Enhanced Salt Tolerance Research Articles

Association Analysis Provides Insights into Molecular Evolution in Salt Tolerance during Tomato Domestication.

Salt stress impairs plant growth and development, generally resulting in crop failure. Tomato domestication gave rise to a dramatic decrease in salt tolerance caused by the genetic variability of the wild ancestors. However, the nature of artificial selection in reducing tomato salt tolerance remains unclear. Here, we generated and analyzed datasets on the survival rates and sodium (Na+) and potassium (K+) concentrations of hundreds of tomato varieties from wild ancestors to contemporary breeding accessions under high salinity. Genome-wide association studies (GWAS) revealed that natural variation in the promoter region of the putative K+ channel regulatory subunit-encoding gene KSB1 (potassium channel beta subunit in Solanum lycopersicum) is associated with survival rates and root Na+/K+ ratios in tomato under salt stress. This variation is deposited in tomato domestication sweeps and contributes to modified expression of KSB1 by salt-induced transcription factor SlHY5 in response to high salinity. We further found that KSB1 interacts with the K+ channel protein KSL1 to maintain cellular Na+ and K+ homeostasis, thus enhancing salt tolerance in tomato. Our findings reveal the crucial role of the SlHY5-KSB1-KSL1 module in regulating ion homeostasis and salt tolerance during tomato domestication, elucidating that selective pressure imposed by humans on the evolutionary process provides insights into further crop improvement.

Exploring the impact of rice husk biochar on oxidative mechanisms and salt stress tolerance in lettuce plants

Salt stress, which impairs plant growth and induces oxidative stress, presents a major challenge in agriculture. In response, biochar has emerged as a promising soil amendment, capable of enhancing plants’ stress tolerance mechanisms. This study investigated the impact of rice husk biochar (RBC), derived from rice husks, on enhancing salt stress tolerance in lettuce plants grown under greenhouse conditions. Molecular and chemical characterization of the biochar samples was performed using Scanning Electron Microscopy (SEM) and Raman spectroscopy. Salinity reduced the fresh and dry weights of the plants from 25.0 g plant−1 and 1.83 g plant−1 to 20.4 g plant−1 and 1.42 g plant−1, respectively. The application of RBC recovered the growth decline caused by salinity, increasing the fresh and dry weights of the plants to 28.1 g plant−1 and 1.83 g plant−1, respectively. While the concentrations of sodium and chloride in plants decreased with RBC application, potassium and silicon concentrations significantly increased. As a result of salt stress, hydrogen peroxide levels (H2O2) increased in plant tissues, and a decrease in H2O2 levels was observed with an increase in superoxide dismutase, catalase, and ascorbate peroxidase activities. Consequently, RBC proved to be effective in enhancing salt tolerance in lettuce plants. In conclusion, while RBC demonstrates significant potential for enhancing salt tolerance, its successful application depends on several factors such as biochar dosage, application method, soil type, and plant species, underscoring the need for further research to elucidate the mechanisms at play and optimize its use for sustainable soil management in saline conditions.

Exogenous Uniconazole promotes physiological metabolism and grain yield of rice under salt stress.

Salt stress severely inhibit plant growth and development. Uniconazole has been considered to significantly increase plant stress tolerance. However, the mechanism by which Uniconazole induces salt tolerance in rice seedlings and its impact on yield is still unclear. In this study, the effects of exogenous Uniconazole on morphogenesis, physiological metabolism, and yield of rice seedlings under salt stress were analyzed using the salt-tolerant rice variety HD961 and the salt-sensitive rice variety 9311. The results showed that salt stress significantly inhibited rice growth, disrupted the antioxidant system and pigment accumulation, and reduced photosynthesis, and yield. There were corresponding percent decreases of 13.0% and 24.1% in plant height, 31.6% and 55.8% in leaf area, 65.7% and 85.3% in root volume, respectively for HD961 and 9311. spraying However, compared to salt stress, the US treatment increased the percentage to 4.7% and 139.0% in root volume, 7.5% and 38.0% in total chlorophyll, 4.5% and 14.3% in peroxidase (POD) of leaves, 14.4% and 54.2% in POD of roots, 18.7% and 22.7% in catalase (CAT) of leaves, and 22.6% and 53.9% in CAT of roots, respectively, for HD961 and 9311. In addition, it also significantly enhanced photosynthesis at the reproductive stage, promoted the transport of carbohydrate to grains. And US treatment significantly increased the percentage to 9.0% in panicle length, 28.0% in panicle number per hole, 24.0% in filled grain number, 3.0% in 1000-grain weight, and 26.0% in yield per plant, respectively, for HD961, compared to salt stress. In summary, applying Uniconazole at the seedling stage can alleviate the damage induced by NaCl stress on rice by regulating the physiological metabolism of rice plants. This reduces the negative effects of salt stress, enhance salt tolerance, and boost rice production.

Exogenous Application of Selenium Nanoparticles (Se-NPs) to Mitigate Salt Stress in Soybean-Evaluation of Physiological, Molecular and Biochemical Processes

AbstractSalt stress is identified as a significant abiotic stress that hampers agricultural sustainability globally. The study was carried out to investigate the potential mitigating effects of selenium nanoparticles (Se-NPs) on salt stress in soybean. Two weeks old grown soybean seedlings were subjected to salt stress conditions (4000 mg L− 1 of sea salts). The plants were foliar sprayed with Se-NPs at concentrations of 0.0, 0.5, 1.0 and 1.5 mg L− 1 twice. The first application was applied at four weeks from sowing and the second application was added after two weeks from the first application. Compared to control, Se-NPs application mitigates the negative effect of salinity on plant growth to a variable extent. This improvement may be attributed to several factors such as increased the concentrations of photosynthetic pigments, total soluble sugars and total protein. In addition, Se-NPs alleviated the adversely effect of oxidative stress by increasing the antioxidant activities and potassium contents without markedly increase in the sodium content of the soybean leaf tissues. Also, Se-NPs enhanced the biosynthesis of secondary metabolites such as total phenolic content under salinity. Moreover, Se-NPs spray significantly reinforced the development of conducting secondary tissues in the leaves and roots of the treated plants. GmHKT1 gene transcription was markedly up-regulated in salinized soybean and foliar sprayed with Se-NPs as a molecular strategy to cope with the salinity. Based on the obtained results, among the different doses of Se-NPs, soybean plants sprayed with 1.0 mg L− 1 Se-NPs showed better salt tolerance. The foliar spray of Se-NPs may be considered as a promising approach to enhance salt tolerance in soybean plants, which could have significant implications for improving agricultural sustainability in salt-affected regions.

The MdCo gene encodes a putative 2OG-Fe (II) oxygenase that positively regulates salt tolerance in transgenic tomato and apple

Salinity stress is a significant environmental factor that impacts the growth, development, quality, and yield of crops. The 2OG-Fe (II) oxygenase family of enzyme proteins plays crucial roles in plant growth and stress responses. Previously, we identified and characterized MdCo, which encodes a putative 2OG-Fe (II) oxygenase, a key gene for controlling the columnar growth habit of apples. In this study, we explored the role of MdCo in salt stress tolerance. Expression analysis suggested that MdCo exhibits high expression in roots and is significantly induced by NaCl stress. Ectopic expression of MdCo exhibited enhanced salt stress tolerance in transgenic tomatoes, and these plants were characterized by better growth performance, and higher chlorophyll content, but lower electrolyte leakage and malondialdehyde (MDA), and less hydrogen peroxide (H2O2) and superoxide radicals (O2-) under salt stress. Overexpression of MdCo can effectively scavenge reactive oxygen species (ROS) by enhancing the activities of antioxidant enzymes and up-regulating the expression of stress-associated genes under salt stress, thereby enhancing salt tolerance in apple calli. Collectively, these findings provide new insights into the function of MdCo in salt stress tolerance as well as future potential application for apple breeding aimed at improving salt stress tolerance.

Fermentation broth of a novel endophytic fungus enhanced maize salt tolerance by regulating sugar metabolism and phytohormone biosynthesis or signaling

Soil salinization is a major environmental factor that severely affects global agriculture. Root endophytes can enter root cells, and offer various ecological benefits, such as promoting plant growth, improving soil conditions, and enhancing plant resistance. Su100 is a novel strain of endophytic fungus that was characterized from blueberry roots. In this study, we focused on evaluating the effects of Su100 secretion on maize growth. The results demonstrated that maize treated with Su100 fermentation broth (SFB) exhibited significantly stronger salt tolerance than the control. It is worth mentioning that the treated root system not only had an advantage in terms of biomass but also a change in root structure with a significant increase in lateral roots (LRs) compared to the control. Transcriptome analysis combined with hormone content measurements indicated that SFB upregulated the auxin signaling pathway, and also caused alterations in brassinosteroids (BR) and jasmonic acid (JA) biosynthesis and signaling pathways. Transcriptome analyses also indicated that SFB caused significant changes in the sugar metabolism of maize roots. The major changes included: enhancing the conversion and utilization of sucrose in roots; increasing carbon flow to uridine diphosphate glucose (UDPG), which acted as a precursor for producing more cell wall polysaccharides, mainly pectin and lignin; accelerating the tricarboxylic acid cycle, which were further supported by sugar content determinations. Taken together, our results indicated that the enhanced salt tolerance of maize treated with SFB was due to the modulation of sugar metabolism and phytohormone biosynthesis or signaling pathways. This study provided new insights into the mechanisms of action of endophytic fungi and highlighted the potential application of fungal preparations in agriculture.

Overexpression of rice lectin receptor-like kinase, OsLec-RLK, confers salinity stress tolerance and increases seed yield in pigeon pea (Cajanus cajan (L.) Millsp.).

OsLec-RLK overexpression enhances cell signalling and salt stress tolerance in pigeon pea, enhancing seed yield and harvest index and thus, enabling marginal lands to increase food and nutritional security. Lectin Receptor-like kinases (Lec-RLKs) are highly effective cell signaling molecules that counteract various stresses, including salt stress. We engineered pigeon pea by overexpressing OsLec-RLK gene for enhancing salt tolerance. The OsLec-RLK overexpression lines demonstrated superior performance under salt stress, from vegetative to reproductive phase, compared to wild types (WT). The overexpression lines had significantly higher K+/Na+ratio than WT exposed to 100mM NaCl. Under salt stress, transgenic lines showed higher levels of chlorophyll, proline, total soluble sugars, relative water content, and peroxidase and catalase activity than WT plants. Membrane injury index and lipid peroxidation were significantly reduced in transgenic lines. Analysis of phenological and yield attributes confirmed that the OsLec-RLK pigeon pea lines maintain plant vigor, with 10.34-fold increase in seed yield (per plant) and 4-5-fold increase in harvest index of overexpression lines, compared to wild type. Meanwhile, the overexpression ofOsLec-RLK up-regulated the expression levels ofhistone deacetylase1, acyl CoA, ascorbate peroxidase, peroxidase, glutathione reductase and catalase, which were involved in the K+/Na+homeostasis pathway. This study showed the potential of OsLec-RLK gene for increasing crop productivity and yields under salt stress and enabling the crops to be grown on marginal lands for increasing food and nutritional security.

The Physiological Mechanism of Exogenous Melatonin on Improving Seed Germination and the Seedling Growth of Red Clover (Trifolium pretense L.) under Salt Stress.

Salt stress can affect various physiological processes in plants, ultimately hindering their growth and development. Melatonin (MT) can effectively resist multiple abiotic stresses, improving plant stress resistance. To analyze the mechanism of exogenous MT to enhance salt tolerance in red clover, we conducted a comprehensive study to examine the influence of exogenous MT on various parameters, including seed germination indices, seedling morphological traits, and physiological and photosynthetic indicators, using four distinct red clover varieties (H1, H2, H3, and H4). This investigation was performed under various salt stress conditions with differing pH values, specifically utilizing NaCl, Na2SO4, NaHCO3, and Na2CO3 as the salt stressors. The results showed that MT solution immersion significantly improved the germination indicators of red clover seeds under salt stress. The foliar spraying of 50 μM and 25 μM MT solution significantly increased SOD activity (21-127%), POD activity, soluble sugar content, proline content (22-117%), chlorophyll content (2-66%), and the net photosynthetic rate. It reduced the MDA content (14-55%) and intercellular CO2 concentration of red clover seedlings under salt stress. Gray correlation analysis and the Mantel test further verified that MT is a key factor in enhancing seed germination and seedling growth of red clover under salt stress; the most significant improvement was observed for NaHCO3 stress. MT is demonstrated to improve the salt tolerance of red clover through a variety of mechanisms, including an increase in antioxidant enzyme activity, osmoregulation ability, and cell membrane stability. Additionally, it improves photosynthetic efficiency and plant architecture, promoting energy production, growth, and optimal resource allocation. These mechanisms function synergistically, enabling red clover to sustain normal growth and development under salt stress.

Role of Arbuscular Mycorrhizal Fungi in Alleviating Salinity Stress and Improving Physiological Parameters of Wheat (Triticum aestivum L.): A Review

Salinity stress poses a significant threat to global wheat production, impacting crop yield and food security. In recent years, Arbuscular Mycorrhizal Fungi (AMF) have gained attention as potential bioinoculants capable of mitigating salinity-induced stress and improving plant physiological parameters. This review provides a comprehensive examination of the role of AMF in alleviating salinity stress and enhancing physiological parameters in wheat (Triticum aestivum L.). Through a systematic analysis of relevant literature, we explore the mechanisms underlying the beneficial interactions between AMF and wheat under saline conditions. Key findings from various studies demonstrate that AMF colonization enhances wheat growth, nutrient uptake, and antioxidant enzyme activities, while reducing the adverse effects of salinity stress. However, challenges such as variability in AMF effectiveness and compatibility with modern agricultural practices persist. Future research directions should focus on refining AMF inoculation techniques and developing strains with enhanced salt tolerance to maximize their potential in sustainable agriculture. Overall, this review underscores the promising role of AMF in revolutionizing wheat cultivation in saline environments, offering insights for enhancing crop productivity and resilience to salinity stress.

Glycosylphosphatidylinositol-anchored lipid transfer proteins influence root cap cuticle formation at primary root tips, promoting NaCl tolerance in Arabidopsis seedlings.

Root cap cuticles (RCCs), comprising mainly very-long-chain fatty acids (VLCFAs), promote salt tolerance by preventing ion influx. Glycosylphosphatidylinositol-anchored lipid transfer protein (LTPG)1 and LTPG2 participate in VLCFA deposition in the extracellular region, aiding RCC formation in the lateral roots. In this study, we investigated whether LTPG1 and LTPG2 have similar functions in the primary roots of young Arabidopsis thaliana. Phenotypic analyses, fluorescence microscopy, and quantitative real-time reverse transcription polymerase chain reaction confirmed that NaCl exposure induced LTPG1 and LTPG2 expression and promoted RCC formation in young primary roots. The loss of RCC in the ltpg1 and ltpg2 mutants resulted in increased NaCl sensitivity of root elongation. NaCl also upregulated the expression of several NaCl-responsive genes in ltpg1 and ltpg2. We conclude that RCC formation via LTPG function is pivotal in enhancing salt tolerance in young primary roots.

OsRAV1 Regulates Seed Vigor and Salt Tolerance During Germination in Rice

Seed vigor is a complex trait encompassing seed germination, seedling emergence, growth, seed longevity, and stress tolerance, all are crucial for direct seeding in rice. Here, we report that the AP2/ERF transcription factor OsRAV1 (RELATED TO ABI3 AND VP1) positively regulates seed germination, vigor, and salt tolerance. Additionally, OsRAV1 was differently expressed in embryo and endosperm, with the OsRAV1 localized in the nucleus. Transcriptomic analysis revealed that OsRAV1 modulates seed vigor through plant hormone signal transduction and phenylpropanoid biosynthesis during germination. Haplotype analysis showed that rice varieties carrying Hap3 displayed enhanced salt tolerance during seed germination. These findings suggest that OsRAV1 is a potential target in breeding rice varieties with high seed vigor suitable for direct seeding cultivation.

Pan-genome analyses of 11 Fraxinus species provide insights into salt adaptation in ash trees

Ash trees (Fraxinus) exhibit rich genetic diversity and wide adaptation to various ecological environments, and several species are highly salt tolerant. Dissecting the genomic basis of salt adaptation in Fraxinus is vital for its resistance breeding. Here, we present 11 high-quality chromosome-level genome assemblies for Fraxinus species, which reveal two unequal subgenome compositions and two recent whole-genome triplication events in their evolutionary history. A Fraxinus pan-genome was constructed on the basis of structural variations and revealed that presence–absence variations (PAVs) of transmembrane transport genes have likely contributed to salt adaptation in Fraxinus. Through whole-genome resequencing of an F1 population from an interspecies cross of F. velutina ‘Lula 3’ (salt tolerant) with F. pennsylvanica ‘Lula 5’ (salt sensitive), we mapped salt-tolerance PAV-based quantitative trait loci (QTLs) and pinpointed two PAV-QTLs and candidate genes associated with Fraxinus salt tolerance. Mechanistically, FvbHLH85 enhances salt tolerance by mediating reactive oxygen species and Na+/K+ homeostasis, whereas FvSWEET5 enhances salt tolerance by mediating osmotic homeostasis. Collectively, these findings provide valuable genomic resources for Fraxinus salt-resistance breeding and the research community.

Elucidation of PGPR-responsive OsNAM2 regulates salt tolerance in Arabidopsis by AFP2 and SUS protein interaction

This study investigates the molecular mechanisms underlying salt stress responses in plants, focusing on the regulatory roles of OsNAM2, a gene influenced by the plant growth-promoting rhizobacterium Bacillus amyloliquefaciens (SN13). The study examines how SN13-modulated OsNAM2 enhances salt tolerance in Arabidopsis through physiological, biochemical, and molecular analyses. Overexpression of OsNAM2, especially with SN13 inoculation, improves germination, seedling growth, root length, and biomass under high NaCl concentrations compared to wild-type plants, indicating a synergistic effect. OsNAM2 overexpression enhances relative water content, reduces electrolyte leakage and malondialdehyde accumulation, and increases proline content, suggesting better membrane integrity and stress endurance. Furthermore, SN13 and OsNAM2 overexpression modulates essential metabolic genes involved in glycolysis, the pentose phosphate pathway, and the tricarboxylic acid cycle, facilitating metabolic adjustments crucial for salt stress adaptation. The interaction of OsNAM2 with SUS, facilitated by SN13, suggests enhanced sucrose metabolism efficiency, providing substrates for protective responses. Additionally, OsNAM2 plays a regulatory role in the ABA signaling pathway through significant protein-protein interactions like with AFP2. This study highlights the intricate interplay between SN13-responsive OsNAM2 and key signaling pathways, suggesting strategies for enhancing crop salt tolerance through targeted genetic and microbial interventions

Genome-wide identification of R2R3-MYB transcription factors in Betula platyphylla and functional analysis of BpMYB95 in salt tolerance

The Myeloblastosis (MYB) transcription factor (TF) family is one of the largest transcription factor families in plants and plays an important role in various physiological processes. At present, there are few reports on birch (Betula platyphylla Suk.) of R2R3-MYB-TFs, and most BpMYBs still need to be characterized. In this study, 111 R2R3-MYB-TFs with conserved R2 and R3 MYB domains were identified. Phylogenetic tree analysis showed that the MYB family members of Arabidopsis thaliana and birch were divided into 23 and 21 subgroups, respectively. The latter exhibited an uneven distribution across 14 chromosomes. There were five tandem duplication events and 17 segmental duplication events between BpMYBs, and repeat events play an important role in the expansion of the family. In addition, the promoter region of MYBs was rich in various cis-acting elements, and MYB-TFs were involved in plant growth and development, light responses, biotic stress, and abiotic stress. RNA-sequencing (RNA-seq) and quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) results revealed that most R2R3-MYB-TFs in birch responded to salt stress. In particular, the expression of BpMYBs in the S20 subfamily was significantly induced by salt, drought, abscisic acid, and methyl jasmonate stresses. Based on the weighted co-expression network analysis of physiological and RNA-seq data of birch under salt stress, a key MYB-TF BpMYB95 (BPChr12G24087), was identified in response to salt stress, and its expression level was induced by salt stress. BpMYB95 is a nuclear localization protein with transcriptional activation activity in yeast and overexpression of this gene significantly enhanced salt tolerance in Saccharomyces cerevisiae. The qRT-PCR and histochemical staining results showed that BpMYB95 exhibited the highest expression in the roots, young leaves, and petioles of birch plants. Overexpression of BpMYB95 significantly improved salt-induced browning and wilting symptoms in birch leaves and alleviated the degree of PSII photoinhibition caused by salt stress in birch seedlings. In conclusion, most R2R3-MYB-TFs found in birch were involved in the salt stress response mechanisms. Among these, BpMYB95 was a key regulatory factor that significantly enhanced salt tolerance in birch. The findings of this study provide valuable genetic resources for the development of salt-tolerant birch varieties.

Physiological and Transcriptomic Analyses Demonstrate the Ca2+-Mediated Alleviation of Salt Stress in Magnolia wufengensis.

Magnolia wufengensis, a newly discovered ornamental species in the Magnoliaceae family, is susceptible to salinity. Moreover, Ca2+ is an essential element for plant growth and is receiving increasing attention for its ability to mitigate the negative effects of environmental stress on plants. In the present study, we investigated the effect of Ca2+ on the growth and transcriptome of M. wufengensis under salt stress. The treatments used here were as follows: control, NaCl (150 mmol/L), CaCl2 (5 mmol/L), and NaCl (150 mmol/L) + CaCl2 (5 mmol/L). After a 60-day treatment period, plant growth indices were determined, and leaves were collected for physiological analysis and transcriptome investigation. The combined application of NaCl and CaCl2 alleviated phenotypic damage and restored seedling growth. Moreover, RNA sequencing data revealed that in the Na vs. control group and the NaCa vs. Na group, there were 968 and 2632 differentially expressed genes, respectively, which were both primarily enriched in secondary metabolism, glutathione metabolism, signaling hormone metabolism, glucose metabolism, and amino acid metabolism. These pathways were analyzed to screen key genes: the adenosine triphosphate (ATP)-binding cassette efflux transporter G1 (ABCG1) genes, which are related to transmembrane transport; the calmodulin genes, which are related to signal transmission; and the glutathione S-transferase (GST), glutathione peroxidase (GPX), and peroxidase (POD) genes related to antioxidant enzymes. Lastly, we constructed a hypothesis model of Ca2+-enhanced salt tolerance in M. wufengensis. This study reveals the potential mechanisms by which Ca2+ enhances the salt tolerance of M. wufengensis and provides a theoretical reference for its cultivation in saline areas.

Functional characterization of maize phytochrome-interacting factor 3 (ZmPIF3) in enhancing salt tolerance in arabidopsis

Soil salinization, a prevalent form of environmental stress, leads to significant soil desertification and impacts agricultural productivity by altering the internal soil environment, slowing cellular metabolism, and modifying cellular architecture. This results in a marked reduction in both the yield and diversity of crops. Maize, which is particularly susceptible to salt stress, serves as a critical model for studying these effects, making the elucidation of its molecular responses essential for crop improvement strategies. This study focuses on the phytochrome-interacting factor 3 (PIF3), previously known for its role in freezing tolerance, to assess its function in salt stress tolerance. Utilizing two transcript variants of maize ZmPIF3 (ZmPIF3.1 and ZmPIF3.2), we engineered Arabidopsis transgenic lines to overexpress these variants and analyzed their phenotypic, physiological, biochemical, and transcriptomic responses to salt stress. Our findings reveal that these transgenic lines displayed not only enhanced salt tolerance but also improved peroxide decomposition and reduced cellular membrane damage. Transcriptome analysis indicated significant roles of hormonal and Ca2+ signaling pathways, along with key transcription factors, in mediating the enhanced salt stress response. This research underscores a novel role for ZmPIF3 in plant salt stress tolerance, offering potential avenues for breeding salt-resistant crop varieties.

Enhanced salt tolerance in Glycyrrhiza uralensis Fisch. via Bacillus subtilis inoculation alters microbial community.

The widespread prevalence of saline environments poses a significant global environmental challenge. Salt stress, induced by saline soils, disrupts soil microecology and affects the plant-microbe-soil cycling process. Utilizing microbial fungicides stands as a primary strategy to mitigate salt stress-induced damage to plants and soils. This study investigated the influence of Bacillus subtilis (Bs) inoculation on the microbial community, assembly processes, and functional changes in bacteria and fungi in Glycyrrhiza uralensis Fisch. (licorice) seedlings under varying salt stress levels, primarily employing microbiomics techniques. Soil enzyme activities displayed a declining trend with increasing salt stress, which was mitigated by Bs inoculation. Microbiome analysis revealed a significant increase in bacterial and fungal operational taxonomic units, particularly in Ascomycetes and Nitrogen-fixing Bacteria, thereby enhancing soil denitrification. The abundance of Proteobacteria, Actinobacteriota, Bacteroidota, and Firmicutes in bacteria, as well as Ascomycota in fungi, increased with higher salt stress levels, a process facilitated by Bs inoculation. However, functional predictions indicated a reduction in the relative abundance of Dung Saprotrophs with Bs inoculation. Salt stress disrupted soil assembly processes, showcasing a continuous decline in diffusion limitation with increased salt concentration, where Bs inoculation reached a peak under moderate stress. In summary, this research elucidates the communication mechanism of Bs in enhancing salt tolerance in licorice from a microbiome perspective, contributing to a comprehensive understanding of abiotic and biotic factors.IMPORTANCELicorice is a herb that grows in deserts or saline soils. Enhancing the salt tolerance of licorice is necessary to maintain the quality of cultivated licorice and to ensure the supply of medicinal herbs. In the past, we have demonstrated the effectiveness of inoculation with Bacillus subtilis (Bs) to enhance the salt tolerance of licorice and revealed the key metabolic pathways for the development of salt tolerance through multi-omics. In this study, we used the microbiomics approach to reveal the plant-microbe-soil interactions at the level of inoculation of Bs affecting the dynamics of soil microbial communities from bacterial and fungal perspectives, thus bridging the interactions between biotic and abiotic factors.

Integrative Analyses Reveal the Physiological and Molecular Role of Prohexadione Calcium in Regulating Salt Tolerance in Rice.

Salinity stress severely restricts rice growth. Prohexadione calcium (Pro-Ca) modulation can effectively alleviate salt stress in rice. In this study, we explored the effects of Pro-Ca on enhancing salt tolerance in two rice varieties, IR29 and HD96-1. The results revealed that Pro-Ca markedly enhanced root and shoot morphological traits and improved plant biomass under salt stress. Chlorophyll a and b content were significantly increased, which improved photosynthetic capacity. Transcriptomic and metabolomic data showed that Pro-Ca significantly up-regulated the expression of genes involved in E3 ubiquitin ligases in IR29 and HD96-1 by 2.5-fold and 3-fold, respectively, thereby maintaining Na+ and K+ homeostasis by reducing Na+. Moreover, Pro-Ca treatment significantly down-regulated the expression of Lhcb1, Lhcb2, Lhcb3, Lhcb5, and Lhcb6 in IR29 under salt stress, which led to an increase in photosynthetic efficiency. Furthermore, salt stress + Pro-Ca significantly increased the A-AAR of IR29 and HD96-1 by 2.9-fold and 2.5-fold, respectively, and inhibited endogenous cytokinin synthesis and signal transduction, which promoted root growth. The current findings suggested that Pro-Ca effectively alleviated the harmful effects of salt stress on rice by maintaining abscisic acid content and by promoting oxylipin synthesis. This study provides a molecular basis for Pro-Ca to alleviate salt stress in rice.

Editing and genome-wide analysis upstream open reading frames contributes to enhancing salt tolerance in tomato.

The salinization of soil constitutes a substantial hindrance to the advancement of sustainable agriculture. Our research seeks to elucidate the role of a Rab GTPase-activating protein (RabGAP) family member, SlRabGAP22, in salt tolerance and its translational regulation under salt stress in tomatoes, employing gene-editing techniques and ribosome profiling methodologies. Findings demonstrate that SlRabGAP22 acts as a positive regulator of tomato salt tolerance, with four predicted upstream open reading frames (uORFs) classified into three categories. Functional uORFs were found to be negative regulation. Editing these uORFs along with altering their classifications and characteristics mitigated the inhibitory effects on primary ORFs and fine-tuned gene expression. Enhanced tomato salt tolerance was attributed to improved scavenging of reactive oxygen species, reduced toxicity Na+, and diminished osmotic stress effects. Furthermore, we conducted genome-wide analysis of ORFs to lay the foundation for further research on uORFs in tomatoes. In summary, our findings offer novel perspectives and important data for the enhancement of genetic traits via uORF-based strategies and translational regulation against the backdrop of salt stress.

Strategies for Achieving High and Sustainable Plant Productivity in Saline Soil Conditions

The accumulation of salt in arable lands is a source of significant abiotic stress, contributing to a 10% decline in the world’s total arable lands and threatening food productivity and the sustainability of agriculture. About 76 million hectares of productive land are estimated to have been affected by human-induced salinization such as extreme salt deposits in soil, which are mainly caused by the actions of humans. For instance, continued irrigation and the frequent use of chemical fertilizers need to be understood. To ensure food availability, it is essential to improve upon traditional farming methods using current technologies to facilitate the reclamation of saline-affected arable lands to achieve high and sustainable food production. This review details current innovative strategies such as the modification of metabolic pathways, manipulation of antioxidant pathways, genetic engineering, RNA interference technology, engineered nanoparticles, arbuscular mycorrhizal fungi (AMF), organic amendments, and trace elements for improving saline marginal lands. These strategies were identified to have contributed to the improvement of plants salinity tolerance in diverse ways. For instance, the accumulation of plant metabolites such as amino acids, sugars, polyols, organic acids, saponins, anthocyanins, polyphenols, and tannins detoxify plants and play crucial roles in mitigating the detrimental effects of oxidative damage posed by salinity stress. Multiple plant miRNAs encoding the up- and down-regulation of single- and multi-ion transporters have been engineered in plant species to enhance salt tolerance. Nanomaterials and plant root system colonized by arbuscular mycorrhizal increase water uptake, photosynthetic efficiency, and biomass allocation in plants exposed to saline stress by excluding 65 percent of the Na+ uptake and enhancing K+ uptake by 84.21 percent. Organic amendments and trace elements reduced salinity concentrations by 22 percent and improved growth by up to 84 percent in maize subjected to salinity stress. This study also discusses how researchers can use these strategies to improve plants growth, development, and survival in saline soil conditions to enhance the productivity and sustainability of agriculture. The strategies discussed in this study have also proven to be promising approaches for developing salinity stress tolerance strategies for plants to increase agricultural productivity and sustainability.