w) before AFB1 dosage and last mice group received the combination of CL + LC5/a before the AFB1 dosage over a period of 21 days. Ballooning of cytoplasm and necrosis in liver was evident in histopathological examination of AFB1 mice group, while, marked improvement and nearly normal histology were seen in LC5/a and CL treated mice group. The levels of AST, ALT, GST, and SOD were increased in AFB1 mice group compared to LC5/a and CL treated mice group. Elevated levels of pro-inflammatory cytokines, TNF-α, IL-12, IL-6 (324, 506, 117.25 pg/ml) were observed in AFB1 treated mice serum compared to LC5/a and CL treated mice (249.54, 322.01 and 82.35 pg/ml). Thus, Lactobacillus fermentum LC5/a has certainly sequestered AFB1 from gastrointestinal tract besides regulating the production of pro-inflammatory cytokines.


Assuntos
Aflatoxina B1/metabolismo , Clorofila/metabolismo , Lactobacillus fermentum/metabolismo , Animais , Camundongos , Probióticos
11.
Ecotoxicol Environ Saf ; 205: 111293, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32949840

RESUMO

Wastewater from printing and dyeing processes often contains aniline and high salinity, which are hazardous to aquatic species. Glycophytic plants cannot survive under high-salinity conditions, whereas halophytes grow well in such an environment. In this study, we investigated the influence of NaCl on the antioxidant level in Suaeda salsa affected by aniline stress. The seedlings showed various growth toxicity effects under different concentrations of aniline. The results showed that the effect of the aniline was more severe for the root growth compared to that for the shoot growth. Aniline exposure significantly increased the total free radicals and ·OH radicals in the plants. Suaeda salsa exposure to aniline caused oxidative stress by altering the superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) activity, which resulted in the overproduction of H2O2 and the inducement of lipid peroxidation. Analysis revealed that the malondialdehyde (MDA) content was enhanced after aniline exposure and that the chlorophyll content was significantly decreased. The results showed that aniline induced the production of free radicals and reactive oxygen species (ROS), and changed the antioxidant defense system. This ultimately resulted in oxidative damage in S. salsa; however, it was found that moderate salinity could mitigate the effects. In conclusion, salinity may alleviate the growth inhibition caused by aniline by regulating the antioxidant capacity of S. salsa.


Assuntos
Compostos de Anilina/toxicidade , Antioxidantes/metabolismo , Chenopodiaceae/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Cloreto de Sódio/farmacologia , Poluentes Químicos da Água/toxicidade , Catalase/metabolismo , Chenopodiaceae/enzimologia , Chenopodiaceae/crescimento & desenvolvimento , Clorofila/metabolismo , Espectroscopia de Ressonância de Spin Eletrônica , Peróxido de Hidrogênio/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Malondialdeído/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Salinidade , Plantas Tolerantes a Sal/efeitos dos fármacos , Plantas Tolerantes a Sal/enzimologia , Plantas Tolerantes a Sal/crescimento & desenvolvimento , Plântula/efeitos dos fármacos , Plântula/enzimologia , Plântula/crescimento & desenvolvimento , Superóxido Dismutase/metabolismo
12.
Proc Natl Acad Sci U S A ; 117(33): 19705-19712, 2020 08 18.
Artigo em Inglês | MEDLINE | ID: mdl-32747579

RESUMO

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


Assuntos
Proteínas de Bactérias/química , Cianobactérias/metabolismo , Complexo de Proteína do Fotossistema II/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Clorofila/química , Clorofila/metabolismo , Cianobactérias/química , Cianobactérias/genética , Cinética , Modelos Moleculares , Fotossíntese , Complexo de Proteína do Fotossistema II/genética , Complexo de Proteína do Fotossistema II/metabolismo
13.
Aquat Toxicol ; 227: 105588, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32861020

RESUMO

The pollution of polybrominated diphenyl ethers (PBDEs) is becoming a pressing environmental problem in aquatic environments, and its threat to aquatic organism has received much attention. In this study, Phaeodactylum tricornutum was treated with 0.8 and 4 mg L-1 2,2',4,4'-tetrabrominated biphenyl ether (BDE-47), the most toxic PBDEs, for 96 h. BDE-47 inhibited cell growth in a time- and concentration-dependent manner. Observation of cell ultrastructure suggested the damage of the chloroplasts morphology. BDE-47 also decreased the chlorophyll content and the oxygen evolution rate, and altered the performance of photosystems. Transcriptomic analysis revealed differential expression of 62 genes related to photosynthesis in BDE-47 treatments (4 mg L-1) and transcription suppression of 58 genes involved in chlorophyll synthesis, antenna proteins, oxygen evolution, electron transport and downstream carbon fixation, implying potential toxicity targets in cells. Additionally, the levels of reactive oxygen species (ROS) and lipid peroxidation increased under BDE-47 stress and were positively correlated with photosynthesis inhibition. Pretreatment with the ROS scavenger N-acetyl-l-cysteine reduced the extent of inhibition, suggesting that ROS was responsible for these effects. Another experiment with the electron transport chain inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea showed that the generation of ROS was partially blocked, primarily indicating that photosynthetic inhibition induced by BDE-47 contributed to ROS overproduction. Thus, BDE-47 inhibited the photosynthesis by down-regulating the gene expression. This change stimulated ROS production, further leading to chloroplast membrane damage to aggravate this inhibition via a feedback loop. These effects of BDE-47 had adverse outcomes on the entire physiological state and the population growth of the microalgae.


Assuntos
Diatomáceas/efeitos dos fármacos , Éteres Difenil Halogenados/toxicidade , Microalgas/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Poluentes Químicos da Água/toxicidade , Acetilcisteína/farmacologia , Clorofila/metabolismo , Diatomáceas/metabolismo , Diatomáceas/ultraestrutura , Relação Dose-Resposta a Droga , Expressão Gênica/efeitos dos fármacos , Peroxidação de Lipídeos/efeitos dos fármacos , Microalgas/metabolismo , Microalgas/ultraestrutura , Modelos Teóricos , Fotossíntese/genética
14.
Ecotoxicol Environ Saf ; 202: 110916, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800251

RESUMO

Selenium (Se) at low concentration is considered benefit element to plants. The range between optimal and toxic concentration of Se is narrow and varies among plant species. This study aimed to evaluate the phenotypic, physiological and biochemical responses of four rice genotypes (BRS Esmeralda, BRSMG Relâmpago, BRS Bonança and Bico Ganga) grown hydroponically treated with sodium selenate (1.5 mM L-1). Selenium treated plants showed a dramatically decrease of soluble proteins, chlorophylls, and carotenoids concentration, resulting in the visual symptoms of toxicity characterized as leaf chlorosis and necrosis. Selenium toxicity caused a decrease on shoot and root dry weight of rice plants. Excess Se increased the oxidative stress monitored by the levels of hydrogen peroxide and lipid peroxidation. The enzymatic antioxidant system (catalase, superoxide dismutase, and ascorbate peroxidase) increased in response to Se supply. Interestingly, primary metabolism compounds such as sucrose, total sugars, nitrate, ammonia and amino acids increased in Se-treated plants. The increase in these metabolites may indicate a defense mechanism for the osmotic readjustment of rice plants to mitigate the toxicity caused by Se. However, these metabolites were not effective to minimize the damages on phenotypic traits such as leaf chlorosis and reduced shoot and root dry weight in response to excess Se. Increased sugars profile combined with antioxidant enzymes activities can be an effective biomarkers to indicate stress induced by Se in rice plants. This study shows the physiological attributes that must be taken into account for success in the sustainable cultivation of rice in environments containing excess Se.


Assuntos
Oryza/fisiologia , Selênio/toxicidade , Poluentes do Solo/toxicidade , Antioxidantes/metabolismo , Ascorbato Peroxidases/metabolismo , Catalase/metabolismo , Clorofila/metabolismo , Peróxido de Hidrogênio/metabolismo , Hidroponia , Peroxidação de Lipídeos , Oryza/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Folhas de Planta/metabolismo , Ácido Selênico/metabolismo , Superóxido Dismutase/metabolismo
15.
Ecotoxicol Environ Saf ; 203: 111000, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32736119

RESUMO

Microplastics are identified as a great threat to marine environments. However, knowledge of their impacts on phytoplankton, especially for the diatoms is scarce. Herein, the effects of different polyvinyl chloride (PVC) microplastic concentrations and contact times (24, 48, 72 and 96 h) on the Fv/Fm and cell density of Phaeodactylum tricornutum (B255), Chaetoceros gracilis (B13) and Thalassiosira sp. (B280) were investigated to evaluate the toxic effects of microplastics on marine diatoms. The effects of PVC microplastics on the morphology of the diatoms was observed by SEM. The order of sensitivity to 1 µm PVC microplastics among three marine diatoms was B13 > B280 > B255, showing that the toxic effects varied with different microalgae species. Furthermore, the presence of a siliceous cell wall played a minimal role in protecting cells from the physical attack of PVC microplastics, with no significant difference from the common cell wall. PVC microplastics caused dose-dependent adverse effects on three marine diatoms. High PVC concentrations (200 mg/L) reduced the chlorophyll content, inhibited Fv/Fm, and affected the photosynthesis of three marine diatoms. The PVC microplastics adsorbed and caused physical damage on the structure of algal cells. Interactions between PVC microplastics and diatoms may be the probable reason for the negative effects of PVC on diatoms.


Assuntos
Diatomáceas/efeitos dos fármacos , Microplásticos/toxicidade , Cloreto de Polivinila/toxicidade , Poluentes Químicos da Água/toxicidade , Adsorção , Clorofila/metabolismo , Diatomáceas/crescimento & desenvolvimento , Diatomáceas/fisiologia , Relação Dose-Resposta a Droga , Microalgas/efeitos dos fármacos , Microalgas/crescimento & desenvolvimento , Microalgas/fisiologia , Fotossíntese/efeitos dos fármacos , Fitoplâncton/efeitos dos fármacos , Fitoplâncton/crescimento & desenvolvimento , Fitoplâncton/fisiologia , Fatores de Tempo
16.
PLoS One ; 15(8): e0237173, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32845897

RESUMO

Gentian is an important ornamental flower in Japan. The corolla of the majority of cultivated Japanese gentians have green spots, which are rarely encountered in flowers of other angiosperms. Little information is available on the functional traits of the green spots. In this study, we characterized the green spots in the Japanese gentian corolla using a number of microscopic techniques. Opto-digital microscopy revealed that a single visible green spot is composed of approximately 100 epidermal cells. The epidermal cells of a green spot formed a dome-like structure and the cell lumen contained many green structures that were granular and approximately 5 µm in diameter. The green structures emitted red autofluorescence when irradiated with 488 nm excitation light. Transmission electron microscopy revealed that the green structures contained typical thylakoids and grana, thus indicating they are chloroplasts. No grana were observed and the thylakoids had collapsed in the plastids of epidermal cells surrounding green spots. To estimate the rate of photosynthetic electron transfer of the green spots, we measured chlorophyll fluorescence using the MICROSCOPY version of an Imaging-PAM (pulse-amplitude-modulated) fluorometer. Under actinic light of 449 µmol m-2 s-1, substantial electron flow through photosystem II was observed. Observation of green spot formation during corolla development revealed that immature green spots formed at an early bud stage and developed to maturity associated with chloroplast degradation in the surrounding epidermal cells. These results confirmed that the Japanese gentian corolla contains functional chloroplasts in restricted areas of epidermal cells and indicated that a sophisticated program for differential regulation of chloroplast formation and degradation is operative in the epidermis.


Assuntos
Flores/citologia , Flores/metabolismo , Gentiana/anatomia & histologia , Tilacoides/metabolismo , Clorofila/metabolismo , Transporte de Elétrons , Japão , Microscopia Eletrônica de Transmissão , Microscopia de Fluorescência , Fotossíntese , Complexo de Proteína do Fotossistema I/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Epiderme Vegetal/citologia , Epiderme Vegetal/metabolismo , Folhas de Planta/metabolismo
17.
Ecotoxicol Environ Saf ; 204: 111136, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32798755

RESUMO

High temperature can lead to increased production of excess light energy, thus reducing photosynthetic capacity in plants. Photosynthetic cyclic electron flow (CEF) in photosystem I (PSI) can effectively protect photosystems, but its physiological mechanism under high temperature is poorly understood. In this study, antimycin A (AA) and thenoyltrifluoroacetone (TTFA) were used to inhibit PGR5-and NDH-dependent CEF pathways, respectively, to reveal the photoprotective functions of CEF for PSII in tobacco leaves under high temperature stress (37 °C, HT). High temperatures caused decreases in maximal photochemistry efficiency (Fv/Fm) and damaged photosystem II (PSII) in tobacco leaves. Under AA inhibition of PGR5-dependent CEF, high temperature increased the fluorescence intensity of point O (Fo) in OJIP curves, i.e., the energy absorption per active reaction center (ABS/RC), the trapping rate of the reaction center (TRo/RC), and the electron transport efficiency per reaction center (ETo/RC) in tobacco leaves. High temperature induced an increase in the hydrogen peroxide content and a decrease in pigment content in tobacco leaves. Under the high temperature treatment, inhibition of PGR5-dependent CEF reduced the activities of the PSII reaction center significantly, destroyed the oxygen-evolving complex (OEC), and impeded photosynthetic electron transfer from PSII to the plastoquinone (PQ) pool in tobacco leaves. The TTFA treatment inhibited the NDH-dependent pathway under high temperature conditions, with the relative fluorescence intensity of point I (VI) decreased significantly, and the content of hydrogen peroxide and superoxide anion increased significantly. Additionally, Fo and the redox degree of the PSII donor side (Wk) increased, and pigment content decreased compared to the control, but with little change compared to high temperature treatment, indicating that the inhibition of the NDH-dependent pathway directly weakened the capacity of the PQ pool to lead to the accumulation of reactive oxygen species (ROS) in tobacco leaves. In conclusion, CEF alleviated damage to the photosynthetic apparatus in tobacco leaves by increasing PSII heat dissipation, reducing ROS production, and maintaining the stability of the PQ pool to accommodate photosynthetic electron flow.


Assuntos
Temperatura Alta , Fotossíntese/fisiologia , Complexo de Proteína do Fotossistema I/metabolismo , Tabaco/metabolismo , Clorofila/metabolismo , Transporte de Elétrons , Elétrons , Fluorescência , Oxirredução , Complexo de Proteína do Fotossistema II/metabolismo , Folhas de Planta/metabolismo , Temperatura , Tabaco/fisiologia
18.
PLoS One ; 15(8): e0238173, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32853293

RESUMO

Damage to grasses and cereals by phloem-feeding herbivores is manifest as nutrient and chlorophyll loss, desiccation, and a gradual decline in host vigour. Chlorophyll loss in particular leads to a succession of colour changes before eventual host death. Depending on the attacking herbivore species, colour changes can be difficult to detect with the human eye. This study used digital images to examine colour changes of rice seedlings during feeding by the brown planthopper, Nilaparvata lugens (Stål) and whitebacked planthopper, Sogatella furcifera (Horváth). Values for red (580 nm), green (540 nm) and blue (550 nm) reflectance for 39 rice varieties during seedling seed-box tests were derived from images captured with a digital camera. Red and blue reflectance gradually increased as herbivore damage progressed until final plant death. Red reflectance was greater from plants attacked by the brown planthopper than plants attacked by the whitebacked planthopper, which had proportionately more green and blue reflectance, indicating distinct impacts by the two planthoppers on their hosts. Analysis of digital images was used to discriminate variety responses to the two planthoppers. Ordination methods based on red-green-blue reflectance and vegetation indices such as the Green Leaf Index (GLI) that included blue reflectance were more successful than two-colour indices or indices based on hue, saturation and brightness in discriminating between damage responses among varieties. We make recommendations to advance seed-box screening methods for cereal resistance to phloem feeders and demonstrate how images from digital cameras can be used to improve the quality of data captured during high-throughput phenotyping.


Assuntos
Oryza/fisiologia , Oryza/parasitologia , Plântula/fisiologia , Plântula/parasitologia , Animais , Clorofila/metabolismo , Hemípteros/patogenicidade , Oryza/metabolismo , Fenótipo , Floema/metabolismo , Floema/parasitologia , Floema/fisiologia , Plântula/metabolismo
19.
Aquat Toxicol ; 226: 105559, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32652412

RESUMO

High nitrate (NO3--N) concentration is a growing aquatic risk concern worldwide. However, adverse effects of high NO3--N concentration on submerged macrophytes-epiphytic biofilms are unclear. In this study, the alterations in physiological changes, biofilms formation and chemical compositions were investigated on leaves of Vallisneria asiatica exposed to different NO3--N concentrations. The findings showed that 10 mg L-1NO3--N resulted in low photosynthetic efficiency by inhibiting chlorophyll content 26.2 % and decreased intrinsic efficiency of photosystem II significantly at 14th day post treatment. Malondialdehyde, several antioxidant enzyme activities (i.e., superoxide dismutase, peroxidase and catalase), and secondary metabolites (i.e., phenolic compounds and anthocyanin) were all significantly up-regulated with 10 mg L-1NO3--N, implied oxidative stress were stimulated. However, no significant alterations in these indicators were observed with 5 mg L-1NO3--N. Compared to control, 10 mg L-1NO3--N concentration significantly stimulated microbes growth in biofilm and reduced the roughness of leaf-biofilms surface, but it had little effect on the biofilms distribution (from single clone to blocks) as revealed by scanning electron microscope and multifractal analysis. Results from X-ray photoelectron spectroscopy analysis showed that the percentage of P, Cl, K and the ratio of O1 (-O-) /O2 (C = O) were higher in leaves of control than treatments with 10 mg L-1NO3--N, indicating that 10 mg L-1NO3--N concentration exhibited significant inhibition of chemical activity and nutrient uptake of the leaf surfaces. Overall, these results demonstrated that high NO3--N does stimulate the biofilm growth and can cause negative impacts on submerged macrophytes growth.


Assuntos
Biofilmes/crescimento & desenvolvimento , Hydrocharitaceae/efeitos dos fármacos , Nitratos/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Biofilmes/efeitos dos fármacos , Catalase/metabolismo , Clorofila/metabolismo , Hydrocharitaceae/crescimento & desenvolvimento , Hydrocharitaceae/metabolismo , Hydrocharitaceae/microbiologia , Malondialdeído/metabolismo , Peroxidases/metabolismo , Fotossíntese/efeitos dos fármacos , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Folhas de Planta/microbiologia , Superóxido Dismutase/metabolismo
20.
Chemosphere ; 259: 127410, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32615455

RESUMO

Arsenic (As) can be present naturally in groundwater from peanut fields, constituting a serious problem, as roots can accumulate and mobilize the metalloid to their edible parts. Understanding the redox changes in the legume exposed to As may help to detect potential risks to human health and recognize tolerance mechanisms. Thirty-days old peanut plants inoculated with Bradyrhizobium sp. strains (SEMIA6144 or C-145) were exposed to a realistic arsenate concentration, in order to unravel the redox response and characterize the oxidative stress indexes. Thus, root anatomy, reactive oxygen species detection by fluorescence microscopy and, ROS histochemical staining along with the NADPH oxidase activity were analyzed. Besides, photosynthetic pigments and damage to lipids and proteins were determined as oxidative stress indicators. Results showed that at 3 µM AsV, the cross-section areas of peanut roots were augmented; NADPH oxidase activity was significantly increased and O2˙¯and H2O2 accumulated in leaves and roots. Likewise, an increase in the lipid peroxidation and protein carbonyls was also observed throughout the plant regardless the inoculated strain, while chlorophylls and carotenes were increased only in those inoculated with Bradyrhizobium sp. C-145. Interestingly, the oxidative burst, mainly induced by the NADPH oxidase activity, and the consequent oxidative stress was strain-dependent and organ-differential. Additionally, As modifies the root anatomy, acting as a possibly first defense mechanism against the metalloid entry. All these findings allowed us to conclude that the redox response of peanut is conditioned by the rhizobial strain, which contributes to the importance of effectively formulating bioinoculants for this crop.


Assuntos
Arachis/microbiologia , Arsênico/toxicidade , Bradyrhizobium/fisiologia , Estresse Oxidativo/fisiologia , Arachis/efeitos dos fármacos , Arachis/metabolismo , Arachis/fisiologia , Arseniatos , Arsênico/metabolismo , Bradyrhizobium/efeitos dos fármacos , Bradyrhizobium/metabolismo , Clorofila/metabolismo , Peróxido de Hidrogênio/metabolismo , Peroxidação de Lipídeos , Oxirredução , Raízes de Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Simbiose/efeitos dos fármacos
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