Cell-wall Polysaccharides of Potatoes
25
Citation
109
Reference
10
Related Paper
Citation Trend
Keywords:
Pectin
Xyloglucan
The primary plant cell wall is composed of the polysaccharide classes pectin, hemicellulose and cellulose, and together, all these polysaccharides form a complex network. However, it is still poorly understood how these polysaccharides together build up the complex primary plant cell wall network. This research aimed at a further understanding of the architecture of the plant cell wall, predominantly focussing on pectin and its potential interactions with (hemi)cellulose. To overcome the insoluble nature of hemicellulose, cellulose and part of all pectin in muro, methods for targeted disruption of the cell wall were developed. The residue after sequential alkali-water extractions still contained 31% of all pectin in carrot. Half of this pectin was released by glucanase digestion of the alkali residue, and was proposed to be present in a covalently linked pectin-cellulose complex. The proposed pectin-cellulose complex was not found in tomato and strawberry, making this a unique characteristic of the carrot cell wall. Planetary ball milling was introduced as a suitable tool to enhance extraction yields with limited depolymerisation of cell wall polysaccharides, allowing a more representative characterisation of cell wall polysaccharides including alkali-labile substituents. Milling followed by water extraction increased the extractability to 75% of all initially insoluble uronic acid and 60% of all initially insoluble xylose. It was proposed that a covalently linked pectin-xylan complex was released from the tomato cell wall, containing 18% of solubilised uronic acid, next to 48% of all xylose. For the sources studied in this research, the proposed pectin-xylan complex was a unique feature of the tomato cell wall. Alternatively, planetary ball milling followed by LiCl-DMSO extraction also solubilised cellulose, next to an increased extractability of pectin and hemicellulose. Whereas LiCl-DMSO solubilised pectin with a low HG:RG-I ratio, the HG:RG-I ratio for the subsequent buffer extractions increased by a factor 2-7. Characterisation of both LiCl-DMSO soluble and insoluble fractions showed methyl-esterified and highly acetylated pectin, showing the potential of characterising methyl-esterification and acetylation of both soluble and insoluble pectin by using LiCl-DMSO. For both carrot and strawberry, pectin homogalacturonan regions were found to be highly acetylated. For carrot, also the additional part of water soluble pectin solubilised by heat processing contained highly methyl-esterified, acetylated HG regions. More firmly associated pectin populations were relatively higher in RG-I, for all different extraction procedures used. This was observed for pectin extracted after heat processing, sequential water-alkaline extractions and milling followed by water or LiCl-DMSO extraction. Finally, the distribution of pectin over different pectin domains was discussed, and compared between sources.
Pectin
Hemicellulose
Uronic acid
Residue (chemistry)
Cite
Citations (3)
Xyloglucan
Pectin
Cellulosic ethanol
Cite
Citations (131)
Xyloglucan
Pectin
Degree of polymerization
Cite
Citations (18)
To understand the architecture of the plant cell wall, it is of importance to understand both structural characteristics of cell wall polysaccharides and interactions between these polysaccharides. Interactions between polysaccharides were studied in the residue after water and chelating agent extraction by sequential extractions with H2O and alkali. The 6 M alkali residue still represented 31%, 11% and 5% of all GalA present in carrot, tomato and strawberry, respectively, and these pectin populations were assumed to strongly interact with cellulose. Digestion of the carrot 6 M alkali residue by glucanases released ∼27% of the 6 M residue, mainly representing pectin. In tomato and strawberry alkali residues, glucanases were not able to release pectin populations. The ability of glucanases to release pectin populations suggests that the carrot cell wall contains unique, covalent interactions between pectin and cellulose.
Pectin
Residue (chemistry)
Cite
Citations (207)
The matrix polysaccharides of plant cell walls are diverse and variable sets of polymers influencing cell wall, tissue and organ properties. Focusing on the relatively simple parenchyma tissues of four fruits - tomato, aubergine, strawberry and apple - we have dissected cell wall matrix polysaccharide contents using sequential solubilisation and antibody-based approaches with a focus on pectic homogalacturonan (HG) and rhamnogalacturonan-I (RG-I). Epitope detection in association with anion-exchange chromatography analysis indicates that in all cases solubilized polymers include spectra of HG molecules with unesterified regions that are separable from methylesterified HG domains. In highly soluble fractions, RG-I domains exist in both HG-associated and non-HG-associated forms. Soluble xyloglucan and pectin-associated xyloglucan components were detected in all fruits. Aubergine glycans contain abundant heteroxylan epitopes, some of which are associated with both pectin and xyloglucan. These profiles of polysaccharide heterogeneity provide a basis for future studies of more complex cell and tissue systems.
Pectin
Parenchyma
Cite
Citations (59)
Resurrection plants have the unique capacity to revive from an air-dried state. In order to tolerate desiccation they have to overcome a number of stresses, mechanical stress being one. In leaves of the Craterostigma species, an extensive shrinkage occurs during drying as well as a considerable cell wall folding. Our previous microscopically analysis using immunocytochemistry on the resurrection plant Craterostigma wilmsii, has shown an increase in labelling of xyloglucan and unesterified pectins in the cell wall during drying. In this study, we have undertaken a biochemical approach to separate, quantify and characterize major cell wall polysaccharides in fully hydrated and dry leaves of C. wilmsii. Our results show that the overall cell wall composition of C. wilmsii leaves was similar to that of other dicotyledonous plants with respect to the pectin content. However, the structure of the hemicellulosic polysaccharide xyloglucan was characterized to be XXGG-type. The data also demonstrate marked changes in the hemicellulosic wall fraction from dry plants compared to hydrated ones. The most conspicuous change was a decrease in glucose content in the hemicellulosic fraction of dry plants. In addition, xyloglucan from the cell wall of dry leaves was relatively more substituted with galactose than in hydrated walls. Together these findings show that dehydration induces significant alteration of polysaccharide content and structure in the cell wall of C. wilmsii, which in turn might be involved in the modulation of the mechanical properties of the wall during dehydration.
Xyloglucan
Pectin
Secondary cell wall
Cite
Citations (103)
Arabinogalactan
Xyloglucan
Pectin
Galactan
Cite
Citations (35)
Processing of fresh produce exposes cut surfaces of plant cell walls that then become vulnerable to human foodborne pathogen attachment and contamination, particularly by Salmonella enterica. Plant cell walls are mainly composed of the polysaccharides cellulose, pectin and hemicelluloses (predominantly xyloglucan). Our previous work used bacterial cellulose-based plant cell wall models to study the interaction between Salmonella and the various plant cell wall components. We demonstrated that Salmonella attachment was favoured in the presence of pectin while xyloglucan had no effect on its attachment. Xyloglucan significantly increased the attachment of Salmonella cells to the plant cell wall model only when it was in association with pectin. In this study, we investigate whether the plant cell wall polysaccharides mediate Salmonella attachment to the bacterial cellulose-based plant cell wall models through specific carbohydrate interactions or through the effects of carbohydrates on the physical characteristics of the attachment surface.We found that none of the monosaccharides that make up the plant cell wall polysaccharides specifically inhibit Salmonella attachment to the bacterial cellulose-based plant cell wall models. Confocal laser scanning microscopy showed that Salmonella cells can penetrate and attach within the tightly arranged bacterial cellulose network. Analysis of images obtained from atomic force microscopy revealed that the bacterial cellulose-pectin-xyloglucan composite with 0.3 % (w/v) xyloglucan, previously shown to have the highest number of Salmonella cells attached to it, had significantly thicker cellulose fibrils compared to other composites. Scanning electron microscopy images also showed that the bacterial cellulose and bacterial cellulose-xyloglucan composites were more porous when compared to the other composites containing pectin.Our study found that the attachment of Salmonella cells to cut plant cell walls was not mediated by specific carbohydrate interactions. This suggests that the attachment of Salmonella strains to the plant cell wall models were more dependent on the structural characteristics of the attachment surface. Pectin reduces the porosity and space between cellulose fibrils, which then forms a matrix that is able to retain Salmonella cells within the bacterial cellulose network. When present with pectin, xyloglucan provides a greater surface for Salmonella cells to attach through the thickening of cellulose fibrils.
Xyloglucan
Pectin
Bacterial Cellulose
Salmonella enterica
Plant cell
Cite
Citations (9)
SUMMARY Distinct polysaccharide fractions can be obtained from onion cell walls by sequential extraction methods. Pectins and xyloglucan molecules from these fractions have been imaged by electron microscopy and their lengths measured. Unexpectedly, instead of a simple distribution of lengths, both classes of matrix polysaccharide showed clear evidence of length periodicity, suggesting block polymer construction using subunits about 30 nm long, each containing a minimum of about sixty backbone sugar residues. These results are discussed in the light of our observation that the average hemicellulose cross‐link between cellulose microfibrils in the wall is also about 30 nm long, and that pectin forms a co‐extensive network with the cellulose/xyloglucan network. Using monoclonal antibodies to pectin we have further shown that even within a thin primary cell wall, containing only a few lamellae, distinct zones of pectin distribution are detectable, thus reinforcing our notion of the importance of domains in wall architecture. The chemical heterogeneity detected amongst pectins indicates that in a primary cell wall each lamella of cellulose microfibrils may be in a unique matrix environment.
Xyloglucan
Pectin
Middle lamella
Matrix (chemical analysis)
Hemicellulose
Secondary cell wall
Cite
Citations (102)
Xyloglucan
Pectin
Bacterial Cellulose
Microfibril
Hemicellulose
Cite
Citations (50)