Accuracy of analytical standard solutions and the uncertainty in their nominal concentrations

In the last step of the analysis, the accuracy of analytical standard solutions has a decisive influence on the measurement results of pesticide residues, as well as all other chemical contaminants, and, in the case of actual concentrations differing from nominal ones, can result in a systematic error during the determination of sample components. Therefore, most of the laboratories who feel responsible for their results pay special attention to the preparation and storage of standard solutions, and to replenishing solvent losses due to possible evaporation, based on the mass measurements of vessels storing standard solutions before and after use. However, in our experience, much less attention than necessary is paid in practical work to monitoring the possible decomposition of individual active ingredients, and not appropriate statistical methods are used for the evaluation of the monitoring results. In our article, we present the standard preparation methods of two laboratories employing “good analytical practices”, analyze the uncertainties of the different steps, and make a recommendation for the preparation of the most accurate standard solutions

The effects of putrescine are partly overlapping with osmotic stress processes in wheat

Polyamine metabolism is in relation with several metabolic pathways and linked with plant hormones or signalling molecules; in addition polyamines may modulate the up- or down-regulation of gene expression. However the precise mechanism by which polyamines act at the transcription level is still unclear. In the present study the modifying effect of putrescine pre-treatment has been investigated using the microarray transcriptome profile analysis under the conditions where exogenous putrescine alleviated osmotic stress in wheat plants. Pre-treatment with putrescine induced the unique expression of various general stress-related genes. Although there were obvious differences between the effects of putrescine and polyethylene glycol treatments, there was also a remarkable overlap between the effects of putrescine and osmotic stress responses in wheat plants, suggesting that putrescine has already induced defence processes under control conditions. The fatty acid composition in certain lipid fractions and the antioxidant enzyme activities have also been specifically changed under osmotic stress conditions or after treatment with putrescine

Az analitikai standard oldatok pontossága és a névleges koncentrációjuk bizonytalansága

Az analitikai standard oldatok pontossága a növényvédő szermaradék, de minden más kémiai szennyező mérési eredményét a vizsgálat utolsó lépésében döntően befolyásolja, és a minta komponenseinek meghatározása során a névlegestől eltérő aktuális koncentráció tekintetében folyamatosan szisztematikus hibát eredményez. A legtöbb, eredményeiért felelősséget érző laboratórium ezért különös figyelmet fordít a standard oldatok elkészítésére és tárolására, illetve az oldószer esetleges elpárolgásából adódó veszteség pótlására a standard oldatokat tároló eszközök tömegének használat utáni és használat előtti mérése alapján. Tapasztalataink szerint azonban a gyakorlati munkában a szükségesnél sokkal kisebb figyelmet fordítanak az egyes hatóanyagok esetleges bomlásának ellenőrzésére, illetve nem a megfelelő statisztikai módszert alkalmazzák az ellenőrzési eredmények értékelésére. Cikkünkben bemutatjuk két, „jó analitikai gyakorlatot” alkalmazó laboratórium standard készítési módszereit, elemezzük az egyes lépések bizonytalanságát és javaslatot teszünk a legpontosabb standard oldatok elkészítési módjára

Activation of Local and Systemic Defence Responses by Flg22 Is Dependent on Daytime and Ethylene in Intact Tomato Plants

The first line of plant defence responses against pathogens can be induced by the bacterial flg22 and can be dependent on various external and internal factors. Here, we firstly studied the effects of daytime and ethylene (ET) using Never ripe (Nr) mutants in the local and systemic defence responses of intact tomato plants after flg22 treatments. Flg22 was applied in the afternoon and at night and rapid reactions were detected. The production of hydrogen peroxide and nitric oxide was induced by flg22 locally, while superoxide was induced systemically, in wild type plants in the light period, but all remained lower at night and in Nr leaves. Flg22 elevated, locally, the ET, jasmonic acid (JA) and salicylic acid (SA) levels in the light period; these levels did not change significantly at night. Expression of Pathogenesis-related 1 (PR1), Ethylene response factor 1 (ERF1) and Defensin (DEF) showed also daytime- and ET-dependent changes. Enhanced ERF1 and DEF expression and stomatal closure were also observable in systemic leaves of wild type plants in the light. These data demonstrate that early biotic signalling in flg22-treated leaves and distal ones is an ET-dependent process and it is also determined by the time of day and inhibited in the early night phase

Polyamine Metabolism under Different Light Regimes in Wheat

Although the relationship between polyamines and photosynthesis has been investigated at several levels, the main aim of this experiment was to test light-intensity-dependent influence of polyamine metabolism with or without exogenous polyamines. First, the effect of the duration of the daily illumination, then the effects of different light intensities (50, 250, and 500 μmol m(–2) s(–1)) on the polyamine metabolism at metabolite and gene expression levels were investigated. In the second experiment, polyamine treatments, namely putrescine, spermidine and spermine, were also applied. The different light quantities induced different changes in the polyamine metabolism. In the leaves, light distinctly induced the putrescine level and reduced the 1,3-diaminopropane content. Leaves and roots responded differently to the polyamine treatments. Polyamines improved photosynthesis under lower light conditions. Exogenous polyamine treatments influenced the polyamine metabolism differently under individual light regimes. The fine-tuning of the synthesis, back-conversion and terminal catabolism could be responsible for the observed different polyamine metabolism-modulating strategies, leading to successful adaptation to different light conditions

EGÉSZSÉGES ÉS FERTŐZÖTT MEZŐGAZDASÁGI NÖVÉNYEK, VALAMINT AGARICUS BISPORUS ILLATANYAGPROFILJÁNAK FELTÉRKÉPEZÉSE – ELŐTANULMÁNY

GINOP kutatócsoportunk, E-Orr kutatóműhely „Természetes szagmintázatok elemzése és agrártudományi hasznosítása” címmel 2017-óta működik Martonvásáron. Kutatásaink fő célja egy új típusú mesterséges érzékelő rendszer kifejlesztése, amellyel lehetőség nyílik mezőgazdasági növények komplex illatanyag-összetételének meghatározására. Eddig három növény (búza, árpa, paradicsom), valamint csiperkegomba illatanyagprofil elemzését végeztük el. Méréseink során igazoltuk, hogy különböző fertőzések hatására valóban megváltozik az adott növény illatanyag mintázata, azonban sok esetben csak kis mértékben

Toxicity and sublethal effects of chlorantraniliprole and indoxacarb on Spodoptera littoralis (Lepidoptera: Noctuidae)

Chlorantraniliprole and indoxacarb insecticides exhibit good efficiency for control lepidopteran pests. The current study is a comprehensive analysis of the effect of lethal and sublethal concentrations of these insecticides on Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) by using the leaf dipping technique. The LC50 values ranged from 0.06 to 1.07 mg/L, and 0.005 to 0.81 mg/L for chlorantraniliprole and indoxacarb, respectively. Our results showed that the treatment of the 2nd instar larvae with LC50 concentrations of these insecticides significantly increased the length of larval and pupal duration as well as pupal weight in most cases. While, no significant differences have been found in the percentage of hatchability except for LC50 equivalent of indoxacarb. Female behavior regarding calling activity decreased by 50–60% following exposure to the LC50 concentration of both insecticides. Gas chromatography analysis results showed that both insecticides lowered pheromone titer except at chlorantraniliprole LC50 equivalent for (Z,E)-9,12-tetradecadien-l-ol acetate, and indoxacarb LC10 equivalent for (Z)-9-tetradecenyl acetate. Additionally, the activity of mixed-function oxidases and glutathione S-transferase were elevated relative to control. The carboxylesterase activity significantly increased when assayed with both chlorant-raniliprole concentrations and indoxacarb LC10 equivalent. These results indicate that chlorantraniliprole and indoxacarb could be effective for S. littoralis control

Role of polyamines in plant growth regulation of Rht wheat mutants

Besides their protective role, polyamines also serve as signalling molecules. However, further studies are needed to elucidate the polyamine signalling pathways, especially to identify polyamine-regulated mechanisms and their connections with other regulatory molecules. Reduced height (Rht) genes in wheat are often used in breeding programs to increase harvest index. Some of these genes are encoding DELLA proteins playing role in gibberellic acid signalling. The aim of the present paper was to reveal how the mutations in Rht gene modify the polyamine-regulated processes in wheat. Wild type and two Rht mutant genotypes (Rht 1: semi-dwarf; Rht 3: dwarf mutants) were treated with polyamines. Polyamine treatments differently influenced the polyamine metabolism, the plant growth parameters and certain hormone levels (salicylic acid and abscisic acid) in these genotypes. The observed distinct metabolism of Rht 3 may more likely reflect more intensive polyamine exodus from putrescine to spermidine and spermine, and the catabolism of the higher polyamines. The lower root to shoot translocation of putrescine can contribute to the regulation of polyamine pool, which in turn may be responsible for the observed lack of growth inhibition in Rht 3 after spermidine and spermine treatments. Lower accumulation of salicylic acid and abscisic acid, plant hormones usually linked with growth inhibition, in leaves may also be responsible for the diminished negative effect of higher polyamines on the shoot growth parameters observed in Rht 3. These results provide an insight into the role of polyamines in plant growth regulation based on the investigation of gibberellin-insensitive Rht mutants