Search Results (278)

Soil salinization severely constrains plant growth and agricultural productivity. Identifying key genes conferring alkali tolerance and elucidating their regulatory mechanisms is of great significance for breeding salt–alkali-tolerant leguminous crops. In this study, we investigated the soybean genes GmCML27 and its potential interacting partner GmU2AFb, and explored their functions in response to alkali stress in narrow-leaf lupine (Lupinus angustifolius) through bioinformatics analyses. Protein interaction prediction and experimental validation further supported a potential association between GmCML27 and GmU2AFb. Using an Agrobacterium rhizogenes (A. rhizogenes)-mediated hairy root transformation system, composite plants carrying empty vector (CK), GmCML27-overexpression construct (GC), GmU2AFb-overexpression construct (GU), or both GmCML27 and GmU2AFb overexpression constructs (GCU) were generated and evaluated under NaHCO₃-induced alkali stress. The results showed that all transformed composite plants exhibited enhanced alkali tolerance, with the GCU plants displaying the strongest phenotype. Compared with CK plants, transformed composite plants maintained higher catalase (CAT) activity, proline (Pro) content, and root vitality, while accumulating lower levels of reactive oxygen species (ROS) and malondialdehyde (MDA), and retaining more intact root architecture. Furthermore, the expression levels of alkali tolerance-related genes, including LaMYB39, LaSOS1, LaNHX6, LaKIN, LaDnaJ1, and LaP5CS, were significantly upregulated in transgenic lines. Collectively, our findings demonstrate that both GmCML27 and GmU2AFb positively regulate alkali tolerance in lupine, and their co-expression confers enhanced alkali tolerance compared with single-gene overexpression. These two genes may jointly contribute to alkali stress adaptation through regulation of antioxidant capacity and stress-responsive pathways. This study highlights the potential roles of GmCML27 and GmU2AFb in lupine responses to alkali stress and provides candidate gene resources for future improvement of lupine alkali tolerance. Full article

Soil salinization critically restricts melon production, and the seed germination stage is particularly vulnerable to saline–alkali stress (SAS). Although silicon (Si) is known to enhance plant stress tolerance, its role in alleviating SAS-induced inhibition of melon seed germination—particularly under combined neutral and alkaline salt stress—remains insufficiently characterized. Here, using the melon cultivar ‘Xinyinhui’, we simulated SAS with a mixture of NaCl and NaHCO₃ and screened for the optimal Si concentration. We then systematically examined physiological, biochemical, and gene expression responses. SAS significantly inhibited germination (20.4% reduction in germination rate; 56.9% in vigor index) and induced oxidative damage (MDA increased by 9.7%; superoxide anion by 170.6%), suppressed antioxidant enzyme activities (SOD −28.8%, POD −69.4%), and disturbed starch metabolism. Exogenous Si at 1.25 mmol·L⁻¹ effectively alleviated these effects: The germination rate increased from 71.7% to 88.8%, and SOD and POD activities increased by 26.7% and 63.6%, while MDA and superoxide anion decreased by 7.1% and 16.4%. Si also promoted starch degradation, as indicated by a 13.9% reduction in starch content, 8.4% increase in total amylase activity, and 23.2% upregulation of CmBMY expression. In addition, Si significantly improved root morphology: Root surface area, volume, branch number, and tip number increased by 19.8–326.3%, while the average root diameter decreased by 24.4%. These results suggest that exogenous Si alleviates SAS inhibition of melon seed germination through coordinated regulation of antioxidant defense and starch metabolism rather than through a single pathway. Our findings provide a physiological basis for the potential application of Si fertilizer in melon cultivation under saline–alkali conditions. Full article

Background: Peanuts (Arachis hypogaea L.) cultivated in saline-alkali areas frequently endure drought stress. Yet, mechanistic research on combined salt–drought stress for peanut growth and yield remains scarce. Methods: A pot culture experiment was conducted to investigate the impacts of short-term drought imposed at the flowering stage on peanuts grown in saline-alkali soil. We comprehensively assessed peanut agronomic traits, cell ultrastructure, physicochemical properties, hormone change, rhizobacterial community, and rhizosphere soil metabolic profiles between single salt stress and salt and drought co-stress. Results: Our study reveals that co-stress markedly suppressed peanut yield, with 100-pod weight, 100-seed weight, pods per plant, and pod yield per plant reduced by 3.16%, 12.79%, 16.65%, and 22.14% relative to salt-only treatment. Combined stress triggered more severe ultrastructural alterations, cell wall degradation, and tissue deformation. It also degraded soil quality by lowering available phosphorus, alkaline hydrolyzable nitrogen, and available potassium. Meanwhile, co-stress reduced the relative abundance of nitrogen-cycling and plant growth-promoting rhizobacteria, alongside depleted beneficial sugar metabolites in rhizosphere soil. These shifts jointly constrain peanut growth and productivity. Conclusions: Thus, it is imperative to implement timely irrigation practices to avoid drought during peanut cultivation in saline-alkali areas, particularly during the flowering stage. Full article

Aiming at severe soil secondary salinization, poor water retention and insufficient salt tolerance of conventional acrylic-based modifiers in arid and semi-arid regions of China, a poly(ethylene glycol) maleate citrate (PEGMC) crosslinking monomer was synthesized through esterification, and a dual covalent–hydrogen crosslinked P(PEGMC/AA) hydrogel was fabricated via free radical copolymerization with acrylic acid (AA). The hydrogel was characterized by NMR, FTIR, SEM, TGA and elemental mapping, while its binding mechanism with saline–alkali ions was elucidated through DFT calculations and molecular dynamics simulations. Its amelioration performance was evaluated through swelling, soil water retention, desalination and pot germination experiments. The hydrogel exhibited outstanding water absorbency, salt resistance and dry–wet cycling stability, with swelling ratios of 712 g/g in deionized water and 285 g/g in 0.9% NaCl solution, and remained 200 g/g after four dry–wet cycles. It enhanced soil water retention remarkably (over 93% after 72 h). At 0.30% dosage, soil salt content declined from 7.1 g/kg to 1.3 g/kg with desalination efficiency exceeding 80%, owing to porous physical adsorption and chemical chelation toward Na⁺, Ca²⁺ and Mg²⁺, with a binding energy of −136.936 kJ/mol. Pot tests revealed that crop germination rate rose from 19% (blank) to 75% under severe saline–alkali stress. Meanwhile, the hydrogel inhibited nutrient leaching and favored soil-water conservation. This work first incorporated PEGMC monomer into agricultural hydrogels to construct a stable dual crosslinked network, clarifying its synergistic mechanisms for salt fixation and water retention macroscopically and microscopically. It provides a promising functional material and theoretical basis for green, efficient in situ amelioration of dryland saline–alkali soil. Full article

Soil salinization represents one of the most severe abiotic constraints on global forest productivity. Populus, the most widely cultivated fast-growing timber tree and a premier model woody plant, exhibits striking intrageneric variation in salt tolerance—from the extremely halophytic Populus euphratica to highly salt-sensitive cultivated clones. Understanding the molecular basis of this variation has profound implications for saline–alkali land reclamation and salt-tolerant variety breeding. This review systematically synthesizes current knowledge on Populus salt-stress responses, covering three primary injury mechanisms (osmotic stress, ionic toxicity, and oxidative damage) and the corresponding physiological countermeasures. We further survey functional genes across four major categories: ion transporters, osmotic-adjustment enzymes, antioxidant-defense components, and transcription factors. Crucially, we extend beyond the herbaceous-plant paradigm by examining salt-tolerance strategies that are specific to the woody architecture of Populus: long-distance radial and axial Na⁺ transport through tall stems, salt sequestration in senescent bark and wood parenchyma, and deep-root ion exclusion strategies. Comparative insights from other woody genera are incorporated to highlight convergent and divergent mechanisms. On this basis, we propose an integrated multi-level regulatory model in which Na⁺ compartmentalization/efflux serves as the core, ROS homeostasis as the key regulatory axis, and osmotic adjustment as the auxiliary strategy. Outstanding challenges—including unresolved primary salt-signal perception, insufficient pathway integration, and limited in planta gene-function verification—are critically assessed, and future research priorities encompassing multi-omics integration, CRISPR-based gene editing, and natural-population genomics are outlined. Full article

Calcium alginate is an anionic polysaccharide that forms an ionically crosslinked hydrogel network with encapsulation properties to nucleic acids and nutrients for the amelioration of osmotic stress, ion toxicity and nutrient imbalance in saline–alkali soils. Traditional soil reclamation methods, including salt leaching, incorporation of organic matter, and gypsum application, are water-intensive under a changing climate, ultimately necessitating transformative bio-based solutions for food security. Calcium alginate-based biohydrogel represents a versatile platform with a tunable macromolecular architecture, ionic crosslinking via an “egg box” mechanism and potentially promising to deliver engineered co-encapsulated nutrients and genetically modified cargoes. The mannuronic (M) and guluronic (G) acid (M/G) ratios govern ion exchange capacity, rheological behavior and release kinetics in saline- and alkali-stressed environments. Recent studies on alginate-based nutrient encapsulation showed reduced oxidative damage and a 15–50% increase in plant-available water. The irrigation intervals extended from 7 to 14 days and yield gains by 24% in wheat, with comparable improvements in maize, tomato, rice and cotton. Calcium alginate hydrogels encapsulated salt tolerance genes (HKT1, SOS1, AVP1) encoding proteins mainly involved in Na⁺ retrieval from xylem, Na⁺ extrusion from root cells and vacuolar Na⁺ sequestration, which have achieved yield gains of 40 to 75% across wheat, rice and maize. Future research should focus on optimizing mechanical strength, crosslinking chemistry and smart bioencapsulation strategies for sustainable development so that crops are capable of withstanding variable climate stresses. Full article

Salt stress severely restricts plant growth and reduces crop yield. Strigolactones (SLs) are carotenoid-derived phytohormones involved in the regulation of plant salt tolerance. Salt stress can modulate the expression of SL biosynthetic and signaling genes, thereby affecting SL accumulation and signaling responses. SLs also interact with abscisic acid (ABA), reactive oxygen species (ROS), and other signaling molecules to coordinate downstream stress responses. At the physiological level, SLs alleviate salt stress by maintaining Na⁺/K⁺ homeostasis, enhancing osmotic adjustment and antioxidant defense, and reducing damage to the photosynthetic system. In addition, SLs can enhance plant resource acquisition and adaptive capacity under salt stress by regulating root architecture and promoting hyphal branching of arbuscular mycorrhizal fungi (AMF). This review focuses on SL-mediated regulation of plant salt tolerance at the molecular and physiological levels and further summarizes exogenous SL application strategies for alleviating salt stress, as well as research progress on key genes in the SL pathway for the genetic improvement of salt tolerance. Clarifying the potential of SLs in regulating plant responses to salt stress could provide new insights into sustainable crop production in saline-alkali environments. Full article

The accumulation of polylactic acid nano-plastics (PLA-NPs) in saline–alkali soils poses a potential threat to crop growth; however, the underlying toxicological mechanisms remain poorly understood. We conducted a hydroponic experiment to investigate the effects of polylactic acid (PLA) NPs (100 and 500 mg L⁻¹) under conditions both in the presence (50 mmol L⁻¹ NaCl) and absence of salt stress on maize seed germination, seedling growth, physiological characteristics, and transcriptomic responses. The results showed that exposure to PLA-NPs, particularly at a high concentration (500 mg L⁻¹), significantly inhibited seed germination and seedling growth. Compared to the low concentration (100 mg L⁻¹) of PLA-NPs, the high concentrations (500 mg L⁻¹) reduced the germination percentage by 25.0% and fresh weight by 25.8% and increased root MDA (6.7%), SOD (30.0%), POD (6.3%), ASA (13.4%), and GSH (13.1%). Under the same concentration of the PLA, PLA + NaCl treatments exerted stronger inhibitory effects than PLA-NPs alone, with the seed germination percentage and fresh weight reduced by an average of 52.7% and 6.6%, respectively. Notably, the inhibitory effects and integrated biomarker response (IBR) index of the PLA 500 + NaCl treatment were the highest. The presence of PLA-NPs in roots was confirmed using confocal laser scanning microscopy. GO enrichment analysis showed that pathways related to nutrient reservoir activity, oxidoreductase activity, hydrogen peroxide catabolic process, and hydrogen peroxide metabolic process were enriched under PLA-NP and PLA + NaCl treatments. KEGG analysis further indicated enrichment in phenylpropanoid biosynthesis, ABC transporters, and alpha-linolenic acid metabolism. The PLA-NP and PLA + NaCl treatments upregulated genes associated with oxidoreductase activity (Zm00001eb238800, Zm00001eb128620, and Zm00001eb020790). These findings suggest that synergistic toxicity of PLA-NPs and salinity stress in maize is primarily driven by the internalization of PLA-NPs and Na⁺ within maize roots, which negatively impacts maize seed germination and seedling growth by disrupting redox homeostasis and metabolic balance, thereby forcing plants to reallocate resources from growth toward oxidative stress defense. This study provides critical insights into the environmental risks of biodegradable nano-plastics in saline–alkali soil environments. Full article

Thinopyrum ponticum, a salt-tolerant grass widely used in the restoration of saline–alkali lands, was the focus of this study. Two accessions with contrasting salt tolerance—‘4–6’ (salt tolerant) and ‘5–22’ (salt sensitive)—were watered with 500 mM NaCl solution for 14 days, and seedling growth and physiological responses were assessed. Salt stress significantly inhibited the growth of both accessions, but ‘4–6’ was less impacted. Morphologically, ‘4–6’ adapted to stress by increasing the root-to-shoot ratio, increasing leaf length, and decreasing leaf width. In contrast, the growth of ‘5–22’ was comprehensively inhibited, with significant reductions in fresh weight, dry weight, leaf length, and leaf area. Physiologically, the contents of malondialdehyde and proline increased in both accessions, but ‘4–6’ exhibited stronger antioxidant capacity and more flexible regulation of sugar metabolism (with sucrose decreasing while fructose and glucose increased) to maintain osmotic balance. In comparison, ‘5–22’ showed dysregulated sugar metabolism, characterized by sucrose accumulation and a decrease in fructose, which exacerbated salt damage. Regarding hormones under salt stress, IAA content increased in leaves of ‘4–6’ but decreased in ‘5–22’. Jasmonate-related hormones decreased in both accessions; however, ‘4–6’ maintained higher basal levels and smaller reductions, indicating stronger hormonal regulation capacity. Correlation analysis confirmed that IAA- and JA-related hormones play important roles in salt tolerance of Thinopyrum ponticum. In terms of ion balance, ‘4–6’ maintained higher K⁺/Na⁺ and Ca²⁺/Na⁺ ratios, promoted beneficial cation transport to shoots, and restricted Cl⁻ accumulation. In contrast, ‘5–22’ suffered from disrupted ion balance and excessive Cl⁻ accumulation, resulting in severe growth inhibition. In addition, the key indicators screened by RDA provide an important reference for revealing the salt tolerance mechanism of Thinopyrum ponticum and for constructing a corresponding evaluation system. This study elucidates the mechanisms underlying differential salt tolerance among Thinopyrum ponticum accessions, highlighting the coordinated role of hormonal reprogramming and ion homeostasis. These findings offer both theoretical insights and practical guidance for breeding new salt-tolerant varieties of Thinopyrum ponticum and for the amelioration of saline–alkali lands. Full article

Soil salinization severely constrains plant growth, yet the roles of ion composition and rhizosphere microbial communities in shaping plant performance remain poorly resolved. Here, we investigated multiple crop and wild plant species in saline–alkali soils and compared rhizosphere ion composition, microbial communities, and plant growth status. Restricted plant growth was consistently associated with elevated Na⁺ and Cl⁻ concentrations, while fungal diversity was significantly higher in well-growing plants. Ion composition (particularly Na⁺, Cl⁻, SO₄^2–, and Mg²⁺) was strongly correlated with microbial community structure, and a set of microbial taxa, including bacterial phyla such as Deinococcota and Gemmatimonadota and fungal phyla within Ascomycota and Basidiomycota, were repeatedly associated with plant growth status across species. Notably, plant species exhibited distinct apparent, threshold-like responses, and in several cases, plant growth differences were not fully explained by salinity levels alone, suggesting that rhizosphere microbial communities may buffer salt stress. Together, our results reveal that ion composition governs plant growth not only through direct ionic stress but also via microbially mediated pathways, highlighting an ion–microbe–plant interaction framework underlying growth variation in saline–alkali soils. Full article

Soil depth and habitat degradation can reshape fungal communities in salt-affected wetlands, but their effects on fungal ecological processes remain insufficiently understood. This study examined soil fungi in the Halahai Provincial Nature Reserve and adjacent converted farmland in the western Songnen Plain, Northeast China, where salt-affected meadow soils correspond mainly to Solonetz. Four habitat types—reed wetland, meadow steppe, degraded Suaeda saline patch, and converted farmland—were sampled at 0–20 cm and 20–40 cm soil depths. Soil properties, fungal diversity, taxonomic composition, environmental associations, niche breadth, assembly processes, and FUNGuild-based trophic modes were analyzed using ITS sequencing. Degraded Suaeda soils showed the strongest salinity–alkalinity stress, with pH values of 10.34–10.30 and electrical conductivity of 1.70–1.75 dS·m⁻¹. Fungal richness was highest in surface-converted farmland, with a Sobs value of 423.33, and lowest in deeper degraded Suaeda soil, with a Sobs value of 86.00. Ascomycota dominated most groups, especially degraded Suaeda soils, where its relative abundance reached 75.29–76.80%. ANOSIM confirmed significant community dissimilarity among habitat-depth groups (R = 0.56878, p = 0.001). Specialists accounted for 68.07% of fungal taxa, and stochastic processes, especially drift and dispersal limitation, contributed substantially to assembly. These results indicate that soil depth, salinity–alkalinity, and habitat conversion jointly regulate fungal community structure and ecological processes in degraded soda saline–alkali wetlands. Full article

In this study, nine strains of plant growth-promoting rhizobacteria (PGPR) with multiple growth-promoting functions were isolated and screened from the rhizosphere of plants (Phragmites communis, Triglochin maritimum, and Alhagi maurorum) in the arid and barren regions of Western China. These strains belong to five genera: Klebsiella, Bacillus, Serratia, Pseudomonas, and Flavobacterium. The growth-promoting characteristics of these nine strains (PAP4, PA35, AC12, ACP1, AC25, TP7, TP8, TP12, and TP14) were analyzed. Furthermore, the growth-promoting potential of these PGPR strains was comprehensively evaluated through plate and pot experiments using Arabidopsis thaliana and alfalfa. The results indicate that most strains possess the ability to fix nitrogen and secrete zeatin and extracellular polysaccharides (EPS). Some strains exhibited significant traits such as phosphate solubilization, siderophore secretion, and the production of 1-aminocyclopropane-1-carboxylate (ACC) deaminase and indole-3-acetic acid (IAA). All strains showed high salt tolerance (0–8% NaCl) and were induced to secrete more EPS under salt stress. Plate experiments demonstrated that volatile organic compounds (VOCs) from the nine strains significantly promoted the root development of Arabidopsis thaliana and optimized its root architecture. Pot experiments revealed that inoculation with single strains influenced the growth of alfalfa to varying degrees; among them, strain TP14 showed the best performance, increasing plant height and shoot dry weight by 44.7% and 51.2%, respectively. Regarding microbial consortia, the combinations BD (PAP4 + TP14), ABC (PA35 + PAP4 + AC25), and ABCD (PA35 + PAP4 + AC25 + TP14) significantly improved the biomass, plant height, and stem diameter of alfalfa. The superior strains and their combinations identified in this study effectively promote plant growth. These high-performing PGPR strains provide valuable microbial resources for the development of bio-fertilizers tailored for saline–alkali and barren regions in Western China. Full article

Global crop production faces serious threats from soil salinization. Microbial resources are often exploited to be used as fertilizers or seed coatings to address this issue. Parametarhizium changbaiense, as a novel beneficial microorganism, has been discovered to be capable of assisting limited crops such as mung bean in resisting salt–alkali stress. To investigate the effects of P. changbaiense on sugar beet under salt–alkali stress, the salt (NaCl:Na₂SO₄, molar ratio 9:1) and alkali (NaHCO₃:Na₂CO₃, molar ratio 9:1) stress were set on sugar beet germplasm 780016B. Results demonstrated that P. changbaiense improved the phenotypic characteristics of sugar beet seedlings under salt–alkali stress. The biomass parameters such as plant height and fresh weight significantly increased by growth-promoting effect. The elevated antioxidant enzyme activity could help protect plants from ROS damage induced by stress. Relative electrical conductivity and MDA content decreased with inoculation, thereby mitigating membrane lipid peroxidation and improving membrane system stability. The higher content of soluble sugar could maintain cell turgor pressure and alleviate osmotic stress. Inoculation with P. changbaiense enhanced chlorophyll content, fluorescence, and photosynthetic capacity. The more superior root vitality and architecture were suitable for the functions of metabolism and absorption. P. changbaiense could promote the growth and physiological characteristics under salt–alkali stress, so it has practical application value in agricultural production. Full article

Drought and soil salinization severely limit the productivity of global agriculture and forestry, highlighting the urgency of identifying stress-resistant genes for molecular breeding. B-box (BBX) proteins constitute a class of zinc finger transcription factors that play significant roles in plant abiotic stress responses. Amorpha fruticosa (A. fruticosa) is a perennial woody plant with exceptional adaptability to harsh environments, serving as a valuable resource for mining stress-resistant genes. In this study, the AfBBX gene was cloned from A. fruticosa, and its function in stress tolerance was systematically analyzed. Bioinformatics analysis confirmed that AfBBX contains a conserved ZnF-BBOX domain and shares functional conservation with the BBX protein family. Quantitative real-time polymerase chain reaction (qRT-PCR) revealed tissue-specific expression of AfBBX, with the highest expression in stems and the lowest in young leaves. Furthermore, AfBBX expression was dynamically regulated in roots and leaves of A. fruticosa under treatments of 5 μM ABA (drought mimic), H₂O₂ (oxidative stress), 10% PEG600 (osmotic stress), and NaHCO₃ (alkaline stress). Transgenic tobacco lines overexpressing AfBBX showed enhanced tolerance to osmotic and salt–alkali stresses at both germination and seedling stages. Meanwhile, compared to wild-type (WT) tobacco, transgenic lines exhibited higher germination rates, longer root lengths, and greater fresh weights under stress conditions. Under natural drought and salt–alkali stresses, transgenic tobacco maintained higher chlorophyll fluorescence intensity (Fv/Fm values), elevated activities of antioxidant enzymes [superoxide dismutase (SOD)], and reduced malondialdehyde (MDA) content. In conclusion, AfBBX enhances stress tolerance by mitigating photosystem damage, increasing reactive oxygen species (ROS) scavenging capacity, and reducing membrane lipid peroxidation. The findings from this study provide novel insights into the molecular mechanism underlying AfBBX-mediated stress resistance and offer valuable genetic resources for breeding drought- and salt-tolerant crops and forest trees. Full article

According to an FAO report, the total area of saline-alkali land worldwide is approximately 954 million hectares, accounting for about 20% of global cultivated land. Saline-alkali stress significantly reduces soybean (Glycine max L.) yield and quality, and saline-alkali-tolerant plant growth-promoting bacteria (PGPB) have shown important application value for soybean planting in such farmlands. In this study, 15 strains of saline-alkali-tolerant bacteria were isolated from saline-alkali soil in Anda City, Heilongjiang Province, China, and identified morphologically, belonging to the genera Enterobacter, Bacillus, Chryseobacterium, Acinetobacter, Enterococcus, and Pseudomonas. Through tests for nitrogen fixation, phosphorus solubilization, potassium solubilization, hydrolase production (including pectinase, amylase, and protease), and germination promotion assays, Bacillus pumilus AD14 was identified as having the best growth-promoting effect on soybean seedlings. Pot experiments in saline-alkali soil showed that AD14 significantly promoted soybean seedling growth, increasing plant height by 5.63–6.37 cm and root length by 3.58–3.99 cm compared to the control. AD14 also enhanced saline-alkali tolerance by improving the activity of antioxidant enzymes including superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) and increasing soluble sugar and protein contents. Meanwhile, soil pH decreased by 10.94–12.15% and soluble salt content decreased by 9.59–13.39% after planting, and soil enzyme activities (including urease, sucrase, and catalase) increased markedly. These results demonstrate the great potential of AD14 for soybean planting in saline-alkali soil. This study provides a relevant reference for enriching the resources of saline-alkali-tolerant PGPB and developing new biological agents suitable for soybean planting in saline-alkali soils. Full article