Effects of Salt Stress on the Morphology, Growth and Physiological Parameters of Juglansmicrocarpa L. Seedlings

Growth of soybean plants under saline conditions: the role of potassium and Bradyrhizobium japonicum inoculation

This study aimed to evaluate the effects of potassium (K) and Bradyrhizobium japonicum applications on physiological and microbial parameters in soybean plants under salt stress. The study included treatments of control, potassium (2.2 g K2SO4), bacteria (B), and their combinations (K + B), along with versions exposed to 100 mM NaCl salt stress. Key parameters such as leaf water content (RWC), chlorophyll (SPAD, Chlo a/b), oxidative stress indicators (H2O2 and MDA), proline, protein, antioxidant enzyme activities (APX, POD, and CAT), microbial biomass carbon (MBC), and CO2 release from soil were measured. Salt stress reduced RWC in plants by 15%, while H2O2 and MDA levels increased by 25% and 30%, respectively. However, potassium and bacterial applications improved plant resilience against stress by increasing proline levels by 20%, reducing protein loss by 18%, and enhancing antioxidant enzyme activities to mitigate oxidative damage. In soil microbial activities, MBC increased by up to 161%, and CO₂ release increased by up to 27.7% with K + B application. Under salt stress, MBC and CO₂ release were restored by 122% and 50.8%, respectively, demonstrating the positive effects of potassium and bacterial inoculation on microbial activity. These findings suggest that potassium and Bradyrhizobium japonicum applications could be considered effective strategies for enhancing plant tolerance and soil health under salt stress conditions.

NAC transcription factors as biological macromolecules responded to abiotic stress: A comprehensive review

NAC transcription factors (NAC TFs) represent a large and vital family of transcription factors in the plant kingdom, playing a central role in regulating plant growth, developmental processes, and responses to abiotic stresses. As key regulators, NAC TFs fine-tune the expression of downstream genes, thereby actively contributing to the adaptation of crops to various abiotic stresses. The functions of NAC TFs are controlled by several complex signaling pathways, including those involving phytohormones (such as abscisic acid (ABA) and ethylene (ET)), reactive oxygen species (ROS), and mitogen-activated protein kinases (MAPKs). This review highlights recent advances in the biological functions and signaling pathways of NAC TFs in crops under abiotic stress conditions, such as drought, salinity, and extreme temperatures. It also offers prospects for further exploration of the complex mechanisms by which NAC TFs operate within signaling networks, with the aim of developing food crops with enhanced physiological traits.

BEL1-like homeodomain transcription factor SAWTOOTH1 (MdSAW1) in Malus domestica enhances the tolerance of transgenic apple and Arabidopsis to zinc excess stress

In recent years, the phenomenon of zinc pollution in orchards has become increasingly serious, and the safety of apple production is facing a major risk. Therefore, exploring excellent genes for zinc tolerance has a positive effect on apples. Up to now, there is still a lack of attention on genes related to zinc stress tolerance in apples. In this study, the apple transcriptome map under zinc stress (1000 μM ZnSO4) was generated based on high-throughput sequencing. Through transcription factor analysis and association network prediction, TALE superfamily SAWTOOTH 1 was found to have an important role in 32 up-regulated core transcription factors. Further, BEL1-like homeodomain MdSAW1 gene from Malus domestica was overexpressed in Arabidopsis seedlings ('Col-0'), apple callus tissues ('Orin'), and apple plants ('GL-3'), and the results showed that the transformed lines carried obvious tolerance to zinc stress, which was reflected in the significant reduction of relative dielectric leakage, malondialdehyde, O2- and H2O2 content. The interaction between protein and DNA confirmed that MdSAW1 binds to natural resistance-associated macrophage protein NRAMP2 promoter to inhibit its transcription and thus regulate zinc ion homeostasis. In addition, overexpression of MdSAW1 increased the activity of antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase) and caused differences in metabolites in plants. MdSAW1 endows plants with strong tolerance to Zn stress, therefore, this study provides valuable reference for genetic improvement and environmental adaptation of fruit trees.

Genetic Diversity Assessment and Core Germplasm Screening of Blackcurrant (Ribes nigrum) in China via Expressed Sequence Tag-Simple Sequence Repeat Markers

Blackcurrant (Ribes nigrum L.) has high nutritional value for human health due to its abundant vitamin C, flavonoids, and organic acids. However, its breeding and genetic research have been severely hindered by the lack of scientific tools such as molecular markers. Here, we identified 14,258 EST-SSR loci from 9531 CDS sequences with lengths greater than 1 kb, which comprised 6211 mononucleotide repeats, 4277 dinucleotide repeats, and 2469 trinucleotide repeats. We then randomly selected 228 EST-SSR loci for PCR amplification and gel electrophoresis imaging in the Ribes collection of Northeast Agricultural University (95 blackcurrant cultivars and 12 other Ribes accessions). As a result, 31 pairs of markers produced clear and reproducible bands of the expected size. Based on the 107 Ribes accessions, the allele number (Na), information index (I), observed heterozygosity (Ho), expected heterozygosity (He), and polymorphic information content (PIC) of the 31 markers were 2-5, 0.23-1.32, 0.07-0.71, 0.11-0.68, and 0.14-0.67, respectively. For the blackcurrant gene pool, neighbor-joining and population structure analysis revealed three clusters, which did not align well with their geographical origins. Based on the results, two sets with 21 and 19 blackcurrant cultivars were identified by Power Core (PC) and Core Hunter (CH) programs. The integrated core germplasm (IC) set with 27 cultivars derived from the PC and CH sets harbored abundant genetic diversity, where the allele retention rate accounted for 98.9% of the blackcurrant gene pool. The SSR markers, data, and core germplasms presented in this study lay a solid foundation for the phylogenetic study, molecular breeding, and conservation genetics of Ribes, especially Ribes nigrum.

Exogenous sucrose alleviates salt stress in sunflower (Helianthus annuus L.) and canola (Brassica napus L.) by modulating osmotic adjustment and antioxidant defense system

Salinity, a major ecological problem worldwide, adversely affects plant growth and productivity. Osmoprotectants are a possible strategy for plants to cope with and regulate their response to unfavorable environmental conditions, such as salinity. However, the role of sucrose in this process requires more precise elucidation. This study aims to investigate the ameliorative role of sucrose on growth parameters, proline content, antioxidant enzyme activity, and gene expression in sunflower and canola under salt stress. The treatments included a 3% sucrose concentration and two levels of salinity (75 and 150 mM NaCl). Salinity caused a remarkable reduction in stem-root growth, chlorophyll amounts and catalase (CAT) activity, whereas it unchanged ascorbate peroxidase (APX) activity. Furthermore, both plants grown under salt stress had considerably higher total protein, proline, malondialdehyde (MDA) content, and superoxide dismutase (SOD) activity. Exogenous sucrose increased plant growth, chlorophyll amounts and the activities of hydrogen peroxide-detoxifying antioxidant enzymes such as CAT and APX in salt-stressed plants, but dramatically depressed levels of osmoregulators such as protein and proline. Besides that, it balanced antioxidant enzyme levels by regulating SOD activity to the required level, thereby facilitating the effective operation of the antioxidant defense system. Additionally, sucrose had a different effect on gene expressions of antioxidants in sunflower and canola under salinity. These results revealed that sucrose can ameliorate the deleterious effects of salinity in sunflower and canola by modulating osmotic substance accumulation, the activity of antioxidant enzymes, and their gene expression. In conclusion, sucrose can be a potential tool for plants in salt stress alleviation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-025-01571-9.

Exploration of the molecular mechanism behind a novel natural genic male-sterile mutation of 1205A in Brassica napus

The use of a male sterility hybrid seed production system has resulted in a significant increase in rapeseed yields by over 20%. Nevertheless, the mechanisms underlying male sterility remain largely unexamined. This study presents a spontaneous recessive genic male-sterile (RGMS) mutant of 1205A, which was employed to establish two two-line hybrid production systems: 1205AB and NT7G132AB. Cytological investigations reveal that the mutation occurs at the early microspore stage, resulting in premature degradation of pollen. Through inheritance analysis, linkage mapping, and bulked-segregant analysis sequencing (BSA-Seq), a single gene locus, designated Bna1205ams1, was identified within the QTL region on chrC03 (15.36-18.90 Mb). The development of three newly co-segregated kompetitive allele-specific PCR (KASP) markers, in conjunction with two traditional co-segregated markers, allowed for the refinement of the QTL of Bna1205ams1 to a segment of 181.47 kb. This refinement facilitated the identification of a candidate gene, BnaC03g27700D, through functional and expression analyses. Furthermore, the subcellular localization of BnaC03g27700D was examined. Metabolic fluctuations associated with the fertility gene were observed, particularly in processes related to aborted tapetal programmed cell death (PCD), which may contribute to reduced pollen fertility with abnormal pollen exine. A strong correlation was also established between BnaC03g27700D and thirteen metabolites. This study not only offers valuable insights into the research and practical application of plant male sterility but also serves as a case study on the genetic regulatory mechanisms governing male sterility.

Occurrence of antibiotics and antibiotic resistance genes at various stages of different aquaculture modes surrounding Tai Lake, China

Introduction

Aquaculture is an important source of antibiotics and ARGs in environmental waters. However, the occurrence of antibiotics and ARGs under different modes and stages of aquaculture has rarely been systematically studied.

Methods

This paper uses qPCR, LC-MS, and High-Throughput sequencing across different culture modes and stages to investigate antibiotics, resistance genes, and microbial communities in the water bodies, and analyze contamination differences between these modes.

Results

The quinolone and chloramphenicol were the main antibiotics, and the highest absolute abundance genes were quinolone resistance genes (qnrB) and quinolone resistance genes (sul1), with the mobile genetic element (MGE) intI1, both of which exhibited a gradual seasonal increase. Microbial diversity also varies seasonally, especially with a gradual increase in the abundance of some pathogenic bacteria (Flavobacterium). Antibiotics and resistance genes were found at higher levels in fish ponds compared to shrimp and crab ponds, while they were lower in shrimp and crab ponds that utilized the ecological mode ponds than in the traditional culture mode ponds.

Conclusion

Our study presents a comprehensive characterization of antibiotics and ARGs in aquaculture waters from various perspectives. Ecological aquaculture modes contribute to reducing antibiotic and resistance gene pollution in water bodies. These findings will support the optimization of aquaculture mode and antibiotic usage to the green and sustainable development of aquaculture finally.

Endophytic strategies decoded by genome and transcriptome analysis of Fusarium nematophilum strain NQ8GII4

Introduction

Fusarium nematophilum strain NQ8GII4 is an endophytic fungus with significant potential for improving growth and disease resistance of alfalfa. However, the molecular mechanisms underlying the symbiotic relationship between NQ8GII4 and alfalfa roots remain poorly understood.

Methods

In this study, we conducted (1) a comparative genomic analysis of selected saprophytic, pathogenic, and endophytic fungi, including molecular phylogeny analysis, whole-genome alignment, and divergence date estimation positioning, and (2) transcriptomic profiling of alfalfa roots infected with NQ8GII4.

Results

Our findings reveal that NQ8GII4 is genetically closely related to F. solani, suggesting it diverged from Fusarium phytopathogens. During the early stages of symbiosis establishment, genes encoding glycosyltransferases (GTs), fungal cell wall-degrading enzymes (FCWDEs), and steroid-14α-demethylase (CYP51) were significantly downregulated, potentially suppressing hyphal growth of the fungus. Once symbiosis was established, NQ8GII4 secreted effectors that activated plant immunity, which in turn could slow growth of the fungus. Moreover, genes involved in secondary metabolite biosynthesis, such as type I polyketide synthases (T1PKS) and non-ribosomal peptide synthetases (NRPSs), were significantly downregulated. Homologs of autophagy-related genes, including ATG1, ATG2, ATG11, and others, were also downregulated, suggesting that reduced phytotoxin production and autophagy inhibition is a consequence of NQ8GII4's symbiosis.

Discussion

This study investigated the comprehensive molecular and genetic mechanisms governing the interaction between NQ8GII4 and alfalfa roots. Beyond the NQ8GII4-alfalfa system, these findings also provide a valuable molecular framework for understanding the mechanism of interactions between endophytic fungi and their host plants.

Trade-Off Between Enzymatic Antioxidant Defense and Accumulation of Organic Metabolite Affects Salt Tolerance of White Clover Associated with Redox, Water, and Metabolic Homeostases

White clover (Trifolium repens) is an excellent perennial cold-season ground-cover plant for municipal landscaping and urban greening. It is, therefore, widely distributed and utilized throughout the world. However, poor salt tolerance greatly limits its promotion and application. This study aims to investigate the difference in the mechanism of salt tolerance in relation to osmotic adjustment, enzymatic and nonenzymatic antioxidant defenses, and organic metabolites remodeling between salt-tolerant PI237292 (Trp004) and salt-sensitive Korla (KL). Results demonstrated that salt stress significantly induced chlorophyll loss, water imbalance, and accumulations of malondialdehyde (MDA), hydrogen peroxide (H2O2), and superoxide anion (O2.-), resulting in reduced cell membrane stability in two types of white clovers. However, Trp004 maintained significantly higher leaf relative water content and chlorophyll content as well as lower osmotic potential and oxidative damage, compared with KL under salt stress. Although Trp004 exhibited significantly lower activities of superoxide dismutase, peroxidase, catalase, ascorbate peroxidase, monodehydroasorbate reductase, dehydroascorbate reductase, and glutathione reductase than KL in response to salt stress, significantly higher ascorbic acid (ASA), dehydroascorbic acid (DHA), glutathione (GSH), glutathione disulfide (GSSG), ASA/DHA, and GSH/GSSG were detected in Trp004. These findings indicated a trade-off relationship between antioxidant enzymes and nonenzymatic antioxidants in different white clover genotypes adapting to salt stress. In addition, Trp004 accumulated more organic acids (glycolic acid, succinic acid, fumaric acid, malic acid, linolenic acid, and cis-sinapic acid), amino acids (serine, l-allothreonine, and 4-aminobutyric acid), sugars (tagatose, fructose, glucoheptose, cellobiose, and melezitose), and other metabolites (myo-inositol, arabitol, galactinol, cellobiotol, and stigmasterol) than KL when they suffered from the same salt concentration and duration of stress. These organic metabolites helped to maintain osmotic adjustment, energy supply, reactive oxygen species homeostasis, and cellular metabolic homeostasis with regard to salt stress. Trp004 can be used as a potential resource for cultivating in salinized soils.

Comparative Transcriptomic Analysis and Candidate Gene Identification for Wild Rice (GZW) and Cultivated Rice (R998) Under Low-Temperature Stress

Rice is a short-day thermophilic crop that originated from the low latitudes of the tropics and subtropics; it requires high temperatures for growth but is sensitive to low temperatures. Therefore, it is highly important to explore and analyze the molecular mechanism of cold tolerance in rice to expand rice planting areas. Here, we report a phenotypic evaluation based on low-temperature stress in indica rice (R998) and wild rice (GZW) and a comparative transcriptomic study conducted at six time points. After 7 days of low-temperature treatment at 10 °C, R998 exhibited obvious yellowing and greening of the leaves, while GZW exhibited high low-temperature resistance, and the leaves maintained their normal morphology and exhibited no yellowing; GZW has a higher survival rate. Principal component analysis (PCA) and cluster analysis of the RNA-seq data revealed that the difference in low-temperature resistance between the two cultivars was caused mainly by the difference in low-temperature treatment after 6 h. Differential expression analysis revealed 2615 unique differentially expressed genes (DEGs) in the R998 material, 1578 unique DEGs in the GZW material, 1874 unique DEGs between R998 and GZW, and 2699 DEGs that were differentially expressed not only between cultivars but also at different time points in the same material under low-temperature treatment. A total of 15,712 DEGs were detected and were significantly enriched in the phenylalanine metabolism, photosynthesis, plant hormone signal transduction, and starch and sucrose metabolism pathways. These 15,712 DEGs included 1937 genes encoding transcription factors (TFs), of which 10 have been identified with functional validation in previous studies. In addition, a gene regulatory network was constructed via weighted gene correlation network analysis (WGCNA), and 12 key genes related to low-temperature tolerance in rice were identified, including five genes encoding TFs, one of which was identified and verified in previous studies. These results provide a theoretical basis for an in-depth understanding of the molecular mechanism of low-temperature tolerance in rice and provide new genetic resources for the study of low-temperature tolerance in rice.

Easily overlooked petiole traits are key factors that affect soil carbon sequestration in plantations in karst areas

Vegetation restoration in karst areas has shifted from expanding planting areas to the collective enhancement of various ecological functions, especially carbon sequestration. Identifying and regulating key plant functional traits involved in the carbon cycle is an effective approach to increase carbon sequestration. However, reports on the significant contribution of petiole traits to the carbon cycle are scarce. Eucalyptus globulus and Bauhinia purpurea plantations in Liujiang river basin were investigated in this study. Petiole traits, understory characteristics, and soil organic carbon have been measured. The aim is to explore key effect of petiole traits for increasing soil carbon sequestration and to provide scientific evidence for the high-quality development of plantations in karst areas. The results indicate that in Eucalyptus globulus plantations, when the understory vegetation coverage is below 50 %, petioles tend to elongate rather than thicken, leading to an increase in specific petiole length. In Bauhinia purpurea plantations, petioles consistently tend to increase diameter. However, when specific leaf area decreases, specific petiole length increases. In both plantations, an increase in specific petiole length accelerates leaf shedding. It leads to increased litter accumulation so that soil carbon content increases. In Eucalyptus globulus plantations, to enhance soil carbon sequestration as an ecological goal, it is recommended to keep the soil total nitrogen below 1.20 mg/g, to control understory vegetation coverage below 50 %, and to limit the extension of Bidens pilosa. In Bauhinia purpurea plantations, within 100 m of altitude, the soil total nitrogen can be controlled below 1.00 mg/g to increase soil organic carbon from large leaf shedding due to the increase of specific petiole length. At lower altitudes, increasing soil total nitrogen can enhance understory vegetation coverage, allowing soil organic carbon to originate from both leaf shedding and understory vegetation residues.

Effects of alkaline salt stress on growth, physiological properties and medicinal components of clonal Glechoma longituba (Nakai) Kupr

BACKGROUND

Glechoma longituba, recognized as a medicinal plant, provides valuable pharmaceutical raw materials for treating various diseases. Saline-alkali stress may effectively enhance the medicinal quality of G. longituba by promoting the synthesis of secondary metabolites. To investigate the changes in the primary medicinal components of G. longituba under saline-alkali stress and improve the quality of medicinal materials, Na2CO3 was applied to induce short-term stress under different conditions and the biomass, physiologically active substances and primary medicinal components of G. longituba were measured in this study.

RESULTS

Under alkaline salt stress, the activities of catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), and ascorbate peroxidase (APX) were elevated in G. longituba, accompanied by increased accumulation of proline (Pro) and malondialdehyde (MDA). Furthermore, analysis of the medicinal constituents revealed that G. longituba produced the highest levels of soluble sugars, flavonoids, ursolic acid, and oleanolic acid under 0.6% Na2CO3 stress for 48 h, 0.2% Na2CO3 stress for 72 h, 0.4% Na2CO3 stress for 12 h, and 0.4% Na2CO3 stress for 8 h, respectively.

CONCLUSIONS

Short-term Na2CO3 stress enhances the synthesis of medicinal components in G. longituba. By manipulating stress conditions, the production of various medicinal substances could be optimized. This approach may serve as a basis for the targeted cultivation of G. longituba, offering potential applications in the treatment of diverse diseases.

Genome-wide identification and comprehensive analysis of the AP2/ERF gene family in Prunus sibirica under low-temperature stress

BACKGROUND

AP2/ERF transcription factors are involved in the regulation of growth, development, and stress response in plants. Although the gene family has been characterized in various species, such as Oryza sativa, Arabidopsis thaliana, and Populus trichocarpa, studies on the Prunus sibirica AP2/ERF (PsAP2/ERF) gene family are lacking. In this study, PsAP2/ERFs in P. sibirica were characterized by genomic and transcriptomic analyses.

RESULTS

In the study, 112 PsAP2/ERFs were identified and categorized into 16 subfamilies. Within each subfamily, PsAP2/ERFs exhibited similar exon-intron structures and motif compositions. Additionally, 50 pairs of segmentally duplicated genes were identified within the PsAP2/ERF gene family. Our experimental results showed that 20 PsAP2/ERFs are highly expressed in leaves, roots, and pistils under low-temperature stress conditions. Among them, the expression of PsAP2/ERF21, PsAP2/ERF56 and PsAP2/ERF88 was significantly up-regulated during the treatment period, and it was hypothesised that members of the PsAP2/ERF family play an important role inlow temperature stress tolerance.

CONCLUSIONS

This study improves our understanding of the molecular basis of development and low-temperature stress response in P. sibirica and provides a solid scientific foundation for further functional assays and evolutionary analyses of PsAP2/ERFs.

Morphological, physiological, and biochemical responses of three different soybean (Glycine max L.) varieties under salinity stress conditions

Salinity is one of the most detrimental factors for the growth performance and productivity of crops worldwide. Therefore, understanding crop responses or growth potentials and their effectiveness in salinity mitigation is highly important for the selection of salinity-tolerant plant varieties. In this study, the effects of salinity at various stress levels (0 mM, 50 mM, 100 mM, and 150 mM NaCl) on the morphological, physiological, and biochemical parameters of three soybean varieties ('Afigat', 'Gishama', and 'Pawi-2') were investigated. The results showed that salinity significantly reduced morphological traits including plant height, number of leaves per plant, stem thickness, shoot and root length, and fresh and dry weight. This reduction was more prominent in the 'Afigat' variety for all of these traits except shoot and root length. The concentrations of chlorophyll a and b decreased with increasing salinity. In addition, salinity significantly increased leaf electrolyte leakage (EL), lipid peroxidation, proline accumulation, and phenol and flavonoid content. The 'Pawi-2' variety was more tolerant than the other studied varieties in terms of membrane stability (less EL and a low malondialdehyde content) and proline, phenol, and flavonoid accumulation. Therefore, 'Pawi-2' may be considered as the most salt-tolerant variety in comparison with the other studied soybean varieties. Further complementary studies in field conditions including anatomical parameters are needed to confirm these findings.

Pathogenic and Comparative Genomic Analysis of Ralstonia pseudosolanacearum Isolated from Casuarina

Casuarina equisetifolia is crucial in protecting coastal regions of China against typhoon attacks but has faced a substantial challenge due to wilt disease caused by pathogens of the Ralstonia solanacearum species complex (RSSC). Although the initial outbreak of Casuarina wilt in the 1970s was effectively controlled by disease-resistant C. equisetifolia varieties, the disease has recently re-emerged in coastal regions of Guangdong. In this study, we report the isolation, characterization, and comparative genomic analysis of 11 RSSC strains from diseased C. equisetifolia at various locations along the coast of Guangdong. Phylogenomic analysis showed that the strains were closely related and clustered with phylotype I strains previously isolated from peanuts. Single-gene-based analysis further suggested these strains could be derived from strains present in Guangdong since the 1980s, indicating a historical context to their current pathogenicity. Casuarina-isolated strains exhibited notably higher virulence against C. equisetifolia and peanuts than the representative RSSC strains GMI1000 and EP1, suggesting host-specific adaptations that possibly contributed to the recent outbreak. Comparative genomic analysis among RSSC strains revealed a largely conserved genome structure and high levels of conservation in gene clusters encoding extracellular polysaccharide biosynthesis, secretion systems, and quorum sensing regulatory systems. However, we also found a number of unique genes in the Casuarina-isolated strains that were absent in GMI1000 and EP1, and vice versa, pointing to potential genetic factors underpinning their differential virulence. These unique genes offer promising targets for future functional studies. Overall, our findings provide crucial insights into the RSSC pathogens causing Casuarina wilt in Guangdong, guiding future efforts in disease control and prevention.

Analysis of Metabolic Profiles and Antioxidant Activity of Chinese Cordyceps, Ophiocordyceps sinensis, and Paecilomyces hepiali Based on Untargeted Metabolomics

Chinese cordyceps (GL) is a traditional medicinal fungus, with Ophiocordyceps sinensis (O. sinensis, BL) and Paecilomyces hepiali (P. hepiali, JSB) being fungi isolated from wild Chinese cordyceps. These three species share similar chemical composition and pharmacological effects. Existing studies have primarily compared the metabolites of Chinese cordyceps and O. sinensis, overlooking the assessment of antioxidant capacity in Chinese cordyceps, P. hepiali, and O. sinensis. In this study, LC-MS/MS was employed to analyze metabolites in GL, JSB, and BL. Utilizing principal component analysis (PCA), supervised orthogonal partial least squares discriminant analysis (OPLS-DA), and hierarchical cluster analysis (HCA), it was observed that the majority of differential metabolites (DMs) primarily accumulated in organic acids and derivatives, lipids and lipid-like molecules, and organoheterocyclic compounds. Antioxidant activity analysis indicated that GL exhibited the higher 2,2-diphenyl-1-picrylhydrazyl radical scavenging ability (DPPH•, scavenging rate is 81.87 ± 0.97%), hydroxyl free radical scavenging capacity (•OH, scavenging rate is 98.10 ± 0.60%), and superoxide anion radical scavenging capacity (O2•-, scavenging rate is 69.74 ± 4.36%), while JSB demonstrated the higher FRAP total antioxidant capacity of 8.26 μmol Trolox/g (p < 0.05). Correlation analysis revealed a positive correlation between DMs (fatty acyls and amino acids) and DPPH•, FRAP, •OH, and O2•- (p < 0.05). Additionally, glycerophospholipid DMs were found to be positively correlated with FRAP (p < 0.05). Through KEGG pathway analysis, it was determined that the accumulation of DMs in pathways such as cutin, suberine and wax biosynthesis has a higher impact on influencing the antioxidant activity of the samples. These results shed light on the antioxidant capacity and metabolic characteristics of Chinese cordyceps and its substitutes and offer valuable insights into how different DMs impact the strength of antioxidant activity, aiding in the advancement and application of Chinese cordyceps and its substitutes.

Biochar derived from olive oil pomace mitigates salt stress on seedling growth of forage pea

Studies are being conducted to develop strategies to reduce the adverse effects of salinity stress. In the present study, it was aimed to determine the interactive effects of salinity stress with biochar on plant growth-the physiological and biochemical attributes of forage peas (Pisum sativum ssp. arvense L.). Salt applications were carried out with irrigation water at concentrations of 0, 25, 50, 75, and 100 mM NaCl. The experiment was conducted using a randomized complete block design with three applications [control: 0 (B0), 2.5% biochar (B1), and 5% biochar (B2)], five salt doses [0 (S0), 25 (S1), 50 (S2), 75 (S3), and 100 (S4) mM NaCl], and three replications, arranged in a 3 × 5 factorial arrangement. In the salt-stressed environment, the highest plant height (18.75 cm) and stem diameter (1.71 mm) in forage pea seedlings were obtained with the application of B1. The root fresh (0.59 g/plant) and dry weight (0.36 g/plant) were determined to be the highest in the B1 application, both in non-saline and saline environments. A decrease in plant chlorophyll content in forage pea plants was observed parallel to the increasing salt levels. Specifically, lower H2O2, MDA, and proline content were determined at all salt levels with biochar applications, while in the B0 application these values were recorded at the highest levels. Furthermore, in the study, it was observed that the CAT, POD, and SOD enzyme activities were at their lowest levels at all salt levels with the biochar application, while in the B0 application, these values were determined to be at the highest levels. There was a significant decrease in plant mineral content, excluding Cl and Na, parallel to the increasing salt levels. The findings of the study indicate that biochar amendment can enhance forage peas' growth by modulating the plant physiology and biochemistry under salt stress. Considering the plant growth parameters, no significant difference was detected between 2.5% and 5% biochar application. Therefore, application of 2.5 biochar may be recommended.

Response of dissolved inorganic carbon dynamics to simulated tidal hydrological processes in coastal wetlands

To clarify the impacts of tidal hydrological process shifts caused by sea level rise on the blue carbon cycle, a typical coastal wetland in Jiaozhou Bay was selected for this study. The soils of Suaeda salsa (SS) and Phragmites australis (PA) wetlands were collected to simulate the effects of three types of tidal hydrological processes (Neap tide group, NT; Middle tide group, MT; Spring tide group, ST) on the soil-water dissolved inorganic carbon (DIC) dynamic. The results showed that the concentration of water dissolved inorganic carbon (WDIC) increased rapidly (115% higher) at early stage (days 0-4) under the influence of the tidal hydrological processes. Significant differences were found in WDIC concentration during different tidal hydrological processes (P < 0.05), which were expressed as MT (52.7 ± 13.3 mg L-1) > ST (52.5 ± 12.9 mg L-1) > NT (48.4 ± 10.1 mg L-1). After experiencing the tidal hydrological processes, the soil DIC content showed a net accumulation (55.1 ± 1.29 mg L-1vs. 46.7 ± 1.76 mg L-1, P < 0.001), whereas the soil inorganic carbon (SIC) decreased (2.73 ± 1.64 mg L-1vs. 4.61 ± 1.71 mg L-1), which may be attributed to the dissolution of SIC caused by the uptake of CO2 to form DIC. The accumulation of soil DIC was directly related to the SIC (λ = 1.03, P < 0.01), and indirectly related to soil nutrients (SOC substrate, λ = -0.003) and microbes (microbial biomass, λ = -0.10), and was mainly dominated by abiotic processes (abiotic: 58.1 ± 1.8% to 82.7 ± 2.46% vs. biotic: 17.4 ± 2.46% to 41.9 ± 1.76%). The increase of tidal frequency generally inhibited the accumulation of soil DIC content and promoted the output of WDIC. However, the response of soil DIC in different wetland types to tidal frequency was divergent, which was mainly regulated by the trade-off between soil nutrients and SIC content. Taken together, tidal hydrological processes and their frequency changes reshaped DIC dynamics, promoted the dissolution of SIC and the potential uptake of CO2. These findings enhance the comprehension of the inorganic carbon cycle within coastal wetlands, particularly amidst the backdrop of climate change and the rising sea levels.

Deciphering the dual role of persistent luminescence materials: Toxicity and photoreception effects on rice development

Studies on the toxicity of micro- and nanomaterials in plants have primarily focused on their intrinsic effects. However, there is often oversight when considering the potential perceptual responses that plants may exhibit in response to these materials. In this investigation, we assessed the impact of three commercially available persistent luminescence materials (PLMs) that emit red, green, or blue light under various environmental conditions. We subjected rice (Oryza sativa L.), a short-day plant, to nine distinct treatments, including exposure to particles in isolation, their nocturnal afterglow, or a combination of both. We thoroughly examined rice seedling morphology, photosynthesis patterns, metabolite dynamics, and flowering gene expression to determine the biological responses of plants to these particles. These findings demonstrated that PLMs stably interact with rice, and their emitted afterglow precisely matches the perceptual bandwidth of rice photoreceptors. Notably, the nocturnal afterglow from the red and blue PLMs enhanced the vegetative growth of rice seedlings while inhibiting their reproductive development. The blue PLMs exhibited the most pronounced positive effects, while the red PLMs exhibited inhibitory effects. When exposed to a combination of red and blue PLMs, rice displays enhanced growth and development. The observed alterations in the expression patterns of genes responsible for flowering supported these effects. We concluded that PLMs influence rice growth and development due to their inherent properties and intermittent illumination during dark periods. Both factors collectively shape rice growth and development.

Physiological and Cellular Ultrastructural Responses of Isatis indigotica Fort. under Salt Stress

This study aimed to analyze the effects of salt stress on the growth physiology and plant-cell ultrastructure of Isatis indigotica Fort. (I. indigotica) to evaluate its adaptability under salt stress. The effects of different concentrations of salt (NaCl; 0, 25, and 300 mmol·L-1) on the agronomic traits, activities of related enzymes, ion balance, and mesophyll-cell ultrastructure of I. indigotica were studied in a controlled pot experiment. Results showed that compared with those of the control group, the aerial-part fresh weight, underground fresh weight, tiller number, root length, root diameter, plant height, and leaf area of salt-stressed I. indigotica increased at 25 mmol·L-1 and then decreased at 300 mmol·L-1. The changes in levels of superoxide dismutase, peroxidase, ascorbate peroxidase, and catalase showed a similar trend, with significant differences compared with control group. Salt stress altered the ion balance of I. indigotica, resulting in a significant increase in Na+ content and a significant decrease in K+ content. The contents of Ca2+ and Mg2+ changed to varying degrees. The analysis of the microstructure of the root showed that under salt treatment, the epidermal cells of the root significantly thickened and the diameter of the xylem decreased. The results of ultrastructural analysis of mesophylls showed that salt stress can cause cell-membrane contraction, cell-gap enlargement, disorder in the structures of chloroplasts and mitochondria, and an increase in the number of osmiophilic particles. These changes were aggravated by the increase in NaCl concentration. This study reveals the response of I. indigotica to salt stress and provides a basis for further study on the salt-tolerance mechanism of I. indigotica.

CsSHMT3 gene enhances the growth and development in cucumber seedlings under salt stress

Salt stress is one of the major factors limiting plant growth and productivity. Many studies have shown that serine hydroxymethyltransferase (SHMT) gene play an important role in growth, development and stress response in plants. However, to date, there have been few studies on whether SHMT3 can enhance salt tolerance in plants. Therefore, the effects of overexpression or silencing of CsSHMT3 gene on cucumber seedling growth under salt stress were investigated in this study. The results showed that overexpression of CsSHMT3 gene in cucumber seedlings resulted in a significant increase in chlorophyll content, photosynthetic rate and proline (Pro) content, and antioxidant enzyme activity under salt stress condition; whereas the content of malondialdehyde (MDA), superoxide anion (H2O2), hydrogen peroxide (O2·-) and relative conductivity were significantly decreased when CsSHMT3 gene was overexpressed. However, the content of chlorophyll and Pro, photosynthetic rate, and antioxidant enzyme activity of the silenced CsSHMT3 gene lines under salt stress were significantly reduced, while MDA, H2O2, O2·- content and relative conductivity showed higher level in the silenced CsSHMT3 gene lines. It was further found that the expression of stress-related genes SOD, CAT, SOS1, SOS2, NHX, and HKT was significantly up-regulated by overexpressing CsSHMT3 gene in cucumber seedlings; while stress-related gene expression showed significant decrease in silenced CsSHMT3 gene seedlings under salt stress. This suggests that overexpression of CsSHMT3 gene increased the salt tolerance of cucumber seedlings, while silencing of CsSHMT3 gene decreased the salt tolerance. In conclusion, CsSHMT3 gene might positively regulate salt stress tolerance in cucumber and be involved in regulating antioxidant activity, osmotic adjustment, and photosynthesis under salt stress. KEY MESSAGE: CsSHMT3 gene may positively regulate the expression of osmotic system, photosynthesis, antioxidant system and stress-related genes in cucumber.

Creating Climate-Resilient Crops by Increasing Drought, Heat, and Salt Tolerance

Over the years, the changes in the agriculture industry have been inevitable, considering the need to feed the growing population. As the world population continues to grow, food security has become challenged. Resources such as arable land and freshwater have become scarce due to quick urbanization in developing countries and anthropologic activities; expanding agricultural production areas is not an option. Environmental and climatic factors such as drought, heat, and salt stresses pose serious threats to food production worldwide. Therefore, the need to utilize the remaining arable land and water effectively and efficiently and to maximize the yield to support the increasing food demand has become crucial. It is essential to develop climate-resilient crops that will outperform traditional crops under any abiotic stress conditions such as heat, drought, and salt, as well as these stresses in any combinations. This review provides a glimpse of how plant breeding in agriculture has evolved to overcome the harsh environmental conditions and what the future would be like.

Evaluation of Blue Honeysuckle Berries (Lonicera caerulea L.) Dried at Different Temperatures: Basic Quality, Sensory Attributes, Bioactive Compounds, and In Vitro Antioxidant Activity

This study aims to comprehensively investigate the effects of hot-air dehydration on the quality of blue honeysuckle berries (Lonicera caerulea L.). The results demonstrated that drying with hot air at 40-65 °C for 7-72 h resulted in blue honeysuckle berries with a moisture content of 0.21-1.10 g H2O/g dry weight. Generally, low to medium temperatures (40-55 °C) showed a better effect on the quality than high temperatures (60-65 °C). Specifically, drying at 40 °C exclusively resulted in better retention of cuticular wax, the best sensory appearance, and the highest total phenolic content. Drying at 45 °C and 50 °C resulted in the highest antioxidant capacity and the optimal sensory flavor. Drying at 55 °C led to the highest soluble solid/acid ratio, ascorbic acid concentration, total flavonoid, and total anthocyanin. The work introduces an innovative raw berry product and provides a comprehensive practical and theoretical framework for convective dehydration of blue honeysuckle berries.

Phenotypic heterogeneity unveils a negative correlation between antibiotic resistance and quorum sensing in Pseudomonas aeruginosa clinical isolates

Colonization of Pseudomonas aeruginosa in the lung environments frequently leads to the enrichment of strains displaying enhanced antibiotic resistance and reduced production of quorum-sensing (QS) controlled products. However, the relationship between the emergence of QS deficient variants and antibiotic resistance remains less understood. In this study, 67 P. aeruginosa strains were isolated from the lungs of 14 patients with chronic obstructive pulmonary disease, followed by determining their genetic relationship, QS-related phenotypes and resistance to commonly used antibiotics. The integrity of P. aeruginosa QS system was checked by DNA sequencing. The relationship between the QS system and antibiotic resistance was then assessed by correlation analyses. The function of the LasR protein and bacterial virulence were evaluated through homology modeling and nematode-infection assay. The influence of antibiotic on the development of extracellular protease production ability of P. aeruginosa was tested by an evolutionary experiment. The results showed that P. aeruginosa clinical strains displayed abundant diversity in phenotype and genotype. The production of extracellular proteases was significantly negatively correlated with antibiotic resistance. The strains with enhanced antibiotic resistance also showed a notable overlap with the mutation of lasR gene, which is the core regulatory gene of P. aeruginosa QS system. Molecular docking and Caenorhabditis elegans infection assays further suggested that P. aeruginosa with impaired LasR protein could also have varying pathogenicity. Moreover, in vitro evolution experiments demonstrated that antibiotic-mediated selective pressure, particularly from Levofloxacin contributed to the emergence of extracellular protease-negative strains. Therefore, this study provides evidence for the connection of P. aeruginosa QS system and antibiotic resistance, and holds significance for developing targeted strategies to address antibiotic resistance and improving the management of antibiotic-resistant infections in chronic respiratory diseases.

Humic acids enhance salt stress tolerance associated with pyrroline 5-carboxylate synthetase gene expression and hormonal alteration in perennial ryegrass (Lolium perenne L.)

Humic acid (HA) has been used as an important component in biostimulant formulations to enhance plant tolerance to salt stress, but the mechanisms underlying are not fully understood. This study was to investigate the physiological and molecular mechanisms of HA's impact on salt stress tolerance in perennial ryegrass (Lolium perenne L.). The two types of HA were extracted from weathered coal samples collected from Wutai County (WTH) and Jingle County (JLH) of Shanxi Province, China. The grass seedlings subjected to salt stress (250 mM NaCl) were treated with HA solutions containing 0.01% WTH (W/V) or 0.05% JLH (W/V), respectively. The HA treatments improved leaf photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (Gs) and reduced leaf oxidative injury (lower malondialdehyde content) and Pro and intercellular CO2 concentrations in salt-stressed perennial ryegrass. The HA treatments also reversed the decline in antioxidative enzymes ascorbate peroxidase (APX), catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) activity and improved growth and anti-senescence hormones indole-3-acetic acid (IAA) and brassinosteroid (BR). The HA treatments reduced the relative expression of P5CS and its downstream products proline (Pro) and the stress defense hormones abscisic acid (ABA), salicylic acid (SA), jasmonic acid (JA), and polyamines (PA). The results of this study indicate that the application of HAs may improve salt stress tolerance by regulating P5CS gene expression related to osmotic adjustment and increasing the activity of antioxidant enzymes and anti-senescence hormones in perennial ryegrass.

Prolonged ecological changes can affect morphometrics and gene expression profile? Focusing on Hsp-70 and NLHS-induced Hsp-70 of Artemia urmiana

BACKGROUND

In recent years, many aquatic ecosystems, including Urmia Lake, have undergone severe ecological tensions. This lake, the largest natural habitat of the brine shrimp Artemia urmiana, has progressively desiccated and its salinity has dramatically increased over the last three decades. In the face of the long period environmental stresses, understanding the adaptation and ecological plasticity mechanisms is the most interesting challenges in genetic and applied ecology. These mechanisms may probably be driven by inducing expression of some genes involved in adaptation such as Hsp-70 and also adjusting morphological parameters. But they are yet to be understood. Hence, the present work aimed to study the mechanisms, along with testing the hypothesis that non-lethal heat shocked nauplii originating from drought period can evoke Hsp-70 expression more than those from rainy period.

METHODS

This study measured and analyzed morphometrical characters of adult male and female Artemia urmiana over three decades. Then, the influence of three-decade ecological crisis on Hsp-70 and non-lethal heat shock (NLHS)-induced Hsp-70 expression levels of nauplii of Artemia urmiana habiting Urmia Lake using Real-time PCR technique, based on cyst collections in 1994 (rainy period) to 2020 (drought period), was evaluated.

RESULTS

The morphometrics results showed that the morphological characters were significantly shrunk in 2020 compared to 1994 (CI 95%, p < 0.05). Furthermore, our results depicted that, Hsp-70 expression level was significantly upregulated in response to the prolonged ecological crisis, (CI 95%, P < 0.0001), and also interestingly, the nauplii exposed to longe-term ecological crisis (belong to 2020) were able to increase Hsp-70 expression more than other ones in response to environmental stressors including heat.

CONCLUSIONS

The present results showed the involvement of Hsp-70 in the adaptation of Artemia urmiana to long term ecological alteration at the cost of shrinking morphometric parameters.

The Roles of Calcineurin B-like Proteins in Plants under Salt Stress

Salinity stands as a significant environmental stressor, severely impacting crop productivity. Plants exposed to salt stress undergo physiological alterations that influence their growth and development. Meanwhile, plants have also evolved mechanisms to endure the detrimental effects of salinity-induced salt stress. Within plants, Calcineurin B-like (CBL) proteins act as vital Ca2+ sensors, binding to Ca2+ and subsequently transmitting signals to downstream response pathways. CBLs engage with CBL-interacting protein kinases (CIPKs), forming complexes that regulate a multitude of plant growth and developmental processes, notably ion homeostasis in response to salinity conditions. This review introduces the repercussions of salt stress, including osmotic stress, diminished photosynthesis, and oxidative damage. It also explores how CBLs modulate the response to salt stress in plants, outlining the functions of the CBL-CIPK modules involved. Comprehending the mechanisms through which CBL proteins mediate salt tolerance can accelerate the development of cultivars resistant to salinity.

Cloning of the Soybean GmNHL1 Gene and Functional Analysis under Salt Stress

When encountered in the soybean seedling stage, salt stress has serious impacts on plant growth and development. This study explores the role of the soybean NDR1/HIN1-like family gene GmNHL1 under salt stress. First, the GmNHL1 gene was successfully cloned, and bioinformatic analysis revealed multiple cis-acting elements which are related to adversity stress and involved in the oxidative response in the promoter region. Sub-cellular localization analysis indicated that the protein expressed by GmNHL1 was localized on the cell membrane. An over-expression vector of the target gene and a CRISPR/Cas9 gene-editing vector were constructed, and the recipient soybean variety Jinong 74 was genetically transformed using the Agrobacterium tumefaciens-mediated method. By analyzing the performance of the different plants under salt stress, the results showed that GmNHL1 was over-expressed in the T2 generation. The germination potential, germination rate, germination index, and vitality index of the strain were significantly higher than those of the recipient control JN74. Under salt stress conditions, the root microanatomical structure of the GmNHL1 over-expressing material remained relatively intact, and its growth was better than that of the recipient control JN74. Measurement of physiological and biochemical indicators demonstrated that, compared with the receptor control JN74, the malondialdehyde and O2- contents of the GmNHL1 over-expressing material were significantly reduced, while the antioxidant enzyme activity, proline content, and chlorophyll content significantly increased; however, the results for GmNHL1 gene-edited materials were the opposite. In summary, over-expression of GmNHL1 can improve the salt tolerance of plants and maintain the integrity of the root anatomical structure, thereby more effectively and rapidly reducing the accumulation of malondialdehyde and O2- content and increasing antioxidant enzyme activity. This reduces cell membrane damage, thereby improving the salt tolerance of soybean plants. These results help to better understand the mechanism of salt tolerance in soybean plants, laying a theoretical foundation for breeding new stress-resistant varieties of soybean.

Effects of Salinity Stress on Growth and Physiological Parameters and Related Gene Expression in Different Ecotypes of Sesuvium portulacastrum on Hainan Island

We conducted a study to examine the growth and physiological changes in 12 different ecotypes of Sesuvium portulacastrum collected from Hainan Island in China. These ecotypes were subjected to different concentrations (0, 200, 400, and 600 mmol/L) of sodium chloride (NaCl) salt stress for 14 days. We also analyzed the expression of metabolic genes related to stress response. Under low salt stress, indicators such as plant height in region K (0 mmol/L: 45% and highest at 200 mmol/L: 80%), internode length (0 mmol/L: 0.38, 200 mmol/L: 0.87, 400 mmol/L: 0.25, and 600 mmol/L: 1.35), as well as leaf area, relative water content, fresh weight, and dry weight exhibited an overall increasing trend with the increase in salt concentration. However, as the salt concentration increased, these indicators showed a decreasing trend. Proline and malondialdehyde contents increased with higher salt concentrations. When the NaCl concentration was 400 mmol/L, MDA content in the leaves was highest in the regions E (196.23%), F (94.28%), J (170.10%), and K (136.08%) as compared to the control group, respectively. Most materials demonstrated a significant decrease in chlorophyll a, chlorophyll b, and total chlorophyll content compared to the control group. Furthermore, the ratio of chlorophyll a to chlorophyll b (Rab) varied among different materials. Using principal component analysis, we identified three ecotypes (L from Xinglong Village, Danzhou City; B from Shuigoupo Village, Lingshui County; and J from Haidongfang Park, Dongfang City) that represented high, medium, and low salt tolerance levels, respectively, based on the above growth and physiological indexes. To further investigate the expression changes of related genes at the transcriptional level, we employed qRT-PCR. The results showed that the relative expression of SpP5CS1, SpLOX1, and SpLOX1 genes increased with higher salt concentrations, which corresponded to the accumulation of proline and malondialdehyde content, respectively. However, the relative expression of SpCHL1a and SpCHL1b did not exhibit a consistent pattern. This study contributes to our understanding of the salt tolerance mechanism in the true halophyte S. portulacastrum, providing a solid theoretical foundation for further research in this field.

Plants' Response Mechanisms to Salinity Stress

Soil salinization is a severe abiotic stress that negatively affects plant growth and development, leading to physiological abnormalities and ultimately threatening global food security. The condition arises from excessive salt accumulation in the soil, primarily due to anthropogenic activities such as irrigation, improper land uses, and overfertilization. The presence of Na⁺, Cl^-, and other related ions in the soil above normal levels can disrupt plant cellular functions and lead to alterations in essential metabolic processes such as seed germination and photosynthesis, causing severe damage to plant tissues and even plant death in the worst circumstances. To counteract the effects of salt stress, plants have developed various mechanisms, including modulating ion homeostasis, ion compartmentalization and export, and the biosynthesis of osmoprotectants. Recent advances in genomic and proteomic technologies have enabled the identification of genes and proteins involved in plant salt-tolerance mechanisms. This review provides a short overview of the impact of salinity stress on plants and the underlying mechanisms of salt-stress tolerance, particularly the functions of salt-stress-responsive genes associated with these mechanisms. This review aims at summarizing recent advances in our understanding of salt-stress tolerance mechanisms, providing the key background knowledge for improving crops' salt tolerance, which could contribute to the yield and quality enhancement in major crops grown under saline conditions or in arid and semiarid regions of the world.