Screening and identification of salt tolerance soybean varieties and germplasms

Soil salinization is a globally prevalent abiotic environmental stress.The imbalance of ions caused by high concentrations of sodium chloride results in a 40%reduction in soybean yield.Soybean,as an important crop for soil quality improvement,necessitates the identification of salt-tolerant varieties and germplasms to effectively utilize and enhance saline-alkali land.In this study,we assessed the salt tolerance of 435 soybean varieties and germplasms during the seedling stage.Among them,Qihuang34,You2104,Hongzhudou,Pamanheidou,and Osage exhibited grade 1 salt tolerance rates surpassing other tested materials.Furthermore,Hongzhudou and Qihuang34 demonstrated higher salt tolerance during germination and emergence stages based on their elevated rates of emergence,salt tolerance index,chlorophyll content,and shoot fresh weights.Overall findings provide valuable resources for molecular breeding efforts aimed at developing salt-tolerant soybean varieties suitable for cultivation in saline-alkali soils.

Multidimensional evaluation of salt tolerance in groundnut genotypes through biochemical responses

The manuscript explores the complex interplay between groundnut genotypes,salt tolerance and hormonal influence,shedding light on the dynamic responses of three specific groundnut genotypes,KDG-128,TG-37 A and GG-20,to salt treatments and gibberellic acid(GA3).The study encompasses germination,plant growth,total protein content and oil content as key parameters.Through comprehensive analysis,it identifies TG-37 A and KDG-128 as salt-tolerant genotypes,and GG-20 as salt-susceptible genotypes,which highlighting the potential for targeted breeding efforts to develop more resilient groundnut varieties.Moreover,the quantification of protein and oil content under different treatments provides vital data for optimizing nutritional profiles in groundnut cultivars.Principal Component Analysis(PCA) underscores the significance of the first principal component(PC1)in explaining the majority of variance,capturing primary trends and differences in plant length.Analysis of Variance(ANOVA) and hierarchical analysis confirm the presence of statistically significant differences in protein and oil content among the genotypes.Pearson's correlation coefficient matrix analysis reveals strong positive correlations between plant length and protein content,plant length and oil content,and a moderately positive correlation between protein content and oil content.These findings provide valuable insights into groundnut physiology,salt tolerance,and nutritional composition,with implications for future research in sustainable agriculture and crop improvement.

Soaking Rice Seeds in High Concentration Salt Solution Improved Salt Tolerance at the Seedling Stage

[Objectives]This study was conducted to enhance the salt tolerance of current rice varieties at the seedling stage and fulfill the urgent requirement for salt-tolerant rice varieties in coastal tidal flats.[Methods]Four high-generation stable rice lines with diverse salt tolerance were employed as test materials,and four NaCl concentration gradients were established for seed soaking treatment.[Results]The seedling survival rate of line 151465 underwent significant alterations after soaking with four different salt concentrations,and the survival rate was the highest after treatment with 1.8%NaCl for 1 d,reaching 65.2%.The average survival rate of other three lines with different salt tolerance reached 62%after soaking with 1.8%NaCl for 1 d,which was significantly higher than those of the 2.2%NaCl and 0%NaCl treatments.[Conclusions]This study provides a basis for reducing the effect of abiotic stress on rice growth and development and improving the utilization rate of saline-alkali land.

Advances in deciphering salt tolerance mechanism in maize

Maize(Zea mays L.)is a global cereal crop whose demand is projected to double by 2050.Along with worsening of farmland salinization,salt stress has become a major environmental threat to the sustainability of maize production worldwide.Accordingly,there is an urgent need to decipher salt-tolerant mechanisms and facilitate the breeding of salt-tolerant maize.As salt tolerance is a complex trait regulated by multiple genes,and maize germplasm varies widely in salt tolerance,efforts have been devoted to the identification and application of quantitative-trait loci(QTL)for salt tolerance.QTL associated with ion regulation,osmotic tolerance,and other aspects of salt tolerance have been discovered using genomewide association studies(GWAS),linkage mapping,and omics-based approaches.This review highlights recent advances in the molecular-level understanding of salt stress response in maize,in particular in(a)the discovery of salt-tolerance QTL,(b)the mechanisms of salt tolerance,(c)the development of salttolerant maize cultivars,and(d)current challenges and future prospects.

OsMas1,a novel maspardin protein gene,confers tolerance to salt and drought stresses by regulating ABA signaling in rice

Drought and salt stresses,the major environmental abiotic stresses in agriculture worldwide,affect plant growth,crop productivity,and quality.Therefore,developing crops with higher drought and salt tolerance is highly desirable.This study reported the isolation,biological function,and molecular characterization of a novel maspardin gene,OsMas1,from rice.The OsMas1 protein was localized to the cytoplasm.The expression levels of OsMas1 were up-regulated under mannitol,PEG6000,NaCl,and abscisic acid(ABA) treatments in rice.The OsMas1 gene was introduced into the rice cultivar Zhonghua 11(wild type,WT).OsMas1-overexpression(OsMas1-OE) plants exhibited significantly enhanced salt and drought tolerance;in contrast,OsMas1-interference(OsMas1-RNAi) plants exhibited decreased tolerance to salt and drought stresses,compared with WT.OsMas1-OE plants exhibited enhanced hypersensitivity,while OsMas1-RNAi plants showed less sensitivity to exogenous ABA treatment at both germination and post-germination stages.ABA,proline and K+ contents and superoxide dismutase(SOD),catalase(CAT),peroxidase(POD),and photosynthesis activities were significantly increased.In contrast,malonaldehyde(MDA),hydrogen peroxide(H2O2),superoxide anion radical(O2-··),and Na+ contents were significantly decreased in OsMas1-OE plants compared with OsMas1-RNAi and WT plants.Overexpression of OsMas1 up-regulated the genes involved in ABA signaling,proline biosynthesis,reactive oxygen species(ROS)-scavenging system,photosynthesis,and ion transport under salt and drought stresses.Our results indicate that the OsMas1 gene improves salt and drought tolerance in rice,which may serve as a candidate gene for enhancing crop resistance to abiotic stresses.

Eco-friendly aqueous foam stabilized by cellulose microfibers with great salt tolerance and high temperature resistance

A low-cost eco-friendly aqueous foam,especially the robust foam with great tolerance to high salinity and high temperature,is in great demand in the oil industry,e.g.,oil and gas well or geothermal well drilling.Herein,an ultra-stable aqueous foam was developed using the biodegradable cellulose microfiber(CMF)as a foam stabilizer.The foam stabilized by CMF shows excellent tolerance to the high concentration of NaCl(6.0 wt%)and CaCl_(2)(0.25 wt%)and the related drainage half-life times(T_(0.5))reach 1750 and 2340 s respectively.By contrast,the foams without CMF are completely drained(T_(0.5)=0 s)when NaCl concentration is greater than 6.0 wt%or CaCl_(2) concentration is greater than 0.20 wt%.Notably,T0.5 of the foams stabilized by CMF at these saline concentrations still can maintain above 1000 s even after aging at 120℃ for 16 h,exhibiting an outstanding foam-stabilizing performance at high temperature.Experimental results suggest that the salt and high-temperature tolerance of CMF in foam stabilization is attributed to the electrically uncharged surfaces,the formation of a gel-like structure and the excellent thermal stability.This work not only provides a promising candidate of aqueous foam stabilizer to deal with high temperature and high salinity but also presents a natural-based solution for an environmentally friendly drilling industry in the future.

SlTPP4 participates in ABA-mediated salt tolerance by enhancing root architecture in tomato

Salinity tolerance is an important physiological index for crop breeding.Roots are typically the first plant tissue to withstand salt stress.In this study,we found that the tomato(Solanum lycopersicum)trehalose-6-phosphate phosphatase(SlTPP4)gene is induced by abscisic acid(ABA)and salt,and is mainly expressed in roots.Overexpression of SlTPP4 in tomato enhanced tolerance to salt stress,resulting in better growth performance.Under saline conditions,SlTPP4 overexpression plants demonstrated enhanced sucrose metabolism,as well as increased expression of genes related to salt tolerance.At the same time,expression of genes related to ABA biosynthesis and signal transduction was enhanced or altered,respectively.In-depth exploration demonstrated that SlTPP4 enhances Casparian band development in roots to restrict the intake of Na^(+).Our study thus clarifies the mechanism of SlTPP4-mediated salt tolerance,which will be of great importance for the breeding of salt-tolerant tomato crops.

A cluster of mutagenesis revealed an osmotic regulatory role of the OsPIP1 genes in enhancing rice salt tolerance

Aquaporins play important regulatory roles in improving plant abiotic stress tolerance.To better understand whether the Os PIP1 genes collectively dominate the osmotic regulation in rice under salt stress,a cluster editing of the Os PIP1;1,Os PIP1;2 and Os PIP1;3 genes in rice was performed by CRISPR/Cas9 system.Sequencing showed that two mutants with Cas9-free,line 14 and line 18 were successfully edited.Briefly,line 14 deleted a single C base in both the Os PIP1;1 and Os PIP1;3 genes,and inserted a single T base in the Os PIP1;2 gene,respectively.While line 18 demonstrated an insertion of a single A base in the Os PIP1;1gene and a single T base in both the Os PIP1;2 and Os PIP1;3 genes,respectively.Multiplex editing of the Os PIP1 genes significantly inhibited photosynthetic rate and accumulation of compatible metabolites,but increased MDA contents and osmotic potentials in the mutants,thus delaying rice growth under salt stress.Functional loss of the Os PIP1 genes obviously suppressed the expressions of the Os PIP1,Os SOS1,Os CIPK24 and Os CBL4 genes,and increased the influxes of Na+and effluxes of K^(+)/H^(+)in the roots,thus accumulating more Na+in rice mutants under salt stress.This study suggests that the Os PIP1 genes are essential modulators collectively contributing to the enhancement of rice salt stress tolerance,and multiplex editing of the Os PIP1 genes provides insight into the osmotic regulation of the PIP genes.

The Improvement of Soybean Salt Tolerance by Overexpressed GmPAO1

Polyamines play an important regulatory role during plant growth and development and adversity stress,and polyamine oxidase(PAO)is involved in polyamine catabolism.In this study,an up-regulated polyamine oxidase gene GmPAO1 was obtained by transcriptome sequencing analysis and screening at soybean seedling stages.Also,its expression pattern and function were analyzed.The identification results of transgenic GmPAO1 soybean positive lines showed that the relative expression level of GmPAO1 in the overexpressed lines was increased under salt stress.With increasing stress concentration,the seed germination rate decreased.However,the seed germination rate of the overexpressed lines was significantly higher than that of the control lines,and the phenotypic character of the root systems was also better than that of the control lines.The measurement of superoxide dismutase(SOD)and peroxidase(POD)activities and malondialdehyde and hydrogen peroxide contents revealed that the overexpressed soybean lines significantly increased the SOD and POD activities,significantly reducing the malondialdehyde content.Although the hydrogen peroxide content in the transformed plants gradually increased,the hydrogen peroxide content in the overexpression lines was still lower than that in the gene editing lines.Based on this,it was preliminarily judged that GmPAO1 can improve soybean salt tolerance.

Temperature/salt tolerance and oil recovery of xanthan gum solution enhanced by surface-modified nanosilicas

Amide-and alkyl-modified nanosilicas(AANPs)were synthesized and introduced into Xanthan gum(XG)solution,aiming to improve the temperature/salt tolerance and oil recovery.The rheological behaviors of XG/AANP hybrid dispersions were systematically studied at different concentrations,temperatures and inorganic salts.At high temperature(75C)and high salinity(10,000 mg,L1 NaCl),AANPs increase the apparent viscosity and dynamic modulus of the XG solution,and XG/AANP hybrid dispersion exhibits elastic-dominant properties.The most effective concentrations of XG and AANP interacting with each other are 1750 mg·L^(-1) and 0.74 wt%,respectively.The temperature tolerance of XG solution is not satisfactory,and high temperature further weakens the salt tolerance of XG.However,the AANPs significantly enhance the viscoelasticity the XG solution through hydrogen bonds and hydrophobic effect.Under reservoir conditions,XG/AANP hybrid recovers approximately 18.5%more OOIP(original oil in place)than AANP and 11.3%more OOIP than XG.The enhanced oil recovery mechanism of the XG/AANP hybrid is mainly increasing the sweep coefficient,the contribution from the reduction of oil-water interfacial tension is less.

Cloning of cDNA Encoding Choline Monooxygenase from Suaeda liaotungensis and Salt Tolerance of Transgenic Tobacco

Betaine is a very effective osmoprotectant found in many organisms. In high plants, betaine is synthesized by oxidation of choline in two sequential steps: choline-->betaine aldehyde-->betaine. The first step is catalyzed by choline monooxygenase (CMO). In this study, the full-length CMO cDNA (1 820 bp) was cloned from halophyte Suaeda liaotungensis Kitag by RT-PCR and RACE. It included a 123 bp 5' UTR, a 368 bp 3' UTR and a 1 329 bp open reading frame encoding a 442-amino-acid polypeptide with 77%, 72% and 74% sequence identity compared to CMOs from spinach, sugar beet and Atriplex hortensis, respectively. The CMO open reading frame (ORF) was cloned and the plant expression vector pBI121-CMO was constructed. It was transferred into tobacco ( Nicotiana tabacum L. ev. 89) via Agrobacterium mediation. PCR and Southern blotting analysis showed that the CMO gene was integrated into tobacco genome. Transgenic tobacco plants contained higher amount of betaine than that of control plants and were able to survive on MS medium containing 250 mmol/L NaCl. Relative electronic conductivity demonstrated less membrane damage in transgenic plants as in the wild type.

Relationship Between Polyamine Metabolism in Roots and Salt Tolerance of Barley Seedlings

Plant growth rate (GR), contents of free polyamines (fPAs) and bound polyamines (bPAs) and activities of some key enzymes involved in polyamine (PA) metabolism in the roots of two barley (Hordeum valgare L.) cultivars differing in salt sensitivity were investigated with 0-300 mmol/L NaCl treatments. With 0-200 mmol/L NaCl treatments, activities of arginine decarboxylase (ADC) and transglutaminase (TGase) and PA oxidase (PAO) in the roots of barley seedlings all increased, while TGase and PAO activities decreased slightly at 300 mmol/L NaCl. As a result, free Put (fPut) content increased continuously with increasing concentrations of NaCl, while levels of free Spd (fSpd) and an unknown PA (fPAx) and bPAs (bPut, bSpd and bPAx), as well as (fSpd + fPAx)/fPut ratio rose at 50-200 mmol/L NaCl and reduced at 300 mmol/L NaCl. However, no significant change in the tetra-amine spermine (Spin) content was observed. Statistical analysis showed that GR was very significantly positively correlated with (fSpd + fPAx)/fPut ratios and the contents of bPAs, whereas a significant inverse correlation existed between GR and the ratios of fPA contents to bPA levels. These results showed that, under salt stress, the balance between fSpd, fPAx and fPut levels and an equipoise between fPA and bPA contents in roots were important to salt tolerance of barley seedlings.

Application of Fuzzy Comprehensive Evaluation Method Based on Entropy Weight Theory in Evaluation of Salt Tolerance of Cotton

[Objective] The aim was to propose a new entropy weight fuzzy compre- hensive evaluation method for assessing cotton salt tolerance, realizing the objective, accurate and comprehensive evaluation of salt tolerance of cotton. [Method] A sand culture experiment under salt stress of 150 mmol/L of NaCI was designed. The in- dicator weight was determined with the entropy weight fuzzy comprehensive evalu- ation method, based on the salt injury index of indicators. The salt tolerance of cotton was evaluated comprehensively. [Result] At the germination stage, the entropy and weight of salt injury index of germination energy, vigor index, hypocotyl length and fresh weight were highest, followed by germination rate and germination index, and of root length were lowest. At the seedling stage, the entropy and weight of salt injury index of plasma membrane permeability, root vigor and leaf expansion rate were highest, followed by plant height and net photosynthetic rate, and of shoot dry weight and root dry weight were lowest. The salt tolerance of cotton differed a- mong growth stages and cultivars. Among the 11 cultivars, CCRI-44 and CCRI-75 were steadily salt-tolerant at both germination and seedling stages; CCRI-17, Sumi- an 22, Sumian 15 and Dexiamianl had a stable moderate salt tolerance; while Sumian 12 and Simian 3 were steadily salt-sensitive. [Conclusion] The evaluated result was objective and exact, which indicated that this method could be used in comprehensive evaluation of salt tolerance of cotton.

Winter Wheat Salt Tolerance Appraisal Indices with Varied Mineral Content of Saline Water

[Objective] The aim was to study wheat salt resistance appraisal indicators under the condition of saline water irrigation.[Method] A trial was conducted with five varieties irrigated with saline water at 1,2,4,6,and 8 g/L during 2009-2010 and 2010-2011 in the research station of Dry-land Farming Institute of Hebei Academy of Agricultural and Forestry Sciences.With standardized indicators for measuring treatment,the response relations among different salt stress levels and winter wheat growth index were analyzed in this study.[Result] Under the condition of different salinity of irrigation,relative plant height after jointing stage,relative leaf area index,relative dry matter weight,relative ear number per unit area showed significant differences among treatments and yield showed significant correlation,which can be taken as salt-resistance examination index of wheat.[Conclusion] The results showed that the relative height after jointing stage was recommended as the most practical salt-tolerance appraisal indices,because it was easy to be observed and sensitive to salt stress.

On the Identification and Evaluation of Salt Tolerance of Peanut Germplasm

For screening out salt tolerance germplasm and providing materials for ge- netic research of peanut, based on the indexes including relative germination poten- tial, relative germination rate, relative germination index and salt-injury rate, 128 peanut germplasms were selected for salt-tolerant identification and estimation under 2.5% NaCI. We found significant but various depressing levels of germination rate under salt stress among different germplasms, and only 5% of 128 germplasms were highly resistant to salinity. We also found that the relative germination index was a useful evaluation index for salt tolerance besides salt damage rate and rela- tive germination rate. After all, we comprehensively screened out 7 materials （JS011, JS024, JS125, JS491, JS523, JS524 and JS525） as salt tolerance germplasms for further research. Key

Mechanism of Salt Tolerance in Rice

Shaheen Basma ti was evolved as a salt tolerant fine rice va riety by the Soil Salinity Research Institute,Pindi Bhattian, Pakistan. Water culture studies were conducted to investigate the physiological mechanismexercised by this variety in particular and rice plant in general to face the saline environment. Performanceof this rice variety and the concentration and uptake of ions were studied under stress of three salinity levels(30, 60 and 90 mmol L-1) created with NaCl. Recorded data indicated that shoot dry matter was notsignificantly affected by all the three levels of salinity. However, NaCl levels of 60 and 90 mmol L-1 affectedthe root dry matter significantly. Sodium concentration and uptake was enhanced significantly in root andshoot at the first level of salinity (30 mmol L-1) but thereafter the differences were non-significant, indicatingthe preferential absorption of this cation. The K concentration decreased significantly in shoots at all thelevels. The impact was less pronounced in roots as far as K absorption was concerned. The effect on Ca andMg concentrations was not significant. The values of K:Na, Ca:Na and (Ca+Mg):Na ratios in shoot and rootwere comparatively low under stress conditions, indicating that selective ion absorption may be the principalsalt tolerance mechanism of variety Shaheen Basmati when grown in a saline medium.

Plant salt tolerance and Na^+ sensing and transport

Salinity is a global challenge to agricultural production. Understanding Na^+ sensing and transport in plants under salt stress will be of benefit for breeding robustly salt-tolerant crop species. In this review, first, possible salt stress sensor candidates and the root meristem zone as a tissue harboring salt stress-sensing components are proposed. Then,the importance of Na^+ exclusion and vacuolar Na^+ sequestration in plant overall salt tolerance is highlighted. Other Na^+ regulation processes, including xylem Na^+ loading and unloading, phloem Na^+ recirculation, and Na^+ secretion, are discussed and summarized.Along with a summary of Na^+ transporters and channels, the molecular regulation of Na^+ transporters and channels in response to salt stress is discussed. Finally, some largely neglected issues in plant salt stress tolerance, including Na^+ concentration in cytosol and the role of Na^+ as a nutrient, are reviewed and discussed.

Salt tolerance in rice:Physiological responses and molecular mechanisms

Crop yield loss due to soil salinization is an increasing threat to agriculture worldwide.Salt stress drastically affects the growth,development,and grain productivity of rice(Oryza sativa L.),and the improvement of rice tolerance to salt stress is a desirable approach for meeting increasing food demand.The main contributors to salt toxicity at a global scale are Na^(+)and Cl^(-)ions,which affect up to 50%of irrigated soils.Plant responses to salt stress occur at the organismic,cellular,and molecular levels and are pleiotropic,involving(1)maintenance of ionic homeostasis,(2)osmotic adjustment,(3)ROS scavenging,and(4)nutritional balance.In this review,we discuss recent research progress on these four aspects of plant physiological response,with particular attention to hormonal and gene expression regulation and salt tolerance signaling pathways in rice.The information summarized here will be useful for accelerating the breeding of salt-tolerant rice.

A New Transplanting Approach to Enhance Salt Tolerance of Tree Saplings

A field investigation was conducted to determine the survival and growth rate of eucalyptus (Eucalyptus camaldulensis Dehn.) and guava (Psidium guajava L.) saplings planted in salt-affected soils. The field used was highly saline-sodic in nature with a wide variation in electrical conductivity of the saturated soil extract (ECe), pHs, sodium adsorption ratio (SAR) and gypsum requirement (GR). A randomized complete block design was utilized with three treatments, i.e. T1 = plastic container bags totally removed, T2 = only the plastic container bag's base removed and T3 = plastic container bags un-removed. There were 34 and 8 plants in each block for eucalyptus and guava, correspondingly. The survival rates of eucalyptus and guava saplings were greater than 90%. In addition, gain in eucalyptus height was significantly higher in the T1 treatment where the bags were totally removed while for guava height the treatments were not significant.The gain in girth was not significant for both eucalyptus and guava saplings. With eucalyptus the taproot length was greater than the lateral roots while for guava the lateral roots were longer than the taproots.There was a decrease in the salinity-sodicity of the soils for the upper 30 cm depth under both types of vegetation, indicating that the salts had leached down to the B-horizon.

Haplotype variations in QTL for salt tolerance in Chinese wheat accessions identified by marker-based and pedigree-based kinship analyses

Most modern wheat cultivars were selected on the basis of yield-related indices measured under optimal fertilizer and irrigation inputs.With climate change,land degradation and salinity caused by sea water encroachment,wheat is increasingly subjected to environmental stress.Moreover,expanding urbanization increasingly encroaches upon prime agricultural land in countries like China,and alternative cropping areas must be found.Some of these areas have moderate constraining factors,such as salinity.Therefore,it is important to investigate whether current genetic materials and breeding procedures are maintaining adequate variability to address future problems caused by abiotic stress.In this study,a panel of 307 wheat accessions,including local landraces,exotic cultivars used in Chinese breeding programs and Chinese cultivars released during different periods since1940,were subjected to a genome-wide association study to dissect the genetic basis of salinity tolerance.Both marker-based and pedigree-based kinship analyses revealed that favorable haplotypes were introduced in some exotic cultivars as well as a limited number of Chinese landraces from the 1940 s.However,improvements in salinity tolerance during modern breeding are not as obvious as that of yield.To broaden genetic diversity for increasing salt tolerance,there is a need to refocus attention on local landraces that have high degrees of salinity tolerance and carry rare favorable alleles that have not been exploited in breeding.