Synthesis Of Sugars Research Articles

Application of brassinolide alleviates cold stress at the booting stage of rice

The objective of the study was to determine the physiological mechanisms of plants in response to brassinolide (BR) alleviating cold water stress on rice. In this study, physiological responses of rice to exogenous BR and cold water submergence were investigated using the chilling-tolerant cultivar Kongyu 131 (KY131) and the chilling-sensitive cultivar Kenjiandao 6 (KJD6). A total of 2 mg L−1 BR increased activities of superoxide dismutase (SOD) and peroxidase (POD) and the contents of soluble sugar, soluble protein, and chlorophyll, but decreased the malondialdehyde (MDA) content in KY131 and KJD6 under cold water stress. The observed decreases in SOD and POD activities and MDA content recovered quickly after plants were returned to irrigation with water at temperatures of about 23.0°C in 2014. Additionally, the contents of nitrogen (N), phosphorous (P), and potassium (K) were increased by BR treatment under cold water stress. Exposure to BR also raised the percentage of high effective leaf area and leaf area index at the heading stage. Furthermore, it promoted soluble sugar synthesis, increased the rate of dry matter accumulation, and enhanced the export and translocation rates of the stem-sheath. The yield in KJD6 was significantly (P≤0.01 and P≤0.05) higher than that of the control in 2013 and 2014, respectively. The effect of BR treatment on rice leaf SOD and POD activities, MDA, chlorophyll, P, and stem-sheath K contents were more significant in KJD6 than in KY131. In conclusion, exogenous BR effectively reduced the physiological and metabolic damage in rice due to cold stress at the booting stage, promoted functional recovery in plants that received irrigation with water at a normal temperature following cold stress, and mitigated the effects of cold water stress on yield. The two varieties exhibited differential responses to BR; the weaker cold-resistant variety was more sensitive to BR and displayed stronger responses to exogenous BR.

ITRAQ-based quantitative proteomic analysis of peach fruit (Prunus persica L.) at different ripening and postharvest storage stages

Abstract To better understand the global and dynamic changes in peach (Prunus persica L. cv. Xiahui 8) fruit protein expression, an efficient and reliable proteomic technique, iTRAQ, was used to investigate peach fruit proteome from day -7 to day 8 during storage period at 25 ± 1 °C. A total of 387 proteins with more than 1.2-fold abundance changes were observed. These differentially expressed proteins (DEPs) are mainly related to 17 functional categories. DEPs in day -7 were mainly responsible for sugar and carbohydrate syntheses, protein translation, expression and modification, and maintenance of osmotic balance in high ion and material transport capacities and strong redox reaction environment. Harvesting induced the increase of (small) heat shock protein. Upon harvest, the increased level of respiration rates on day 4 reached the highest level. polygalacturonase (PG), pectase lyase (PL), pectinesterase (PE), chorismate mutase (CM), peptidyl-prolyl isomerase (PPIase) and phytoene synthase (PSY) showed increased abundances and reached a peak at day 6, which significantly positive correlation with 9-cis-epoxycarotenoid dioxygenase (NCED) protein, accelerated fruit softening and metabolism of protein, amino acid and lipid. The emergence of eukaryotic translation initiation factor 5A (EIF5A) on day 8 signified the intensification of apoptosis. Our study facilitated a comprehensive understanding of the complex proteomic reprograming and ripening-associated mechanisms that could be used for endeavors of breeding and postharvest processing to improve peach fruit quality.

Chemical Synthesis and Immunological Evaluation of a Pentasaccharide Bearing Multiple Rare Sugars as a Potential Anti-pertussis Vaccine.

With the infection rate of Bordetella pertussis at a 60-year high, there is an urgent need for new anti-pertussis vaccines. The lipopolysaccharide (LPS) of B. pertussis is an attractive antigen for vaccine development. With the presence of multiple rare sugars and unusual glycosyl linkages, the B. pertussis LPS is a highly challenging synthetic target. In this work, aided by molecular dynamics simulation and modeling, a pertussis-LPS-like pentasaccharide was chemically synthesized for the first time. The pentasaccharide was conjugated with a powerful carrier, bacteriophage Qβ, as a vaccine candidate. Immunization of mice with the conjugate induced robust anti-glycan IgG responses with IgG titers reaching several million enzyme-linked immunosorbent assay (ELISA) units. The antibodies generated were long lasting and boostable and could recognize multiple clinical strains of B. pertussis, highlighting the potential of Qβ-glycan as a new anti-pertussis vaccine.

Chemical Synthesis and Immunological Evaluation of a Pentasaccharide Bearing Multiple Rare Sugars as a Potential Anti‐pertussis Vaccine

AbstractWith the infection rate of Bordetella pertussis at a 60‐year high, there is an urgent need for new anti‐pertussis vaccines. The lipopolysaccharide (LPS) of B. pertussis is an attractive antigen for vaccine development. With the presence of multiple rare sugars and unusual glycosyl linkages, the B. pertussis LPS is a highly challenging synthetic target. In this work, aided by molecular dynamics simulation and modeling, a pertussis‐LPS‐like pentasaccharide was chemically synthesized for the first time. The pentasaccharide was conjugated with a powerful carrier, bacteriophage Qβ, as a vaccine candidate. Immunization of mice with the conjugate induced robust anti‐glycan IgG responses with IgG titers reaching several million enzyme‐linked immunosorbent assay (ELISA) units. The antibodies generated were long lasting and boostable and could recognize multiple clinical strains of B. pertussis, highlighting the potential of Qβ‐glycan as a new anti‐pertussis vaccine.

Interferon tau: Influences on growth and development of the conceptus

Interferon tau (IFNT), the pregnancy recognition signal secreted from trophectoderm cells of ruminant conceptuses abrogates the uterine luteolytic mechanism to ensure maintenance of functional corpora lutea for production of progesterone (P4). Importantly, IFNT, in concert with P4, also induces expression of genes in uterine luminal (LE) and superficial glandular (sGE) epithelia for transport and/or secretion of histotroph into the uterine lumen to support growth and development of the conceptus. For example, IFNT and P4 induce transporters responsible foer transport of glucose and arginine into the uterine lumen during the peri-implantation period of pregnancy. Arginine activates the mechanistic target of rapamycin (MTOR) nutrient sensing cell signaling pathway to stimulate proliferation, migration, differentiation and translation of mRNAs essential for growth and development of the conceptus. Glucose not utilized by the conceptus is converted to fructose and those two hexose sugars are metabolized via aerobic glycolysis to produce metabolites used in the hexosamine biosynthesis pathway, pathways for one-carbon metabolism, and pentose phosphate pathway for synthesis of ribose sugars and NADPH. Arginine is metabolized to nitric oxide (NO) that stimulates angiogenesis in uterine and placental tissues, and to polyamines required for many cellular functions critical for growth and development of the conceptus. In summary, IFNT and P4 regulate expression of genes for transport of select nutrients into the pregnant uterus during the peri-implantation period of pregnancy. Those nutrients are then metabolized via multiple metabolic pathways to not only provide ATP, but also substrates for synthesis of nucleotides, amino acids, co-factors required for growth, development, and survival of conceptuses during the peri-implantation period of pregnancy.

Biochemical changes in response to canopy position of avocado fruit (cv. ‘Carmen’ and ‘Hass’) during growth and development and relationship with maturity

In the current study, biochemical changes of avocado fruit cv. ‘Carmen’ and ‘Hass’ were evaluated during growth, development and maturation. The aim was to determine if exposure of fruit to sunlight could vary the biochemical compounds associated with maturity, and hence be among the causes of uneven maturity, and ripening. The current study also seeks to evaluate if the mesocarp C7 sugars, oil and DM content have a relationship with fruit maturity. The study was conducted in a commercial orchard at Everdon Estates in the KwaZulu-Natal, South Africa. Nine avocado fruit (cv. ‘Carmen’ and ‘Hass’ avocado) per canopy were sampled bi-weekly for assessment of mesocarp dry matter (DM), oil content, D-mannoheptulose, perseitol and total C7 sugars. The significantly (p < 0.001) higher DM and oil content in fruit that were sampled from the outside canopy in both cultivars suggested an early maturity, and vice versa inside canopy. The higher D-mannoheptulose and perseitol in fruit sampled inside canopy as a storage reserve was associated with the rate of respiration, which is slower inside canopy due to cooler temperatures. This results in accumulation of higher overall C7 sugars that are slowly used up as a substrates of respiration for synthesis of overall DM, oils, proteins, C6 sugars and other biochemical constituents associated with ripening. In terms of maturity, higher D-mannoheptulose and perseitol implies that fruit from the inside canopy will take longer to mature and to reach edible ripeness when harvested. This then causes uneven maturity of fruit, only characterized by uneven ripening.

Multi-Step Exploitation of Raw Arundo donax L. for the Selective Synthesis of Second-Generation Sugars by Chemical and Biological Route

Lignocellulosic biomass represents one of the most important feedstocks for future biorefineries, being a precursor of valuable bio-products, obtainable through both chemical and biological conversion routes. Lignocellulosic biomass has a complex matrix, which requires the careful development of multi-step approaches for its complete exploitation to value-added compounds. Based on this perspective, the present work focuses on the valorization of hemicellulose and cellulose fractionsof giant reed (Arundo donax L.) to give second-generation sugars, minimizing the formation of reaction by-products. The conversion of hemicellulose to xylose was undertaken in the presence of the heterogeneous acid catalyst Amberlyst-70 under microwave irradiation. The effect of the main reaction parameters, such as temperature, reaction time, catalyst, and biomass loadings on sugars yield was studied, developing a high gravity approach. Under the optimised reaction conditions (17 wt% Arundo donax L. loading, 160 °C, Amberlyst-70/Arundo donax L. weight ratio 0.2 wt/wt), the xylose yield was 96.3 mol%. In the second step, the cellulose-rich solid residue was exploited through the chemical or enzymatic route, obtaining glucose yields of 32.5 and 56.2 mol%, respectively. This work proves the efficiency of this innovative combination of chemical and biological catalytic approaches, for the selective conversion of hemicellulose and cellulose fractions of Arundo donax L. to versatile platform products.

Identification of differentially expressed photosynthesis- and sugar synthesis-related genes in tomato (Solanum lycopersicum) plants grown under different CO2 concentrations

The aim of the present study was to identify key genes and molecular biological processes that are responsive to CO2 enrichment in tomato (Solanum lycopersicum L.). Tomato plants were exposed to CO2 concentrations of either 350–500 μmol/mol (ambient) or 750–850 μmol/mol, and genes that were differentially expressed (DEGs) in the two groups were identified. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were then used to identify DEGs involved in photosynthesis and sugar synthesis. As a result, a total of 208 DEGs, including 179 up-regulated and 29 down-regulated genes, were identified. GO functional annotation revealed that the DEGs were mainly enriched in the processes of photosystem I, photosystem II, photosynthesis phosphate ion binding, and electron carrier activity, whereas the KEGG pathway analysis indicated that the DEGs were mainly enriched in 21 signalling pathways, including plant hormone signal transduction, RNA polymerase, ribosomes and photosynthesis. A total of 62 DEGs, including Solyc12g032970.1, Solyc12g032960.1, Solyc07g043480.1 and Solyc02g086650.2, were associated with photosynthesis and sugar synthesis. The present study provides a basis for investigating the effects of elevated CO2 on the molecular processes of tomato, which will, in turn, provide a theoretical basis for tomato breeding programs.

Synthesis, characterization and thermokinetic analysis of the novel sugar based styrene co-polymer

Abstract A new α-chloralose (1,2-O-(R)-trichloroethylidene-α-D-glucofuranose)-based copolymer of styrene (PSVTEG) (2) was synthesized from vinyl (hydroxyl) furan monomer (1) and styrene by a conventional free radical polymerization reaction. The thermal decomposition kinetics of polymer were investigated by means of thermogravimetric analysis in dynamic nitrogen atmosphere at different heating rates. The apparent activation energy for the main stage thermal decomposition of the copolymer PSVTEG (2) was calculated using the Flynn-Wall-Ozawa and found to be 159.0±3 kj/mol. In addition, the activation energy value was calculated according to Coats-Redfern method and found to be compatible with the obtained result. The thermogram of the glycopolymer (PSVTEG) (2) has two decomposition stages and the calculated activation energy indicated that the main degradation stage is a nonspontaneous process (integral form 1/(1−α)2 for F3).

Enzymatic Synthesis of Glycans and Glycoconjugates.

Glycoconjugates have great potential to improve human health in a multitude of different ways and fields. Prominent examples are human milk oligosaccharides and glycosaminoglycans. The typical choice for the production of homogeneous glycoconjugates is enzymatic synthesis. Through the availability of expression and purification protocols, recombinant Leloir glycosyltransferases are widely applied as catalysts for the synthesis of a wide range of glycoconjugates. Extensive utilization of these enzymes also depends on the availability of activated sugars as building blocks. Multi-enzyme cascades have proven a versatile technique to synthesize and in situ regenerate nucleotide sugar.In this chapter, the functions and mechanisms of Leloir glycosyltransferases are revisited, and the advantage of prokaryotic sources and production systems is discussed. Moreover, in vivo and in vitro pathways for the synthesis of nucleotide sugar are reviewed. In the second part, recent and prominent examples of the application of Leloir glycosyltransferase are given, i.e., the synthesis of glycosaminoglycans, glycoconjugate vaccines, and human milk oligosaccharides as well as the re-glycosylation of biopharmaceuticals, and the status of automated glycan assembly is revisited.

Structure and function relationships of sugar oxidases and their potential use in biocatalysis.

Several sugar oxidases that catalyze the oxidation of sugars have been isolated and characterized. These enzymes can be classified as flavoenzyme due to the presence of flavin adenine dinucleotide (FAD) as a cofactor. Sugar oxidases have been proposed to be the key biocatalyst in biotransformation of carbohydrates which can potentially convert sugars to provide a pool of intermediates for synthesis of rare sugars, fine chemicals and drugs. Moreover, sugar oxidases have been applied in biosensing of various biomolecules in food industries, diagnosis of diseases and environmental pollutant detection. This review provides the discussions on general properties, current mechanistic understanding, structural determination, biocatalytic application, and biosensor integration of representative sugar oxidase enzymes, namely pyranose 2-oxidase (P2O), glucose oxidase (GO), hexose oxidase (HO), and oligosaccharide oxidase. The information regarding the relationship between structure and function of these sugar oxidases points out the key properties of this particular group of enzymes that can be modified by engineering, which had resulted in a remarkable economic importance.

Vinyl sulfone-modified carbohydrates: Michael acceptors and 2π partners for the synthesis of functionalized sugars and enantiomerically pure carbocycles and heterocycles.

Increasing demands for molecules with skeletal complexity, including those of stereochemical diversity, require new synthetic strategies. Carbohydrates have been used extensively as chiral building blocks for the synthesis of various complex molecules. On the other hand, the vinyl sulfone group has been identified as a unique functional group, which acts either as a Michael acceptor or a 2π partner in cycloaddition reactions. A combination of the high reactivity of the vinyl sulfone group and the in-built chiralities of carbohydrates has the potential to function as a powerful tool to generate a wide variety of enantiomerically pure reactive intermediates. Since CS bond formation in carbohydrates is easily achieved with regioselectivity, further synthetic manipulations of these thiosugars has led to the generation of a wide range of vinyl sulfone-modified furanosyl, pyranosyl, acyclic, and bicyclic carbohydrates. Several approaches have been studied to standardize the preparative methods for accessing vinyl sulfone-modified carbohydrates at least on a gram scale. Reactions of these modified carbohydrates with appropriate reagents afford a large number of new chemical entities primarily via (i) Michael addition reactions, (ii) desulfostannylation, (iii) Michael-initiated ring-closure reactions, and (iv) cycloaddition reactions. A wide range of desulfonylating reagents in the context of sensitive molecules such as carbohydrates have also been extensively studied. Applications of these strategies have led to the synthesis of (a) amino sugars and branched-chain sugars, (b) C-glycosides, (c) enantiomerically pure cyclopropanes, five- and six-membered carbocycles, (d) saturated oxa-, aza-, and thio-monocyclic heterocycles, (e) bi-and tricyclic saturated oxa and aza heterocycles, (f) enantiomerically pure and trisubstituted pyrroles, (g) 1,5-disubstituted 1,2,3-triazolylated carbohydrates and the corresponding triazole-linked di- and trisaccharides, (h) divinyl sulfone-modified carbohydrates and densely functionalized S,S-dioxothiomorpholines, and (i) modified nucleosides. Details of reaction conditions were incorporated as much as possible and mechanistic discussions were included wherever necessary.

Synthesis and characterization of a novel sugar based cross-linker

There are very few literature reports on the synthesis of monosaccharide based cross-linkers. A novel monosaccharide sugar-based cross-linker was synthesized by using D-mannitol, and allyl chloride in basic medium at low temperature (40°C) under inert atmospheric conditions. We have used a new synthetic scheme which does not involve the use of autoclave at high temperature and pressure for carrying out allylation with allyl chloride. The synthesized product has been characterized by, Fourier-transform infrared (FT-IR) spectra and 1 H Nuclear magnetic resonance (1 HNMR) spectra. The formation of allyl mannitol was also confirmed with the help of elemental analysis of C, H and O. Cross linked polymer gel samples were prepared by polymerizing acrylic acid monomer alongwith the synthesized cross-linker at different concentrations. Aqueous gels have been prepared from the cross-linked polymers and their swelling capacity has been studied. It has been found that these gels act as superabsorbent materials. The optimum ratio of cross-linker and acrylic acid monomer for the preparation of gel having highest swelling capacity (~ 28000% of water) was found to be 0.03 g crosslinker with 12.0 g. monomer.

Synthesis of novel sugar based xanthates for the removal of copper and nickel harmful heavy metals from water

Synthesis of novel sugar based xanthates for the removal of copper and nickel harmful heavy metals from water

Synthesis of novel sugar based xanthates for the removal of copper and nickel harmful heavy metals from water

Synthesis of novel sugar based xanthates for the removal of copper and nickel harmful heavy metals from water

Total Synthesis of the Lipid-Anchor-Attached Core Trisaccharides of Lipoteichoic Acids of Streptococcus pneumoniae and Streptococcus oralis Uo5.

Herein we report an efficient total synthesis of lipid-anchor-appended core trisaccharides of lipoteichoic acids of Streptococcus pneumoniae and Streptococcus oralis Uo5. The key features include the expedient synthesis of the rare sugar 2,4,6-trideoxy-2-acetamido-4-amino-d-Galp building block via one-pot sequential SN2 reactions and the α-selective coupling of d-thioglucoside with the diacyl glycerol acceptor to construct a common disaccharide acceptor, which was utilized in the total synthesis of target molecules 1 and 2.

Identification and Validation of Differentially Expressing Transcripts from Top and Bottom Internodes of High-Sucrose Sugarcane Variety CoJ64

Sugarcane is one of the most important cash crops worldwide, with ability to store high sucrose in its stalk. Due to complex and polyploid genome, improvement in sucrose content in sugarcane through routine genetical and molecular implements is limited. In the era of the next-generation sequencing, transcriptomic studies targeted to different tissues at defined crop stage would play decisive role in identifying distinct transcripts/genes regulating various agronomical traits including sucrose content in sugarcane culm. In the present pursuit, transcriptomes of bottom and top internodes of a high sugar variety (CoJ64) were analyzed to define/validate the differentially expressing transcripts associated with sugar metabolism. Of 173,821 transcripts, 116,777 transcripts differentially expressing in these two sets of tissues were further functionally annotated. Six hundred and eight transcripts were fished out on the basis of their significant read count difference. Ten selected transcripts belonging to sugar synthesis and transportation, cellular signaling, stress responsive genes and transcription factor were validated through real-time PCR, and the results indicated differential expression during stages of sugar accumulation. A specific water stress-related myb transcription factor identified depicted gradual increase in its expression with cane maturity, possibly helping cane to withstand water deficit during ripening stage of the cane for high sucrose accumulation. Beside these some hypothetical and uncharacterized transcripts were also recognized having high expression at immature stage of the crop, presumably enhancing sink strength for high sugar accumulation in this variety supported with the various domains observed in their predicted secondary structure.

Transcriptome profiling using RNA-seq to provide insights into foxtail millet seedling tolerance to short-term water deficit stress induced by PEG-6000

Foxtail millet (Setaria italica L.) with high drought resistance, is grown widely in arid and semi-arid regions of the world, and it is a new model plant for genetic and molecular studies. To uncover the molecular mechanisms of stress-tolerance in different genotypes of foxtail millet, physiological analyses combined with transcriptional profiling were conducted using a time-course analysis on two foxtail millet genotypes Damaomao (DM) and Hongnian (HN). The genotype DM performed better than HN under water deficiency, with more moderate relative water content (RWC) and chlorophyll decline. Further physiological and RNA-seq investigations revealed that the two genotypes possessed high conservatism in some vital biological pathways which respond to drought stress, involving hormone synthesis, proline, and soluble sugar synthesis, and reactive oxygen species (ROS) metabolism. However, some genes related to these pathways showed different expression profiles. Likewise, the lower malondialdehyde (MDA) content in HN than DM may be explained by the observation that HN contained more activated genes in the ascorbate-glutathione cycle using KEGG pathway analysis. Overall, abscisic acid (ABA) response genes, ROS scavengers which were probably involved in signaling responses, a set of enzymes involved in proline and soluble sugar synthesis, channel protein genes, and transcription factors, encompassed the early strategy of foxtail millet response to drought. These findings provide a comprehensive molecular view of how different foxtail millet genotypes respond to short-term osmotic stress.

Hypoxic Non-replicating Persistent Mycobacterium tuberculosis Develops Thickened Outer Layer That Helps in Restricting Rifampicin Entry.

Bacteria undergo adaptive morphological changes to survive under stress conditions. The present work documents the morphological changes in Mycobacterium tuberculosis (Mtb) cells cultured under hypoxic condition using Wayne’s in vitro hypoxia model involving non-replicating persistence stages 1 and 2 (NRP stage 1 and NRP stage 2) and reveals their physiological significance. Transmission electron microscopy of the NRP stage 2 cells showed uneven but thick outer layer (TOL), unlike the evenly thin outer layer of the actively growing mid-log phase (MLP) cells. On the contrary, the saprophytic Mycobacterium smegmatis NRP stage 2 cells lacked TOL. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) of the Mtb NRP stage 2 cells confirmed the rough uneven surface unlike the smooth surface of the MLP cells. Zeta potential measurements showed high negative charge on the surface of NRP stage 2 cells and polysaccharide specific calcofluor white (CFW) staining of the cells revealed high content of polysaccharide in the TOL. This observation was supported by the real-time PCR data showing high levels of expression of the genes involved in the synthesis of sugars, such as trehalose, mannose and others, which are implicated in polysaccharide synthesis. Experiments to understand the physiological significance of the TOL revealed restricted entry of the biologically low-active 5-carboxyfluorescein-rifampicin (5-FAM-RIF), at concentrations equivalent to microbicidal concentrations of the unconjugated biologically active rifampicin, into the NRP stage 2 cells, unlike in the MLP cells. Further, as expected, mechanical removal of the TOL by mild bead beating or release of the NRP stage 2 cells from hypoxia into normoxia in fresh growth medium also significantly increased 5-FAM-RIF permeability into the NRP stage 2 cells to an extent comparable to that into the MLP cells. Taken together, these observations revealed that Mtb cells under hypoxia develop TOL that helps in restricting rifampicin entry, thereby conferring rifampicin tolerance.

Calcium availability regulates antioxidant system, physio-biochemical activities and alleviates salinity stress mediated oxidative damage in soybean seedlings

Salinity is considered as one of the devastating abiotic stress factors and global climate change has further worsened the situation. Present experiments were aimed to evaluate the role of calcium (Ca) availability on growth and salinity tolerance mechanisms in soybean. Seedlings were grown with (2 mM Ca) and without Ca supplementation and modulation in key physiological and biochemical parameters were studied. Salinity (100 mM NaCl) stress resulted in growth reduction in terms of height and biomass accumulation, which was more pronounced in Ca-deficient plants. Relative to control (Ca deficient) and NaCl stressed plants, Ca supplemented seedlings exhibited higher relative water content, pigment synthesis and the photosynthetic efficiency. Ca availability affected the synthesis of proline, glycine betaine and soluble sugars under normal and saline growth conditions. Optimal Ca supplementation up-regulated the activities of antioxidant enzymes assayed and the contents of non-enzymatic antioxidants (ascorbate, glutathione, and tocopherol) thereby reflecting in amelioration of NaCl induced oxidative damage. Moreover, increased accumulation of phenols due to Ca supplementation and the amelioration of NaCl mediated decline if nitrate reductase activity was observed. More importantly, Ca availability reduced the accumulation of Na under control and NaCl stressed conditions restricting the damging effects on metabolism. Availability of optimal Ca potentially regulates the salinity tolerance mechanisms in soybean by maintaining osmoregulation and antioxidant metabolism.