Intraspecific diploidization of a halophyte root fungus drives heterosis.

How organisms respond to environmental stress is a key topic in evolutionary biology. This study focused on the genomic evolution of Laburnicola rhizohalophila, a dark-septate endophytic fungus from roots of a halophyte. Chromosome-level assemblies were generated from five representative isolates from structured subpopulations. The data revealed significant genomic plasticity resulting from chromosomal polymorphisms created by fusion and fission events, known as dysploidy. Analyses of genomic features, phylogenomics, and macrosynteny have provided clear evidence for the origin of intraspecific diploid-like hybrids. Notably, one diploid phenotype stood out as an outlier and exhibited a conditional fitness advantage when exposed to a range of abiotic stresses compared with its parents. By comparing the gene expression patterns in each hybrid parent triad under the four growth conditions, the mechanisms underlying growth vigor were corroborated through an analysis of transgressively upregulated genes enriched in membrane glycerolipid biosynthesis and transmembrane transporter activity. In vitro assays suggested increased membrane integrity and lipid accumulation, as well as decreased malondialdehyde production under optimal salt conditions (0.3 M NaCl) in the hybrid. These attributes have been implicated in salinity tolerance. This study supports the notion that hybridization-induced genome doubling leads to the emergence of phenotypic innovations in an extremophilic endophyte.

Differential gene expression of salt-tolerant alfalfa in response to salinity and inoculation by Ensifer meliloti.

BACKGROUND: Alfalfa (Medicago sativa L.) experiences many negative effects under salinity stress, which may be mediated by recurrent selection. Salt-tolerant alfalfa may display unique adaptations in association with rhizobium under salt stress. RESULTS: To elucidate inoculation effects on salt-tolerant alfalfa under salt stress, this study leveraged a salt-tolerant alfalfa population selected through two cycles of recurrent selection under high salt stress. After experiencing 120-day salt stress, mRNA was extracted from 8 random genotypes either grown in 0 or 8 dS/m salt stress with or without inoculation by Ensifer meliloti. Results showed 320 and 176 differentially expressed genes (DEGs) modulated in response to salinity stress or inoculation x salinity stress, respectively. Notable results in plants under 8 dS/m stress included upregulation of a key gene involved in the Target of Rapamycin (TOR) signaling pathway with a concomitant decrease in expression of the SNrK pathway. Inoculation of salt-stressed plants stimulated increased transcription of a sulfate-uptake gene as well as upregulation of the Lysine-27-trimethyltransferase (EZH2), Histone 3 (H3), and argonaute (AGO, a component of miRISC silencing complexes) genes related to epigenetic and post-transcriptional gene control. CONCLUSIONS: Salt-tolerant alfalfa may benefit from improved activity of TOR and decreased activity of SNrK1 in salt stress, while inoculation by rhizobiumstimulates production of sulfate uptake- and other unique genes.

Salt-tolerant plant growth-promoting bacteria as a versatile tool for combating salt stress in crop plants.

Soil salinization poses a great threat to global agricultural ecosystems, and finding ways to improve the soils affected by salt and maintain soil health and sustainable productivity has become a major challenge. Various physical, chemical and biological approaches are being evaluated to address this escalating environmental issue. Among them, fully utilizing salt-tolerant plant growth-promoting bacteria (PGPB) has been labeled as a potential strategy to alleviate salt stress, since they can not only adapt well to saline soil environments but also enhance soil fertility and plant development under saline conditions. In the last few years, an increasing number of salt-tolerant PGPB have been excavated from specific ecological niches, and various mechanisms mediated by such bacterial strains, including but not limited to siderophore production, nitrogen fixation, enhanced nutrient availability, and phytohormone modulation, have been intensively studied to develop microbial inoculants in agriculture. This review outlines the positive impacts and growth-promoting mechanisms of a variety of salt-tolerant PGPB and opens up new avenues to commercialize cultivable microbes and reduce the detrimental impacts of salt stress on plant growth. Furthermore, considering the practical limitations of salt-tolerant PGPB in the implementation and potential integration of advanced biological techniques in salt-tolerant PGPB to enhance their effectiveness in promoting sustainable agriculture under salt stress are also accentuated.

Assembly and comparative analysis of the complete mitochondrial and chloroplast genome of Cyperus stoloniferus (Cyperaceae), a coastal plant possessing saline-alkali tolerance.

BACKGROUND: Cyperus stoloniferus is an important species in coastal ecosystems and possesses economic and ecological value. To elucidate the structural characteristics, variation, and evolution of the organelle genome of C. stoloniferus, we sequenced, assembled, and compared its mitochondrial and chloroplast genomes. RESULTS: We assembled the mitochondrial and chloroplast genomes of C. stoloniferus. The total length of the mitochondrial genome (mtDNA) was 927,413 bp, with a GC content of 40.59%. It consists of two circular DNAs, including 37 protein-coding genes (PCGs), 22 tRNAs, and five rRNAs. The length of the chloroplast genome (cpDNA) was 186,204 bp, containing 93 PCGs, 40 tRNAs, and 8 rRNAs. The mtDNA and cpDNA contained 81 and 129 tandem repeats, respectively, and 346 and 1,170 dispersed repeats, respectively, both of which have 270 simple sequence repeats. The third high-frequency codon (RSCU > 1) in the organellar genome tended to end at A or U, whereas the low-frequency codon (RSCU < 1) tended to end at G or C. The RNA editing sites of the PCGs were relatively few, with only 9 and 23 sites in the mtDNA and cpDNA, respectively. A total of 28 mitochondrial plastid DNAs (MTPTs) in the mtDNA were derived from cpDNA, including three complete trnT-GGU, trnH-GUG, and trnS-GCU. Phylogeny and collinearity indicated that the relationship between C. stoloniferus and C. rotundus are closest. The mitochondrial rns gene exhibited the greatest nucleotide variability, whereas the chloroplast gene with the greatest nucleotide variability was infA. Most PCGs in the organellar genome are negatively selected and highly evolutionarily conserved. Only six mitochondrial genes and two chloroplast genes exhibited Ka/Ks > 1; in particular, atp9, atp6, and rps7 may have undergone potential positive selection. CONCLUSION: We assembled and validated the mtDNA of C. stoloniferus, which contains a 15,034 bp reverse complementary sequence. The organelle genome sequence of C. stoloniferus provides valuable genomic resources for species identification, evolution, and comparative genomic research in Cyperaceae.

Soil salinity regulates spatial-temporal heterogeneity of seed germination and seedbank persistence of an annual diaspore-trimorphic halophyte in northern China.

BACKGROUND AND AIMS: Seed heteromorphism is a plant strategy that an individual plant produces two or more distinct types of diaspores, which have diverse morphology, dispersal ability, ecological functions and different effects on plant life history traits. The aim of this study was to test the effects of seasonal soil salinity and burial depth on the dynamics of dormancy/germination and persistence/depletion of buried trimorphic diaspores of a desert annual halophyte Atriplex centralasiatica. METHODS: We investigated the effects of salinity and seasonal fluctuations of temperature on germination, recovery of germination and mortality of types A, B, C diaspores of A. centralasiatica in the laboratory and buried diaspores in situ at four soil salinities and three depths. Diaspores were collected monthly from the seedbank from December 2016 to November 2018, and the number of viable diaspores remaining (not depleted) and their germinability were determined. RESULTS: Non-dormant type A diaspores were depleted in the low salinity "window" in the first year. Dormant diaspore types B and C germinated to high percentages at 0.3 and 0.1 mol L-1 soil salinity, respectively. High salinity and shallow burial delayed depletion of diaspore types B and C. High salinity delayed depletion time of the three diaspore types and delayed dormancy release of types B and C diaspores from autumn to spring. Soil salinity modified the response of diaspores in the seedbank by delaying seed dormancy release in autum and winter and by providing a low-salt concentration window for germination of non-dormant diaspores in spring and early summer. CONCLUSIONS: Buried trimorphic diaspores of annual desert halophyte A. centralasiatica exhibited diverse dormancy/germination behavior in respond to seasonal soil salinity fluctuation. Prolonging persistence of the seedbank and delaying depletion of diaspores under salt stress in situ primarily is due to inhibition of dormancy-break. The differences in dormancy/germination and seed persistence in the soil seedbank may be a bet-hadging strategy adapted to stressful temporal and spatial heterogeneity, and allows A. centralasiatica to persist in the unpredictable cold desert enevironment.

Overexpression of GhGSTF9 Enhances Salt Stress Tolerance in Transgenic Arabidopsis.

Soil salinization is a major abiotic stress factor that negatively impacts plant growth, development, and crop yield, severely limiting agricultural production and economic development. Cotton, a key cash crop, is commonly cultivated as a pioneer crop in regions with saline-alkali soil due to its relatively strong tolerance to salt. This characteristic renders it a valuable subject for investigating the molecular mechanisms underlying plant salt tolerance and for identifying genes that confer salt tolerance. In this study, focus was placed on examining a salt-tolerant variety, E991, and a salt-sensitive variety, ZM24. A combined analysis of transcriptomic data from these cotton varieties led to the identification of potential salt stress-responsive genes within the glutathione S-transferase (GST) family. These versatile enzyme proteins, prevalent in animals, plants, and microorganisms, were demonstrated to be involved in various abiotic stress responses. Our findings indicate that suppressing GhGSTF9 in cotton led to a notably salt-sensitive phenotype, whereas heterologous overexpression in Arabidopsis plants decreases the accumulation of reactive oxygen species under salt stress, thereby enhancing salt stress tolerance. This suggests that GhGSTF9 serves as a positive regulator in cotton's response to salt stress. These results offer new target genes for developing salt-tolerant cotton varieties.

Unravelling the halophyte Suaeda maritima as an efficient candidate for phytostabilization of cadmium and lead: Implications from physiological, ionomic, and metabolomic responses.

Cadmium (Cd) and lead (Pb) are among the most toxic heavy metals affecting human health and crop yield. Suaeda maritima (L.) Dumort is an obligate halophyte that is well adapted to saline soil. The inbuilt salinity tolerance mechanisms of halophytes help them to survive in heavy metal-contaminated rhizospheric soil. In the present study, growth and ionomic responses, reactive oxygen species (ROS) accumulation, modulations of phytochelatins, antioxidative defense, and metabolomic responses were studied in S. maritima imposed to Cd and Pb stresses with an aim to elucidate Cd and Pb tolerance mechanisms and phytoremediation potential of this halophyte. Our results showed a reduction of biomass in S. maritima, which may serve as an energy conservation strategy for survival under heavy metal stress. The increased accumulation of ROS with concomitant higher expression of various antioxidative enzymes suggests the efficient scavenging of ROS. The metabolite profiling revealed significant up-regulation of sugars, sugar alcohols, amino acids, polyphenols, and organic acids under Cd and Pb stresses suggesting their possible role in osmotic balance, ionic homeostasis, ROS scavenging, and signal transduction for stress tolerance. In S. maritima, the translocation factors (Tf) are <1 in both Cd and Pb treatments, which indicates that this halophyte has high phytostabilization potential for Cd and Pb in roots and through restricted translocation of heavy metal ions to the aboveground part. The findings of this study offer comprehensive information on Cd and Pb tolerance mechanisms in S. maritima and suggest that this halophyte can detoxify the HMs through physiological, ionic, antioxidative, and metabolic regulations.

Effect of salt-alkali stress on seed germination of the halophyte Halostachys caspica.

The increasing global phenomenon of soil salinization has prompted heightened interest in the physiological ecology of plant salt and alkali tolerance. Halostachys caspica belonging to Amaranthaceae, an exceptionally salt-tolerant halophyte, is widely distributed in the arid and saline-alkali regions of Xinjiang, in Northwest China. Soil salinization and alkalinization frequently co-occur in nature, but very few studies focus on the interactive effects of various salt and alkali stress on plants. In this study, the impacts on the H. caspica seed germination, germination recovery and seedling growth were investigated under the salt and alkali stress. The results showed that the seed germination percentage was not significantly reduced at low salinity at pH 5.30-9.60, but decreased with elevated salt concentration and pH. Immediately after, salt was removed, ungerminated seeds under high salt concentration treatment exhibited a higher recovery germination percentage, indicating seed germination of H. caspica was inhibited under the condition of high salt-alkali stress. Stepwise regression analysis indicated that, at the same salt concentrations, alkaline salts exerted a more severe inhibition on seed germination, compared to neutral salts. The detrimental effects of salinity or high pH alone were less serious than their combination. Salt concentration, pH value, and their interactions had inhibitory effects on seed germination, with salinity being the decisive factor, while pH played a secondary role in salt-alkali mixed stress.

The WRKY gene family in the halophyte Limonium bicolor: identification, expression analysis, and regulation of salt stress tolerance.

KEY MESSAGE: 63 L. bicolor WRKY genes were identified and their informatics was analyzed. The results suggested that the LbWRKY genes involved in the development and salt secretion of salt glands in L. bicolor. Salt stress, as a universal abiotic stress, severely inhibits the growth and development of plants. WRKY transcription factors play a vital role in plant growth and development, as well as in response to various stresses. Nevertheless, little is known of systematic genome-wide analysis of the WRKY genes in Limonium bicolor, a model recretohalophyte. In this study, 63 L. bicolor WRKY genes were identified (LbWRKY1-63), which were unevenly distributed across seven chromosomes and one scaffold. Based on the structural and phylogenetic characteristics, 63 LbWRKYs are divided into three main groups. Cis-elements in the LbWRKY promoters were related to growth and development, phytohormone responses, and stress responses. Colinearity analysis showed strong colinearity between LbWRKYs and GmWRKYs from soybean (Glycine max). Therefore, LbWRKY genes maybe have similar functions to GmWRKY genes. Expression analysis showed that 28 LbWRKY genes are highly expressed in roots, 9 in stems, 26 in leaves, and 12 in flowers and most LbWRKY genes responded to NaCl, ABA, and PEG6000. Silencing LbWRKY10 reduced salt gland density and salt secretion ability of leaves, and the salt tolerance of the species. Consistent with this, genes associated with salt gland development were markedly down-regulated in the LbWRKY10-silenced lines. Our findings suggested that the LbWRKY genes involved in the development and salt secretion of salt glands in L. bicolor. Our research provides new insights into the functions of the WRKY family in halophytes.

HgS2, a novel salt-responsive gene from the Halophyte Halogeton glomeratus, confers salt tolerance in transgenic Arabidopsis.

Halophyte Halogeton glomeratus mostly grows in saline desert areas in arid and semi-arid regions and is able to adapt to adverse conditions such as salinity and drought. Earlier transcriptomic studies revealed activation of the HgS2 gene in the leaf of H. glomeratus seedlings when exposed to saline conditions. To identify the properties of HgS2 in H. glomeratus, we used yeast transformation and overexpression in Arabidopsis. Yeast cells genetically transformed with HgS2 exhibited K+ uptake and Na+ efflux compared with control (empty vector). Stable overexpression of HgS2 in Arabidopsis improved its resistance to salt stress and led to a notable rise in seed germination in salinity conditions compared to the wild type (WT). Transgenic Arabidopsis regulated ion homeostasis in plant cells by increasing Na+ absorption and decreasing K+ efflux in leaves, while reducing Na+ absorption and K+ efflux in roots. In addition, overexpression of HgS2 altered transcription levels of stress response genes and regulated different metabolic pathways in roots and leaves of Arabidopsis. These results offer new insights into the role of HgS2 in plants' salt tolerance.

Klenkia sesuvii sp. nov., isolated from leaves of halophyte Sesuvium portulacastrum.

During a study on the diversity of culturable actinobacteria from coastal halophytes in Thailand, strain LSe6-5T was isolated from leaves of sea purslane (Sesuvium portulacastrum L.), and a polyphasic approach was employed to determine its taxonomic position. The 16S rRNA gene sequences analysis indicated that the strain was most closely related to Klenkia brasiliensis Tu 6233T (99.2 %), Klenkia marina YIM M13156T (99.1 %), and Klenkia terrae PB261T (98.7 %). The genome of strain LSe6-5T was estimated to be 4.33 Mbp in size, with DNA G+C contents of 74.3%. A phylogenomic tree based on whole-genome sequences revealed that strain LSe6-5T formed a clade with Klenkia marina DSM 45722T, indicating their close relationship. However, the average nucleotide identity (ANI)-blast, ANI-MUMmer, and dDDH values between strain LSe6-5T with K. marina DSM 45722T (87.1, 88.9, and 33.0 %) were below the thresholds of 95-96 % ANI and 70 % dDDH for identifying a novel species. Furthermore, strain LSe6-5T showed morphological and chemotaxonomic characteristics of the genus Klenkia. Cells were motile, rod-shaped, and Gram-stain-positive. Optimal growth of strain LSe6-5T occurred at 28 °C, pH 7.0, and 0-3 % NaCl. The whole-cell hydrolysates contained meso-diaminopimelic acid as the diagnostic diamino acid, with galactose, glucose, mannose, and ribose as whole-cell sugars. The predominant menaquinones were MK-9(H4) and MK-9(H0). The polar lipid profile was composed of diphosphatidylglycerol, hydroxyphosphatidylethanolamine, phosphatidylinositol, glycophosphatidylinositol, an unidentified phospholipid, and an unidentified lipid. Major cellular fatty acids were iso-C15 : 0, iso-C16 : 0, and iso-C17 : 0. From the distinct phylogenetic position and combination of genotypic and phenotypic characteristics, it is supported that strain LSe6-5T represents a novel species of the genus Klenkia, for which the name Klenkia sesuvii sp. nov. is proposed. The type strain is strain LSe6-5T (=TBRC 16417T= NBRC 115929T).

Alternative electron sinks in chloroplasts and mitochondria of halophytes as a safety valve for controlling ROS production during salinity.

Electron flow through the electron transport chain (ETC) is essential for oxidative phosphorylation in mitochondria and photosynthesis in chloroplasts. Electron fluxes depend on environmental parameters, e.g., ionic and osmotic conditions and endogenous factors, and this may cause severe imbalances. Plants have evolved alternative sinks to balance the reductive load on the electron transport chains in order to avoid overreduction, generation of reactive oxygen species (ROS), and to cope with environmental stresses. These sinks act primarily as valves for electron drainage and secondarily as regulators of tolerance-related metabolism, utilizing the excess reductive energy. High salinity is an environmental stressor that stimulates the generation of ROS and oxidative stress, which affects growth and development by disrupting the redox homeostasis of plants. While glycophytic plants are sensitive to high salinity, halophytic plants tolerate, grow, and reproduce at high salinity. Various studies have examined the ETC systems of glycophytic plants, however, information about the state and regulation of ETCs in halophytes under non-saline and saline conditions is scarce. This review focuses on alternative electron sinks in chloroplasts and mitochondria of halophytic plants. In cases where information on halophytes is lacking, we examined the available knowledge on the relationship between alternative sinks and gradual salinity resilience of glycophytes. To this end, transcriptional responses of involved components of photosynthetic and respiratory ETCs were compared between the glycophyte Arabidopsis thaliana and the halophyte Schrenkiella parvula, and the time-courses of these transcripts were examined in A. thaliana. The observed regulatory patterns are discussed in the context of reactive molecular species formation in halophytes and glycophytes.

Extraction of cellulose from halophytic plants for the synthesis of a novel biocomposite.

Cellulose nanofibers, a sustainable and promising material with widespread applications, exhibit appreciable strength and excellent mechanical and physicochemical properties. The preparation of cellulosic nanofibers from food or agricultural residue is not sustainable. Therefore, this study was designed to use three halophytic plants (Cressa cretica, Phragmites karka, and Suaeda fruticosa) to extract cellulose for the subsequent conversion to cellulosic nanofibers composites. The other extracted biomass components including lignin, hemicellulose, and pectin were also utilized to obtain industrially valuable enzymes. The maximum pectinase (31.56 IU mL-1), xylanase (35.21 IU mL-1), and laccase (15.89 IU mL-1) were produced after the fermentation of extracted pectin, hemicellulose, and lignin from S. fruticosa, P. karka, and C. cretica, respectively. Cellulose was methylated (with a degree of substitution of 2.4) and subsequently converted into a composite using polyvinyl alcohol. Scanning electron microscopy and Fourier-transform infrared spectroscopy confirmed the successful synthesis of the composites. The composites made up of cellulose from C. cretica and S. fruticosa had a high tensile strength (21.5 and 15.2 MPa) and low biodegradability (47.58% and 44.56%, respectively) after dumping for 3 months in soil, as compared with the composite from P. karka (98.79% biodegradability and 4.9 MPa tensile strength). Moreover, all the composites exhibited antibacterial activity against gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae) and gram-positive bacteria (Staphylococcus aureus). Hence, this study emphasizes the possibility for various industrial applications of biomass from halophytic plants.

How the Ethylene Biosynthesis Pathway of Semi-Halophytes Is Modified with Prolonged Salinity Stress Occurrence?

The mechanism of ethylene (ET)-regulated salinity stress response remains largely unexplained, especially for semi-halophytes and halophytes. Here, we present the results of the multifaceted analysis of the model semi-halophyte Mesembryanthemum crystallinum L. (common ice plant) ET biosynthesis pathway key components' response to prolonged (14 days) salinity stress. Transcriptomic analysis revealed that the expression of 3280 ice plant genes was altered during 14-day long salinity (0.4 M NaCl) stress. A thorough analysis of differentially expressed genes (DEGs) showed that the expression of genes involved in ET biosynthesis and perception (ET receptors), the abscisic acid (ABA) catabolic process, and photosynthetic apparatus was significantly modified with prolonged stressor presence. To some point this result was supported with the expression analysis of the transcript amount (qPCR) of key ET biosynthesis pathway genes, namely ACS6 (1-aminocyclopropane-1-carboxylate synthase) and ACO1 (1-aminocyclopropane-1-carboxylate oxidase) orthologs. However, the pronounced circadian rhythm observed in the expression of both genes in unaffected (control) plants was distorted and an evident downregulation of both orthologs' was induced with prolonged salinity stress. The UPLC-MS analysis of the ET biosynthesis pathway rate-limiting semi-product, namely of 1-aminocyclopropane-1-carboxylic acid (ACC) content, confirmed the results assessed with molecular tools. The circadian rhythm of the ACC production of NaCl-treated semi-halophytes remained largely unaffected by the prolonged salinity stress episode. We speculate that the obtained results represent an image of the steady state established over the past 14 days, while during the first hours of the salinity stress response, the view could be completely different.

Role of the salt glands of Armeria maritima (halophyte) in removal of lead from tissues.

Armeria maritima is a halophyte exhibiting a strong tolerance to heavy metals. It grows on zinc-lead waste heaps. This study aimed to determine the role of salt glands in the removal of lead (Pb) from plants and to trace the path of lead from the shoots to the salt glands on the surface of leaves. Mechanisms allowing high tolerance to lead in A. maritima were also evaluated. These examinations were conducted on a lead-tolerant population and a lead-sensitive plant population. The plants were treated with Pb(NO3)2 and the path of lead was traced from the roots to the leaves. The lead-tolerant population transported twice as much lead as the sensitive population. The action of the salt glands resulted in 40% of the leaf lead content in the lead-tolerant population being expelled onto the surface of the leaves. These features indicate the high phytoremediation capabilities of these halophyte plants. The excretion of multi-ionic solutes by the salt glands results in the appearance of tiny crystals on the surface of the leaves. In this publication, for the first time, an attempt was made to determine what chemical compounds build up these crystals and to determine their crystal structure. Solving this problem was possible through the usage of single-crystal X-ray structural analysis.

Molecular cloning and characterization of a salt overly sensitive3 (SOS3) gene from the halophyte Pongamia.

A high concentration of sodium (Na+) is the primary stressor for plants in high salinity environments. The Salt Overly Sensitive (SOS) pathway is one of the best-studied signal transduction pathways, which confers plants the ability to export too much Na+ out of the cells or translocate the cytoplasmic Na+ into the vacuole. In this study, the Salt Overly Sensitive3 (MpSOS3) gene from Pongamia (Millettia pinnata Syn. Pongamia pinnata), a semi-mangrove, was isolated and characterized. The MpSOS3 protein has canonical EF-hand motifs conserved in other calcium-binding proteins and an N-myristoylation signature sequence. The MpSOS3 gene was significantly induced by salt stress, especially in Pongamia roots. Expression of the wild-type MpSOS3 but not the mutated nonmyristoylated MpSOS3-G2A could rescue the salt-hypersensitive phenotype of the Arabidopsis sos3-1 mutant, which suggested the N-myristoylation signature sequence of MpSOS3 was required for MpSOS3 function in plant salt tolerance. Heterologous expression of MpSOS3 in Arabidopsis accumulated less H2O2, superoxide anion radical (O2-), and malondialdehyde (MDA) than wild-type plants, which enhanced the salt tolerance of transgenic Arabidopsis plants. Under salt stress, MpSOS3 transgenic plants accumulated a lower content of Na+ and a higher content of K+ than wild-type plants, which maintained a better K+/Na+ ratio in transgenic plants. Moreover, no development and growth discrepancies were observed in the MpSOS3 heterologous overexpression plants compared to wild-type plants. Our results demonstrated that the MpSOS3 pathway confers a conservative salt-tolerant role and provided a foundation for further study of the SOS pathway in Pongamia.

Marine sediments in the Gulf of Gabes (Tunisia) heavily polluted by phosphogypsum and human microbiota bacteria: phytoremediation by Salicornia europaea as a natural-based solution.

A huge amount of phosphogypsum (PG) wastes generated from the processing phosphate ore in Tunisia Industrial Group Area-Gabes is getting discarded into the sea. Within this framework, the basic objective of this research is to elaborate and discuss a natural-based solution focused on phytoremediation of contaminated (PG) soils and marine sediments with the halophilic plant Salicornia europaea. A significant drop of the organic matter (53.09%), moisture (26.47%), and sediment porosity with (5.88%) was detected in the rhizosphere Salicornia europaea area (RS). Removal of hazardous elements concentrations, such as Pb, Fe, Cu, Cd, and Zn, between contaminated sediment (CS) and RS displayed a significant difference, ranging from 5.33 to 50.02% of hazardous elements removal concentration, which was observed in the rhizosphere zone. The microbiota of both areas (RS and CS) were analyzed by massive sequencing. In both samples, all the sequences belong to only four phyla: Firmicutes and, to a much lower extent, Proteobacteria, Bacteroidetes, and Actinobacteria. The CS sediment seems to be heavily polluted by human activities. Most of the found genera are inhabitants of the intestine of warm-blooded animals (Escherichia, Bacteroides, Prevotella, Faecalibacterium, Ruminococcus, Enterococcus); hence, activities in this area pose a health risk. On the other hand, it may be surprising that 76.4% of the total high-quality sequences retrieved from the RS sample were affiliated to the family Bacillaceae. The salinity of the studied soil exerts a stress on the microbial populations that inhabit it, directing the selection of halotolerant species.

Structural characterization and potential anti-tumor activity of a polysaccharide from the halophyte Salicornia bigelovii Torr.

Plant polysaccharides are highly potent bioactive molecules. Clarifying the structural composition and bioactivities of plant polysaccharides will provide insights into their structure-activity relationships. Therefore, herein, we identified a polysaccharide produced by Salicornia bigelovii Torr. and analyzed the structure and anti-tumor activity of its component, SabPS-1. SabPS-1 was 3.24 × 104 Da, primarily composed of arabinose (24.96 %), galactose (30.39 %), and galacturonic acid (23.20 %), rhamnose (6.21 %), xylose (4.99 %), glucuronic acid (3.12 %), mannuronic acid (1.75 %), mannose (1.69 %), glucose (1.54 %), fucose (1.12 %), and guluronic acid (1.03 %). The backbone of SabPS-1 was a â†’ 4)-ß-D-GalpA-(1→, →5)-α-L-Araf-(1→, and→4)-ß-D-Galp-(1 â†’ molecule with a branched chain of α-L-Araf-(1 â†’ connected to sugar residues of →3,6)-ß-D-Galp-(1 â†’ in the O-3 position. SabPS-1 induced apoptosis and inhibited the growth of HepG-2 cells, with viability of 47.90 ± 4.14 (400 µg/mL), indicating anti-tumor activity. Apoptosis induced by SabPS-1 may be associated with the differential regulation of caspase 3, caspase 8, Bax, and Bcl-2. To the best of our knowledge, this is the first study to investigate the principal structures and anti-tumor biological activities of SabPS-1. Our findings demonstrated the excellent anti-tumor properties of SabPS-1, which will aid in the development of anti-tumor drugs utilizing Salicornia bigelovii Torr.

Gordonia prachuapensis sp. nov. and Gordonia sesuvii sp. nov., two novel actinobacteria isolated from mangrove sediments and leaves of halophyte Sesuvium portulacastrum in Thailand.

A polyphasic approach was used to characterize two novel actinobacterial strains, designated PKS22-38T and LSe1-13T, which were isolated from mangrove soils and leaves of halophyte Sesuvium portulacastrum (L.), respectively. Phylogenetic analyses based on 16S rRNA gene sequences showed that they belonged to the genus Gordonia and were most closely related to three validly published species with similarities ranging from 98.6 to 98.1 %. The genomic DNA G+C contents of strains PKS22-38T and LSe1-13T were 67.3 and 67.2 mol%, respectively. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between the two strains were 93.3 and 54.9 %, respectively, revealing that they are independent species. Meanwhile, the ANI and dDDH values between the two novel strains and closely related type strains were below 80.5 and 24.0 %, respectively. Strains PKS22-38T and LSe1-13T contained C16 : 0, C18 : 1 ω9c and C18 : 0 10-methyl (TBSA) as the major fatty acids and diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylinositol as the main phospholipids. The predominant menaquinone was MK-9(H2). Based on phenotypic, chemotaxonomic, phylogenetic and genomic data, strains PKS22-38T and LSe1-13T are considered to represent two novel species within the genus Gordonia, for which the names Gordonia prachuapensis sp. nov. and Gordonia sesuvii sp. nov. are proposed, with strain PKS22-38T (=TBRC 17540T=NBRC 116256T) and strain LSe1-13T (=TBRC 17706T=NBRC 116396T) as the type strains, respectively.

From swamp to field: how genes from mangroves and its associates can enhance crop salinity tolerance.

Salinity stress is a critical challenge in crop production and requires innovative strategies to enhance the salt tolerance of plants. Insights from mangrove species, which are renowned for their adaptability to high-salinity environments, provides valuable genetic targets and resources for improving crops. A significant hurdle in salinity stress is the excessive uptake of sodium ions (Na+) by plant roots, causing disruptions in cellular balance, nutrient deficiencies, and hampered growth. Specific ion transporters and channels play crucial roles in maintaining a low Na+/K+ ratio in root cells which is pivotal for salt tolerance. The family of high-affinity potassium transporters, recently characterized in Avicennia officinalis, contributes to K+ homeostasis in transgenic Arabidopsis plants even under high-salt conditions. The salt overly sensitive pathway and genes related to vacuolar-type H+-ATPases hold promise for expelling cytosolic Na+ and sequestering Na+ in transgenic plants, respectively. Aquaporins contribute to mangroves' adaptation to saline environments by regulating water uptake, transpiration, and osmotic balance. Antioxidant enzymes mitigate oxidative damage, whereas genes regulating osmolytes, such as glycine betaine and proline, provide osmoprotection. Mangroves exhibit increased expression of stress-responsive transcription factors such as MYB, NAC, and CBFs under high salinity. Moreover, genes involved in various metabolic pathways, including jasmonate synthesis, triterpenoid production, and protein stability under salt stress, have been identified. This review highlights the potential of mangrove genes to enhance salt tolerance of crops. Further research is imperative to fully comprehend and apply these genes to crop breeding to improve salinity resilience.