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1.
J Agric Food Chem ; 67(35): 9738-9748, 2019 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-31411877

RESUMO

The presence of chromium (Cr) in cultivated fields affects carbohydrate metabolism of rice (Oryza sativa L.) and weakens its productivity. Little is known about the molecular mechanism of sucrose metabolism underlying Cr stress response in rice plants. In the present study, the transcriptome map of sucrose metabolism in rice seedlings exposed to both trivalent and hexavalent chromium was investigated using Agilent 4 × 44K rice microarray analysis. Results indicated that Cr exposure (3 days) significantly (p < 0.05) improved sucrose accumulation, and altered the activities of sucrose synthetase, sucrose phosphate phosphatase, and amylosynthease in rice tissues. We identified 119 differentially regulated genes involved in 17 sucrose metabolizing enzymes and found that gene responses in roots were significantly (p < 0.05) stronger than in shoots under both Cr(III) and Cr(VI) treatment. The network maps of gene regulation responsible for sucrose metabolism in rice plants provide a theoretical basis for further cultivating Cr-resistant rice cultivars through molecular genetic improvement.


Assuntos
Cromo/farmacologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Oryza/metabolismo , Poluentes do Solo/farmacologia , Sacarose/metabolismo , Glucosiltransferases/genética , Glucosiltransferases/metabolismo , Oryza/efeitos dos fármacos , Oryza/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/genética , Raízes de Plantas/metabolismo
2.
World J Microbiol Biotechnol ; 35(8): 117, 2019 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-31332532

RESUMO

Iron- and sulfur-oxidizing bacteria inhabiting rice rhizoplane play a significant role on arsenic biogeochemistry in flooded rice paddies, influencing arsenic translocation to rice grains. In the present study, the selective pressure of arsenic species on these microbial populations was evaluated. Rice roots from continuously flooded plants were incubated in iron sulfide (FeS) gradient tubes and exposed to either arsenate or arsenite. The biomass developed in the visible iron-oxidation band of the enrichments was analyzed by Scanning Electron Microscopy and Energy-Dispersive Spectroscopy (SEM-EDS) and the bacterial communities were characterized by 16S rRNA gene sequencing. Different Proteobacteria communities were selected depending on exposure to arsenate and arsenite. Arsenate addition favored the versatile iron-oxidizers Dechloromonas and Azospira, associated to putative iron (hydr)oxide crystals. Arsenite exposure decreased the diversity in the enrichments, with the development of the sulfur-oxidizer Thiobacillus thioparus, likely growing on sulfide released by FeS. Whereas sulfur-oxidizers were observed in all treatments, iron-oxidizers disappeared when exposed to arsenite. These results reveal a strong impact of different inorganic arsenics on rhizospheric iron-oxidizers as well as a crucial role of sulfur-oxidizing bacteria in establishing rice rhizosphere communities under arsenic pressure.


Assuntos
Arsênico/metabolismo , DNA Bacteriano/isolamento & purificação , Oryza/efeitos dos fármacos , Oryza/microbiologia , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/microbiologia , Arseniatos/metabolismo , Arsenitos/metabolismo , DNA Bacteriano/genética , Ferro/metabolismo , Oxirredução , Proteobactérias/efeitos dos fármacos , Proteobactérias/isolamento & purificação , Proteobactérias/metabolismo , RNA Ribossômico 16S/genética , RNA Ribossômico 16S/isolamento & purificação , Solo/química , Microbiologia do Solo , Poluentes do Solo/metabolismo , Enxofre/metabolismo
3.
Environ Pollut ; 253: 959-965, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31351304

RESUMO

Application of Zinc (Zn) is considered an effective measure to reduce Cadmium (Cd) uptake and toxicity in Cd-contaminated soils for many plant species. However, interaction between Zn and Cd in rice plant is complex and uncertain. In this study, four indica rice cultivars were selected to evaluate the effect of Zn exposure in an EGTA-buffered nutrient solution under varying Zn activities and a field level of Cd activity to characterize the interaction between Zn and Cd in rice. Severe depression in shoots' biomass, tiller number, and SPAD (Soil and Plant Analyzer Development) value were found at both Zn deficiency and Zn phytotoxicity levels among four tested rice cultivars. There existed a strong antagonism interaction between Zn and Cd in both shoot and root from Zn deficiency to Zn phytotoxicity. The reduction of Cd accumulation in roots and shoots could be explained by the competition between Zn and Cd as well as the dilution effect of increasing biomass. The conflicting effect of Zn supply on Cd uptake may be attributed to the increasing transfer ratio of Cd from root to shoot with the increasing Zn2+ activities and the strong depression of Fe and Mn in shoots with the increasing Zn2+ activities as well as the variation of genotypes. Balance between Zn and Cd should be considered in field application.


Assuntos
Cádmio/metabolismo , Oryza/fisiologia , Poluentes do Solo/metabolismo , Zinco/metabolismo , Transporte Biológico/efeitos dos fármacos , Biomassa , Cádmio/análise , Poluição Ambiental , Oryza/efeitos dos fármacos , Raízes de Plantas/efeitos dos fármacos , Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
4.
Ecotoxicol Environ Saf ; 182: 109447, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31325809

RESUMO

Methylmercury (MeHg) in rice grains grown in Hg-contaminated areas has raised environmental health concerns. Pot experiments found that selenium (Se) could reduce MeHg levels in rice grains. However, relatively high levels of Se (up to 6 mg/kg) were applied in these pot experiments, which may have adverse effects on the soil ecology due to the toxicity of Se. The aims of this work were thus to study 1) the effect of low levels of Se on the accumulation and distribution of Hg, especially MeHg, in rice plants grown in a real Hg-contaminated paddy field and 2) the effect of Se treatment on Se and other nutritional elements (e.g., Cu, Fe, Zn) in grains. A field study amended with different levels of Se was carried out in Hg-contaminated paddy soil in Qingzhen, Guizhou, China. The levels of MeHg and total Hg were studied using cold vapor atomic fluorescence spectrometry (CVAFS) and inductively coupled plasma mass spectrometry (ICP-MS). The distribution and relative quantification of elements in grains were examined by synchrotron radiation X-ray fluorescence analysis (SR-XRF). This field study showed that low levels of Se (0.5 µg/mL, corresponding to 0.15 mg Se/kg soils) could significantly reduce total Hg and MeHg in rice tissues. Se treatment also reduced Hg distribution in the embryo and endosperm and increased the levels of Fe, Cu, Zn and Se in grains and especially embryos. This field study implied that treatment with an appropriate level of Se is an effective approach to not only decrease the level of MeHg but to also increase the levels of nutritional elements such as Fe, Cu, Zn and Se in rice grains, which could bring beneficial effects for rice-dependent residents living in Hg-contaminated areas.


Assuntos
Mercúrio/análise , Compostos de Metilmercúrio/análise , Oryza/efeitos dos fármacos , Selênio/farmacologia , Poluentes do Solo/análise , China , Fazendas , Mercúrio/metabolismo , Compostos de Metilmercúrio/metabolismo , Oryza/crescimento & desenvolvimento , Oryza/metabolismo , Solo/química , Poluentes do Solo/metabolismo
5.
Environ Pollut ; 252(Pt B): 967-973, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31252135

RESUMO

Arsenic (As) in rice grains is a serious food safety concern. Some coexisting engineered nanoparticles (ENPs) were shown to alter the accumulation and speciation of As in rice grains. However, investigation on the effects of copper oxide nanoparticles (CuO NPs), a popular ingredient in pesticides, on the uptake and accumulation of As is rare. We explored the potentially different impact of CuO NPs and corresponding Cu(II) ions on the accumulation of two As species in rice seedlings in a hydroponic system. Rice seedlings were treated with a combinations of 1 mg/L of arsenite (As(III)) or arsenate (As(V)) and 100 mg/L of CuO NPs or Cu(II) for 6 days. Both forms of Cu significantly reduced the accumulation of total As in rice tissues, with Cu(II) exhibiting significantly greater effect than CuO NPs. As speciation in rice roots was markedly affected by both forms of Cu, and the impacts were Cu-form dependent. For example, the co-existence of As(V) with CuO NPs led to a 45% decrease of As(V) in rice roots, while the co-existence of As(V) with Cu(II) caused a 47% increase in As(V) in rice roots. As speciation in rice shoots was less affected by co-present Cu than in rice roots. Co-occurring As(III) or As(V) lowered Cu concentration in rice roots by 40% and 50% in treatments with CuO NPs, but did not affect Cu content in rice roots co-exposed to Cu(II). The study confirmed the reciprocal effect of co-occurring CuO NPs or Cu(II) and As in rice paddies and highlighted the unique "nano-effect" of CuO NPs. The results alsos showed that the initial oxidation state of As plays an important role in the interactions between As and Cu. The results shed light on the current debate on the safe applications of nano-enabled agrichemicals vs. conventional metal salts in agriculture.


Assuntos
Arsênico/metabolismo , Cobre/farmacologia , Nanopartículas/metabolismo , Oryza/efeitos dos fármacos , Transporte Biológico , Cobre/metabolismo , Interações de Medicamentos , Oryza/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Plântula/efeitos dos fármacos , Plântula/metabolismo
6.
Environ Sci Pollut Res Int ; 26(22): 22421-22430, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31154647

RESUMO

The synergistic effects of trace elements selenium (Se) and cadmium (Cd) are well known. But the reasons for the trending accumulation behavior in both trace elements are under debate in the scientific community. The present investigation was conducted to evaluate the impact of heat units on the accumulation behavior in two environments. Se and Cd were applied in three groups (T0; 0:0, T1; 0.4:1, T2; 1:2) mg kg-1. As the time of planting and heat units consumed by the crop to attain its physiological maturity appears to be different. The sunlight may contribute as an important manipulating factor for the accumulation of heavy metals in the plant. The results of the present study indicated that the behavior in the accumulation pattern of both elements appears to be distinct in the same material. The increased fertilizer treatment in soil bulk linearly increased the metal contents in rice grain. The studies between different plant parts disclosed panicle as the primary reservoir for Se and Cd accumulation. The plant sown earlier accumulates more Se than Cd while the plants uptake more Cd when sown 1 month later. The plant completes the critical developmental phases (tillering, heading, and flowering) within 20-30 days interval depending on the variety. But the late-sown plants complete these transitional phases within 9-10 days interval ultimately result in less utilization of heat units. These quick transitional changes may lead to the uptake of an ample amount of Cd contents in rice grain even at a low level of Cd stress (1 and 2 mg kg-1), making rice unsafe for edible purposes. The proper time of planting could be effective in timely acclimatization of Se and Cd sequestration and translocation in rice various components. Graphical Abstract.


Assuntos
Cádmio/análise , Grão Comestível/química , Fertilizantes/análise , Metais Pesados/análise , Oryza/efeitos dos fármacos , Selênio/análise , Transporte Biológico , Metais Pesados/química , Oryza/química , Selênio/química , Solo
7.
Environ Sci Pollut Res Int ; 26(24): 24979-24987, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31243656

RESUMO

Under flooded conditions in paddy soil, the mobility of As increases while the mobility of Cd decreases. The opposite geochemical behavior of As and Cd makes it difficult to reduce their mobilities simultaneously. Our recent study found that combined applications of biochar and zero-valent iron successfully reduced the mobilities of As and Cd simultaneously. On this basis, in the present study, an iron-modified biochar (Fe-BC) was developed, and its effect on decreasing the accumulations of As and Cd in rice was verified in a 2-year field trial. In addition, previous studies indicated that silicon fertilizer can also reduce As and Cd accumulation in rice grain. Hence, the effect of the combined or separate application of Fe-BC and silica sol on As and Cd accumulation in rice grain was investigated. Over the 2-year field trial, the grain yields decreased in the following order: iron-modified biochar plus silica sol (Fe-BC plus Si) > silica sol (Si) > Fe-BC > control (CK). Concentrations of As and Cd in brown rice were in the order: Fe-BC plus Si < Si ≈ Fe-BC < CK. The treatments of Fe-BC and Fe-BC plus Si significantly increased the soil pH and thus decreased available As and available Cd in the soil. In addition, significantly positive correlations between available As and As in brown rice and between available Cd and Cd in brown rice were found. In conclusion, co-application of iron-modified biochar and silica sol should be a recommended strategy to reduce the accumulation of As and Cd in rice grains.


Assuntos
Arsênico/análise , Cádmio/análise , Grão Comestível/química , Ferro/química , Oryza/efeitos dos fármacos , Dióxido de Silício/química , Silício/metabolismo , Arsênico/química , Cádmio/química , Carvão Vegetal , Poluição Ambiental/análise , Ferro/análise , Silício/farmacologia , Poluentes do Solo/análise
8.
Environ Pollut ; 252(Pt B): 1087-1096, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31252106

RESUMO

Effects of CeO2 NPs (200 mg.L-1) on rice (Oryza sativa L.) alone or co-exposure with cadmium (Cd) and salt (sodium chloride, NaCl) were investigated in hydroponic systems for two weeks. Physiological results show that rice biomass was significantly inhibited when NaCl or CdCl2 added alone or in co-exposure treatment. CeO2 NPs significantly relieve the chlorophyll damage under CdCl2 environmental stress. The presence of CeO2 NPs alleviated both stressors induced damages to rice as indicated by the reduced proline level. Additionally, CeO2 NPs triggered the antioxidant defense systems to counteract the oxidative stress caused by NaCl and CdCl2. The level of 8-OHdG, one of the most important indicators for genotoxicity, in rice suggest that the presence of CeO2 NPs reduced the DNA damage in NaCl treated rice. Elemental analysis indicated that co-exposure to NaCl and CdCl2 slightly decreased the Cd content as compared to the one in the CdCl2 alone treatment, and this co-exposure also significantly reduced the Na content when comparing with the NaCl alone treatment. Taken together, our findings suggest that CeO2 NPs could alleviate the CdCl2 and NaCl stresses, but could not completely change the phenotype of both contaminants treated rice.


Assuntos
Cádmio/toxicidade , Cério/farmacologia , Nanopartículas/química , Oryza/efeitos dos fármacos , Cloreto de Sódio/toxicidade , Poluentes do Solo/toxicidade , Antioxidantes/farmacologia , Biomassa , Cério/química , Clorofila/metabolismo , Hidroponia , Oryza/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Plântula/efeitos dos fármacos , Plântula/metabolismo
9.
Sci Total Environ ; 684: 360-370, 2019 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-31153082

RESUMO

Exposure to arsenic (As) through rice consumption potentially threatens millions of people worldwide. Understanding is still lacking the recycling impacts of rice residues on As phytoavailability in paddy soils and is of indisputable importance in providing a sustainable and effective measure to decrease As accumulation in rice grain. Herein, we examined the effects of rice husk biochar (RHB) and rice husk ash (RHA) on As grain speciation, and As dynamics in the soil porewater and solid-phase fractions. The results corroborated that both the RHB and RHA (0.64% w/w) treatments significantly (p < 0.05) decreased inorganic As accumulation in rice grain to 0.27-0.29 mg kg-1, which was below the maximum inorganic As level in husked rice (0.35 mg kg-1) established by the Codex. The residual phase (F6 = 90% of total soil As) as quantified by the sequential extraction was the dominant As pool; the fractions were subsequently transformed into several As pools associated with soluble and exchangeable (F1), organically bound (F2), Mn oxides (F3), poorly crystalline (F4) and crystalline (F5) Fe oxides during the rice growing periods. The Si-rich amendments enhanced the residual phase formation upon soil flooding, which decreased the As availability to rice plant. The inorganic grain-As concentrations were well explained by the soil-extractable As concentrations in the F2, F3, F5, and F6 fractions. The pore-water analysis indicated that Mn oxides were important sources and sinks for As released to the soil solution. Our findings shed light on the beneficial role of RHB and RHA in alleviating inorganic As uptake in paddy rice.


Assuntos
Arsenicais/análise , Carvão Vegetal/química , Cinza de Carvão/química , Oryza/efeitos dos fármacos , Silício/química , Poluentes do Solo/análise , Poluentes Químicos da Água/análise , Arsênico/análise , Arsênico/química , Arsenicais/química , Grão Comestível/química , Grão Comestível/crescimento & desenvolvimento , Grão Comestível/metabolismo , Água Subterrânea/química , Oryza/crescimento & desenvolvimento , Oryza/metabolismo , Solo/química
10.
Chemosphere ; 230: 440-448, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31121508

RESUMO

Rice-crab (Chinese mitten crab, Eriocheir sinensis) coculture system has become one of the most important agricultural activities practiced in China. However, the effect of pesticide usage on the survival and edible safety of crab species living in the coculture system has not been investigated. In the present study, we created a field simulation experiment and discovered that the amount of pesticide chlorantraniliprole (CAP) entering the rice-crab coculture system accounted for 82.22% of the total CAP content present in the spray barrel. When CAP residues found in the soil leached into nearby areas, we observed an increase in the CAP concentration in the water and sediment. Specifically, peak CAP concentration (1.35 µg/L) was detected in water within 1 day, and a steady CAP concentration in the sediment (2.55 µg/kg) was detected within 3 days. Additionally, an extensive field sampling experiment conducted in the basin of the lower reaches of the Yangtze River revealed that CAP was routinely used in rice-crab coculture systems. Although detected CAP concentrations were below 1 µg/L in ditch water and below 1 µg/kg in ditch sediment, there was still a potential risk associated with the crab growth. Importantly, there was no risk associated with crab consumption, given the low detection frequency of CAP in the collected samples. Our analysis suggests that an increase in usage ratio and a decrease in the total CAP content will likely promote safe application of CAP in the rice-crab coculture systems.


Assuntos
Agricultura/métodos , Braquiúros/efeitos dos fármacos , Oryza/efeitos dos fármacos , Praguicidas/toxicidade , Rios/química , Poluentes Químicos da Água/toxicidade , ortoaminobenzoatos/toxicidade , Animais , Braquiúros/crescimento & desenvolvimento , China , Contaminação de Alimentos/análise , Oryza/crescimento & desenvolvimento , Praguicidas/análise , Medição de Risco , Alimentos Marinhos/análise , Poluentes Químicos da Água/análise , ortoaminobenzoatos/análise
11.
Ecotoxicol Environ Saf ; 179: 160-166, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31039458

RESUMO

Non-selective cation channels (NSCCs) play important roles in uptake of heavy metals in plants. However, little information is available concerning the contribution of NSCCs to cadmium (Cd) transport in rice seedlings. Results from the hydroponic experiment showed that the inhibition of 2.7 µM Cd on the development of rice roots was alleviated by adding 0.1 mM gadolinium (Gd) in nutrient solution, companied by reduction of Cd content by 55.3% in roots and by 45.0% in shoots. Inhibition of Gd on Cd accumulation in cytoplasm fraction (F3) was much greater than that in cell walls (F1) and organelles (F2) in roots. After increasing concentrations of Mn and Zn in nutrient solution, adding 0.1 mM Gd resulted in reductions in Cd content by 89.1%, in micronutrients by 54.9% and in macronutrients by 5.4% in roots, respectively. Cd stress resulted in significant increase of PC2∼4 and free amino acids, but decrease of V-ATPase activity by 32.3% in roots. These results indicate that NSCCs make a great contribution to uptake of Cd in rice seedlings and opportunities for Cd to be transported by NSCCs can be efficiently reduced by blocking NSCCs and/or increasing essential microelements like Mn and Zn.


Assuntos
Cádmio/metabolismo , Gadolínio/farmacologia , Canais Iônicos/antagonistas & inibidores , Transporte de Íons/efeitos dos fármacos , Oryza/metabolismo , Plântula/metabolismo , Hidroponia , Oryza/efeitos dos fármacos , Oryza/crescimento & desenvolvimento , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento
12.
Int J Mol Sci ; 20(9)2019 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-31083591

RESUMO

Nitrogen (N) is an extremely important macronutrient for plant growth and development. It is the main limiting factor in most agricultural production. However, it is well known that the nitrogen use efficiency (NUE) of rice gradually decreases with the increase of the nitrogen application rate. In order to clarify the underlying metabolic and molecular mechanisms of this phenomenon, we performed an integrated analysis of the rice transcriptome and metabolome. Both differentially expressed genes (DEGs) and metabolite Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated that carbon and nitrogen metabolism is significantly affected by nitrogen availability. Further analysis of carbon and nitrogen metabolism changes in rice under different nitrogen availability showed that high N inhibits nitrogen assimilation and aromatic metabolism pathways by regulating carbon metabolism pathways such as the tricarboxylic acid (TCA) cycle and the pentose phosphate pathway (PPP). Under low nitrogen, the TCA cycle is promoted to produce more energy and α-ketoglutarate, thereby enhancing nitrogen transport and assimilation. PPP is also inhibited by low N, which may be consistent with the lower NADPH demand under low nitrogen. Additionally, we performed a co-expression network analysis of genes and metabolites related to carbon and nitrogen metabolism. In total, 15 genes were identified as hub genes. In summary, this study reveals the influence of nitrogen levels on the regulation mechanisms for carbon and nitrogen metabolism in rice and provides new insights into coordinating carbon and nitrogen metabolism and improving nitrogen use efficiency in rice.


Assuntos
Carbono/metabolismo , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Metaboloma/genética , Nitrogênio/metabolismo , Oryza/genética , Aminoácidos/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Redes Reguladoras de Genes/efeitos dos fármacos , Metaboloma/efeitos dos fármacos , Metabolômica , Nitrogênio/farmacologia , Oryza/efeitos dos fármacos , Folhas de Planta/anatomia & histologia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/fisiologia , Fatores de Transcrição/metabolismo
13.
Environ Pollut ; 252(Pt A): 171-179, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31146232

RESUMO

Organic pollutants are widely detected in surface water, groundwater and irrigation sewage in farmland soil, some of which can form complexes with heavy metal ions as ligands in the environment. Acesulfame (ACE), one of the most popular artificial sweeteners, has been found in wastewater sometimes at tens of microgram per liter. However, the combined effects of heavy metals and ACE are still unclear. In the present study, the effects of ACE on cadmium (Cd) absorption and translocation in rice seedlings (Oryza sativa L.) under different exposure conditions were investigated using hydroponic experiments. Under the combined exposure treatments of ACE and Cd, absorption of Cd and ACE in rice significantly decreased when compared with the single exposure treatments, while the alleviation of oxidative damage in rice was also found. Under the sequential exposure treatments of Cd and ACE, the post-exposed ACE activated the pre-absorbed Cd in plant, and accelerated the release of Cd to the environment as well as its translocation from the roots to shoots. In addition, compared with the single Cd exposure, the accumulated ACE can alleviate the oxidative damage in rice shoots induced by Cd, although the Cd concentrations in shoots changed little. In summary, the combined pollution of artificial sweetener ACE was beneficial to relieve the toxicological damage and ecological risk caused by Cd.


Assuntos
Biodegradação Ambiental/efeitos dos fármacos , Cádmio/metabolismo , Oryza/metabolismo , Poluentes do Solo/análise , Edulcorantes/farmacologia , Tiazinas/farmacologia , Transporte Biológico/efeitos dos fármacos , Cádmio/análise , Poluição Ambiental/análise , Hidroponia , Oryza/efeitos dos fármacos , Raízes de Plantas/efeitos dos fármacos , Plântula/efeitos dos fármacos , Solo
14.
Ecotoxicol Environ Saf ; 179: 265-271, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31059993

RESUMO

The content of gadolinium (Gd) is continuously increased in environment, which potentially threatens human health and ecological equilibrium. However, the phytotoxicity of Gd on plants remains unknown until now. In this study, the accumulation, distribution, and chemical forms of Gd as well as its influence on growth and nutrient balance were systematically studied in rice seedlings after the treatments of different concentrations of Gd (0, 1, 10, 100, and 1000 µM) for 10 days. The results showed that most Gd was accumulated in the roots and only a little percentage of Gd was transported to shoots. The accumulation of Gd was increased in a dose-dependent manner in various chemical forms and subcellular fractions. More than 80% of Gd was in the forms of insoluble oxalates and phosphates. Gd was mainly compartmentalized in the cell wall, and the content of Gd was increased with increasing concentrations of Gd. In addition, hormetic effects of Gd were found on rice growth. The growth of rice was induced by the lower concentration of Gd, but inhibited by the higher concentration of Gd. The results indicated that rice seedlings could cope with Gd toxicity through cell wall compartmentalization as well as forming of precipitates with oxalate and phosphate.


Assuntos
Gadolínio/toxicidade , Oryza/efeitos dos fármacos , Oryza/crescimento & desenvolvimento , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Poluentes do Solo/toxicidade , Análise por Conglomerados , Relação Dose-Resposta a Droga , Gadolínio/química , Gadolínio/metabolismo , Humanos , Oryza/metabolismo , Oxalatos/química , Fosfatos/química , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Plântula/metabolismo , Poluentes do Solo/química , Poluentes do Solo/metabolismo
15.
J Agric Food Chem ; 67(22): 6143-6149, 2019 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-31083983

RESUMO

Strigolactones (SLs) are one of the plant hormones that control several important agronomic traits, such as shoot branching, leaf senescence, and stress tolerance. Manipulation of the SL biosynthesis can increase the crop yield. We previously reported that a triazole derivative, TIS108, inhibits SL biosynthesis. In this study, we synthesized a number of novel TIS108 derivatives. Structure-activity relationship studies revealed that 4-(2-phenoxyethoxy)-1-phenyl-2-(1 H-1,2,4-triazol-1-yl)butan-1-one (KK5) inhibits the level of 4-deoxyorobanchol in roots more strongly than TIS108. We further found that KK5-treated Arabidopsis showed increased branching phenotype with the upregulated gene expression of AtMAX3 and AtMAX4. These results indicate that KK5 is a specific SL biosynthesis inhibitor in rice and Arabidopsis.


Assuntos
Reguladores de Crescimento de Planta/antagonistas & inibidores , Terpenos/antagonistas & inibidores , Triazóis/química , Triazóis/farmacologia , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Oryza/efeitos dos fármacos , Oryza/genética , Oryza/metabolismo , Reguladores de Crescimento de Planta/biossíntese , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Terpenos/metabolismo , Triazóis/síntese química
16.
Plant Biol (Stuttg) ; 21(5): 854-861, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30929297

RESUMO

Cadmium (Cd) is one of the most toxic heavy metals and a non-essential element to all organisms, including plants; however, the genes involved in Cd resistance in plants remain poorly characterised. To identify Cd resistance genes in rice, we screened a rice cDNA expression library treated with CdCl2 using a yeast (Saccharomyces cerevisiae) mutant ycf1 strain (DTY167) and isolated two rice phytochelatin synthases (OsPCS5 and OsPCS15). The genes were strongly induced by Cd treatment and conferred increased resistance to Cd when expressed in the ycf1 mutant strain. In addition, the Cd concentration was twofold higher in yeast expressing OsPCS5 and OsPCS15 than in vector-transformed yeast, and OsPCS5 and OsPCS15 localised in the cytoplasm. Arabidopsis thaliana plants overexpressing OsPCS5/-15 paradoxically exhibited increased sensitivity to Cd, suggesting that overexpression of OsPCS5/-15 resulted in toxicity due to excess phytochelatin production in A. thaliana. These data indicate that OsPCS5 and OsPCS15 are involved in Cd tolerance, which may be related to the relative abundances of phytochelatins synthesised by these phytochelatin synthases.


Assuntos
Aminoaciltransferases/metabolismo , Cádmio/toxicidade , Oryza/enzimologia , Proteínas de Plantas/metabolismo , Aminoaciltransferases/genética , Arabidopsis , Genes de Plantas/genética , Oryza/efeitos dos fármacos , Oryza/genética , Plantas Geneticamente Modificadas , Alinhamento de Sequência
17.
Environ Pollut ; 249: 647-654, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30933762

RESUMO

Rice grain is known to accumulate methylmercury (MeHg) and has been confirmed to be the major pathway of MeHg exposure to residents in mercury (Hg) mining areas in China. Selenium (Se) supplementation has been proven to be effective in mitigating the toxicity of Hg. To understand how Se supplementation influences soil Hg speciation, a wide range of Se (0-500 mg/kg) was applied to Hg polluted paddy soils in this study, which decreased MeHg concentration in soil from 2.95 ±â€¯0.36 to 0.69 ±â€¯0.16 µg/kg (or 77%). After Se addition, humic acid state Hg (F4) was transformed into strong-complexed state Hg (F5), indicating that Hg bound up to the non-sulfur functional groups of humic acid (non-RSH) was released and reabsorbed by strong binding Se functional group (F5). As a result, inorganic Hg (IHg) was reduced by >48%, 18%, and 80% in root, stem, and grain, respectively, however, the reduction was not apparent in leaf. Substantial reductions were also found for MeHg in grain and root, but not in stem and leaf. Soil is suggested to be the main source of both MeHg and IHg in rice grain. Such a finding may provide an idea for improving Hg-polluted paddies through controlling soil IHg and MeHg. Further research on the molecular structure of the strong-complexed Hg in F5 should be conducted to elucidate the mechanism of Hg-Se antagonism.


Assuntos
Compostos de Mercúrio/análise , Mercúrio/análise , Compostos de Metilmercúrio/análise , Oryza/efeitos dos fármacos , Selênio/química , Poluentes do Solo/análise , Transporte Biológico , China , Grão Comestível/química , Substâncias Húmicas/análise , Compostos de Mercúrio/metabolismo , Compostos de Metilmercúrio/metabolismo , Mineração , Oryza/metabolismo , Estruturas Vegetais/metabolismo , Selênio/farmacologia , Solo/química
18.
Environ Sci Pollut Res Int ; 26(16): 16220-16228, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30972675

RESUMO

Cadmium (Cd) is absorbed readily by rice plants and is transferred to humans when contaminated rice is consumed. Adding selenium (Se) to the plant nutrient solutions reduces the accumulation of Cd in the rice (Oryza sativa L.) seedlings. However, as the relevant underlying mechanism remains unclear, the aim of our study was to improve our understanding of the Se-mediated resistance to Cd stress in rice. We conducted hydroponic experiments to study the effects of selenite or selenate on Cd subcellular distribution and xylem transport in rice seedlings under Cd stress, and we investigated the antioxidative defense responses in the rice plants. We found that the supplementation of both Se forms decreased the Cd accumulations in the roots and shoots of the rice plants. The selenite addition significantly decreased the Cd contents in different subcellular fractions of the rice roots, increased the proportion of Cd distributed to soluble cytosol by 23.41%, and decreased the Cd distribution in the organelle by 28.74% in contrast with the treatment with Cd only. As regards the selenate addition, only the Cd distribution ratio of cytosol was increased by 13.07%. After adding selenite, a decrease of 55.86% in the Cd concentration in xylem sap was observed, whereas little change was found after treatment co-applied with selenate. The hydrogen peroxide (H2O2) and malondialdehyde(MDA) contents in the rice roots were elevated under Cd stress, and the addition of selenite and selenate decreased the H2O2 levels by 77.78% and 59.26%, respectively. Co-exposure to Cd and Se elevated the glutathione (GSH) accumulations in the rice shoots and roots, with the degree of increase being the following: co-applied with selenite > co-applied with selenate > Cd alone treatment. Exposure to Cd increased the catalase (CAT) activity in the roots significantly, whereas it decreased in the shoots. After selenite or selenate supplementation, the CAT activity in the rice roots increased compared with applying only Cd. Compared with the control, the addition of Cd or Se had no significant effect on the activities of peroxidase (POD) or ascorbate peroxidase (APX). Our results showed that Se affected the Cd accumulation in rice seedlings by altering the Cd subcellular distribution and decreasing the ROS induced by Cd stress. Such effects were more significant in the selenite than in the selenate applied treatment.


Assuntos
Cádmio/farmacocinética , Oryza/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Selênio/farmacologia , Antioxidantes/metabolismo , Cádmio/toxicidade , Glutationa/metabolismo , Peróxido de Hidrogênio/metabolismo , Hidroponia , Malondialdeído/farmacologia , Oryza/metabolismo , Proteínas de Plantas/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Plântula/efeitos dos fármacos , Plântula/metabolismo , Ácido Selênico/farmacologia , Ácido Selenioso/farmacologia , Distribuição Tecidual , Xilema/efeitos dos fármacos , Xilema/metabolismo
19.
Planta ; 250(1): 333-345, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31030327

RESUMO

MAIN CONCLUSION: Selenium modulates the formation of primary and lateral roots through alterations in auxin and ethylene, leading to new patterns of root architecture in rice seedlings. Selenium (Se) at low concentrations can control root growth through interaction with hormone biosynthesis. Auxin and ethylene have been shown to control the root architecture, with most of the information obtained from the eudicots such Arabidopsis and Nicotiana tabacum. Here, we presented the effects of Se on auxin and ethylene pathways and examined their impact on primary metabolism and root system architecture in rice (Oryza sativa L.) seedlings. Se treatment increased elongation of primary root, but decreased the number and length of lateral roots. Se led to decreased expression of genes associated with the biosynthesis of auxin and ethylene, concomitantly with reduced production of these hormones by the roots. Moreover, Se decreased the abundance of transcripts encoding auxin transport proteins. Indole-3-acetic acid (IAA) treatment overrode the repressive effect of Se on lateral root growth. The ethylene synthesis inhibitor L-α-(2-aminoethoxyvinyl)-glycine (AVG) increased elongation of primary root, whereas the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) resulted in the opposite effect. Soluble sugars accumulate in roots of rice seedlings under Se treatment. Thus, Se modulates the formation of primary and lateral roots through alterations in auxin and ethylene, leading to new patterns of root architecture in rice seedlings.


Assuntos
Ácidos Indolacéticos/farmacologia , Oryza/efeitos dos fármacos , Reguladores de Crescimento de Planta/metabolismo , Selênio/farmacologia , Transporte Biológico , Regulação para Baixo/efeitos dos fármacos , Etilenos/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Ácidos Indolacéticos/metabolismo , Oryza/anatomia & histologia , Oryza/metabolismo , Reguladores de Crescimento de Planta/farmacologia , Raízes de Plantas/anatomia & histologia , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Plântula/anatomia & histologia , Plântula/genética , Plântula/metabolismo
20.
Artigo em Inglês | MEDLINE | ID: mdl-30966870

RESUMO

A new adsorbent for removing copper ions from aqueous solutions has been developed and characterized. The present study deals with the sorption of Cu(II) from aqueous solution on chemically pretreated sodium carbonate-treated rice husk (SCRH). The physico-chemical characteristics of rice husks were investigated to analyze their suitability to adsorb Cu(II) ions from water and wastewater. The raw rice husk (RRH), SCRH and Cu(II) adsorbed rice husk were analyzed by SEM-EDAX analysis. FTIR spectroscopy was also applied to identify functional groups, capable of adsorbing metal ions. Batch kinetic studies were conducted for the adsorption of Cu(II) on SCRH. It has been observed that 92.9-96.0% removal of Cu(II) is achieved at 4.8 mg of Cu(II)/g of adsorbent, adsorbent dose of 10 g L-1 and initial Cu(II) concentration of 10 mg L-1 in a temperature range of 15-50 °C. It was observed that the adsorption of Cu(II) on SCRH followed pseudo second-order kinetic and time to achieve equilibrium was found to be 60 min. The maximum uptake (97%) of Cu (II) was observed at pH 6. In this paper, an attempt has also been made to develop simple and readily understandable thermodynamic parameters related to sorption process at the equilibrium for understanding the adsorption mechanism. The Gibbs free energy ΔG° values for the adsorption processes of Cu(II) at 15, 30, 40 and 50 °C were calculated as -6.16, -6.84, -8.01 and -8.53 kJ mol-1, respectively. The negative value of ΔG° indicates spontaneity of adsorption. The values of ΔH° and ΔS° for Cu(II) adsorption were calculated as 14.37 kJ mol-1 and 70.92 J K-1 mol-1, respectively. The activation energy for the adsorption of Cu(II) was found to be 9 kJ mol-1 which is a characteristic for diffusion limited processes.


Assuntos
Carbonatos/farmacologia , Cobre/isolamento & purificação , Oryza/efeitos dos fármacos , Oryza/metabolismo , Purificação da Água/métodos , Água/química , Adsorção , Biodegradação Ambiental , Biomassa , Carbonatos/química , Cobre/química , Cobre/farmacocinética , Difusão , Concentração de Íons de Hidrogênio , Cinética , Soluções , Termodinâmica , Poluentes Químicos da Água/isolamento & purificação , Poluentes Químicos da Água/farmacocinética
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