Green Synthesis of Different Nanoparticles and its Effect on Irrigation Water and Soil Properties and Origanum Majorana Productivity

The term of nanotechnology has emerged recently in several fields of interest that refers to the researches and innovations that are concerned with making materials on a very small size close to the scale of atoms and molecules. In the present work, the effects of green synthesis of different nanoparticles on the quality of irrigation water, the availability of some heavy metals content in soil and the plant, and the productivity of Marjoram were studied in detail. The obtained results showed that the addition of nanoparticles (NPs) materials has resulted in noticeable variations in the removal percentages of Cu and Fe from aqueous solution. The maximum values obtained for adsorption of Cu (II) on ZnO, MgO, and SiO2 NPs, within pH (3–5) were 89.9%, 83.3%, and 68.36%, respectively. Whereas, the maximum adsorption values of Fe (III) at pH 3.3 were 82%, 80%, and 65% for ZnO, MgO, and SiO2 NPs, respectively. It was clearly seen that the effective of NPs application on reduction of the available Cu in the studied soil samples. The order of sequence for the effects of NPs application was found to take the following order Zn2 > Zn1 > Mg2 > Si2 > Mg 1 > Si1 > C (control). The highest values of the available Cu were observed in the control treatment, whereas the lowest values were obtained when Zn2 was added, and the same tendency was observed with the substantial concentrations of Fe. The addition of NPs to the soil samples had positively affected the Cu uptake via plant. The effects of NPs and the additions of Cu and Fe on the availability of NPK in the soil system were very completed and osculated from one treatment to another. The same tendency was observed with the total concentration of NPK in the plant.

Stable Cu Isotope Ratios Show Changes in Cu Uptake and Transport Mechanisms in Vitis vinifera Due to High Cu Exposure

Even though copper (Cu) is an essential plant nutrient, it can become toxic under certain conditions. Toxic effects do not only depend on soil Cu content, but also on environmental and physiological factors, that are not well understood. In this study, the mechanisms of Cu bioavailability and the homeostasis of Vitis vinifera L. cv. Tannat were investigated under controlled conditions, using stable Cu isotope analysis. We measured Cu concentrations and δ65Cu isotope ratios in soils, soil solutions, roots, and leaves of grapevine plants grown on six different vineyard soils, in a 16-week greenhouse experiment. The mobility of Cu in the soil solutions was controlled by the solubility of soil organic matter. No direct relationship between Cu contents in soils or soil solutions and Cu contents in roots could be established, indicating a partly homeostatic control of Cu uptake. Isotope fractionation between soil solutions and roots shifted from light to heavy with increasing Cu exposure, in line with a shift from active to passive uptake. Passive uptake appears to exceed active uptake for soil solution concentrations higher than 270 μg L–1. Isotope fractionation between roots and leaves was increasingly negative with increasing root Cu contents, even though the leaf Cu contents did not differ significantly. Our results suggest that Cu isotope analysis is a sensitive tool to monitor differences in Cu uptake and translocation pathways even before differences in tissue contents can be observed.

Impact of Foliar Application of Nano Nitrogen, Zinc and Copper on Yield and Nutrient Uptake of Rice

A field experiment was conducted during spring 2020-21 at Wetland farms of Tamil Nadu Agricultural University, Coimbatore to study the effect of foliar Nanonutrients (N, Zn and Cu) application on the yield and nutrient uptake by rice at harvest. Twelve treatments with three replications were laid out in randomized complete block design. The results revealed that application of 100% NPK + Nano N at active tillering (T3) and 75% N + 100% PK + Nano N at active tillering (T4) increased the grain yield (5112 and 5063 kg ha-1) and N uptake (106.48 and 89.51 kg ha-1) of rice, respectively and was on par with 100% NPK + Nano Zn at active tillering and panicle emergence (T10). However, significantly higher Zn and Cu uptake were recorded in 100% NPK + Nano Zn at active tillering and panicle emergence (T10, 457.61 g ha-1) and 100% NPK + Nano Cu at active tillering and panicle emergence (T12, 92.36 g ha-1), respectively which was followed by 100% NPK + Nano N at active tillering (T3, 372.45 and 81.51 g ha-1) and 75% N + 100% PK + Nano N at active tillering (T4, 355.41 and 84.13 g ha-1). Thus, it can be concluded that application of foliar Nano N at active tillering along with soil application of either 100% NPK or 75% N + 100% PK can provide better results in terms of grain yield and nutrient uptake.

Effect of Chloride Concentration on the Cytotoxicity, Bioavailability, and Bio-Reactivity of Copper and Silver in the Rainbow Trout Gut Cell Line (RTgutGC)

Chloride (Cl-) influences the bioavailability and toxicity of metals in fish, but the mechanisms by which it influences these processes is poorly understood. Here, we investigated the effect of chloride on the cytotoxicity, bioavailability (i.e., accumulation) and bio-reactivity (i.e., induction of mRNA levels of metal responsive genes) of copper (Cu) and silver (Ag) in the rainbow trout gut cell line (RTgutGC). Cells were exposed to metals in media with varying Cl- concentrations (0, 1, 5 and 146 mM). Metal speciation in exposure medium was analyzed using Visual MINTEQ software. Cytotoxicity of AgNO3 and CuSO4 was measured based on two endpoints: metabolic activity and membrane integrity. Cells were exposed to 500 nM of AgNO3 and CuSO4 for 24 hours in respective media to determine metal bioavailability and bioreactivity. Ag speciation changes from free ionic (Ag+) to neutral (AgCl), to negatively charged chloride complexes (AgCl2-, AgCl3-) with increasing Cl- concentration in exposure media whereas Cu speciation remains in two forms (Cu2+ and CuHPO4) across all media. Chloride does not affect Ag bioavailability but decreases metal toxicity and bio-reactivity. Cells exposed to Ag expressed significantly higher metallothionein mRNA levels in low Cl- media (0, 1, and 5 mM) than in high Cl- medium (146 mM). This suggests that chloride complexation reduces silver bio-reactivity and toxicity. Conversely, Cu bioavailability and toxicity were higher in the high chloride medium (146 mM) than in the low Cl- (0, 1, and 5 mM) media, supporting the hypothesis that Cu uptake may occur via a chloride dependent mechanism.

Adaptive Responses of Citrus grandis Leaves to Copper Toxicity Revealed by RNA-Seq and Physiology

Copper (Cu)-toxic effects on Citrus grandis growth and Cu uptake, as well as gene expression and physiological parameters in leaves were investigated. Using RNA-Seq, 715 upregulated and 573 downregulated genes were identified in leaves of C. grandis seedlings exposed to Cu-toxicity (LCGSEC). Cu-toxicity altered the expression of 52 genes related to cell wall metabolism, thus impairing cell wall metabolism and lowering leaf growth. Cu-toxicity downregulated the expression of photosynthetic electron transport-related genes, thus reducing CO2 assimilation. Some genes involved in thermal energy dissipation, photorespiration, reactive oxygen species scavenging and cell redox homeostasis and some antioxidants (reduced glutathione, phytochelatins, metallothioneins, l-tryptophan and total phenolics) were upregulated in LCGSEC, but they could not protect LCGSEC from oxidative damage. Several adaptive responses might occur in LCGSEC. LCGSEC displayed both enhanced capacities to maintain homeostasis of Cu via reducing Cu uptake by leaves and preventing release of vacuolar Cu into the cytoplasm, and to improve internal detoxification of Cu by accumulating Cu chelators (lignin, reduced glutathione, phytochelatins, metallothioneins, l-tryptophan and total phenolics). The capacities to maintain both energy homeostasis and Ca homeostasis might be upregulated in LCGSEC. Cu-toxicity increased abscisates (auxins) level, thus stimulating stomatal closure and lowering water loss (enhancing water use efficiency and photosynthesis).

Effect of Integrated Potassium Application on Growth, Yield and Micronutrient Uptake by Forage Maize (Zea mays L.)

A pot experiment was conducted during kharif season of 2019 to carry out the study on “Interactive effect of potash (K2O), potassium mobilizing bacteria (KMB) and FYM on forage yield, nutrient uptake by forage maize and soil fertility in a loamy sand soil of middle Gujarat”. Application of K2O @ 60 kg ha-1, KMB and FYM recorded significantly the highest plant height of forage maize at harvest over respective control. Crop fertilized with K2O @ 60 kg ha-1 and KMB gave significantly the highest green forage and dry matter yield. The results indicated that application of K2O @ 60 kg ha-1, potassium mobilizing bacteria recorded significantly the highest uptake of N, P, K, Fe and Zn by crop at harvest. Significantly the highest uptake of N, K and Cu were found with application of FYM @10 t ha-1. Significantly the highest K uptake by maize as well as higher P and Zn uptake by maize were observed due to interaction effect of K × KMB (60 kg K2O ha-1 with KMB). In case of N and Cu uptake by maize were noted the Significantly higher due to interaction effect of K × KMB (30 kg K2O ha-1 with KMB) and K × KMB × FYM (60 kg K2O ha-1 with KMB and FYM), respectively. The integrated use of potassium fertilizers along with KBM or in combination with FYM significantly improved the maize grain and nutrient uptake.

Cysteine Mutants of the Major Facilitator Superfamily-Type Transporter CcoA Provide insight into Copper Import

CcoA belongs to the widely distributed bacterial copper (Cu) importer subfamily CalT (CcoA-like Transporters) of the Major Facilitator Superfamily (MFS), and provides cytoplasmic Cu needed for cbb3-type cytochrome c oxidase (cbb3-Cox) biogenesis. Earlier studies have supported a 12 transmembrane helices (TMH) topology of CcoA with the well-conserved Met233xxxMet237 and His261xxxMet265 motifs in its TMH7 and TMH8, respectively. Of these residues, Met233 and His261 are essential for Cu uptake and cbb3-Cox production, whereas Met237 and Met265 contribute partly to these processes. CcoA also contains five Cys residues of unknown role, and remarkably, its structural models predict that three of these are exposed to the highly oxidizing periplasm. Here, we first demonstrate that elimination of both Met237 and Met265 completely abolishes Cu uptake and cbb3-Cox production, indicating that CcoA requires at least one of these two Met residues for activity. Second, using scanning mutagenesis to probe plausible metal-interacting Met, His and Cys residues of CcoA we found that the periplasm-exposed Cys49 located at the end of TMH2, the Cys247 on a surface loop between TMH7 and THM8, and the C367 located at the end of TMH11 are important for CcoA function. Analyses of the single and double Cys mutants revealed the occurrence of a disulfide bond in CcoA in vivo, possibly related to conformational changes it undergoes during Cu import as MFS-type transporter. Our overall findings suggested a model linking Cu import for cbb3-Cox biogenesis with a thiol: disulfide oxidoreduction step, advancing our understanding of the mechanisms of CcoA function.

EFFECT OF DIFFERENT BORON SOURCES AND LEVELS ON MACRO AND MICRONUTRIENT UPTAKE AND POST-HARVEST AVAILABILITY IN SALINE SODIC SOIL

The study was conducted to assess the effect of different boron sources and levels of macro and micronutrient uptake andpostharvest availability in saline sodic soil. Four levels of B (0, 0.5, 1.0 and 1.5 mg kg-1) was supplied through three different sources, namely borax, sodium octaborate and magnesium boro humate complex. A total of twelve treatment combinations were laidin factorial CRD design with three replications. Cotton var. LRA5166 was chosen as the test crop. The results revealed that application of 1.5 mg B kg-1 as magnesium boro humaterecorded the highest NPK uptake of 3.05, 0.99 and 2.55 g pot-1, respectively and the highest mean Zn, Fe, Mn and Cu uptake of 8.78, 13.69, 5.93 and 1.84 mg pot-1, respectively.The available NPK and other micronutrient status in post-harvest soil were invariably not influenced by the source and levels of the boron sources.

Ferrous Ions Inhibit Cu Uptake and Accumulation via Inducing Iron Plaque and Regulating Metabolism of Rice Plants Exposed to CuO Nanoparticles

Ferrous ions (Fe2+) in the rhizosphere play an indispensable role in the interaction between plants and nanoparticles (NPs). Here, we investigated the effect of Fe2+ (3 mM) on the dynamic...

Root System Architecture, Copper Uptake and Tissue Distribution in Soybean (Glycine max (L.) Merr.) Grown in Copper Oxide Nanoparticle (CuONP)-Amended Soil and Implications for Human Nutrition

Understanding the potential uptake and biodistribution of engineered nanoparticles (ENPs) in soil-grown plants is imperative for realistic toxicity and risk assessment considering the oral intake of edibles by humans. Herein, growing N-fixing symbiont (Bradyrhizobium japonicum) inoculated soybean (Glycine max (L.) Merr.) for a full lifecycle of 120 days, we assessed the potential influence of particle size (25, 50, and 250 nm) and concentration (0, 50, 100, 200, and 500 mg/kg soil) of Copper oxide nanoparticles (CuONPs) on: (1) root system architecture, (2) soil physicochemical attributes at the soil–root interface, and (3) Cu transport and accumulation in root, stem, leaf, and seed in soybean, and compared them with the soluble Cu2+ ions and water-only controls. Finally, we performed a comparative assessment of total seed Cu levels in soybean with other valuable food sources for Cu intake and discussed potential human health implications. Results showed particle size- and concentration-dependent influence of CuONPs on Cu uptake and distribution in root, stem, leaf, and seed. Alterations in root architecture (root biomass, length, volume, and area) were dependent on the Cu compound types, Cu concentrations, and their interactions. Concentration–response relationships for all three sizes of CuONPs and Cu2+ ions were found to be linear. Furthermore, CuONPs and Cu2+ ions had inhibitory effects on root growth and development. Overall, soybean responses to the smallest size of CuONPs–25 nm—were greater for all parameters tested compared to the two larger-sized CuONPs (50 nm, 250 nm) or Cu2+ ions. Results suggest that minor changes in soil-root physicochemical attributes may not be a major driver for Cu uptake in soybean. Cu bioaccumulation followed the order: root > leaf > stem > seed. Despite reduction in root architecture and seed yield, the smallest size CuONPs–25 nm led to increased total seed Cu uptake compared to the larger-sized CuONPs or Cu2+ ions. Our findings also suggest that soil amendment with CuONPs, and more so with the smallest size of CuONPs–25 nm—could significantly improve seed nutritional Cu value in soybean as reflected by the % Daily Values (DV) and are rated “Good” to “Very Good” according to the “World’s Healthiest Foods” rating. However, until the potential toxicity and risk from CuONP-fortified soybean seed ingestion is characterized in humans, we caution recommending such seeds for daily human consumption when addressing food Cu-deficiency and associated diseases, globally.