Salt Stress Conditions Research Articles

Determination of Salt Stress by Plant Leaf Temperature and Thermal Imaging in Black Cumin Grown Under Different Salt Sources

ABSTRACT Thermal imaging has been used in recent years to determine salinity stress in certain crops. However, no information is available on this regarding black cumin (Nigella sativa L.). The main purpose of this study was to investigate the determinability of the salt stress on black cumin by thermal imaging. The leaf temperature values were obtained by acquiring the thermal images for black cumin grown under different irrigation water salinity levels (0.6 as control, 1.5, 2.5, and 5.0 dS/m) prepared for different salt sources (CaCl2, MgCl2, NaCl, Ca(NO3)2, MgSO,4 and Na2SO4). Plant leaf temperatures averaged over all irrigation water salinity levels did not show a significant difference among salt sources. On the other hand, plant leaf temperatures independent of the salt sources significantly increased with increasing salinity levels. The order for salinity levels in terms of their effect on the leaf temperature of black cumin was determined as 5.0 dS/m > 2.5 dS/m > 1.5 dS/m ≥ 0.6 dS/m. The highest leaf temperature was obtained under 5.0 dS/m salinity level with CaCl2, MgCl2, Ca(NO3)2, MgSO4, and Na2SO4 salt sources, but the values for MgSO4 and Na2SO4 salt sources were not significantly different from those under 2.5 dS/m salinity. In addition, a strong-negative relationship between plant water consumption and leaf temperature under CaCl2 and MgSO4 and a moderate-negative relationship under MgCl2 and NaCl salt sources were determined. The results of this study showed that the plant leaf temperature values obtained by thermal imaging reflected salt stress conditions, especially under high salinity levels.

Association of GhGeBP genes with fiber quality and early maturity related traits in upland cotton

Transcription Factors (TFs) are key regulators of how plants grow and develop. Among the diverse TF families, the Glabrous-enhancer binding protein (GeBP) family plays a key role in trichome initiation and leaf development. The specific roles of GeBP TFs in plants remain largely unexplored, although GeBP transcription factors play important roles in plants. This study identified 16 GhGeBP genes in Gossypium hirsutum, ranging from 534 bp (GhGeBP14) to 1560 bp (GhGeBP2). Phylogenetic analysis grouped 16 GhGeBP genes clustered into three subgroups, unevenly distributed across 14 chromosomes. Analysis of the cis-acting elements revealed 408 motifs in the 2 kb upstream regions of the promoters, including stress-responsive, phytohormone-responsive, and light-responsive elements. Tissue-specific expression analysis showed 8 GhGeBP genes were highly expressed across all tissues, while GhGeBP4 and GhGeBP12 were down-regulated under conditions of drought, salt, cold, and heat stress. A genome-wide association study (GWAS) identified GhGeBP4 was associated with fiber micronaire (FM) and fiber strength (FS), while GhGeBP9 was linked to the node of the first fruiting branch (NFFB) and flowering time (FT). Haplotype analysis revealed that GhGeBP4-HAP2 exhibited higher fiber quality traits, while GhGeBP9-HAP2 was associated with early maturity. The results of this study offer significant insights that are worthy of further investigation into the role of the GhGeBP gene family in G. hirsutum and promising targets for marker-assisted selection strategies in cotton breeding programs, particularly for improving fiber quality and early maturity traits.

Boosting Stevia's sweetness: Growth regulators mitigate salt stress and enhance steviol glycosides

Stevia rebaudiana Bertoni is a plant species with sweet-tasting leaves that can be used as a natural, low-calorie sweetener with potential health benefits. Salt stress can reduce plant growth and productivity, but the application of growth regulators like salicylic acid (SA), methyl jasmonate (MeJ), and spermidine (Spd) can manage various plant abiotic stresses and improve plant growth and productivity. In this work, we investigated the role of exogenous SA, MeJ, and Spd in conferring salt stress tolerance in Stevia by analyzing plant growth, chlorophyll (Chl), total phenolic, total carotenoid content, antioxidant defense system and steviol glycosides. The aim of a recent study was to assess the effects of these regulators on Stevia plants under both individual and combined salt stress conditions. Foliar application of these regulators improved plant growth under salt stress, with moderate salinity stress increasing glycoside compounds. SA was most effective in increasing rebaudioside A (Reb A), while MeJ + Spd combination was best for increasing stevioside (Stv) content. Individual applications of Spd, MeJ, and SA significantly impacted plant growth and antioxidant content, although their combined use was less effective. Spd application under salt stress yielded the highest increases in total carotenoid and Chl a content, while MeJ and Spd together significantly boosted Chl b content. The study found that SA enhanced superoxide dismutase (SOD) activity and reduced catalase (CAT) activity under salt stress, whereas MeJ alone increased both CAT and SOD activity. The distinct responses to Spd, SA, and MeJ suggest varied mechanisms in oxidative stress-induced antioxidant production. Overall, the use of these growth regulators can improve the growth, yield, and nutritional value of Stevia under salt stress, offering significant implications for agriculture and food security.

Estimation of Malondialdehyde Content in Medicago truncatula under Salt Stress Based on Multi-Order Spectral Transformation Characteristics

Salt stress is a significant abiotic factor affecting the growth and development of alfalfa. Malondialdehyde (MDA) serves as a critical biomarker for assessing alfalfa’s salt tolerance. Traditional methods for measuring MDA are often time-consuming and labor-intensive. Recent advances in remote sensing technology have made non-destructive estimation of metabolites feasible, positioning the accurate estimation of MDA content in alfalfa as a key focus in intelligent breeding. To address the challenge of detecting subtle changes in MDA content, this study developed a partial least squares regression (PLSR) model specifically for Medicago truncatula. This study utilized leaf reflectance hyperspectral data across the visible near-infrared–shortwave infrared (VIR-NIR-SWIR) spectrum, applying multi-order spectral transformation methods, including continuous wavelet transform (CWT), fractional differential (FD), and multi-granularity spectral segmentation (MGSS). Feature selection techniques, such as sequential forward selection (SFS), Least-Squares Boosting (LSBoost), and feature selection using neighborhood component analysis for regression (FSRNCA), were employed to enhance the efficiency of the MDA estimation. The findings revealed that the optimal PLSR model for MDA estimation was achieved by integrating CWT features across orders 1–30 with the SFS method. This model demonstrated robust estimation capabilities under varying salt stress conditions, significantly outperforming the original spectral data (R2 = 0.654, RMSE = 22.567 vs. R2 = 0.242, RMSE = 33.411). A comparative analysis of feature selection methods confirmed that SFS was the most effective for estimating MDA content in alfalfa. These results provide valuable insights and methodologies for MDA estimation and evaluating salt tolerance in alfalfa.

Genome-wide identification and expression analysis of the OSC gene family in Platycodon grandiflorus

Platycodon grandiflorus stands as one of the most extensively utilized traditional Chinese medicinal herbs, with triterpenoids and their derivatives serving as its primary medicinal components. Oxido squalene cyclase (OSC), serving as a crucial enzyme in the triterpenoid synthesis pathway, has the capability to enzymatically generate significant quantities of sterols and triterpenoid intermediates. While the OSC gene family has been identified in numerous species, bioinformatics research on this family remains scant. Presently, the specific members of this gene family in Platycodon grandiflorus have yet to be definitively determined. In this study, we successfully identified a total of 15 PgOSC genes within the genome of Platycodon grandiflorus by conducting homology comparisons. These genes were discovered to be unevenly distributed across the five chromosomes of the species, organized in the form of gene clusters. Subsequently, we conducted a thorough analysis of the OSC gene family’s evolutionary relationship by constructing a phylogenetic tree. Other characteristics of PgOSC family members, including gene structure, conserved motifs, protein three-dimensional structure, subcellular localization, and cis-acting elements were thoroughly characterized. Furthermore, We analyzed the expression of PgOSC gene in different tissues of Platycodon grandiflorus by qRT-PCR, and found that the expression of PgOSC genes in root was higher than that in stem and leaf. Upon comparing the effects of salt, heat, and drought treatments, we observed a significant induction of PgOSC gene expression in Platycodon grandiflorus specifically under salt stress conditions. In summary, this study comprehensively identified and analyzed the OSC gene family, aiming to provide basic biological information for exploring the members of PgOSC gene family.

Genome-Wide Analysis of the MAPKKK Gene Family Under Abiotic Stresses in Moso Bamboo (Phyllostachys edulis)

Mitogen-activated protein kinase kinase kinases (MAPKKKs) are the upstream components of MAPK cascades and are involved in mediating stress responses and developmental processes. Although MAPKKK genes have been investigated in many plants, the identification and characterization of MAPKKKs in moso bamboo were still limited. Here, 134 MAPKKKs were identified as unevenly distributed on 23 chromosomes (except for chromosome 1) of moso bamboo and divided into three subfamilies by phylogenetic analysis. The gene structure and conserved motif of PeMAPKKKs were investigated. The expansions of PeMAPKKKs were driven by whole-genome duplication (WGD) or segmental duplication events. The duplicated gene pairs were under purifying selection based on the Ka/Ks ratios, suggesting they underwent functional conservation. Most PeMAPKKKs contained cis-elements related to development, hormones, and stress responses. Tissue expression patterns showed that PeMAPKKKs had multiple expression patterns. The qPCR analysis showed distinct expression patterns of PeMAPKKKs under drought, salt, and cold stress conditions. Taken together, this study provides a solid foundation for future functional characterizations of MAPKKKs and identifies candidate stress-responsive genes for further study in moso bamboo.

Application of Silicon Iron and Silver Nanoparticles Improve Vegetative Development and Physiological Characteristics of Boysenberry Plants Grown under Salinity Stress In Vitro Cultivation Conditions

Salinity is one of the most important abiotic stress factors that affect plant growth and limit agricultural productivity. In this study, the effects of iron (FeNP), silver (AgNP), and silicon dioxide (SiNP) nanoparticles on the morphological and physiological parameters of in vitro boysenberry plants grown under salinity stress (NaCl) were investigated. According to our study results, higher values were obtained from SiNP application in terms of shoot development parameters; FeNP application was found to be more successful for root development; AgNP application was effective in terms of SPAD, leaf relative water content (LRWC), and relative growth rate (RGR); and FeNP application increased superoxide dismutase (SOD) and catalase (CAT) enzyme activities. Salt stress significantly affected root development, SPAD values, LRWC and RGR, and SOD and CAT enzyme activities. As a result, under salt stress conditions, SiNP, FeNP, and AgNP applications can significantly reduce the negative effects of stress and promote the vegetative development of the plant compared to control conditions.

HOS1 ubiquitinates SPL9 for degradation to modulate salinity-delayed flowering.

Soil salinity is a serious environmental threat to plant growth and flowering. Flowering in the right place, at the right time, ensures maximal reproductive success for plants. Salinity-delayed flowering is considered a stress coping/survival strategy and the molecular mechanisms underlying this process require further studies to enhance the crop's salt tolerance ability. A nuclear pore complex (NPC) component, HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENE 1 (HOS1), has been recognized as a negative regulator of plant cold responses and flowering. Here, we challenged the role of HOS1 in regulating flowering in response to salinity stress. Interestingly, we discovered that HOS1 can directly interact with and ubiquitinate transcription factor SPL9 (SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 9) to promote its protein degradation in response to salinity stress. Moreover, we demonstrated that HOS1 and SPL9 antagonistically regulate plant flowering under both normal and salt stress conditions. HOS1 was further shown to negatively regulate the expression of SPLs and several key flowering genes in response to salinity stress. These results jointly revealed that HOS1 is an important integrator in the process of modulating salinity-delayed flowering, thus offering new perspectives on a salinity stress coping strategy of plants.

Influence of drought and salt stress on almond nutrition

Increased drought and salinity is a threat to agriculture in arid and semiarid zone worldwide. Almond is nutritious, rich in minerals protein and fiber with increasing world demand and production. The objective was to determine the effect of drought and salinity stress on nutrient concentrations in almond trees. Almond is known as sensitive to salt stress compared to other trees. There are limited studies on almond nutrition uptake under salt and drought stress conditions. This study had three drought and four salinity levels, and combined applications for a total of 12 treatments each with three replications. Drought increased K, Mg, Ca, Na and Cl concentrations in leaves, yet, decreased B concentrations. Similarly under salinity, almond leaves increased in K, Mg and Ca concentrations (as well as in Na and Cl). This study showed that the nutrient uptake varies under drought and salt stress conditions. Mineral nutrition should be taken into consideration, fertilization needs to account for stress factors.

Germination of chief fire seeds cockscomb cultivar under saline stress conditions induced by sodium chloride

Cockscomb plant, Chief fire cultivar, is used as an ornamental, medicinal and non-conventional food plant (NCFP) and is cultivated from the north to the center-west of Brazil; however, these areas suffer from adverse environmental factors such as salinity stress. The objective of this study was to evaluate the seed germination performance and vigor of Celosia cristata L. var. Chief Fire seedlings exposed to salinity during the germination phase. To carry out the work, C. cristata seeds were sown in gerboxes conditioned to increasing doses of sodium chloride (NaCl), obtained by dissolving the salt in distilled water, obtaining electrical conductivities of 2.0; 4.0; 6.0 and 8.0 dS.m-1, constituting the treatments. An additional group was treated only with distilled water and was used as a control for the experiment. The experiment was conducted in a completely randomized design, with a total of five treatments and four replicates of 25 seeds. The parameters assessed were: first germination count, germination, germination speed index (GVI), mean germination time (MGT), length of aerial part and primary root. The data was submitted to analysis of variance and the means were compared using the Scott-Knott test at 5% significance. Based on the results obtained, it can be concluded that the conditions of salt stress induced by NaCl were not harmful to the germination of C. cristata, presenting itself as a species tolerant to water salinity during seed germination, since the variables analyzed showed no signs of deleterious effects as the salt concentration was increased.

Methyl jasmonate mitigates biochemical and phytochemical changes in salt stressed Stevia rebaudiana plants

This study explored the effects of salt stress on growth, oxidative stress, and steviol glycoside content in Stevia rebaudiana Bertoni plants cultivated in soil supplemented with methyl jasmonate (MeJA). Stevia plants were cultivated under normal and salt stress conditions, with and without MeJA supplements of 30 ?M, 60 ?M, and 120 ?M. Samples were harvested after the 1st, 3rd, 5th, 10th, and 15th day of treatment. The levels of chlorophyll (p<0.0001), carotenoids (p<0.0001), and antioxidant enzymes such as catalase (p<0.0001), superoxide dismutase (p<0.0001), APX (p<0.0001), and glutathione reductase (p<0.0001) were observed. The quantification of steviol glycosides, including stevioside (p<0.0001) and rebaudioside-A (p<0.0001), was studied by the most advanced hyphenated technique, LC-MS/MS. The study revealed that the oxidative stress responses were significantly improved in MeJA-treated plants compared to salt-stress control plants. The level of production of phenols (p<0.0001), flavonoids, total sugar, reducing sugar, and steviol glucosides was significantly altered in salt-stress plants. MeJA showed a dose- and time-dependent significant effect on the improvement of these factors over salt stress. In conclusion, MeJA not only improves the growth of plants but also reduces oxidative stress and enhances the level of phytochemicals under saline stress.

Genome-Wide Identification, Phylogenetic, and Expression Analysis of Jasmonate ZIM-Domain Gene Family in Medicago Sativa L.

JASMONATE ZIM domain (JAZ) proteins, inhibitors of the jasmonic acid (JA) signaling pathway, are identified in different plants, such as rice and Arabidopsis. These proteins are crucial for growth, development, and abiotic stress responses. However, limited information is available regarding the JAZ family in alfalfa. This study identified 11 JAZ genes (MsJAZs) in the "Zhongmu No.1" reference genome of alfalfa. The physical and chemical properties, chromosome localization, phylogenetic relationships, gene structure, cis-acting elements, and collinearity of the 11 MsJAZ genes were subsequently analyzed. Tissue-specific analysis revealed distinct functions of different MsJAZ genes in growth and development. The expression patterns of MsJAZ genes under salt stress conditions were validated using qRT-PCR. All MsJAZ genes responded to salt stress, with varying levels of upregulation over time, highlighting their role in stress responses. Furthermore, heterogeneous expression of MsJAZ1 in Arabidopsis resulted in significantly lower seed germination and survival rates in OE-2 and OE-4 compared to the WT under 150 mM NaCl treatment. This study establishes a foundation for further exploration of the function of the JAZ family and provides significant insights into the genetic improvement of alfalfa.

ATAC sequencing and transcriptomics reveal the impact of chromatin accessibility on gene expression in Tritipyrum under salt-stress conditions

ATAC sequencing and transcriptomics reveal the impact of chromatin accessibility on gene expression in Tritipyrum under salt-stress conditions

Assessing of sugar beet Seed adaptation under salt and drought stress conditions with coating technology based on Fuzzy inference system

Sustainability in crop production is highly dependent on favorable indicators of germination and seedling establishment. In this research seed coating different treatments data prepared and membership function defined in fuzzy inference system then used rule editor tool for determining parameters weight for achieved the best coating treatment in salinity and drought stress conditions. Seed coating formulations were investigated in laboratory and greenhouse experiments for their potential to increase maximum germination, germination rate, germination uniformity, and seedling growth of sugar beet seeds. Sugar beet seeds were coated with different compounds and combinations, including micro- (Fe, Zn, Cu, Mn, Co, Mo) and macro- (N, P, K) nutrients, humic acid, gibberellic acid, kaolin, and chitosan. Coated and non-coated sugar beet seeds were evaluated for germination and seedling growth after 10 and 21 days, respectively. In total, 30 different treatments were used to assess the effects of seed coating treatments. In laboratory experiments, sugar beet seeds were placed on paper in Petri dishes and maintained in a germinator at 25 °C. Sodium chloride and polyethylene glycol 8000 were used to apply salinity and drought stresses at three levels each and achieve the results of seed coatings on reducing the effects of salinity and drought stresses. To determine the indices related to emergence and establishment, cultivation trays were utilized with four replications for each treatment. The trays were kept inside a greenhouse. Coating treatments significantly improved total germination percentage, germination rate, seedling growth, and uniformity compared with the non-treated controls. In all treatments, polyvinylpyrrolidone was utilized as a binder. The best treatment with respect to germination and seedling growth indices was number 21 (micro and macronutrients, humic acid, gibberellic acid) in salinity and drought stress conditions. The results by fuzzy inference system illustrated that micronutrients, humic acid, and gibberellic acid create the best seed coating for sugar beet seeds, especially when combined at the specified amounts.

Overexpression of Auxin/Indole-3-Acetic Acid Gene TrIAA27 Enhances Biomass, Drought, and Salt Tolerance in Arabidopsis thaliana

White clover (Trifolium repens L.) is an important forage and aesthetic plant species, but it is susceptible to drought and heat stress. The phytohormone auxin regulates several aspects of plant development and alleviates the effects of drought stress in plants, including white clover, by involving auxin/indole acetic acid (Aux/IAA) family genes. However, Aux/IAA genes and the underlying mechanism of auxin-mediated drought response remain elusive in white clover. To extend our understanding of the multiple functions of Aux/IAAs, the current study described the characterization of a member of the Aux/IAA family TrIAA27 of white clover. TrIAA27 protein had conserved the Aux/IAA family domain and shared high sequence similarity with the IAA27 gene of a closely related species and Arabidopsis. Expression of TrIAA27 was upregulated in response to heavy metal, drought, salt, NO, Ca2+, H2O2, Spm, ABA, and IAA treatments, while downregulated under cold stress in the roots and leaves of white clover. TrIAA27 protein was localized in the nucleus. Constitutive overexpression of TrIAA27 in Arabidopsis thaliana led to enhanced hypocotyl length, root length, plant height, leaf length and width, and fresh and dry weights under optimal and stress conditions. There was Improved photosynthesis activity, chlorophyll content, survival rate, relative water content, endogenous catalase (CAT), and peroxidase (POD) concentration with a significantly lower electrolyte leakage percentage, malondialdehyde (MDA) content, and hydrogen peroxide (H2O2) concentration in overexpression lines compared to wild-type Arabidopsis under drought and salt stress conditions. Exposure to stress conditions resulted in relatively weaker roots and above-ground plant growth inhibition, enhanced endogenous levels of major antioxidant enzymes, which correlated well with lower lipid peroxidation, lower levels of reactive oxygen species, and reduced cell death in overexpression lines. The data of the current study demonstrated that TrIAA27 is involved in positively regulating plant growth and development and could be considered a potential target gene for further use, including the breeding of white clover for higher biomass with improved root architecture and tolerance to abiotic stress.

Agro-Physiological and DNA Methylation Responses to Salinity Stress in Wheat (Triticum aestivum L.), Aegilops cylindrica Host, and Their Introgressed Lines

Bottlenecks, including limited genetic variation and the ongoing loss of genetic diversity, have hindered the development of modern wheat cultivars., making it crucial to use genetic diversity from wild relatives to improve wheat’s adaptation to abiotic stress, such as salinity. This study assessed the phenotypic and epigenetic variation of introgressed wheat lines (BC4F2) derived from hybridizing two wheat cultivars with Aegilops cylindrica (AC). This study assessed the phenotypic and epigenetic variation of 156 introgressed wheat lines (BC4F2) derived from hybridization between wheat cultivars “Chinese Spring” (CS) and “Roshan” (R) and Aegilops cylindrica (AC). These lines and their recurrent parents (total of 158) were evaluated under normal and saline field conditions for the agronomic traits and stress tolerance indices. The data were used to select the most tolerant and most sensitive lines. Then, the selected BC4F2 lines and their parents (AC, CS, and R) were subjected to physiological, DNA cytosine methylation, and expression analysis of HKT1;5, NHX1, and SOS1 genes under control and salt stress conditions. Agro-physiological, epigenetic, and gene expression analyses showed the significant effects of salt stress and genetic background, as well as the differential response of the BC4F2 lines to salt stress. The variations in leaf and root K, Na, and K/Na ratios, and leaf Chla, Chlb, Car, and MDA levels, unlike DPPH radical scavenging levels, between salt-tolerant and salt-sensitive BC4F2 lines under saline conditions indicated a substantial distinction in salinity tolerance responses. RT-qPCR indicated higher expression levels of NHX1 and SOS1 genes in the leaf and root tissues of tolerant lines than those of sensitive lines. Global leaf and root DNA methylation analysis revealed the significant effects of salinity on the methylation modifications and confirmed the successful introgression of the salt-tolerance epigenome from Ae. cylindrica into wheat. Exploiting the genetic diversity of wild wheat relatives is a crucial goal for increasing genetic and epigenetic variation to enhance plant adaptation to salt stress.

Silver nanoparticles synthesized from marine algae Spatoglossum asperum: Antioxidant properties and seed germination enhancement

Biosynthesized silver nanoparticles (AgNPs) have shown promising potential in plant growth under stressed conditions but marine algae synthesized AgNPs still remain least explored. In the current study, AgNPs have been synthesis by using the aqueous extract of marine brown alga Spatoglossum asperum as a reducing medium and their application in the growth of Vigna radiata seeds under salt stress conditions was studied. The antioxidant potential of AgNPs in comparison with algal extract was also assessed. The AgNPs synthesized using the algal extract was characterized by means of UV–Vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray (XRD) diffraction analysis, Field emission scanning electron microscopy (FE-SEM) and Energy dispersive X-ray spectroscopy (EDS). The FE-SEM and EDS results confirmed the formation of multi-shaped (spherical, cubical and nano-clusters) particles with average size of 43.65 nm. Developed AgNPs showed a surface plasmon resonance band at 425 nm and a face-centric cubic crystallographic structure with an average crystallite size of 23.05 nm. The FTIR spectrum ensured the involvement of di and polysulphides in the synthesis of nanoparticles. The results revealed that the algal synthesized AgNPs showed superior antioxidant activity compared to the algal extract alone and significantly enhanced seed germination in Vigna radiata under both normal and saline conditions. These findings suggest that Spatoglossum asperum derived AgNPs could play a pivotal role in agriculture and environmental sustainability.

Mitigation of salt stress in Sorghum bicolor L. by the halotolerant endophyte Pseudomonas stutzeri ISE12.

Increasing soil salinity, exacerbated by climate change, threatens seed germination and crop growth, causing significant agricultural losses. Using bioinoculants based on halotolerant plant growth-promoting endophytes (PGPEs) in modern agriculture is the most promising and sustainable method for supporting plant growth under salt-stress conditions. Our study evaluated the efficacy of Pseudomonas stutzeri ISE12, an endophyte derived from the extreme halophyte Salicornia europaea, in enhancing the salinity tolerance of sorghum (Sorghum bicolor L.). We hypothesized that P. stutzeri ISE12 would improve sorghum salt tolerance to salinity, with the extent of the increase in tolerance depending on the genotype's sensitivity to salt stress. Experiments were conducted for two sorghum genotypes differing in salinity tolerance (Pegah - salt tolerant, and Payam - salt sensitive), which were inoculated with a selected bacterium at different salinity concentrations (0, 100, 150, and 200 mM NaCl). For germination, we measured germination percentage and index, mean germination time, vigor, shoot and root length of seedlings, and fresh and dry weight. In pot experiments, we assessed the number of leaves, leaf area, specific leaf area, leaf weight ratio, relative root weight, plantlet shoot and root length, fresh and dry weight, proline and hydrogen peroxide concentrations, and peroxidase enzyme activity. Our study demonstrated that inoculation significantly enhanced germination and growth for both sorghum genotypes. The salinity-sensitive genotype (Payam) responded better to bacterial inoculation during germination and early seedling growth stages, showing approximately 1.4 to 1.8 times greater improvement than the salinity-tolerant genotype (Pegah). Payam also displayed better performance at the plantlet growth stage, between 1.1 and 2.6 times higher than Pegah. Furthermore, inoculation significantly reduced hydrogen peroxide, peroxidase activity, and proline levels in both sorghum genotypes. These reductions were notably more pronounced in Payam, with up to 1.5, 1.3, and 1.5 times greater reductions than in Pegah. These results highlight the efficacy of P. stutzeri ISE12 in alleviating oxidative stress and reducing energy expenditure on defense mechanisms in sorghum, particularly benefiting salt-sensitive genotypes. Our findings highlight the potential of the bacterial endophyte P. stutzeri ISE12 as a valuable bioinoculant to promote sorghum growth under saline conditions.

Enhancing Plant Stress Tolerance: The Role of LcWRKY40 Gene in Drought and Alkaline Salt Resistance in Tobacco and Yeast.

Leymus chinensis, a halophytic perennial grass belonging to the Poaceae family, thrives in saline-alkali grasslands and harbors a rich repository of resistance-related genetic resources. This study focused on deciphering the stress-responsive mechanisms of L. chinensis by conducting transcriptomic sequencing under NaHCO3 stress, which resulted in the annotation of a segment corresponding to the 51WRKY gene. The alkali-induced gene LcWRKY40 (QIG37591) was identified by phylogenetic analysis. Real-time quantitative PCR analysis was performed on L. chinensis plants subjected to PEG6000 and alkaline salt (NaHCO3) stress, and the results indicated that the LcWRKY40 gene was upregulated in both the leaves and roots. The localization of the LcWRKY40 protein was confirmed by the use of green fluorescent protein (GFP) fusion technology in transformed rice protoplast cells. The GAL4-driven transformation of the LcWRKY40 gene in INVScI yeast cells, which exhibited enhanced tolerance upon overexpression of the LcWRKY40 gene under mannitol and alkaline salt (NaHCO3) stress conditions. Under drought stress using mannitol, the fresh weight of Nicotiana tabacum overexpressing the LcWRKY40 gene was significantly higher than that of wild-type(WT) tobacco. Through drought and salt alkali stress, we found that overexpressed tobacco at different stages always outperformed the wild type in terms of fresh weight, SOD, MDA, and Fv/Fm. This study provides preliminary insights into the involvement of the LcWRKY40 gene in responding to drought and alkaline salt stresses, highlighting its role in enhancing plant resistance to drought and saline-alkaline conditions. These findings lay the foundation for future molecular breeding strategies aimed at improving grass resistance from different aspects.

Genome-Wide Identification and Expression Analysis of the Cyclic Nucleotide-Gated Channel Gene Family in Zoysia japonica under Salt Stress.

Salt stress severely inhibits plant growth. Understanding the mechanism of plant salt tolerance is highly important to improving plant salt tolerance. Previous studies have shown that nonselective cyclic nucleotide-gated ion channels (CNGCs) play an important role in plant salt tolerance. However, current research on CNGCs mainly focuses on CNGCs in glycophytic plants, and research on CNGCs in halophytes that exhibit special salt tolerance strategies is still scarce. This study used the halophilic plant Zoysia japonica, an excellent warm-season turfgrass, as the experimental material. Through bioinformatics analysis, 18 members of the CNGC family were identified in Zoysia japonica; they were designated ZjCNGC1 through ZjCNGC18 according to their scaffold-level chromosomal positions. ZjCNGCs are divided into four groups (I-IV), with the same groups having differentiated protein-conserved domains and gene structures. ZjCNGCs are unevenly distributed on 16 scaffold-level chromosomes. Compared with other species, the ZjCNGCs in Group III exhibit obvious gene expansion, mainly due to duplication of gene segments. The collinearity between ZjCNGCs, OsCNGCs, and SjCNGCs suggests that CNGCs are evolutionarily conserved among gramineous plants. However, the Group III ZjCNGCs are only partially collinear with OsCNGCs and SjCNGCs, implying that the expansion of Group III ZjCNGC genes may have been an independent event occurring in Zoysia japonica. Protein interaction prediction revealed that ZjCNGCs, calcium-dependent protein kinase, H+-ATPase, outwardly rectifying potassium channel protein, and polyubiquitin 3 interact with ZjCNGCs. Multiple stress response regulatory elements, including those involved in salt stress, are present on the ZjCNGC promoter. The qPCR results revealed differences in the expression patterns of ZjCNGCs in different parts of the plant. Under salt stress conditions, the expression of ZjCNGCs was significantly upregulated in roots and leaves, with ZjCNGC8 and ZjCNGC13 showing the greatest increase in expression in the roots. These results collectively suggest that ZjCNGCs play an important role in salt tolerance and that their expansion into Group III may be a special mechanism underlying the salt tolerance of Zoysia japonica.