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1.
BMC Plant Biol ; 22(1): 255, 2022 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-35606722

RESUMO

BACKGROUND: Biogenic metallic nanoparticles have been emerging as a promising alternative for the control of phytopathogens and as nanofertilizers. In this way, it is essential to investigate the possible impacts of these new nanomaterials on plants. In this study, the effects of soil contamination with biogenic silver (AgNPs) and iron (FeNPs) with known antifungal potential were investigated on morphological, physiological and biochemical parameters of soybean seedlings. RESULTS: The exposure of plants/seedlings to AgNPs induced the reduction of root dry weight followed by oxidative stress in this organ, however, adaptive responses such as a decrease in stomatal conductance without impacts on photosynthesis and an increase in intrinsic water use efficiency were also observed. The seedlings exposed to FeNPs had shown an increase in the levels of oxygen peroxide in the leaves not accompanied by lipid peroxidation, and an increase in the expression of POD2 and POD7 genes, indicating a defense mechanism by root lignification. CONCLUSION: Our results demonstrated that different metal biogenic nanoparticles cause different effects on soybean seedlings and these findings highlight the importance of investigating possible phytotoxic effects of these nanomaterials for the control of phytopathogens or as nanofertilizers.

2.
Ecotoxicol Environ Saf ; 225: 112713, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34478983

RESUMO

Despite the important role played by nitric oxide (NO) in plants subjected to abiotic stress, NO donors application to induce drought tolerance in neotropical tree seedlings has not yet been tested. It is also worth investigating whether NO bioactivity in drought-stressed seedlings could be potentiated by NO donors nanoencapsulation. The aim of the current study is to evaluate the effects of chitosan nanoparticles (NPs) containing S-nitroso-mercaptosuccinic acid (S-nitroso-MSA) on drought-stressed seedlings of neotropical tree species Heliocarpus popayanensis Kunth in comparison to free NO donor and NPs loaded with non-nitrosated MSA. Nanoencapsulation slowed down NO release from S-nitroso-MSA, and nanoencapsulated S-nitroso-MSA yielded 2- and 1.6-fold higher S-nitrosothiol levels in H. popayanensis roots and leaves, respectively, than the free NO donor. S-nitroso-MSA has prevented drought-induced CO2 assimilation inhibition, regardless of nanoencapsulation, but the nanoencapsulated NO donor has induced earlier ameliorative effect. Both NO and MSA have decreased oxidative stress in H. popayanensis roots, but this effect was not associated with antioxidant enzyme induction, with higher seedling biomass, or with proline and glycine betaine accumulation. Nanoencapsulated S-nitroso-MSA was the only formulation capable of increasing leaf relative water content in drought-stressed plants (from 32.3% to 60.5%). In addition, it induced root hair formation (increase by 36.6% in comparison to well-hydrated plants). Overall, results have evidenced that nanoencapsulation was capable of improving the protective effect of S-nitroso-MSA on H. popayanensis seedlings subjected to drought stress, a fact that highlighted the potential application of NO-releasing NPs to obtain drought-tolerant tree seedlings for reforestation programs.


Assuntos
Quitosana , Plântula , Secas , Óxido Nítrico , Doadores de Óxido Nítrico/farmacologia , Fotossíntese , Folhas de Planta
3.
Physiol Plant ; 172(4): 2226-2237, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34096625

RESUMO

Environmental conditions influence the use of different nitrogen (N) sources by plants. We hypothesized that an increase in light intensity favors the use of nitrate (NO3 - ) relative to ammonium (NH4 + ) by seedlings of neotropical tree species from different functional groups, that is, Cecropia pachystachya (a shade-intolerant species), Cariniana estrellensis (a shade-tolerant canopy species), and Guarea kunthiana (a shade-tolerant understory species). We analyzed the growth and N metabolism in seedlings simultaneously provided with NH4 + and NO3 - , under lower (LL) and higher (HL) light intensity. 15 N incorporation into amino acids was monitored after incubation with 15 N-labeled NH4 + or NO3 - . Under HL, all species showed decreased leaf area ratio, and increased growth, nitrate reductase activity and assimilated N content. Cecropia pachystachya increased the use of both N sources under HL, with substantial increases in 15 N-amino acids derived from 15 NO3 - (12.5- and 4.0-fold in roots and leaves, respectively) and 15 NH4 + (4.5- and 3.0-fold in roots and leaves, respectively). Guarea kunthiana showed the greatest plasticity in N use, as the assimilation of 15 NO3 - in roots and leaves increased substantially under HL (11.2- and 17.0-fold, respectively). Cariniana estrellensis increased the assimilation of 15 NH4 + in roots and 15 NO3 - in leaves under HL. Therefore, the responses of N use strategies to light intensity varied with the species according to their ecological characteristics.


Assuntos
Compostos de Amônio , Árvores , Nitratos , Nitrogênio , Folhas de Planta , Raízes de Plantas , Plântula
4.
J Hazard Mater ; 418: 126350, 2021 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-34130159

RESUMO

Nanoparticles loaded with atrazine show weed control efficacy even with lower application doses of the active ingredient. Changes in the mode of action of the herbicide through the nanoformulation are key to understanding the efficiency of post-emergence activity of nanoatrazine. Here, we report the leaf absorption and translocation of nanoatrazine and atrazine employing radiometric techniques and compare their herbicidal effects in greenhouse and field conditions. Compared to the commercial formulation, nanoatrazine showed greater and faster absorption rates in mustard leaves (40% increment in the absorbed herbicide 24 h after application), inducing higher inhibition of photosystem II activity. Assays with fusicoccin-treated leaves indicated that the stomatal uptake of nanoparticles might be involved in the improved activity of nanoatrazine. Nanoencapsulation potentiated the post-emergent herbicidal activity of atrazine and the gain provided by nanoencapsulation was higher in the field compared to greenhouse conditions. Regardless of the dose, nanoatrazine provided two-fold higher weed control in the field compared to commercial atrazine. Thus, the design of this carrier system enables improvements in the performance of the herbicide in the field with less risk of environmental losses of the active ingredients due to faster absorption.


Assuntos
Atrazina , Herbicidas , Nanopartículas , Atrazina/toxicidade , Herbicidas/toxicidade , Polímeros , Controle de Plantas Daninhas
5.
J Exp Bot ; 72(3): 885-903, 2021 02 11.
Artigo em Inglês | MEDLINE | ID: mdl-33245760

RESUMO

Light drives photosynthesis and informs plants about their surroundings. Regarded as a multifunctional signaling molecule in plants, nitric oxide (NO) has been repeatedly demonstrated to interact with light signaling cascades to control plant growth, development and metabolism. During early plant development, light-triggered NO accumulation counteracts negative regulators of photomorphogenesis and modulates the abundance of, and sensitivity to, plant hormones to promote seed germination and de-etiolation. In photosynthetically active tissues, NO is generated at distinct rates under light or dark conditions and acts at multiple target sites within chloroplasts to regulate photosynthetic reactions. Moreover, changes in NO concentrations in response to light stress promote plant defenses against oxidative stress under high light or ultraviolet-B radiation. Here we review the literature on the interaction of NO with the complicated light and hormonal signaling cascades controlling plant photomorphogenesis and light stress responses, focusing on the recently identified molecular partners and action mechanisms of NO in these events. We also discuss the versatile role of NO in regulating both photosynthesis and light-dependent stomatal movements, two key determinants of plant carbon gain. The regulation of nitrate reductase (NR) by light is highlighted as vital to adjust NO production in plants living under natural light conditions.


Assuntos
Óxido Nítrico , Reguladores de Crescimento de Plantas , Luz , Nitrato Redutase , Desenvolvimento Vegetal , Plantas
6.
Bull Environ Contam Toxicol ; 105(4): 553-558, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32918155

RESUMO

The aim of this study was to evaluate, through nonlinear regression models, the initial development of soybean (Glycine max L. Merr. cv. BRS 257) in soil supplemented with different copper levels. The experiment was performed in a greenhouse under natural light and temperature conditions. The seeds were sowed in soil containing different copper levels (11.20, 32.28, 52.31, 64.51, 79.42, 117.70, 133.53, 144.32, or 164.00 mg kg- 1). Germination percentage was not affected by the increase of copper content in the soil, but there was a delay in the germination process. There was no influence of copper levels on the seedling emergence speed index until 98.42 mg kg- 1; however, higher copper amounts reduced this parameter. Low copper concentrations increased plant development, but higher concentrations compromised mainly root growth. Overall, these results suggest that copper supplementation in the soil exerted dose-dependent dual effects on soybean seedlings.


Assuntos
Cobre/efeitos adversos , Germinação/efeitos dos fármacos , Poluentes do Solo/efeitos adversos , Soja/efeitos dos fármacos , Relação Dose-Resposta a Droga , Dinâmica não Linear , Análise de Regressão , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Solo/química , Soja/crescimento & desenvolvimento
7.
Planta ; 251(4): 83, 2020 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-32189086

RESUMO

MAIN CONCLUSION: Plant growth-promoting bacteria association improved the enzymatic and non-enzymatic antioxidant pathways in Neotropical trees under drought, which led to lower oxidative damage and enhanced drought tolerance in these trees. Water deficit is associated with oxidative stress in plant cells and may, thus, negatively affect the establishment of tree seedlings in reforestation areas. The association with plant growth-promoting bacteria (PGPB) is known to enhance the antioxidant response of crops, but this strategy has not been tested in seedlings of Neotropical trees. We evaluated the effects of inoculation with two PGPB (Azospirillum brasilense and Bacillus sp.) on the antioxidant metabolism of Cecropia pachystachya and Cariniana estrellensis seedlings submitted to drought. We measured the activity of antioxidant enzymes and the content of non-enzymatic antioxidants in leaves, and biometrical parameters of the seedlings. In both tree species, drought decreased the activity of antioxidant enzymes and the content of non-enzymatic antioxidant compounds. For C. pachystachya, the enzymatic and non-enzymatic pathways were mostly influenced by A. brasilense inoculation, which enhanced ascorbate peroxidase (APX) and superoxide dismutase activities and positively affected the level of non-enzymatic antioxidant compounds. In C. estrellensis, A. brasilense inoculation enhanced APX activity. However, A. brasilense and Bacillus sp. inoculation had more influence on the non-enzymatic pathway, as both bacteria induced a greater accumulation of secondary compounds (such as chlorogenic acid, gallic acid, rutin and synapic acid) compared to that in non-inoculated plants under drought. For both species, PGPB improved biometrical parameters related to drought tolerance, as specific leaf area and leaf-area ratio. Our results demonstrate that PGPB induced antioxidant mechanisms in drought-stressed Neotropical trees, increasing drought tolerance. Thus, PGPB inoculation provides a biotechnological alternative to improve the success of reforestation programmes.


Assuntos
Antioxidantes/metabolismo , Desenvolvimento Vegetal , Estresse Fisiológico , Árvores/metabolismo , Ascorbato Peroxidases/metabolismo , Azospirillum brasilense/metabolismo , Cecropia (Planta)/metabolismo , Cecropia (Planta)/microbiologia , Secas , Lecythidaceae/metabolismo , Lecythidaceae/microbiologia , Estresse Oxidativo , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Raízes de Plantas/microbiologia , Plântula/metabolismo , Plântula/microbiologia , Árvores/microbiologia
8.
Environ Monit Assess ; 192(4): 232, 2020 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-32166379

RESUMO

Copper oxide nanoparticles (CuO NPs) have been extensively explored for use in agriculture. Previous studies have indicated that application of CuO NPs might be promising for development and conservation of plants, pest control, and for the recovery of degraded soils. However, depending on the applied concentration copper can cause phytotoxic effects. In this work, biosynthesized CuO NPs (using green tea extract) were evaluated on their effects on lettuce (Lactuca sativa L.) seedling growth, which were exposed at concentrations ranged between 0.2 and 300 µg mL-1. From the biosynthesized were obtained ultra-small CuO NPs (~ 6.6 nm), with high stability in aqueous suspension. Toxicity bioassays have shown that at low concentrations (up to 40 µg mL-1), CuO NPs did not affect or even enhanced the seed germination. At higher concentrations (higher than 40 µg mL-1), inhibition of seed germination and radicle growth ranging from 35 to 75% was observed. With the increase of CuO NPs concentrations, nitrite and S-nitrosothiols levels in radicles increased, whereas superoxide dismutase and total antioxidant activities decreased. The nitrite and S-nitrosothiols levels in lettuce radicles showed a direct dose response to CuO NP application, which may indicate nitric oxide-dependent signaling pathways in the plant responses. Therefore, the results demonstrated that at low concentrations (≤ 20 µg mL-1) of CuO NPs, beneficial effects are obtained from seedlings, enhancing plant growth, and the involvement of nitric oxide signaling in the phytotoxic effects induced by high concentration of this formulation. Graphical abstract.


Assuntos
Cobre , Alface , Nanopartículas Metálicas , Nanopartículas , Antioxidantes , Cobre/farmacologia , Monitoramento Ambiental , Alface/efeitos dos fármacos , Alface/crescimento & desenvolvimento , Óxido Nítrico , Plântula
9.
Sci Rep ; 9(1): 17371, 2019 11 22.
Artigo em Inglês | MEDLINE | ID: mdl-31758079

RESUMO

Polymeric nanoparticles have emerged as carrier systems for molecules that release nitric oxide (NO), a free radical involved in plant stress responses. However, to date, nanoencapsulated NO donors have not been applied to plants under realistic field conditions. Here, we verified the effects of free and nanoencapsulated NO donor, S-nitroso-mercaptosuccinic acid (S-nitroso-MSA), on growth, physiological and biochemical parameters of neotropical tree seedlings kept under full sunlight in the nursery for acclimation. S-nitroso-MSA incorporation into chitosan nanoparticles partially protected the NO donor from thermal and photochemical degradation. The application of nanoencapsulated S-nitroso-MSA in the substrate favoured the growth of seedlings of Heliocarpus popayanensis, a shade-intolerant tree. In contrast, free S-nitroso-MSA or nanoparticles containing non-nitrosated mercaptosuccinic acid reduced photosynthesis and seedling growth. Seedlings of Cariniana estrellensis, a shade-tolerant tree, did not have their photosynthesis and growth affected by any formulations, despite the increase of foliar S-nitrosothiol levels mainly induced by S-nitroso-MSA-loaded nanoparticles. These results suggest that depending on the tree species, nanoencapsulated NO donors can be used to improve seedling acclimation in the nursery.


Assuntos
Aclimatação , Nanopartículas/metabolismo , Doadores de Óxido Nítrico/administração & dosagem , Doadores de Óxido Nítrico/farmacocinética , Óxido Nítrico/farmacocinética , Plântula/metabolismo , Luz Solar , Aclimatação/efeitos dos fármacos , Aclimatação/fisiologia , Aclimatação/efeitos da radiação , Portadores de Fármacos , Composição de Medicamentos , Liberação Controlada de Fármacos , Jardins , Nanopartículas/química , Doadores de Óxido Nítrico/farmacologia , Fotossíntese/fisiologia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Folhas de Planta/efeitos da radiação , S-Nitrosotióis/administração & dosagem , S-Nitrosotióis/química , S-Nitrosotióis/farmacocinética , S-Nitrosotióis/farmacologia , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Tiomalatos/administração & dosagem , Tiomalatos/farmacocinética , Tiomalatos/farmacologia , Árvores/efeitos dos fármacos , Árvores/metabolismo , Árvores/efeitos da radiação , Clima Tropical
10.
Sci Rep ; 9(1): 7135, 2019 05 09.
Artigo em Inglês | MEDLINE | ID: mdl-31073210

RESUMO

Nanocarrier systems for the encapsulation of agrochemicals can contribute to sustainable agriculture, but few nanosystems have been developed for plant growth regulators (PGRs). The present study evaluated the effects of seed priming using alginate/chitosan (nanoALG/CS) and chitosan/tripolyphosphate (nanoCS/TPP) containing GA3 on the growth and productivity of Solanum lycopersicum cultivated under field conditions. The results demonstrated that nanocarrier systems could improve fruit production, with the productivity increasing almost 4-fold using nanoALG/CS-GA3. This pioneering study demonstrates the potential of nanocarrier systems with PGRs for applications in agriculture.


Assuntos
Alginatos/química , Quitosana/análogos & derivados , Quitosana/química , Giberelinas/farmacologia , Lycopersicon esculentum/crescimento & desenvolvimento , Reguladores de Crescimento de Plantas/farmacologia , Agricultura , Composição de Medicamentos , Difusão Dinâmica da Luz , Giberelinas/química , Lycopersicon esculentum/efeitos dos fármacos , Nanopartículas , Tamanho da Partícula , Reguladores de Crescimento de Plantas/química , Sementes/efeitos dos fármacos , Sementes/crescimento & desenvolvimento
11.
J Agric Food Chem ; 67(16): 4453-4462, 2019 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-30933503

RESUMO

Atrazine is one of the most used herbicides and has been associated with persistent surface and groundwater contamination, and novel formulations derived from nanotechnology can be a potential solution. We used poly(ε-caprolactone) nanoencapsulation of atrazine (NC+ATZ) to develop a highly effective herbicidal formulation. Detailed structural study of interaction between the formulation and Brassica juncea plants was carried out with evaluation of the foliar uptake of nanoatrazine and structural alterations induced in the leaves. Following postemergent treatment, NC+ATZ adhered to the leaf and penetrated mesophyll tissue mainly through the hydathode regions. NC+ATZ was transported directly through the vascular tissue of the leaves and into the cells where it degraded the chloroplasts resulting in herbicidal activity. Nanocarrier systems, such as the one used in this study, have great potential for agricultural applications in terms of maintenance of herbicidal activity at low concentrations and a substantial increase in the herbicidal efficacy.


Assuntos
Atrazina/química , Herbicidas/química , Mostardeira/efeitos dos fármacos , Nanopartículas/química , Atrazina/metabolismo , Atrazina/farmacologia , Composição de Medicamentos , Herbicidas/metabolismo , Herbicidas/farmacologia , Mostardeira/metabolismo , Nanopartículas/metabolismo , Nanotecnologia , Tamanho da Partícula , Plantas Daninhas/efeitos dos fármacos , Plantas Daninhas/crescimento & desenvolvimento
12.
Plant Physiol Biochem ; 130: 277-288, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30036857

RESUMO

The inoculation of tree species with plant growth-promoting bacteria (PGPB) has emerged as an important strategy for the acclimation of seedlings by improving plant tolerance to biotic and abiotic stresses. This study aimed to evaluate the effects of inoculation with bacterial species (Azospirillum brasilense - Ab-V5, Bacillus sp., Azomonas sp. and Azorhizophillus sp.) on the growth and physiology of the Neotropical tree species Trema micrantha and Cariniana estrellensis under drought conditions. When associated with Ab-V5 and Azomonas sp., T. micrantha showed increased protein in the leaves, starch in the leaves and roots, photosynthesis, instantaneous carboxylation efficiency and root and shoot dry mass. Moreover, there were reductions in hydrogen peroxide, lipid peroxidation, water potential and proline. In C. estrellensis associated with Ab-V5, higher values of photosynthesis and instantaneous carboxylation efficiency were observed, in addition to higher starch content in the leaves and roots and higher protein content in the leaves; lower hydrogen peroxide and lipid peroxidation contents were also observed. The associations of T. micrantha with Ab-V5 and Azomonas sp. and C. estrellensis with Ab-V5 favored the activation of metabolic processes under drought, leading to greater drought tolerance. This work demonstrates the effects of compatible associations of Neotropical tree and PGPB species and suggests that the identification of compatible PGPB strains can result in tree seedlings with increased tolerance to abiotic stresses, such as drought.


Assuntos
Azospirillum brasilense/metabolismo , Bacillus/metabolismo , Lecythidaceae/fisiologia , Pseudomonadaceae/metabolismo , Plântula/fisiologia , Árvores/fisiologia , Trema/fisiologia , Desidratação , Lecythidaceae/microbiologia , Peroxidação de Lipídeos , Fotossíntese , Folhas de Planta/fisiologia , Proteínas de Plantas/metabolismo , Raízes de Plantas/fisiologia , Prolina/metabolismo , Plântula/microbiologia , Amido/metabolismo , Árvores/microbiologia , Trema/microbiologia
13.
Plant Physiol Biochem ; 114: 119-127, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28288402

RESUMO

Few studies have analyzed the strategies of neotropical tree seedlings for absorbing, translocating and assimilating the nitrogen. Here, we compared the nitrogen use strategies of seedlings from six tree species that are native to the Brazilian Atlantic Forest and that belong to different successional groups: Trema micrantha, Heliocarpus popayanensis and Cecropia pachystachya (pioneers), Cariniana estrellensis, Eugenia brasiliensis and Guarea kunthiana (non-pioneers). The effects of cultivating seedlings with nitrate or ammonium on the growth, physiology and nitrogen metabolism were analyzed. Nitrate-grown pioneer species had much higher leaf nitrate reductase activity than non-pioneer ones, but non-pioneer seedlings were also able to use nitrate as a nitrogen source. In addition to this remarkable difference between the groups in the capacity for leaf nitrate assimilation, substantial variations in the nitrogen use strategies were observed within the successional classes. Differently from the other non-pioneers, the canopy species C. estrellensis seemed to assimilate nitrate mainly in the leaves. Morphophysiological analyses showed a gradient of ammonium toxicity response, with E. brasiliensis as the most tolerant species, and T. micrantha and H. popayanensis as the most sensitive ones. Guarea kunthiana showed a relatively low tolerance to ammonium and an unusual high translocation of this cation in the xylem sap. In contrast to the other pioneers, C. pachystachya had a high plasticity in the use of nitrogen sources. Overall, these results suggest that nitrogen use strategies of neotropical tree seedlings were not determined solely by their successional position.


Assuntos
Nitrogênio/metabolismo , Plântula/metabolismo , Árvores/metabolismo , Compostos de Amônio/metabolismo , Transporte Biológico , Brasil , Clima , Ecossistema , Nitrato Redutase/metabolismo , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo , Raízes de Plantas/metabolismo , Plântula/fisiologia , Xilema/metabolismo
14.
Colloids Surf B Biointerfaces ; 150: 141-152, 2017 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-27914250

RESUMO

This work concerns the development of nanocarriers composed of alginate/chitosan (ALG/CS) and chitosan/tripolyphosphate (CS/TPP) for the plant growth regulator gibberellic acid (GA3). ALG/CS nanoparticles with and without GA3 presented mean size of 450±10nm, polydispersity index (PDI) of 0.3, zeta potential of -29±0.5mV, concentrations of 1.52×1011 and 1.92×1011 nanoparticles mL-1, respectively, and 100% encapsulation efficiency. CS/TPP nanoparticles with and without GA3 presented mean size of 195±1nm, PDI of 0.3, zeta potential of +27±3mV, concentrations of 1.92×1012 and 3.54×1012 nanoparticles mL-1, respectively, and 90% encapsulation efficiency. The nanoparticles were stable during 60days and the two systems differed in terms of the release mechanism, with the release depending on factors such as pH and temperature. Bioactivity assays using Phaseolus vulgaris showed that the ALG/CS-GA3 nanoparticles were most effective in increasing leaf area and the levels of chlorophylls and carotenoids. The systems developed showed good potential, providing greater stability and efficiency of this plant hormone in agricultural applications.


Assuntos
Quitosana/química , Portadores de Fármacos/química , Giberelinas/química , Nanopartículas/química , Reguladores de Crescimento de Plantas/química , Agricultura/métodos , Alginatos/química , Varredura Diferencial de Calorimetria , Carotenoides/química , Clorofila/química , Concentração de Íons de Hidrogênio , Cinética , Luz , Microscopia de Força Atômica , Modelos Teóricos , Tamanho da Partícula , Phaseolus/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Polímeros/química , Polifosfatos/química , Espalhamento de Radiação , Solubilidade , Temperatura
15.
PLoS One ; 10(7): e0132971, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26186597

RESUMO

Poly(epsilon-caprolactone) (PCL) nanocapsules have been recently developed as a modified release system for atrazine, an herbicide that can have harmful effects in the environment. Here, the post-emergence herbicidal activity of PCL nanocapsules containing atrazine was evaluated using mustard (Brassica juncea) as target plant species model. Characterization of atrazine-loaded PCL nanocapsules by nanoparticle tracking analysis indicated a concentration of 7.5 x 10(12) particles mL(-1) and an average size distribution of 240.7 nm. The treatment of mustard plants with nanocapsules carrying atrazine at 1 mg mL(-1) resulted in a decrease of net photosynthesis and PSII maximum quantum yield, and an increase of leaf lipid peroxidation, leading to shoot growth inhibition and the development of severe symptoms. Time course analysis until 72 h after treatments showed that nanoencapsulation of atrazine enhanced the herbicidal activity in comparison with a commercial atrazine formulation. In contrast to the commercial formulation, ten-fold dilution of the atrazine-containing nanocapsules did not compromise the herbicidal activity. No effects were observed when plants were treated with nanocapsules without herbicide compared to control leaves sprayed with water. Overall, these results demonstrated that atrazine-containing PCL nanocapsules provide very effective post-emergence herbicidal activity. More importantly, the use of nanoencapsulated atrazine enables the application of lower dosages of the herbicide, without any loss of efficiency, which could provide environmental benefits.


Assuntos
Atrazina/toxicidade , Herbicidas/toxicidade , Mostardeira/efeitos dos fármacos , Nanocápsulas/química , Biomassa , Gases/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Tamanho da Partícula , Complexo de Proteína do Fotossistema II/metabolismo , Folhas de Planta/efeitos dos fármacos , Brotos de Planta/efeitos dos fármacos , Poliésteres/química , Teoria Quântica
16.
Amino Acids ; 46(4): 1121-9, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24468931

RESUMO

Carbon (C) and nitrogen (N) metabolism are integrated processes that modulate many aspects of plant growth, development, and defense. Although plants with deficient N metabolism have been largely used for the elucidation of the complex network that coordinates the C and N status in leaves, studies at the whole-plant level are still lacking. Here, the content of amino acids, organic acids, total soluble sugars, starch, and phenylpropanoids in the leaves, roots, and floral buds of a nitrate reductase (NR) double-deficient mutant of Arabidopsis thaliana (nia1 nia2) were compared to those of wild-type plants. Foliar C and N primary metabolism was affected by NR deficiency, as evidenced by decreased levels of most amino acids and organic acids and total soluble sugars and starch in the nia1 nia2 leaves. However, no difference was detected in the content of the analyzed metabolites in the nia1 nia2 roots and floral buds in comparison to wild type. Similarly, phenylpropanoid metabolism was affected in the nia1 nia2 leaves; however, the high content of flavonol glycosides in the floral buds was not altered in the NR-deficient plants. Altogether, these results suggest that, even under conditions of deficient nitrate assimilation, A. thaliana plants are capable of remobilizing their metabolites from source leaves and maintaining the C-N status in roots and developing flowers.


Assuntos
Arabidopsis/metabolismo , Carbono/metabolismo , Nitratos/metabolismo , Nitrogênio/metabolismo , Arabidopsis/enzimologia , Proteínas de Arabidopsis/metabolismo , Nitrato Redutase/metabolismo , Nitrato Redutases/metabolismo , Folhas de Planta/enzimologia , Folhas de Planta/metabolismo , Raízes de Plantas/enzimologia , Raízes de Plantas/metabolismo
17.
Amino Acids ; 44(2): 743-55, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22990842

RESUMO

Plants submitted to O(2) deficiency present a series of biochemical modifications, affecting overall root metabolism. Here, the effect of hypoxia on the metabolic fate of (15)N derived from (15)NO(3)(-), (15)NO(2)(-) and (15)NH(4)(+) in isolated soybean root segments was followed by gas chromatography-mass spectrometry, to provide a detailed analysis of nitrogen assimilation and amino acid biosynthesis under hypoxia. O(2) deficiency decreased the uptake of the nitrogen sources from the solution, as ratified by the lower (15)NO(3)(-) and (15)NH(4)(+) enrichment in the root segments. Moreover, analysis of endogenous NO(2)(-) and (15)NH(4)(+) levels suggested a slower metabolism of these ions under hypoxia. Accordingly, regardless of the nitrogen source, hypoxia reduced total (15)N incorporation into amino acids. Analysis of (15)N enrichment patterns and amino acid levels suggest a redirecting of amino acid metabolism to alanine and γ-aminobutyric acid synthesis under hypoxia and a differential sensitivity of individual amino acid pathways to this stress. Moreover, the role of glutamine synthetase in nitrogen assimilation both under normoxia and hypoxia was ratified. In comparison with (15)NH(4)(+), (15)NO(2)(-) assimilation into amino acids was more strongly affected by hypoxia and NO(2)(-) accumulated in root segments during this stress, indicating that nitrite reductase may be an additional limiting step. NO(2)(-) accumulation was associated with a higher nitric oxide emission. (15)NO(3)(-) led to much lower (15)N incorporation in both O(2) conditions, probably due to the limited nitrate reductase activity of the root segments. Overall, the present work shows that profound alterations of root nitrogen metabolism occur during hypoxic stress.


Assuntos
Aminoácidos/metabolismo , Nitrogênio/metabolismo , Oxigênio/metabolismo , Raízes de Plantas/metabolismo , Soja/metabolismo
18.
Biochim Biophys Acta ; 1827(3): 239-47, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23201478

RESUMO

The enzyme S-nitrosoglutathione reductase (GSNOR) has an important role in the metabolism of S-nitrosothiols (SNO) and, consequently, in the modulation of nitric oxide (NO)-mediated processes. Although the mitochondrial electron transport chain is an important target of NO, the role of GSNOR in the functionality of plant mitochondria has not been addressed. Here, we measured SNO content and NO emission in Arabidopsis thaliana cell suspension cultures of wild-type (WT) and GSNOR overexpressing (GSNOR(OE)) or antisense (GSNOR(AS)) transgenic lines, grown under optimal conditions and under nutritional stress. Respiratory activity of isolated mitochondria and expression of genes encoding for mitochondrial proteins were also analyzed. Under optimal growth conditions, GSNOR(OE) had the lowest SNO and NO levels and GSNOR(AS) the highest, as expected by the GSNO-consuming activity of GSNOR. Under stress, this pattern was reversed. Analysis of oxygen uptake by isolated mitochondria showed that complex I and external NADH dehydrogenase activities were inhibited in GSNOR(OE) cells grown under nutritional stress. Moreover, GSNOR(OE) could not increase alternative oxidase (AOX) activity under nutritional stress. GSNOR(AS) showed constitutively high activity of external NADH dehydrogenase, and maintained the activity of the uncoupling protein (UCP) under stress. The alterations observed in mitochondrial protein activities were not strictly correlated to changes in gene expression, but instead seemed to be related with the SNO/NO content, suggesting a post-transcriptional regulation. Overall, our results highlight the importance of GSNOR in modulating SNO and NO homeostasis as well mitochondrial functionality, both under normal and adverse conditions in A. thaliana cells.


Assuntos
Aldeído Oxirredutases/metabolismo , Arabidopsis/metabolismo , Mitocôndrias/metabolismo , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Linhagem Celular , Complexo I de Transporte de Elétrons/metabolismo , Proteínas Mitocondriais/metabolismo , NADH Desidrogenase/metabolismo , Óxido Nítrico/metabolismo , Oxirredutases/metabolismo , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , S-Nitrosotióis/análise
19.
Nitric Oxide ; 21(2): 132-9, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19576290

RESUMO

Mitochondria recently have emerged as important sites in controlling NO levels within the cell. In this study, the synthesis of nitric oxide (NO) from nitrite and its degradation by mitochondria isolated from Arabidopsis thaliana were examined. Oxygen and NO concentrations in the reaction medium were measured with specific electrodes. Nitrite inhibited the respiration of isolated A. thaliana mitochondria, in competition with oxygen, an effect that was abolished or potentiated when electron flow occurred via alternative oxidase (AOX) or cytochrome c oxidase (COX), respectively. The production of NO from nitrite was detected electrochemically only under anaerobiosis because of a superoxide-dependent process of NO degradation. Electron leakage from external NAD(P)H dehydrogenases contributed the most to NO degradation as higher rates of Amplex Red-detected H(2)O(2) production and NO consumption were observed in NAD(P)H-energized mitochondria. Conversely, the NO-insensitive AOX diminished electron leakage from the respiratory chain, allowing the increase of NO half-life without interrupting oxygen consumption. These results show that the accumulation of nitric oxide derived from nitrite reduction and the superoxide-dependent mechanism of NO degradation in isolated A. thaliana mitochondria are influenced by the external NAD(P)H dehydrogenases and AOX, revealing a role for these alternative proteins of the mitochondrial respiratory chain in the control of NO levels in plant cells.


Assuntos
Arabidopsis/metabolismo , Complexo III da Cadeia de Transporte de Elétrons/metabolismo , Mitocôndrias/metabolismo , NADH Desidrogenase/metabolismo , Óxido Nítrico/metabolismo , Nitritos/metabolismo , Superóxidos/metabolismo , Proteínas de Arabidopsis/metabolismo , Interpretação Estatística de Dados , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Proteínas Mitocondriais , NAD/metabolismo , NADH Desidrogenase/farmacologia , Oxirredutases/metabolismo , Oxigênio/metabolismo , Proteínas de Plantas
20.
FEBS Lett ; 583(13): 2276-80, 2009 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-19524570

RESUMO

Mitochondria consume nitric oxide (NO) mainly through reaction with superoxide anion (O(2)(-)). Here, we analyzed the O(2)(-) sources for NO degradation by isolated rat liver mitochondria. Electron leakage from complex III and reverse electron transport to complex I accounted for O(2)(-)-dependent NO degradation by mitochondria in the presence of a protonmotive force. Mitochondria incubated with NAD(P)H also presented intense O(2)(-) generation and NO degradation rates that were insensitive to respiratory inhibitors and abolished after proteinase treatment. These results suggest that an outer membrane-localized NAD(P)H oxidase activity, in addition to the electron leakage from the respiratory chain, promotes O(2)(-)-dependent NO degradation in rat liver mitochondria.


Assuntos
Mitocôndrias Hepáticas/metabolismo , NAD/metabolismo , Óxido Nítrico/metabolismo , Superóxidos/metabolismo , Animais , Masculino , NADPH Oxidases/metabolismo , Ratos , Ratos Wistar
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