Salt Stress Environment Research Articles

The overlooked salt: Impact of dark septate endophytes on alfalfa at varying sodium sulfate levels

Sodium sulfate (Na2SO4) is one sodium salt extensively found in saline soils; in certain regions, it is the dominant salt present. Dark septate endophytes (DSE) are competent in enhancing plants’ resistance to stressed environments. Nevertheless, little is known about the role of DSE in enhancing plant tolerance to Na2SO4. This study examined DSE growth and its impacts on alfalfa plants exposed to varying Na2SO4 concentrations (0%, 0.15%, 0.3%, and 0.45% (w/w)). Our findings revealed that DSE can thrive even in salt-stress environments. On the 8th day of cultivation, their biomass reached the highest level under 0.45% salt concentration. Moreover, DSE successfully colonized alfalfa roots and significantly enhanced plant growth and development across the various salt gradients. Notably, DSE made the highest contribution 68% to the total biomass of alfalfa at 0.45% salt concentration. Meanwhile, DSE significantly decreased the presence of root’s Na+ across varying salt gradients. Additionally, DSE significantly increased catalase (CAT) activity at salt concentrations of 0.3% and 0.45%. Our study also revealed strong positive correlations of plant biomass with the root index, root’s K+ content, and K+/Na+ ratio, and strong negative correlations of plant biomass with root’s Na+ content and soil’s Na+ and SO42− contents. Structural equation modeling (SEM) demonstrated that DSE indirectly enhanced plant’s shoot biomass under various salt stresses via increasing root length, decreasing root’s Na+ content, and raising CAT activity, while salt indirectly reduced plant’s shoot weight via reducing root length or increasing root’s Na+ content or exerted a direct negative effect on plant shoot biomass. Thus, DSE are instrumental in bolstering the salt tolerance of plants, which holds strategic importance for the management of saline-alkali soils.

γ-Aminobutyric Acid Alleviates Salinity-Induced Impairments in Rice Plants by Improving Photosynthesis and Upregulating Osmoprotectants and Antioxidants

Salt stress is a significant abiotic stress that hinders the growth of rice (Oryza sativa L.) and reduces their yield. Previous research has examined the synthesis of γ-aminobutyric acid (GABA) and its role in plant resistance under various abiotic stresses. However, the synthesis of GABA and its ability to mitigate damage caused by salt stress—particularly its effects on osmotic adjustment, antioxidant defense, photosynthesis, and overall plant growth throughout the entire rice lifecycle—remains unclear. Therefore, we conducted two experiments using salt-tolerant rice cultivar Lianjian 5 (J-5) and salt-susceptible cultivar Lianjing 7 (L-7). In Experiment I, RNA-seq (RNA sequencing) was used to analyze the differential expression of the transcriptome between CK and salinity treatments, revealing the key roles of GABA in salt tolerance. In Experiment II, different levels of exogenous GABA were applied to salt-stressed plants to investigate its physiological role in enhancing salt tolerance. Therefore, RNA-seq (RNA sequencing) was used to analyze the differential expression of the transcriptome between CK and salinity treatments, revealing the key roles of GABA in salt tolerance. Subsequently, different levels of exogenous GABA were applied to salt-stressed plants to investigate its physiological role in enhancing salt tolerance. We measured the activities of superoxide dismutase, peroxidase, and catalase, as well as photosynthetic characteristics such as photosynthesis, transpiration, chlorophyll content, stomatal density and size, and leaf anatomical features. The RNA-seq analysis revealed that GABA production is enhanced via the glutamate decarboxylase (GAD) gene (LOC4333932) in the salt-resistant rice cultivar. Exogenous GABA application improves salt-stress tolerance by increasing endogenous ABA and GABA contents, which enhance osmotic adjustment, boost antioxidant defenses, and regulate ion balance. These combined effects help maintain photosynthetic efficiency and support overall plant growth under salt-stressed environments. Additionally, the increased proportion of mesophyll cell periphery covered by chloroplasts (Sc/Sm) indicated enhanced mesophyll conductance. These helped maintain photosynthesis under saline conditions while reducing water consumption.

YOLOv8-licorice: a lightweight salt-resistance detection method for licorice based on seed germination state.

Seeds will display different germination states during the germination process, and their good or bad state directly influences the subsequent growth and yield of the crop. This study aimed to address the difficulties of obtaining the images of seed germination process in all time series and studying the dynamic evolution law of seed germination state under stress conditions. A licorice sprouting experiment was performed using a seed sprouting phenotype acquisition system to obtain images of the sprouting process of licorice in full-time sequence. A labeled dataset of licorice full-time sequence sprouting process images was constructed based on the four states of unsprouted, sprouted, cracked, and shelled in the sprouting process. An optimized model, YOLOv8-Licorice, was developed based on the YOLOv8-n model and its effectiveness was demonstrated by comparative and ablation tests. Different salt stress environments were simulated via NaCl aqueous solution concentration, and germination experiments of licorice seeds were performed under different salt stresses. The germination state of licorice under different salt stress environments was detected using the YOLOv8-Licorice detection model. Percentage curve of licorice seeds in an unsprouted state displayed a continuous decreasing trend. For the percentage curve of licorice seeds in the sprouted state, an increasing and then decreasing trend was observed under the condition of 0-200 mmol/L NaCl solution, and a continuous increasing trend was observed under the condition of 240-300 mmol/L NaCl solution. Licorice seeds in the cracked state demonstrated percentage curves with an increasing and then decreasing trend under the condition of 0-140 mmol/L NaCl solution and a continuous increasing trend under the condition of 160-300 mmol/L NaCl solution. The percentage curve of licorice seeds in shelled state displayed a continuous increasing trend in 0-200 mmol/L NaCl solution condition and remained horizontal in 220-300 mmol/L NaCl solution condition. Overall, this study provides a valuable method involving the seed sprouting phenotype acquisition system and the proposed method for detecting the germination state of licorice seeds. This method serves as a valuable reference to comprehensively understand the seed sprouting process under triggering treatment.

Evaluation of cucumber seed germination vigor under salt stress environment based on improved YOLOv8.

Seed germination vigor is one of the important indexes reflecting the quality of seeds, and the level of its germination vigor directly affects the crop yield. The traditional manual determination of seed germination vigor is inefficient, subjective, prone to damage the seed structure, cumbersome and with large errors. We carried out a cucumber seed germination experiment under salt stress based on the seed germination phenotype acquisition platform. We obtained image data of cucumber seed germination under salt stress conditions. On the basis of the YOLOv8-n model, the original loss function CIoU_Loss was replaced by ECIOU_Loss, and the Coordinate Attention(CA) mechanism was added to the head network, which helped the model locate and identify the target. The small-target detection head was added, which enhanced the detection accuracy of the tiny target. The precision P, recall R, and mAP of detection of the model improved from the original values of 91.6%, 85.4%, and 91.8% to 96.9%, 97.3%, and 98.9%, respectively. Based on the improved YOLOv8-ECS model, cucumber seeds under different concentrations of salt stress were detected by target detection, cucumber seed germination rate, germination index and other parameters were calculated, the root length of cucumber seeds during germination was extracted and analyzed, and the change characteristics of root length during cucumber seed germination were obtained, and finally the germination activity of cucumber seeds under different concentrations of salt stress was evaluated. This work provides a simple and efficient method for the selection and breeding of salt-tolerant varieties of cucumber.

Coating seeds with purified-hydrocolloids extracted from conventional activated sludge affects the growth physiology of wheat under gradient salt stress

With continuous innovations in wastewater treatment technology, the use of excess sludge has become a research focus. Purified-hydrocolloids obtained from aerobic granular sludge (AGS) and conventional activated sludge (CAS) have many practical applications, including waterproofing, adsorption, flame retardance, slow-release properties, and seed coating. In this study, purified-hydrocolloids extracted from CAS was used as a new seed coating, which was uniformly sprayed onto the surface of wheat seeds. Purified-hydrocolloids was most effective in resisting salt stress in wheat seedlings at a NaCl concentration of 125 mmol/L (soil salinity 2.74 g/Kg). The germination percentage, plant height, K+/Na+ ratio, soluble sugar and soluble protein contents of purified-hydrocolloids-coated seeds increased by 13.33 %, 46.32 %, 37.25 %, 8.89 %, and 36.22 %, respectively, compared with wheat seeds without purified-hydrocolloids coating. Inhibition of O2− production activity and malondialdehyde content was reduced by 38.62 % and 48.00 %, respectively. Therefore, the purified-hydrocolloids coating had a mitigating effect on wheat seed germination and seedling growth in salt-stressed environments, and this application would be beneficial to the use of saline soil resources and the improvement of ecosystems in coastal areas.

Transcriptome Analysis Reveals the Important Role of Vitamin B12 in the Response of Natronorubrum daqingense to Salt Stress.

Natronorubrum daqingense JX313T is an extremely halophilic archaea that can grow in a NaCl-saturated environment. The excellent salt tolerance of N. daqingense makes it a high-potential candidate for researching the salt stress mechanisms of halophilic microorganisms from Natronorubrum. In this study, transcriptome analysis revealed that three genes related to the biosynthesis of vitamin B12 were upregulated in response to salt stress. For the wild-type (WT) strain JX313T, the low-salt adaptive mutant LND5, and the vitamin B12 synthesis-deficient strain ΔcobC, the exogenous addition of 10 mg/L of vitamin B12 could maximize their cell survival and biomass in both optimal and salt stress environments. Knockout of cobC resulted in changes in the growth boundary of the strain, as well as a significant decrease in cell survival and biomass, and the inability to synthesize vitamin B12. According to the HPLC analysis, when the external NaCl concentration (w/v) increased from 17.5% (optimal) to 22.5% (5% salt stress), the intracellular accumulation of vitamin B12 in WT increased significantly from (11.54 ± 0.44) mg/L to (15.23 ± 0.20) mg/L. In summary, N. daqingense is capable of absorbing or synthesizing vitamin B12 in response to salt stress, suggesting that vitamin B12 serves as a specific compatible solute effector for N. daqingense during salt stress.

Overexpression of E3 ligase RING finger protein BrRING509 enhances salt stress tolerance in transgenic Arabidopsis plants

Salinity is an important abiotic stress that has an impact on crop yields and quality. Ubiquitin-mediated protein degradation enables plants to effectively withstand environmental stresses. The E3 ligases have been identified as a crucial component of the ubiquitination pathway, which regulates plant responses to abiotic stresses. The RING finger E3 ligase family of proteins has a critical role in plant growth and response to many abiotic stresses. In this study, we identified an important salt-responsive gene, BrRING509 in Brassica rapa. It is localized throughout the plasma membrane and nucleus. The functional results suggest that BrRING509 significantly increases salt stress tolerance in Arabidopsis (Arabidopsis thaliana) transgenic plants. Overexpression of BrRING509 could increase the survival and root length of transgenic seedlings under different salt concentrations. Additionally, ectopic expression of BrRING509 significantly increases the expression level of salt-responsive genes, including AtRD22 and AtRD29A in Arabidopsis transgenic plants subjected to salt stress treatments. The findings of this study indicate that BrRING509 plays a positive role in salt stress tolerance and might be an important candidate gene for the adaptation of Brassica plants in salt-stress environments.

Mycorrhizas Affect Physiological Performance, Antioxidant System, Photosynthesis, Endogenous Hormones, and Water Content in Cotton under Salt Stress.

Saline-alkali stress seriously endangers the normal growth of cotton (Gossypium hirsutum). Arbuscular mycorrhizal fungi (AMF) could enhance salt tolerance by establishing symbiotic relationships with plants. Based on it, a pot experiment was conducted to simulate a salt environment in which cotton was inoculated with Paraglomus occultum to explore its effects on the saline-alkali tolerance of cotton. Our results showed that salt stress noticeably decreased cotton seedling growth parameters (such as plant height, number of leaves, dry weight, root system architecture, etc.), while AMF exhibited a remarkable effect on promoting growth. It was noteworthy that AMF significantly mitigated the inhibitory effect of salt on cotton seedlings. However, AMF colonization in root and soil hyphal length were collectively descended via salt stress. With regard to osmotic regulating substances, Pro and MDA values in roots were significantly increased when seedlings were exposed to salt stress, while AMF only partially mitigated these reactions. Salt stress increased ROS levels in the roots of cotton seedlings and enhanced antioxidant enzyme activity (SOD, POD, and CAT), while AMF mitigated the increases in ROS levels but further strengthened antioxidant enzyme activity. AMF inoculation increased the photosynthesis parameters of cotton seedling leaves to varying degrees, while salt stress decreased them dramatically. When inoculated with AMF under a salt stress environment, only partial mitigation of these photosynthesis values was observed. Under saline-alkali stress, AMF improved the leaf fluorescence parameters (φPSII, Fv'/Fm', and qP) of cotton seedlings, leaf chlorophyll levels, and root endogenous hormones (IAA and BR); promoted the absorption of water; and maintained nitrogen balance, thus alleviating the damage from salt stress on the growth of cotton plants to some extent. In summary, mycorrhizal cotton seedlings may exhibit mechanisms involving root system architecture, the antioxidant system, photosynthesis, leaf fluorescence, endogenous hormones, water content, and nitrogen balance that increase their resistance to saline-alkali environments. This study provide a theoretical basis for further exploring the application of AMF to enhance the salt tolerance of cotton.

The Genetic Architecture of the Root System during Seedling Emergence in Populus euphratica under Salt Stress and Control Environments

The growth of the Populus euphratica root system is of great significance for its survival under adverse environmental stress. In harsh saline-stress environments, the proportion, morphology, and functionality of the taproots and lateral roots and how they manifest specific adaptive structures, growth strategies, and potential genetic controls are still subjects for further exploration. In this study, we delve into the fundamental patterns and trade-offs of root morphology and functionality by constructing an environment-induced differential interaction equation (EDIE) to model the independent and interactive growth of the root system while considering the influence of environmental conditions. We identify 93 key QTLs in the control group and 44 key QTLs in the salt-stress group, of which 2 QTLs are significant in both environments. By constructing ODE-based QTL networks, we explore in depth how these loci regulate the growth of the root system under different environmental conditions while considering their independent direct effects and epistatic effects among loci. This study elucidates the intrinsic factors that influence the variations in taproots and lateral roots, providing crucial insights into the relationship between root morphology and functionality.

Biochar derived from olive oil pomace mitigates salt stress on seedling growth of forage pea.

Studies are being conducted to develop strategies to reduce the adverse effects of salinity stress. In the present study, it was aimed to determine the interactive effects of salinity stress with biochar on plant growth-the physiological and biochemical attributes of forage peas (Pisum sativum ssp. arvense L.). Salt applications were carried out with irrigation water at concentrations of 0, 25, 50, 75, and 100 mM NaCl. The experiment was conducted using a randomized complete block design with three applications [control: 0 (B0), 2.5% biochar (B1), and 5% biochar (B2)], five salt doses [0 (S0), 25 (S1), 50 (S2), 75 (S3), and 100 (S4) mM NaCl], and three replications, arranged in a 3 × 5 factorial arrangement. In the salt-stressed environment, the highest plant height (18.75 cm) and stem diameter (1.71 mm) in forage pea seedlings were obtained with the application of B1. The root fresh (0.59 g/plant) and dry weight (0.36 g/plant) were determined to be the highest in the B1 application, both in non-saline and saline environments. A decrease in plant chlorophyll content in forage pea plants was observed parallel to the increasing salt levels. Specifically, lower H2O2, MDA, and proline content were determined at all salt levels with biochar applications, while in the B0 application these values were recorded at the highest levels. Furthermore, in the study, it was observed that the CAT, POD, and SOD enzyme activities were at their lowest levels at all salt levels with the biochar application, while in the B0 application, these values were determined to be at the highest levels. There was a significant decrease in plant mineral content, excluding Cl and Na, parallel to the increasing salt levels. The findings of the study indicate that biochar amendment can enhance forage peas' growth by modulating the plant physiology and biochemistry under salt stress. Considering the plant growth parameters, no significant difference was detected between 2.5% and 5% biochar application. Therefore, application of 2.5 biochar may be recommended.

The Salinity Survival Strategy of Chenopodium quinoa: Investigating Microbial Community Shifts and Nitrogen Cycling in Saline Soils.

Quinoa is extensively cultivated for its nutritional value, and its exceptional capacity to endure elevated salt levels presents a promising resolution to the agricultural quandaries posed by salinity stress. However, limited research has been dedicated to elucidating the correlation between alterations in the salinity soil microbial community and nitrogen transformations. To scrutinize the underlying mechanisms behind quinoa's salt tolerance, we assessed the changes in microbial community structure and the abundance of nitrogen transformation genes across three distinct salinity thresholds (1 g·kg-1, 3 g·kg-1, and 6 g·kg-1) at two distinct time points (35 and 70 days). The results showed the positive effect of quinoa on the soil microbial community structure, including changes in key populations and its regulatory role in soil nitrogen cycling under salt stress. Choroflexi, Acidobacteriota, and Myxococcota were inhibited by increased salinity, while the relative abundance of Bacteroidota increased. Proteobacteria and Actinobacteria showed relatively stable abundances across time and salinity levels. Quinoa possesses the ability to synthesize or modify the composition of keystone species or promote the establishment of highly complex microbial networks (modularity index > 0.4) to cope with fluctuations in external salt stress environments. Furthermore, quinoa exhibited nitrogen (N) cycling by downregulating denitrification genes (nirS, nosZ), upregulating nitrification genes (Archaeal amoA (AOA), Bacterial amoA (AOB)), and stabilizing nitrogen fixation genes (nifH) to absorb nitrate-nitrogen (NO3-_N). This study paves the way for future research on regulating quinoa, promoting soil microbial communities, and nitrogen transformation in saline environments.

Promotional Properties of ACC Deaminase-Producing Bacterial Strain DY1-3 and Its Enhancement of Maize Resistance to Salt and Drought Stresses.

Salt stress and drought stress can decrease the growth and productivity of agricultural crops. Plant growth-promoting bacteria (PGPB) may protect and promote plant growth at abiotic stress. The aim of this study was to search for bacterial strains that can help crops resist rises in drought and salt stresses, to improve crop seed resistance under drought and salt stresses, and to investigate the effect of bacterial strains that can help crop resist external stresses under different stress conditions. Pseudomonas DY1-3, a strain from the soil under the glacier moss community of Tien Shan No. 1, was selected to investigate its growth-promoting effects. Previous studies have shown that this strain is capable of producing ACC (1-aminocyclopropane-1-carboxylic acid) deaminase. In this experiment, multifunctional biochemical test assays were evaluated to determine their potential as PGPB and their bacterial growth-promoting properties and stress-resistant effects on maize plants were verified through seed germination experiments and pot experiments. The results showed that strain DY1-3 has good salt and drought tolerance, as well as the ability to melt phosphorus, fix nitrogen, and produce iron carriers, IAA, EPS, and other pro-biomasses. This study on the growth-promoting effects of the DY1-3 bacterial strain on maize seeds revealed that the germination rate, primary root length, germ length, number of root meristems, and vigor index of the maize seeds were increased after soaking them in bacterial solution under no-stress, drought-stress, and salt-stress environments. In the potting experiments, seedlings in the experimental group inoculated with DY1-3 showed increased stem thicknesses, primary root length, numbers of root meristems, and plant height compared to control seedlings using sterile water. In the study on the physiological properties of the plants related to resistance to stress, the SOD, POD, CAT, and chlorophyll contents of the seedlings in the experimental group, to which the DY1-3 strain was applied, were higher than those of the control group of seedlings to which the bacterial solution was not applied. The addition of the bacterial solution reduced the content of MDA in the experimental group seedlings, which indicated that DY1-3 could positively affect the promotion of maize seedlings and seeds against abiotic stress. In this study, it was concluded that strain DY1-3 is a valuable strain for application, which can produce a variety of pro-biotic substances to promote plant growth in stress-free environments or to help plants resist abiotic stresses. In addition to this, the strain itself has good salt and drought tolerance, making it an option to help crops grown in saline soils to withstand abiotic stresses, and a promising candidate for future application in agricultural biofertilizers.

Quantitative trait locus mapping of osmotic stress response in the fungal wheat pathogen Zymoseptoria tritici.

Osmotic stress is a ubiquitous and potent stress for all living organisms, but few studies have investigated the genetic basis of salt tolerance in filamentous fungi. The main aim of this study was to identify regions of the genome associated with tolerance to potassium chloride (KCl) in the wheat pathogen Zymoseptoria tritici. A secondary aim was to identify candidate genes affecting salt tolerance within the most promising chromosomal regions. We achieved these aims with a quantitative trait locus (QTL) mapping study using offspring from 2 crosses grown in vitro in the presence or absence of osmotic stress imposed by 0.75 M KCl. We identified significant QTL for most of the traits in both crosses. Several QTLs overlapped with QTL identified in earlier studies for other traits, and some QTL explained trait variation in both the control and salt stress environments. A significant QTL on chromosome 3 explained variation in colony radius at 8-day postinoculation (dpi) in the KCl environment as well as colony radius KCl tolerance at 8 dpi. The QTL peak had a high logarithm of the odds ratio (LOD) and encompassed an interval containing only 36 genes. Six of these genes present promising candidates for functional analyses. A gene ontology (GO) enrichment analysis of QTL unique to the KCl environment found evidence for the enrichment of functions involved in osmotic stress responses.

Classification of soybean genotypes during the seedling stage in controlled drought and salt stress environments using the decision tree algorithm

AbstractSoybean is one of the most important oilseed crops grown worldwide. However, abiotic stresses such as drought and salinity can seriously affect soybean production, especially in tropical climate conditions. To evaluate the adaptability and stability of soybean genotypes under abiotic stress conditions, some studies have proposed a multitrait tool to select stress‐tolerant soybean genotypes through a multitrait stability index (MTSI). This index can be used under stressful environmental conditions to quantify the genotypic stability of soybean cultivars. Our study is based on an unprecedented approach, where we propose to use a machine learning algorithm called ‘Random Forest’ to obtain a classification model based on a decision tree algorithm. The decision tree data structure can be used even by nonexperts facilitating the decision‐making process for genotype selection. The proposed model evaluated the importance of six shoot and root morphological variables and predicted from which controlled growth environment the soybean plants originated. Using this model more than 73% of the genotypic patterns were learned correctly. Besides that, this model can also predict and rank the most critical variables in the development of soybean genotypes, having obtained results very similar to recent field research. The research is important for plant breeders who seek an early selection of soybean seedlings for drought and saline stresses.

Seed Germination and Vegetative Growth of Petunia (Petunia hybrida) Genotypes to Salt Stress

Salinity is a brutal threat to sustainability of crop production and exhibits injurious effect on major plant processes including protein synthesis, cell division and photosynthetic activity. Germination and early growth of plants are most susceptible to salinity effect in comparison to other growth stages. In this context, the seed emergence and early vegetative growth of flowers needs to be tested properly. The pot based study was conducted in Completely Randomized Design (CRD) with three replicates at Sindh Agriculture University Tandojam. The goal of this investigation was to explore the performance of petunia plants to salt stress environment at early growth stage. Two petunia varieties (V1= Prism blue, V2= Hala lop petunia rose) were evaluated against six levels of salt stress (T1 = Canal irrigation water [Control], T2 = 3 dS m-1, T3 = 5 dS m-1, T4 = 7 dS m-1, T5 = 9 dS m-1, T6 = 11 dS m-1).The results showed that there was an inverse effect of salt stress on all the traits examined and with each increased level of salinity in irrigation water; the values of petunia plant traits were significantly decreased. The petunia grown in pots given only canal water (control) revealed better performance for germination and growth attributes. It was further noted that that salt stress up to 3 dS m-1 level was generally tolerated by petunia. Among petunia varieties, Hala lop petunia rose performance was better and showed relative tolerance to salt stress over Prism blue, but in most cases the differences were insignificant (P>0.05).

Morphological and physiological behaviour of sea barley (Hordeum marinum ssp marinum) genotypes originating from Soliman Sebkha under increasing salinity

Evaluation of germplasm in salt stress environment may help identifying salt-tolerant genotypes. In this study, we analyzed the genetic diversity of Hordeum marinum, genotypes originated from Soliman Sebkha in response to salinity (0, 250 and 400 mM) by measuring a set of parameters related to growth, water statue and photosynthetic activity. Results of ANOVA showed that variability of measured parameters was explained by the effects genotypes, treatment and their interaction, with treatment factor recorded the highest values. Salinity significantly reduced the photosynthetic rate and related parameters, including stomatal conductance (gs), intercellular CO2 concentration (Ci), and transpiration (E). Several indices for salt tolerance indices comprising tolerance index (TOL), stress tolerance index (STI) and Salt Tolerance (ST) were calculated based on drought biomass (ADW) under non-stressed and under stress conditions. Results showed that lower values of TOL and higher values of ST and STI indicate the superiority of the genotypes having enough plasticity to respond to extreme conditions. Principal Component Analysis clustered genotypes into sensitive (21.43%), moderately tolerant (50%), and highly tolerant (28.57%) groups, depending on their relative potential to sustain good growth under high salinity. Results indicating sufficient genetic variability for salinity tolerance among the studied genotypes, hence tolerant genotypes can be good candidates in future breeding programs.

Mitigation of Salinity Stress on Soybean Seedlings Using Indole Acetic Acid-Producing Acinetobacter pittii YNA40

Soybean is an important oil crop with multiple uses. Soybeans can grow in various soil types and climates; however, salt stress reduces their yield. Plant growth-promoting microorganisms are an environmentally benign way to combat stress and boost plant tolerance. In the present study, we have identified plant growth-promoting bacteria that can produce indole acetic acid (IAA) and induce distinct growth characteristics in soybean plants under salt stress. The YNA40 isolate was identified as Acinetobacter pittii through 16S rRNA sequencing and phylogenetic analysis. A pure culture of Acinetobacter pittii YNA40 was subjected to chromatographic and mass spectrometry selected-ion monitoring (GC-MS/SIM) for IAA quantification. The results revealed that the YNA40 bacterial strain showed a significantly higher IAA concentration (473.88 ng/mL) at 4% sodium chloride (NaCl). Moreover, in a salt-stress condition, inoculation with Acinetobacter pittii YNA40 was able to induce increased shoot length (23.48%), shoot weight (24%), root length (2.47%), and root weight (44.82%) compared to the uninoculated control. Therefore, soybean seedlings were inoculated with YNA40 to examine their potential for promoting growth and reprogramming after salt stress. Inoculation with YNA40 isolates mitigated the salt stress and significantly improved the growth of the plant, enhanced the chlorophyll contents, and improved the quantum efficiency of chlorophyll fluorescence, total phenolic content, flavonoid content, the diphenyl-1-picrylhydrazyl (DPPH) activity, and antioxidant activities of soybean plants during and after salt stress. The present research demonstrated that the application of the YNA40 isolate is promising for reducing salt stress in soybean plants and helps plants grow better in a salt-stressed environment.

Generation and comprehensive analysis of Synechococcus elongatus–Aspergillus nidulans co-culture system for polyketide production

BackgroundArtificial microbial consortia composed of heterotrophic and photoautotrophic organisms represent a unique strategy for converting light energy and carbon dioxide into high-value bioproducts. Currently, the types of desired bioproducts are still limited, and microbial fitness benefit rendered by paired partner generally needs to be intensified. Exploring novel artificial microbial consortia at a laboratory scale is an essential step towards addressing this unmet need. This study aimed to conduct and analyze an artificial consortium composed of cyanobacterium Synechococcus elongatus FL130 with the filamentous fungus Aspergillus nidulans TWY1.1 for producing fungi-derived secondary metabolite of polyketide neosartoricin B.ResultsPolyketide-producing A. nidulans TWY1.1 substantially ameliorated the growth and the survival of sucrose-secreting cyanobacterium S. elongatus FL130 in salt-stressed environments. Besides sucrose, comparable amounts of other carbohydrates were released from axenically cultured FL130 cells, which could be efficiently consumed by TWY1.1. Relative to axenically cultured FL130, less glycogen was accumulated in FL130 cells co-cultured with TWY1.1, and the glycogen phosphorylase gene catalyzing the first step for glycogen degradation had two-fold expression. Different from axenically cultured filamentous fungi, abundant vacuoles were observed in fungal hyphae of TWY1.1 co-cultured with cyanobacterium FL130. Meanwhile, FL130 cells displayed a characteristic pattern of interacting with its heterotrophic partner, densely dispersing along certain hyphae of TWY1.1. Finally, polyketide neosartoricin B was produced from TWY1.1 in FL130-TWY1.1 co-cultures, which was tightly adjusted by nitrogen level.ConclusionOverall, the results thoroughly proved the concept of pairing cyanobacteria with filamentous fungi to build artificial consortia for producing fungi-derived biomolecules.

Relative performance of wheat genotypes under individual and combined water deficit and salinity stress

Ascertaining the genetic variability and its relationships among valuable genetic resources is important for crop improvement programme. Here, we assessed the response of eleven wheat (Triticum aestivum L.) genotypes using cluster and principal component analysis (PCA) based on morphophysiological data and yield under nine different environments. Wheat genotype WH 1080 maintained higher photosynthetic efficiency under individual stress of 50% water deficit (drought) and 100 mM NaCl (salt), whereas under interactive stresses KRL 370 and KRL 283 were found to be the best genotypes. The highest value of Na+/K+ ratio in shoots was recorded for WH 1080 (1.167) and lowest in KRL 283 (0.612) under combined stresses. Proline accumulation was maximum in KRL 330 (3.17 mg g-1 FW) and minimum in KRL 283 (2.8 mg g-1 FW). Significantly higher reduction (73.4%) was observed in HD 2009 for grain weight/plant at 100 mM NaCl + 50% WD stress treatment whereas minimum reduction of 39.18% was recorded in KRL 370 in comparison to the control treatment. The PCA showed that the first three components comprising about 91% of the total variation for which the variables were analyzed. AMMI model revealed KRL 210 to be stable genotype as being close to center on biplot. E5 environment (100 mM NaCl) was most stable followed by E9 (50% WD + 100 mM NaCl). HD 2888, C-306, HD 2851 and HD 2009 were having positive interaction with E1 (Control) whereas WH 1080 had positive interaction with water deficit environments i.e. E2 and E3 (25 and 50% WD) while KRL 433 had highest positive interaction with combined water deficit and salt stress environments E6, E7, E8 and E9, followed by KRL 370. Similarly, KRL 283, KRL 330, KRL 210 and Kharchia 65 had high positive interaction with saline environments E4 and E5. Findings of the experiment would be beneficial to wheat breeders, specifically the location-specific promising genotypes could possibly be used to develop/breed MAGIC populations to tag genes/alleles conferring drought and salinity tolerance.

Effects of Biochar and Straw Returning on Soil Fungal Community Structure Diversity in Cotton Field with Long-term Brackish Water Irrigation

Brackish water irrigation increases soil salinity and changes the soil environment, which affects the structure and diversity of soil fungi. In this study, the effects of biochar and straw (3.7 t·hm-2 and 6 t·hm-2, respectively) on soil physical and chemical properties and fungal community structure diversity were investigated on the basis of long-term brackish water irrigation. The results showed that compared to the absence of biochar and straw application (control), biochar application significantly increased pH and the contents of total carbon, available potassium, and available phosphorus in soil but significantly decreased the soil conductivity by 20.71%. Straw treatment significantly increased the content of available potassium and phosphorus but significantly decreased the soil bulk density and conductivity by 4.17% and 64.50%, respectively. The biochar and straw treatment showed an increasing trend in the Chao1 index and ACE index of the fungal community but a decreasing trend in the Shannon index and Simpson index. The dominant fungal phyla in the soil were Ascomycota, Mortierellomycota, Basidiomycota, Chytridiomycota, and Glomeromycota. The dominant fungal genera were Chaetomium, Gibberella, Fusarium, Idriella, and Mortierella. Biochar and straw were applied to increase the relative abundance of Ascomycota, Mortierellomycota, Basidiomycota, Glomeromycota, and Chaetomium. However, the relative abundance of Chytridomycota, Gibberella, and Idriella decreased. LEfSe analysis showed that biochar application and straw returning decreased the number of potential biomarkers in fungal communities. RDA results showed that soil fungal community structure was significantly correlated with EC1:5 and TN. Brackish irrigation had adverse effects on soil, in which EC1:5and TN were the main factors driving the change in soil fungal community structure. The soil fungal community adapted to a salt-stress environment through the improvement of soil by biochar and straw.