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Rice straw breakdown is sluggish, which makes agricultural waste management difficult, however pretreatment procedures and cellulolytic fungi can address this issue. Through ITS sequencing, Chaetomium globosum C1, Aspergillus sp. F2, and Ascomycota sp. SM2 were identified from diverse sources. Ascomycota sp. SM2 exhibited the highest carboxymethyl cellulase (CMCase) activity (0.86 IU/mL) and filter-paper cellulase (FPase) activity (1.054 FPU/mL), while Aspergillus sp. F2 showed the highest CMCase activity (0.185 IU/mL) after various pretreatments of rice straw. These fungi thrived across a wide pH range, with Ascomycota sp. SM2 from pH 4 to 9, Aspergillus sp. F2, and Chaetomium globosum C1 thriving in alkaline conditions (pH 9). FTIR spectroscopy revealed significant structural changes in rice straw after enzymatic hydrolysis and solid-state fermentation, indicating lignin, cellulose, and hemicellulose degradation. Soil amendments with pretreated rice straw, cow manure, biochar, and these fungi increased root growth and soil nutrient availability, even under severe salt stress (up to 9.3 dS/m). The study emphasizes the need for a better understanding of Ascomycota sp. degradation capabilities and proposes that using cellulolytic fungus and pretreatment rice straw into soil amendments could mitigate salt-related difficulties and improve nutrient availability in salty soils. [ABSTRACT FROM AUTHOR]

Ethylene promotes seed germination under stress, but the optimum concentration and effect on cotton seeds under salt stress are unclear. In this paper, Nongdamian 601 seeds were used to identify the optimal ethephon (ethylene donor) concentration that promotes cotton seed germination, using 2–150-mM NaCl stress as the study range. The study also examined the effect and physiological characteristics at the optimal ethephon concentration to alleviate cotton seed germination under salt stress. At 150-mM NaCl stress, 2-mM ethephon treatment significantly increased the germination rate and germination potential of cotton seeds by 73.30 and 66.00%. At 7 days of germination, ethephon treatment reduced root length, surface area, and volume more than salt stress, but ethephon increased root diameter. Moreover, ethephon treatment significantly increased the contents of superoxide dismutase, peroxidase, proline, and soluble sugar of seeds than salt stress. Ethephon significantly increased the content of malondialdehyde. These results indicate that ethylene enhances the salt tolerance and germination rate of cotton seeds by enhancing the activity of antioxidant enzymes, increasing proline content, and alleviating the degree of membrane lipid peroxidation. [ABSTRACT FROM AUTHOR]

Multidrug and Toxic Compound Extrusion (MATE) proteins are essential transporters that extrude metabolites and participate in plant development and cellular detoxification. MATE transporters, which play crucial roles in the survival of mangrove plants under highly challenged environments, by specialized salt extrusion mechanisms, are mined from their genomes and reported here for the first time. Through homology search and domain prediction in the genome assemblies of Avicennia marina, Bruguiera sexangula, Ceriops zippeliana, Kandelia obovata, Rhizophora apiculata and Ceriops tagal, 74, 68, 66, 66, 63 and 64 MATE proteins, respectively were identified. The phylogenetic analysis divided the identified proteins into five major clusters and following the clustering pattern of the functionally characterized proteins, functions of the transporters in each cluster were predicted. Amino acid sequences, exon-intron structure, motif details and subcellular localization pattern for all the 401 proteins are described. The custom designed repeat masking libraries generated for each of these genomes, which will be of extensive use for the researchers worldwide, are also provided in this paper. This is the first study on the MATE genes in mangroves and the results provide comprehensive information on the molecular mechanisms enabling the survival of mangroves under hostile conditions. [ABSTRACT FROM AUTHOR]

PHLOEM PROTEIN 2-A1 like (PP2-A1) gene is a member of the PP2 multigene family, and the protein encoded by which has the function of stress defense. Based on our previous proteomic study of cucumber phloem sap, CsPP2-A1 protein expression was significantly enriched under salt stress. In this paper, we obtained CsPP2-A1 interfering (CsPP2-A1-RNAi) cucumber by Agrobacterium tumefaciens-mediated method. The phenotypic changes of wild-type (WT) cucumber, CsPP2-A1-overexpressing (OE) cucumber, and CsPP2-A1-RNAi cucumber under salt treatment were observed and compared. Furthermore, physiological indicators were measured in four aspects: osmoregulation, membrane permeability, antioxidant system, and photosynthetic system. The analysis of contribution and correlation for each variable were conducted by principal component analysis (PCA) and Pearson's correlation coefficient. The above results showed that CsPP2-A1-RNAi cucumber plants exhibited weaker salt tolerance compared to WT cucumber and CsPP2-A1-OE cucumber plants in terms of phenotype and physiological indicators in response to salt stress, while CsPP2-A1-OE cucumber always showed the robust salt tolerance. Together, these results indicated that CsPP2-A1 brought a salinity tolerance ability to cucumber through osmoregulation and reactive oxygen species (ROS) homeostasis. The results of the study provided evidence for the function of CsPP2-A1 in plant salt tolerance enhancement, and they will serve as a reference for future salt-tolerant cucumber genetic manipulation. [ABSTRACT FROM AUTHOR]

The secondary salinization of soil in facility agriculture is becoming increasingly serious. Cucumber is a moderately salt-sensitive crop, but because of the weak root system and poor resistance to salt stress in cucumber seedlings, it is sensitive to the accumulation of salt in facility soils. Hydrogen, a selective antioxidant and signal molecule, is nontoxic and harmless, and can repair damage in plants under stress. Therefore, the aim of the present paper was to understand the specific mechanism by which hydrogen-rich water (HRW) alleviated salt stress in cucumber seedlings (Cucumis sativus L.). Our results showed that the addition of 50% saturation HRW significantly promoted seedling growth, development and photosynthetic efficiency. Pretreatment with HRW significantly alleviated salt stress symptoms, including the inhibition of fresh and dry weight, root length, lateral roots, and the root/shoot ratio of cucumber seedlings. Pretreatment with HRW increased the chlorophyll content, chlorophyll a/b ratio, and photochemical reaction efficiency, and reduced energy dissipation. These responses to HRW pretreatment were consistent with significant decreases in the superoxide anion, hydrogen peroxide, and malondialdehyde contents and the degree of lipid peroxidation, and increases in the activities of SOD, POD, CAT, APX and GR, and the contents of ASA and GSH in cucumber seedlings under salt stress. In addition, HRW pretreatment under salt stress inhibited the expression of the protein kinase ROP1, which promoted the production of reactive oxygen, but upregulated the protein kinase LecRLK. The transcription factor TGA5, which was involved in osmotic stress, ion stress and ROS clearance, and the expression of NHX1 and SOS2, which were parts of the SOS signaling pathway. HRW enhanced the expression of genes that encoded antioxidant enzymes, including SOD, CAT and POD, and the expressions of GR and APX2, which were key genes in the ASA-GSH cycle under salt stress. Taken together, these results suggested that HRW enhanced the active oxygen scavenging ability in cucumber seedlings, promoted the redox balance in cells, and reduced the degree of oxidative damage in plants under salt stress by reducing the content of active oxygen. Therefore, the application of HRW might be a promising strategy for improving salt stress tolerance in cucumber seedlings. [ABSTRACT FROM AUTHOR]

In recent years, plant growth-promoting rhizobacteria (PGPR) have received increased attention due to their prospective use as biofertilizers for the enhancement of crop growth and yields. However, there is a growing need to identify new PGPR isolates with additional beneficial properties. In this paper, we describe the identification of a new strain of a non-sporulating Gram-positive bacterium isolated from the rhizosphere of potato plants, classified as Brevibacterium sediminis MG-1 based on whole-genome sequencing. The bacteria are aerobic; they grow in a pH range of 6.0–10.0 (optimum 6.0), and a temperature range of 20–37 °C (optimum 30 °C). At 96 h of cultivation, strain MG-1 synthesizes 28.65 µg/ml of indole-3-acetic acid (IAA) when 500 µg/ml of l-tryptophan is added. It is a producer of catechol-type siderophores and ACC deaminase (213 ± 12.34 ng/ml) and shows halotolerance. Treatment of pea, rye, and wheat seeds with a suspension of MG-1 strain cells resulted in the stimulation of stem and root biomass accumulation by 12–26% and 6–25% (P < 0.05), respectively. Treatment of seeds with bacteria in the presence of high salt concentration reduced the negative effects of salt stress on plant growth by 18–50%. The hypothetical gene lin, encoding the bacteriocin Linocin-M18, RIPP-like proteins, and polyketide synthase type III (T3PKS) loci, gene clusters responsible for iron acquisition and metabolism of siderophores, as well as gene clusters responsible for auxin biosynthesis, were identified in the B. sediminis MG-1 genome. Thus, the rhizosphere-associated strain B. sediminis MG-1 has growth-stimulating properties and can be useful for the treatment of plants grown on soils with high salinity. [ABSTRACT FROM AUTHOR]

Background: Cold shock proteins (CSPs) are ubiquitous nucleic acid-binding proteins involved in growth, development, and stress response across various organisms. While extensively studied in many species, their regulatory roles in sweet cherry (Prunus avium L.) remain unclear. Objective: To identify and analyze CSP genes (PavCSPs) in sweet cherry genome, and explore the differential responses of PavCSP1 and PavCSP3 to low temperature and salt stress. Methods: Three methods were employed to identify and characterize CSP in sweet cherry genomes. To explore the potential functions and evolutionary relationships of sweet cherry CSP proteins, sequence alignment and phylogenetic tree incorporating genes from five species were conducted and constructed, respectively. To investigate the responses to abiotic stresses, cis-acting elements analysis and gene expression patterns to low-temperature and salt stress were examined. Moreover, transgenic yeasts overexpressing PavCSP1 or PavCSP3 were generated and their growth under stress conditions were observed. Results: In this study, three CSP genes (PavCSPs) were identified and comprehensively analyzed. The quantitative real-time PCR revealed diverse expression patterns, with PavCSP1-3 demonstrating a particular activity in the upper stem and all members were responsive to low-temperature and salt stress. Further investigation demonstrated that transgenic yeasts overexpressing PavCSP1 or PavCSP3 exhibited improved growth states following high-salt and low-temperature stress. Conclusion: These findings elucidated the responses of PavCSP1 and PavCSP3 to salt and low-temperature stresses, laying the groundwork for further functional studies of PavCSPs in response to abiotic stresses. [ABSTRACT FROM AUTHOR]

Matricaria chamomilla (Asteraceae), commonly known as chamomile can tolerate freezing temperatures and grows in many soil types. This plant is found on all continents and has significant medicinal value. There are more than 120 chemicals detected in chamomile flowers, with the majority found in the essential oil. In this study, M. chamomilla was given the NaCl stress of 0 mM, 1 mM, 100 mM, and 150 mM concentrations This study was the first to assess the efficacy of German chamomile upon exposure to salt stress hence plant particles that had been dried and powdered were analyzed using, phytochemical tests, Fourier Transform Infrared and UV–Vis spectroscopy, thin layer chromatography, fluorescence recovery after photobleaching assay, antibacterial and antioxidant activity. The characterization and results of these activities show amazing results which enhance their antibacterial property with an increased zone of inhibition when the samples of salt stress of the above-given concentrations were compared to the control samples. More graph analysis indicates an effective impact of salt stress on the phytoconstituents of M. chamomilla. Other than that, there was a clear flower induction upon salt stress, as a variety of compounds are regarded as essential to the biological functions of chamomile flowers according to the phytoconstituent screening which can be further used in the cosmetic industry, pharmaceutical industry, and all other fields as well for various application as a nano-drug or bio-drug. Due to this, this plant became essential for plant biotechnology research. [ABSTRACT FROM AUTHOR]

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a key enzyme in the glycolytic pathway. GAPDHs contribute to many non-glycolytic processes such as transcriptional regulation, DNA repair, signal transduction cascades, autophagy, and apoptosis in mammalian cells. In plants, GAPDH has been implicated in the response to salt stress, but precisely how its functions in this regard remains unclear. In the present study, we identified an GAPDH gene from the Chenopodiaceae euhalophyte Halostachys caspica (HcGAPDH) as a senescence component of the plant salt stress response. Enhanced expression of HcGAPDH was observed under salt stress and abscisic acid treatment. Green fluorescent protein-tagged HcGAPDH localized to the cytosol of transgenic Arabidopsis thaliana cells, and salt stress induced the translocation of HcGAPDH protein into the nucleus, which was different from carbohydrate-mediated feedback signaling. Ectopic expression of HcGAPDH resulted in retarded growth of Arabidopsis plants and suppressed chlorophyll production, and darkness accelerated chlorotic leaf senescence in HcGAPDH-overexpressing lines. Moreover, the transcript levels of senescence-associated genes were markedly increased in transgenic plants compared to WT and atgapdh mutants. Taken together, the data indicate that under salt stress conditions, HcGAPDH translocates from the cytosol to the nucleus and functions in senescence regulation. [ABSTRACT FROM AUTHOR]

To study the effect of brassinosteroids and salinity stress on the fatty acid metabolism in the seeds of oil plants, the authors analyzed the turnover of fatty acids in the seeds of Crambe tatarica under the mentioned conditions. The results of gas-liquid chromatography and mass-spectrometry demonstrated the decrease in the level of palmitic and linoleic fatty acids along with the increase in the level of oleic, eicosenoic, and docosenoic fatty acids in C. tatarica seeds in response to 28-homobrassinolide under salinity stress on some stages of seed germination. These regularities allowed for the assumption that 28-homobrassinolide promotes the stabilization of fatty acid composition of C. tatarica seeds, disrupted under salinity stress. This may indicate the possibility of modulating the activity or expression of desaturase genes and the enzymes of fatty acid oxidation in the anwer on brassinosteroids. [ABSTRACT FROM AUTHOR]

Acetylcholine (ACh), a potential plant growth regulator, can alleviate injury caused by NaCl and cadmium stress. However, the underlying mechanisms whereby it affects seed germination remain unclear. We pre-soaked maize (Zea mays L.) in different concentrations (1–3 μm) of ACh. Seed germination and levels of β-galactosidase, α-amylase, and starch were analyzed. ACh, abscisic acid (ABA), and gibberellic acid levels were estimated via enzyme-linked immunosorbent assay. The expression of ABA and gibberellic acid signaling-related genes was analyzed. Salt stress significantly reduced seed germination and hypocotyl elongation but increased ABA and H2O2 levels and enhanced antioxidant enzyme activity. Priming with 2 μm ACh caused a significantly higher germination rate (by 13.4%) relative to that of the seeds subjected to salt stress alone. Under salt stress, ACh effectively upregulated α-amylase and β-galactosidase activity (by 0.63- and 1.04-fold) and reduced starch content (by 34.02%). ACh treatment downregulated the expression of ZmNCED3 (involved in ABA signaling) and upregulated that of ZmKAO (involved in gibberellin signaling). The leaves of the seedlings pretreated with ACh presented higher antioxidant enzyme activity and, therefore, lower H2O2 accumulation than those of seedlings subjected to salt stress alone. Priming the maize seeds with exogenous ACh maintained seedling growth under salt stress. ACh pretreatment increased antioxidant activity, reduced ABA activity, and improved salt tolerance in maize seeds exposed to salt stress. These findings suggest that pretreatment with 2 μm ACh improves seed germination, activates ROS scavenging, and regulates phytohormone levels under salt stress, thereby improving growth. [ABSTRACT FROM AUTHOR]

Quantifying the level of seed germiabiliy of herbicide-resistant (R) and susceptible (S) weeds is useful for understanding the evolutionary development of herbicide resistance, but also for implementing herbicide-resistance management strategies. Germination is a crucial aspect in the life phase of weeds. Phalaris brachystachys biotypes resistant to ACCase-inhibiting herbicides have been confirmed in wheat fields in Iran. This study aimed to investigate the germination behaviour of ACCase- resistant and susceptible subpopulations P. brachystachys under different environmental factors. An analysis of the seed germination of P. brachystachys sub populations at the seed stage was therefore conducted. The resistant (R) and susceptible (S) P. brachystachys subpopulation germination traits were tested in different temperature, salinity stress, drought, and burial depth conditions. All tests were carried out with five replications in a completely randomized design. The highest germination percentage in both subpopulations occurred at a temperature range of 20 to 25 °C. At 35 °C, no germination occurred. In terms of estimated cardinal temperatures, no differences were observed between S and R subpopulations. Seeds containing the ACCase Ile-1781-Thr mutation germinated better under salt and osmotic stress. There were no fitness differences in pH conditions. The percentage and rate of emergence of the R subpopulation were more than S subpopulation at different burial depths. The seedling emergence reached a maximum of 50% in the S subpopulation at a depth of 6.65 cm and in the R subpopulation at depths of 9.81 cm, respectively. Significant differences in seed germination were found between herbicide-resistant and susceptible sub population, and the pleiotropic effect of resistant alleles on germination and seed emergence under different environmental conditions was demonstrated. Results suggested that deep tillage operations and the delayed sowing of autumn-sown crops could control resistant populations that emerge more rapidly than S population; therefore, the prevalence in the R population may decrease. [ABSTRACT FROM AUTHOR]

The present study was planned to screen the sweet sorghum genotypes at the sensitive seedling stage against salinity with specific morpho-physiological and biochemical attributes that could contribute to their adaptability to salinity stress. Therefore, 14 sweet sorghum genotypes were subjected to five different NaCl salt concentrations (0 mM (C), 50 mM, 100 mM, 150 mM and 200 mM), and 5 days after germination (DAG), the seedlings were evaluated for morpho-physiological parameters (percent germination, shoot and root lengths, seedling biomass and seedling vigor indexes I and II), total sugars, total chlorophyll and Na+/K+ ratio. Correlation, heat map and principle component analysis revealed that germination percentage is highly correlated with seedling vigor indexes (I and II) and seedling fresh weight. The sweet sorghum genotypes showed a significant reduction in morpho-physiological traits with a minimum effect seen in PHULE VASUNDHARA and SSV 84 with increasing salt stress. Two clusters were obtained on the basis of all studied traits: in cluster I, PHULE VASUNDHARA and SSV 84 with better seedling growth, biochemical parameters (total sugars and total chlorophyll) and higher K+ concentration were grouped together and in cluster II, 12 genotypes were clustered together. Further, gene expression analysis of ion transporters (HKT-6 and HAK) confirmed the observed lower Na+/K+ ratio due to more HKT-6 ion transporter gene expression in the roots of the selected tolerant PHULE VASUNDHARA as compared to the selected sensitive SPV 2074 with more expression of ion transporter HAK, suggesting that this Na+/K+ ratio could be a reliable trait for salinity tolerance screening at seedling growth stage. Further, tolerant genotypes could be a prominent resource for further use in salinity tolerance breeding of sweet sorghum. [ABSTRACT FROM AUTHOR]

Soil salinization has become a major environmental and socioeconomic issue. Excessive accumulation of salts usually goes beyond the tolerance of most plants, except for halophytes that can thrive in saline environments. Despite this, establishment is still a crucial stage, often hindering the use of these species in degraded soils. Preconditioning to stress seems a simple method to overcome this limitation, but its potential and the mechanisms involved are still scarcely known. This study investigated if saline preconditioning can indeed enhance tolerance, using Casuarina glauca saplings (preconditioned and non-preconditioned) subjected to salt stress for 12 months. We found that preconditioning promoted stronger tolerance to salt stress, improving gas exchange parameters, intrinsic water-use efficiency, and chlorophyll content. The decrease in leaf osmotic potentials was higher in preconditioned than in non-preconditioned saplings. The osmotic potential at full turgor (Ψπ100) decreased in preconditioned plants by 47% and in non-preconditioned by 29%, and the osmotic potential at zero turgor (Ψπ0) decreased by 17% in preconditioned plants and by 4% in non-preconditioned compared to the control, indicating that the preconditioning promotes cellular osmotic adjustment and protects leaf membrane cells against leakage induced by salinity. Results also showed an increase in secondary metabolism as shown by the enhancement of phenolic content and in the expression of salt tolerance-related genes, particularly in preconditioned plants. This suggests the potential for oxidative stress signaling and reactive oxygen species (ROS) detoxification, which are essential components of stress tolerance mechanisms. Overall, C. glauca is highly suitable to be used on salinity-affected soils and can develop a higher tolerance to salt stress after preconditioning treatments. [ABSTRACT FROM AUTHOR]

Salt stress cause enormous loss in crop productivity and yield around the globe, which jeopardizes agro-ecosystem, and significantly affects food production. Wheat is consumed all over the world, but is highly susceptible under salt stress conditions. In the present study, we investigated the independent and co-application of γ-aminobutyric acid (GABA) and potassium (K) to counteract salt-induced tolerance mechanisms, growth attributes and yield traits. Both GABA and K play indispensable roles in counteracting the deleterious impacts of oxidative stress indicators with activated defense mechanisms (ascorbate–glutathione pathway and glyoxalase system), improved nitrogen and carbon assimilation, and photosynthesis-related traits in salt stressed wheat plants. Moreover, GABA and K application induced considerable changes in osmolyte concentration, stomatal dynamics, and improved yield traits under salt stress in wheat plants. Overall, current study showed the significant outcomes of co-application of GABA and K in alleviating salt stress-induced adversities in wheat, and could be manipulated for developing salt tolerant wheat plants. [ABSTRACT FROM AUTHOR]

The ability of endophytes to confer plant stress resistance opens a new avenue for mitigating the negative impact of various stresses on crop production. Consequently, the purpose of this study was to investigate plant growth-promoting nodule endophytes for alleviating salt stress in groundnut. Under salt-stressed conditions, rhizobial isolates (Rhizobium phaseoli S18 and Rhizobium pusense S6R2) and passenger endophytes (Pantoea dispersa YBB19B and Bacillus tequilensis NBB13) exhibited multiple plant growth-promoting traits, including IAA, siderophore production, nutrient solubilisation, and ACC deaminase, and compared to the control, the co-inoculation of Rhizobium pusense S6R2 and Bacillus tequilensis NBB13 produced the highest number of nodules (18 per plant) in saline soil. Analysis of root exudates revealed the presence of acetic acid, phenol, and succinic acid compounds in groundnut treated with Rhizobium pusense S6R2 + Pantoea dispersa YBB19B might have resulted in an enhanced stress tolerance mechanism in groundnut. In a pot culture experiment, the combined application of Rhizobium pusense S6R2 and Pantoea dispersa YBB19B or Bacillus tequilensis NBB13 increased plant growth, pod yield, production of anti-oxidant enzymes such as catalase and ascorbate peroxidase, and resulted in accumulation of osmolytes. Similarly, in the field experiment, the co-inoculation of Rhizobium pusense S6R2 and Pantoea dispersa YBB19B resulted in the highest groundnut yield in comparison to the other treatments. This study demonstrated that plants co-inoculated with Rhizobium pusense S6R2 and Pantoea dispersa YBB19B alleviated salt stress; consequently, they may be recommended as a bio-inoculant for salt stress alleviation in groundnut following field evaluation at multi locations. [ABSTRACT FROM AUTHOR]

Apocyni Veneti Folium (AVF) is a salt-tolerant medicinal halophyte and soil salinity is a main stress affecting its quality. Molecular bases involved in quality evaluation and ecological adaptations to abiotic constraints can be explored using omics tools. In the study, AVF was treated with four levels of salt stress (control, 100, 200 and 300 mM NaCl, respectively) and subjected to de novo-based RNA-sequencing. We constructed GO and KEGG analysis on the obtained DEGs. After molecular phylogenetic analysis, we isolated and characterized one representative and up-regulated candidate gene AvUGT (Tr_AVENL_25169) encoding UDP-glucosyltransferase under salt stress. Results showed that the obtained clean reads were assembled into a total of 54,276 high-quality unigenes. Notably, specific genes related to flavonoid glucoside biosynthesis and salt-tolerant regulation, such as genes encoding transcription factors, transporters, glucosyltransferase, heat shock protein and plant hormone signal transduction-related protein, preferentially up-regulated by low level of salt. Combined with previous metabonomic analysis, the results revealed key genes that contribute to elucidate the reduced salt toxicity in AVF. Furthermore, the transcript profiles of UGT genes were consistent with the accumulation of flavonoid glycosides in AVF; the candidate gene AvUGT probably plays a critical role in biosynthesis of flavonoid glucosides in response to salt environment. These results provided a basis for future research on the regulatory mechanism of salt stress of medicinal halophyte AVF. [ABSTRACT FROM AUTHOR]

The C4 plants photosynthesize better than C3 plants especially in arid environment. As an attempt to genetically convert C3 plant to C4, the cDNA of decarboxylating C4 type NADP-malic enzyme from Zea mays (ZmNADP-ME) that has lower Km for malate and NADP than its C3 isoforms, was overexpressed in Arabidopsis thaliana under the control of 35S promoter. Due to increased activity of NADP-ME in the transgenics the malate decarboxylation increased that resulted in loss of carbon skeletons needed for amino acid and protein synthesis. Consequently, amino acid and protein content of the transgenics declined. Therefore, the Chl content, photosynthetic efficiency (Fv/Fm), electron transport rate (ETR), the quantum yield of photosynthetic CO2 assimilation, rosette diameter, and biomass were lower in the transgenics. However, in salt stress (150 mM NaCl), the overexpressers had higher Chl, protein content, Fv/Fm, ETR, and biomass than the vector control. NADPH generated in the transgenics due to increased malate decarboxylation, contributed to augmented synthesis of proline, the osmoprotectant required to alleviate the reactive oxygen species-mediated membrane damage and oxidative stress. Consequently, the glutathione peroxidase activity increased and H2O2 content decreased in the salt-stressed transgenics. The reduced membrane lipid peroxidation and lower malondialdehyde production resulted in better preservation, of thylakoid integrity and membrane architecture in the transgenics under saline environment. Our results clearly demonstrate that overexpression of C4 chloroplastic ZmNADP-ME in the C3 Arabidopsis thaliana, although decrease their photosynthetic efficiency, protects the transgenics from salinity stress. [ABSTRACT FROM AUTHOR]

Key message: Nitraria sibirica Pall. regulates its tolerance to salt stress mainly by adjusting ion balance, modifying cell wall structure, and activating signal transduction pathways. N. sibirica, as a typical halophyte, can not only effectively restore saline-alkali land, but also has high economic value. However, studies on its salt tolerance at combining molecular and physiological levels were limited. In this study, the salt tolerance of N. sibirica was analyzed based on Pacbio full-length transcriptome sequencing, and the salt tolerance in the physiological level was verified by key genes. The results showed that 89,017 full-length transcripts were obtained, of which 84,632 sequences were annotated. A total of 86,482 coding sequences (CDS) were predicted and 6561 differentially expressed genes (DEGs) were identified. DEGs were significantly enriched in "sodium ion homeostasis", "response to osmotic stress", "reactive oxygen species metabolic process", "defense response by cell wall thickening", "signal transduction", etc. The expression levels for most of these DEGs increased under salt stress. A total of 69 key genes were screened based on weighted gene co-expression network analysis (WGCNA), of which 33 were first reported on salt tolerance. Moreover, NsRabE1c gene with the highest expression level was selected to verify its salt tolerance. Over-expression of NsRabE1c gene enhanced the germination potential and root length of transgenic Arabidopsis thaliana plants without salt treatment as compared to those of Col-0 and AtRabE1c mutant. The expression levels of NsRabE1c decreased in the growth stagnation phase, while significantly increased in the growth recovery phase under salt stress. We predicted that NsRabE1c gene help N. sibirica resist salt stress through the regulation of plant growth. The results of this study deepen the understanding of salinity resistance in N. sibirica. [ABSTRACT FROM AUTHOR]

Salinity is among major environmental constraints in arid and semi-arid regions of the world that is deteriorating soil fertility and reducing uptake of micronutrients especially Fe and Zn. The crop plants grown in calcareous and high pH soils are inherently low in these mineral nutrients. Wheat (Triticum aestivum L.) is the principal diet for almost one third of world's population. The information regarding the fortification of wheat with Fe and Zn under saline conditions is limited. The soil and foliar application of Fe and Zn may be helpful for improving the nutritional quality of wheat produced from salt-affected land. The aim of present study was to assess the responses of selected wheat cultivars (Faisalabad-2008 and Galaxy-2013) to soil and foliar application of Fe and Zn under saline conditions. Foliar and soil application of Fe and Zn was done individually as well as in combination. The experimental units were replicated thrice in Completely Randomized Design (CRD). The data of various wheat growth, ionic and biochemical parameters including grain yield, total chlorophyll contents, root and shoot length, root and shoot dry weights, Zn, Fe, K, and Na, SOD and CAT enzyme activity were recorded using standard procedures. It was clearly depicted by the results that the presence of salt stress in the growth medium significantly (p ≤ 0.05) deteriorated plant growth and yield. Also, the results showed that Zn and Fe application significantly (p ≤ 0.05) increased wheat plant growth under salt stress. The foliar application proved to be more efficient than soil application. However, the plants that contained combined application (soil and foliar) of Fe and Zn gave maximum yield as well as higher accumulation of Fe, Zn, and K in shoot and grains. It was, therefore, concluded that the combined soil and foliar application of Fe and Zn is an effective strategy to ameliorate micronutrients (Fe and Zn) deficiency in crops grown under salt-affected soil conditions. [ABSTRACT FROM AUTHOR]

Salt stress is one of the major prevalent abiotic stresses. Sorghum is an important fodder crop with considerable tolerance towards salinity. The presence of high genetic variability among sorghum genotypes can be used to obtain the most salt-tolerant genotypes for future perspective. Therefore, the present study was undertaken to assess the effect of different NaCl concentrations (0 mM, 25 mM, 75 mM, 100 mM, 125 mM, 150 mM, 175 mM and 200 mM) on the physiological parameters of twenty sorghum genotypes. The screening was carried out for germination per cent, shoot length, root length, seedling fresh weight, seedling dry weight, and germination speed and salinity tolerance indices under laboratory conditions. A significant reduction in all the growth parameters was observed with increasing salinity concentrations. Data assessment was done based on two-way ANOVA and hierarchical cluster analysis. On the basis of cluster analysis and salinity tolerance indices, genotype SSG-59-3, 2077A, HC308 and PSC1 were assessed as tolerant and SGL87 and NSS1005 as sensitive towards a higher level of salinity stress. [ABSTRACT FROM AUTHOR]

Soil salinity is one of the most challenging issue for sustainable crop productivity worldwide, and kenaf is an important natural fiber crop with considerable salt tolerance. However, little is known about the molecular mechanisms in kenaf salt tolerance. In this study, 60 kenaf cultivars were screened for salt tolerance, and after analysis of agronomic and physiological indexes, cultivar CP018 and CP047 were found to have the highest and the lowest salt tolerance, respectively. This was mainly demonstrated in the lower root MDA content of 26.78% in CP018 compared to 29.76% in CP047, while the enzyme activities of SOD, POD, and CAT were mostly higher in CP018 than in CP047. Then using these two cultivars CP018 and CP047 as representing salt-tolerant and salt-sensitive cultivars, further global gene expression analysis responses to salt stress were conducted under control (0-mM NaCl) and salt stress (200-mM NaCl) conditions. The result indicated 11,677 (6538 up- and 5139 down-regulated) and 11,764 (6159 up- and 5605 down-regulated) differentially expressed genes (DEGs) in CP018 and CP047, respectively. Transcription factors including WRKY, LBD, HSF, and NAC, most of which were up-regulated in CP018 compared with CP047. KEGG enrichment analysis identified significantly different gene expression related to metabolic pathways, such as ROS scavenging, sucrose and starch metabolism, plant hormone signal transduction, cysteine and methionine metabolism, phenylpropane, and flavonoid biosynthesis in both cultivars, and these pathways may be partly responsible for the differences in salt tolerance between CP018 and CP047. These findings may help to elucidate the molecular mechanisms of salt tolerance in kenaf. [ABSTRACT FROM AUTHOR]

Soil salinity stress is one of the major bottlenecks for crop production. Although, allantoin is known to be involved in nitrogen metabolism in plants, yet several reports in recent time indicate its involvement in various abiotic stress responses including salinity stress. However, the detail mechanism of allantoin involvement in salinity stress tolerance in plants is not studied well. Moreover, we demonstrated the role of exogenous application of allantoin as well as increased concentration of endogenous allantoin in rendering salinity tolerance in rice and Arabidopsis respectively, via., induction of abscisic acid (ABA) and brassinosteroid (BR) biosynthesis pathways. Exogenous application of allantoin (10 µM) provides salt-tolerance to salt-sensitive rice genotype (IR-29). Transcriptomic data after exogenous supplementation of allantoin under salinity stress showed induction of ABA (OsNCED1) and BR (Oscytochrome P450) biosynthesis genes in IR-29. Further, the key gene of allantoin biosynthesis pathway i.e., urate oxidase of the halophytic species Oryza coarctata was also found to induce ABA and BR biosynthesis genes when over-expressed in transgenic Arabidopsis. Thus, indicating that ABA and BR biosynthesis pathways were involved in allantoin mediated salinity tolerance in both rice and Arabidopsis. Additionally, it has been found that several physio-chemical parameters such as biomass, Na+/K+ ratio, MDA, soluble sugar, proline, allantoin and chlorophyll contents were also associated with the allantoin-mediated salinity tolerance in urate oxidase overexpressed lines of Arabidopsis. These findings depicted the functional conservation of allantoin for salinity tolerance in both plant clades. Key message: Phytohormonal pathways (abscisic acid and brassinosteroid) are involved in allantoin mediated salinity stress tolerance response in both monocot and dicot. [ABSTRACT FROM AUTHOR]

Compatible solutes can reduce the impact of salt stress on bacteria. This work describes the changes in Lactobacillus delbrueckii subsp. bulgaricus 3 (L. bulgaricus 3) cell morphology, viability, cell membrane permeability, Zeta potential, and fluidity under salt stress. The results showed that compatible solutes shortened the transition of bacterial cells to the stationary phase under salt stress from 25 to 22 h. The cell diameter decreased from 831 to 515 nm. Compatible solutes increased the number of bacteria and promoted cell growth. The number of viable bacteria increased from 4.33 × 106 to 5.71 × 108 CFU/mL. Application of compatible solutes also improved stability of the cell membrane and maintained integrity under salt stress. According to the results of fluorescence anisotropy analysis, compatible solutes increased the fluidity of the cell membrane under salt stress. These observations suggested that compatible solutes could decrease cell growth inhibition under salt stress by changing cell morphology and the cell membrane properties. [ABSTRACT FROM AUTHOR]

The effect of salt stress on Triticum aestivum L. plants inoculated with endophytic strains of B. subtilis was studied. The treatment of Triticum aestivum L. with endophytic bacterial strains of B. subtilis was shown to increase plant resistance to the stress factor. The inoculation reduced the development of oxidative stress and the entry of sodium ions into aboveground plant organs. The antistress effect of endophytic strains of B. subtilis and their ability to reduce the absorption of sodium ions by Triticum aestivum L. plants can be employed to promote plant growth during cultivation of crops on saline lands. [ABSTRACT FROM AUTHOR]

Biochar-based nanocomposites (BNCs) with a high level of sodium sorption capacity may improve salinity tolerance and seedling establishment of dill. Thus, a pot experiment was conducted to evaluate the effects of solid biochar (30 g solid biochar kg−1 soil) and biochar-based nanocomposites of iron (BNC-FeO) and zinc (BNC-ZnO) in individual (30 g BNC kg−1 soil) and a combined form (15 g BNC-FeO + 15 g BNC-ZnO kg−1 soil) on dill seedling growth in different levels of salt stress (non-saline, 6 and 12 dSm−1). Salinity caused a decrease in emergence percentage and emergence rate of seedlings. Increasing salinity of soil up to 12 dSm−1 decreased the biomass of dill seedlings by about 77%. Application of biochar and particularly BNCs increased the content of potassium, calcium, magnesium, iron, and zinc, reducing and non-reducing sugars, total sugars, invertase and sucrose synthase activities, leaf water content, gibberellic acid, and indole-3-acetic acid in dill plants, leading to an improvement in seedling growth (shoot length, root length, and dry weight) under saline conditions. Sodium content was noticeably decreased by BNC treatments (9–21%), which reduced mean emergence rate and stress phytohormones such as abscisic acid (31–43%), jasmonic acid (21–42%), and salicylic acid (16–23%). Therefore, BNCs especially in combined form can potentially improve emergence and growth of dill seedlings under salt stress, through reducing sodium content and endogenous stress hormones, and enhancing sugars and growth promoting hormones. [ABSTRACT FROM AUTHOR]

Constructed wetland (CW), an ecological water treatment system, can purify and repair the damaged saline water body in an open watershed, but its repairing function is limited at low temperature under salt stress. In this study, two different plant species with slag-sponge layer were operated to enhance the purification effect of CW on the damaged saline water body. The results showed that the combination of Scirpus mariqueter and slag-sponges in CW had a better purification effect especially under the condition of salinity of 10‰ (S = 10) with a respective removal efficiency of 91.04% of total nitrogen, 80.07% of total phosphorus, and 93.02% of COD in high temperature (25 ~ 35 °C). Furthermore, ecological traits (enzyme activity and amino acids) of plants, the abundance and distribution of functional microorganisms on the surface of slag-sponges, and the microbial state on the substrate surface of the denitrifying zone of CW were analyzed to explain how exactly the combinations worked. It was found that the enrichment of functional microorganisms in slag-sponge and the anaerobic zone of plants have improved the nitrogen and phosphorus removal. Plants maintained high enzyme activities and the ability to synthesize key amino acids under salt stress to ensure the growth and reproduction of plants and achieve the assimilation function. Scirpus mariqueter combined with slag-sponges in CW effectively improved the purification effect of damaged saline water, indicating that it is an ecological and green saline water treatment way. [ABSTRACT FROM AUTHOR]

SINA (Seven in absentia) proteins in the subtype of E3 ubiquitin ligase family play a crucial role in plant growth and development. However, their functions in response to salt and osmotic stresses in oil crops are still largely unknown. In this study, a total number of 23 BnaSINAs were identified in the rapeseed genome. Chromosome location and collinear relationship analyses revealed that they were unevenly distributed on 13 chromosomes, and have gone through 22 segmental duplication events under purifying selection. Phylogenetic and gene structural analyses indicated that they belonged to five main groups, and those in the same subgroup showed similar gene structure. All BnaSINAs were predicted to form homo- or heterodimers. Except BnaSINA7, BnaSINA11, BnaSINA17 and BnaSINA18, which lacked the N-terminal RING finger, all BnaSINAs contained a conserved C-terminal SINA domain, a typical structural feature of the RING-type E3 ligase family. Transcriptional expression analyses demonstrated that most BnaSINAs were ubiquitously expressed in roots, stems, leaves, flowers, pods and seeds, and all were responsive to salt and osmotic stresses. Further, yeast two-hybrid and Arabidopsis mutant complementation analyses demonstrated that BnaSINA4 interacted with BnaSINA17 to form heterodimer, and expression of BnaSINA17 in the Arabidopsissina2 mutant restored its growth resistance to salt and osmotic stresses. Our findings provide an important genetic foundation for the functional elucidation of BnaSINAs and a novel gene resource for the breeding of new oil crop cultivars with improved abiotic stress resistance. [ABSTRACT FROM AUTHOR]

Increased soil salinization is among the main factors that limits safe rice production. Arbuscular mycorrhizal fungi (AMF) have been shown to alleviate the toxic effects of salt stress in plants. However, more studies on AMF combined with other functional microorganisms are needed to further improve salt tolerance in rice. Therefore, the compound inoculum Funneliformis mosseae (Fm) together with two functional microorganisms, Piriformospora indica (Pi) and Agrobacterium rhizogenes (Ar) was evaluated for their effect on the rice growth, photosynthetic gas exchange parameters, ion homeostasis, and the expression of salt tolerance-related genes under 0, 80, 120 and 160 mM salt stress conditions. The results showed that: (1) the rice seedling biomass of the AMF compound inoculant treatment group was significantly higher than that of the non-inoculation treatment group (P < 0.05); (2) under NaCl stress, inoculation with AMF compound inoculants can activate the rice antioxidant enzyme system and improve osmoregulation ability; (3) AMF compound inoculants can increase the concentration of K+ in the plant and inhibit the transfer of Na+ to rice leaves, maintaining a high K+/Na+; and (4) AMF compound inoculants could induce and regulate the overexpression of genes related to salt tolerance, photosynthesis and ion homeostasis in rice, and improve the tolerance of rice under salt stress. Our study showed that AMF compound inoculants could improve the adaptability of rice under NaCl stress and promote plant growth by regulating the photosynthetic gas exchange parameter, reactive oxygen species (ROS) scavenging ability, and ion homeostasis of plants. These results suggest that AMF compound inoculants may play an important role in improving rice productivity in salinized soil. [ABSTRACT FROM AUTHOR]

Droplet digital PCR (ddPCR) is being increasingly adopted for gene detection and quantification because of its higher sensitivity and specificity. According to previous observations and our laboratory data, it is essential to use endogenous reference genes (RGs) when investigating gene expression at the mRNA level under salt stress. This study aimed to select and validate suitable RGs for gene expression under salt stress using ddPCR. Six candidate RGs were selected based on the tandem mass tag (TMT)-labeled quantitative proteomics of Alkalicoccus halolimnae at four salinities. The expression stability of these candidate genes was evaluated using statistical algorithms (geNorm, NormFinder, BestKeeper and RefFinder). There was a small fluctuation in the cycle threshold (Ct) value and copy number of the pdp gene. Its expression stability was ranked in the vanguard of all algorithms and was the most suitable RG for quantification of expression by both qPCR and ddPCR of A. halolimnae under salt stress. Single RG pdp and RG combinations were used to normalize the expression of ectA, ectB, ectC and ectD under four salinities. The present study constitutes the first systematic analysis of endogenous RG selection for halophiles responding to salt stress. This work provides a valuable theory and an approach reference of internal control identification for ddPCR-based stress response models. [ABSTRACT FROM AUTHOR]

Key message: PvLBD12 enhanced the salt tolerance by increasing proline accumulation, improving K+ accumulation, and decreasing reactive oxygen species level in switchgrass. Abiotic stresses are the serious factors which limit plant development and productivity and restrict the agricultural economy. It is important, therefore, to understand the mechanism of abiotic tolerance in plants. Lateral organ boundaries domain (LBD) proteins as plant-specific transcription factors play important function in plant lateral organ development, plant regeneration, and abiotic stress. In our study, we identify 69 LBD members from switchgrass genome-wide sequences and classify them based on their homology with LBD proteins in Arabidopsis. RT-qPCR showed that PvLBD genes had different expression patterns under abiotic stress conditions, indicating that they play important roles in various stress. PvLBD12 was selected as a candidate gene for further functional analysis because it had the highest expression level under salt stress. Overexpression of PvLBD12 enhanced salt tolerance by altering a wide range of physiological responses (like increased proline accumulation, reduced malondialdehyde production, improved K+ accumulation, and reduced Na+ absorption) in switchgrass. Some stress response genes such as proline biosynthesis gene PvP5CS1, vacuolar Na+(K+)/H+ antiporter gene PvNHX1, two key ROS-scavenging enzyme genes PvCAT and PvSOD were all upregulated in PvLBD12 overexpression lines. Taken together, PvLBD12 plays a pivotal role in response to salt stress by increasing proline accumulation, improving K+ accumulation, reducing Na+ absorption, and decreasing reactive oxygen species level. It will be better to understand the potential biological functions of LBD genes in other plants. [ABSTRACT FROM AUTHOR]

Rice is a major cereal that nourishes more than half of the global population. But rice lands are under threat from soil salinity leading to reduced productivity. Salinity stress tolerance is challenging due to the multigenic trait and complex tolerance mechanisms. QTL pyramiding is one of the efficient approaches to stack desired genes and QTLs from multiple donors. This study developed three populations using multiple salt-tolerant introgression lines (ILs) to accumulate beneficial alleles/QTLs and identify improved salt-tolerant breeding lines. To accumulate the salt-tolerant alleles from salt-tolerant donors, we used salt-tolerant ILs of Pokkali and Nona Bokra in the CL151 background (CLPK683 and CLPK757) and Jupiter background (JN100 and JN520), respectively. The QTLs for shoot Na+ and K+ content, qNa2.2, qK2.1, and qK2.2, from JN100 and qK4.1 and qK8.1 from JN520 were targeted using the molecular markers linked to these QTLs. Both phenotypic and genotypic selection methods were employed to advance the populations. The F5 populations of each cross were finally evaluated for seedling-stage salt tolerance. The visual salt injury score (SIS) and shoot Na+ and K+ concentration in selected lines indicated salt tolerance higher than the IL parents. The targeted QTLs were detected in most salt-tolerant lines. The salt-tolerant breeding lines identified in this study constitute a valuable resource for investigating the physiological and molecular basis of salt tolerance and identifying superior alleles of salt-tolerance genes for use in breeding programs. [ABSTRACT FROM AUTHOR]

Main conclusion: Enhanced secretion of Na+ and Cl− in leaf glands and leaf vacuolar sequestration of Na+ or root retention of Cl−, combined with K+ retention, contribute to the improved salt tolerance of tetraploid recretohalophyte P. auriculata. Salt stress is one of the major abiotic factors threatening plant growth and development, and polyploids generally exhibit higher salt stress resistance than diploids. In recretohalophytes, which secrete ions from the salt gland in leaf epidermal cells, the effects of polyploidization on ion homeostasis and secretion remain unknown. In this study, we compared the morphology, physiology, and ion homeostasis regulation of diploid and autotetraploid accessions of the recretohalophyte Plumbago auriculata Lam. after treatment with 300 mM NaCl for 0, 2, 4, 6, and 8 days. The results showed that salt stress altered the morphology, photosynthetic efficiency, and chloroplast structure of diploid P. auriculata to a greater extent than those of its tetraploid counterpart. Moreover, the contents of organic osmoregulatory substances (proline and soluble sugars) were significantly higher in the tetraploid than in the diploid, while those of H2O2 and malondialdehyde (MDA) were significantly lower. Analysis of ion homeostasis revealed that the tetraploid cytotype accumulated more Na+ in stems and leaves and more Cl− in roots but less K+ loss in roots compared with diploid P. auriculata. Additionally, the rate of Na+ and Cl− secretion from the leaf surface was higher, while that of K+, Mg2+, and Ca2+ secretion was lower in tetraploid plants. X-ray microanalysis of mesophyll cells revealed that Na+ mainly accumulated in different cellular compartments in the tetraploid (vacuole) and diploid (cytoplasm) plants. Our results suggest that polyploid recretohalophytes require the ability to sequester Na+ and Cl−(via accumulation in leaf cell vacuoles or unloading by roots) and selectively secrete these ions (through salt glands) together with the ability to prevent K+ loss (by roots). This mechanism required to maintain K+/Na+ homeostasis in polyploid recretohalophytes under high salinity provides new insights in the improved maintenance of ion homeostasis in polyploids under salt stress. [ABSTRACT FROM AUTHOR]

Salinity is one of the major environmental constraint that restricts crop growth and yield. Rice (Oryza sativa L.), one of the major staple crops, consumed by more than half of the world's population is regarded to be salt sensitive. Salt stress in plants occurs in two phases over time, i.e. osmotic and ionic phase. The application of salt stress also plays an important role in deciding whether the crop is responding to salt stress or salt shock. Further, the response to salinity stress is specific to the crop developmental stage. Hence an experimental approach that takes into account these factors (1) delineating the two phases (2) salt stress vs salt shock and (3) developmental stage is crucial in exploring salt determinants in rice. The review presented here examines the data in these aspects and further, provides various approaches in light of the current understanding. The focus is on the different approaches available to researchers including Petri plate based method, hydroponics and soil based approaches for screening and understanding the plant response to salinity. The review will be helpful for researchers to choose an appropriate experimental procedure for studying tolerance to NaCl stress using rice as a model system in the laboratory. [ABSTRACT FROM AUTHOR]

Aims: Selenium (Se) has been reported to mitigate the harmful effects of salt stress on plants; however, the internal mechanisms remain unknown. Here, the effects of Se supplementation on tomato plants under salt stress were investigated. Methods: The biomass, relative electrical conductivity (REC), relative water content (RWC), photosynthetic parameter, inorganic ion contents, malondialdehyde (MDA), soluble sugar and proline contents, as well as the regulation of plant hormones of Se application in tomato plants were investigated after exposure to Se and salt stress treatments. Results: Exogenous Se application improved photosynthesis and the water use efficiency (WUE) of tomato plants under salt stress, thereby promoting the growth of tomato plants under salt stress. Se supplementation also maintained the K+ and Na+ homeostasis, reduced the REC, decreased MDA, H2O2 and O2•− contents, and mitigated the oxidative damage caused by salt stress. In addition, exogenous Se increased the salicylic acid (SA) content in tomato leaves and roots via up-regulating the PAL or ICS pathways involved in SA biosynthesis. After pre-treatment with the SA inhibitor 1-aminobenzotriazole, the photosynthetic efficiency of tomato plants decreased, plant growth was weakened, and the REC was increased, indicating that the alleviating role of Se on salt stress was abolished. Conclusions: Our results clarified the roles of Se and its regulation mechanisms in plant salt stress tolerance and the critical involvement of SA in this process. The study of Se in plant abiotic stress tolerance will give a more theoretical foundation for using exogenous Se in agricultural production to enhance crop growth and yield under adversity stresses. [ABSTRACT FROM AUTHOR]

Nitrogen pollution and excessive salinity are commonly regarded as one of the major environmental concerns in recent decades in many urban environments. Although in urban areas lichens are exposed to both salt and nitrogen stress, no studies have been conducted to date on the simultaneous impact and interaction of these factors on lichen physiology. The aim was to determine the effect of various combinations of NaCl and NH4NO3 doses on the physiology of epigeic lichen Cladonia rei. We also aimed to compare the response of lichens collected from polluted and unpolluted sites to verify whether lichens exposed to different levels of environmental stress in their native environment will react differently. The combined salt-nitrogen treatment caused significant disturbances in the integrity of cell membranes and chlorophyll fluorescence parameters. The most detrimental effect concerned the loss of cell membrane integrity, which suggests that this parameter can serve as a relevant indicator of acute salt-nitrogen stress incidents. Salt stress decreased the photosynthetic efficiency 1 h after exposure, but after 72 h, the FV/FM returned to the level characteristic of healthy lichens in experimental groups without and with small doses of ammonium nitrate. In contrast, recovery was not possible in combination with high nitrogen doses. This indicates that exposure to short-term salt stress in a nitrogen-poor environment only causes a temporary reduction in photosynthetic efficiency, but in urban eutrophic environments may have more serious consequences. The weakened physiological condition of the mycobiont manifested by an increased level of cell membrane damage and a persistent decrease in the photosynthetic efficiency of the photobiont in lichens growing along the roads may indicate an excess of nitrogen in the environment, enhanced by the effect of salt. Lichens collected from a heavy-metal-polluted habitat responded more strongly than those from an unpolluted habitat suggesting that in lichens previously affected by certain harmful factors, exposure to another stress factor may lead to greater disturbances. This is of particular importance for lichens inhabiting the vicinity of roads, since they are also under the influence of other pollutants emitted by road traffic. [ABSTRACT FROM AUTHOR]

Background: Trichoderma viride are well known for their biocontrol capabilities, but little is known about how they stimulate plant development and increase their resistance to salt stress. One of the main abiotic factors limiting crop development and yield is salt stress. Therefore, the purpose of this work was to ascertain how NaCl effects on T. viride growth as well as on the seedlings morphological and physio-biochemical parameters of tomato (Solanum lycopersicum L.) under plate culture conditions. Additionally, a pot experiment was conducted to determine how T. viride affected the development characteristics of tomato plants subjected to various salt concentrations (50 and 100 mM NaCl). T. viride's contribution to tomato seedling stress tolerance was also closely examined. Results: Results showed that 100 mM NaCl decreased the colony diameter of T. viride by 13.4% compared to the control. Under plate and greenhouse conditions, tomato seedlings exposed to salt exposure exhibited an overall decline in growth. Also, a reduction in relative water content (RWC) and protein contents occurred under salt stress. At the same time, increases were found in proline, total phenolics, flavonoids, H2O2 content, malondialdehyde, likewise the activities of peroxidase (POD), catalase (CAT), polyphenol oxidase (PPO), and ascorbate peroxidase (APX) enzymes. Even though, with T. viride application, the salt negative effects on both morphological and physio-biochemical parameters were mitigated to a greater extent. T. viride increased proline and total antioxidant capacity (TAC) in tomato seedlings at 100 mM NaCl by an average of 20.66 and 43.82% compared to their comparable control. T. viride increased the activities of CAT, PPO, and APX enzymes by 74.6, 58.48, and 61.61% at 50 mM NaCl compared to non-saline control seedlings. As well, T. viride decreased MDA and H2O2 contents by an average of 14 and 24.8% in tomato seedlings at 50 mM NaCl compared to their comparable control. Also, under 100 mM NaCl, the T. viride-treated tomato seedlings showed increased total phenolics (17.85%) and flavonoids (33.17%) compared to non- treated one. Conclusion: Hence, our research sheds new insight on the pathways by which T. viride can boost tomato seedling tolerance to salt stress at morphological and physio-biochemical levels by activating both enzymatic and non-enzymatic antioxidant defense systems. [ABSTRACT FROM AUTHOR]

Bacteria isolated from extreme environments have been shown to promote plant growth under challenging conditions. This study aimed to examine the performance of the extremophilic microorganisms under salt stress and their ability to improve the tolerance of soybean plants to this stress. In vitro experiments showed that bacteria belonging to the genera Stenotrophomonas and Exiguobacterium were halophilic and displayed plant growth-promoting activities under salt stress. For instance, these two species enhanced soybean germination rate between 35 and 43% in comparison with non-inoculated seeds. In addition, inoculation allowed soybean roots to double their size, both in length and in dry biomass, under 250 mM NaCl. The plant physiological responses correlated with changes in plant gene expression during developmental and stress responses. The expression of a growth marker gene (Glyma.03G226000) increased in the presence of halophilic bacteria both under salt stress (5- to 24-fold) and under non-stress conditions (17- to 25-fold). Soybean genes responsive to stress, such as Glyma.02G228100, Glyma.04G180400, Glyma.08G189600, and Glyma.17G173200, were highly induced by salt in bacteria-inoculated roots. This work showed that the extremophilic bacteria used in these experiments could be used as potential bio-inoculants to help alleviate salt stress and plant growth. [ABSTRACT FROM AUTHOR]

Main conclusion: A lncRNA MtCIR1 negatively regulates the response to salt stress in Medicago truncatula seed germination by modulating seedling growth and ABA metabolism and signaling by enhancing Na+ accumulation. Increasing evidence suggests that long non-coding RNAs (lncRNAs) are involved in the regulation of plant tolerance to varying abiotic stresses. A large number of lncRNAs that are responsive to abiotic stress have been identified in plants; however, the mechanisms underlying the regulation of plant responses to abiotic stress by lncRNAs are largely unclear. Here, we functionally characterized a salt stress-responsive lncRNA derived from the leguminous model plant M. truncatula, referred to as MtCIR1, by expressing MtCIR1 in Arabidopsis thaliana in which no such homologous sequence was observed. Expression of MtCIR1 rendered seed germination more sensitive to salt stress by enhanced accumulation of abscisic acid (ABA) due to suppressing the expression of the ABA catabolic enzyme CYP707A2. Expression of MtCIR1 also suppressed the expression of genes associated with ABA receptors and signaling. The ABA-responsive gene AtPGIP2 that was involved in degradation of cell wall during seed germination was up-regulated by expressing MtCIR1. On the other hand, expression of MtCIR1 in Arabidopsis thaliana enhanced foliar Na+ accumulation by down-regulating genes encoding Na+ transporters, thus rendering the transgenic plants more sensitive to salt stress. These results demonstrate that the M. truncatula lncRNA MtCIR1 negatively regulates salt stress response by targeting ABA metabolism and signaling during seed germination and foliar Na+ accumulation by affecting Na+ transport under salt stress during seedling growth. These novel findings would advance our knowledge on the regulatory roles of lncRNAs in response of plants to salt stress. [ABSTRACT FROM AUTHOR]

The existing data on the role of PTF1/TCP13 belonging to the TCP family of transcription factors in regulating expression of a psbD plastid gene encoding a D2 protein of PSII are controversial. To analyze biological functions of PTF1/TCP13, transformed plants expressing PTF1/TCP13 under a β-estradiol-inducible promoter were used. PTF1/TCP13 overexpression did not provide the expected increase in the accumulation of psbD transcripts transcribed from BLRP (Blue Light Responsive Promoter), though their level significantly increased under exposure to light or abscisic acid (ABA). PTF1/TCP13 was up-regulated by ABA; moreover, genes of the canonic pathway of the ABA signal transduction were involved in the regulation of PTF1/TCP13 expression. In addition, PTF1/TCP13 was induced in response to salt stress However, in the overexpressing line, salt tolerance and expression of salt stress markers, as well as a number of genes for the synthesis and signaling of ABA, were reduced compared to plants with the normal level of expression of this transcription factor, that is, PTF1/TCP13 acted as a negative regulator of salt stress Thus, PTF1 does not belong to plastid transcription factors. Nevertheless, it represents one of the components of the ABA-dependent regulatory chain capable of modifying expression of nuclear and chloroplast genes in response to changes in homeostasis. [ABSTRACT FROM AUTHOR]

Seed priming has recently gained considerable attention to induce salt tolerance in several crop plants. In the present study, we evaluated the effect of seed priming with silicon (Si) using different concentrations (10, 20, and 40 mM) on barley (Hordeum vulgare L.) seed germination performance, seedling ion distribution, early growth establishment, and oxidative stress metabolism as grown under salinity (75 mM NaCl). Our results showed that all seed treatments (hydro-priming or Si-priming) improved salt tolerance of barley, relatively to unprimed state. However, specific differences associated with Si concentrations were recorded. At germination stage, a marked increase in germination percentage (100% on the 4th day of sowing) was recorded at 20 mM Si. When germination takes place in a salt-stressed medium, seedlings issued from seeds primed with 20 mM Si exhibited the highest ability to grow under saline conditions. Again, Si at 20 mM was the most beneficial for water adjustment in both roots (70%) and shoots (60%). This response was accompanied with increased root and shoot K+ content (33 and 25%, respectively). Seed priming with 20 mM Si resulted in a decrease in Na+ contents (by 42% in roots and 52% in shoots). This effect paralleled with a marked decline in H2O2 (by 65% in roots and 85% in shoots) and MDA content which together led to a spectacular activation of the overall antioxidant enzymes (SOD, CAT, and GPX). Taking into account these results, we suggest that the marked effectiveness of Si in primed seeds was more associated with ROS-scavenge and early activation of antioxidant defence, recorded in barley seedlings when subsequently grown under salinity stress. [ABSTRACT FROM AUTHOR]

Soil salinization has seriously affected plant growth and restricted economic development. Malus zumi is an excellent apple grafting rootstock, and it is also an important tree species to improve saline-alkali land. Under the stress of 200 mM NaCl, the yellowing of Malus zumi leaves became more obvious with time, the activities of antioxidant enzymes increased, and the chlorophyll content increased first and then decreased. Through transcriptome sequencing analysis, 426 new genes were found in a total of 37191 transcriptome sequences, and these new genes were still different from those of apple. After 48 hours of salt stress, compared with the untreated group, 4861 genes were differentially up-regulated and 4413 genes were differentially down-regulated. Through GO function enrichment analysis and pathway function enrichment analysis, it was found that salt stress affected the amino acid synthesis, metabolism, photosynthesis, and other related processes of Malus zumi. Analysis of differential transcription factors revealed that WRKY and ERF families were the important transcription factors involved in salt stress. The gene located at the key positions of metabolic pathway was verified by fluorescence quantitative PCR, and the results were consistent with the results of transcriptome sequencing, which proved the reliability of the data of differentially expressed genes. [ABSTRACT FROM AUTHOR]

Salinity affects the physiological activities of seagrass by changing the osmotic pressure of seagrass cells, which then affects the structure and function of seagrass community. In this study, we created transgenic Arabidopsis that overexpressed the ZjGRF1 gene from the intertidal seagrass Zostera japonica. We found that transgenic ZjGRF1 Arabidopsis has stronger tolerance to salt stress and osmotic stress than wild type. Under salt stress, the content of reactive oxygen species in transgenic ZjGRF1 Arabidopsis was lower than that in wild-type Arabidopsis. The viability of root cells in transgenic ZjGRF1 Arabidopsis was higher than that of wild type under salt stress. Under salt stress, transgenic ZjGRF1 Arabidopsis accumulated more proline and had higher antioxidant enzyme activities. The rate of water loss rate from overexpressed plants was lower than that of the wild-type plants. The resistance of overexpressed plants to osmotic stress may be enhanced by the ABA-dependent pathway. Our results confirm that ZjGRF1 enhances tolerance to salt and osmotic stress in Z. japonica. [ABSTRACT FROM AUTHOR]

Wheat is the second important cereal crop worldwide due to nutritional composition and role in meeting daily energy needs. Salinity is an abiotic stress factor that restricts crop productivity through influencing plant growth and development in arid and semi-arid regions. Nanomaterials and plant growth promoting bacteria (PGPBs) can be used in many different areas of agriculture for different purposes. In this study, changes in cytosine methylation and DNA damage levels in wheat (Triticum aestivum L.) exposed to salt stress (250 mM NaCl) were determined and possible preventive effects of copper (II) oxide nanoparticles (0, 50 and 100 mg/L; CuO-Nps > 100 nm) and plant growth promoting bacteria (no bacteria, Bacillus subtilis, Lactobacillus casei, Bacillus pumilis; PGPBs) treatments were investigated. Changes in cytosine methylation were analyzed by Coupled Restriction Enzyme Digestion-iPBS (CRED-iPBS) and genotoxic influences and genomic stability was analyzed with the aid of inter-primer binding site (iPBS) primers. Application of 250 mM NaCl remarkably increased polymorphism rate of iPBS profile. Besides, relieve effect of PGPBs with CuO-NPs was observed against adverse effect of 250 mM NaCl stress. The genomic template stability values clearly increased with PGPBs with CuO-NPs treatments, particularly Lactobacillus casei with 100 mg/L of CuO-Nps. In addition, DNA hypo-methylation was observed in all treatments. As a conclusion, PGPBs with CuO-NPs treatments showed a strong anti-genotoxic effect against NaCl stress and they could be used as an alternative molecule to alleviate genetic impairment in wheat under NaCl stress. [ABSTRACT FROM AUTHOR]

The circadian clock is a cell autonomously and endogenously regulated biological timekeeper that detects changes in environmental stimuli and generates 24-h rhythms that are synched with day to day and periodic oscillations to govern many biological functions. Plant's circadian clocks enable them to anticipate environmental changes by modifying their physiological and biological traits to improve plant fitness. The internal circadian clock not only aids fitness but also allows the plant to time-gate the response to environmental stimuli. The latest evidence on the circadian clock suggests that the clock regulates/modulates the expression of abiotic stress-responsive pathways to improve tolerance to stresses without hampering plant growth. In turn, stress signaling also influences the activity of several clock components. This review emphasizes the interplay of the biological circadian clock with abiotic stress-responsive pathways (drought, heat, cold, and salt) for plant growth and survival as well as for stress resilience. A better comprehension of these mechanisms could aid in the development of genetic tools to improve breeding procedures and plant stress tolerance, thereby increasing crop yield and quality under changing ecological conditions. [ABSTRACT FROM AUTHOR]

The involvement of ethylene in reversal of salt (NaCl; 50 mM) stress on photosynthetic activity and growth by salicylic acid (SA; 0.5 mM) together with sulfur (S; 2.0 mM) was studied in mustard (Brassica juncea L. cv. Pusa Vijay). Application of SA plus SO42− improved photosynthetic activity through markedly increased S-assimilation, strengthening antioxidant defense system and limiting NaCl-accrued oxidative consequences more conspicuously than their individual effect in B. juncea under 50 mM NaCl stress. Since SA acts as an inhibitor of ethylene and S-assimilation is associated with ethylene synthesis, we tried to figure out the interaction of ethylene in SA and SO42−-mediated salt tolerance. The involvement of ethylene was studied by supplementing salt-treated plants with 200 µL L−1 ethephon (an ethylene-releasing compound) or 100 µM norbornadiene (NBD, ethylene action inhibitor) to SA and SO42− treatments. Ethephon supplemented to NaCl-treated plants showed optimal ethylene formation, increasing ethylene sensitivity to enhance photosynthesis by affecting antioxidative capacity of plants. SA plus SO42− treatment decreased stress ethylene production and optimized ethylene formation under NaCl stress that contributed in the maintenance of high photosynthetic rate, which was reversed with NBD. NaCl-treated plants receiving SA plus SO42− and supplemented with NBD showed inhibited photosynthetic characteristics and growth, with minimal S-assimilation capacity, activity of antioxidant enzymes and GSH content. This showed that the reversal of salt stress by SA plus SO42− was through ethylene involvement. Overall, ethylene intervened the effect of SA in the presence of SO42− to induce S-assimilation, upregulated the enzymatic and non-enzymatic antioxidants, and imparted NaCl tolerance in plants. [ABSTRACT FROM AUTHOR]

Alfalfa (Medicago sativa L.) is one of the most valuable forage crops having an intermediate salt-tolerant level. In this fact, twelve selected alfalfa from the south Tunisia oasis were subjected to salt stress looking for their adaptability against these abiotic constraints. Hence, this work reports the sodium chloride effect (150 mM) on the basis of biomass yield reduction. For this, some cultural, physiological, and biochemical parameters were monitored. Indeed, the relative water content, the stem and leaves aspects, chlorophyll content, protein amount, free proline amount, K+ and Na+ concentrations, protease and α-amylase activities, superoxide dismutase, and catalase ones were monitored. The findings give rise to no significant salinity effect on stem length and leaf number. However, there was a significant difference in leaf color for plants under salt stress. In addition, salinity decreases both fresh and dry weight of all cultivars. NaCl treatment significantly reduced chlorophyll content and the K+ ion accumulations. Also, under salt stress, there was higher proline accumulation, Na+, and proteins in all alfalfa cultivars than under control. Additionally, these findings noticed the increase of enzymatic scavenging system related to the activity of superoxide dismutase, catalase, and protease under salt stress condition. In contrast, the α-amylase activity decreased under salt treatment. It seems from the studied parameters that our 12 alfalfa oasis cultivars are tolerant to salt stress under oasis conditions. [ABSTRACT FROM AUTHOR]

Polyploid species have played an essential role in plant evolution, exemplified by adaptive advantages to abiotic stress. N6-Methyladenosine (m6A) is suggested to play an important role in stress response. However, whether genome doubling affects m6A to increase autopolyploids stress tolerance is still unclear. This study aims to compare physiological (maintaining osmoregulatory homeostasis) and m6A changes between autotetraploid and diploid wild barley (Hordeum bulbosum) in response to salt (NaCl) stress. Results showed that autotetraploids physiologically had enhanced stress tolerance based on the measured parameters of relative water content, water loss, proline, H2O2, and chlorophyll. Diploid H. bulbosum experienced an excessive abundance of proline following salt stress where tetraploids had beneficial proline accumulation and thus enhanced osmoregulation. The significantly higher level of proline and H2O2 in diploid than in autotetraploid implies that diploids suffered higher osmotic stress than autotetraploid. Autotetraploid produced enough proline to protect stress, but not so much to cause toxicity. m6A in total RNA showed no significant difference between ploidies in controls, but was significantly higher in autotetraploids than in diploids during stress and recovery. These results suggest that increased m6A might be one of molecular mechanisms that increases salt tolerance in autotetraploid H. bulbosum compared to diploids, which enhances the adaptation of autopolyploids. [ABSTRACT FROM AUTHOR]

Salt stress poses physiological drought, ionic toxicity and oxidative stress to plants, which causes premature senescence and death of the leaves if the stress sustained. Salt tolerance varied between different rice varieties, but how different rice varieties respond at the early stage of salt stress has been seldom studied comprehensively. By employing third generation sequencing technology, we compared gene expressional changes in leaves of three rice varieties that varied in their level of tolerance after salt stress treatment for 6 h. Commonly up-regulated genes in all rice varieties were related to water shortage response and carbon and amino acids metabolism at the early stage of salt stress, while reactive oxygen species cleavage genes were induced more in salt-tolerant rice. Unexpectedly, genes involved in chloroplast development and photosynthesis were more significantly down-regulated in the two salt tolerant rice varieties 'C34' and 'Nona Bokra'. At the same time, genes coding ribosomal protein were suppressed to a more severe extent in the salt-sensitive rice variety 'IR29'. Interestingly, not only variety-specific gene transcriptional regulation, but also variety-specific mRNA alternative splicing, on both coding and long-noncoding genes, were found at the early stage of salt stress. In summary, differential regulation in gene expression at both transcriptional and post-transcriptional levels, determine and fine-tune the observed response in level of damage in leaves of specific rice genotypes at early stage of salt stress. [ABSTRACT FROM AUTHOR]

Salt stress is one of the leading growth-retarding factors among all the abiotic stresses that affect 30% of worldwide-irrigated land. Researchers are employing different strategies and approaches to manage this problem. However, some of the strategies are costly while others are time consuming. On the other hand, the use of endophytes is pragmatic, cheap and eco-friendly. This work investigated the potential role of endophytic Aspergillus oryzae CM1 in the mitigation of salinity-induced stress in Abelmoschus esculentus. NaCl stress altered the morphological and physio-biochemical attributes as well as phytohormones in okra plants. The inoculation of endophytic A. oryzae CM1 significantly increased growth attribute (shoot/root length), biomass (fresh/dry weight), chlorophyll (a, b) and carotenoids contents, IAA, total soluble sugar and relative water content (RWC) in okra. The malondialdehyde (MDA) and proline content in the okra seedlings increased by 91.21% and 38.83%, respectively. Increase in phenolic and flavonoid contents were witnessed in NaCl stressed okra plants inoculated with isolate CM1. NaCl stress (100 mM) decreased IAA content in leaves (32.57%), stem (22.01%) and roots (19.65%) of the control okra seedlings. However, an increase in IAA contents in leaves (143.04%), stem (115.32%), and roots (60.28%) were observed in okra plants inoculated with isolate CM1. By investigating the chemical profile of A. oryzae CM1 crude extract, we found sinapiic acid, 3,4-dimethyl-caffeic-acid, feruloylquinic-acid, coniferylaldehyde hexoside, cycloolivil, glucaric-acid, moracenin, kuwanon, sinapyl aldehyde, sophocarpine, propoxyphene and myricetin. Thus, NaCl stress causes an adverse effect on okra, however, the colonization of endophytic A. oryzae improves NaCl tolerance by ameliorating the physio-biochemical attributes and phytohormones production in host plant species. [ABSTRACT FROM AUTHOR]