High Salinity Stress Research Articles

Genetics aspect of vitamin C (Ascorbic Acid) biosynthesis and signaling pathways in fruits and vegetables crops.

Vitamin C, also known as ascorbic acid, is an essential nutrient that plays a critical role in many physiological processes in plants and animals. In humans, vitamin C is an antioxidant, reducing agent, and cofactor in diverse chemical processes. The established role of vitamin C as an antioxidant in plants is well recognized. It neutralizes reactive oxygen species (ROS) that can cause damage to cells. Also, it plays an important role in recycling other antioxidants, such as vitamin E, which helps maintain the overall balance of the plant's antioxidant system. However, unlike plants, humans cannot synthesize ascorbic acid or vitamin C in their bodies due to the absence of an enzyme called gulonolactone oxidase. This is why humans need to obtain vitamin C through their diet. Different fruits and vegetables contain varying levels of vitamin C. The biosynthesis of vitamin C in plants occurs primarily in the chloroplasts and the endoplasmic reticulum (ER). The biosynthesis of vitamin C is a complex process regulated by various factors such as light, temperature, and plant hormones. Recent research has identified several key genes that regulate vitamin C biosynthesis, including the GLDH and GLDH genes. The expression of these genes is known to be regulated by various factors such as light, temperature, and plant hormones. Recent studies highlight vitamin C's crucial role in regulating plant stress response pathways, encompassing drought, high salinity, and oxidative stress. The key enzymes in vitamin C biosynthesis are L-galactose dehydrogenase (GLDH) and L-galactono-1, 4-lactone dehydrogenase (GLDH). Genetic studies reveal key genes like GLDH and GLDH in Vitamin C biosynthesis, offering potential for crop improvement. Genetic variations influence nutritional content through their impact on vitamin C levels. Investigating the roles of genes in stress responses provides insights for developing resilient techniques in crop growth. Some fruits and vegetables, such as oranges, lemons, and grapefruits, along with strawberries and kiwi, are rich in vitamin C. Guava. Papaya provides a boost of vitamin C and dietary fiber. At the same time, red and yellow bell peppers, broccoli, pineapple, mangoes, and kale are additional sources of this essential nutrient, promoting overall health. In this review, we will discuss a brief history of Vitamin C and its signaling and biosynthesis pathway and summarize the regulation of its content in various fruits and vegetables.

Selenium-rich Lactobacillus plantarum alleviates salinity stress in Cyprinus carpio: Growth performance, oxidative stress, and immune and inflammatory responses

Salinity is an important environmental factor that affects the health of aquatic animals, when salinity level above the tolerance threshold can pose a significant threat to the survival of aquatic animals. As a trace element necessary for animal growth, selenium participates in the body’s antioxidant reaction, and protect aquatic animals from oxidative stress damage. Biological methods for synthesizing selenium nanoparticles (bio-Se-NPs) from bacteria are safe, inexpensive, and accessible. Therefore, we synthesized selenium nanoparticles using Lactobacillus plantarum (probiotic) to study the growth, immune, antioxidant, and inflammatory responses of selenium-rich Lactobacillus plantarum (SL, a type of bio-Se-NPs) fed Cyprinus carpio under low-salinity (5 g/L salinity) and high-salinity (10 g/L salinity) stresses. Analyses revealed that the addition of SL at a concentration of 1 mg/kg significantly alleviated the growth inhibition caused by high-salinity stress. SL significantly alleviated salinity-induced liver tissue injury (numerous cytoplasmic vacuolations the accumulation, inflammatory cell infiltration, nuclear lysis, and some blood congestion). SL significantly alleviated the abnormal levels of serum ALT, AST, GGT and LDH caused by salinity stress, and improved lipid metabolism (TG, TC, LDL-C, HDL-C). SL can also regulates cytokines and antioxidant genes (TNF-α, iL-1β, iL-10, TGFβ-1, SOD, CAT, GPx1, and HO-1) through the NF-κB and Nrf-2 signaling pathways and thereby reduce the inflammatory response and increase the antioxidant level, and these effects attenuate salinity-mediated oxidative damage. In conclusion, our findings indicate that SL can significantly promote the growth and development of fish and alleviate the adverse effects of high-salinity stress and thus, SL can be a potential feed additive for alleviating oxidative stress and inflammatory responses.

Metagenomic analysis of intestinal microbial function and key genes responsive to acute high-salinity stress in Nile tilapia (Oreochromis niloticus)

The intestinal microbiota is increasingly recognized as playing an important role in aquatic animals. To investigate the functional roles and mechanisms of the intestinal microbial genes/enzymes responding to salinity stress or osmotic pressure in fish, metagenomic analysis was carried out to evaluate the response of intestinal microbiota and especially their functional genes/enzymes from freshwater (the control group) to acute high salinity stress (the treatment group) in Nile tilapia. Our results showed that at the microbial community level, the intestinal microbiota in Nile tilapia generally underwent significant changes in diversity after acute high salinity stress. Among them, the shift in the bacterial community (mainly from Actinobacteria to Proteobacteria) dominated and had a large impact, the fungal community showed a very limited response, and other microbiota, such as phages, likely had a negligible response. At the functional level, the intestinal bacteriadecreased the normal physiological demand and processes, such as those of the digestive system and nervous system, but enhanced energy metabolism. Furthermore, at the gene level, some gene biomarkers, such as glutathione S-transferase, myo-inositol-1(or 4)-monophosphatase, glycine betaine/proline transport system permease protein, and some families of carbohydrate-active enzymes (GT4, GT2), were significantly enriched. However, GH15, GH23 and so on were significantly reduced. Exploring the functional details of the intestinal microbial genes/enzymes that respond to salinity stress in Nile tilapia sheds light on the mechanism of action of the intestinal microbiota with respect to the salinity adaptation of fish.

NADK-mediated proline synthesis enhances high-salinity tolerance in the razor clam

Euryhaline organisms can accumulate organic osmolytes to maintain osmotic balance between their internal and external environments. Proline is a pivotal organic small molecule and plays an important role in osmoregulation that enables marine shellfish to tolerate high-salinity conditions. During high-salinity challenge, NAD kinase (NADK) is involved in de novo synthesis of NADP(H) in living organisms, which serves as a reducing agent for the biosynthetic reactions. However, the role of shellfish NADK in proline biosynthesis remains elusive. In this study, we show the modulation of NADK on proline synthesis in the razor clam (Sinonovacula constricta) in response to osmotic stress. Under acute hypersaline conditions, gill tissues exhibited a significant increase in the expression of ScNADK. To elucidate the role of ScNADK in proline biosynthesis, we performed dsRNA interference in the expression of ScNADK in gill tissues to assess proline content and the expression levels of key enzyme genes involved in proline biosynthesis. The results indicate that the knock-down of ScNADK led to a significant decrease in proline content (P<0.01), as well as the expression levels of two proline synthetase genes P5CS and P5CR involved in the glutamate pathway. Razor clams preferred to use ornithine as substrate for proline synthesis when the glutamate pathway is blocked. Exogenous administration of proline greatly improved cell viability and mitigated cell apoptosis in gills. In conclusion, our results demonstrate the important role of ScNADK in augmenting proline production under high-salinity stress, by which the razor clam is able to accommodate salinity variations in the ecological niche.

Systematic assessment of salt tolerance based on morpho-physiological traits and genes related in inbred rice lines at the seedling stage

Abstract. Herawati R, Simarmata M, Masdar, Purwoko BS, Miswati. 2023. Systematic assessment of salt tolerance based on morpho-physiological traits and genes related in inbred rice lines at the seedling stage. Biodiversitas 24: 6256-6267. Salinity stress is an abiotic constraint that limits rice productivity. Salinity-tolerant traits are very complex and involve many genes. Therefore, it is difficult to conclude how rice plants respond to salinity stress. This study aimed to investigate the genetic potential of 19 rice genotypes for salt tolerance as well as the quantitative impacts of varying salinity stress levels on a subset of the genotypes. Salinity tolerance is identified in two stages: assessing salinity stress in nutrient solutions using 0, 5,000 (EC 7.8 dS.m-1), and 10,000 ppm (EC 15.62 dS.m-1). Gene expression analysis detected genes controlling salinity stress tolerance using two pairs of specific primers: DST (Drought Salt Tolerance) and OsAPX (ascorbate peroxidase). The results showed that all lines could survive high salinity stress up to EC 7.8 dS.m-1. Biplot is reflected in K-means grouping the 21 rice genotypes into three major groups, namely salt-sensitive (1 genotype, 4.75%), moderately salt-tolerant (2 genotypes, 9.5%), and salt-tolerant-very tolerant (18 genotypes, 85.7%). The DST and OsAPX1 genes showed both genes were expressed under salinity stress, although some lines showed smears or even did not appear at all, namely in G3 and G7. This result is consistent with the PCA analysis, where genotypes G3 and G7 are categorized as moderately tolerant. This study reveals that screening at the seedling stage combined with marker-assisted selection can identify tolerant genotypes. Furthermore, conducting field trials on soil salinity with EC &gt; 4 dS.m-1 is recommended to obtain salinity-tolerant lines as potential new varieties.

Motility behavior and physiological response mechanisms of aerobic denitrifier, Enterobacter cloacae strain HNR under high salt stress: Insights from individual cells to populations

The motility behaviors at the individual-cell level and the collective physiological responsive behaviors of aerobic denitrifier, Enterobacter cloacae strain HNR under high salt stress were investigated. The results revealed that as salinity increased, electron transport activity and adenosine triphosphate content decreased from 15.75 μg O2/g/min and 593.51 mM/L to 3.27 μg O2/g/min and 5.34 mM/L, respectively, at 40 g/L, leading to a reduction in the rotation velocity and vibration amplitude of strain HNR. High salinity stress (40 g/L) down-regulated genes involved in ABC transporters (amino acids, sugars, metal ions, and inorganic ions) and activated the biofilm-related motility regulation mechanism in strain HNR, resulting in a further decrease in flagellar motility capacity and an increase in extracellular polymeric substances secretion (4.08 mg/g cell of PS and 40.03 mg/g cell of PN at 40 g/L). These responses facilitated biofilm formation and proved effective in countering elevated salt stress in strain HNR. Moreover, the genetic diversity associated with biofilm-related motility regulation in strain HNR enhanced the adaptability and stability of the strain HNR populations to salinity stress. This study enables a deeper understanding of the response mechanism of aerobic denitrifiers to high salt stress.

Structure, ultrastructure and cation accumulation in quinoa epidermal bladder cell complex under high saline stress.

Quinoa is a facultative halophyte with excellent tolerance to salinity. In this study, the epidermal bladder cell complex (EBCc) of quinoa leaves was studied to determine their cellular characteristics and involvement in salt tolerance. We used light microscopy, confocal RAMAN microscopy, confocal fluorescence microscopy, transmission electron microscopy, and environmental scanning electron microscopy complemented by energy dispersive X-ray analysis. Ionic content was quantified with flame atomic absorption spectroscopy and with flame emission photometry. Results show that: (i) the number of EBCcs remains constant but their density and area vary with leaf age; (ii) stalk cells store lipids and exhibit thick walls, bladder cells present carotenes in small vesicles, oxalate crystals in vacuoles and lignin in their walls and both stalk and bladder cells have cuticles that differ in wax and cutin content; (iii) chloroplasts containing starch can be found on both stalk and bladder cells, and the latter also presents grana; (iv) plasmodesmata are observed between the stalk cell and the bladder cell, and between the epidermal cell and thestalkcell, and ectodesmata-like structures are observed on the bladder cell. Under high salinity conditions, (v) there is a clear tendency to accumulate greater amounts of K+ with respect to Na+ in the bladder cell; (vi) stalk cells accumulate similar amounts of K+ and Na+; (vii) Na+ accumulates mainly in the medullary parenchyma of the stem. These results add knowledge about the structure, content, and role of EBCc under salt stress, and surprisingly present the parenchyma of the stem as the main area of Na+ accumulation.

Mining the microbiome of Lake Afdera to gain insights into microbial diversity and biosynthetic potential.

Microorganisms inhabiting hypersaline environments have received significant attention due to their ability to thrive under poly-extreme conditions, including high salinity, elevated temperatures and heavy metal stress. They are believed to possess biosynthetic gene clusters (BGCs) that encode secondary metabolites as survival strategy and offer potential biotechnological applications. In this study, we mined BGCs in shotgun metagenomic sequences generated from Lake Afdera, a hypersaline lake in the Afar Depression, Ethiopia. The microbiome of Lake Afdera is predominantly bacterial, with Acinetobacter (18.6%) and Pseudomonas (11.8%) being ubiquitously detected. A total of 94 distinct BGCs were identified in the metagenomic data. These BGCs are found to encode secondary metabolites with two main categories of functions: (i) potential pharmaceutical applications (nonribosomal peptide synthase NRPs, polyketide synthase, others) and (ii) miscellaneous roles conferring adaptation to extreme environment (bacteriocins, ectoine, others). Notably, NRPs (20.6%) and bacteriocins (10.6%) were the most abundant. Furthermore, our metagenomic analysis predicted gene clusters that enable microbes to defend against a wide range of toxic metals, oxidative stress and osmotic stress. These findings suggest that Lake Afdera is a rich biological reservoir, with the predicted BGCs playing critical role in the survival and adaptation of extremophiles.

Genome-wide identification of the GRF family in sweet orange (Citrus sinensis) and functional analysis of the CsGRF04 in response to multiple abiotic stresses

BackgroundCitrus is one of the most valuable fruits worldwide and an economic pillar industry in southern China. Nevertheless, it frequently suffers from undesirable environmental stresses during the growth cycle, which severely restricts the growth, development and yield of citrus. In plants, the growth-regulating factor (GRF) family of transcription factors (TF) is extensively distributed and plays an vital part in plant growth and development, hormone response, as well as stress adaptation. However, the systematic identification and functional analysis of GRF TFs in citrus have not been reported.ResultsHere, a genome-wide identification of GRF TFs was performed in Citrus sinensis, 9 members of CsGRFs were systematically identified and discovered to be scattered throughout 5 chromosomes. Subsequently, physical and chemical properties, phylogenetic relationships, structural characteristics, gene duplication events, collinearity and cis-elements of promoter were elaborately analyzed. In particular, the expression patterns of the CsGRF genes in response to multiple phytohormone and abiotic stress treatments were investigated. Predicated on this result, CsGRF04, which exhibited the most differential expression pattern under multiple phytohormone and abiotic stress treatments was screened out. Virus-induced gene silencing (VIGS) technology was utilized to obtain gene silenced plants for CsGRF04 successfully. After the three stress treatments of high salinity, low temperature and drought, the CsGRF04-VIGS lines showed significantly reduced resistance to high salinity and low temperature stresses, but extremely increased resistance to drought stress.ConclusionsTaken together, our findings systematically analyzed the genomic characterization of GRF family in Citrus sinensis, and excavated a CsGRF04 with potential functions under multiple abiotic stresses. Our study lay a foundation for further study on the function of CsGRFs in abiotic stress and hormone signaling response.

The specialized parenchyma in the Paspalum vaginatum stem as a strategy to water deficit and salinity

Abstract Paspalum vaginatumis a halophyte plant found along coastal plains, which presents cells with atypically thickened walls in the ground tissue of the stem stele (GTS). The tolerance of this species to high salinity and water stress led us to investigate whether the thickened walls could be related to adaptation to the coastal environment. Thus, we sought to characterize the cell walls that make up the GTS ofP. vaginatum, describe the tissue, and verify the influence of the water resource on the thickening of the walls and a possible function related to the reserve of substances. For this, analyses were carried out using light microscopy, transmission electronic microscopy, and histochemical tests. The samples were collected in the field during low and high rainfall periods.Paspalum vaginatumGTS cells have pectic-cellulosic primary walls. In most basal internodes, these cells presented thickened walls formed in two to three layers. Statistical analysis demonstrated that the level of precipitation is directly related to cell wall thickening. The data suggest the storage and mobilization of substances through the cell wall of the specialized parenchyma.

Pharmacological Activities of Sonneratia Alba Mangrove Plant : A Review

Indonesia is a country with a high amount of diverse natural resources. Various plants have important roles in supporting human medicinal needs due to their availability in providing various medicinal resources. One of the natural resources is Sonneratia alba, a species of mangrove plant known with high adaptive ability and tolerance to extreme environmental conditions such as high saline stress, light intensity exposure, and free radicals. This review summarized the findings on pharmacological activities of S. alba. Several studies reported the adaptive ability of S. alba with its various pharmacological activities such as antimalarial, antioxidant, antimicrobial, and anticancer. These activities are strongly correlated with its bioactive constituents such as terpenoid, alkaloid, tannin, quinone, phenolic, and flavonoid. The mechanism of each pharmacological activity has been suggested in several studies. These findings could be beneficial in drug discovery for several infectious and degenerative diseases and in the development of drugs at industrial stage. Keyword: Anticancer, antimalaria, antimicrobial, antioxidant, Sonneratia alba Â

RETRACTED: Enhanced biofiltration coupled with ultrafiltration process in marine recirculating aquaculture system: Fast start-up of nitrification and long-term performance

In marine recirculating aquaculture systems (RAS), the biological nitrification system usually suffers from long time start-up and proliferation of potential pathogenic bacteria under the high salinity stress. This study aims to develop a strategy for fast start- up and long-term biosecurity of marine RAS by using a combined biofiltration system (ceramic rings (CR) - granular activated carbon (GAC) - ultrafiltration (UF) process) in an actual marine RAS for selenotoca multifasciata. The ammonia nitrogen and dissolved organic matter (DOM) removal performance, membrane fouling characteristics and microbial communities during long-term operation (200 days) were investigated. The CR-GAC-UF process minimized the start-up time of the nitrification system to 14 days under low ammonia concentrations (below 2 mg/L). Long-term operation of the marine RAS with ammonia and nitrite nitrogen stabilized below 0.1 mg/L with a daily ammonia nitrogen removal rate of 91.7 %. The UF membranes were operated at fluxes at 15 LHM and the protein/polysaccharide ratios of soluble microbial products (SMP) and extracellular polymeric substances (EPS) on the membranes were stable below 0.5 with low fouling levels. A number of bacterial genera that have the potential to degrade protein and humic-like substances were recognized, which was related to the long-term DOM removal. Candidatus_Nitrosopumilus, Nitrosomonas_sp. and Nitrospira sp. ENR4 were detected as the core nitrifiers in CR-GAC-UF process, which were closely related to the amoABC, hao and nxrA genes (p < 0.05). With the multi-stage barrier of CR-GAC-UF, the heterotrophic plate count in therecirculating water was kept at 3 ± 1 CFU/mL and the relative abundance of potential pathogens declined gradually below 0.81 %. Taken together, this study provides a theoretical basis for the wider application of marine RAS.

Adaptive characteristics of indigenous microflora in an organically contaminated high salinity groundwater

Salinity, a critical factor, could directly or indirectly affect the microbial community structure and diversity. Changes in salinity levels act as environmental filters that influence the transformation of key microbial species. This study investigates the adaptive characteristics of indigenous microflora in groundwater in relation to external organic pollutants under high salinity stress. A highly mineralized shallow groundwater in Northwest China was conducted as the study area, and six representative sampling points were chosen to explore the response of groundwater hydrochemical parameters and microflora, as well as to identify the tolerance mechanisms of indigenous microflora to combined pollution. The results revealed that the dominant genera found in high salinity groundwater contaminated with organic pollutants possess the remarkable ability to degrade such pollutants even under challenging high salinity conditions, including Halomonas, Pseudomonas, Halothiobacillus, Sphingomonas, Lutibacter, Aquabacterium, Thiomicrospira, Aequorivita, etc. The hydrochemical factors, including total dissolved solids (TDS), sulfide, nitrite, nitrate, oxidation reduction potential (ORP), NH3–N, Na, Fe, benzene series, phenols, and halogenated hydrocarbons, demonstrated a significant influence on microflora. High levels of sulphate and sulfide in groundwater can exhibit dual effects on microflora. On one hand, these compounds can inhibit the growth and metabolism of microorganisms. On the other hand, they can also serve as effective electron donors/receptors during the microbial degradation of organic pollutants. Microorganisms exhibit resilience to the inhibitory effects of high salinity and organic pollutants via a series of tolerance mechanisms, such as strengthening the extracellular membrane barrier, enhancing the synthesis of relevant enzymes, initiating novel biochemical reactions, improving cellular self-healing capabilities, responding to unfavorable environmental conditions by migration, and enhancing the S cycle for the microbial metabolism of organic pollutants.

Elevated atmospheric CO2 concentration mitigates salt damages to safflower: Evidence from physiological and biochemical examinations

The physiological and biochemical responses of salt-stressed safflower to elevated CO2 remain inadequately known. This study investigated the interactive effects of high CO2 concentration (700 ± 50 vs. 400 ± 50 μmol mol−1) and salinity stress levels (0.4, 6, and 12 dS m−1, NaCl) on growth and physiological properties of four safflower (Carthamus tinctorius L.) genotypes, under open chamber conditions. Results showed that the effects of CO2 on biomass of shoot and grains depend on salt stress and plant genotype. Elevated CO2 conditions increased shoot dry weight under moderate salinity stress and decreased it under severe stress. The increased CO2 concentration also increased the safflower genotypes' relative water content and their K+/Na + concentrations. Also enriched CO2 increased total carotenoid levels in safflower genotypes and improved membrane stability index by reducing H2O2 levels. In addition, increased CO2 level led to an increase in seed oil content, under both saline and non-saline conditions. This effect was particularly pronounced under severe saline conditions. Under conditions of high CO2 and salinity, the Koseh genotype exhibited higher grain weight and seed oil content than other genotypes. This advantage is due to the higher relative water content, maximum quantum efficiency of photosystem II (Fv/Fm), and K+/Na+, as well as the lower Na+ and H2O2 concentrations. Results indicate that the high CO2 level mitigated the destructive effect of salinity on safflower growth by reducing Na + uptake and increasing the Fv/Fm, total soluble carbohydrates, and membrane stability index. This finding can be used in safflower breeding programs to develop cultivars that can thrive in arid regions with changing climatic conditions.

Continuous In Vivo Monitoring of Indole-3-Acetic Acid and Salicylic Acid in Tomato Leaf Veins Based on an Electrochemical Microsensor.

Indole-3-acetic acid (IAA) and salicylic acid (SA), as critical plant hormones, are involved in multiple physiological regulatory processes of plants. Simultaneous and continuous in vivo detection of IAA and SA will help clarify the mechanisms of their regulation and crosstalk. First, this study reports the development and application of an electrochemical microsensor for simultaneous and continuous in vivo detection of IAA and SA. This electrochemical microsensor system consisted of a tip (length, 2 mm) of platinum wire (diameter, 0.1 mm) modified with carbon cement and multi-walled carbon nanotubes, an untreated tip (length, 2 mm) of platinum wire (diameter, 0.1 mm), as well as a tip (length, 2 mm) of Ag/AgCl wire (diameter, 0.1 mm). It was capable of detecting IAA in the level ranging from 0.1 to 30 µM and SA ranging from 0.1 to 50 µM based on the differential pulse voltammetry or amperometric i-t., respectively. The dynamics of IAA and SA levels in tomato leaf veins under high salinity stress were continuously detected in vivo, and very little damage occurred. Compared to conventional detection methods, the constructed microsensor is not only suitable for continuously detecting IAA and SA in microscopic plant tissue in vivo, it also reduces the damage done to plants during the detection. More importantly, the continuous and dynamic changes in IAA and SA data obtained in stiu through this system not only can help clarify the interaction mechanisms of IAA and SA in plants, it also helps to evaluate the health status of plants, which will promote the development of basic research in botany and precision agriculture.

Abiotic stress applied to Tetraselmis subcordiformis reveals enhanced metabolic responses and increased production of Omega-3 fatty acids: A Metabolomic approach

The appeal of high value algal metabolites is certain due to their sustainability, low energy and space requirements. Yet, commercial-level production of such products is limited and has the potential to be enhanced. In microalgae Tetraselmis subcordiformis (T. subcordiformis) was subjected to four different stressors and the stress response was recorded in terms of changes in the metabolic profile of the strain. The stressors applied were nitrogen (N-starvation) and phosphorus starvation (P-starvation), high salinity, and cold stress. Although growth of the strain was impacted by application of all stressors, an increase of 34 % and 14.9 % in the protein content was noted for 100 PSU and P-starvation stress. Moreover, nitrogen content increase by 20 % and 5.8 % for 100 PSU and N-starvation stress. While the most common lipids for algae in high salinity and N-starvation stressors were triglycerides with α-linoleic (18:3), linoleic (18:2), and palmitic (16:0) fatty acids. Overall, compared to all stressors applied high salinity of 100 PSU enhanced the overall metabolic profile of T. subcordiformis.

Effects of salinity on sulfur-dominated autotrophic denitrification microorganisms: Microbial community succession, key microorganisms and response mechanisms

This study investigated the performance of sulfur-dominated autotrophic denitrification (SAD) process under four different salinities of 0 %, 0.5 %, 3 %, and 6 %, simulating groundwater, sewage, seawater, and industrial wastewater scenarios, respectively. In terms of removal efficiency, the nitrate removal rates at 0.5 % and 3 % salinities decreased by 5.8 % and 16.8 %, respectively, compared to 0 % salinity. At 6 % salinity, the efficiency fluctuated during long-term operation, ranging from 56.0 % to 89.9 % of the value at 0 % salinity. According to the succession of microbial communities across time and salinity gradients, the dominant denitrification functional microorganisms were ranked by their salinity-tolerance ability as low-tolerant bacteria (0 %–0.5 %: Simplicispira, Herpetosipin, and Thermomonas), medium-tolerant bacteria (0 %–3 %: Thiobacillus and Sulfurimonas), high-tolerant bacteria (3 %–6 %: Thiogranum, Xanthomarina, and Vicingus), and halophilic bacteria (6 %: Aequorivita). Additionally, Aequorivita and Thiogranum, as the top 2 genera under 6 % salinity, presented positive and negative correlations with nitrate removal efficiency. The molecular ecological network revealed that increased positive interactions of 58.7 % among dominant genera occurred at 6 % salinity, confirming an effective cooperation coping with the high-salinity stress. In addition, the microbial responses to high-salinity primarily exhibited 22 %–45 % decrease in protein content, a 15 % decrease in live cells proportion, and a comparable level of individual functional gene expression. The results indicate that the efficiency of SAD by high salinity is determined by biomass amount and individual microbial capacity. This study offered new sights for understanding microbial succession and relationships in response to saltwater with diverse origins and varying water qualities in SAD systems.

Function of taurine and its synthesis-related genes in hypertonic regulation of Sinonovacula constricta

Salinity changes affect the osmotic gradient across the gill epithelium of marine species. Taurine is an important osmoregulator with a crucial role in osmoregulation in marine bivalves. This study determined the osmolality, taurine content, key enzymes involved in taurine synthesis (cysteine dioxygenase (CDO), cysteine sulfinic acid decarboxylase (CSAD), and taurine transporter (TauT)) and related gene expression in razor clam Sinonovacula constricta in response to high salt stress [high salt seawater (S30) versus high salt seawater with taurine supplementation (S30T) versus natural salinity control]. The data were recorded at 0, 6, 12, 24, 48, 72 h. Serum osmolality significantly increased under high salt conditions compared with the control group (P < 0.05). When serum osmolality had stabilized (after 48 h), there was no significant difference in serum osmolality between the S30T and control groups (P > 0.05), but serum osmolality was significantly lower in the S30 versus control group (P < 0.05). Taurine content significantly increased under high salt stress and remained high (P < 0.05). CSAD and CDO content was higher in S30 than in S30T, whereas TauT was significantly lower in S30 than in the control group eventually (P < 0.05). Expression of CDO and CSAD in the S30 and S30T groups was significantly higher than in control animals (P < 0.05), with that in S30 being higher than in S30T. By contrast, TauT expression peaked 6 h after stress in S30 and S30T, but was lower in S30 than in the control group (P < 0.05). These results demonstrate that S. constricta is an osmoconformer, with exogenous taurine relieving the stress of osmoregulation caused by insufficient endogenous taurine in cells. These findings further enhance our understanding of the regulatory mechanisms underlying the response of S. constricta to high salinity stress.

Genetic parameters of various local corn cultivars in high salinity stress

Future demand for maize will not be easily met due to climate change and its development using marginal soils that are stressed by salinity. This study aims to identify the genetic parameters of corn plants under high salinity stress. The research was arranged in a randomized completely block design (RCBD) consisting of six local maize cultivars, namely Gento, Lanca, Pulut, Lokal, Lei, and Sigi Merah. Each treatment was repeated four times. The results showed that two traits had a high coefficient of genotypic diversity, four traits had a high coefficient of phenotypic diversity and six traits had high heritability and genetic progress. Plant height, the greenness of the leaves, age of male flower release, age of blooming female flowers, the position of the ear, harvest age, length of cob without stalks, and diameter of the cob were positively and significantly correlated with yield. Plant height and cob height can be used as criteria for increasing maize yields through indirect selection. In future studies suggest that various local maize cultivars can be applied to situations of high salinity stress.

Exogenous strigolactones enhance salinity tolerance in cotton (Gossypium hirsutum L.) seedlings

All around the world, salt stress has severely restricted plant development. Cotton is one of the most important cash crops, but the saline soil negatively influences the quality and output of plants. Strigolactones (SLs) is a new type of phytohormone that plays an important role in the development of plants. However, the underlying mechanism of how SLs alleviate the high salinity stress is unclear in cotton. In this research, we observed that exogenous 10 μΜ GR24 (a synthetic analog of SLs) significantly alleviated the salt stress (200 mM NaCl) in the hydroponically planted seedlings. Under salt stress, the contents of proline, O2− malondialdehyde, and hydrogen peroxide were greatly decreased by 48.40%, 45.57%, 31.03%, and 35.52%. Combined with transcriptome analysis and corresponding verification, it was figured out that with the application of exogenous GR24, the genes encoding antioxidant enzymes, chlorophyll biosynthesis, and photosynthesis system were significantly up-regulated, while the activities of antioxidant enzymes, the content of chlorophyll, and the efficiency of photosynthesis were also significantly improved under salt stress in cotton seedlings. Thus, the exogenous application of SLs could enhance the salt tolerance of cotton seedlings, which displayed its great potential for cotton production in salinized land.