A xylogalacturonan subunit present in the modified hairy regions of apple pectin

Schols, Henk A.; Bakx, Edwin J.; Schipper, Dick; Voragen, A.G.J.

doi:10.1016/0008-6215(95)00287-1

Cited by 176 publications

(92 citation statements)

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“…In the ripe stage, Ara, Xyl, and GalA are the predominant noncellulosic sugars in cell walls of apples of the four cultivars. Similar results have been reported before for ripe apples (Aspinall and Fanous, 1984;Schols et al, 1995;Redgwell et al, 1997). Most of the GalA in ripe apples was 4-linked, but the 3,4-GalA residues and the corresponding nonreducing t-Xyl residues present indicated the presence of a xylogalacturonans in these apples, as has been reported (Schols et al, 1995).…”

Section: Discussionsupporting

confidence: 90%

“…Similar results have been reported before for ripe apples (Aspinall and Fanous, 1984;Schols et al, 1995;Redgwell et al, 1997). Most of the GalA in ripe apples was 4-linked, but the 3,4-GalA residues and the corresponding nonreducing t-Xyl residues present indicated the presence of a xylogalacturonans in these apples, as has been reported (Schols et al, 1995). Xylogalacturonans enriched relative to HG during the apple overripening with the exception of Gala, where the relative proportions remain constant.…”

Section: Discussionsupporting

confidence: 89%

“…Two major pectic polysaccharide backbones are homogalacturonans (HGs) and rhamnogalacturonan Is (RG Is). Although the HGs are generally unbranched, xylosyl residues may be attached at the O-3 positions of the GalA residues to form xylogalacturonans (Schols et al, 1995). Four complex side chains may be added in a precise configuration to form RG IIs (O'Neill et al, 1996).…”

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Loss of Highly Branched Arabinans and Debranching of Rhamnogalacturonan I Accompany Loss of Firm Texture and Cell Separation during Prolonged Storage of Apple

2004

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Growth and maturation of the edible cortical cells of apples (Malus domestica Borkh) are accompanied by a selective loss of pectin-associated (1/4)-b-D-galactan from the cell walls, whereas a selective loss of highly branched (1/5)-a-L-arabinans occurs after ripening and in advance of the loss of firm texture. The selective loss of highly branched arabinans occurs during the overripening of apples of four cultivars (Gala, Red Delicious, Firm Gold, and Gold Rush) that varied markedly in storage life, but, in all instances, the loss prestages the loss of firm texture, measured by both breaking strength and compression resistance. The unbranched (1/5)-linked arabinans remain associated with the major pectic polymer, rhamnogalacturonan I, and their content remains essentially unchanged during overripening. However, the degree of rhamnogalacturonan I branching at the rhamnosyl residues also decreases, but only after extensive loss of the highly branched arabinans. In contrast to the decrease in arabinan content, the loss of the rhamnogalacturonan I branching is tightly correlated with loss of firm texture in all cultivars, regardless of storage time. In vitro cell separation assays show that structural proteins, perhaps via their phenolic residues, and homogalacturonans also contribute to cell adhesion. Implications of these cell wall modifications in the mechanisms of apple cortex textural changes and cell separation are discussed.Loss of firm texture and cell adhesion are ripeningassociated processes that affect fruit quality and postharvest storage. Because the pectin substances are enriched in the walls of fruit cells compared to primary walls of other growing cells and because they constitute major components of the middle lamellae, these acidic polysaccharides have long been suspected to play key roles in fruit ripening (Jarvis, 1984;Brummel and Harpster, 2001). Over the years changes in pectin composition during fruit ripening have been studied extensively in many species, but the association of biochemical changes with changes in fruit texture is still unclear. Pectin depolymerization has little impact on wall swelling and softening during tomato (Lycopersicon esculentum) fruit ripening (Smith et al., 1988), and in other instances the swelling state of several fruit walls may change markedly without significant pectin depolymerization (Redgwell et al., 1997). Rose et al. (1998) show that wall swelling and softening may be accompanied by pectin depolymerization events, but the events are either not the only requirements or they may be unrelated to ripening. One of the surprises that emerged from the completion of the Arabidopsis genome sequence is the large number of genes that putatively encode polysaccharide degrading enzymes (Arabidopsis Genome Initiative, 2000). For example, Arabidopsis contains more than 250 genes that encode enzymes that are related to those that depolymerize pectins (Henrissat et al., 2001). This significant allotment of the genome toward pectin hydrolysis forces plant biologists to rec...

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Section: Discussionsupporting

confidence: 90%

Section: Discussionsupporting

confidence: 89%

mentioning

confidence: 99%

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Loss of Highly Branched Arabinans and Debranching of Rhamnogalacturonan I Accompany Loss of Firm Texture and Cell Separation during Prolonged Storage of Apple

2004

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“…Pectins constitute a highly complex family of cell wall polysaccharides, including homogalacturonan, rhamnogalacturonan I, and rhamnogalacturonan II. Homogalacturonan domains consist of a-D-(1/4)-GalUA residues, which can be methyl esterified, acetylated, and/or substituted with b-(1/3)-Xyl residues to form xylogalacturonan (Schols et al, 1995;Willats et al, 2001;Vincken et al, 2003). Deesterified blocks of homogalacturonan can be cross-linked by calcium, leading to the formation of a gel that is believed to be involved in cell adhesion (Jarvis et al, 2003).…”

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The Organization Pattern of Root Border-Like Cells of Arabidopsis Is Dependent on Cell Wall Homogalacturonan

et al. 2009

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Border-like cells are released by Arabidopsis (Arabidopsis thaliana) root tips as organized layers of several cells that remain attached to each other rather than completely detached from each other, as is usually observed in border cells of many species. Unlike border cells, cell attachment between border-like cells is maintained after their release into the external environment. To investigate the role of cell wall polysaccharides in the attachment and organization of border-like cells, we have examined their release in several well-characterized mutants defective in the biosynthesis of xyloglucan, cellulose, or pectin. Our data show that among all mutants examined, only quasimodo mutants (qua1-1 and qua2-1), which have been characterized as producing less homogalacturonan, had an altered border-like cell phenotype as compared with the wild type. Border-like cells in both lines were released as isolated cells separated from each other, with the phenotype being much more pronounced in qua1-1 than in qua2-1. Further analysis of border-like cells in the qua1-1 mutant using immunocytochemistry and a set of anti-cell wall polysaccharide antibodies showed that the loss of the wild-type phenotype was accompanied by (1) a reduction in homogalacturonan-JIM5 epitope in the cell wall of border-like cells, confirmed by Fourier transform infrared microspectrometry, and (2) the secretion of an abundant mucilage that is enriched in xylogalacturonan and arabinogalactan-protein epitopes, in which the cells are trapped in the vicinity of the root tip.

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“…Xylogalacturonan, an α 1,4 D galacturonan to which D xylopyranose units are attached at position O 3 in the β configuration as side chains, can be found in cell walls such as japanese radish, 1) carrot, 2) soy 3) and apple. 4) In pea hull xylogalacturonan, the degree of substitution of GalA by xylose residues is 72%. GalA residues carry mainly single terminal xylose residues attached on O 3 and a few short side chains of xylosyl residues linked on O 2 or sometimes on O 3.…”

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confidence: 99%

Fungal Exo-acting Enzymes with Novel Catalytic Properties

Sakamoto¹

2006

J. Appl. Glycosci.

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Pectins are acidic polysaccharides of high molar mass and one of the main components of the primary cell walls of dicotyledons. Pectins consist of homogalacturonic or smooth regions, and rhamnogalacturonic or hairy regions carrying neutral sugar side chains. GalA residues may be substituted by different compounds such as methanol, acetic acid and xylose, in the smooth as well as in the hairy region. The carboxyl groups of pectin are partially esterified with methanol, and the hydroxyl groups at position 2 or and 3 of GalA residues are sometimes acetylated. Xylogalacturonan, an α 1,4 D galacturonan to which D xylopyranose units are attached at position O 3 in the β configuration as side chains, can be found in cell walls such as japanese radish, 1) carrot, 2) soy 3) and apple. 4) In pea hull xylogalacturonan, the degree of substitution of GalA by xylose residues is 72%. GalA residues carry mainly single terminal xylose residues attached on O 3 and a few short side chains of xylosyl residues linked on O 2 or sometimes on O 3. 5) In contrast, arabinans and arabinogalactans are most frequently found in hairy regions of pectins. Sugar beet and apple pectins are characterized as containing high amounts of branched L arabinan, a highly branched α 1,5 L arabinan possessing 1,2 or 1,3 α linked L arabinofuranosyl residues as side chains. Arabinogalactan, which has a linear chain of β 1,4 D galactan to which α 1,5 L linked arabinofuranooligosaccharides are bound in side chains, is rich in soybean pectin. Extensive degradation of pectic polysaccharides is important in the processing of plant materials such as the clarification of fruit juices. 6) Enzymatic degradation of pectic polysaccharides is also efficient for their structural analysis since enzymes have strict substrate specificities. Exo acting enzymes are especially useful in this field because they can split polysaccharides from the terminus sequentially.This paper deals with characterizations of exo acting enzymes with novel catalytic properties, which include two A. niger exo PGs and a P. chrysogenum exo arabinanase.

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A xylogalacturonan subunit present in the modified hairy regions of apple pectin

Cited by 176 publications

References 32 publications

Loss of Highly Branched Arabinans and Debranching of Rhamnogalacturonan I Accompany Loss of Firm Texture and Cell Separation during Prolonged Storage of Apple

Loss of Highly Branched Arabinans and Debranching of Rhamnogalacturonan I Accompany Loss of Firm Texture and Cell Separation during Prolonged Storage of Apple

The Organization Pattern of Root Border-Like Cells of Arabidopsis Is Dependent on Cell Wall Homogalacturonan

Fungal Exo-acting Enzymes with Novel Catalytic Properties

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