Plant salt response: Perception, signaling, and tolerance

Competitive ion uptake and transcriptional regulation as a coordinated dual mechanism of NaCl-mediated cadmium detoxification in Suaeda salsa

Cadmium (Cd), a highly toxic heavy metal, severely inhibits plant growth. Salt alleviates Cd stress in halophytes, however, the molecular mechanisms governing salt-mediated regulation of Cd toxicity remain poorly understood. This study elucidates the protective mechanism of NaCl in Cd-stressed Suaeda salsa seedlings. Cd exposure suppressed seedling growth and induced membrane lipid peroxidation. Conversely, NaCl application not only maintained normal growth but also effectively ameliorated Cd-induced phytotoxicity, potentially through osmotic adjustment mechanisms. Notably, using ion flux analysis, we found that NaCl attenuated Cd2+ influx into root epidermal cells, thereby enhancing Cd resistance. Pharmacological inhibition studies confirmed that Na + competitively inhibits Cd2+ uptake through shared channels/transporters. Furthermore, RT-qPCR gene expression profiling revealed that NaCl coordinately activated both ionic compartmentalization and efflux systems through upregulating plasma membrane-localized SsSOS1 and tonoplast-associated SsNHX1 for Na + extrusion and vacuolar sequestration, enhancing Cd2+ compartmentalization via SsCAX and SsVHA-B mediated transport and maintaining cellular homeostasis through SsHKT1 and SsPIP-mediated regulation of water and K+ balance, or indirectly inhibit Cd2+ influx. It reveals that salt weakens Cd2+ influx and enhances Cd tolerance by activating a coordinated gene regulatory network in Suaeda salsa. This finding offers valuable insights into phytoremediation strategies for enhancing crop resilience in Cd-contaminated saline soils.

Root Transcriptome Analysis Identifies Salt-Tolerance Genes in Sweet Corn Chromosome Segment Substitution Lines (CSSLs)

Salt stress severely constrains global crop productivity. However, most sweet corn cultivars exhibit weak tolerance to salt stress. In this study, two sweet corn CSSLs, salt-tolerant line D55 and salt-sensitive line D96, were selected as materials. We conducted comparative phenotyping and physiological profiling of seedlings under salinity treatment, and transcriptome analysis was carried out by sampling root tissues at 0 h, 4 h, 12 h, and 72 h post-treatment. The results indicated that D55 exhibited enhanced seedling height, root length, fresh weight, relative chlorophyll content, and antioxidant enzyme activities, while showing reduced malondialdehyde accumulation in comparison to D96. Pairwise comparisons across time points (0 h, 4 h, 12 h, 72 h) identified 6317 and 6828 differentially expressed genes (DEGs) in D55 and D96. A total of 49 shared DEGs across four time points were identified in D55 and D96, which were enriched in 12 significant Gene Ontology (GO) terms. Only eight DEGs were shared between genotypes across all comparisons. Transcriptomic analysis revealed 1281, 1946, and 1717 DEGs in genotypes D55 and D96 at 4 h, 12 h, and 72 h post-salt treatment, respectively. Genes associated with reactive oxygen species (ROS) homeostasis, phenylpropanoid metabolism, cutin, suberin and wax biosynthesis, and benzoxazinoid synthesis exhibit enhanced sensitivity in the salt-tolerant genotype D55. This leads to an enhanced ROS scavenging capacity and the establishment of a multi-layered defense mechanism. Additionally, brassinosteroid (BR), gibberellin (GA), and abscisic acid (ABA) and auxin-related genes exhibited different responses to salt stress in sweet corn. A hypothetical model, which established a multi-layered salt adaptation strategy, by integrating ROS detoxification, osmotic balance, and phytohormone signaling, was put forward. By integrating transcriptome and differential chromosomal fragment data, our findings identify 14 candidate genes for salt tolerance, providing potential ideal target genes in breeding to improve salt tolerance in sweet corn.

Silicon-induced mitigation of salt stress in GF677 and GN15 rootstocks: insights into physiological, biochemical, and molecular mechanisms

Salinity is a common environmental stress that disrupts physiological and biochemical processes in plants, inhibiting growth. Silicon is a key element that enhances plant tolerance to such abiotic stresses. This study examined the effects of silicon supplementation on physiological, biochemical, and molecular responses of GF677 and GN15 rootstocks under NaCl-induced salinity stress. The experiment was conducted in a greenhouse using a factorial design with two rootstocks, three NaCl concentrations (0, 50, and 100 mM), and three silicon levels (0, 1, and 2 mM) in a randomized complete block design with three replicates. Salinity significantly reduced growth parameters, including shoot and root fresh and dry weights, RWC, and photosynthetic activity, with GN15 being more sensitive to salt stress than GF677. Silicon supplementation, especially at 2 mM, alleviated NaCl-induced damage, enhancing biomass retention and RWC under moderate and high NaCl levels. Additionally, silicon reduced electrolyte leakage, lipid peroxidation, and hydrogen peroxide accumulation, suggesting a protective role against oxidative stress. Biochemical analyses showed that silicon increased the accumulation of osmolytes such as proline, soluble sugars, glycine betaine, and total soluble protein, particularly in GF677. Silicon also boosted antioxidant enzyme activities, mitigating oxidative damage. In terms of mineral nutrition, silicon reduced Na+ and Cl- accumulation in leaves and roots, with the greatest reduction observed at 2 mM Si. Gene expression analysis indicated that NaCl stress upregulated key salt tolerance genes, including HKT1, AVP1, NHX1, and SOS1, with silicon application further enhancing their expression, particularly in GF677. The highest levels of gene expression were found in plants treated with both NaCl and 2 mM Si, suggesting that silicon improves salt tolerance by modulating gene expression. In conclusion, this study demonstrates the potential of silicon as an effective mitigator of NaCl stress in GF677 and GN15 rootstocks, particularly under moderate to high salinity conditions. Silicon supplementation enhances plant growth, osmotic regulation, reduces oxidative damage, and modulates gene expression for salt tolerance. Further research is needed to assess silicon's effectiveness under soil-based conditions and its applicability to other rootstocks and orchard environments. This study is the first to concurrently evaluate the physiological, biochemical, and molecular responses of GF677 and GN15 rootstocks to silicon application under salt stress conditions.

OsERF2 Acts as a Direct Downstream Target of OsEIL1 to Negatively Regulate Salt Tolerance in Rice

Salinity is a significant limiting factor that adversely affects plant growth, distribution and crop yield. Ethylene responsive factors play crucial roles in plant responses to and tolerance of various abiotic stresses. Recently, we revealed that OsERF2 is involved in root growth by transcriptionally regulating hormone and sugar signaling in rice. Here, we report that OsERF2 is a direct target gene of OsEIL1 and negatively regulates salt tolerance in rice. Compared to the wild type, the gain-of-function mutant of OsERF2 (nsf2857) and the knockdown of OsERF2 via an artificial microRNA (Ami-ERF2) exhibited decreased and increased salt tolerance, respectively. The enhanced salt tolerance observed in Ami-OsERF2 lines was associated with lower accumulations of malondialdehyde and reactive oxygen species (ROS) under salt stress, while the opposite was true for nsf2857 plants, which exhibited decreased salt tolerance. At the transcriptional level, several stress-related genes encoding ROS and NAD(P)H-related oxidoreductases were downregulated in nsf2857 plants but upregulated in Ami-ERF2 plants. Furthermore, yeast one-hybrid and ChIP assays revealed that OsEIL1 can bind to the of EBS cis element present in the promoter of OsERF2 (-bp), suggesting that OsEIL1 may directly regulate the expression of OsERF2. Collectively, our findings indicate that OsERF2 is a direct downstream factor involved in the regulation of salt tolerance in rice, highlighting its potential application in the genetic improvement of tolerance to abiotic stresses in this crop.

Comparative Analysis of Physiological Parameters, Antioxidant Defense, Ion Regulation, and Gene Expression in Two Distinct Maize Hybrids Under Salt Stress at Seedling Stage

Salinity significantly impacts maize production globally, requiring a deeper understanding of maize response mechanisms to salt stress. This study assessed the response of two Egyptian maize hybrids, SC-10 and TWC-321, under salt stress (200 mM NaCl) and non-stressed conditions to identify traits and mechanisms linked to enhanced salinity tolerance. Both hybrids accumulated similar Na+ levels in leaves, but TWC-321 exhibited better ion regulation, with lower Na+ concentrations and Na+ to K+ ratio in roots. While SC-10 showed a reduction in leaf K+ levels, TWC-321 maintained stable K+ levels, highlighting its superior salinity tolerance. TWC-321 also demonstrated better oxidative stress management, as evidenced by lower malondialdehyde levels and significantly higher total chlorophyll content, relative water content, and stomatal conductance. Proline accumulation was more pronounced in TWC-321, and it showed higher antioxidant enzyme activities (SOD, CAT, and POD) compared to SC-10, which exhibited lower SOD and POD activities. Gene expression analysis demonstrated distinct responses to salt stress between the hybrids. Although zmHKT1;5 was similarly induced in both hybrids, TWC-321 exhibited higher expression levels of zmHKT2 (1.96-fold compared to 1.42-fold in SC-10) and upregulated zmNHX1 (1.92-fold), whereas zmNHX1 expression was slightly reduced in SC-10 (0.8-fold). Additionally, TWC-321 achieved a greater total dry weight than SC-10 under salinity stress, highlighting its superior performance and resilience. These findings indicate that enhanced Na+ exclusion and sequestration mechanisms mediate the salinity tolerance of TWC-321. Correlation analysis under salinity stress identified key indicators of salinity tolerance, including increased activity of CAT and SOD, elevated proline accumulation, and higher K+ content. Consequently, the salinity tolerance of TWC-321 can be attributed to its effective ion regulation, stable photosynthetic pigment levels, improved osmotic adjustment, enhanced water retention, and potent antioxidant defense system. These insights are highly valuable for breeding programs focused on developing salt-tolerant maize hybrids.

Mitigation of salinity stress in salt-sensitive rice seedlings via phytohormone synthesis, antioxidant defence enhancement, and ion balance regulation induced by 5-aminolevulinic acid-producing purple non-sulfur bacteria

Salt stress, intensified by climate change, is a significant threat to rice production, a vital staple for over half the world's population. This makes addressing salt stress in rice cultivation a pressing issue. This study investigates the role of PNSB as a biostimulant in enhancing salinity tolerance of salt-sensitive rice seedlings, addressing existing gaps in knowledge on physiological and biochemical impacts under saline stress. We inoculated salt-sensitive rice seedlings with PNSB under 80 mmol NaCl stress in a controlled environment. After a 5-day treatment, we conducted biochemical and physiological analyses. Salinity stress induced oxidative stress in salt-sensitive rice seedlings. However, application of 5-ALA-producing PNSB mitigated stress, elevated 5-ALA in shoots by 23%, roots by 190.5%, and chlorophyll content by 105.0%. PNSB treatment also reduced superoxide radicals (O2 •-) and H2O2 by 26.7% and 38.7%, respectively, related to increased activity of the antioxidant enzymes, SOD (142.9%) and APX (41.8%). This led to lower electrolyte leakage (25.2%) and MDA (17.4%), indicating reduced ROS. Additionally, proline and soluble sugar content decreased by 29.2% and 72.5%, respectively. PNSB treatment also reduced sodium to potassium ion content in both shoots (31.2%) and roots (27.4%) of salt-stressed rice seedlings. These findings suggest that PNSB may facilitate nutrient solubilization and ion balance, thereby mitigating the adverse effects of salinity, with potential implications for sustainable agricultural practices to improve crop yield in saline environments. Future research should focus on elucidating the specific biochemical pathways involved in PNSB-mediated stress tolerance and exploring their application across diverse crop species and varying stress conditions.

Comprehensive review of plant small signaling peptides: From stress adaptation mechanisms to practical solutions for crop resilience

Small signaling peptides (SSPs), short proteins of fewer than 100 amino acids, serve as pivotal signaling molecules with diverse structural features, post-translational modifications, and functional roles. They regulate various aspects of plant growth and development by modulating specific cellular signaling pathways. Research has shown that many SSPs are essential for mediating responses to environmental stresses. This review presents the structure, characteristics, and classification of plant SSPs and elucidates their roles in resistance signaling pathways through interactions with their specific receptors. We then summarize recent findings on the biological functions and regulatory mechanisms of SSPs in response to both biotic and abiotic stresses. Finally, we discuss the potential applications and future prospects of these peptides in plant protection. This review offers valuable insights for enhancing plant resilience to environmental stress and advancing sustainable agricultural practices, while also providing key references and perspectives to accelerate research on SSPs in plants.

A comprehensive review on rice responses and tolerance to salt stress

The challenge of salinity stress significantly impacts global rice production, especially in coastal and arid regions where the salinization of agricultural soils is on the rise. This review explores the complex physiological, biochemical, and genetic mechanisms contributing to salinity tolerance in rice (Oryza sativa L.) while examining agronomic and multidisciplinary strategies to bolster resilience. Essential adaptations encompass the regulation of ionic balance, the management of antioxidants, and the adjustments to osmotic pressure, all driven by genes such as OsHKT1;5 and transcription factors like OsbZIP73. The evolution of breeding strategies, encompassing traditional methods and cutting-edge innovations, has produced remarkable salt-tolerant varieties such as FL478 and BRRI dhan47. The advancements in this field are enhanced by agronomic innovations, including integrated soil management, crop rotation, and chemical treatments like spermidine, which bolster stress tolerance through antioxidant activity and transcriptional regulation mechanisms. Case studies from South Asia, Sub-Saharan Africa, the Middle East and, Australia demonstrate the transformative potential of utilizing salt-tolerant rice varieties; however, challenges persist, such as the polygenic nature of salinity tolerance, environmental variability, and socioeconomic barriers. The review highlights the importance of collaborative efforts across various disciplines, merging genomic technologies, sophisticated phenotyping, and inclusive breeding practices to foster climate-resilient and sustainable rice cultivation. This work seeks to navigate the complexities of salinity stress and its implications for global food security, employing inventive and cohesive strategies to confront the challenges posed by climate change.

Exploring Alternative Splicing in Response to Salinity: A Tissue-Level Comparative Analysis Using Arabidopsis thaliana Public Transcriptomic Data

Increased soil salinity is a major threat to global agriculture and food security, caused mainly by anthropogenic activities and changing climatic cycles. Plants responses to salinity involve multiple regulatory layers, from transcriptome reprogramming to proteomic and metabolomic changes. Alternative splicing (AS) plays a role in coordinating the response to salinity, yet its extent, tissue, and condition specificity, remain poorly understood aspects. In this study, we used 52 publicly available RNA-seq datasets of salinity treatment to identify differential alternative splicing (DAS) events and genes participating in the response to this stimulus. Our findings reveal that either independently or coordinately, AS can regulate up to 20% of the transcriptome detected in Arabidopsis, with treatment intensity being the most determining factor. Moreover, we show that AS regulation was highly tissue-specific, with roots displaying strong AS-mediated stress responses. Furthermore, cross-stress comparisons showed that roots have a core set of AS-regulated genes associated with stress response and development, with functionally distinct sets of genes when comparing salt with other stresses, while also conserving a relevant condition-specific response. We demonstrate the need to integrate AS analysis to better understand plant adaptation mechanisms and highlight the key role of AS in salinity responses, revealing shared AS regulation between salt, heat, and drought responses.

Genome-Wide Identification and Expression Profiling of ABA-Stress-Ripening (ASR) Gene Family in Barley (Hordeum vulgare L.)

Abscisic acid (ABA)-stress-ripening, or ABA-, stress-, and ripening-induced (ASR) proteins play an important role in responses to environmental stimuli. A total of ten barley HvASRs were identified in this study, which were unevenly distributed on three chromosomes. ASRs from barley, wheat, Brachypodium distachyon, rice, maize, foxtail millet, and tomato were classified into two distinct clusters based on phylogenetic analysis. Notably, ASRs from Poaceae were evenly distributed between these two clusters. HvASRs contained a typical ABA/WDS domain, and exhibited similar motif arrangements. Two gene pairs of tandem duplicates (HvASR4/5/6/7 and HvASR8/9) were identified among HvASRs. Cis-acting elements involved in hormone and stress responses, including ABRE, MYB, ARE, and STRE, were consistently identified in the promoters of HvASRs. The expression of HvASRs was substantially influenced by salt, osmotic, and ABA treatments in the roots and leaves of barley seedlings. HvASR2 acts as a transcriptional repressor, whereas HvASR3 serves as a transcriptional activator. These results enhance our understanding of the HvASR family and provide a foundation for further functional characterization.

In Silico Characterization and Determination of Gene Expression Levels Under Saline Stress Conditions in the Zinc Finger Family of the C1-2i Subclass in Chenopodium quinoa Willd

Quinoa (Chenopodium quinoa) is recognized for its tolerance to abiotic stress, including salinity, and its recent genome sequencing has facilitated the study of the mechanisms underlying this adaptation. This study focused on characterizing the ZAT genes of the C2H2 subfamily in quinoa, evaluating their expression under saline stress. Eight ZAT genes were identified and analyzed in silico using genomic databases and bioinformatics tools, assessing their conserved domains, cis-regulatory motifs, and physicochemical characteristics. Additionally, germination assays, hydroponic cultivation, and gene expression analyses via qPCR were performed on halotolerant (UNSA_VP033) and halosensitive (UNSA_VP021) accessions exposed to different NaCl concentrations. The genes CqZAT4 and CqZAT6 showed high expression in the halotolerant accession under saline stress, correlating with increased dry matter, root length, and water retention. In contrast, the halosensitive accession exhibited lower tolerance, with significant reductions in these metrics. Promoter analysis revealed cis-elements associated with hormonal and stress responses. ZAT genes play a key role in quinoa's response to saline stress, with CqZAT4 and CqZAT6 standing out in the halotolerant accession. These findings could drive the development of more resilient varieties, contributing to agricultural sustainability in saline soils.

Multi-Omic Advances in Olive Tree (Olea europaea subsp. europaea L.) Under Salinity: Stepping Towards 'Smart Oliviculture'

Soil salinisation is threatening crop sustainability worldwide, mainly due to anthropogenic climate change. Molecular mechanisms developed to counteract salinity have been intensely studied in model plants. Nevertheless, the economically relevant olive tree (Olea europaea subsp. europaea L.), being highly exposed to soil salinisation, deserves a specific review to extract the recent genomic advances that support the known morphological and biochemical mechanisms that make it a relative salt-tolerant crop. A comprehensive list of 98 olive cultivars classified by salt tolerance is provided, together with the list of available olive tree genomes and genes known to be involved in salt response. Na+ and Cl- exclusion in leaves and retention in roots seem to be the most prominent adaptations, but cell wall thickening and antioxidant changes are also required for a tolerant response. Several post-translational modifications of proteins are emerging as key factors, together with microbiota amendments, making treatments with biostimulants and chemical compounds a promising approach to enable cultivation in already salinised soils. Low and high-throughput transcriptomics and metagenomics results obtained from salt-sensitive and -tolerant cultivars, and the future advantages of engineering specific metacaspases involved in programmed cell death and autophagy pathways to rapidly raise salt-tolerant cultivars or rootstocks are also discussed. The overview of bioinformatic tools focused on olive tree, combined with machine learning approaches for studying plant stress from a multi-omics perspective, indicates that the development of salt-tolerant cultivars or rootstocks adapted to soil salinisation is progressing. This could pave the way for 'smart oliviculture', promoting more productive and sustainable practices under salt stress.

A Comprehensive Evaluation of Soybean Germplasm Resources for Salt Tolerance During Germination

Salt stress impedes normal development, compromises plant quality, and reduces crop yield. The germination phase in soybean marks the initial stage of its growth cycle. Characterizing salt tolerance during this period can help stimulate soybean growth in natural environments and aid the rapid screening of salt-tolerant soybean varieties. Our study characterized the salt tolerance of 36 soybean germplasms in culture dishes during the germination period. Soybeans were subjected to varying concentrations (0, 60, 120, and 180 mmol/L) of NaCl solution to simulate diverse levels of salt stress, and parameters such as germination energy, germination rate, and root length were measured. Statistical techniques such as analysis of variance, membership function, cluster analysis, and quadratic regression equations were used, and the salt tolerance of these 36 soybean germplasms was determined. The critical indicators and the most effective screening concentration for assessing the germination salt tolerance of soybean were identified. Soybeans tolerated low salt concentrations; however, salt concentrations greater than 120 mmol/L significantly inhibited germination indicators. The germination rate, germination vigor, vitality index, seed germination index, total fresh weight, and total dry weight could be used to identify salt tolerance. The semi-lethal concentration of soybean was 155.4 mmol/L, and the coefficient of variation was 20.00%, indicating that it could be used as a screening concentration for evaluating salt tolerance during soybean germination. A total of 36 soybean varieties were classified into four salt tolerance levels through cluster analysis. QN-27, QN-35, and QN-36 were highly salt-resistant materials, and QN-2, QN-17, and QN-19 were salt-sensitive materials. Characterizing salt tolerance during soybean germination can facilitate the selection and breeding of salt-tolerant soybean varieties. Future research utilizing this approach can aid in the selection of soybean varieties with salinity tolerance.

Genome-wide identification and analysis of autophagy-related (ATG) genes in Lycium ruthenicum Murray reveals their crucial roles in salt stress tolerance

Autophagy is a highly conserved intracellular degradation system that is crucial for nutrient recycling, thus regulating plant growth and development as well as in response to various stresses. Halophytic plant Lycium ruthenicum Murray (L. ruthenicum) is considered as a potential model plant for studying the physiological mechanisms of salt stress tolerance in plants. Although the genome sequence of L. ruthenicum is available, the characteristics and functions of the salt stress-related genes remain largely unknown. In the present study, a total of 36 AuTophaGy-related (ATG) genes were identified in L. ruthenicum and detailed characteristics of them were given. Quantitative real-time polymerase chain reaction analysis revealed that the expression of 25 LrATGs was significantly upregulated after salt stress treatments. Furthermore, the autophagic marker line pSuper:GFP-LrATG8g was generated and used to demonstrate the salt stress-induced autophagy, as revealed by measuring autophagic flux and observing autophagosome formation. The pSuper:LrATG5-GFP overexpression (OE) lines were also generated and further phenotypic analysis showed that OE-LrATG8g and OE-LrATG5 plants exhibited better salt tolerance than that of WT plants. To the best of our knowledge, this study firstly reports a detailed overview of LrATGs-mediated autophagy in L. ruthenicum response to salt stress. These findings contribute to a global understanding of the characteristics of ATG genes in L. ruthenicum and lay a foundation for future functional study.

Isolation of OSCAs in wheat and over-expression of TaOSCA14D increased salt stress tolerance

Salt stress is a major environmental factor that limits plant growth and productivity. In the early stage of salt stress, the intracellular Ca2+ concentration elevates, thereby triggering osmotic stress tolerance signaling pathway. OSCAs encode hyperosmotic gated calcium channels and function as osmotic sensors in Arabidopsis. But the functions of OSCAs in wheat responding to salt stress have not been elucidated. In this study, we identified 42 TaOSCAs and examined their expression pattern in 12 tissues and under salt stress. Further, the salt inducible TaOSCA14D was selected for functional study in response to salt stress. TaOSCA14D was induced by NaCl, PEG, exogenous ABA treatment. Over-expression of TaOSCA14D in Arabidopsis and wheat increased salt stress tolerance. Salt stress related marker genes SnRK2s, ABFs, RD29B were higher expressed in TaOSCA14D transgenic plants than in the wild type under NaCl treatment. Furthermore, the soluble sugar and proline content were higher in transgenic plants than in wild-type ones. Over-expression of TaOSCA14D promoted flowering, decreased spike length and the grain number of per spike. All these results shed some light on the function of OSCAs in tolerance to salt stress and its roles in agronomic trait in wheat.

Deciphering crucial salt-responsive genes in Brassica napus via statistical modeling and network analysis on dynamic transcriptomic data

Soil salinization severely impacts crop yields, threatening global food security. Understanding the salt stress response of Brassica napus (B. napus), a vital oilseed crop, is crucial for developing salt-tolerant varieties. This study aims to comprehensively characterize the dynamic transcriptomic response of B. napus seedlings to salt stress, identifying key genes and pathways involved in this process. RNA-sequencing on 43 B. napus seedling samples are performed, including 24 controls and 19 salt-stressed plants, at time points of 0, 1, 3, 6, and 12 h. Differential expression analysis using 33 control experiments (CEs) identified 39,330 differentially expressed genes (DEGs). Principal component analysis (PCA) and a novel penalized logistic regression with k-Shape clustering (PLRKSC) method identify 346 crucial DEGs. GO enrichment, differential co-expression network analysis, and functional validation through B. napus transformation verify the functional roles of the identified DEGs. The analysis reveals highly dynamic and tissue-specific expression patterns of DEGs under salt stress. The identified 346 crucial DEGs include those involved in leaf and root development, stress-responsive transcription factors, and genes associated with the salt overly sensitive (SOS) pathway. Specifically, Overexpression of RD26 (BnaC07g40860D) in B. napus significantly enhances salt tolerance, confirming its role in salt stress response. This study provides a comprehensive understanding of the B. napus salt stress response at the transcriptomic level and identifies key candidate genes, such as RD26, for developing salt-tolerant varieties. The methodologies established can be applied to other omics studies of plant stress responses.

Physiological and molecular mechanisms of exogenous salicylic acid in enhancing salt tolerance in tobacco seedlings by regulating antioxidant defence system and gene expression

Introduction

Salt stress has emerged as a predominant abiotic factor that jeopardizes global crop growth and yield. The plant hormone salicylic acid (SA) has notable potential in mitigating salt toxicity, yet its mechanism in enhancing the salinity tolerance of tobacco plants is not well explored.

Methods

This study aimed to assess the potential benefits of exogenous SA application (1.0 mM) on tobacco seedlings subjected to saline soil conditions.

Results

The foliar spray of SA partially mitigated these salt-induced effects, as evidenced by a reduction of malondialdehyde content, and improvements of leaf K+/Na+ ratios, pigment biosynthesis, and electron transport efficiency under NaCl stress. Additionally, SA increased the contents of total phenolic compound and soluble protein by 16.2% and 28.7% to alleviate NaCl-induced oxidative damage. Under salt stressed conditions, the activities of antioxidant enzymes, including superoxide dismutase, ascorbate peroxidase, catalase, and peroxidase increased by 4.2%~14.4% in SA sprayed tobacco seedlings. Exogenous SA also increased ascorbate and glutathione levels and reduced their reduced forms by increasing the activities of glutathione reductase, ascorbate peroxidase, monodehydroascorbate reductase and dehydroascorbate reductase. qRT-PCR analysis revealed that the key genes regulating SA biosynthesis, carbon assimilation, the antioxidant system and the ascorbate-glutathione cycle were activated by SA under conditions of salt stress.

Discussion

Our study elucidates the physiological and molecular mechanisms of exogenous SA in enhancing plant salt tolerance and provides a practical basis for crop improvement in saline environments.

Time-Course Transcriptomics Analysis Reveals Molecular Mechanisms of Salt-Tolerant and Salt-Sensitive Cotton Cultivars in Response to Salt Stress

Salt stress is an environmental factor that limits plant seed germination, growth, and survival. We performed a comparative RNA sequencing transcriptome analysis during germination of the seeds from two cultivars with contrasting salt tolerance responses. A transcriptomic comparison between salt-tolerant cotton cv Jin-mian 25 and salt-sensitive cotton cv Su-mian 3 revealed both similar and differential expression patterns between the two genotypes during salt stress. The expression of genes related to aquaporins, kinases, reactive oxygen species (ROS) scavenging, trehalose biosynthesis, and phytohormone biosynthesis and signaling that include ethylene (ET), gibberellin (GA), abscisic acid (ABA), jasmonic acid (JA), and brassinosteroid (BR) were systematically investigated between the cultivars. Despite the involvement of these genes in cotton's response to salt stress in positive or negative ways, their expression levels were mostly similar in both genotypes. Interestingly, a PXC2 gene (Ghir_D08G025150) was identified, which encodes a leucine-rich repeat receptor-like protein kinase (LRR-RLK). This gene showed an induced expression pattern after salt stress treatment in salt-tolerant cv Jin-mian 25 but not salt-sensitive cv Su-mian 3. Our multifaceted transcriptome approach illustrated a differential response to salt stress between salt-tolerant and salt-sensitive cotton.

Revisiting the role of light signaling in plant responses to salt stress

As one of the grave environmental hazards, soil salinization seriously limits crop productivity, growth, and development. When plants are exposed to salt stress, they suffer a sequence of damage mainly caused by osmotic stress, ion toxicity, and subsequently oxidative stress. As sessile organisms, plants have developed many physiological and biochemical strategies to mitigate the impact of salt stress. These strategies include altering root development direction, shortening the life cycle, accelerating dormancy, closing stomata to reduce transpiration, and decreasing biomass. Apart from being a prime energy source, light is an environmental signal that profoundly influences plant growth and development and also participates in plants' response to salt stress. This review summarizes the regulatory network of salt tolerance by light signals in plants, which is vital to further understanding plants' adaptation to high salinity. In addition, the review highlights potential future uses of genetic engineering and light supplement technology by light-emitting diode (LED) to improve crop growth in saline-alkali environments in order to make full use of the vast saline land.

Quantitative N-glycoproteomics characterization of differential N-glycosylation in Sorghum bicolor under salinity stress

Salt stress is one of the significant environmental stresses that severely affect plant growth and development. Here, we report quantitative N-glycoproteomics characterization of differential N-glycosylation in Sorghum bicolor under low, median and high salinity stress. 21,621 intact N-glycopeptides coming from the combination of 127 N-glycan structures on 6574 N-glycosites from 5321 proteins were identified; differential N-glycosylation was observed for 682 N-glycoproteins which are mainly involved in the pathways of biosynthesis of secondary metabolites, biosynthesis of amino acids and several metabolic pathways. 41 N-glycan structures modifying on 338 N-glycopeptides from 122 glycoproteins were co-quantified and deregulated under at least one salt stress, including enzymes of energy production and carbohydrate metabolisms, cell wall organization related proteins, glycosyltransferases and so on. Intriguingly, with increasing salt concentration, there was an increase in the percentage of complex N-glycans on the altered N-glycopeptides. Furthermore, the observation of glycoproteins with distinct salt sensitivity is noteworthy, particularly the upregulated hyposensitive glycoproteins that predominantly undergo complex N-glycan modification. This is the first N-glycoproteome description of salt stress response at the intact N-glycopeptide level in sorghum and a further validation of data reported here would likely provide deeper insights into the stress physiology of this important crop plant.

A glutathione S-transferase regulates lignin biosynthesis and enhances salt tolerance in tomato

Salt stress adversely affects the growth and yield of crops. Glutathione S-transferases (GSTs) are involved in plant growth and responses to biotic and abiotic stresses. In this study, 400 mm NaCl stress significantly induced the expression of Glutathione S-transferase U43 (SlGSTU43) in the roots of the wild-type tomato (Solanum lycopersicum L.) plants. Overexpressing SlGSTU43 enhanced the ability of scavenging reactive oxygen species in tomato leaves and roots under NaCl stress, while SlGSTU43 knock-out mutants showed the opposite performance. RNA sequencing analysis revealed that overexpressing SlGSTU43 affected the expression of genes related to lignin biosynthesis. We demonstrated that SlGSTU43 can regulate the lignin content in tomato through its interaction with SlCOMT2, a key enzyme involved in lignin biosynthesis, and promote the growth of tomato plants under NaCl stress. In addition, SlMYB71 and SlWRKY8 interact each other, and can directly bind to the promoter of SlGSTU43 to transcriptionally activate its expression separately or in combination. When SlMYB71 and SlWRKY8 were silenced in tomato plants individually or collectively, the plants were sensitive to NaCl stress, and their GST activities and lignin contents decreased. Our research indicates that SlGSTU43 can enhance salt stress tolerance in tomato by regulating lignin biosynthesis, which is regulated by interacting with SlCOMT2, as well as SlMYB71 and SlWRKY8. This finding broadens our understanding of GST functions.

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.

SPIRRIG is required for BRICK1 stability and salt stress induced root hair developmental plasticity in Arabidopsis

Developmental plasticity is critical for plants to adapt to constantly changing environments. Plant root hairs display dramatic plasticity under different environments and therefore play crucial roles in defense against environmental stressors. Here, we report the isolation of an Arabidopsis mutant, salinity over-sensitive mutant 1-1 (som1-1), also exhibiting root hair developmental defects. Map-based cloning and allelic analyses confirmed that som1-1 is a new mutant allele of SPIRRIG (SPI), which encodes a Beige and Chediak Higashi (BEACH) domain-containing protein. SPI has been reported to facilitate actin dependent root hair development by temporally and spatially regulating the expression of BRICK1 (BRK1), a subunit of the SCAR/WAVE actin nucleating promoting complex. Our living cell imaging examinations revealed that salt stress induces an altered actin organization in root hair that mimics those in the spi mutant, implying SPI may respond to salt stress induced root hair plasticity by modulating actin cytoskeleton organization. Furthermore, we found BRK1 is also involved in root hair developmental change under salt stress, and overexpression of BRK1 resulted in root hairs over-sensitive to salt stress as those in spi mutant. Moreover, based on biochemical analyses, we found BRK1 is unstable and SPI mediates BRK1 stability. Functional loss of SPI results in the accumulation of steady-state of BRK1.

Enhancing Crop Resilience: The Role of Plant Genetics, Transcription Factors, and Next-Generation Sequencing in Addressing Salt Stress

Salt stress is a major abiotic stressor that limits plant growth, development, and agricultural productivity, especially in regions with high soil salinity. With the increasing salinization of soils due to climate change, developing salt-tolerant crops has become essential for ensuring food security. This review consolidates recent advances in plant genetics, transcription factors (TFs), and next-generation sequencing (NGS) technologies that are pivotal for enhancing salt stress tolerance in crops. It highlights critical genes involved in ion homeostasis, osmotic adjustment, and stress signaling pathways, which contribute to plant resilience under saline conditions. Additionally, specific TF families, such as DREB, NAC (NAM, ATAF, and CUC), and WRKY, are explored for their roles in activating salt-responsive gene networks. By leveraging NGS technologies-including genome-wide association studies (GWASs) and RNA sequencing (RNA-seq)-this review provides insights into the complex genetic basis of salt tolerance, identifying novel genes and regulatory networks that underpin adaptive responses. Emphasizing the integration of genetic tools, TF research, and NGS, this review presents a comprehensive framework for accelerating the development of salt-tolerant crops, contributing to sustainable agriculture in saline-prone areas.

Regulation of hydrogen rich water on strawberry seedlings and root endophytic bacteria under salt stress

Salt stress could lead to plant growth barriers and crop yield reduction. Strawberries are sensitive to salt stress, and improving salt tolerance is important for strawberry production. This study aimed to explore the potential of hydrogen-rich water (HRW) to enhance salt tolerance in strawberries. Through pot experiments, we investigated how HRW affects plant growth, ion absorption, osmotic stress, oxidative stress, antioxidant enzyme levels, hormone levels, and root endophytic bacteria in strawberry seedlings under salt stress. The results showed that under 100 mM NaCl treatment, 50% and 100% HRW treatments significantly increased strawberry biomass by 0.29 g and 0.54g, respectively, wherein, 100% HRW significantly increased the shoot and root length by 15.34% and 24.49%, respectively. In addition, under salt stress the absorption of K+ by strawberry seedlings was increased with the HRW supplement, while the absorption of Na+ was reduced. Meanwhile, HRW treatment reduced the transfer of Na+ from root to shoot. Furthermore, under salt stress, HRW treatment increased the relative water content (RWC) by 12.35%, decreased the electrolyte leakage rate (EL) by 7.56%. HRW modulated phytohormone levels in strawberry seedlings, thereby alleviating the salt stress on strawberries. Moreover, HRW was found to promote plant growth by altering the diversity of bacteria in strawberry roots and recruiting specific microorganisms, such as Tistella. Our findings indicate that HRW could help restore the microecological homeostasis of strawberry seedlings, thus further mitigating salt stress. This study provides a novel perspective on the mechanisms by which HRW alleviates salt stress, thereby enriching the scientific understanding of hydrogen's applications in agriculture.

Seed Priming with Dynamically Transformed Selenium Nanoparticles to Enhance Salt Tolerance in Rice

Seed priming with nanomaterials is an emerging approach for improving plant stress tolerance. Here, we demonstrated a mechanism for enhancing salt tolerance in rice under salt stress via priming with nonstimulatory nanoparticles such as selenium nanoparticles (SeNPs), distinct from stimulatory nanomaterials. Due to the dynamic transformation ability of SeNPs, SeNP priming could enhance rice salt tolerance by mediating the glutathione cycle to eliminate excess reactive oxygen species (ROS). During priming, SeNPs penetrated rice seeds and transitioned into a soluble form (99.9%) within the embryo endosperm. Subsequently, the soluble selenium (Se) was transported to rice roots and metabolized into various Se-related derivatives, including selenomethionine (SeMet), Na2SeO3 (Se IV), selenocysteine (SeCys2), and methylselenocysteine (MeSeCys). These derivatives significantly enhanced the root activities of key enzymes such as glutathione peroxidase (GSH-PX), glutathione reductase (GR), catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) by 24.97%, 47.98%, 16.23%, 16.81%, and 14.82%, respectively, thus reinforcing the glutathione cycle and ROS scavenging pathways. Moreover, these alterations induced transcriptional changes in rice seedlings, with genes involved in signal transduction, transcription factors (TFs), ROS scavenging, and protein folding being upregulated, activating signal perception and self-repair mechanisms. These findings offer valuable insights for the agricultural application of nanomaterials.

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.

Preinoculation with Bradyrhizobium japonicum enhances the salt tolerance of Glycine max seedlings by regulating polyamine metabolism in roots

Rhizobia are common symbiotic microorganisms in the root system of leguminous plants that can usually provide nitrogen to the host through nitrogen fixation. Studies have shown that rhizobium-preinoculated soybean plants usually exhibit improved salt tolerance, but the underlying mechanism is not fully understood. In this paper, transcriptome sequencing (RNA-seq) revealed that preinoculation with rhizobia affected polyamine (PA) metabolism in soybean roots. The assay of PA contents showed that preinoculation with rhizobia significantly increased the putrescine (Put) content in roots and leaves during short-term salt treatment (0-5 d). Long-term salt treatment (5-7 d) resulted in a high Put content and significantly increased Spm and Spd contents, resulting in a rapid increase in the Put/(Spd + Spm) ratio (0-5 d) and subsequent decrease. Moreover, rhizobium preinoculation of soybean plants resulted in increased contents of conjugated and bound PAs under salt stress. Further transcriptome sequencing, PA contents, PA synthase expression and activity analysis revealed that GmADC may be a key gene related to salt tolerance in rhizobium-preinoculated soybean plants, and the GmADC-overexpressing soybean hairy-root composite plants exhibited less ROS damage, lower Cl-/NO3- ratios and Na+/K+ ratios, and stabilized ion homeostasis. Taken together, preinoculation with rhizobia increased the expression level and enzyme activity of arginine decarboxylase (ADC) in soybean roots, increased the content of Put in roots and leaves, and increased the content of conjugated and bound PAs in soybean plants, thereby alleviating the oxidative and ionic injuries of soybean plants and enhancing the salt tolerance.

Brassinosteroids Alleviate Salt Stress by Enhancing Sugar and Glycine Betaine in Pepper (Capsicum annuum L.)

Salt stress is a major abiotic factor that negatively impacts the growth, performance, and secondary metabolite production in pepper (Capsicum annuum L.) plants. Brassinosteroids (BRs) play a crucial role in enhancing plant tolerance to abiotic stress, yet their potential in mitigating salt stress in pepper plants, particularly by promoting sugar and glycine betaine accumulation, remains underexplored. In this study, we investigated the effects of the foliar application of 2,4-epibrassinolide (EBR) on salt-stressed pepper seedlings. Our findings revealed that EBR treatment significantly increased the levels of proline, sugar, and glycine betaine under salt stress compared to untreated controls. Moreover, EBR enhanced the antioxidant defense mechanisms in pepper seedlings by increasing sugar and glycine betaine levels, which contributed to the reduction of reactive oxygen species (ROS) and malondialdehyde (MDA) accumulation.

NaCl Stress Stimulates Phenolics Biosynthesis and Antioxidant System Enhancement of Quinoa Germinated after Magnetic Field Pretreatment

Our previous study showed that magnetic field pretreatment promoted germination and phenolic enrichment in quinoa. In this study, we further investigated the effects of NaCl stress on the growth and phenolic synthesis of germinated quinoa after magnetic field pretreatment (MGQ). The results showed that NaCl stress inhibited the growth of MGQ, reduced the moisture content and weight of a single plant, but increased the fresh/dry weight. The higher the NaCl concentration, the more obvious the inhibition effect. In addition, NaCl stress inhibited the hydrolysis of MGQ starch, protein, and fat but increased the ash content. Moreover, lower concentrations (50 and 100 mM) of NaCl stress increased the content of MGQ flavonoids and other phenolic compounds. This was due to the fact that NaCl stress further increased the enzyme activities of PAL, C4H, 4CL, CHS, CHI, and CHR and up-regulated the gene expression of the above enzymes. NaCl stress at 50 and 100 mM increased the DPPH and ABTS scavenging capacity of MGQ and increased the activities of antioxidant enzymes, including SOD, POD, CAT, APX, and GSH-Px, further enhancing the antioxidant system. Furthermore, principal component analysis showed that NaCl stress at 100 mM had the greatest combined effect on MGQ. Taken together, NaCl stress inhibited the growth of MGQ, but appropriate concentrations of NaCl stress, especially 100 mM, helped to further increase the phenolic content of MGQ and enhance its antioxidant system.

Understanding of Plant Salt Tolerance Mechanisms and Application to Molecular Breeding

Soil salinization is a widespread hindrance that endangers agricultural production and ecological security. High salt concentrations in saline soils are primarily caused by osmotic stress, ionic toxicity and oxidative stress, which have a negative impact on plant growth and development. In order to withstand salt stress, plants have developed a series of complicated physiological and molecular mechanisms, encompassing adaptive changes in the structure and function of various plant organs, as well as the intricate signal transduction networks enabling plants to survive in high-salinity environments. This review summarizes the recent advances in salt perception under different tissues, physiological responses and signaling regulations of plant tolerance to salt stress. We also examine the current knowledge of strategies for breeding salt-tolerant plants, including the applications of omics technologies and transgenic approaches, aiming to provide the basis for the cultivation of salt-tolerant crops through molecular breeding. Finally, future research on the application of wild germplasm resources and muti-omics technologies to discover new tolerant genes as well as investigation of crosstalk among plant hormone signaling pathways to uncover plant salt tolerance mechanisms are also discussed in this review.

Integrated transcriptomics, metabolomics and physiological analyses reveal differential response mechanisms of wheat to cadmium and/or salinity stress

Many soils face dual challenges of cadmium (Cd) contamination and salinization. However, the response of crops, especially wheat, to combined Cd and salinity stress is not understood. Here, wheat was grown in a hydroponic model for 14 days under single and combined Cd and NaCl stresses. Growth parameters, tissue Cd2+ and Na+ contents, and leaf chlorophyll (Chl), O2•-, and MDA levels were determined. Comparative transcriptomic and metabolomic analyses of the leaves were performed. The results showed that combined stress had a greater inhibitory effect on Chl contents and generated more O2•- and MDA, resulting in more severe wheat growth retardation than those under Cd or NaCl stress. Stress-induced decrease in Chl levels may be attributed to the inhibition of Chl biosynthesis, activation of Chl degradation, or a decline in glutamate content. Cd addition weakened the promotional effect of NaCl on SOS1 gene expression, thereby increasing the Na+ content. Contrastingly, NaCl supplementation downregulated the Nramp and ZIP gene expressions related to Cd uptake and transport, thereby impeding Cd2+ accumulation. All stresses enhanced tryptophan content via promoting tryptophan biosynthesis. Meanwhile, Cd and NaCl stresses activated phenylpropanoid biosynthesis and purine metabolism, respectively, thereby increasing the levels of caffeic acid, fumaric acid, and uric acid. Activating the TCA cycle was important in the wheat's response to combined stress. Additionally, NaCl and combined stresses affected starch and sucrose metabolism, resulting in sucrose and trehalose accumulation. Our findings provide a comprehensive understanding of the response of wheat to the combined Cd and salinity stress.

Pomegranate-Quinoa-Based Agroforestry System: An Innovative Strategy to Alleviate Salinity Effects and Enhance Land Use Efficiency in Salt-Affected Semiarid Regions

Salinity is a major problem, impeding soil productivity, agricultural sustainability, and food security, particularly in dry regions. This study integrates quinoa, a facultative halophyte, into a pomegranate-based agroforestry with saline irrigation in northeast Morocco. We aim to explore this agroforestry model's potential in mitigating salinity's effects on quinoa's agronomic and biochemical traits and evaluate the land equivalent ratio (LER). Field experiments in 2020 and 2021 used a randomized block design with three replicates, including monocropping and agroforestry systems, two salinity levels (1.12 and 10.5 dS m-1), four quinoa genotypes (Titicaca, Puno, ICBA-Q4, ICBA-Q5), and a pomegranate control. Salinity significantly decreased total dry matter (40.5%), root dry matter (50.7%), leaf dry matter (39.2%), and root-to-shoot ratio (7.7%). The impact was more severe in monoculture than in agroforestry, reducing dry matter (47.6% vs. 30.7%), grain yield (46.3% vs. 26.1%), water productivity (47.5% vs. 23.9%), and total sugar (19.2% vs. 5.6%). LER averaged 1.86 to 2.21, indicating 86-121% higher productivity in agroforestry. LER averaged 1.85 at 1.12 dS m-1 and 2.18 at 10.5 dS m-1, reaching 2.21 with pomegranate-ICBA-Q5 combination. Quinoa-pomegranate agroforestry emerges as an innovative strategy, leveraging quinoa's salt resistance and agroforestry's potential to mitigate salinity impacts while enhancing land use efficiency.

SOS2-AFP2 module regulates seed germination by inducing ABI5 degradation in response to salt stress in Arabidopsis

Soil salinity pose a significant challenge to global agriculture, threatening crop yields and food security. Understanding the salt tolerance mechanisms of plants is crucial for improving their survival under salt stress. AFP2, a negative regulator of ABA signaling, has been shown to play a crucial role in salt stress tolerance during seed germination. Mutations in AFP2 gene lead to increased sensitivity to salt stress. However, the underline mechanisms by which AFP2 regulates seed germination under salt stress remain elusive. In this study, we identified a protein interaction between AFP2 and SOS2, a Ser/Thr protein kinase known to play a critical role in salt stress response. Using a combination of genetic, biochemical, and physiological approaches, we investigated the role of the SOS2-AFP2 module in regulating seed germination under salt stress. Our findings reveal that SOS2 physically interacts with AFP2 and stabilizes it, leading to the degradation of the ABI5 protein, a negative transcription factor in seed germination under salt stress. This study sheds light on previously unknown connections within salt stress and ABA signaling, paving the way for novel strategies to enhance plant resilience against environmental challenges.

The Spartina alterniflora genome sequence provides insights into the salt-tolerance mechanisms of exo-recretohalophytes

Spartina alterniflora is an exo-recretohalophyte Poaceae species that is able to grow well in seashore, but the genomic basis underlying its adaptation to salt tolerance remains unknown. Here, we report a high-quality, chromosome-level genome assembly of S. alterniflora constructed through PacBio HiFi sequencing, combined with high-throughput chromosome conformation capture (Hi-C) technology and Illumina-based transcriptomic analyses. The final 1.58 Gb genome assembly has a contig N50 size of 46.74 Mb. Phylogenetic analysis suggests that S. alterniflora diverged from Zoysia japonica approximately 21.72 million years ago (MYA). Moreover, whole-genome duplication (WGD) events in S. alterniflora appear to have expanded gene families and transcription factors relevant to salt tolerance and adaptation to saline environments. Comparative genomics analyses identified numerous species-specific genes, significantly expanded genes and positively selected genes that are enriched for 'ion transport' and 'response to salt stress'. RNA-seq analysis identified several ion transporter genes including the high-affinity K+ transporters (HKTs), SaHKT1;2, SaHKT1;3 and SaHKT1;8, and high copy number of Salt Overly Sensitive (SOS) up-regulated under high salt conditions, and the overexpression of SaHKT2;4 in Arabidopsis thaliana conferred salt tolerance to the plant, suggesting specialized roles for S. alterniflora to adapt to saline environments. Integrated metabolomics and transcriptomics analyses revealed that salt stress activate glutathione metabolism, with differential expressions of several genes such as γ-ECS, GSH-S, GPX, GST and PCS in the glutathione metabolism. This study suggests several adaptive mechanisms that could contribute our understanding of evolutional basis of the halophyte.

Regulatory Dynamics of Plant Hormones and Transcription Factors under Salt Stress

The negative impacts of soil salinization on ion homeostasis provide a significant global barrier to agricultural production and development. Plant physiology and biochemistry are severely affected by primary and secondary NaCl stress impacts, which damage cellular integrity, impair water uptake, and trigger physiological drought. Determining how transcriptional factors (TFs) and hormone networks are regulated in plants in response to salt stress is necessary for developing crops that tolerate salt. This study investigates the complex mechanisms of several significant TF families that influence plant responses to salt stress, involving AP2/ERF, bZIP, NAC, MYB, and WRKY. It demonstrates how these transcription factors (TFs) help plants respond to the detrimental effects of salinity by modulating gene expression through mechanisms including hormone signaling, osmotic stress pathway activation, and ion homeostasis. Additionally, it explores the hormonal imbalances triggered by salt stress, which entail complex interactions among phytohormones like jasmonic acid (JA), salicylic acid (SA), and abscisic acid (ABA) within the hormonal regulatory networks. This review highlights the regulatory role of key transcription factors in salt-stress response, and their interaction with plant hormones is crucial for developing genome-edited crops that can enhance agricultural sustainability and address global food security challenges.

Physiological Responses and Salt Tolerance Evaluation of Different Varieties of Bougainvillea under Salt Stress

Soil salinization significantly impacts the ecological environment and agricultural production, posing a threat to plant growth. Currently, there are over 400 varieties of Bougainvillea with horticultural value internationally. However, research on the differences in salt tolerance among Bougainvillea varieties is still insufficient. Therefore, this study aims to investigate the physiological responses and tolerance differences of various Bougainvillea varieties under different concentrations of salt stress, reveal the effects of salt stress on their growth and physiology, and study the adaptation mechanisms of these varieties related to salt stress. The experimental materials consisted of five varieties of Bougainvillea. Based on the actual salinity concentrations in natural saline-alkali soils, we used a pot-controlled salt method for the experiment, with four treatment concentrations set: 0.0% (w/v) (CK), 0.2% (w/v), 0.4% (w/v), and 0.6% (w/v). After the Bougainvillea plants grew stably, salt stress was applied and the growth, physiology, and salt tolerance of the one-year-old plants were systematically measured and assessed. The key findings were as follows: Salt stress inhibited the growth and biomass of the five varieties of Bougainvillea; the 'Dayezi' variety showed severe salt damage, while the 'Shuihong' variety exhibited minimal response. As the salt concentration and duration of salt stress increase, the trends of the changes in antioxidant enzyme activity and osmotic regulation systems in the leaves of the five Bougainvillea species differ. Membrane permeability and the production of membrane oxidative products showed an upward trend with stress severity. The salt tolerance of the five varieties of Bougainvillea was comprehensively evaluated through principal component analysis. It was found that the 'Shuihong' variety exhibited the highest salt tolerance, followed by the 'Lvyehuanghua', 'Xiaoyezi', 'Tazi', and 'Dayezi' varieties. Therefore, Bougainvillea 'Shuihong', 'Lvyehuanghua', and 'Xiaoyezi' are recommended for extensive cultivation in saline-alkali areas. The investigation focuses primarily on how Bougainvillea varieties respond to salt stress from the perspectives of growth and physiological levels. Future research could explore the molecular mechanisms behind the responses to and tolerance of different Bougainvillea varieties as to salt stress, providing a more comprehensive understanding and basis for practical applications.

Integrated metabolomics and transcriptomics reveal that HhERF9 positively regulates salt tolerance in Hibiscus hamabo Siebold & Zuccarini

Hibiscus hamabo Siebold & Zuccarini is one of the few semi-mangrove plants in the genus Hibiscus that can survive in saline-alkali soil and flooded land, but the mechanism underlying its adaptation to salt soil remains unknown. Here, to uncover this unsolved mystery, we characterized the changes in the accumulation of specific metabolites under salt stress in H. hamabo by integrating physiological, metabolic, and transcriptomic data, and found that osmotic adjustment and abscisic acid (ABA) is highly associated with the salt stress response. Further, a weighted gene co-expression network analysis was performed on the root transcriptome data, which identified three key candidate transcription factors responsive to salt stress. Among them, the expression HhERF9 was significantly upregulated under salt stress and ABA treatment and was involved in regulating the expression of genes related to the salt stress response. Further research indicated that HhERF9 enhances the accumulation of proline and soluble sugars by regulating the expression of genes such as NHX2 and P5CS. These findings provide a reference for improving H. hamabo through targeted genetic engineering and lay a theoretical foundation for its future promotion and cultivation in saline-alkali areas.

Small Peptides: Orchestrators of Plant Growth and Developmental Processes

Small peptides (SPs), ranging from 5 to 100 amino acids, play integral roles in plants due to their diverse functions. Despite their low abundance and small molecular weight, SPs intricately regulate critical aspects of plant life, including cell division, growth, differentiation, flowering, fruiting, maturation, and stress responses. As vital mediators of intercellular signaling, SPs have garnered significant attention in plant biology research. This comprehensive review delves into SPs' structure, classification, and identification, providing a detailed understanding of their significance. Additionally, we summarize recent findings on the biological functions and signaling pathways of prominent SPs that regulate plant growth and development. This review also offers a perspective on future research directions in peptide signaling pathways.

Gossypium arboreum PPD2 facilitates root architecture development to increase plant resilience to salt stress

The jasmonic acid (JA) signaling pathway plays an important role in plant responses to abiotic stresses. The PEAPOD (PPD) and jasmonate ZIM-domain (JAZ) protein in the JA signaling pathway belong to the same family, but their functions in regulating plant defense against salt stress remain to be elucidated. Here, Gossypium arboreum PPD2 was overexpressed in Arabidopsis thaliana and systematically silenced in cotton for exploring its function in regulating plant defense to salt stress. The GaPPD2-overexpressed Arabidopsis thaliana plants significantly increased the tolerance to salt stress compared to the wild type in both medium and soil, while the GaPPD2-silenced cotton plants showed higher sensitivity to salt stress than the control in pots. The antioxidant activities experiment showed that GaPPD2 may mitigate the accumulation of reactive oxygen species by promoting superoxide dismutase accumulation, consequently improving plant resilience to salt stress. Through the exogenous application of MeJA (methy jasmonate) and the protein degradation inhibitor MG132, it was found that GaPPD2 functions in plant defense against salt stress and is involved in the JA signaling pathway. The RNA-seq analysis of GaPPD2-overexpressed A. thaliana plants and receptor materials showed that the differentially expressed genes were mainly enriched in antioxidant activity, peroxidase activity, and plant hormone signaling pathways. qRT-PCR results demonstrated that GaPPD2 might positively regulate plant defense by inhibiting GH3.2/3.10/3.12 expression and activating JAZ7/8 expression. The findings highlight the potential of GaPPD2 as a JA signaling component gene for improving the cotton plant resistance to salt stress and provide insights into the mechanisms underlying plant responses to environmental stresses.

An alternative 3' splice site of PeuHKT1;3 improves the response to salt stress through enhancing affinity to K+ in Populus

Alternative splicing (AS) serves as a crucial post-transcriptional regulator in plants that contributes to the resistance to salt stress. However, the underlying mechanism is largely unknown. In this research, we identified an important AS transcript in Populus euphratica, PeuHKT1:3a, generated by alternative 3' splice site splicing mode that resulted in the removal of 252 bases at the 5' end of the first exon in PeuHKT1:3. Protein sequence comparison showed that the site of AS occurred in PeuHKT1:3 is located at a crucial Ser residue within the first pore-loop domain, which leads to inefficient K+ transport in HKT I-type transporters. Expressing PeuHKT1;3a in an axt3 mutant yeast strain can effectively compensate for the lack of intracellular K+, whereas the expression of PeuHKT1;3 cannot yield the effect. Furthermore, in transgenic Arabidopsis and poplar plants, it was observed that lines expressing PeuHKT1;3a exhibited greater salt tolerance compared to those expressing the PeuHKT1;3 strain. Analysis of ion content and flux demonstrated that the transgenic PeuHKT1;3a line exhibited significantly higher K+ content compared to the PeuHKT1;3 line, while there was no significant difference in Na+ content. In conclusion, our findings revealed that AS can give rise to novel variants of HKT I-type proteins in P. euphratica with modified K+ selectivity to keep a higher K+/Na+ ratio to enhanced salt tolerance.

Functional Identification of Malus halliana MhbZIP23 Gene Demonstrates That It Enhances Saline-Alkali Stress Tolerance in Arabidopsis thaliana

Saline-alkali stress is a significant abiotic stress that restricts plant growth globally. Basic region leucine zipper (bZIP) transcription factor proteins are widely involved in plants in response to abiotic stress such as saline-alkali stress. Based on transcriptome and quantitative real-time PCR (qRT-PCR), we found that the MhbZIP23 gene could respond to saline-alkali stress. Despite this discovery, the underlying mechanism by which the MhbZIP23 transcription factor responds to saline-alkaline stress remains unexplored. To address this gap in knowledge, we successfully cloned the MhbZIP23 (MD05G1121500) gene from Malus halliana for heterologous expression in Arabidopsis thaliana, facilitating the investigation of its functional role in stress response. Compared to the wild type (WT), Arabidopsis plants demonstrated enhanced growth and a lower degree of wilting when subjected to saline-alkali stress. Furthermore, several physiological indices of the plants altered under such stress conditions. The transgenic Arabidopsis plants (OE-5, 6, and 8), which grew normally, exhibited a higher chlorophyll content and had greater root length in comparison to the control check (CK). MhbZIP23 effectively regulated the levels of the osmoregulatory substance proline (Pro), enhanced the activities of antioxidant enzymes such as peroxidase (POD) and superoxide dismutase (SOD), and reduced the levels of malondialdehyde (MDA) and relative conductivity (REC). These actions improved the ability of plant cells in transgenic Arabidopsis to counteract ROS, as evidenced by the decreased accumulation of O2- and hydrogen peroxide (H2O2). In summary, the MhbZIP23 gene demonstrated effectiveness in alleviating saline-alkali stress in M. halliana, presenting itself as an outstanding resistance gene for apples to combat saline-alkali stress.

Exogenous Eugenol Alleviates Salt Stress in Tobacco Seedlings by Regulating the Antioxidant System and Hormone Signaling

Salt stress seriously affects crop growth, leading to a decline in crop quality and yield. Application of exogenous substances to improve the salt tolerance of crops and promote their growth under salt stress has become a widespread and effective means. Eugenol is a small molecule of plant origin with medicinal properties such as antibacterial, antiviral, and antioxidant properties. In this study, tobacco seedlings were placed in Hoagland's solution containing NaCl in the presence or absence of eugenol, and physiological indices related to stress tolerance were measured along with transcriptome sequencing. The results showed that eugenol improved the growth of tobacco seedlings under salt stress. It promoted carbon and nitrogen metabolism, increased the activities of nitrate reductase (NR), sucrose synthase (SS), and glutamine synthetase (GS) by 31.03, 5.80, and 51.06%. It also activated the enzymatic and non-enzymatic antioxidant systems, reduced the accumulation of reactive oxygen species in the tobacco seedlings, and increased the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) by 24.38%, 18.22%, 21.60%, and 28.8%, respectively. The content of glutathione (GSH) was increased by 29.49%, and the content of superoxide anion (O2-) and malondialdehyde (MDA) were reduced by 29.83 and 33.86%, respectively. Promoted osmoregulation, the content of Na+ decreased by 34.34, K+ increased by 41.25%, and starch and soluble sugar increased by 7.72% and 25.42%, respectively. It coordinated hormone signaling in seedlings; the content of abscisic acid (ABA) and gibberellic acid 3 (GA3) increased by 51.93% and 266.28%, respectively. The transcriptome data indicated that the differentially expressed genes were mainly enriched in phenylpropanoid biosynthesis, the MAPK signaling pathway, and phytohormone signal transduction pathways. The results of this study revealed the novel role of eugenol in regulating plant resistance and provided a reference for the use of exogenous substances to alleviate salt stress.

Phenotype, Biomass, Carbon and Nitrogen Assimilation, and Antioxidant Response of Rapeseed under Salt Stress

Salt stress is one of the major adverse factors affecting plant growth and crop production. Rapeseed is an important oil crop, providing high-quality edible oil for human consumption. This experiment was conducted to investigate the effects of salt stress on the phenotypic traits and physiological processes of rapeseed. The soil salinity was manipulated by setting three different levels: 0 g NaCl kg-1 soil (referred to as S0), 1.5 g NaCl kg-1 soil (referred to as S1), and 3.0 g NaCl kg-1 soil (referred to as S2). In general, the results indicated that the plant height, leaf area, and root neck diameter decreased with an increase in soil salinity. In addition, the biomass of various organs at all growth stages decreased as soil salinity increased from S0 to S2. The increasing soil salinity improved the distribution of biomass in the root and leaf at the seedling and flowering stages, indicating that rapeseed plants subjected to salt stress during the vegetative stage are capable of adapting their growth pattern to sustain their capacity for nutrient and water uptake, as well as leaf photosynthesis. However, as the soil salinity increased, there was a decrease in the distribution of biomass in the pod and seed at the maturity stage, while an increase was observed in the root and stem, suggesting that salt stress inhibited carbohydrate transport into reproductive organs. Moreover, the C and N accumulation at the flowering and maturity stages exhibited a reduction in direct correlation with the increase in soil salinity. High soil salinity resulted in a reduction in the C/N, indicating that salt stress exerted a greater adverse effect on C assimilation compared to N assimilation, leading to an increase in seed protein content and a decrease in oil content. Furthermore, as soil salinity increased from S0 to S2, the activity of superoxide dismutase (SOD) and catalase (CAT) and the content of soluble protein and sugar increased by 58.39%, 33.38%, 15.57%, and 13.88% at the seedling stage, and 38.69%, 22.85%, 12.04%, and 8.26% at the flowering stage, respectively. In summary, this study revealed that salt stress inhibited C and N assimilation, leading to a suppressed phenotype and biomass accumulation. The imbalanced C and N assimilation under salt stress contributed to the alterations in the seed oil and protein content. Rapeseed had a certain degree of salt tolerance by improving antioxidants and osmolytes.

The Role of Plant Ubiquitin-like Modifiers in the Formation of Salt Stress Tolerance

The climate-driven challenges facing Earth necessitate a comprehensive understanding of the mechanisms facilitating plant resilience to environmental stressors. This review delves into the crucial role of ubiquitin-like modifiers, particularly focusing on ATG8-mediated autophagy, in bolstering plant tolerance to salt stress. Synthesising recent research, we unveil the multifaceted contributions of ATG8 to plant adaptation mechanisms amidst salt stress conditions, including stomatal regulation, photosynthetic efficiency, osmotic adjustment, and antioxidant defence. Furthermore, we elucidate the interconnectedness of autophagy with key phytohormone signalling pathways, advocating for further exploration into their molecular mechanisms. Our findings underscore the significance of understanding molecular mechanisms underlying ubiquitin-based protein degradation systems and autophagy in salt stress tolerance, offering valuable insights for designing innovative strategies to improve crop productivity and ensure global food security amidst increasing soil salinisation. By harnessing the potential of autophagy and other molecular mechanisms, we can foster sustainable agricultural practices and develop stress-tolerant crops resilient to salt stress.

Metabolomics analysis reveals enhanced salt tolerance in maize through exogenous Valine-Threonine-Isoleucine-Aspartic acid application

Salt stress is a well-known abiotic constraint that hampers crop productivity, affecting more than 424 million hectares of topsoil worldwide. Applying plant growth regulators externally has proven effective in enhancing crop resilience to salt stress. Previous metabolomics studies revealed an accumulation of Valine-Threonine-Isoleucine-Aspartic acid (VTID) in salt-stressed maize seedlings, suggesting its potential to assist maize adaptation to salt stress. To explore the effectiveness of VTID in enhancing salt tolerance in maize, 10 nM VTID was applied to salt-stressed maize seedlings. The results showed a remarkable 152.29% increase in plant height and a 122.40% increase in fresh weight compared to salt-stressed seedlings. Moreover, the addition of VTID enhanced the activity of antioxidant enzymes, specifically superoxide dismutase (SOD) and catalase (CAT), while reducing the level of malondialdehyde (MDA), a marker of oxidative stress. Additionally, VTID supplementation resulted in a significant increase in osmoregulatory substances such as proline. Metabolomic analysis revealed substantial changes in the metabolite profile of maize seedlings when treated with VTID during salt stress. Differential metabolites (DMs) analysis revealed that the identified DMs primarily belonged to lipids and lipid-like molecules. The receiver operating characteristic curve and linear regression analysis determined a correlation between isodolichantoside and the height of maize seedlings under salt-stress conditions. In conclusion, these findings validate that VTID effectively regulates tolerance in maize seedlings and offers valuable insights into the potential of short peptides for mitigating salt stress.

Seed germination demonstrates inter-annual variations in alkaline tolerance: a case study in perennial Leymus chinensis

BACKGROUND AND AIMS

The escalating issue of soil saline-alkalization poses a growing global challenge. Leymus chinensis is a perennial grass species commonly used in the establishment and renewal of artificial grasslands that is relatively tolerant of saline, alkaline, and drought conditions. Nonetheless, reduced seed setting rates limit its propagation, especially on alkali-degraded grassland. Inter-annual variations have an important effect on seed yield and germination under abiotic stress, and we therefore examined the effect of planting year on seed yield components of L. chinensis.

METHODS

We grew transplanted L. chinensis seedlings in pots for two (Y2), three (Y3), or four (Y4) years and collected spikes for measurement of seed yield components, including spike length, seed setting rate, grain number per spike, and thousand seed weight. We then collected seeds produced by plants from different planting years and subjected them to alkaline stress (25 mM Na2CO3) for measurement of germination percentage and seedling growth.

RESULTS

The seed setting rate of L. chinensis decreased with an increasing number of years in pot cultivation, but seed weight increased. Y2 plants had a higher seed setting rate and more grains per spike, whereas Y4 plants had a higher thousand seed weight. The effects of alkaline stress (25 mM Na2CO3) on seed germination were less pronounced for the heavier seeds produced by Y4 plants. Na2CO3 caused a 9.2% reduction in shoot length for seedlings derived from Y4 seeds but a 22.3% increase in shoot length for seedlings derived from Y3 seeds.

CONCLUSIONS

Our findings demonstrate significant differences in seed yield components among three planting years of L. chinensis under pot cultivation in a finite space. Inter-annual variation in seed set may provide advantages to plants. Increased alkalinity tolerance of seed germination was observed for seeds produced in successive planting years.

Elucidating the role of exogenous melatonin in mitigating alkaline stress in soybeans across different growth stages: a transcriptomic and metabolomic approach

BACKGROUND

Soybean (Glycine max), a vital grain and oilseed crop, serves as a primary source of plant protein and oil. Soil salinization poses a significant threat to soybean planting, highlighting the urgency to improve soybean resilience and adaptability to saline stress. Melatonin, recently identified as a key plant growth regulator, plays crucial roles in plant growth, development, and responses to environmental stress. However, the potential of melatonin to mitigate alkali stress in soybeans and the underlying mechanisms remain unclear.

RESULTS

This study investigated the effects of exogenous melatonin on the soybean cultivar Zhonghuang 13 under alkaline stress. We employed physiological, biochemical, transcriptomic, and metabolomic analyses throughout both vegetative and pod-filling growth stages. Our findings demonstrate that melatonin significantly counteracts the detrimental effects of alkaline stress on soybean plants, promoting plant growth, photosynthesis, and antioxidant capacity. Transcriptomic analysis during both growth stages under alkaline stress, with and without melatonin treatment, identified 2,834 and 549 differentially expressed genes, respectively. These genes may play a vital role in regulating plant adaptation to abiotic stress. Notably, analysis of phytohormone biosynthesis pathways revealed altered expression of key genes, particularly in the ARF (auxin response factor), AUX/IAA (auxin/indole-3-acetic acid), and GH3 (Gretchen Hagen 3) families, during the early stress response. Metabolomic analysis during the pod-filling stage identified highly expressed metabolites responding to melatonin application, such as uteolin-7-O-(2''-O-rhamnosyl)rutinoside and Hederagenin-3-O-glucuronide-28-O-glucosyl(1,2)glucoside, which helped alleviate the damage caused by alkali stress. Furthermore, we identified 183 differentially expressed transcription factors, potentially playing a critical role in regulating plant adaptation to abiotic stress. Among these, the gene SoyZH13_04G073701 is particularly noteworthy as it regulates the key differentially expressed metabolite, the terpene metabolite Hederagenin-3-O-glucuronide-28-O-glucosyl(1,2)glucoside. WGCNA analysis identified this gene (SoyZH13_04G073701) as a hub gene, positively regulating the crucial differentially expressed metabolite of terpenoids, Hederagenin-3-O-glucuronide-28-O-glucosyl(1,2)glucoside. Our findings provide novel insights into how exogenous melatonin alleviates alkali stress in soybeans at different reproductive stages.

CONCLUSIONS

Integrating transcriptomic and metabolomic approaches, our study elucidates the mechanisms by which exogenous melatonin ameliorates the inhibitory effects of alkaline stress on soybean growth and development. This occurs through modulation of biosynthesis pathways for key compounds, including terpenes, flavonoids, and phenolics. Our findings provide initial mechanistic insights into how melatonin mitigates alkaline stress in soybeans, offering a foundation for molecular breeding strategies to enhance salt-alkali tolerance in this crop.

A high-affinity potassium transporter (MeHKT1) from cassava (Manihot esculenta) negatively regulates the response of transgenic Arabidopsis to salt stress

BACKGROUND

High-affinity potassium transporters (HKTs) are crucial in facilitating potassium uptake by plants. Many types of HKTs confer salt tolerance to plants through regulating K+ and Na+ homeostasis under salinity stress. However, their specific functions in cassava (Manihot esculenta) remain unclear.

RESULTS

Herein, an HKT gene (MeHKT1) was cloned from cassava, and its expression is triggered by exposure to salt stress. The expression of a plasma membrane-bound protein functions as transporter to rescue a low potassium (K+) sensitivity of yeast mutant strain, but the complementation of MeHKT1 is inhibited by NaCl treatment. Under low K+ stress, transgenic Arabidopsis with MeHKT1 exhibits improved growth due to increasing shoot K+ content. In contrast, transgenic Arabidopsis accumulates more Na+ under salt stress than wild-type (WT) plants. Nevertheless, the differences in K+ content between transgenic and WT plants are not significant. Additionally, Arabidopsis expressing MeHKT1 displayed a stronger salt-sensitive phenotype.

CONCLUSION

These results suggest that under low K+ condition, MeHKT1 functions as a potassium transporter. In contrast, MeHKT1 mainly transports Na+ into cells under salt stress condition and negatively regulates the response of transgenic Arabidopsis to salt stress. Our results provide a reference for further research on the function of MeHKT1, and provide a basis for further application of MeHKT1 in cassava by molecular biological means.

Absorption and translocation of selected pharmaceuticals in Pistia stratiotes: Spatial distribution analysis using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Phytoremediation can eliminate pharmaceuticals from aquatic environments through absorption; however, understanding of absorption and transport processes in plants remains limited. In this study, a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry imaging (MALDI-MSI) method was developed to explore the absorption and translocation mechanisms of seven common pharmaceuticals in Pistia stratiotes. Results showed that 2,3-dicyanohydroquinone, an infrequently used matrix, exhibited outstanding performance in MALDI-MSI analysis, producing the highest signal intensity for four of the seven pharmaceuticals. Region of Interest (ROI) analysis revealed that charge speciation of pharmaceuticals significantly influenced their ability to enter vascular bundle. Neutral and positively charged pharmaceuticals easily entered vascular bundle, while negatively charged pharmaceuticals faced difficulty. ROI results for neutral and negatively charged pharmaceuticals exhibited positive correlation with their transfer factor values, indicating that their translocation ability from root to shoot was related to their capacity to enter vascular bundle. However, no correlation was observed for positively charged pharmaceuticals, suggesting that these compounds, upon entering vascular bundle, encountered difficulties in upward translocation through the xylem. This study introduces an innovative approach and offers novel insights into the retention and migration of pharmaceuticals in plant tissues, aiming to enhance the understanding of pharmaceutical accumulation in plants. ENVIRONMENTAL IMPLICATION: Pharmaceuticals in aquatic environment can inflict detrimental effects on both human health and ecosystem. Phytoremediation can remove pharmaceuticals from aquatic environments through absorption. However, our understanding of absorption and transportation of pharmaceuticals in plants remains limited. This study developed a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry imaging (MALDI-MSI) method for pharmaceuticals in plant roots, and to explore the absorption and translocation mechanisms of pharmaceuticals. The study offers direct evidence of differences in accumulation behavior of pharmaceuticals in plants, providing valuable insights for targeted and effective strategies in using plants for remediating the aquatic ecosystem from pharmaceuticals.