Cu from dissolution of CuO nanoparticles signals changes in root morphology (original) (raw)
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A Root-Colonizing Pseudomonad Lessens Stress Responses in Wheat Imposed by CuO Nanoparticles
PloS one, 2016
Nanoparticle (NPs) containing essential metals are being considered in formulations of fertilizers to boost plant nutrition in soils with low metal bioavailability. This paper addresses whether colonization of wheat roots by the bacterium, Pseudomonas chlororaphis O6 (PcO6), protected roots from the reduced elongation caused by CuO NPs. There was a trend for slightly elongated roots when seedlings with roots colonized by PcO6 were grown with CuO NPs; the density of bacterial cells on the root surface was not altered by the NPs. Accumulations of reactive oxygen species in the plant root cells caused by CuO NPs were little affected by root colonization. However, bacterial colonization did reduce the extent of expression of an array of genes associated with plant responses to stress induced by root exposure to CuO NPs. PcO6 colonization also reduced the levels of two important chelators of Cu ions, citric and malic acids, in the rhizosphere solution; presumably because these acids were...
Sustainability
Wet chemistry was used to produce copper oxide nanoparticles (CuO NPs). The results indicated that most nanoparticles were bacillus-shaped and relatively uniform in size (less than 30 nm). The effect of synthesized CuO NPs on wheat (Triticum aestivum L.) germination and growth parameters was studied and compared to bulk Cu. The results showed that no significant difference was obtained in germination rate among all treatments. Bulk Cu additions significantly affect the mean germination rate and mean germination time. On the contrary, germinability was significantly affected by CuO NPs additions. Seed vigor index was calculated to demonstrate the superior treatment in wheat germination parameters, and the results confirmed that 0.1 mg L−1 of CuO NPs could be successfully used to improve wheat seed germination. Moreover, the general average Cu concentrations in the plant tissue were 139 and 103 mg kg−1 dry weight for bulk and CuO NPs, respectively, indicating the dissolution behavior ...
Ecotoxicology, 2014
10 Abstract The expansion of nanotechnology raises con-11 cerns about the consequences of nanomaterials in plants. 12 Here, the effects of nanoparticles (NPs; 100-500 mg/kg) 13 on processes related to micronutrient accumulation were 14 evaluated in bean (Phaseolus vulgaris) exposed to CuO 15 NPs, a mixture of CuO and ZnO (CuO:ZnO) NPs, and in 16 CuO NP-exposed plants colonized by a root bacterium, 17 Pseudomonas chlororaphis O6 (PcO6) in a sand matrix for 18 7 days. Depending on exposure levels, the inhibition of 19 growth by CuO NPs was more apparent in roots (10-66 %) 20 than shoots (9-25 %) by CuO NPs. In contrast, CuO:ZnO 21 NPs or root colonization with PcO6 partially mitigated 22 growth inhibition. At 500 mg/kg exposure, CuO NPs 23 increased soluble Cu in the growth matrix by 23-fold, 24 relative to the control, while CuO:ZnO NPs increased 25 soluble Cu (26-fold), Zn (127-fold) and Ca (4.5-fold), but 26 reduced levels of Fe (0.8-fold) and Mn (0.75-fold). Shoot 27 accumulations of Cu (3.8-fold) and Na (1-fold) increased, 28 while those of Fe (0.4-fold), Mn (0.2-fold), Zn (0.5-fold) 29 and Ca (0.5-fold) were reduced with CuO NP (500 mg/kg) 30 exposure. CuO:ZnO NPs also increased shoot Cu, Zn and 31 Na levels, while decreasing that of Fe, Mn, Ca and Mg. 32 Root colonization reduced shoot uptake of Cu and Na, 15 33 and 24 %, respectively. CuO NPs inhibited ferric reductase 34 (up to 49 %) but stimulated cupric (up to 273 %) reductase 35 activity; while CuO:ZnO NPs or root colonization by PcO6 36 altered levels of ferric, but not copper reductase activity, 37 relative to CuO NPs. Cu ions at the level released from the 38 NPs did not duplicate these effects. Our findings demon-39 strate that in addition to the apparent toxic effects of NPs, 40 NP exposure may also have subtle impacts on secondary 41 processes such as metal nutrition. 42 43 Keywords Metal oxide nanoparticles Á Plant nutrition Á 44 Soil bacteria Á Solubility Á Bioaccumulation Á Reductase 45 A1 Electronic supplementary material The online version of this A2 article (
Environmental toxicology and chemistry, 2018
The impact of copper oxide nanoparticles (CuONPs) on crop production is dependent on the biogeochemistry of Cu in the rooting zone of the plant. The present study addressed the metabolites in wheat root exudates that increased dissolution of CuONPs and whether solubility correlated with Cu uptake into the plant. Bread wheat (Triticum aestivum cv. Dolores) was grown for 10 d with 0 to 300 mg Cu/kg as CuONPs in sand, a matrix deficient in Fe, Zn, Mn, and Cu for optimum plant growth. Increased NP doses enhanced root exudation, including the Cu-complexing phytosiderophore, 2'-deoxymugineic acid (DMA), and corresponded to greater dissolution of the CuONPs. Toxicity, observed as reduced root elongation, was attributable to a combination of CuONPs and dissolved Cu complexes. Geochemical modeling predicted that the majority of the solution phase Cu was complexed with citrate at low dosing or DMA at higher dosing. Altered biogeochemistry within the rhizosphere correlated with bio-respons...
Copper oxide nanoparticle effects on root growth and hydraulic conductivity of two vegetable crops
Plant and Soil, 2018
Aims Root growth and water transport were evaluated for two vegetable crops of contrasting root architecture (lettuce, carrot) exposed to copper oxide nanoparticles (CuO NPs). Methods 10-day seedling root growth assays were evaluated for 16 nanometer (nm) diameter CuO NP and CuCl 2 control (0.8-798.9 mg Cu L-1). In a separate experiment, hydraulic conductivity (K h) of root systems not previously exposed to NP was tested using 16 and 45 nm CuO NP (798.9 mg Cu L-1) relative to CuO NPfree controls, and xylem sap was assessed by TEM-EDS for presence of CuO NPs.
Botany
Formulations that include nanoparticles of CuO and ZnO are being considered for agricultural applications as fertilizers because they act as sources of Cu or Zn. Currently, few studies of the effects of these nanoparticles (NPs) consider the three-way interactions of NPs with the plant plus its microbiome. At doses that produced root shortening by both nanoparticles (NPs), CuO NPs induced the proliferation of elongated root hairs close to the root tip, and ZnO NPs increased lateral root formation in wheat seedlings (Triticum aestivum L.). These responses occurred with roots colonized by a beneficial bacterium, Pseudomonas chlororaphis O6 (PcO6), originally isolated from roots of wheat grown under dryland farming in calcareous soils. The PcO6-induced tolerance to drought stress in wheat seedlings was not impaired by the NPs. Rather, growth of the PcO6-colonized plants with NPs resulted in systemic increases in the expression of genes associated with tolerance to water stress. Increas...
Fate of CuO and ZnO Nano- and Microparticles in the Plant Environment
Environmental Science & Technology, 2013
Hydroponic plant growth studies indicate that silver nanoparticles (Ag NPs) are phytotoxic. In this work, the phytotoxicity of commercial Ag NPs (10 nm) was evaluated in a sand growth matrix. Both NPs and soluble Ag were recovered from water extracts of the sand after growth of plants challenged with the commercial product; the surface charge of the Ag NPs in this extract was slightly reduced compared to the stock NPs. The Ag NPs reduced the length of shoots and roots of wheat in a dose-dependent manner. Furthermore, 2.5 mg/kg of the NPs increased branching in the roots of wheat (Triticum aestivum L.), thereby affecting plant biomass. Micron-sized (bulk) Ag particles (2.5 mg/kg) as well as Ag ions (63 μg Ag/kg) equivalent to the amount of soluble Ag in planted sand with Ag NPs (2.5 mg/kg) did not affect plant growth compared to control. In contrast, higher levels of Ag ions (2.5 mg/kg) reduced plant growth to a similar extent as the Ag NPs. Accumulation of Ag was detected in the shoots, indicating an uptake and transport of the metal from the Ag NPs in the sand. Transmision electron microscopy indicated that Ag NPs were present in shoots of plants with roots exposed to the Ag NPs or high levels of Ag ions. Both of these treatments caused oxidative stress in roots, as indicated by accumulation of oxidized glutathione, and induced expression of a gene encoding a metallothionein involved in detoxification by metal ion sequestration. Our findings demonstrate the potential effects of environmental contamination by Ag NPs on the metabolism and growth of food crops in a solid matrix.
• Interactions of IAA × Cu compounds significantly reduced number of plants. • With two exceptions, IAA × Cu compounds did not significantly reduce pod biomass. • Exogenous IAA did not affect the accumulation of essential elements in pods. The response of plants to copper oxide nanoparticles (nano-CuO) in presence of exogenous phytohormones is unknown. In this study, green pea (Pisum sativum) plants were cultivated to full maturity in soil amended with nano-CuO (10–100 nm, 74.3% Cu), bulk-CuO (bCuO, 100–10,000 nm, 79.7% Cu), and CuCl 2 at 50 and 100 mg/kg and indole-3-acetic acid (IAA) at 10 and 100 μM. Results showed that IAA at 10 and 100 μM, averaged over all Cu treatments, reduced the number of plants by ~23% and ~34%, respectively. IAA at 10 μM, nano-CuO at 50 mg/kg, b-CuO at 50 mg/kg, and CuCl 2 at 100 mg/kg reduced pod biomass by about 50%. Although some combinations of IAA, mainly at 100 μM, with the Cu compounds altered nutrient accumulation in tissues, none of them affected pod elements. Conversely, without IAA, nano-CuO at 50 mg/kg, increased pod Fe and Ni by 258% and 325%, respectively, while bCuO at 100 mg/kg increased pod Ni by 275%, compared with control. With IAA at 10 μM, nano-CuO (100 mg/kg) and bCuO (50 mg/kg) increased stem Cu by ~84% and ~ 78%. When IAA increased to 100 μM, nano-CuO and bCuO reduced stem Ca by 32% and 37%, and Mg by ~ 35%. Results suggest that both the nano-CuO and bCuO could improve the nutritional quality of pea pods, while exogenous IAA combined with Cu-based compounds could impact green pea production since these treatments reduced the number of plants and pod biomass.
Environmental Pollution, 2018
Bulk Cu compounds such as Cu(OH) 2 are extensively used as pesticides in agriculture. Recent investigations suggest that Cu-based nanomaterials can replace bulk materials reducing the environmental impacts of Cu. In this study, stress responses of alfalfa (Medicago sativa L.) seedlings to Cu(OH) 2 nanoparticle or compounds were evaluated. Seeds were immersed in suspension/solutions of a Cu(OH) 2 nanoform, bulk Cu(OH) 2 , CuSO 4 , and Cu(NO 3) 2 at 25 and 75 mg/L. Six days later, the germination, seedling growth, and the physiological and biochemical responses of sprouts were evaluated. All Cu treatments significantly reduced root elongation (average ¼ 63%). The ionic compounds at 25 and 75 mg/ L caused a reduction in all elements analyzed (Ca, K, Mg, P, Zn, and Mn), excepting for S, Fe and Mo. The bulk-Cu(OH) 2 treatment reduced K (48%) and P (52%) at 75 mg/L, but increased Zn at 25 (18%) and 75 (21%) mg/L. The nano-Cu(OH) 2 reduced K (46%) and P (48%) at 75 mg/L, and also P (37%) at 25 mg/L, compared with control. Confocal microscopy images showed that all Cu compounds, at 75 mg/L, significantly reduced nitric oxide, concurring with the reduction in root growth. Nano Cu(OH) 2 at 25 mg/ L upregulated the expression of the Cu/Zn superoxide dismutase gene (1.92-fold), while ionic treatments at 75 mg/L upregulated (~10-fold) metallothionein (MT) transcripts. Results demonstrated that nano and bulk Cu(OH) 2 compounds caused less physiological impairments in comparison to the ionic ones in alfalfa seedlings.