Assessment of the oxidative stress intensity and the integrity of cell membranes under the manganese nanoparticles toxicity in wheat seedlings.

A response to manganese nanoparticles was studied in seedlings of two wheat cultivars and a model system of plant cell membranes. Nanoparticles at concentrations of 125 and 250 mg/ml were applied foliar. The application of NPs enhanced the content of Mn in plant cells, indicating its penetration through the leaf surface. The stressful effect in the plant cells was estimated based on changes in the activity of antioxidant enzymes, content of chlorophylls and starch. MnNPs evoked no significant changes in the leaf morphology, however, an increase in enzyme activity, starch accumulation, and a decrease in chlorophyll synthesis indicated the stress occurrence. Moreover, a rise in the electrokinetic potential of the chloroplast membrane surface and the reconstruction of their hydrophobic parts toward an increase in fatty acid saturation was found.

New Prospects for Improving Microspore Embryogenesis Induction in Highly Recalcitrant Winter Wheat Lines.

Among various methods stimulating biological progress, double haploid (DH) technology, which utilizes the process of microspore embryogenesis (ME), is potentially the most effective. However, the process depends on complex interactions between many genetic, physiological and environmental variables, and in many cases, e.g., winter wheat, does not operate with the efficiency required for commercial use. Stress associated with low-temperature treatment, isolation and transfer to in vitro culture has been shown to disturb redox homeostasis and generate relatively high levels of reactive oxygen species (ROS), affecting microspore vitality. The aim of this study was to investigate whether controlled plant growth, specific tiller pre-treatment and culture conditions could improve the potential of microspores to cope with stress and effectively induce ME. To understand the mechanism of the stress response, hydrogen peroxide levels, total activity and the content of the most important low-molecular-weight antioxidants (glutathione and ascorbate), as well as the content of selected macro- (Mg, Ca, NA, K) and micronutrients (Mn, Zn, Fe, Cu, Mo) were determined. These analyses, combined with the cytological characteristics of the microspore suspensions, allowed us to demonstrate that an increased microspore vitality and stronger response to ME induction were associated with higher stress resistance based on more efficient ROS scavenging and nutrient management. It was shown that a modified procedure, combining a low temperature with mannitol and sodium selenate tiller pre-treatment, reduced oxidative stress and improved the effectiveness of ME in winter wheat lines.

A Perspective of the Comprehensive and Objective Assessment of Analytical Methods Including the Greenness and Functionality Criteria: Application to the Determination of Zinc in Aqueous Samples.

The recently proposed concept of White Analytical Chemistry (WAC), referring to the Red-Green-Blue color model, combines ecological aspects (green) with functionality (red and blue criteria), presenting the complete method as "white". However, it is not easy to carry out an overall quantitative evaluation of the analytical method in line with the WAC idea in an objective manner. This paper outlines the perspective of the future development of such a possibility by attempting to answer selected questions about the evaluation process. Based on the study consisting in the evaluation of selected model methods by a group of 12 independent analysts, it was shown how well individual criteria are assessed, whether the variability of assessments by different people is comparable for each criterion, how large it is, and whether averaging the scores from different researchers can help to choose the best method more objectively.

Translocation of elements and sugars in wheat genotypes at vegetative and generative stages under continuous selenium exposure.

BACKGROUND: Biofortification with selenium (Se) elevates its concentration in feed and fodder plants and helps to prevent health problems in animals and humans. The aim of this study was to describe Se-induced modifications in the accumulation of elements important for the proper functioning of wheat, one of the most popular cereals. The presence of Se correlated with carbohydrate synthesis and electron paramagnetic resonance (EPR). This explained the mechanisms of Se's antioxidant activity. RESULTS: Selenium accumulation in vegetative and generative leaves, and in the grains of three wheat genotypes (cv. Parabola, cv. Raweta and cv. Manu), differing in their stress tolerance and grown hydroponically in the presence of 10 or 20 µM Na2 SeO4, , was proportional to its content in the medium. Stronger Se accumulation was typical of a stress-sensitive genotype. Selenium generally promoted the uptake of macronutrients and micronutrients but their distribution depended on tissue and genotype. Changes in the Se-induced EPR signals of paramagnetic metals and organic radicals corresponded with stress tolerance of the tested genotypes. CONCLUSIONS: Se application increased the accumulation of nutrients and carbohydrates that are vital for proper plant growth and development. Accelerated uptake of molybdenum (Mo), an element improving dietary properties of grains, may be an additional advantage of Se fertilization. The mechanisms of Se-induced changes in removing Mn and iron (Fe) ions from macromolecules may be one of the factors that differentiate plant tolerance to oxidative stress. © 2019 Society of Chemical Industry.

The role of chloroplasts in the oxidative stress that is induced by zearalenone in wheat plants - The functions of 24-epibrassinolide and selenium in the protective mechanisms.

This study focused on the idea that the toxic effect of zearalenone (ZEA) and the protective actions of the brassinosteroid - 24-epibrassinolide (EBR) as well as selenium are dependent on its accumulation in chloroplasts to a high degree. These organelles were isolated from the leaves of oxidative stress-sensitive and stress-tolerant wheat cultivars that had been grown from grains that had been incubated in a solution of ZEA (30 µM), Na2SeO4 (Se, 10 µM), EBR (0.1 µM) or in a mixture of ZEA with Se or EBR. Ultra-high performance liquid chromatography techniques indicated that ZEA was adsorbed in higher amounts in the chloroplasts in the sensitive rather than tolerant cultivar. Although the brassinosteroids and Se were also accumulated in the chloroplasts, higher levels were only found in the tolerant cultivar. The application of EBR increased the homocastasterone content, especially in the chloroplasts of the tolerant plant and after the addition of ZEA. The presence of both protectants caused a decrease in the ZEA content in studied organelles and resulted in diminishing of the oxidative stress (i.e. changes in the activity of the antioxidative enzymes). Moreover, a recovery of photosystem II and decrease in the negative impact of ZEN on Hsp90 transcript accumulation was observed in plants.

Flow manifold for chemical H-point standard addition method implemented to electrochemical analysis based on the capacitance measurements.

The paper presents a novel analytical method for electrochemical potassium determination using gold electrodes with self-assembled thiol monolayers (SATMs) deposited on its surface. The whole analytical procedure was carried out in a dedicated flow manifold using capacitance detection mode. The terminal functional groups on the surface of the dielectric monolayer interacts selectively with the analyte, changing the thickness of the layer depending on the amount of the analyte and the applied voltage, resulting in a change in the registered dielectric capacitance. New calibration approach based on the Chemical H-point Standard Addition Method (C-HPSAM), allowing both specific (proportional) and unspecific (constant) interference effects caused by sodium ions to be corrected, was applied. The calibration method is based on the registration of the calibration graphs by the standard addition method (SAM) three times in such different chemical conditions, which are able to differentiate the slope of each graph. The C-HPSAM was applied for the first time in electrochemical analysis. As a chemical parameter differentiating the sensitivity of the calibration graphs, the concentration of ionic strength stabilizer (ethylenediamine) was used. In order to improve the analytical procedure, to make it faster and automated, the dedicated flow system was applied. The constructed flow system was composed of several modules individually dedicated to the appropriate step of the whole analytical procedure: electrochemical cleaning of work electrode surface, adsorption of SATMs and analytical calibration. The calibration curves were obtained in the range of 0.1-0.9 mmol L-1 with good linearity (R2 = 0.996 ±â€¯0.001) and the LOD and LOQ of 28.6 and 85.8 µmol L-1, respectively. The proposed method was employed for potassium determination in highly mineralized water, juice and pharmaceutical samples without any special pretreatment.

An automated continuous homogeneous microextraction for the determination of selenium and arsenic by hydride generation atomic fluorescence spectrometry.

An automated continuous homogeneous microextraction approach based on a flow system has been developed and coupled with a hydride generation atomic fluorescence spectrometry system (HG-AFS). The developed approach was applied for the determination of trace arsenic and selenium in environmental water and liver samples. The nonanoic acid was investigated as a switchable hydrophilicity solvent (SHS) for homogeneous microextraction of As(III) and Se(IV) complexes with pyrrolidinedithiocarbamate (PDC). The procedure involved on-line mixing ammonium PDC (aqueous phase), sodium nonanoate (aqueous phase) and acid sample solution resulting in the formation of SHS (nonanoic acid) dispersed into the acid aqueous phase. By this continuous process, analytes complexes with PDC were formed and extracted into the fine SHS droplets followed by retention into a monolithic column packed with block of porous PTFE. Finally, the retained complexes were eluted with NaOH solution and delivered to the HG-AFS system. The limits of detection, calculated from a blank test based on 3σ, were 0.01µgL-1 for both analytes.