Cost-benefit analysis of nanofertilizers and nanopesticides emphasizes the need to improve the efficiency of nanoformulations for widescale adoption.

Nanotechnology-based approaches have demonstrated encouraging results for sustainable agriculture production, particularly in the field of fertilizers and pesticide innovation. It is essential to evaluate the economic and environmental benefits of these nanoformulations. Here we estimate the potential revenue gain/loss associated with nanofertilizer and/or nanopesticide use, calculate the greenhouse gas emissions change from the use of nanofertilizer and identify feasible applications and critical issues.

Changes in Metal-Chelating Metabolites Induced by Drought and a Root Microbiome in Wheat.

The essential metals Cu, Zn, and Fe are involved in many activities required for normal and stress responses in plants and their microbiomes. This paper focuses on how drought and microbial root colonization influence shoot and rhizosphere metabolites with metal-chelation properties. Wheat seedlings, with and without a pseudomonad microbiome, were grown with normal watering or under water-deficit conditions.

Absence of Nanoparticle-Induced Drought Tolerance in Nutrient Sufficient Wheat Seedlings.

Strategies to reduce crop losses due to drought are needed as climate variability affects agricultural productivity. Wheat ( var. Juniper) growth in a nutrient-sufficient, solid growth matrix containing varied doses of CuO, ZnO, and SiO nanoparticles (NPs) was used to evaluate NP mitigation of drought stress.

Illumina sequencing of 16S rRNA tag shows disparity in rhizobial and non-rhizobial diversity associated with root nodules of mung bean (Vigna radiata L.) growing in different habitats in Pakistan.

In Rhizobium-legume symbiosis, the nodule is the most frequently studied compartment, where the endophytic/symbiotic microbiota demands critical investigation for development of specific inocula. We identified the bacterial diversity within root nodules of mung bean from different growing areas of Pakistan using Illumina sequencing of 16S rRNA gene. We observed specific OTUs related to specific site where Bradyrhizobium was found to be the dominant genus comprising of 82-94% of total rhizobia in nodules with very minor fraction of sequences from other rhizobia at three sites.

Impact of soil salinity on the microbial structure of halophyte rhizosphere microbiome.

The rhizosphere microbiome plays a significant role in the life of plants in promoting plant survival under adverse conditions. However, limited information is available about microbial diversity in saline environments. In the current study, we compared the composition of the rhizosphere microbiomes of the halophytes Urochloa, Kochia, Salsola, and Atriplex living in moderate and high salinity environments (Khewra salt mines; Pakistan) with that of the non-halophyte Triticum.

Rhizosphere interactions between copper oxide nanoparticles and wheat root exudates in a sand matrix: Influences on copper bioavailability and uptake.

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.

Retrieved 16S rRNA and nifH sequences reveal co-dominance of Bradyrhizobium and Ensifer (Sinorhizobium) strains in field-collected root nodules of the promiscuous host Vigna radiata (L.) R. Wilczek.

In the present study, the relative distribution of endophytic rhizobia in field-collected root nodules of the promiscuous host mung bean was investigated by sequencing of 16S ribosomal RNA (rRNA) and nifH genes, amplified directly from the nodule DNA. Co-dominance of the genera Bradyrhizobium and Ensifer was indicated by 32.05 and 35.

Biofilms Benefiting Plants Exposed to ZnO and CuO Nanoparticles Studied with a Root-Mimetic Hollow Fiber Membrane.

Plants exist with a consortium of microbes that influence plant health, including responses to biotic and abiotic stress. While nanoparticle (NP)-plant interactions are increasingly studied, the effect of NPs on the plant microbiome is less researched. Here a root-mimetic hollow fiber membrane (HFM) is presented for generating biofilms of plant-associated microbes nurtured by artificial root exudates (AREs) to correlate exudate composition with biofilm formation and response to NPs.

CuO and ZnO Nanoparticles Modify Interkingdom Cell Signaling Processes Relevant to Crop Production.

As the world population increases, strategies for sustainable agriculture are needed to fulfill the global need for plants for food and other commercial products. Nanoparticle formulations are likely to be part of the developing strategies. CuO and ZnO nanoparticles (NPs) offer potential as fertilizers, as they provide bioavailable essential metals, and as pesticides, because of dose-dependent toxicity.

Dehalococcoides and general bacterial ecology of differentially trichloroethene dechlorinating flow-through columns.

The diversity of Dehalococcoides mccartyi (Dhc) and/or other organohalide respiring or associated microorganisms in parallel, partial, or complete trichloroethene (TCE) dehalogenating systems has not been well described. The composition of Dhc populations and the associated bacterial community that developed over 7.5 years in the top layer (0-10 cm) of eight TCE-fed columns were examined using pyrosequencing.

New Arsenate Reductase Gene (arrA) PCR Primers for Diversity Assessment and Quantification in Environmental Samples.

Unlabelled: The extent of arsenic contamination in drinking water and its potential threat to human health have resulted in considerable research interest in the microbial species responsible for arsenic reduction. The arsenate reductase gene (arrA), an important component of the microbial arsenate reduction system, has been widely used as a biomarker to study arsenate-reducing microorganisms. A new primer pair was designed and evaluated for quantitative PCR (qPCR) and high-throughput sequencing of the arrA gene, because currently available PCR primers are not suitable for these applications.

A Root-Colonizing Pseudomonad Lessens Stress Responses in Wheat Imposed by CuO Nanoparticles.

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.

Association of plant growth-promoting Serratia spp. with the root nodules of chickpea.

Serratia species-affiliated DNA sequences have recently been discovered in the root nodules of two chickpea cultivars; however, little is known about their potential influence on chickpea plant growth. All Serratia-affiliated sequences (1136) could be grouped into two clusters at 98% DNA similarity. The major cluster, represented by 96% of sequences, was closely associated with Serratia marcescens sequences from GenBank.

Ag nanoparticles generated using bio-reduction and -coating cause microbial killing without cell lysis.

Cost-effective "green" methods of producing Ag nanoparticles (NPs) are being examined because of the potential of these NPs as antimicrobials. Ag NPs were generated from Ag ions using extracellular metabolites from a soil-borne Pythium species. The NPs were variable in size, but had one dimension less than 50 nm and were biocoated; aggregation and coating changed with acetone precipitation.

Dehalococcoides abundance and alternate electron acceptor effects on large, flow-through trichloroethene dechlorinating columns.

Trichloroethene (TCE) in groundwater is a major health concern and biostimulation/bioaugmentation-based strategies have been evaluated to achieve complete reductive dechlorination with varying success. Different carbon sources were hypothesized to stimulate different extents of TCE reductive dechlorination. Ecological conditions that developed different dechlorination stages were investigated by quantitating Dehalococcoides 16S rRNA (Dhc) and reductive dehalogenase gene abundance, and by describing biogeochemical properties of laboratory columns in response to this biostimulation.

Bioaccumulation of copper, lead, and zinc in six macrophyte species grown in simulated stormwater bioretention systems.

Stormwater bioretention (BR) systems collect runoff containing heavy metals, which can concentrate in soil environments and potentially leach into groundwater. This greenhouse experiment evaluated differences among six plant species undergoing three varying hydraulic and pollutant loads in their bioaccumulation potential when subjected to continual application of low metal concentrations as a means of preventing copper, lead, and zinc accumulation in the BR soil. Results show that >92% of metal mass applied to the treatments via synthetic stormwater was removed from the exfiltrate within 27 cm of soil depth.

Pesticidal activity of metal oxide nanoparticles on plant pathogenic isolates of Pythium.

CuO and ZnO nanoparticles (NPs) have antimicrobial effects that could lead to formulations as pesticides for agriculture or medicine. The responses of two soil-borne plant pathogenic Pythium isolates to the NPs were studied to determine the potential of these metal oxide NPs as pesticides. Growth of the P.

Salts affect the interaction of ZnO or CuO nanoparticles with wheat.

Exposure to nanoparticles (NPs) that release metals with potential phytotoxicity could pose problems in agriculture. The authors of the present study used growth in a model growth matrix, sand, to examine the influence of 5 mmol/kg of Na, K, or Ca (added as Cl salts) and root exudates on transformation and changes to the bioactivity of copper(II) oxide (CuO) and zinc oxide (ZnO) NPs on wheat. These salt levels are found in saline agricultural soils.

The phytotoxicity of ZnO nanoparticles on wheat varies with soil properties.

Zn is an essential element for plants yet some soils are Zn-deficient and/or have low Zn-bioavailability. This paper addresses the feasibility of using ZnO nanoparticles (NPs) as soil amendments to improve Zn levels in the plant. The effects of soil properties on phytotoxicity and Zn bioavailability from the NPs were studied by using an acidic and a calcareous alkaline soil.

Nano-CuO and interaction with nano-ZnO or soil bacterium provide evidence for the interference of nanoparticles in metal nutrition of plants.

The expansion of nanotechnology raises concerns about the consequences of nanomaterials in plants. Here, the effects of nanoparticles (NPs; 100-500 mg/kg) on processes related to micronutrient accumulation were evaluated in bean (Phaseolus vulgaris) exposed to CuO NPs, a mixture of CuO and ZnO (CuO:ZnO) NPs, and in CuO NP-exposed plants colonized by a root bacterium, Pseudomonas chlororaphis O6 (PcO6) in a sand matrix for 7 days. Depending on exposure levels, the inhibition of growth by CuO NPs was more apparent in roots (10-66 %) than shoots (9-25 %).

ZnO nanoparticles and root colonization by a beneficial pseudomonad influence essential metal responses in bean (Phaseolus vulgaris).

Nanoparticles (NPs) incorporated into commercial products are reactive on plants. Here, the influence of a root-associated bacterium, Pseudomonas chlororaphis O6 (PcO6) on the responses of bean (Phaseolus vulgaris) to commercial ZnO nanoparticles (NPs) was examined. ZnO NPs (250-1000 mg Zn/kg) significantly (p = 0.

Arsenic(V) reduction in relation to Iron(III) transformation and molecular characterization of the structural and functional microbial community in sediments of a basin-fill aquifer in Northern Utah.

Basin-fill aquifers of the Southwestern United States are associated with elevated concentrations of arsenic (As) in groundwater. Many private domestic wells in the Cache Valley Basin, UT, have As concentrations in excess of the U.S.

Components from wheat roots modify the bioactivity of ZnO and CuO nanoparticles in a soil bacterium.

ZnO and CuO nanoparticles (NPs) have widespread commercial uses and their impact on agricultural systems is unresolved. This study examined whether the metabolites washed from wheat (Triticum aestivum L.) roots modulated the metabolic response to the NPs of a biosensor generated in the root colonizer, Pseudomonas putida KT2440.

Antifungal activity of ZnO nanoparticles and their interactive effect with a biocontrol bacterium on growth antagonism of the plant pathogen Fusarium graminearum.

Fungal plant pathogens such as Fusarium graminearum cause severe global economic losses in cereals crops, and current control measures are limited. This work addresses the potential for ZnO nanoparticles (NPs) and biocontrol bacteria to be used in plant fungal control strategies. Growth of F.

Fate of CuO and ZnO nano- and microparticles in the plant environment.

The environmental fate of metal oxide particles as a function of size was assessed by comparing the behavior of CuO or ZnO nanoparticles (NPs) to that of the corresponding microparticles (MPs) in a sand matrix, with and without wheat (Triticum aestivum L.) growth. After 14 days of incubation in the planted sand, the CuO and ZnO NPs were increased from their nominal sizes of <50 nm and <100 nm, to ~317 nm and ~483 nm, respectively.