Polyethylene Glycol Concentration Research Articles

Extractive denitrogenization of liquid model fuel using polyethylene glycol methyl ether 350

AbstractIn the present study, we studied the effectiveness of the water‐soluble polymer polyethylene glycol methyl ether 350 (PEG ME‐350) on the extraction of nitrogen‐containing heterocyclic compounds—quinoline and indole—from n‐hexane. The dependences of the quantitative characteristics of the extraction of N‐compounds on the contact time of the phases, the content of PEG ME‐350 in the n‐hexane–water system, the initial concentration of nitrogen‐containing heterocyclic compounds in the organic phase, and the volumetric ratio of the phases were obtained. It has been established that PEG ME‐350 is an effective extractant in the process of stepwise extraction of quinoline and indole, and the mechanisms of their extraction have also been proposed and proven. The results can be further used in the purification of light hydrocarbon fractions from nitrogen‐containing heterocyclic compounds.

Facile Purification and Use of Tobamoviral Nanocarriers for Antibody-Mediated Display of a Two-Enzyme System.

Immunosorbent turnip vein clearing virus (TVCV) particles displaying the IgG-binding domains D and E of Staphylococcus aureus protein A (PA) on every coat protein (CP) subunit (TVCVPA) were purified from plants via optimized and new protocols. The latter used polyethylene glycol (PEG) raw precipitates, from which virions were selectively re-solubilized in reverse PEG concentration gradients. This procedure improved the integrity of both TVCVPA and the wild-type subgroup 3 tobamovirus. TVCVPA could be loaded with more than 500 IgGs per virion, which mediated the immunocapture of fluorescent dyes, GFP, and active enzymes. Bi-enzyme ensembles of cooperating glucose oxidase and horseradish peroxidase were tethered together on the TVCVPA carriers via a single antibody type, with one enzyme conjugated chemically to its Fc region, and the other one bound as a target, yielding synthetic multi-enzyme complexes. In microtiter plates, the TVCVPA-displayed sugar-sensing system possessed a considerably increased reusability upon repeated testing, compared to the IgG-bound enzyme pair in the absence of the virus. A high coverage of the viral adapters was also achieved on Ta2O5 sensor chip surfaces coated with a polyelectrolyte interlayer, as a prerequisite for durable TVCVPA-assisted electrochemical biosensing via modularly IgG-assembled sensor enzymes.

Aggregation behavior and dispersion stability of amphiphilic water-dispersed polyesters in aqueous solution

Amphiphilic polymer water-dispersed polyester (WPET) has important applications in the textile field. Due to the potential interactions among WPET molecules, the stability of their colloids is susceptible to external factors. This study focused on the effects of two hydrophilic groups (sulfonate group and PEG) on the aggregation behavior of WPET. In addition, the effects of concentration, temperature, and electrolytes on WPET aggregation behavior were systematically investigated. The more sulfonate group content in WPET, the higher stability with or without high electrolyte concentration it has. However, there is no clear correlation between the effect of PEG content and the dispersion stability of the WPET solution. The sulfonate group content in WPET is an important factor affecting its dispersion in aqueous solution. Meanwhile, WPET concentration, temperature, and electrolyte play important and complex roles in controlling the aggregation behaviors of the WPET. This fundamental research can be used to effectively control and improve the stability of WPET solutions and provide guidance for the prediction of dispersion and stability for molecules not yet synthesized.

A quasi-solid state polymer electrolyte for high-rate and long-life sodium-metal batteries

High-energy rechargeable sodium metal batteries, featuring quasi-solid polymer electrolytes (QSSPEs), hold the promise of improved safety. However, the low ionic conductivity and limited cyclability of QSSPEs at room temperature have paralyzed the efforts to develop energy-dense metal anode batteries. Herein, we report a QSSPE comprising a blend of polyvinyl pyrrolidone (PVP) and polyethylene glycol (PEG). Notably, the porosity and the electrolyte uptake capacity of the QSSPE are highly responsive to the concentration of PEG. The optimized PVP-based QSSPE (PVP-PEG 70 30) shows a high ionic conductivity of 1.06 mS cm−1 at room temperature, along with a high transference number of approximately 0.81. A sodium symmetric cell using PVP-PEG 70 30 demonstrates reversible stripping/plating of sodium for over 700 h at a current density of 1 mA cm−2. Furthermore, PVP-PEG 70 30 alters the localized chemistry of the solid electrolyte interphases (SEIs), facilitating the formation of fluorine-rich SEIs. When coupled with a Prussian blue cathode and sodium metal anode, a full cell employing PVP-PEG 70 30 exhibits an initial discharge capacity of 168 mAh g−1, with an average discharge capacity of 125 mAh g−1 for over 600 cycles at 0.5C. Remarkably, this cell can be cycled stably and reversibly at a high rate of 6.5C. These results suggest that PVP-based QSSPE holds great promise as an electrolyte candidate for high-performance sodium metal batteries.

Screening of Chickpea (Cicer arietinum L.) Genotypes against Drought Stress Employing Polyethylene Glycol 6000 as Selecting Agent

Chickpea (Cicer arietinum L.) stands as a prominent legume crop globally, renowned for its elevated protein content. The primary challenges to chickpea cultivation emanate from abiotic stressors, with drought reigning as the most pivotal contributor to diminished growth and production output. To select putative drought tolerant genotype (s), an in vitro screening method was deployed, utilizing different concentration of Polyethylene Glycol (PEG 6000) as selecting agent along with control. Seeds of twenty different genotypes were treated with different concentrations of PEG6000 and observations were recorded for shoot length (cm), root length (cm), germination percentage, relative water content, seedling vigour index and stress tolerance index (STI). Evidently, all assessed attributes exhibited a significant reduction commensurate with the augmentation of PEG6000. This trend detrimentally influenced germination and the entirety of seedling growth-related metrics. Furthermore, the distinction in variability across genotypes concerning germination percentage, vigour index, and stress tolerance index (STI) emerged as vigorous and informative standards for discriminating drought-tolerant chickpea genotype (s) during both germination and seedling phases. Investigative findings spotlighted the drought-tolerant disposition of genotypes, where genotypes viz., SAGL152252, ICC4958, and JG315 found to be putative drought tolerant based on different parameters investigated.

Modular Optical Diodes for Circular Polarization Based on Glass‐Supported Cellulose Nanocrystal/Polyethylene Glycol Composite Films

Depending on processing methods and conditions, cellulose nanocrystal (CNC) films exhibit linear birefringence or selective Bragg reflection. The latter means reflection of light with left‐handed circular polarization (LCP) due to CNC in a helicoidal microstructure of the same handedness. Herein, glass‐supported CNC/polyethylene glycol (CNC/PEG) composite films with PEG concentrations in the range of 0–30% w/w with selective Bragg reflection at wavelengths from 440 to 550 nm are prepared. A modular device comprised of a dip‐coated birefringent CNC‐glass sample sandwiched between two CNC/PEG‐glass samples shows different responses to light with LCP and to light with right‐handed circular polarization (RCP). The device suppresses selective Bragg reflection from the rear (front) CNC/PEG sample for incident light with LCP (RCP), even when the birefringent film does not meet the condition for a halfwave plate. This behavior resembles the performance of optical diodes for circular polarization. Polarization properties of composite films and optical diodes in terms of degree of polarization and ellipticity are discussed within the Stokes–Mueller formalism. Electromagnetic simulations of Mueller matrices reveal the equivalence of modular and in‐tandem film approaches of optical diodes.

Fabrication of novel printable artificial bone composites used as cartilage scaffolds by an additive manufacturing process

AbstractPolylactic acid (PLA), a biodegradable polymer, has become a major raw material in the field of 3D printing. However, some defects such as high brittleness and average bioactivity limit its application. In this study, a novel 3D printing composite of animal bone powder/polyethylene glycol/polylactic acid was prepared and investigated. The structures and properties of bHA/PEG/PLA composites were compared with commercial micron‐sized hydroxyapatite (mHA) and nano hydroxyapatite (nHA) composites. The study results show that the bHA has the same chemical structure as mHA and nHA, but its average particle size is 390 nm, which is quite different from mHA and nHA. When the PEG content is 14%, the toughness of the PEG/PLA blends is good, and its elongation at break reaches 96.23%. The bending strength, tensile strength, and elongation at break of bHA/PEG/PLA composites reach 25.1 MPa, 16.3 MPa, and 11.32%, respectively, which are all higher than those of mHA/PEG/PLA and similar to those of nHA/PEG/PLA. The bHA/PEG/PLA biological scaffolds prepared by 3D printing show good biocompatibility in cytotoxicity experiments and have good application prospects in bone tissue engineering.

Rapid Production of Nanoscale Liposomes Using a 3D-Printed Reactor-In-A-Centrifuge: Formulation, Characterisation, and Super-Resolution Imaging.

Nanoscale liposomes have been extensively researched and employed clinically for the delivery of biologically active compounds, including chemotherapy drugs and vaccines, offering improved pharmacokinetic behaviour and therapeutic outcomes. Traditional laboratory-scale production methods often suffer from limited control over liposome properties (e.g., size and lamellarity) and rely on laborious multistep procedures, which may limit pre-clinical research developments and innovation in this area. The widespread adoption of alternative, more controllable microfluidic-based methods is often hindered by complexities and costs associated with device manufacturing and operation, as well as the short device lifetime and the relatively low liposome production rates in some cases. In this study, we demonstrated the production of liposomes comprising therapeutically relevant lipid formulations, using a cost-effective 3D-printed reactor-in-a-centrifuge (RIAC) device. By adjusting formulation- and production-related parameters, including the concentration of polyethylene glycol (PEG), temperature, centrifugation time and speed, and lipid concentration, the mean size of the produced liposomes could be tuned in the range of 140 to 200 nm. By combining selected experimental parameters, the method was capable of producing liposomes with a therapeutically relevant mean size of ~174 nm with narrow size distribution (polydispersity index, PDI ~0.1) at a production rate of >8 mg/min. The flow-through method proposed in this study has potential to become an effective and versatile laboratory-scale approach to simplify the synthesis of therapeutic liposomal formulations.

Different Dissolution Molecular Pathways of Azilsartan Crystals with Different Forms Revealed by In Situ Atomic Force Microscopy.

Here, using in situ atomic force microscopy (AFM), the dissolution behaviors and dissolution molecular pathways of two azilsartan crystals, the isopropanol solvate (AZ-IPA), and form I (AZ-I), in pure water and 6-30% poly(ethylene glycol) (PEG) aqueous solutions are revealed. The dissolution behaviors of step retreat and etch pit formation are observed on the (100) faces of the two crystals, with a single step corresponding to one molecular monolayer in crystal structures. Etching rates of pits increase with PEG concentration. Furthermore, our results show that AZ-IPA dissolves by the direct detachment of molecules from the step front to solution. Such a mechanism remains even when the PEG concentration changes. However, AZ-I dissolves primarily by the surface diffusion mechanism involving molecular detachment from the step front at first and then diffusion over the terraces before desorption into solution. PEG promotes the dissolution of AZ-I crystals by favoring the molecular detachment from the step front.

Aqueous two-phase extraction and characterization of thermotolerant alkaliphilic Cladophora hutchinsiae xylanase: biochemical properties and potential applications in fruit juice clarification and fish feed supplementation

Xylanase finds extensive applications in diverse biotechnological fields such as biofuel production, pulp and paper industry, baking and brewing industry, food and feed industry, and deinking of waste paper. Here, polyethylene glycol (PEG)-phosphate aqueous two-phase system (ATPS) was applied for the purification of an alkaline active and thermotolerant xylanase from a marine source, Cladophora hutchinsiae (C. hutchinsiae). In the purification process, the effects of some experimental factors such as PEG concentration and PEG molar mass, potassium phosphate(K2HP04) concentration, and pH on xylanase distribution were systematically investigated. Relative enzymatic activity and purification factor obtained were 93.21% and 7.18, respectively. A single protein band of 28 kDa was observed on SDS-PAGE. The optimum temperature and pH of xylanase with beechwood xylan were 30 °C and 9.0, respectively. The Lineweaver-Burk graph was utilized to determine the K m (4.5 ± 0.8 mg/mL), V max (0.04 ± 0.01 U) and k cat (0.001 s−1) values of the enzyme. It was observed that the purified xylanase maintained 70% of its activity at 4 °C and was found stable at pH 4.0 by retaining almost all of its activity. Enzymatic activity was slightly enhanced with Na+, K+, Ca2+ and acetone. The highest increase in the reducing sugar amount was 53.6 ± 3.8, for orange juice at 50 U/mL enzyme concentration.

Drought stress induced by polyethylene glycol (PEG) in local maize at the early seedling stage

Drought stress adversely impacts growth, crop production, reproductive organ development, and yield characteristics in maize. As a drought-sensitive crop, maize (Zea mays L.) shows considerable varietal differences. A study was conducted at the Tissue Culture Laboratory, Department of Biology, Faculty of Mathematics and Natural Sciences, University of North Sumatra, Medan, Indonesia in order to identify drought-tolerant maize varieties. During germination and early seedling growth, 16 local accessions were evaluated for drought tolerance. Based on local climate and soil conditions, these specific accessions were chosen. The varieties were tested against five levels of drought stress imposed by Polyethylene glycol 6000 (PEG-6000) at 10, 20, 30, 40, and 50%. An experiment with three replications was conducted using a completely randomized design. In the study, local maize accessions (BI3, SB5, DS2, and MN3) and the hybrid variety (H) showed the capability of tolerating drought stress. Generally, germination time, germination percent and vigor index, root and shoot length, shoot ratio, and fresh and dry weight were decreased by increasing PEG concentrations (up to 50%). According to ANOVA results, shoot water content was not significantly affected by the PEG, nor was the interaction between the PEG and the accessions. The root water content, however, was significantly affected by PEG, and the interaction between PEG and accessions. Although interactions between accessions with low PEG concentrations improved germination characteristics, the root histology of the accessions varied. According to drought tolerance indexes, five maize accessions are drought-tolerant, including H (0.683), SB5 (0.617), DS2 (0.565), MN3 (0.512), and BI3 (0.504). The drought-tolerant varieties are recommended in regions with low rainfall or low water sources since they are less water-intensive and produce higher yields.

Optimizing Priming Concentration and Duration of PEG 6000 for Improving Seed Germination and Vigour in Chickpea (Cicer arietinum L.)

This study was undertaken with different concentration and duration of PEG-6000 to observe the effect of germination and seedling vigour in chickpea seeds. The experiment was conducted in seed testing laboratory, Department of Seed Science and Technology, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal, India during 2020-2021 following Complete Randomized Block Design with three replications in order to standardize the appropriate concentration and duration while soaking the seeds within PEG-6000 solution for screening a range of duration concentrations viz, 10 g liter-1 for 6 hrs, 10 g liter-1 for 8 hrs, 10 g liter-1 for 10 hrs, 15 g liter-1 for 6 hrs , 15 g liter-1 for 8 hrs, 15 g liter-1 for 10 hrs, 20 g liter-1 for 6 hrs, 20 g liter-1 for 8 hrs, 20 g liter-1 for 10 hrs, 25 g liter-1 for 6 hrs, 25 g liter-1 for 8 hrs, 25 g liter-1 for 10 hrs. Untreated dry seeds were considered as control. It was found that all the priming treatments showed significance difference in overall including the control. The best performer or the better result was shown by T8 which is 20 gm/ liter solution with the soaking duration of 8 hrs. It was highest performer in germination percentage (93.77), root length (6.57 cm), shoot length (16.57 cm), seedling fresh weight (1.66 g), seedling dry weight (0.14 g), seedling vigour index I (2137.07), time to 50% germination (2.33 days) and germination index (77.82). This study showed that seed priming with osmotic solution could improve some seedling parameters in chickpea. In seed priming, its simplicity such as no requirements for extensive equipment and chemicals could be used method for overcoming problems related to a poor germination and further seedling establishment and helps in sustaining agriculture with a cost effective approach and with the help of seed priming treatments which are non-toxic and from eco-friendly sources.

Preparation of Electrospun Composite PEG/PVP Phase-Change Nanofibers and their Application in Cigarette Cooling Filters

Abstract Composite phase-change nanofibers were prepared by electrospinning with polyethylene glycol (PEG) as the phase-change material (PCM) and polyvinylpyrrolidone (PVP) as the carrier matrix. The high PEG content endowed the nanofibers with an excellent cooling effect and significantly reduced the smoke temperature. For PEG70/PVP nanofibers, the smoke temperature can be decreased 45℃ at the 8th puff, and be kept below 45℃. The cooling test proved that the electrospun PEG/PVP phase-change nanofibers exhibited a desirable cooling performance, improving the comfort of cigarette products. And the composite PEG/PVP phase-change nanofibers present great potential as the cooling cigarette filter material for HnB tobacco application.

Effect of Composition and Size on Surface Properties of Anti-Cancer Nanoparticles.

Liposomal formulations offer significant advantages as anticancer drug carriers for targeted drug delivery; however, due to their complexity, clinical translation has been challenging. In addition, liposomal product manufacturing has been interrupted in the past, as was the case for Doxil® (doxorubicin hydrochloride liposome injection). Here, interfacial tension (IFT) measurements were investigated as a potential physicochemical characterization tool to aid in liposomal product characterization during development and manufacturing. A pendant drop method using an optical tensiometer was used to measure the interfacial tension of various analogues of Doxil® liposomal suspensions in air and in dodecane. The effect of liposome concentration, formulation (PEG and cholesterol content), presence of encapsulated drug, as well as average particle size was analyzed. It was observed that Doxil® analog liposomes demonstrate surfactant-like behavior with a sigmoidal-shape interfacial tension vs. concentration curve. This behavior was heavily dependent on PEG content, with a complete loss of surfactant-like behavior when PEG was removed from the formulation. In addition to interfacial tension, three data analyses were identified as able to distinguish between formulations with variations in PEG, cholesterol, and particle size: (i) polar and non-polar contribution to interfacial tension, (ii) liposomal concentration at which the polar and non-polar components were equal, and (iii) rate of interfacial tension decay after droplet formation, which is indicative of how quickly liposomes migrate from the bulk of the solution to the surface. We demonstrate for the first time that interfacial tension can be used to detect certain liposomal formulation changes, such as PEG content, encapsulated drug presence, and size variability, and may make a useful addition to physicochemical characterization during development and manufacturing of liposomal products.

Structure and thermal behaviour of different concentration PEG loaded PVA nanofibers

Poly vinyl alcohol (PVA) has established its credibility in the fields of filtration, biomedical and pharmaceutical areas. In this paper different concentration of poly (ethylene) glycol were added to PVA to prepare gel and its nano fibres. PEG is water soluble similar to PVA can give a uniform gel and a strong intermolecular bonding can be achieved by the addition of PEG in PVA. Fibres were prepared by having high wt.% of PEG loaded PVA nano fibres. Nano fibre mat having 0, 0.2,0.4 and 0.6 g PEG having low molecular weight was added in the 8.6 wt.% PVA solution and then fibres were prepared by using electro spinning technique. Nano fibres so prepared were characterised by SEM, XRD and DSC. SEM results reveal that increase of PEG concentration separated the nano fibres and increased the gap of the mesh size. SEM micro graphs depicts that produced nano fibres are homogenous in nature and there were no apparent gap between the PVA and PEG nano fibre. It may be explained that due to the high electric potential developed during the electro spinning process which helped the nano fibres to get stretched XRD patterns exhibited the crystal size increased on adding PEG in the PVA gel. Effect of PEG addition on Tm of PVA nano fibres has been determined by running their DSC scans. An additional peak of 158.13°C is observed for the sample having 0.4 g PEG. Melting temperature shifted from 215° C to 219°C due to increase in crystal size of PEG added PVA nano fibres.

Study of the Thermal and Mechanical Properties of the Hydrophilic Blend Material Polyhydroxyethyl Methacrylate/Polyethylene Glycol: Hydrogen Bonding Analysis

A hydrophilic blend material is a material that can take up an important quantity of water, which makes it useful in various applications such as tissue engineering, contact lenses, and drug delivery. In this study, the polymeric blend material polyhydroxyethyl methacrylate/polyethylene glycol (pHEMA/PEG) was prepared through a UV photo-polymerization reaction; hexanediol diacrylate (HDDA) and Darocur 1,173 were used, respectively, as a cross-linking agent and a photoinitiator. The main objective of this investigation was to evaluate the impact of the PEG content on the thermal and mechanical properties of the crosslinked pHEMA/HDDA. Many analytical techniques, including Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA), were used, to analyze the bonding vibrations, the glass transition temperature (Tg), and the elastic and loss moduli, respectively. The complex viscosity was analyzed by a rheometer. The swelling and deswelling behavior of the crosslinked pHEMA/PEG in distilled water were studied over time. It was found that the PEG increased the polymerization rate of the HEMA monomer, and a significant decrease in the glass transition temperature was observed with increasing PEG quantity in the blend material, confirming its plasticizing effect. The mechanical, swelling kinetics, and rheology results showed a threshold effect at 1 wt.% for PEG. The docking analysis showed that there was more hydrogen bonding between the pure pHEMA’s chains, but the integration of PEG decreased the number of hydrogen bonds, which gave flexibility to the blend material, hence; this theoretical conclusion well agreed with the experimental results.

Characterization of drought stress-mitigating Rhizobium from faba bean (Vicia faba L.) in the Chinese Qinghai-Tibet Plateau.

Rhizobium-driven symbiotic nitrogen-fixation in legumes not only benefits the growth but also enhances the stress tolerance of plants. Isolating and characterizing efficient, drought-tolerant rhizobia is a central goal for improving crop yields in arid regions. Here, we phylogenetically and biochemically characterized a novel strain of Rhizobium ('QHCD11') sampled from the root nodules of faba beans growing in an arid agricultural area in Qinghai-Tibet. We further tested the drought tolerance of the strain as well as of 'Qingcan 14' faba bean seedlings inoculated with it. Biochemical characterization involved bromothymol blue (BTB) tests, carbon metabolic profiling (Biolog GENIII), DNA-DNA hybridization (dDDH) assays, average nucleotide identity (ANI) analyses, and 16S rRNA sequencing. The result indicated that strain 'QHCD11' likely belongs to the Rhizobium indicum species. Drought stress tolerance was assessed by exposure to polyethylene glycol (PEG-6000) at concentrations of 0, 10, 15, and 20%. Increasing concentrations of PEG-6000 tended to result in decreased growth of 'QHCD11', although the strain performed better at 20% PEG 6000 than at 15%. Inoculation of drought-stressed faba bean seedlings with strain 'QHCD11' improved root vitality, chlorophyll content, antioxidant enzyme activities, and plant height. We suggest that inoculation of faba beans with 'QHCD11' is an environmentally sound strategy for mitigating crop drought stress in arid and semi-arid regions. In addition, the results presents here will benefit future studies into faba bean-rhizobia symbioses under drought stress.

Matrix Effects of Urine Marker Substances in LC-MS/MS Analysis of Drug of Abuse.

Analysis of drug abuse is frequently performed using high-performance liquid chromatography with an MS/MS detector and electrospray ionization. In this context, matrix effects, like signal reduction by ion suppression of individual analytes, play an important role. In this study, the authors evaluated the matrix effect caused by polyethylene glycol (PEG) with chain lengths ranging from 6 to 12 repeating units in drug analysis by LC-MS/MS. Selected chain lengths were used in the Ruma urine marker system. Amphetamines, opiates, opioids, antidepressants, psychotics, benzodiazepines, z-substances, and individual drugs, including THCCOOH, cocaine, LSD, and some of their metabolites were investigated. The matrix effect was investigated at PEG concentrations of 500 mcg/mL and 20 mcg/mL. The effect of each PEG molecule was determined. Furthermore, the effects of different common sample preparations on the PEG matrix effects were evaluated. There was a strong correlation between the retention time of PEG and the drug that was ion-suppressed by PEG. The matrix effect decreased to the point where it was within an acceptable range at the lower PEG concentrations investigated in this study. Matrix effects were observed for drugs with approximately the same retention times as the individual PEGs. The influence of the different workup methods was not as clear, which may be because of the similar solubilities of the PEGs and some analytes. At low PEG concentrations, the matrix effect was always below 60%, except for nortilidine. All the drugs were detectable. The effect on quantification was less than 15% for substances with deuterated analytes as internal standards and less than 32% for analytes without their own internal standards.

Assessment of Gus Expression Induced by Anti-Sense OsPPO Gene Promoter and Antioxidant Enzymatic Assays in Response to Drought and Heavy Metal Stress in Transgenic Arabidopsis thaliana

Abiotic stresses, including drought and heavy metals, are detrimental to plant growth and development and enormously reduce agricultural yields. Plants may quickly change their transcriptome in response to various stressful conditions. Plants develop many defense mechanisms to respond to various stresses that can be classified into morphological, physiological, and biochemical responses. Polyphenol oxidases (PPOs) are one of the self-protective enzymes found in plants except for Arabidopsis. Currently, drought and heavy metals were applied exogenously to transgenic A. thaliana lines (transformed with Oryza sativa PPO promoter fused to the GUS reporter gene). The current study mainly focused on the systematic pathway by which plants respond to stressors. The aim of this study is to investigate the effect/expression of PPO and antioxidant defense system against abiotic stresses. A. thaliana was treated with different concentrations of polyethylene glycols. At 30% PEG, maximum fold induction (1.9) was seen after 12 h. Overall, various concentrations (5%, 20%, and 30%) induced PPO expression after 6, 12, and 24 h. Moreover, three different concentrations of Cu (50 µM, 100 µM, 200 µM) and Ni (50 µM, 100 µM, 200 µM) for 6, 12, and 24 h were also applied. It was observed that the expression profiling of the OsPPO promoter induced GUS gene expression in response to Cu and Ni treatments. The maximum fold induction (15.03) of GUS was observed in 100 µM of Cu after 24 h. In the case of Ni, maximum fold induction of (7.78) was observed at 100 µM after 24 h. So, both Cu and Ni showed a similar pattern of induction at 100 µM after 24 h. In conclusion, the efficiency of the PPOGUS promoter can be operated to assess the response of plants to various abiotic stimuli.

Salt and Water Stress Tolerance in Ipomoea purpurea and Ipomoea tricolor, Two Ornamentals with Invasive Potential

Invasive plants pose a significant threat to biodiversity, especially under the current unstable climatic conditions. This study aimed to test the salt and drought tolerance of two ornamental species of the genus Ipomoea during germination and vegetative growth. Germination tests were performed in the presence of increasing NaCl concentrations or iso-osmotic PEG concentrations—to mimic the osmotic stress caused by drought. Both species showed great invasive potential because of their high seed germination percentages and rapid germination under control (distilled water) and salt stress conditions, up to 200 mM NaCl. Germination and early seedling development were more affected in the presence of PEG. Subsequently, water stress (complete withholding of irrigation) and salt stress (watering with 100 mM and 200 mM NaCl) treatments were applied to young plants for three weeks, when all plants were harvested, to determine several morphological and biochemical parameters. Both species were sensitive to water deficit but relatively resistant to salt stress. Their salt stress responses were similar, based mainly on the inhibition of Na+ and the activation of K+ transport from roots to leaves and the uptake and accumulation of Ca2+; however, I. tricolor showed a slightly higher tolerance to salt stress than I. purpurea. Although I. tricolor has only been locally reported as invasive and is generally considered a ‘low-risk’ species, our results indicate that it may have an invasive potential even higher than I. purpurea, a recognised invasive weed, spread into areas with moderate salinity, affecting agricultural land or natural habitats of ecological interest.