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Current challenges in cell wall biology in the cereals and grasses.

Burton RA, Fincher GB - Front Plant Sci (2012)

Bottom Line: Firstly, in the area of human health it is now recognized that cell wall polysaccharides are key components of dietary fiber, which carries significant health benefits.Certain grasses and cereals walls also contain (1,3;1,4)-β-glucans, which are not widely distributed outside the Poaceae.Here we review current knowledge of cell wall biology in plants and highlight emerging technologies that are providing new and exciting insights into the most challenging questions related to the synthesis, re-modeling and degradation of wall polysaccharides.

View Article: PubMed Central - PubMed

Affiliation: Australian Research Council Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, SA, Australia.

ABSTRACT
Plant cell walls consist predominantly of polysaccharides and lignin. There has been a surge of research activity in plant cell wall biology in recent years, in two key areas. Firstly, in the area of human health it is now recognized that cell wall polysaccharides are key components of dietary fiber, which carries significant health benefits. Secondly, plant cell walls are major constituents of lignocellulosic residues that are being developed as renewable sources of liquid transport biofuels. In both areas, the cell walls of the Poaceae, which include the cereals and grasses, are particularly important. The non-cellulosic wall polysaccharides of the Poaceae differ in comparison with those of other vascular plants, insofar as they contain relatively high levels of heteroxylans as "core" polysaccharide constituents and relatively smaller amounts of heteromannans, pectic polysaccharides, and xyloglucans. Certain grasses and cereals walls also contain (1,3;1,4)-β-glucans, which are not widely distributed outside the Poaceae. Although some genes involved in cellulose, heteroxylan, and (1,3;1,4)-β-glucan synthesis have been identified, mechanisms that control expression of the genes are not well defined. Here we review current knowledge of cell wall biology in plants and highlight emerging technologies that are providing new and exciting insights into the most challenging questions related to the synthesis, re-modeling and degradation of wall polysaccharides.

No MeSH data available.


Diagrammatical representation of structural features found in heteroxylans of the grasses. Details of the linkage types involved in the polysaccharides are outlined in the text. Figure prepared by Dr Hunter Laidlaw.
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Figure 1: Diagrammatical representation of structural features found in heteroxylans of the grasses. Details of the linkage types involved in the polysaccharides are outlined in the text. Figure prepared by Dr Hunter Laidlaw.

Mentions: The heteroxylans of the grasses consist of a (1,4)-linked backbone of β-D-xylopyranosyl (Xylp) residues, to which is appended single α-L-arabinofuranosyl (Araf), single α-D-glucuronopyranosyl (GlcpA) residues, or the 4-O-methyl ethers of GlcpA residues (Izydorczyk and Biliaderis, 1994; Fincher and Stone, 2004). In some cases oligosaccharide substituents such as β-D-Xylp-(1,2)-L-Araf-(1- and β-D-Galp(1,4)-β-D-Xylp-(1,2)-L-Araf-(1- are also detected in heteroxylans (Fincher and Stone, 2004). The Araf residues are usually linked to the C(O)3 position of the Xylp residues, but on occasions are found on C(O)2 or on both of these carbon atoms. The GlcpA residues are usually linked to the C(O)2 atom of the Xylp residues. The structural features of plant heteroxylans are summarized in Figure 1. The number and distribution of substituents along the (1,4)-β-xylan backbone vary between and within species, and are major determinants of the physicochemical properties of the heteroxylans (Ebringerová, 2005). In the heteroxylans from the starchy endosperm of grasses, the major substituents are Araf residues; GlcpA residues are less common. If the (1,4)-β-xylan backbone is heavily substituted with Araf residues, the polysaccharide will be more soluble, because the Araf residues sterically inhibit intermolecular alignment of individual molecules and prevent aggregation and precipitation. Physical alignment will also occur between arabinoxylans and cellulose, in regions where lengths of the (1,4)-β-xylan backbone are unsubstituted. The solubility of the arabinoxylan can be predicted from the Xyl:Ara ratio of the polysaccharide, at least in general terms. For example, less substituted, less soluble arabinoxylans are found in the pericarp–testa of cereal bran and in other secondary cell wall material (Fincher and Stone, 2004).


Current challenges in cell wall biology in the cereals and grasses.

Burton RA, Fincher GB - Front Plant Sci (2012)

Diagrammatical representation of structural features found in heteroxylans of the grasses. Details of the linkage types involved in the polysaccharides are outlined in the text. Figure prepared by Dr Hunter Laidlaw.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3375588&req=5

Figure 1: Diagrammatical representation of structural features found in heteroxylans of the grasses. Details of the linkage types involved in the polysaccharides are outlined in the text. Figure prepared by Dr Hunter Laidlaw.
Mentions: The heteroxylans of the grasses consist of a (1,4)-linked backbone of β-D-xylopyranosyl (Xylp) residues, to which is appended single α-L-arabinofuranosyl (Araf), single α-D-glucuronopyranosyl (GlcpA) residues, or the 4-O-methyl ethers of GlcpA residues (Izydorczyk and Biliaderis, 1994; Fincher and Stone, 2004). In some cases oligosaccharide substituents such as β-D-Xylp-(1,2)-L-Araf-(1- and β-D-Galp(1,4)-β-D-Xylp-(1,2)-L-Araf-(1- are also detected in heteroxylans (Fincher and Stone, 2004). The Araf residues are usually linked to the C(O)3 position of the Xylp residues, but on occasions are found on C(O)2 or on both of these carbon atoms. The GlcpA residues are usually linked to the C(O)2 atom of the Xylp residues. The structural features of plant heteroxylans are summarized in Figure 1. The number and distribution of substituents along the (1,4)-β-xylan backbone vary between and within species, and are major determinants of the physicochemical properties of the heteroxylans (Ebringerová, 2005). In the heteroxylans from the starchy endosperm of grasses, the major substituents are Araf residues; GlcpA residues are less common. If the (1,4)-β-xylan backbone is heavily substituted with Araf residues, the polysaccharide will be more soluble, because the Araf residues sterically inhibit intermolecular alignment of individual molecules and prevent aggregation and precipitation. Physical alignment will also occur between arabinoxylans and cellulose, in regions where lengths of the (1,4)-β-xylan backbone are unsubstituted. The solubility of the arabinoxylan can be predicted from the Xyl:Ara ratio of the polysaccharide, at least in general terms. For example, less substituted, less soluble arabinoxylans are found in the pericarp–testa of cereal bran and in other secondary cell wall material (Fincher and Stone, 2004).

Bottom Line: Firstly, in the area of human health it is now recognized that cell wall polysaccharides are key components of dietary fiber, which carries significant health benefits.Certain grasses and cereals walls also contain (1,3;1,4)-β-glucans, which are not widely distributed outside the Poaceae.Here we review current knowledge of cell wall biology in plants and highlight emerging technologies that are providing new and exciting insights into the most challenging questions related to the synthesis, re-modeling and degradation of wall polysaccharides.

View Article: PubMed Central - PubMed

Affiliation: Australian Research Council Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, SA, Australia.

ABSTRACT
Plant cell walls consist predominantly of polysaccharides and lignin. There has been a surge of research activity in plant cell wall biology in recent years, in two key areas. Firstly, in the area of human health it is now recognized that cell wall polysaccharides are key components of dietary fiber, which carries significant health benefits. Secondly, plant cell walls are major constituents of lignocellulosic residues that are being developed as renewable sources of liquid transport biofuels. In both areas, the cell walls of the Poaceae, which include the cereals and grasses, are particularly important. The non-cellulosic wall polysaccharides of the Poaceae differ in comparison with those of other vascular plants, insofar as they contain relatively high levels of heteroxylans as "core" polysaccharide constituents and relatively smaller amounts of heteromannans, pectic polysaccharides, and xyloglucans. Certain grasses and cereals walls also contain (1,3;1,4)-β-glucans, which are not widely distributed outside the Poaceae. Although some genes involved in cellulose, heteroxylan, and (1,3;1,4)-β-glucan synthesis have been identified, mechanisms that control expression of the genes are not well defined. Here we review current knowledge of cell wall biology in plants and highlight emerging technologies that are providing new and exciting insights into the most challenging questions related to the synthesis, re-modeling and degradation of wall polysaccharides.

No MeSH data available.