Structure and Biological Roles of Sinorhizobium fredii HH103 Exopolysaccharide

Here we report that the structure of the Sinorhizobium fredii HH103 exopolysaccharide (EPS) is composed of glucose, galactose, glucuronic acid, pyruvic acid, in the ratios 5∶2∶2∶1 and is partially acetylated. A S. fredii HH103 exoA mutant (SVQ530), unable to produce EPS, not only forms nitrogen fixing nodules with soybean but also shows increased competitive capacity for nodule occupancy. Mutant SVQ530 is, however, less competitive to nodulate Vigna unguiculata. Biofilm formation was reduced in mutant SVQ530 but increased in an EPS overproducing mutant. Mutant SVQ530 was impaired in surface motility and showed higher osmosensitivity compared to its wild type strain in media containing 50 mM NaCl or 5% (w/v) sucrose. Neither S. fredii HH103 nor 41 other S. fredii strains were recognized by soybean lectin (SBL). S. fredii HH103 mutants affected in exopolysaccharides (EPS), lipopolysaccharides (LPS), cyclic glucans (CG) or capsular polysaccharides (KPS) were not significantly impaired in their soybean-root attachment capacity, suggesting that these surface polysaccharides might not be relevant in early attachment to soybean roots. These results also indicate that the molecular mechanisms involved in S. fredii attachment to soybean roots might be different to those operating in Bradyrhizobium japonicum.     

Composition of the Capsular and Extracellular Polysaccharides of Rhizobium japonicum: CHANGES WITH CULTURE AGE AND CORRELATIONS WITH BINDING OF SOYBEAN SEED LECTIN TO THE BACTERIA

The chemical compositions of the capsular and extracellular polysaccharides of two strains of Rhizobium japonicum (311b 138 and 110) have been determined and correlated as a function of culture age with the ability of the bacteria from which they were obtained to bind soybean seed lectin.     

Symbiotic properties and first analyses of the genomic sequence of the fast growing model strain Sinorhizobium fredii HH103 nodulating soybean

Glycine max (soybean) plants can be nodulated by fast-growing rhizobial strains of the genus Sinorhizobium as well as by slow-growing strains clustered in the genus Bradyrhizobium. Fast-growing rhizobia strains with different soybean cultivar specificities have been isolated from Chinese soils and from other geographical regions. Most of these strains have been clustered into the species Sinorhizobium fredii. The S. fredii strain HH103 was isolated from soils of Hubei province, Central China and was first described in 1985. This strain is capable to nodulate American and Asiatic soybean cultivars and many other different legumes and is so far the best studied fast-growing soybean-nodulating strain. Additionally to the chromosome S. fredii HH103 carries five indigenous plasmids. The largest plasmid (pSfrHH103e) harbours genes for the production of diverse surface polysaccharides, such as exopolysaccharides (EPS), lipopolysaccharides (LPS), and capsular polysaccharides (KPS). The second largest plasmid (pSfrHH103d) is a typical symbiotic plasmid (pSym), carrying nodulation and nitrogen fixation genes. The present mini review focuses on symbiotic properties of S. fredii HH103, in particular on nodulation and surface polysaccharides aspects. The model strain S. fredii HH103 was chosen for genomic sequencing, which is currently in progress. First analyses of the draft genome sequence revealed an extensive synteny between the chromosomes of S. fredii HH103 and Rhizobium sp. NGR234.     

Effects of Hexametaphosphate on Soybean Pectic Polysaccharide Extraction

The effects of sodium hexametaphosphate concentration, incubation temperature, and pH on the extraction of polysaccharide from soybean okara (soybean curd waste) were examined. The results suggest that the soybean polysaccharides were almost completely extracted with 50 times their volume of a 2% hexametaphosphate solution at 100°C for 2h, avoiding protein contamination. The viscosity, molecular weight, and sugar composition of the polysaccharides were compared with those of the commercially available samples. No differences were observed in the molecular weight or neutral sugar composition. However, it was found that the galacturonate distribution in the molecules of the two polysaccharides was different. The viscosity of the polysaccharide solution was changed by adding small amount of salt.     

Production of Capsular Polysaccharide of Streptococcus pneumoniae Type 14 and Its Purification by Affinity Chromatography

We describe a rapid and efficient method for producing the capsular polysaccharide of Streptococcus pneumoniae by fermentation on tryptic soy broth and purification of this compound by using immobilized soybean lectin as an affinity adsorbent. In principle, the same strategy can be used to produce purified capsular polysaccharides from other streptococcal serotypes by selecting the appropriate lectin adsorbents.     

Temporal relationships between the generalist predator,Orius insidiosus,and its two major prey in soybean

The generalist predator, Orius insidiosus (Say) is an important early-season predator of the soybean aphid, Aphis glycines Matsumura, a newly invasive pest of major concern in soybean crop management. We conducted a 3 year, multiple field study to characterize the dynamic relationships between the predator, the pest, and alternative prey in soybean. Using field sampling data, we showed that thrips were the only alternative prey to be well-established in fields prior to O. insidiosus arrival and were likely to promote predator colonization of soybean fields prior to the arrival of soybean aphid. The predator displayed a reproductive numerical response to thrips in one of the 3 years and a primarily aggregative response in another year. The predator did not respond numerically to soybean aphid in the majority of fields. Experimental manipulations of thrips populations in field plots temporarily reduced thrips densities but had a minimal effect on O. insidiosus densities, suggesting that the predator is resilient against temporary reductions in a major resource. In the 2 years O. insidiosus populations were well-established in fields prior to soybean aphid arrival, soybean aphid remained at low levels throughout the season. In the year soybean aphid arrived early with respect to the growing season and before O. insidiosus populations were established, soybean aphid reached outbreak levels in all fields. Future research efforts on the factors determining soybean aphid population dynamics need to address the relative importance of early-season soybean aphid colonization and generalist predator population dynamics on the potential for soybean aphid population outbreaks.     

Extraction and purification of pectic polysaccharides from soybean okara and enzymatic analysis of their structures

Pectic polysaccharides (6.74 g) were extracted from soybean okara (soybean curd waste, 30 g) with sodium hexametaphosphate solution. The extract was separated by DEAE-cellulose chromatography into galacturonate poor and galacturonate rich fractions. The fractionated polysaccharides were exhaustively degraded by three kinds of pectinase and two kinds of hemicellulase, namely exo- and endopolygalacturonases, exopolygalacturonate lyase, exogalactanase and exoarabinase. The values of the degradation limit revealed that the soybean pectic polysaccharides comprise regions of galacturonan and rhamnogalacturonan carrying side chains composed mainly of homogeneous arabinan and galactan. The galacturonan regions were distributed at both the reducing and nonreducing ends of the polysaccharide.     

Study of theRhizobium japonicum-soybean symbiosis

Summary Capsular polysaccharides were isolated fromRhizobium japonicum (61A76NS) and conjugated to a fluorescent dye to determine if the specificity in theRhizobium japonicum-soybean symbiosis is expressed by a component (lectin) located on soybean roots which binds to the sugars of the bacterial capsules.The conjugated Fraction A capsular polysaccharides ofR. japonicum bound only to the root hair tips of soybean seedlings. The polysaccharide would not bind specifically to the roots of clover or alfalfa seedlings. Rhodamine conjugated polysaccharides ofR. japonicum could be inhibited from binding to soybean root hairs by the addition of N-acetylgalactosamine or galactose, effective hapten inhibitors of this type of binding. This is the first report of hapten-reversible binding of an isolated rhizobial component to soybean root hairs, the differentiated epidermal cells which are subsequently infected by this nitrogen-fixing symbiont.Paper number6046 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, North Carolina.     

Extraction, preliminary structural characterization, and antioxidant activities of polysaccharides from Salvia miltiorrhiza Bunge

Four polysaccharides were extracted from Salvia miltiorrhiza Bunge using hot water, ultrasonic, alkali, and enzyme methods. Preliminary structural characterization was conducted by physicochemical property, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) analyses. Antioxidant activities against 2,2-diphenyl-1-picryl-hydrazyl (DPPH), hydroxyl, and superoxide radicals were also evaluated. The physicochemical property analysis indicated the identicalness of the polysaccharide indices obtained by the hot water and ultrasonic methods. The indices obtained by the alkali and enzyme methods were significantly different. The FTIR spectra revealed the general characteristic absorption peaks of the four polysaccharides. The SEM images demonstrated significant differences in the surface features of the different polysaccharides. The antioxidant activity assay revealed the significant antioxidant activities of three polysaccharides. Overall, the polysaccharides from S. miltiorrhiza Bunge may have potential applications in the medical and food industries.     

Genomic,molecular evolution,and expression analysis of NOX genes in soybean (Glycine max)

Reactive oxygen species (ROS) are versatile signaling molecules in sensing stresses and play critical roles in signaling and development. Plasma membrane NADPH oxidases (NOXs) are key producers of ROS, and play important roles in the regulation of plant-pathogen interactions. Here, we performed a comprehensive analysis of the NOX gene family in the soybean genome (Glycine max) and 17 NOX (GmNOX) genes were identified. Structural analysis revealed that the GmNOX proteins in soybean were as conserved as those in other plants. 8 duplicated gene pairs were formed by a Glycine-specific whole-genome duplication (WGD) event approximately 13 million years ago (Mya). The Ka/Ks ratios of GmNOX genes ranged from 0.04 to 0.28, suggesting that the GmNOX family had undergone purifying selection in soybean. Gene expression patterns showed different expression of these duplicate genes, suggesting that the GmNOXs were retained by substantial subfunctionalization during the soybean evolutionary processes. Subsequently, the expression of GmNOXs in response to drought and phytohormones were characterized via qPCR. Importantly, four GmNOXs showed strong expression in nodules, pointing to their probable involvement in nodulation. Thus, our results shed light on the evolutionary history of this family in soybean and contribute to the functional characterization of GmNOX genes in soybean.     

The IQD Gene Family in Soybean: Structure,Phylogeny, Evolution and Expression

Members of the plant-specific IQ67-domain (IQD) protein family are involved in plant development and the basal defense response. Although systematic characterization of this family has been carried out in Arabidopsis, tomato (Solanum lycopersicum), Brachypodium distachyon and rice (Oryza sativa), systematic analysis and expression profiling of this gene family in soybean (Glycine max) have not previously been reported. In this study, we identified and structurally characterized IQD genes in the soybean genome. A complete set of 67 soybean IQD genes (GmIQD1–67) was identified using Blast search tools, and the genes were clustered into four subfamilies (IQD I–IV) based on phylogeny. These soybean IQD genes are distributed unevenly across all 20 chromosomes, with 30 segmental duplication events, suggesting that segmental duplication has played a major role in the expansion of the soybean IQD gene family. Analysis of the Ka/Ks ratios showed that the duplicated genes of the GmIQD family primarily underwent purifying selection. Microsynteny was detected in most pairs: genes in clade 1–3 might be present in genome regions that were inverted, expanded or contracted after the divergence; most gene pairs in clade 4 showed high conservation with little rearrangement among these gene-residing regions. Of the soybean IQD genes examined, six were most highly expressed in young leaves, six in flowers, one in roots and two in nodules. Our qRT-PCR analysis of 24 soybean IQD III genes confirmed that these genes are regulated by MeJA stress. Our findings present a comprehensive overview of the soybean IQD gene family and provide insights into the evolution of this family. In addition, this work lays a solid foundation for further experiments aimed at determining the biological functions of soybean IQD genes in growth and development.     

Anti-bacterial,anti-scavenging and cytotoxic activity of garden cress polysaccharides

Plants polysaccharides are an infinite stock of drug composites with varying pharmacological and biological activities. The present investigation aimed to examine the antibacterial, anti-scavenging and cytotoxic potential of garden cress (GC) polysaccharides. The antibacterial effects vs Escherichia coli and as well as Staphylococcus aureus of GC polysaccharides were examined by means of agar diffusion assay, minimum inhibitory concentration (MIC), outer and inner cell membrane permeability. Antioxidant potential of the GC polysaccharides were performed by free radical DPPH scavenging, superoxide anion scavenging, hydroxyl radical scavenging, reducing power potential assay, and hydrogen peroxide method. Cytotoxicity potential of GC polysaccharides were evaluated by MTT assay in human cervical (HeLa) and liver carcinoma (HepG2) cell lines. The findings showed that GC polysaccharides MIC were 1.06 and 0.56 mg mL⁻¹ against E. coli and S. aureus, respectively. Compared to the standard inhibitor, the GC polysaccharides showed essential inhibitor assays in a very dose dependent approach, and notable actions to scavenge reactive oxygen species (ROS) are also due to the large quantities of hydrophilic polyphenols. The IC₅₀ values of all tested parameters were measured against standard ascorbic acid antioxidant agent. The GC polysaccharides diminish the cell viability percentage of HeLa and HepG2 in a concentration dependent manner. GC polysaccharides at a dose of 500 µg ml⁻¹ exhibited higher anti-tumor activity in both HeLa (65.33 ± 3.75%) and HepG2 (60.33 ± 3.48%). The findings obtained in this study indicate that GC polysaccharides has antibacterial and has a possible source of natural antioxidant and also has cytotoxic effect on different carcinoma cell lines.     

Nodulation, Nitrogen Fixation, and Hydrogen Oxidation by Pigeon Pea Bradyrhizobium spp. in Symbiotic Association with Pigeon Pea, Cowpea, and Soybean

The pigeon pea strains of Bradyrhizobium CC-1, CC-8, UASGR(S), and F4 were evaluated for nodulation, effectiveness for N₂ fixation, and H₂ oxidation with homologous and nonhomologous host plants. Strain CC-1 nodulated Macroptilium atropurpureum, Vigna unguiculata, Glycine max, and G. soja but did not nodulate Pisum sativum, Phaseolus vulgaris, Trigonella foenum-graecum, and Trifolium repens. Strain F4 nodulated G. max cv. Peking and PI 434937 (Malayan), but the symbioses formed were poor. Similarly, G. max cv. Peking, cv. Bragg, PI 434937, PR 13-28-2-8-7, and HM-1 were nodulated by strain CC-1, and symbioses were also poor. G. max cv. Williams and cv. Clark were not nodulated. H₂ uptake activity was expressed with pigeon pea and cowpea, but not with soybean. G. max cv. Bragg grown in Bangalore, India, in local soil not previously exposed to Bradyrhizobium japonicum formed nodules with indigenous Bradyrhizobium spp. Six randomly chosen isolates, each originating from a different nodule, formed effective symbioses with pigeon pea host ICPL-407, nodulated PR 13-28-2-8-7 soybean forming moderately effective symbioses, and did not nodulate Williams soybean. These results indicate the six isolates to be pigeon pea strains although they originated from soybean nodules. Host-determined nodulation of soybean by pigeon pea Bradyrhizobium spp. may depend upon the ancestral backgrounds of the cultivars. The poor symbioses formed by the pigeon pea strains with soybean indicate that this crop should be inoculated with B. japonicum for its cultivation in soils containing only pigeon pea Bradyrhizobium spp.     

Exploring the potential of biopharmaceutical production by Rigidoporus ulmarius: Cultivation,chemistry, and bioactivity studies

Rigidoporus ulmarius is used as a medicinal fungus in Asia. Three isolates (denoted #61, #62, and #63) of R. ulmarius were collected, and their biological activities were evaluated. Extracted polysaccharides from isolate #63 showed greater inhibition activity compared to isolates #61 and #62 in an in vitro endothelial cell tube formation assay, a standard evaluation of angiogenesis. The polysaccharides and ethanolic extract of isolate #63 dose-dependently suppressed the production of the interferon (IFN)-γ-induced inflammation marker, IP-10. Chemical analyses of the polysaccharides revealed that isolate #63 contained the highest value of fucose at a concentration of 59.1 ± 1.2 μmol/g polysaccharide. These results suggest that fucose-containing polysaccharides may play a role in the inhibitory effect. Isolate #63 showed the highest values of ADP among the three isolates in the ethanolic extract. These results suggest that different isolates from R. ulmarius exhibit different abilities to regulate antiangiogenic and anti-inflammatory processes.     

Determination of the linkages in some methylated,sialic acid-containing,meningococcal polysaccharides by mass spectrometry

The application of gas-liquid chromatography-mass spectrometric (g.l.c.-m.s.) analysis to a number of sialic acid-containing polysaccharides of meningococcal origin has been studied. Methylation of these polysaccharides by the Hakomori conditions resulted in both O- and N-methylation. Methanolysis of the methylated polysaccharides from serogroup C [(2→9)-linked], colominic acid [(2→8)-linked], and serogroups Y and W-135 [both (1→4)-linked], yielded the respective 4,7,8,4,7,9-, and 7,8,9-tri-O-methyl derivatives of methyl N-acetyl-N-methyl-β-D-neuraminate methyl glycoside. As model compounds, methyl N-acetyl-4,7,8,9-tetra-O-methyl-α-D-neuraminate methyl glycoside and its N-methyl derivative were also synthesized. All of the methylated derivatives could be identified on the basis of their typical fragmentation-patterns, indicating that this method is applicable to the determination of the position of linkages to sialic acid residues in biopolymers.     

Analysis of the molecular construction of xylogalacturonan isolated from soluble soybean polysaccharides

Soluble soybean polysaccharides (SSPS) extracted from soybean cotyledons are acidic polysaccharides, and exhibited a pectin-like structure. After digesting galacturonan with polygalacturonase, two novel galacturonan (GN) fragments, which were directly linked to xylosyl oligosaccharides, were obtained. One consisted of (beta-D-Xyl)7 branched at the C-3 site of 1,4-linked (alpha-D-GalA)4, and the other consisted of (beta-D-Xyl)4 branched at the C-3 site of 1,4-linked (alpha-D-GalA)3.     

Evolutionary history of mitogen-activated protein kinase (MAPK) genes in Lotus,Medicago, and Phaseolus

Mitogen-Activated Protein Kinase (MAPK) genes encode proteins that mediate various signaling pathways associated with biotic and abiotic stress responses in eukaryotes. The MAPK genes form a 3-tier signal transduction cascade between cellular stimuli and physiological responses. Recent identification of soybean MAPKs and availability of genome sequences from other legume species allowed us to identify their MAPK genes. The main objectives of this study were to identify MAPKs in 3 legume species, Lotus japonicus, Medicago truncatula, and Phaseolus vulgaris, and to assess their phylogenetic relationships. We used approaches in comparative genomics for MAPK gene identification and named the newly identified genes following Arabidopsis MAPK nomenclature model. We identified 19, 18, and 15 MAPKs and 7, 4, and 9 MAPKKs in the genome of Lotus japonicus, Medicago truncatula, and Phaseolus vulgaris, respectively. Within clade placement of MAPKs and MAPKKs in the 3 legume species were consistent with those in soybean and Arabidopsis. Among 5 clades of MAPKs, 4 founder clades were consistent to MAPKs of other plant species and orthologs of MAPK genes in the fifth clade-"Clade E" were consistent with those in soybean. Our results also indicated that some gene duplication events might have occurred prior to eudicot-monocot divergence. Highly diversified MAPKs in soybean relative to those in 3 other legume species are attributable to the polyploidization events in soybean. The identification of the MAPK genes in the legume species is important for the legume crop improvement; and evolutionary relationships and functional divergence of these gene members provide insights into plant genome evolution.     

A Comparative Study of the Physiology of Symbioses Formed by Rhizobium japonicum with Glycine max, Vigna unguiculata, and Macroptilium atropurpurem

Although Rhizobium japonicum nodulates Vigna unguiculata and Macroptilium atropurpurem, little is known about the physiology of these symbioses. In this study, strains of R. japonicum of varying effectiveness on soybean were examined. The nonhomologous hosts were nodulated by all the strains tested, but effectiveness was not related to that of the homologous host. On siratro, compared to soybean, many strains reversed their relative effectiveness ranking. Both siratro and cowpea produced more dry matter with standard cowpea rhizobia CB756 and 176A22 than with the strains of R. japonicum. Strains USDA33 and USDA74 were more effective with siratro and cowpea than with soybean. The strain USDA122 expressed high rates of hydrogenase activity in symbiosis with the cowpea as well as the soybean host. The strains USDA61 and USDA74 expressed low levels of hydrogenase activity in symbiosis with cowpea, but no activity was found with soybean. Our results indicate host influence for the expression of hydrogenase activity, and suggest the possibility of host influence of nitrogenase for the allocation of electrons to N₂ and H⁺.     

Natural products with hypoglycemic, hypotensive, hypocholesterolemic, antiatherosclerotic and antithrombotic activities

This article reviews compounds of botanical origin which are capable of lowering plasma levels of glucose and cholesterol and blood pressure, as well as compounds inhibiting atherosclerosis and thrombosis. Hypoglycemic natural products comprise flavonoids, xanthones, triterpenoids, alkaloids, glycosides, alkyldisulfides, aminobutyric acid derivatives, guanidine, polysaccharides and peptides. Hypotensive compounds include flavonoids, diterpenes, alkaloids, glycosides, polysaccharides and proteins. Among natural products with hypocholesterolemic activity are beta-carotene, lycopene, cycloartenol, beta-sitosterol, sitostanol, saponin, soybean protein, indoles, dietary fiber, propionate, mevinolin (beta-hydroxy-beta-methylglutaryl coenzyme A reductase inhibitor) and polysaccharides. Heparins, flavonoids, tocotrienols, beta-hydroxy-beta-methylglutaryl coenzyme A reductase inhibitors (statins), garlic compounds and fungal proteases exert antithrombotic action. Statins and garlic compounds also possess antiatherosclerotic activity.