Search Results (10)

The organisation of hemicelluloses within the pollen intine of many monocots remains inadequately characterised, partly due to the masking of epitopes within complex wall matrices. In this study, mature pollen grains of Gagea lutea (L.) Ker-Gawl. were analysed using immunofluorescence and immunogold technique with a variety of monoclonal antibodies that target xyloglucan (LM15, LM24, LM25, CCRC-M48), heteroxylan (LM10, LM11), heteromannan (LM21, LM22), and xylan (CCRC-M138). Semithin sections of LR White were examined both untreated and following a sequential enzymatic pretreatment, which included alkaline de-esterification followed by treatment with pectate lyase (RbPel1A) and endo-β-mannanase 5A. In untreated pollen, xyloglucan-related epitopes were identified within the intine, accompanied by additional intracellular labelling for LM15, and LM25; while for LM24 signal was only to the intine ring. Conversely, CCRC-M48 exhibited a more punctate distribution. Neither xylan- nor mannan-related epitopes were detected in the wall or intracellularly. The enzymatic digestion significantly altered the detectability of epitopes, resulting in an increase in continuous wall labelling within the intine across multiple probes. These findings indicate that enzymatic modification of pectic and mannan components has a considerable impact on the apparent distribution of hemicellulose epitopes within the pollen wall of G. lutea. Together, these results expand the still limited in situ immunolocalisation evidence base for hemicellulose-related epitopes in pollen, and provide a practical framework for interpreting digestion-dependent changes primarily in terms of epitope accessibility within the intine matrix. Full article

Carnivorous plants have fascinated botanists and ecologists with their various unusual adaptations in organ structure, physiology, and complex interactions with other organisms since the time of Charles Darwin. Species of the genus Utricularia (bladderworts, family Lentibulariaceae) are carnivorous plants that prey mainly on invertebrates using traps (bladders) of leaf origin. In the traps, there are glandular trichomes called quadrifids, which produce digestive enzymes and absorb the products of prey digestion. These quadrifids are unique due to their highly complex glandular cell structure; hence, they are an excellent model for studying the cell wall and its specialization. The main aim of the study was to investigate the presence and distribution of homogalacturonans (HGs) and hemicelluloses in the cell walls of trichome cells and especially in cell wall ingrowths in the quadrifid cells. The following antibodies were used against the wall components: anti-HGs (homogalacturonans) —JIM5 (low methylesterified HGs), JIM7 (highly esterified HGs), LM19 (low methylesterified HGs), CCRC-M38 (a fully de-esterified HG), LM5 (galactan); anti-hemicelluloses—LM25 (galactoxyloglucan; XXLLG, XXLG, XXXG modules of xyloglucans), LM15 (xyloglucan), CCRC-M138 (xylan), LM11 (heteroxylan); and anti-mannans: LM20 (heteromannan) and LM22 (heteromannan). The localization of the examined compounds was determined using immunohistochemistry techniques and immunogold labeling. In quadrifid cells, we found differences in the presence of the epitope detected by the LM5 antibody in the cell walls. In addition, cell wall ingrowths represented distinct microdomains of the cell wall in terms of the occurrence of wall components (they were methylesterified and demethylesterified homogalacturonan-poor). Hemicelluloses (galactoxyloglucan and xyloglucan) and arabinogalactans co-occur in cell wall ingrowths. Also, a part of the cell wall of the pedestal cell, which forms a Casparian strip, represented a distinct microdomain. We did not detect epitopes recognized by LM11, LM20 and LM22 antibodies. Our research shows that several cell wall microdomains occur in the cell walls of quadrifid cells. They differ depending on the presence and distribution of low methylesterified HGs, highly esterified HGs, fully de-esterified HGs, galactan (the epitope detected by the LM5 antibody), xyloglucan, galactoxyloglucan, and xylan (the epitope detected by the CCRC-M138 antibody). Full article

Celery (Apium graveolens) can be considered as a model plant for studying pectin-enriched primary cell walls. In addition to parenchyma cells with xyloglucan-deficient walls, celery petioles contain collenchyma, a mechanical tissue with thickened cell walls of similar composition. This study presents a comprehensive analysis of these tissues at both early and late developmental stages, integrating data on polysaccharide yield, composition, localization, and transcriptome analysis. Our results reveal that young collenchyma walls possess distinct polysaccharide compositions, including higher levels of rhamnogalacturonan I (RG-I), branched galactans, esterified homogalacturonan, and xyloglucan, compared to parenchyma cells. A significant number of genes encoding proteins involved in pectin methylesterification and acetylation were upregulated in young collenchyma. Different gene isoforms encoding glycosyltransferases involved in RG-I biosynthesis were activated in both collenchyma and parenchyma, suggesting potential variations in RG-I structure and function across different primary cell walls. We identified a set of potential glycosyltransferases involved in RG-I biosynthesis in collenchyma and proposed synthase complexes for heteromannan and heteroxylan. The transcriptome data not only confirmed known biochemical traits of celery cell walls but also provided deeper insights into the peculiarities of cell wall polysaccharide metabolism, thereby helping to narrow down candidate genes for further molecular genetic studies. Full article

In the present study, a heteromannan primarily composed of mannose, fucose, xylose, glucose, and arabinose at a molar ratio of 4.78:1.18:1:0.82:0.11 containing a low proportion of glucuronic acid with weight-average molecular weights of 3.6 × 10⁶ Da, named NTP, was prepared from the fruiting body of Tremella fuciformis. The anti-skin-aging effects of NTP on d-Galactose-induced aging mice and the biological mechanisms were investigated by an iTRAQ-based proteomics approach. NTP substantially mitigated skin aging characterized by a decreased loss of hydroxyproline and hyaluronic acid and reduced oxidative stress in the skin. Moreover, 43 differentially expressed proteins (DEPs) were identified in response to NTP, of which 23 were up-regulated and 20 were down-regulated. Bioinformatics analysis revealed that these DEPs were mainly involved in the biological functions of cellular and metabolic regulations, immune system responses, and structural components. The findings provided new insights into the biological mechanisms underlying the anti-skin-aging actions of T. fuciformis-derived polysaccharides and facilitated NTP applications in naturally functional foods. Full article

Plant cell wall biosynthesis is a complex process that requires proteins and enzymes from glycan synthesis to wall assembly. We show that disruption of At3g50120 (DUF247-1), a member of the DUF247 multigene family containing 28 genes in Arabidopsis, results in alterations to the structure and composition of cell wall polysaccharides and reduced growth and plant size. An ELISA using cell wall antibodies shows that the mutants also exhibit ~50% reductions in xyloglucan (XyG), glucuronoxylan (GX) and heteromannan (HM) epitopes in the NaOH fraction and ~50% increases in homogalacturonan (HG) epitopes in the CDTA fraction. Furthermore, the polymer sizes of XyGs and GXs are reduced with concomitant increases in short-chain polymers, while those of HGs and mHGs are slightly increased. Complementation using 35S:DUF247-1 partially recovers the XyG and HG content, but not those of GX and HM, suggesting that DUF247-1 is more closely associated with XyGs and HGs. DUF247-1 is expressed throughout Arabidopsis, particularly in vascular and developing tissues, and its disruption affects the expression of other gene members, indicating a regulatory control role within the gene family. Our results demonstrate that DUF247-1 is required for normal cell wall composition and structure and Arabidopsis growth. Full article

The study aimed to investigate exopolysaccharides (EPSs) produced by two Antarctic yeasts isolated from Livingston Island. The species were identified as Vishniacozyma victoriae (V) and Tremellomycetes sp. (T) based on a molecular genetic analysis of ITS1-5.8S-ITS4 regions of the 18S rRNA gene. The EPS production was investigated under stress conditions in culture flasks and a bioreactor. Different chromatographic (HPLC-RID, HPSEC-RID) and spectral (FT-IR) analyses were employed to characterize EPSs. Tremellomycetes sp. accumulated 7 g/L biomass and 4.5 g/L EPS after 120 h of cultivation. The total carbohydrate content of V-EPS and T-EPS was 75.4% and 79.0%, respectively. The EPSs mainly consisted of mannose (30–32%), which was followed by glucose, xylose, galactose, and small amounts of uronic acids (6.3–7.0%). EPSs had appreciable amounts of proteins (11–12%). The FT-IR spectra contained absorption bands typical for hetero-mannans and β-glucans (797–1033 cm⁻¹). EPSs were heterogeneous with a broad molecular weight distribution range (47 × 10⁴–68 × 10⁴ g/mol). In conclusion, both yeasts synthesized high-molecular-weight heteromannans, and Tremellomycetes sp. stood out as being a better producer than V. victoriae. The current study also formed a basis for a better assessment of the potential for practical application of EPSs and yeasts in biochemical engineering and biotechnology. Full article

Root border cells (BCs) and their associated secretions form a protective structure termed the root extracellular trap (RET) that plays a major role in root interactions with soil borne microorganisms. In this study, we investigated the release and morphology of BCs of Glycine max using light and cryo-scanning electron microscopy (SEM). We also examined the occurrence of cell-wall glycomolecules in BCs and secreted mucilage using immunofluorescence microscopy in conjunction with anti-glycan antibodies. Our data show that root tips released three populations of BCs defined as spherical, intermediate and elongated cells. The mechanism of shedding seemed to be cell morphotype-specific. The data also show that mucilage contained pectin, cellulose, extracellular DNA, histones and two hemicellulosic polysaccharides, xyloglucan and heteromannan. The latter has never been reported previously in any plant root secretions. Both hemicellulosic polysaccharides formed a dense fibrillary network embedding BCs and holding them together within the mucilage. Finally, we investigated the effect of the RET on the interactions of root with the pathogenic oomycete Phytophthora parasitica early during infection. Our findings reveal that the RET prevented zoospores from colonizing root tips by blocking their entry into root tissues and inducing their lysis. Full article

Passiflora foetida is a horticultural plant and vital traditional Chinese herbal medicine. In our previous study, the characterization and immuno-enhancing effect of fruits polysaccharide 1 (PFP1), a water-eluted hetero-mannan from wild Passiflora foetida fruits, were investigated. Herein, another three salt-eluted novel polysaccharides, namely PFP2, PFP3, and PFP4, were obtained and structurally characterized. The results showed that PFP2, PFP3, and PFP4 were three structurally similar hetero-galacturonans with different molecular weights of 6.11 × 10⁴, 4.37 × 10⁴_, and 3.48 × 10⁵ g/mol, respectively. All three of these hetero-galacturonans are mainly composed of galacturonic acid, galactose, arabinose (75.69%, 80.39%, and 74.30%, respectively), and other monosaccharides including mannose, fucose, glucose, ribose, xylose, and glucuronic acid (24.31%, 19.61, and 25.70%, respectively), although differences in their backbone structure exist. Additionally, immunomodulatory assay indicated that the three hetero-galacturonans possess the ability to promote the production of nitric oxide (NO), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) in RAW264.7 macrophages in a concentration-dependent manner (p < 0.05). Especially, PFP3 displayed a stronger enhancing effect than PFP2 and PFP4 at the minimum effective concentration. Therefore, the results suggested that the obtained three salt-eluted hetero-galacturonans, especially PFP3, could be utilized as immunomodulatory effectivity ingredients in nutritional/pharmaceutical industries. Full article

Plant cells are surrounded by an extracellular matrix that consists mainly of polysaccharides. Many molecular components involved in plant cell wall polymer synthesis have been identified, but it remains largely unknown how these molecular players function together to define the length and decoration pattern of a polysaccharide. Synthetic biology can be applied to answer questions beyond individual glycosyltransferases by reconstructing entire biosynthetic machineries required to produce a complete wall polysaccharide. Recently, this approach was successful in establishing the production of heteromannan from several plant species in an orthogonal host—a yeast—illuminating the role of an auxiliary protein in the biosynthetic process. In this review we evaluate to what extent a selection of organisms from three kingdoms of life (Bacteria, Fungi and Animalia) might be suitable for the synthesis of plant cell wall polysaccharides. By identifying their key attributes for glycoengineering as well as analyzing the glycosidic linkages of their native polymers, we present a valuable comparison of their key advantages and limitations for the production of different classes of plant polysaccharides. Full article

For more than a decade, the Arabidopsis seed coat epidermis (SCE) has been used as a model system to study the synthesis, secretion and modification of cell wall polysaccharides, particularly pectin. Our detailed re-evaluation of available biochemical data highlights that Arabidopsis seed mucilage is more than just pectin. Typical secondary wall polymers such as xylans and heteromannans are also present in mucilage. Despite their low abundance, these components appear to play essential roles in controlling mucilage properties, and should be further investigated. We also provide a comprehensive community resource by re-assessing the mucilage phenotypes of almost 20 mutants using the same conditions. We conduct an in-depth functional evaluation of all the SCE genes described in the literature and propose a revised model for mucilage production. Further investigation of SCE cells will improve our understanding of plant cell walls. Full article