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Today, understanding of cell wall evolution is incomplete due to limited knowledge of cell wall structure of non-flowering plants. Besides polysaccharides, proteoglycans like arabinogalactan-proteins are important constituents of the cell wall of most if not all seed plants. This article provides the first detailed characterization of AGPs from a lycophyte and different ferns, which are the closest living relatives to seed plants. The amount of protein in fern AGPs (6–12%) was in a range comparable to most seed plant AGPs. However, it was higher for Lycopodium AGP (17%). The carbohydrate moieties of investigated AGPs showed typical features known for type-II arabinogalactans from seed plants and showed cross-reaction with polyclonal antibodies raised against Echinacea AGP. On the other hand, unusual structural components like high quantities of pyranosidic arabinose residues for Lycopodium AGP and 3- O -methyl-rhamnose for fern AGPs have been detected. [ABSTRACT FROM AUTHOR]

Abstract: This investigation shows structural features of two macromolecules from roots of Echinacea pallida (Nutt.) Nutt: an arabinogalactan-protein (AGP) and an arabinan. The arabinogalactan-protein was precipitated with β-glucosyl Yariv reagent from a high molecular weight fraction. Investigations of the neutral sugar composition revealed Gal (52.1% w/w) and Ara (38.2% w/w) in a ratio of 1.4:1, accompanied by Glc (6.9% w/w) and Rha (2.8% w/w). The content of uronic acids was 6.2%. Mild acid hydrolysis detects Ara and Glc being located at the periphery of the molecule. Linkage analyses and NMR spectroscopy revealed a backbone of the polysaccharide mainly consisting of 3-linked and 3,6-linked Galp-residues. Side chains are composed of 3,6-linked or 6-linked Galp terminating in 5-linked Araf, terminal Araf, Glcp and GlcAp. The protein part (3.9% w/w) of the AGP is rich in Hyp, Ser, Ala, Thr, Glu, Asp and Gly. The amount of Hyp was determined by a colorimetric method and found to be (0.65% (w/w) of the AGP, which is in good agreement with the result obtained by amino acid hydrolysis (0.67% w/w). The arabinan was isolated from the supernatant of the Yariv precipitation on the basis of solubility in EtOH (80%). It mainly consists of Ara (85.8%). Linkage analyses and NMR spectroscopy indicate a highly branched molecule, consisting of 3,5-linked, 5-linked and terminal Araf-residues in equal amounts. [Copyright &y& Elsevier]

Abstract: Mucilage is thought to play a role in salinity tolerance in certain halophytic species by regulating water ascent and ion transport. The localization and composition of mucilage in the halophyte Kosteletzkya virginica was therefore investigated. Plants were grown in a hydroponic system in the presence or absence of 100mM NaCl and regularly harvested for growth parameter assessment and mucilage analysis with the gas liquid chromatography method. NaCl treatment stimulated shoot growth and biomass accumulation, had little effect on shoot and root water content, and reduced leaf water potential (Ψ w), osmotic potential (Ψ s) as well as stomatal conductance (g s). Mucilage increased in shoot, stems and roots in response to salt stress. Furthermore, changes were also observed in neutral monosaccharide components. Levels of rhamnose and uronic acid increased with salinity. Staining with a 0.5% alcian blue solution revealed the presence of mucopolyssacharides in xylem vessels and salt-induced mucilaginous precipitates on the leaf abaxial surface. Determination of ion concentrations showed that a significant increase of Na+ and a decrease of K+ and Ca2+ simultaneously occurred in tissues and in mucilage under salt stress. Considering the high proportion of rhamnose and uronic acid in stem mucilage, we suggest that the pectic polysaccharide could be involved in Na+ fixation, though only a minor fraction of accumulated sodium appeared to be firmly bound to mucilage. [Copyright &y& Elsevier]

• AGPs from gymnosperms Ginkgo, Cycas, Ephedra and Encephalartos were characterized. • The unusual monosaccharide acofriose was found in AGPs from Ginkgo, Ephedra and Encephalartos. • A unique attribute of Ginkgo AGP is a glycan part mixed of type I and II AGs. • Bioinformatic investigations on glycosyltransferases complete analytical results. • The study contributes to understanding of evolution of AGPs during life on land. Arabinogalactan-proteins (AGPs), important signalling molecules of the plant cell wall, are structurally extensively investigated in angiosperms, but information on AGPs in gymnosperms is still limited. We characterized AGPs from the gymnosperms Ginkgo biloba , Ephedra distachya , Encephalartos longifolius and Cycas revoluta. The protein contents are comparable to that of angiosperm AGPs. Hydroxyproline is the site of linking the carbohydrate part and was detected in all AGPs with highest concentration in Cycas AGP (1.1 % of the AGP). Interestingly, with the exception of Cycas , all AGPs contained the monosaccharide 3- O -methylrhamnose not present in angiosperm polysaccharides. The carbohydrate moieties of Cycas and Ephredra showed the main components 1,3,6-linked galactose and terminal arabinose typical of angiosperm AGPs, whereas that of Ginkgo AGP was unique with 1,4-linked galactose as dominant structural element. Bioinformatic search for glycosyltransferases in Ginkgo genome also revealed a lower number of galactosyltransferases responsible for biosynthesis of the 1,3-Gal/1,6-Gal AGP backbone. [ABSTRACT FROM AUTHOR]

Arabinogalactan-proteins (AGPs) are important proteoglycans of plant cell walls. They seem to be present in most, if not all seed plants, but their occurrence and structure in bryophytes is widely unknown and actually the focus of AGP research. With regard to evolution of plant cell wall, we isolated AGPs from the three mosses Sphagnum sp., Physcomitrella patens and Polytrichastrum formosum . The moss AGPs show structural characteristics common for AGPs of seed plants, but also unique features, especially 3- O -methyl-rhamnose (trivial name acofriose) as terminal monosaccharide not found in arabinogalactan-proteins of angiosperms and 1,2,3-linked galactose as branching point never found in arabinogalactan-proteins before. [ABSTRACT FROM AUTHOR]

Root extracts of the medicinal plant Pelargonium sidoides , native to South Africa, are used globally for the treatment of common cold and cough. Due to an increasing economic commercialization of P. sidoides remedies, wild collections of root material should be accompanied by effective methods for plant propagation like somatic embryogenesis. Based on this, the influence of arabinogalactan-proteins (AGPs) on somatic embryogenesis and plant propagation of P. sidoides has been investigated. High-molecular weight AGPs have been isolated from dried roots as well as from cell cultures of P. sidoides with yields between 0.1% and 0.9%, respectively. AGPs are characterized by a 1,3-linked Gal p backbone, branched at C6 to 1,6-linked Gal p side chains terminated by Ara f and to a minor extent by Glc p A, Gal p or Rha p . Treatment of explants of P. sidoides with AGPs from roots or suspension culture over 5.5 weeks resulted in effective stimulation of somatic embryo development and plant regeneration. [ABSTRACT FROM AUTHOR]

Abstract: An arabinogalactan from wood of the larch tree (Larix laricina), which is a source of dietary fiber, is composed of d-galactose and l-arabinose in a 6:1 molar ratio accompanied by small amounts of d-glucuronic acid. The molecular mass has been determined to be 38kDa. Linkage analysis in combination with partial hydrolysis and spectroscopic investigations revealed a 1,3-linked Galp backbone, branched at C6 to 1,6-linked Galp side residues terminated by Galp, Arap, Araf or GlcpA. Monoclonal antibodies directed against a type-II-arabinogalactan from Echinacea purpurea showed cross reactivity with the larch arabinogalactan and have been used to develop an ELISA for quantification of this polysaccharide. [Copyright &y& Elsevier]

This study intends to investigate the inhibitory potential of different plant derived saccharides on cell migration and adhesion of pancreatic ductal adenocarcinoma (PDAC) cells to microvascular liver endothelium, particularly considering the role of transmembranous galectin-3. PDAC cell lines PancTu1 and Panc1 were characterized by considerable (transmembranous) galectin-3 (Gal3) expression. SiRNA mediated Gal3 knockdown as well as treatment with differentially processed pectins and arabinogalactan-proteins (AGPs) did not impact on cell migration of either PDAC cell line. In contrast, Gal3 knockdown reduced adhesion of PDAC cells to the liver endothelial cell line TMNK-1 being more pronounced in Panc1 cells. Similarly, plant derived substances did not impact cell adhesion of PancTu1 cells while partially hydrolyzed citrus pectin (MCP), pectinase-treated MCP (MCP Pec) and partially hydrolized AGP (AGP TFA) clearly diminished adhesive properties of Panc1 cells. MCP Pec or AGP TFA could not further intensify the adhesion reducing effect of galectin-3 knockdown, indicating that these plant derived polysaccharides are able to inhibit PDAC cell adhesion to liver endothelial cells in a galectin-3 dependent manner. Overall, these data suggest an inhibitory potential of plant derived processed saccharides which have undergone chemical modification in impairing PDAC cell adhesion to liver endothelium. Image 1 • An in vitro testsystem for adhesion of pancreatic ductal adenocarcinoma (PDAC) to liver cells has been developed. • The role of transmembranous galectin-3 on this process is in the focus of this work. • SiRNA mediated Gal3 knockdown reduced adhesion of PDAC cells to the liver cell line TMNK-1. • Modified plant galactans clearly diminished adhesive properties of PDAC cells. • Overall, these data suggest an inhibitory potential of plant derived processed galactans on metastasis. [ABSTRACT FROM AUTHOR]