High Salinity Conditions Research Articles

Efficient activation of peroxymonosulfate by N-doped waste herb senna obtusifolia biochar for degrading NPX: Synergistic effect of carbonyl and nitrogen sites

In this work, waste herb senna obtusifolia was utilized as the biochar precursor, and a N-doped biochar (NSOBC-6) was prepared to activate peroxymonosulfate (PMS) for degrading Naproxen (NPX). NSOBC-6 exhibited superior catalytic performance in activating PMS, which could degrade NPX completely within 60 min. The NSOBC-6/PMS system also had good reusability and effectiveness under a wide range of pH values and high salinity conditions. The significant contribution of singlet oxygen (1O2) and superoxide radicals (O2•−) in NPX degradation was revealed. The results of XPS and DFT calculations indicated C=O, pyridinic-N and graphite-N participated as catalytic sites in the degradation of NPX. The differences in electron density and the ELUMO-EHOMO (ΔELUMO-HOMO) gap were induced by N doping, enhancing the PMS activation capacity of NSOBC-6. This work presented a strategy to convert waste herbal into functional biochar materials, which was of great significance for the development of green and efficient catalysts.

Extraction, characterization, and evaluation of galactomannan from Barbatimão Verdadeiro as a potential additive for enhanced oil recovery fluids

Polymers play a crucial role in enhanced oil recovery (EOR) by increasing the viscosity of injection fluids and enhancing oil displacement. The widely used polymer, partially hydrolyzed polyacrylamide (HPAM), faces performance degradation in high-salinity and high-temperature environments. This study explores galactomannan from Stryphnodendron polyphyllum seeds as an alternative viscosifying agent for EOR fluids. An extraction process for galactomannan from Barbatimão Verdadeiro seeds was developed, yielding 23.3% m/m. The biopolymer was characterized using Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), and size exclusion chromatography (SEC). Rheological behavior was tested in brines of different salinities, and injectivity/filterability tests were performed following API RP 63:1990 standards. The galactomannan obtained from Stryphnodendron polyphyllum exhibited a mannose-to-galactose ratio of 1.32. Rheological analysis showed pseudoplastic behavior, with viscosities of 38 cP in brine solutions at 7.37 s−1 and 60 °C. Filterability tests demonstrated satisfactory injectivity with factors of 1.09 (8 µm) and 0.67 (1.2 µm). Compared to HPAM, galactomannan exhibited superior viscosity retention in high-salinity conditions, where HPAM dropped to 6 cP. The galactomannan extracted from Stryphnodendron polyphyllum seeds is a promising biopolymer for EOR applications, offering superior performance under harsh conditions compared to traditional HPAM. Its resilience to high salinity and temperature makes it a viable alternative for pre-salt and offshore fields, contributing to more sustainable and efficient oil recovery.

Polymers marry with carbon nanospheres: A promising strategy to develop high-performance filtrate reducer

Polymeric filtrate reducers have limited uses under high temperature and salinity conditions. The incorporation of nanoparticles to polymeric networks is a popular and effective method for creating high-performance filtrate reducers. However, present nanofillers are costly, have negative environmental consequences, and are difficult or impossible to disseminate. Herein, a simple hydrothermal process using low-cost and renewable glucose as raw ingredients resulted in hydroxy-rich carbon nanospheres (CNs). After modification by acryloyl chloride, the CNs were copolymerized with acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, and sodium p-styrene sulfonate. The obtained CNs-doped polymers (CAAS) were able to maintain high viscosity and colloidal stability even after salt contamination and high temperature aging. CAAS-based drilling fluids can tolerate temperatures of up to 240 °C under 30 % NaCl conditions. The API filtration loss (FLAPI) and the high-temperature high-pressure filtration loss (FLHTHP) were 10 and 63.5 mL, respectively. Considering the low-cost and renewable raw materials, high dispersibility and high compatibility of CNs as well as significant improvement in thermal-resistance and salt-tolerance, this work provides a simple yet effective approach to developing high-performance filtrate reducers for complex geological conditions.

Utilization of High-Salinity Crude Glycerol Byproduct from Biodiesel Production for Biosynthesis of γ-Aminobutyric Acid in Engineered Halomonas elongata

As the development of renewable energy has become imperative, biodiesel fuel (BDF) has been used as renewable biofuel with the advantage of having lower levels of greenhouse gas emissions. However, the transesterification reaction that produces BDF generates a high-salinity crude glycerol (CG) byproduct, which is difficult to recycle. Halomonas elongata is a moderately halophilic bacterium being used as a cell factory due to its ability to assimilate varieties of substrates for growth in high-salinity conditions. Previously, we engineered a recombinant H. elongata GOP-Gad to biosynthesize and accumulate γ-aminobutyric acid (GABA) as a high-value product. Here, we tested the ability of H. elongata GOP-Gad to use CG as a substrate for cell growth and GABA production. The CG byproduct was obtained from a BDF facility in Unzen City, Nagasaki, Japan, where geothermal energy catalyzed BDF production from waste cooking oil and biomethanol. Prior to use as the sole carbon (C) source in culture media, the CG byproduct was partially purified to remove soap substances and other impurities. Finally, we showed that H. elongata GOP-Gad could grow and accumulate GABA up to 28 μmol/g cell fresh weight in a minimal M63 medium containing 7% w/v NaCl with 4% w/v glycerol from the partially purified CG as a C source and 15 mM (NH4)2SO4 as a nitrogen (N) source. This result demonstrates a new circulatory bioprocess of C and N, in which H. elongata GOP-Gad can use partially purified CG and (NH4)2SO4 as the sole C and N sources for growth and GABA production.

Insights into sulfamethazine degradation by peroxymonosulfate activation using H2 reduced hematite in high-salinity wastewater: Performances and mechanisms

Sulfamethazine (SMT) is recognized as a persistent, bioaccumulate, and toxic antibiotic pollutant that is difficult to be completely eliminated through traditional wastewater treatment methods. Although advanced oxidation processes (AOPs) utilizing peroxymonosulfate (PMS) have demonstrated potential in degrading SMT, the lack of inexpensive and efficient PMS activators remains a significant obstacle for its practical application. In this study, we present the synthesis of a highly effective PMS activator, the naturally-occurring minerals-based material − H2– reduced hematite (HRH), on an industrial scale using a fluidized bed reactor. Impressively, within the PMS AOPs system, the synthesized HRH catalyst not only achieves 99.3 % degradation of SMT within 20 min, demonstrating a remarkable 10-fold increase in the degradation rate compared to pristine hematite, but also showcases excellent recyclability and durability. Additionally, this HRH/PMS system were proved to effectively remove SMT under high-salinity conditions. More importantly, through systematic characterization and theoretical calculations, an in-depth investigation into the primary activation mechanism and degradation pathway in this reaction process is provided. This work provided a highly feasible strategy for the application of natural mineral-based catalyst for the degradation of pollutants via PMS activation in high-salinity wastewater.

Insights into the Epigenetic Basis of Plant Salt Tolerance.

The increasing salinity of agricultural lands highlights the urgent need to improve salt tolerance in crops, a critical factor for ensuring food security. Epigenetic mechanisms are pivotal in plant adaptation to salt stress. This review elucidates the complex roles of DNA methylation, histone modifications, histone variants, and non-coding RNAs in the fine-tuning of gene expression in response to salt stress. It emphasizes how heritable changes, which do not alter the DNA sequence but significantly impact plant phenotype, contribute to this adaptation. DNA methylation is notably prevalent under high-salinity conditions and is associated with changes in gene expression that enhance plant resilience to salt. Modifications in histones, including both methylation and acetylation, are directly linked to the regulation of salt-tolerance genes. The presence of histone variants, such as H2A.Z, is altered under salt stress, promoting plant adaptation to high-salinity environments. Additionally, non-coding RNAs, such as miRNAs and lncRNAs, contribute to the intricate gene regulatory network under salt stress. This review also underscores the importance of understanding these epigenetic changes in developing plant stress memory and enhancing stress tolerance.

Surfactant-enhanced dispersion stability of cellulose nanocrystals and enhanced oil recovery performance

Cellulose nanocrystals (CNCs) have attracted more and more attention in EOR. CNCs are abundant and renewable, with nanoscale dimensions, excellent rheological properties, and easy-to-modify surface properties. However, the colloid stability of CNCs under high salinity conditions is poor, which limits their application in enhanced oil recovery (EOR). In order to improve the stability of CNCs in the salt environment, the effect of the mixed system of sodium dodecyl benzenesulfonate (SDBS) and polyoxyethylene sorbitan monooleate (Tween 80) on the dispersion stability of CNCs in the presence of different valence salt ions was investigated systematically. The dispersion stability of CNCs was investigated by using the ζ-potential and dynamic light scattering (DLS) techniques. The mixed surfactants improved the dispersion stability of CNCs within the studied salt ion concentration range (Na+ ≤ 300 mM, Ca2+ ≤ 10 mM, Mg2+ ≤ 10 mM). The stabilization mechanism of CNCs was explained by the electrostatic effect and spatial stabilization effect. In the presence of salt ions, the adsorption behavior of mixed surfactants on the surface of CNCs in the presence and absence of crude oil was revealed through molecular dynamics (MD) simulations. Microscopic displacement experiments indicated that due to the small particle size of CNCs in salt environments, the pores were not blocked, resulting in a significant improvement in the oil displacement performance.

Species identification and pollination biology of an economically important true halophyte, Salicornia brachiata Roxb.

Members of the genus Salicornia have gained a global attraction due to their ability to thrive under high saline conditions and as potential candidates in saline agriculture. However, it has been a taxonomically challenging genus for decades since the members show plastic responses to extreme environmental conditions and due to incongruences between morphological and molecular identification methods. While only a handful of commercially grown Salicornia species are fully described, most of the species including S. brachiata, a native species in the Indian sub-continent, Myanmar, and Sri Lanka are poorly described. With the potentials in adapting S. brachiata in saline agriculture, the aim of this study was to establish a morphology and DNA barcode-based species delineation system and to study pollination biology for future crop improvement projects. Tentatively identified S. brachiata plant samples were collected from two populations in Sri Lanka and completely described. GenBank lacked authenticated barcode data for S. brachiata except for one chloroplast genome to which the matK sequence obtained in the present study matched with 100 % identity. For the first time, well defined sequences of three barcode regions, ITS, ETS and matK, of S. brachiata were made available for accurate species identification. Reproductive dynamics in different parts of the inflorescence was studied. A facultative xenogamous mating system was recorded for the first time in the genus and while the lower florets in the cladode showed a preference towards outcrossing, the upper florets displayed adaptations for selfing. Data could be effectively utilized in future Salicornia breeding programs.

Nanomodified bamboo (Phyllostachys aurea) biomass: its adsorbent features in the removal of dyes from water under high salinity conditions.

The effluent generated by textile industries is among the most polluting to the environment. Dyes such as methylene blue (MB) and indigo blue (IB) are used in cotton dyeing. This work proposes to evaluate the potential of in natura (BIN) and nanomodified (BNP) bamboo (Phyllostachys aurea) biomass as biosorbents for the removal of MB and IB dyes in an aqueous medium under high salinity conditions. These materials were characterized by Fourier transform infrared (FTIR) and X-ray (XRD) spectroscopies and scanning electron microscopy (SEM) to investigate their morphology and interaction with the dyes and the nanoparticles. The FTIR spectra revealed the existence of hydroxyl and carbonyl groups, ethers, phenols, and aromatic compounds, indicating the presence of a lignocellulosic structure. XRD and SEM analyses confirmed the effectiveness of the nanocomposite synthesis process. The dyes were quantified by ultraviolet-visible spectroscopy (UV/Vis). The material's pH at the point of zero charge (pHPZC) was 5.52 (BIN) and 4.84 (BNP), and the best IB and MB sorption pH were 3.0 and 9.0 for BNP, respectively, employing 30min of contact time. The material sorption capacity (Qexp) was assessed using batch procedures, in which 100-1000mg/L dye concentrations were tested with a 0.5g/L adsorbent dose. The dye's Qexp for BIN and BNP was 25.41 ± 0.58 and 23.42 ± 0.07mg/g (MB) and 84.26 ± 1.1 and 130.81 ± 0.20mg/g (IB), respectively. The kinetic model that best fit BNP experimental data was the pseudo-2nd-order with r2 = 0.99868 (MB) and r2 = 0.99873 (IB), and Freundlich, D-R, and Temkin isotherms best fit the dye sorption data. The bamboo nanomodification facilitates the biosorbent removal from the medium after sorption, enabling large-scale studies and industrial applications-the investigated materials provided promising adsorption features for removing contaminant dyes in saline water.

MpPUB9, a U-box E3 ubiquitin ligase, acts as a positive regulator by promoting the turnover of MpEXO70.1 under high salinity in Marchantia polymorpha.

Marchantia polymorpha, occupying a basal position in the monophyletic assemblage of land plants, displays a notable expansion of plant U-box (PUB) proteins compared with those in animals. We elucidated the roles of MpPUB9 in regulating salt stress tolerance in M. polymorpha. MpPUB9 expression was rapidly induced by high salinity and dehydration. MpPUB9 possessed an intact U-box domain in the N-terminus. MpPUB9-Citrine localized to punctate structures and was peripherally associated with microsomal membranes. Phenotypic analyses demonstrate that the hyponastic and epinastic thallus growth phenotypes, which were induced by the overexpression and suppression of MpPUB9, may provoke salt stress-resistant and -susceptible phenotypes, respectively. MpPUB9 was also found to directly interact with the exocyst protein MpEXO70.1, leading to its ubiquitination. Under high-salinity conditions, though the stability of MpPUB9 was dramatically increased, MpEXO70.1 showed slightly faster turnover rates. Transcriptome analyses showed that salt treatment and the overexpression of MpPUB9 co-upregulated the genes related to the modulation of H2O2 and cell wall organization. Overall, our results suggest that MpPUB9 plays a crucial role in the positive regulation of salt stress tolerance, resulting from its interaction with MpEXO70.1 and modulating turnover of the protein under high-salt conditions via the coordination of UPS with autophagy.

Slow release of surfactant by smart thermosensitive polymer-functionalized mesoporous silica for enhanced oil recovery: Synthesis and characterization

The efficiency of surfactant flooding can be improved through slow-release technology, which enables stimuli-sensitive and gradual release of surfactant. In this study, we synthesized a novel nanocomposite capsule composed of mesoporous silica functionalized with thermosensitive poly N-vinyl caprolactam (PNVCL). Well-optimized nanocarriers were synthesized by conducting sensitivity analyses on key synthesis parameters such as pH, reaction duration, and hydrophobic phase, resulting in hydrodynamic diameters ranging from 47 to 109 nm. Characterization of the nanocarrier structure was performed using dynamic light scattering (DLS), Brunauer–Emmett–Teller (BET) analysis, and field emission scanning electron microscopy (FESEM), while Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and energy-dispersive X-ray spectroscopy (EDS) were employed to analyze the nanocarrier composition. Poly N-vinyl caprolactam (NVCL)-functionalized mesoporous silica exhibited high surfactant loading (approximately 52 % w/w) and a large specific surface area (542.88 m2/g), featuring ink-bottle pores. Additionally, it demonstrated thermosensitive behavior, with the lower critical solution temperature of 39 °C. Gradual release of cetyltrimethylammonium bromide (CTAB) was observed in both deionized water and formation brine, with release rates increasing with temperature. Overall, the synthesized nanocomposite carrier holds significant potential as an ideal candidate for effectively controlling the release of surfactants in reservoirs subjected to high-temperature and high-salinity conditions.

Mono- and di-rhamnolipids mixtures from Pseudomonas aeruginosa for use in extreme conditions of pre- and post-salt oil reservoirs compared with synthetic surfactants

Rhamnolipids are multipurpose molecules known as natural glycolipid biosurfactants that are often biosynthesized by Pseudomonas aeruginosa strains. They are readily biodegradable, have less impact on the environment and are less toxic than conventional surfactants. They can be applied in ex situ microbial enhanced oil recovery. However, there is still a lack of knowledge concerning the drastic environmental conditions of post and pre-salt reservoirs. In this study, different mixtures with different proportions of homologs of rhamnolipids from two genetically modified strains (GMOs) of P. aeruginosa and a non-GMO strain compared to commercial surfactants (Arquad C-50 and/or Ultrasperse II®) regarding their efficiency under high pressure, temperature and salinity conditions. Wettability reversal and interfacial tension tests were performed together with central composite rotational designs. Both genetically modified P. aeruginosa strains produced mainly di-rhamnolipids, whereas the non-GMO strain produced approximately 50 % mono- and 50 % di-rhamnolipids. Rhamnolipids and Arquad C-50 reversed 100 % of the wettability under pre-salt and post-salt conditions, whereas Ultrasperse II® achieved 73.3 % and 34.2 % (100 ppm) wettability, respectively. Interfacial tension presented the lowest values for rhamnolipids, with values of 0.4 mN/m and 0.5 mN/m, whereas Ultrasperse II® presented values of 2.6 and 2.5 mN/m, respectively under post-salt and pre-salt conditions at the +1 level of the tested variables. All rhamnolipid congeners tested here were more effective under post and pre-salt reservoirs conditions than commercial surfactants, thus expanding their potential for use not only in environmental bioremediation but also in oil industry processes.

Comparative evaluation of adsorptive and repulsive separation using cellulose nanofiber/calcium alginate composite hydrogel filtration membranes with improved degradability

Among several approaches to address hard-to-manage dye wastewater, adsorption is one of the widely used methods, but the usage of these adsorbents can be constrained by their high material and process costs depending on the adsorbent materials as well as handling a large amount of adsorbents in a bulk solution. To overcome the problems, hydrogel membranes have recently attracted much attention because they can provide several strengths such as adsorption removal, confined adsorption sites, and filtration separation. However, to the best of our knowledge, it is still quite rare to find an in-depth comparative evaluation of adsorptive removal and repulsive separation in hydrogel membrane filtration. Herein, this study aims to bridge the gap between existing knowledge and undisclosed phenomena. Through a thorough comparative evaluation of adsorptive removal and repulsive separation in hydrogel membrane filtration, we found that repulsive separation was more suitable and sustainable than adsorptive removal because it was free from internal membrane fouling, adsorption sites’ saturation, and the cake layer formation on the surface. As a result, the hydrogel membranes could maintain excellent real-time separation performance while mitigating severe flux and rejection decline. Furthermore, we significantly improved the degradability of the spent hydrogel membrane under high saline conditions by 6.3 times compared to the control membrane by fine-tuning the structural properties via dual crosslinking, while maintaining the mechanical properties during filtration. It was possible due to the extended distance between polymer chains by dual crosslinking, reducing the burden imposed by plastic waste generated from the spent membrane.

Experimental study on the optimization and stability of methane foam systems under high-temperature, high-pressure, and high-salinity conditions

Experimental study on the optimization and stability of methane foam systems under high-temperature, high-pressure, and high-salinity conditions

Differential effects of salinity and drought on germination and early seedling growth of Parkinsonia praecox

Context Germination and seedling growth are critical stages in the establishment of a species under adverse environmental conditions. Parkinsonia praecox is a species that can establish in soils with high salt concentrations and water deficit conditions. Aims This study focused on the germination and early growth responses of P. praecox seeds exposed to different salinity and water deficit treatments, to understand its distribution and its potential to persist in stressful environments. Methods P. praecox seeds were exposed to solutions containing NaCl (for salinity) and polyethylene glycol (PEG; for water deficit) at a range of potentials −0.4, −0.8, −1.2, −1.5 and −1.9 MPa, and germination and early growth responses were evaluated. Controls were exposed to distilled water treatments (0 MPa). Key results The highest germination was obtained in the distilled water treatment, whereas drought imposed by PEG and salinity caused a decrease in the percentage and speed of germination. Seed germination significantly decreased at 1.2 MPa in the saline treatments but at −0.8 MPa in PEG solutions. However, at −1.2 MPa and higher, the germination rate was higher in PEG-treated seedlings compared to those exposed to NaCl. Considerable early seedling growth was observed in low potentials and high saline conditions. Conclusions The effects of salinity and drought on germination and early growth response of P. praecox contributes to the species’ restricted distribution in arid and saline regions. Implications These findings advance our knowledge of P. praecox responses under stressful conditions, highlighting this woody species’ potential as a candidate in the rehabilitation of degraded environments.

Variation of Elemental Composition of Leaves in Nitraria schoberi L. and N. sibirica Pall. Depending on Edaphic Growth Conditions

A study was conducted about the variation of levels of macro- and microelements in the soil and leaves of two species of the genus Nitraria L. in various habitats in Siberia. New data were obtained on the concentration variations of K, Na, Ca, Mg, Fe, Mn, Zn, Cu, Ni, Li, Sr, and Cd in leaves of N. schoberi L. and N. sibirica Pall. It was found that the salinity of habitats of N. sibirica (up to 3.23%) can exceed salinity of soils under N. schoberi (up to 0.5%) by more than sixfold. Soils of N. schoberi habitats are characterized by lower contents of carbonates (1.0–3.8%) and of physical clay (2–19%) as compared to soils of N. sibirica habitats: 1.2–18.2 and 9–40%, respectively. An increase in the physical-clay content of soil positively correlated with the accumulation of Mg, Cu (p ≤ 0.01), and Mn (p ≤ 0.001) in the plant leaves. The degree of soil salinity was positively associated with the accumulation of Ca, Zn, Sr (p ≤ 0.01), Mg (p ≤ 0.05), and Cd (p ≤ 0.001) in the leaves. An increase in concentration of mobile Na in soil positively correlated with concentrations of Ca, Cu (p ≤ 0.01), and Zn (p ≤ 0.001) in the leaves. In N. sibirica leaves, the concentration of K, Ca, Mg, Fe, Sr, Mn, Zn, and Cu was 1.5–3 times higher than that in N. schoberi leaves. Both species are capable of accumulating very high concentrations of Na (N. schoberi: up to 83.8 g/kg and N. sibirica: up to 77.2 g/kg). In the leaves of N. schoberi plants of immature age, K and Na levels were seven times higher than those in leaves of adult generative plants, whereas Mg and Ca levels were 3–5 times higher. This study should expand the understanding of mechanisms of Nitraria species’ adaptation to high-salinity conditions.

Biohydrogen production from saline wastewater: An overview

The escalating global demand for sustainable energy has propelled the exploration of biohydrogen production with a promising avenue for simultaneously generating clean energy and managing waste effectively. This review mainly focuses on advances in sustainable biohydrogen production from saline wastewater, especially in a process that leverages the unique abilities of halotolerant and halophilic microorganisms adapted to high-salinity conditions. It provides an extensive understanding of various biohydrogen production methods, which are biophotolysis, photofermentation, dark fermentation, and microbial electrolysis. Additionally, this review elaborated on the enzymology of hydrogen production and the impact of salt stress, with a particular emphasis on the adaptive mechanisms of “salt-in” and “compatible solute” strategies. These adaptations are crucial for maintaining enzymatic activity and structural integrity under hypertonic conditions. Through a comprehensive examination of microbial pathways and strategies, this review aimed to furnish foundational insights that will drive future research and technological innovations in biohydrogen production.

Polyhydroxyalkanoates production from cheese whey under near-seawater salinity conditions

Treating saline streams presents considerable challenges due to their adverse effects on conventional biological processes, thereby leading to increased expenses in managing those side streams. With this in consideration, this study explores into the potential for valorizing fermented cheese whey (CW), a by-product of the dairy industry, into polyhydroxyalkanoates (PHA) using mixed microbial cultures (MMC) under conditions of near-seawater salinity (30 gNaCl/L). The selection of a PHA-accumulating MMC was successfully achieved using a sequential batch reactor operated under a feast and famine regime, with a hydraulic retention time of 14.5 h, a variable solids retention time of 3 and 4.5 days, and an organic loading rate (OLR) of 60 Cmmol/(L d). The selected culture demonstrated efficient PHA production rates and yields, maintaining robust performance even under high salinity conditions. During PHA accumulation, a maximum PHA content in biomass of 56.4 % wt. was achieved for a copolymer P(3HB-co-3HHx) with a 3HHx content of 7 %. Additionally, to asses the capacity of the culture to produce polymers with different compositions, valeric acid was supplemented to the real fermented feedstock which resulted in the production of terpolymers P(3HB-co-3HV-co-3HHx) with varied monomeric content and a higher maximum PHA content of 62 % wt. Additionally, this study highlights the potential utilization of seawater as alternative to freshwater for PHA production, thereby enhancing circular economy principles and promoting environmental sustainability.

Integrating Transcriptome and Metabolome Analyses Revealed Salinity Induces Arsenobetaine Biosynthesis in Marine Medaka (Oryzias melastigma).

Marine fish exhibit elevated levels of arsenobetaine (AsB), while the impact and underlying mechanism of salinity on AsB biosynthesis remain inadequately explored. In this study, marine medaka (Oryzias melastigma), typically inhabiting 30‰ high salinity, were gradually acclimated to low salinities of 20, 10, and 0‰. Following acclimation, the fish were exposed to arsenate (As(V)) in their diet for 30 days. Results showed a significant accumulation of total arsenic (As) and AsB concentrations in the muscle and head tissues of the exposed fish, with these accumulations exhibiting a positive correlation with water salinity. Transcriptome analyses revealed that exposure to As(V) at low salinity may disrupt membrane components and induce cytoskeletal injuries, while at high salinity, it triggered oxidoreductase activity and transmembrane transport. Metabolome analyses indicated that low salinity induced osmotic stress, resulting in an increased requirement for amino acids to upload intracellular osmotic equilibrium in O. melastigma. Furthermore, the key organic osmolytes and amino acids, including taurine, l-methionine, guanidinoethyl sulfonate, and N-acetyl-l-aspartic acid, exhibited a negative correlation with the AsB concentration. These findings indicated that salinity can regulate osmotic balance by influencing amino acid synthesis under low salinity and stimulating AsB synthesis under high salinity conditions in O. melastigma. This study provides insights into the impact of high salinity on AsB biosynthesis, the underlying regulatory mechanisms, and implications for managing As(V) risk.

Effect of NaCl Stress on Seedling Parameters of Various Chilli (Capsicum annuum L.) Genotypes and Its Mitigation through Hormonal Priming

Salinity is a major environmental challenge that leads to agricultural land degradation and reduced crop yields worldwide. In chilli (Capsicum annuum L.), high salinity conditions can significantly inhibit seed germination and seedling growth. This study aimed to achieve two main objectives: first, to evaluate the effects of NaCl stress on seedling parameters across various chilli genotypes, and second, to explore the potential of hormonal priming in mitigating salt stress. The experiment was conducted in the Seed Testing Laboratory of the Department of Genetics and Plant Breeding at SHUATS, Prayagraj, using 14 chilli genotypes exposed to varying salt concentrations (0 mM, 75 mM, 100 mM, and 150 mM). The results revealed that higher salt concentrations negatively impacted seedling parameters across all genotypes, with EC-492576 displaying superior salt tolerance. The second part of the study focused on alleviating salt stress through hormonal priming, an approach that enhances seedling quality by improving germination and growth under adverse conditions. Under 150 mM salt stress, 12 treatments were applied, including GA3, salicylic acid, ascorbic acid, and IAA at varying concentrations, with unprimed seeds serving as the control. Among these treatments, salicylic acid at 100 ppm yielded the best results improving key parameters such as germination rate, seedling length, and overall vigour. These findings highlight the potential of salicylic acid priming to improve salt tolerance in chilli. These findings highlight the potential of salicylic acid priming to improve salt tolerance in chilli, paving the way for future research in developing salt-tolerant varieties and informing breeding programs aimed at enhancing agricultural resilience in salt-affected regions.