Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 4.176
Filtrar
1.
BMC Plant Biol ; 21(1): 368, 2021 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-34384391

RESUMO

BACKGROUND: Melatonin is considered a potential plant growth regulator to enhance the growth of plants and increase tolerance to various abiotic stresses. Nevertheless, melatonin's role in mediating stress response in different plant species and growth cycles still needs to be explored. This study was conducted to understand the impact of different melatonin concentrations (0, 50, 100, and 150 µM) applied as a soil drench to maize seedling under drought stress conditions. A decreased irrigation approach based on watering was exposed to maize seedling after drought stress was applied at 40-45% of field capacity. RESULTS: The results showed that drought stress negatively affected the growth behavior of maize seedlings, such as reduced biomass accumulation, decreased photosynthetic pigments, and enhanced the malondialdehyde and reactive oxygen species (ROS). However, melatonin application enhanced plant growth; alleviated ROS-induced oxidative damages by increasing the photosynthetic pigments, antioxidant enzyme activities, relative water content, and osmo-protectants of maize seedlings. CONCLUSIONS: Melatonin treatment also enhanced the stomatal traits, such as stomatal length, width, area, and the number of pores under drought stress conditions. Our data suggested that 100 µM melatonin application as soil drenching could provide a valuable foundation for improving plant tolerance to drought stress conditions.


Assuntos
Melatonina/farmacologia , Reguladores de Crescimento de Plantas/farmacologia , Zea mays/efeitos dos fármacos , Zea mays/crescimento & desenvolvimento , Antioxidantes/metabolismo , Biomassa , Clorofila/metabolismo , Secas , Estresse Oxidativo , Fotossíntese/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/ultraestrutura , Proteínas de Plantas/metabolismo , Estômatos de Plantas/efeitos dos fármacos , Estômatos de Plantas/ultraestrutura , Prolina/metabolismo , Espécies Reativas de Oxigênio , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Açúcares/metabolismo , Zea mays/enzimologia , Zea mays/fisiologia
2.
Int J Mol Sci ; 22(16)2021 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-34445127

RESUMO

The common ice plant (Mesembryanthemum crystallinum L.) is a facultative crassulacean acid metabolism (CAM) plant, and its ability to recover from stress-induced CAM has been confirmed. We analysed the photosynthetic metabolism of this plant during the 72-h response period following salinity stress removal from three perspectives. In plants under salinity stress (CAM) we found a decline of the quantum efficiencies of PSII (Y(II)) and PSI (Y(I)) by 17% and 15%, respectively, and an increase in nonphotochemical quenching (NPQ) by almost 25% in comparison to untreated control. However, 48 h after salinity stress removal, the PSII and PSI efficiencies, specifically Y(II) and Y(I), elevated nonphotochemical quenching (NPQ) and donor side limitation of PSI (YND), were restored to the level observed in control (C3 plants). Swelling of the thylakoid membranes, as well as changes in starch grain quantity and size, have been found to be components of the salinity stress response in CAM plants. Salinity stress induced an over 3-fold increase in average starch area and over 50% decline of average seed number in comparison to untreated control. However, in plants withdrawn from salinity stress, during the first 24 h of recovery, we observed chloroplast ultrastructures closely resembling those found in intact (control) ice plants. Rapid changes in photosystem functionality and chloroplast ultrastructure were accompanied by the induction of the expression (within 24 h) of structural genes related to the PSI and PSII reaction centres, including PSAA, PSAB, PSBA (D1), PSBD (D2) and cp43. Our findings describe one of the most flexible photosynthetic metabolic pathways among facultative CAM plants and reveal the extent of the plasticity of the photosynthetic metabolism and related structures in the common ice plant.


Assuntos
Metabolismo Ácido das Crassuláceas/genética , Mesembryanthemum/genética , Fotossíntese/genética , Estresse Salino/genética , Cloroplastos/efeitos dos fármacos , Cloroplastos/genética , Metabolismo Ácido das Crassuláceas/efeitos dos fármacos , Mesembryanthemum/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Plastídeos/efeitos dos fármacos , Plastídeos/genética , Salinidade , Estresse Salino/efeitos dos fármacos , Cloreto de Sódio/farmacologia , Amido/genética , Tilacoides/efeitos dos fármacos , Tilacoides/genética
3.
Molecules ; 26(14)2021 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-34299611

RESUMO

A set of twenty-four 3-hydroxynaphthalene-2-carboxanilides, disubstituted on the anilide ring by combinations of methoxy/methyl/fluoro/chloro/bromo and ditrifluoromethyl groups at different positions, was prepared. The compounds were tested for their ability to inhibit photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. N-(3,5-Difluorophenyl)-, N-(3,5-dimethylphenyl)-, N-(2,5-difluorophenyl)- and N-(2,5-dimethylphenyl)-3-hydroxynaphthalene-2-carboxamides showed the highest PET-inhibiting activity (IC50 ~ 10 µM) within the series. These compounds were able to inhibit PET in photosystem II. It has been found that PET-inhibiting activity strongly depends on the position of the individual substituents on the anilide ring and on the lipophilicity of the compounds. The electron-withdrawing properties of the substituents contribute towards the PET activity of these compounds.


Assuntos
Cloroplastos/efeitos dos fármacos , Naftalenos/metabolismo , Fotossíntese/efeitos dos fármacos , Spinacia oleracea/efeitos dos fármacos , Cloroplastos/metabolismo , Transporte de Elétrons/efeitos dos fármacos , Herbicidas/química , Herbicidas/metabolismo , Naftalenos/química , Complexo de Proteína do Fotossistema II/antagonistas & inibidores , Complexo de Proteína do Fotossistema II/metabolismo , Spinacia oleracea/metabolismo
4.
BMC Plant Biol ; 21(1): 331, 2021 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-34246235

RESUMO

BACKGROUND: As damage to the ecological environment continues to increase amid unreasonable amounts of irrigation, soil salinization has become a major challenge to agricultural development. Melatonin (MT) is a pleiotropic signal molecule and indole hormone, which alleviates the damage of abiotic stress to plants. MT has been confirmed to eliminate reactive oxygen species (ROS) by improving the antioxidant system and reducing oxidative damage under adversity. However, the mechanism by which exogenous MT mediates salt tolerance by regulating the photosynthetic capacity and ion balance of cotton seedlings still remains unknown. In this study, the regulatory effects of MT on the photosynthetic system, osmotic modulators, chloroplast, and anatomical structure of cotton seedlings were determined under 0-500 µM MT treatments with salt stress induced by treatment with 150 mM NaCl. RESULTS: Salt stress reduces the chlorophyll content, net photosynthetic rate, stomatal conductance, intercellular CO2 concentration, transpiration rate, PSII photochemical efficiency, PSII actual photochemical quantum yield, the apparent electron transfer efficiency, stomata opening, and biomass. In addition, it increases non-photochemical quenching. All of these responses were effectively alleviated by exogenous treatment with MT. Exogenous MT reduces oxidative damage and lipid peroxidation by reducing salt-induced ROS and protects the plasma membrane from oxidative toxicity. MT also reduces the osmotic pressure by reducing the salt-induced accumulation of Na+ and increasing the contents of K+ and proline. Exogenous MT can facilitate stomatal opening and protect the integrity of cotton chloroplast grana lamella structure and mitochondria under salt stress, protect the photosynthetic system of plants, and improve their biomass. An anatomical analysis of leaves and stems showed that MT can improve xylem and phloem and other properties and aides in the transportation of water, inorganic salts, and organic substances. Therefore, the application of MT attenuates salt-induced stress damage to plants. Treatment with exogenous MT positively increased the salt tolerance of cotton seedlings by improving their photosynthetic capacity, stomatal characteristics, ion balance, osmotic substance biosynthetic pathways, and chloroplast and anatomical structures (xylem vessels and phloem vessels). CONCLUSIONS: Our study attributes help to protect the structural stability of photosynthetic organs and increase the amount of material accumulation, thereby reducing salt-induced secondary stress. The mechanisms of MT-induced plant tolerance to salt stress provide a theoretical basis for the use of MT to alleviate salt stress caused by unreasonable irrigation, fertilization, and climate change.


Assuntos
Gossypium/metabolismo , Melatonina/metabolismo , Fotossíntese/efeitos dos fármacos , Reguladores de Crescimento de Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Estresse Salino/efeitos dos fármacos , Tolerância ao Sal/efeitos dos fármacos , Produtos Agrícolas/metabolismo
5.
Ecotoxicol Environ Saf ; 220: 112401, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34118747

RESUMO

Cadmium (Cd) is a trace element causing severe toxicity symptoms in plants, besides posing hazardous fitness issue due to its buildup in the human body through food chain. Nanoparticles (NPs) are recently employed as a novel strategy to directly ameliorate the Cd stress and acted as nano-fertilizers. The intend of the current study was to explore the effects of zinc oxide nanoparticles (ZnO-NPs; 50 mg/L) on plant growth, photosynthetic activity, elemental status and antioxidant activity in Oryza sativa (rice) under Cd (0.8 mM) stress. To this end, the rice plants are treated by Cd stress at 15 days after sowing (DAS), and the treatment was given directly into the soil. Supply of ZnO-NPs as foliar spray was given for five consecutive days from 30 to 35 DAS, and sampling was done at 45 DAS. However, rice plants supplemented with ZnO-NPs under the Cd toxicity revealed significantly increased shoot length (SL; 34.0%), root fresh weight (RFW; 30.0%), shoot dry weight (SDW; 23.07%), and root dry weight (RDW; 12.24%). Moreover, the ZnO-NPs supplement has also positive effects on photosynthesis related parameters, SPAD value (40%), chloroplast structure, and qualitatively high fluorescence observed by confocal microscopy even under Cd stress. ZnO-NPs also substantially prevented the increases of hydrogen peroxide (H2O2) and malondialdehyde (MDA) triggered by Cd. Physiological and biochemical analysis showed that ZnO-NPs increased enzymatic activities of superoxide dismutase (SOD; 59%), catalase (CAT; 52%), and proline (17%) that metabolize reactive oxygen species (ROS); these increases coincided with the changes observed in the H2O2 and MDA accumulation after ZnO-NPs application. In conclusion, ZnO-NPs application to foliage has great efficiency to improve biomass, photosynthesis, protein, antioxidant enzymes activity, mineral nutrient contents and reducing Cd levels in rice. This can be attributed mainly from reduced oxidative damage resulted due to the ZnO-NPs application.


Assuntos
Antioxidantes/metabolismo , Cádmio/efeitos adversos , Nanopartículas , Oryza/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Poluentes do Solo/efeitos adversos , Óxido de Zinco/farmacologia , Biomassa , Catalase/metabolismo , Produtos Agrícolas/efeitos adversos , Produtos Agrícolas/fisiologia , Fertilizantes , Humanos , Peróxido de Hidrogênio/metabolismo , Malondialdeído/metabolismo , Oryza/crescimento & desenvolvimento , Oryza/metabolismo , Oryza/fisiologia , Estresse Oxidativo/efeitos dos fármacos , Folhas de Planta , Solo/química , Superóxido Dismutase/metabolismo , Óxido de Zinco/administração & dosagem
6.
Molecules ; 26(11)2021 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-34070241

RESUMO

Lipoic acid (LA) and melatonin (MT) are pleiotropic molecules participating in plant stress resistance by modulating cellular biochemical changes, ion homeostasis, and antioxidant enzyme activities. However, the combined role of these two molecules in counteracting the detrimental impacts of salinity stress is still unknown. In the present study, we determined the effects of exogenous LA (0.5 µM), MT (1 µM) and their combination (LA + MT) on growth performance and biomass accumulation, photosynthetic pigments, enzymatic and non-enzymatic antioxidant activities, and ions homeostatic in canola (Brassica napus L.) seedlings under salinity stress (0, 100 mM) for 40 days. The results indicate that exogenous application of LA + MT improved the phenotypic growth (by 25 to 45%), root thickness (by 68%), number of later lateral roots (by 52%), root viability (by 44%), and root length (by 50%) under salinity stress. Moreover, total soluble protein, chlorophyll pigments, the concentration of superoxide dismutase (SOD), catalase peroxidase (CAT), and ascorbic peroxidase (ASA) increased with the presence of salt concentration into the growth media and then decreased with the addition of LA + MT to saline solution. Leaf protein contents and the degradation of photosynthetic pigments were lower when LA + MT treatments were added into NaCl media. The proline and phenol contents decreased in the exogenous application of LA + MT treatments more than individual LA or MT treatments under the salinity stress. The incorporation of LA or MT or a combination of LA + MT to saline solution decreased salinity-induced malondialdehyde and electrolyte leakage. In conclusion, the alteration of metabolic pathways, redox modulation, and ions homeostasis in plant tissues by the combined LA and MT application are helpful towards the adaptation of Brassica napus L. seedlings in a saline environment. The results of this study provide, for the first time, conclusive evidence about the protective role of exogenous LA + MT in canola seedlings under salinity stress.


Assuntos
Brassica napus/crescimento & desenvolvimento , Produtos Agrícolas/crescimento & desenvolvimento , Melatonina/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Raízes de Plantas/efeitos dos fármacos , Estresse Salino , Ácido Tióctico/farmacologia , Antioxidantes/metabolismo , Biomassa , Brassica napus/metabolismo , Produtos Agrícolas/metabolismo , Homeostase , Malondialdeído/metabolismo , Minerais/metabolismo , Fenóis/metabolismo , Fotossíntese/efeitos dos fármacos , Pigmentos Biológicos/metabolismo , Folhas de Planta/metabolismo , Raízes de Plantas/crescimento & desenvolvimento
7.
Ecotoxicol Environ Saf ; 220: 112369, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34090109

RESUMO

Soil salinization seriously restricts the growth and yield of soybeans. However, little information is available on the early growth stages of soybeans which are subjected to the gibberellin biosynthesis inhibitor, prohexadione-calcium (Pro-Ca). This study aimed to investigate the effects of exogenous Pro-Ca on saline-alkali stress-induced damages to photosynthesis and antioxidant defenses in soybean (Glycine max L.) seedlings. At the V3 growth stage, salt-tolerant genotype Hefeng 50 (HF50) and salt-sensitive genotype Kenfeng 16 (KF16) were subjected to 110 mmol L-1 mixed saline-alkali stress respectively, and then 100 mg L-1 Pro-Ca was sprayed on the leaves. Our results showed that saline-alkali stress accelerated the degradation of thylakoids, inhibited chlorophyll synthesis, reduced shoot dry weight, electron transfer rate (ETR), and peroxidase (POD) activity, the concentration of ascorbic acid (AsA) and soluble sugar, but enhanced the concentration of proline, hydrogen peroxide (H2O2) and the rate of superoxide radical (O2∙-) generation. Additionally, saline-alkali stress induced a lower decrease of the net photosynthetic rate (Pn), potential activity of PSII (Fv/F0), and maximum quantum yield of PSII (Fv/Fm) in salt-tolerant HF50 than in salt-sensitive KF16. Nevertheless, foliar spraying of exogenous Pro-Ca increased the chlorophyll content, Pn, Fv/F0, and Fv/Fm. These results were more prominent when Pro-Ca was applied to KF16 under saline-alkali conditions. Furthermore, exogenous application of Pro-Ca retarded the degradation of thylakoids, increased the ETR and the accumulation of AsA, soluble sugar, and proline, activated the activities of superoxide dismutase (SOD), catalase (CAT), and POD, and decreased the concentration of malondialdehyde (MDA), electrolyte leakage (EL), O2∙-, and H2O2. These results indicated that Pro-Ca could effectively protect soybean seedlings against damage from saline-alkali stress by regulating seedling phenotype, photosynthetic apparatus, antioxidant defense, and osmoregulation.


Assuntos
Álcalis/toxicidade , Antioxidantes/metabolismo , Ácidos Cetoglutáricos/farmacologia , Fotossíntese/efeitos dos fármacos , Soja/efeitos dos fármacos , Clorofila/metabolismo , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Plântula/metabolismo , Soja/crescimento & desenvolvimento , Soja/metabolismo , Estresse Fisiológico/efeitos dos fármacos , Tilacoides/metabolismo
8.
Methods Mol Biol ; 2326: 225-239, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34097272

RESUMO

As increasing application of nanoparticles, nanoparticles have been becoming a new emerging environmental pollution that attracts a lot of attention from the scientific community and also regulatory agents. In the past decade, studying the toxicity and environmental impacts of nanoparticles is becoming a hot research field and more and more researches have been published using both plant and animal system. In this chapter, using oxidized metal nanoparticles as an example, we introduce a detailed protocol for performing research on biochemical and physiological toxicity of nanoparticles in plant. We employ a hydroponics system to study phytotoxicity of nanoparticles, which makes it easier to study the impact of nanoparticles. In this chapter, we majorly focus on plant respiration and photosynthesis, root vigor as well as oxidative stress. Oxidative stress is one major physiological response to different environmental pollution, in which we present a detailed method for detecting free radical oxygen species as well as the major molecules and enzymes associating with oxidative stress, including SOD and POD. Although we introduce the methods using cotton as an example, the protocols presented in this chapter can be used almost any plant species to test the biochemical and physiological toxicity of an environmental pollution.


Assuntos
Gossypium/fisiologia , Nanopartículas/toxicidade , Fotossíntese , Folhas de Planta/fisiologia , Raízes de Plantas/fisiologia , Gossypium/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Raízes de Plantas/efeitos dos fármacos , Testes de Toxicidade/métodos
9.
Int J Mol Sci ; 22(9)2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-34062942

RESUMO

A field experiment was established to study sweet potato growth, starch dynamic accumulation, key enzymes and gene transcription in the sucrose-to-starch conversion and their relationships under six K2O rates using Ningzishu 1 (sensitive to low-K) and Xushu 32 (tolerant to low-K). The results indicated that K application significantly improved the biomass accumulation of plant and storage root, although treatments at high levels of K, i.e., 300-375 kg K2O ha-1, significantly decreased plant biomass and storage root yield. Compared with the no-K treatment, K application enhanced the biomass accumulation of plant and storage root by 3-47% and 13-45%, respectively, through promoting the biomass accumulation rate. Additionally, K application also enhanced the photosynthetic capacity of sweet potato. In this study, low stomatal conductance and net photosynthetic rate (Pn) accompanied with decreased intercellular CO2 concentration were observed in the no-K treatment at 35 DAT, indicating that Pn was reduced mainly due to stomatal limitation; at 55 DAT, reduced Pn in the no-K treatment was caused by non-stomatal factors. Compared with the no-K treatment, the content of sucrose, amylose and amylopectin decreased by 9-34%, 9-23% and 6-19%, respectively, but starch accumulation increased by 11-21% under K supply. The activities of sucrose synthetase (SuSy), adenosine-diphosphate-glucose pyrophosphorylase (AGPase), starch synthase (SSS) and the transcription of Susy, AGP, SSS34 and SSS67 were enhanced by K application and had positive relationships with starch accumulation. Therefore, K application promoted starch accumulation and storage root yield through regulating the activities and genes transcription of SuSy, AGPase and SSS in the sucrose-to-starch conversion.


Assuntos
Glucose-1-Fosfato Adenililtransferase/genética , Glucosiltransferases/genética , Raízes de Plantas/crescimento & desenvolvimento , Potássio/farmacologia , Amilopectina/genética , Amilose/genética , Fertilização/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Ipomoea batatas/crescimento & desenvolvimento , Ipomoea batatas/metabolismo , Fotossíntese/efeitos dos fármacos , Raízes de Plantas/efeitos dos fármacos , Amido/metabolismo , Sacarose/metabolismo
10.
Toxins (Basel) ; 13(5)2021 04 30.
Artigo em Inglês | MEDLINE | ID: mdl-33946501

RESUMO

Non-proteinogenic neurotoxic amino acid ß-N-methylamino-L-alanine (BMAA) is synthesized by cyanobacteria, diatoms, and dinoflagellates, and is known to be a causative agent of human neurodegenerative diseases. Different phytoplankton organisms' ability to synthesize BMAA could indicate the importance of this molecule in the interactions between microalgae in nature. We were interested in the following: what kinds of mechanisms underline BMAA's action on cyanobacterial cells in different nitrogen supply conditions. Herein, we present a proteomic analysis of filamentous cyanobacteria Nostoc sp. PCC 7120 cells that underwent BMAA treatment in diazotrophic conditions. In diazotrophic growth conditions, to survive, cyanobacteria can use only biological nitrogen fixation to obtain nitrogen for life. Note that nitrogen fixation is an energy-consuming process. In total, 1567 different proteins of Nostoc sp. PCC 7120 were identified by using LC-MS/MS spectrometry. Among them, 123 proteins belonging to different functional categories were selected-due to their notable expression differences-for further functional analysis and discussion. The presented proteomic data evidences that BMAA treatment leads to very strong (up to 80%) downregulation of α (NifD) and ß (NifK) subunits of molybdenum-iron protein, which is known to be a part of nitrogenase. This enzyme is responsible for catalyzing nitrogen fixation. The genes nifD and nifK are under transcriptional control of a global nitrogen regulator NtcA. In this study, we have found that BMAA impacts in a total of 22 proteins that are under the control of NtcA. Moreover, BMAA downregulates 18 proteins that belong to photosystems I or II and light-harvesting complexes; BMAA treatment under diazotrophic conditions also downregulates five subunits of ATP synthase and enzyme NAD(P)H-quinone oxidoreductase. Therefore, we can conclude that the disbalance in energy and metabolite amounts leads to severe intracellular stress that induces the upregulation of stress-activated proteins, such as starvation-inducible DNA-binding protein, four SOS-response enzymes, and DNA repair enzymes, nine stress-response enzymes, and four proteases. The presented data provide new leads into the ecological impact of BMAA on microalgal communities that can be used in future investigations.


Assuntos
Diamino Aminoácidos/farmacologia , Fixação de Nitrogênio/efeitos dos fármacos , Nostoc/efeitos dos fármacos , Proteínas de Bactérias/metabolismo , Bicarbonatos/metabolismo , Metabolismo dos Carboidratos/efeitos dos fármacos , Dióxido de Carbono/metabolismo , Regulação para Baixo/efeitos dos fármacos , Nitrogênio/metabolismo , Nitrogenase/metabolismo , Nostoc/metabolismo , Nostoc/fisiologia , Fosforilação/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Proteômica , Estresse Fisiológico/efeitos dos fármacos
11.
J Plant Physiol ; 261: 153427, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33940557

RESUMO

Metamitron (MET) is a fruitlet thinning compound for apple trees, needing better understanding of its action on leaf energy metabolism, depending on nighttime temperature. A trial under environmental controlled conditions was set with 'Golden Reinders' potted trees, under 25/7.5 and 25/15 °C (diurnal/nighttime temperature), with (MET, 247.5 ppm) or without (CTR) application, and considering the monitoring of photosynthetic and respiration components from day 1 (D1) to 14 (D14). Net photosynthesis (Pn) decline promoted by MET after D1 was not stomatal related. Instead, non-stomatal constraints, reflected on the photosynthetic capacity (Amax), included a clear photosystem (PS) II inhibition (but barely of PSI), as shown by severe reductions in thylakoid electron transport at PSII level, maximal (Fv/Fm) and actual (Fv'/Fm') PSII photochemical efficiencies, estimate of quantum yield of linear electron transport (Y(II)), and the rise in PSII photoinhibition status (Fs/Fm' and PIChr) and uncontrolled energy dissipation (Y(NO)). To Pn inhibition also contributed the impact in RuBisCO along the entire experiment, regardless of night temperature, here reported for the first time. Globally, MET impact on the photosynthetic parameters was usually greater under 7.5 °C, with maximal impacts between D4 and D7, probably associated to a less active metabolism at lower temperature. Cellular energy metabolism was further impaired under 7.5 °C, through moderate inhibition of NADH-dependent malate dehydrogenase (MDH) and pyruvate kinase (PK) enzymes involved in respiration, in contrast with the increase of dark respiration in MET 7.5 until D7. The lower impact on PK and MDH under 15 °C and a likely global higher active metabolism at that temperature would agree with the lowest sucrose levels in MET 15 at D4 and D7. Our findings showed that MET alters the cell energy machinery in a temperature dependent manner, affecting the sucrose balance mainly at 15 °C, justifying the observed greater thinning potential.


Assuntos
Malus/metabolismo , Fotossíntese , Folhas de Planta/metabolismo , Temperatura , Triazinas/metabolismo , Dióxido de Carbono/metabolismo , Transporte de Elétrons/efeitos dos fármacos , Malus/efeitos dos fármacos , Fotoperíodo , Fotossíntese/efeitos dos fármacos , Complexo de Proteína do Fotossistema II/metabolismo , Folhas de Planta/efeitos dos fármacos , Tilacoides/efeitos dos fármacos , Tilacoides/metabolismo , Triazinas/administração & dosagem
12.
Aquat Toxicol ; 236: 105839, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34015754

RESUMO

Selenium, an essential trace element for animals, poses a threat to all forms of life above a threshold concentration. The ubiquitously present cyanobacteria, a major photosynthetic biotic component of aquatic and other ecosystems, are excellent systems to study the effects of environmental toxicants. The molecular changes that led to beneficial or detrimental effects in response to different doses of selenium oxyanion Se(IV) were analyzed in the filamentous cyanobacterium Anabaena PCC 7120. This organism showed no inhibition in growth up to 15 mg/L sodium selenite, but above this dose i.e. 20-100 mg/L of Se(IV), both growth and photosynthesis were substantially inhibited. Along with the increased accumulation of non-protein thiols, a consistent reduction in levels of ROS was observed at 10 mg/mL dose of Se(IV). High dose of Se(IV) (above 20 mg/L) enhanced endogenous reactive oxygen species (ROS)/lipid peroxidation, and decreased photosynthetic capability. Treatment with 100 mg/L Se(IV) downregulated transcription of several photosynthesis pathways-related genes such as those encoding photosystem I and II proteins, phycobilisome rod-core linker protein, phycocyanobilin, phycoerythrocyanin-associated proteins etc. Interestingly, at a dose range of 10-15 mg/L Se(IV), Anabaena showed an increase in PSII photosynthetic yield and electron transport rate (at PSII), suggesting improved photosynthesis. Se was incorporated into the Anabaena cells, and Se-enriched thylakoid membranes showed higher redox conductivity than the thylakoid membranes from untreated cells. Overall, the data supports that modulation of photosynthetic machinery is one of the crucial mechanisms responsible for the dose-dependent contrasting effect of Se(IV) observed in Anabaena.


Assuntos
Venenos de Cnidários/toxicidade , Anabaena/metabolismo , Cianobactérias/metabolismo , Ecossistema , Transporte de Elétrons , Oxirredução , Fotossíntese/efeitos dos fármacos , Complexo de Proteína do Fotossistema I/metabolismo , Ficobilinas , Ficocianina , Espécies Reativas de Oxigênio/metabolismo , Poluentes Químicos da Água/toxicidade
13.
Aquat Toxicol ; 236: 105866, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34052718

RESUMO

Herbicides are among the most detected pesticides in coastal environments. Herbicides may impact non-target organisms, but invertebrates that have a symbiotic relationship with microalgae (zooxanthellae) may be particularly susceptible. How zooxanthellae influence the response of organisms to herbicides, however, remains untested. We exposed zooxanthellate and azooxanthellate Cassiopea xamachana medusae to environmentally relevant concentrations of the herbicide atrazine (0 µg L - 1, 7 µg L - 1 and 27 µg L - 1) for 20 days. We hypothesised that atrazine would have adverse effects on the size, rate of bell contractions and, respiration of medusae, but that effects would be more severe in zooxanthellate than azooxanthellate medusae. We also predicted that photosynthetic efficiency, chlorophyll a (Chla) content and zooxanthellae density would decrease in zooxanthellate medusae exposed to atrazine. Both zooxanthellate and azooxanthellate medusae shrank, yet the size-specific respiration rates were not constant during the experiment. Photosynthetic efficiency of zooxanthellate medusae significantly decreased at 7 and 27 µgL-1 atrazine, but atrazine did not affect the Chla content or zooxanthellae density. Our results showed that even though atrazine inhibited photosynthesis, zooxanthellae were not expelled from the host. We conclude that the presence of zooxanthellae did not increase the susceptibility of C. xamachana medusae to atrazine.


Assuntos
Herbicidas/toxicidade , Cifozoários/fisiologia , Poluentes Químicos da Água/toxicidade , Animais , Atrazina , Clorofila A , Microalgas , Fotossíntese/efeitos dos fármacos , Cifozoários/efeitos dos fármacos , Simbiose
14.
Aquat Toxicol ; 236: 105840, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33945909

RESUMO

In this study, effects of polystyrene microplastics (MPS) on Euglena gracilis were investigated via examination on its photosynthesis and motility, two typical properties of the protozoan. No adverse effects were observed after 4-d exposure except for decrease in motility at two high MPS concentrations (5 and 25 mg/L). After 8-d duration, MPS at 1 mg/L had no obvious effects on E. gracilis, but two higher concentrations (5 and 25 mg/L) of MPS inhibited protozoan growth, motility, and photosynthesis. The reduced protozoan photosynthetic activity was reflected by changes in Fv/Fm (the maximum photochemical yield of PSII), ΔFIP (difference between FP and FI) and PIABS (the performance index), indicative of reduced quantum yield of electron transport and enhanced energy dissipation. A dose-dependent effect of MPS on E. gracilis was found in protozoan growth, photosynthesis and motility, especially photosynthetic indices. MPS of small size (75 nm) seemed more toxic to the protozoa than large size (1000 nm). Internalization of MPS in the cells and chloroplasts was observed clearly for the first time, likely responsible for their toxicity. Analysis on photosynthetic process and motility of E. gracilis could provide more comprehensive understanding of MPS toxicity in the aquatic environment, and may potentially serve as a biomonitoring tool.


Assuntos
Microplásticos/toxicidade , Poliestirenos/toxicidade , Poluentes Químicos da Água/toxicidade , Transporte de Elétrons , Euglena gracilis/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Plásticos/toxicidade
15.
J Virol ; 95(12)2021 05 24.
Artigo em Inglês | MEDLINE | ID: mdl-33827953

RESUMO

Sweet potato virus disease (SPVD), caused by synergistic infection of Sweet potato chlorotic stunt virus (SPCSV) and Sweet potato feathery mottle virus (SPFMV), is responsible for substantial yield losses all over the world. However, there are currently no approved treatments for this severe disease. The crucial role played by RNase III of SPCSV (CSR3) as an RNA silencing suppressor during the viruses' synergistic interaction in sweetpotato makes it an ideal drug target for developing antiviral treatment. In this study, high-throughput screening (HTS) of small molecular libraries targeting CSR3 was initiated by a virtual screen using Glide docking, allowing the selection of 6,400 compounds out of 136,353. We subsequently developed and carried out kinetic-based HTS using fluorescence resonance energy transfer technology, which isolated 112 compounds. These compounds were validated with dose-response assays including kinetic-based HTS and binding affinity assays using surface plasmon resonance and microscale thermophoresis. Finally, the interference of the selected compounds with viral accumulation was verified in planta In summary, we identified five compounds belonging to two structural classes that inhibited CSR3 activity and reduced viral accumulation in plants. These results provide the foundation for developing antiviral agents targeting CSR3 to provide new strategies for controlling sweetpotato virus diseases.IMPORTANCE We report here a high-throughput inhibitor identification method that targets a severe sweetpotato virus disease caused by coinfection with two viruses (SPCSV and SPFMV). The disease is responsible for up to 90% yield losses. Specifically, we targeted the RNase III enzyme encoded by SPCSV, which plays an important role in suppressing the RNA silencing defense system of sweetpotato plants. Based on virtual screening, laboratory assays, and confirmation in planta, we identified five compounds that could be used to develop antiviral drugs to combat the most severe sweetpotato virus disease.


Assuntos
Antivirais/farmacologia , Crinivirus/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Ipomoea batatas/virologia , Doenças das Plantas/virologia , Ribonuclease III/antagonistas & inibidores , Bibliotecas de Moléculas Pequenas/farmacologia , Antivirais/química , Antivirais/metabolismo , Crinivirus/enzimologia , Crinivirus/fisiologia , Relação Dose-Resposta a Droga , Avaliação Pré-Clínica de Medicamentos , Inibidores Enzimáticos/química , Inibidores Enzimáticos/metabolismo , Ensaios de Triagem em Larga Escala , Simulação de Acoplamento Molecular , Fotossíntese/efeitos dos fármacos , Interferência de RNA , Ribonuclease III/química , Ribonuclease III/metabolismo , Bibliotecas de Moléculas Pequenas/química , Proteínas Virais/antagonistas & inibidores
16.
J Photochem Photobiol B ; 219: 112186, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33892284

RESUMO

Harmful algal blooms in inland waters are widely linked to excess phosphorus (P) loading, but increasing evidence shows that their growth and formation can also be influenced by nitrogen (N) and iron (Fe). Deficiency in N, P, and Fe differentially affects cellular photosystems and is manifested as changes in photosynthetic yield (Fv/Fm). While Fv/Fm has been increasingly used as a rapid and convenient in situ gauge of nutrient deficiency, there are few rigorous comparisons of instrument sensitivity and ability to resolve specific nutrient stresses. This study evaluated the application of Fv/Fm to cyanobacteria using controlled experiments on a single isolate and tested three hypotheses: i) single Fv/Fm measurements taken with different PAM fluorometers can distinguish among limitation by different nutrients, ii) measurements of Fv/Fm made by the addition of DCMU are comparable to PAM fluorometers, and iii) dark adaptation is not necessary for reliable Fv/Fm measurements. We compared Fv/Fm taken from the bloom-forming Microcystis aeruginosa (UTEX LB 3037) grown in nutrient-replete treatment (R) and N-, P-, and Fe-limited treatments (LN, LP, LFe, respectively), using three pulse-amplitude modulated (PAM) fluorometers and the chemical photosynthesis inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), and evaluated the effects of dark adaptation prior to PAM measurement. There were significant differences in Fv/Fm estimates among PAM fluorometers for light- versus dark-adapted cell suspensions over the whole experiment (21 days), which were all significantly higher than the DCMU-based measurements. However, dark adaptation had no effect on Fv/Fm when comparing PAM-based values across a single nutrient treatment. All Fv/Fm methods could distinguish LN and LP from R and LFe treatments but none were able to resolve LFe from R, or LN from LP cultures. These results indicated that for most PAM applications, dark adaptation is not necessary, and furthermore that single measurements of Fv/Fm do not provide a robust measurement of nutrient limitation in Microcystis aeruginosa UTEX LB 3037, and potentially other, common freshwater cyanobacteria.


Assuntos
Fluorometria/métodos , Microcystis/metabolismo , Nutrientes/química , Clorofila/química , Diurona/farmacologia , Proliferação Nociva de Algas/efeitos dos fármacos , Proliferação Nociva de Algas/efeitos da radiação , Ferro/química , Luz , Microcystis/crescimento & desenvolvimento , Microcystis/efeitos da radiação , Nitrogênio/química , Nutrientes/farmacologia , Fósforo/química , Fotossíntese/efeitos dos fármacos , Fotossíntese/efeitos da radiação
17.
Int J Mol Sci ; 22(6)2021 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-33803866

RESUMO

Understanding the effect of extreme temperatures and elevated air (CO2) is crucial for mitigating the impacts of the coffee industry. In this work, leaf transcriptomic changes were evaluated in the diploid C. canephora and its polyploid C. arabica, grown at 25 °C and at two supra-optimal temperatures (37 °C, 42 °C), under ambient (aCO2) or elevated air CO2 (eCO2). Both species expressed fewer genes as temperature rose, although a high number of differentially expressed genes (DEGs) were observed, especially at 42 °C. An enrichment analysis revealed that the two species reacted differently to the high temperatures but with an overall up-regulation of the photosynthetic machinery until 37 °C. Although eCO2 helped to release stress, 42 °C had a severe impact on both species. A total of 667 photosynthetic and biochemical related-DEGs were altered with high temperatures and eCO2, which may be used as key probe genes in future studies. This was mostly felt in C. arabica, where genes related to ribulose-bisphosphate carboxylase (RuBisCO) activity, chlorophyll a-b binding, and the reaction centres of photosystems I and II were down-regulated, especially under 42°C, regardless of CO2. Transcriptomic changes showed that both species were strongly affected by the highest temperature, although they can endure higher temperatures (37 °C) than previously assumed.


Assuntos
Dióxido de Carbono/farmacologia , Coffea/genética , Diploide , Regulação da Expressão Gênica de Plantas , Poliploidia , Temperatura , Transcriptoma/genética , Coffea/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Ontologia Genética , Genótipo , Fotossíntese/efeitos dos fármacos , Transcriptoma/efeitos dos fármacos
18.
Toxins (Basel) ; 13(4)2021 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-33924256

RESUMO

Microplastics (MP) widely distributed in aquatic environments have adverse effects on aquatic organisms. Currently, the impact of MP on toxigenic red tide microalgae is poorly understood. In this study, the strain of Alexandrium pacificum ATHK, typically producing paralytic shellfish toxins (PST), was selected as the target. Effects of 1 and 0.1 µm polystyrene MP with three concentration gradients (5 mg L-1, 25 mg L-1 and 100 mg L-1) on the growth, chlorophyll a (Chl a), photosynthetic activity (Fv/Fm) and PST production of ATHK were explored. Results showed that the high concentration (100 mg L-1) of 1 µm and 0.1 µm MP significantly inhibited the growth of ATHK, and the inhibition depended on the size and concentration of MP. Contents of Chl a showed an increase with various degrees after MP exposure in all cases. The photosynthesis indicator Fv/Fm of ATHK was significantly inhibited in the first 11 days, then gradually returned to the level of control group at day 13, and finally was gradually inhibited in the 1 µm MP treatments, and promotion or inhibition to some degree also occurred at different periods after exposure to 0.1 µm MP. Overall, both particle sizes of MP at 5 and 25 mg L-1 had no significant effect on cell toxin quota, and the high concentration 100 mg L-1 significantly promoted the PST biosynthesis on the day 7, 11 and 15. No significant difference occurred in the cell toxin quota and the total toxin content in all treatments at the end of the experiment (day 21). All MP treatments did not change the toxin profiles of ATHK, nor did the relative molar percentage of main PST components. The growth of ATHK, Chl a content, Fv/Fm and toxin production were not affected by MP shading. This is the first report on the effects of MP on the PST-producing microalgae, which will improve the understanding of the adverse impact of MP on the growth and toxin production of A. pacificum.


Assuntos
Dinoflagelados/efeitos dos fármacos , Toxinas Marinhas/metabolismo , Microalgas/efeitos dos fármacos , Microplásticos/toxicidade , Fotossíntese/efeitos dos fármacos , Poliestirenos/toxicidade , Intoxicação por Frutos do Mar , Poluentes Químicos da Água/toxicidade , Clorofila A/metabolismo , Dinoflagelados/crescimento & desenvolvimento , Dinoflagelados/metabolismo , Microalgas/crescimento & desenvolvimento , Microalgas/metabolismo , Fatores de Tempo
19.
Aquat Toxicol ; 235: 105818, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33838497

RESUMO

Toxicity of lanthanides is generally regarded as low, and they even have been suggested to be beneficial at low concentrations. This research was conducted to investigate effects of Lanthanum (La) on Desmodesmus quadricauda, a freshwater green microalga. The algal cultures were treated with nanomolar La concentrations under controlled environmentally relevant conditions. Intracellular localization of La was analyzed with µXRF tomography in frozen-hydrated samples. At sublethal concentration (128 nM) La was in hotspots inside the cells, while at lethal 1387 nM that led to release of other ions (K, Zn) from the cells, La filled most of the cells. La had no clear positive effects on growth or photosynthetic parameters, but increasing concentrations led to a dramatic decrease in cell counts. Chlorophyll fluorescence kinetic measurements showed that La led to the inhibition of photosynthesis. Maximal photochemical quantum yield of the PSII reaction center in dark-adapted state (Fv/Fm) decreased at > 4.3 nM La during the 2nd week of treatment. Minimum dark-adapted fluorescence quantum yield (F0) increased at > 13.5 nM La during the 2nd week of treatment except for control (0.2 nM La, baseline from chemicals) and 0.3 nM La. NPQ at the beginning of the actinic light phase showed significant increase for all the treatments. Metalloproteomics by HPLC-ICPMS showed that La binds to a >500 kDa soluble protein complex already in the sub-nM range of La treatments, in the low nM range to a small-sized (3 kDa) soluble peptide, and at >100 nM La additionally binds to a 1.5 kDa ligand.


Assuntos
Clorófitas/efeitos dos fármacos , Lantânio/toxicidade , Poluentes Químicos da Água/toxicidade , Clorofila/metabolismo , Clorófitas/fisiologia , Fluorescência , Lantânio/metabolismo , Fotossíntese/efeitos dos fármacos , Complexo de Proteína do Fotossistema II/efeitos dos fármacos , Complexo de Proteína do Fotossistema II/metabolismo , Folhas de Planta/metabolismo
20.
Int J Mol Sci ; 22(7)2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33916236

RESUMO

Understanding the complex mechanisms involved in plant response to nanoparticles (NPs) is indispensable in assessing the environmental impact of nano-pollutants. Plant leaves can directly intercept or absorb NPs deposited on their surface; however, the toxicity mechanisms of NPs to plant leaves are unclear. In this study, lettuce leaves were exposed to copper oxide nanoparticles (CuO-NPs, 0, 100, and 1000 mg/L) for 15 days, then physiological tests and transcriptomic analyses were conducted to evaluate the negative impacts of CuO-NPs. Both physiological and transcriptomic results demonstrated that CuO-NPs adversely affected plant growth, photosynthesis, and enhanced reactive oxygen species (ROS) accumulation and antioxidant system activity. The comparative transcriptome analysis showed that 2270 and 4264 genes were differentially expressed upon exposure to 100 and 1000 mg/L CuO-NPs. Gene expression analysis suggested the ATP-binding cassette (ABC) transporter family, heavy metal-associated isoprenylated plant proteins (HIPPs), endocytosis, and other metal ion binding proteins or channels play significant roles in CuO-NP accumulation by plant leaves. Furthermore, the variation in antioxidant enzyme transcript levels (POD1, MDAR4, APX2, FSDs), flavonoid content, cell wall structure and components, and hormone (auxin) could be essential in regulating CuO-NPs-induced stress. These findings could help understand the toxicity mechanisms of metal NPs on crops, especially NPs resulting from foliar exposure.


Assuntos
Cobre/toxicidade , Nanopartículas Metálicas/toxicidade , Fotossíntese/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Transcriptoma/efeitos dos fármacos , Antioxidantes/metabolismo , Parede Celular/efeitos dos fármacos , Alface , Folhas de Planta/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...