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The halophyte plant species Kosteletzkya pentacarpos produces high amounts of mucilage which may play a role in heavy metal tolerance. The amount and composition of mucilage in K. pentacarpos exposed to zinc toxicity in the presence or in the absence of 50 mM NaCl was investigated. Exposure to 0.1 mM Zn had a detrimental impact on plants growth and water content. Most of Zn was accumulated in the roots of plants exposed to Zn toxicity both in the absence and in the presence of NaCl. Salinity, however, partially alleviated the toxicity of zinc, increasing the plant biomass and decreasing zinc absorption by the root. Crude mucilage content increased in all plant organs in response to Zn stress. Acid hydrolysis of crude mucilage extract revealed that the main neutral monosaccharide constituents were rhamnose, arabinose, galactose, and glucose. Zinc induced a rise in uronic acids in roots and stems but not in the leaves where a high constitutive proportion of uronic acids was observed. Meanwhile, changes were also observed in neutral monosaccharides component in different plant organs. Zinc stress increased the hemicellulose content, but decreased the lignin and cellulose content in the stem. Salinity slightly increased the cellulose content. We suggest that excessive zinc induces a modification in the composition and structure of polysaccharides and that mucilage may contribute to Zn tolerance through toxic ion sequestration. Article Highlights: Kosteletzkya pentacarpos is a halophyte plant species producing high amounts of mucilage. Salinity improved the resistance of this species to Zn excess. Zinc increased hemicellulose content as well as rhamnose and uronic acid in root and stem mucilage. Mucilage contributes to Zn tolerance through toxic ion sequestration [ABSTRACT FROM AUTHOR]

Seagrasses evolved from monocotyledonous land plants that returned to the marine habitat. This transition was accomplished by substantial changes in cell wall composition, revealing habitat-driven adaption to the new environment. Whether arabinogalactan-proteins (AGPs), important signalling molecules of land plants, are present in seagrass cell walls is of evolutionary and plant development interest. AGPs of Zostera marina L. were isolated and structurally characterised by analytical and bioinformatics methods as well as by ELISA with different anti-AGP antibodies. Calcium-binding capacity of AGPs was studied by isothermal titration calorimetry (ITC) and microscopy. Bioinformatic searches of the Z. marina proteome identified 9 classical AGPs and a large number of chimeric AGPs. The glycan structures exhibit unique features, including a high degree of branching and an unusually high content of terminating 4-O-methyl-glucuronic acid (4-OMe GlcA) residues. Although the common backbone structure of land plant AGPs is conserved in Z. marina, the terminating residues are distinct with high amounts of uronic acids. These differences likely result from the glycan-active enzymes (glycosyltransferases and methyltransferases) and are essential for calcium-binding properties. The role of this polyanionic surface is discussed with regard to adaption to the marine environment. [ABSTRACT FROM AUTHOR]

To explore the feasability of larch ( Larix decidua Mill.) embryogenic cell culture as alternative plant expression system, protein stability in fresh and conditioned medium was characterized in this study and compared to tobacco BY2 suspension culture. Fresh and conditioned media were spiked with 1 μg human IgG and IgG content was determined by ELISA after 24 h incubation. In fresh media, IgG recovery rate decreased to 12–23%. Adsorption on vessel walls probably is the best explanation for this IgG loss and EDTA in the medium strongly influenced wall adsorption. A high IgG recovery rate occurred in all conditioned cell culture media (7 or 14 days after inoculation). Changes in the low molecular weight-constitution of conditioned medium, rather than co-secreted polymers, are responsible for IgG stability in the cell suspension cultures. [ABSTRACT FROM AUTHOR]

A high molecular weight arabinogalactan protein (AGP) from the pressed juice of Echinacea purpurea, known to exhibit immunomodulatory properties in vitro, was characterized. Alkaline hydrolysis was carried out, leading to degradation of the protein core and to carbohydrate moieties linked to the amino acid responsible for binding. Gel permeation chromatography of these AG subunits gave one peak with a molecular weight of 30 × 103 Da. Hydroxyproline (42.9% w/w) was detected as the dominant amino acid after alkaline hydrolysis and was thus identified as the major amino acid responsible for the binding between the protein and the AG subunits via an O-glycosidic linkage. Large amounts of glutamine/glutamic acid (24.5% w/w) and asparagine/aspartic acid (17.3% w/w) were also found. Polyclonal antibodies raised against the intact AGP were shown to bind to the AG subunits too, indicating that the epitopes responsible for such interactions are localized in the polysaccharide moiety of the AGP. [ABSTRACT FROM AUTHOR]