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Composition and desiccation-induced alterations of the cell wall in the resurrection plant Craterostigma wilmsii (2004)

Vicré, Maïté ; Lerouxel, Olivier ; Farrant, Jill ; [et al.]

Oxford, UK; Malden , USA : Munksgaard International Publishers

Physiologia plantarum 120 (2004), S. 0

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ISSN: 1399-3054

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: 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.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.0031-9317.2004.0234.x

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2

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The role of high-mannose and complex asparagine-linked glycans in the secretion and stability of glycoproteins (1989)

Driouich, Azeddine ; Gonnet, Pascale ; Makkie, Mouna ; [et al.]

Springer

Planta 180 (1989), S. 96-104

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ISSN: 1432-2048

Keywords: Acer (glycoprotein) ; Glycoprotein ; Secretion (glycoprotein)

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Suspension-cultured cells of sycamore (Acer pseudoplatanus L.) secrete a number of acid hydrolases and other proteins that have both highmannose and complex asparagine-linked glycans. We used affinity chromatography with concanavalin A and an antiserum specific for complex glycans in conjunction with in vivo-labeling studies to show that all of the secreted proteins carry glycans. The presence of complex glycans on secretory proteins indicates that they are passing through the Golgi complex on the way to the extracellular compartment. The sodium ionophore, monensin, did not block the transport of proteins to the extracellular medium, even though monensin efficiently inhibited the Golgi-mediated processing of complex glycans. The inhibition of N-glycosylation by tunicamycin reduced by 76% to 84% the accumulation of newly synthesized (i.e. radioactively labeled) protein that was secreted by the sycamore cells, while cytoplasmic protein biosynthesis was not affected by this antibiotic. However, in the presence of glycoprotein-processing inhibitors, such as castanospermine and deoxymannojirimycin, the formation of complex glycans was prevented but glycoprotein secretion was unchanged. These results support the conclusion that N-linked glycan processing is not necessary for sorting, but glycosylation is required for accumulation of secreted proteins in the extracellular compartment.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02411415

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3

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Identification and partial characterization of proteins and proteoglycans encrusting the secondary cell walls of flax fibres (2000)

Girault, Raynald ; His, Isabelle ; Andeme-Onzighi, Christine ; [et al.]

Springer

Planta 211 (2000), S. 256-264

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ISSN: 1432-2048

Keywords: Key words: Arabinogalactan-protein ; Glycine-rich protein ; Hydroxyproline-deficient protein ; Leucine-rich protein ; Linum (cell wall) ; Secondary cell wall ; Yariv phenylglycosides

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract. Four proteins were isolated from depectinised elementary fibres of flax (Linum usitatissimum L.), using either alkali or cellulase digestion treatments. All the four proteins were characterized by a deficiency or low contents of hydroxyproline and by high levels of glutamic acid/glutamine and/or aspartic acid/asparagine. The two proteoglycans solubilized with cellulase strongly reacted with β-glucosyl Yariv reagent but not with α-glucosyl Yariv reagent and contained appreciable amounts of alanine, glycine, serine and threonine, suggesting a relationship with cell wall hydroxyproline-deficient arabinogalactan-proteins. The two alkali-extracted proteins did not show any reaction with β-glucosyl Yariv dye. Due to the harsh treatment, they might only partially represent the original proteins. Due to its high level of glycine (41%), one of these proteins might be classified as a glycine-rich protein. The latter polypeptide, of low molecular molar mass, contained 14.6% leucine and might consist of a domain related to leucine-rich proteins. The data show that these proteins and arabinogalactan-protein-like proteoglycans were strongly associated with the secondary walls of flax fibres. Their presence in small amounts (0.1–0.4%), raises the problem of their putative structural role.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s004250000281

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4

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Immunocytochemical characterization of early-developing flax fiber cell walls (2000)

Andème-Onzighi, Christine ; Girault, Raynald ; His, Isabelle ; [et al.]

Springer

Protoplasma 213 (2000), S. 235-245

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ISSN: 1615-6102

Keywords: Arabinogalactan proteins ; Fiber ; Linum usitatissimum ; Immunocytochemistry ; Polysaccharide ; Secondary wall

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Summary The deposition and formation of a thick secondary wall is a major event in the differentiation of flax (Linum usitatissimum) fibers. This wall is cellulose-rich; but it also contains significant amounts of other matrix polymers which are noncellulosic such as pectins. We have used immunocytochemical techniques with antibodies specific for various epitopes associated with either pectins or arabinogalactan proteins (AGPs) to investigate the distribution of these polymers within the walls of differentiating young fibers of 1- and 2-week-old plants. Our results show that different epitopes exhibit distinct distribution patterns within fiber walls. Unesterified pectins recognized by polygalacturonic acid-rhamnogalacturonan I (PGA/RG-I) antibodies and rhamnogalacturonan II recognized by anti-RG-II-borate complex antibodies are localized all over the secondary wall of fibers. PGA/RG-I epitopes, but not RG-II epitopes, are also present in the middle lamellae and cell junctions. In marked contrast, β-(1→4) galactans recognized by the LM5 monoclonal antibody and AGP epitopes recognized by anti-β-(1→6) galactan and LM2 antibodies are primarily located in the half of the secondary wall nearest the plasma membrane. LM2 epitopes, present in 1-week-old fibers, are undetectable later in development, suggesting a regulation of the expression of certain AGP epitopes. In addition, localization of cellulose with the cellobiohydrolase I-gold probe reveals distinct subdomains within the secondary walls of young fibers. These findings indicate that, in addition to cellulose, early-developing flax fibers synthesize and secrete different pectin and AGP molecules.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01282161

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5

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Immunolocalization of β-(1→4) and β-(1→6)-D-galactan epitopes in the cell wall and Golgi stacks of developing flax root tissues (1998)

Vicré, Maïté ; Jauneau, Alain ; Paul Knox, J. ; [et al.]

Springer

Protoplasma 203 (1998), S. 26-34

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ISSN: 1615-6102

Keywords: Flax ; Cell wall ; Golgi apparatus ; β-Galactans ; Immunocytochemistry

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Summary Most cell wall components are carbohydrate including the major matrix polysaccharides, pectins and hemicelluloses, and the arabinogalactan-protein proteoglycans. Both types of molecules are assembled in the Golgi apparatus and transported in secretory vesicles to the cell surface. We have employed antibodies specific to β-(1→6) and β-(1→4)-D-galactans, present in plant cell wall polysaccharides, in conjunction with immunofluorescence and electron microscopy to determine the location of the galactan-containing components in the cell wall and Golgi stacks of flax root tip tissues. Immunofluorescence data show that β-(1→4)-D-galactan epitopes are restricted to peripheral cells of the root cap. These epitopes are not expressed in meristematic and columella cells. In contrast, β-(1→6)-D-galactan epitopes are found in all cell types of flax roots. Immunogold labeling experiments show that both epitopes are specifically located within the wall immediately adjacent to the plasma membrane. They are also detected in Golgi cisternae and secretory vesicles, which indicates the involvement of the Golgi apparatus in their synthesis and transport. These findings demonstrate that the synthesis and localization of β-(1→4)-D-galactan epitopes are highly regulated in developing flax roots and that different β-linked D-galactans associated with cell wall polysaccharides are expressed in a cell type-specific manner.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01280584

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6

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Micro-heterogeneity of pectins and calcium distribution in the epidermal and cortical parenchyma cell walls of flax hypocotyl (1997)

Jauneau, Alain ; Quentin, Michael ; Driouich, Azeddine

Springer

Protoplasma 198 (1997), S. 9-19

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ISSN: 1615-6102

Keywords: Calcium ; Demethylation ; Epidermal wall ; Polygalacturonate ; Polygalacturonic acid-Ca2+ conformation

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Summary Pectic polysaccharides are major components of the plant cell wall matrix and are known to perform many important functions for the plant. In the course of our studies on the putative role of pectic polysaccharides in the control of cell elongation, we have examined the distribution of polygalacturonans in the epidermal and cortical parenchyma cell walls of flax seedling hypocotyls. Pectic components have been detected with (1) the nickel (Ni2+) staining method to visualize polygalacturonates, (2) monoclonal antibodies specific to low (JIM5) and highly methylesterified (JIM7) pectins and (3) a combination of subtractive treatment and PATAg (periodic acid-thiocarbohydrazide-silver proteinate) staining. In parallel, calcium (Ca2+) distribution has been imaged using SIMS microscopy (secondary ion mass spectrometry) on cryo-prepared samples and TEM (transmission electron microscopy) after precipitation of calcium with potassium pyroantimonate. Our results show that, at the tissular level, polygalacturonans are mainly located in the epidermal cell walls, as revealed by the Ni2+ staining and immunofluorescence microscopy with JIM5 and JIM7 antibodies. In parallel, Ca2+ distribution points to a higher content of this cation in the epidermal walls compared to cortical parenchyma walls. At the ultrastructural level, immunogold labeling with JIM5 and JIM7 antibodies shows a differential distribution of pectic polysaccharides within cell walls of both tissues. The acidic polygalacturonans (recognized by JIM5) held through calcium bridges are mainly found in the outer part of the external wall of epidermal cells. In contrast, the labeling of methylesterified pectins with JIM7 is slightly higher in the inner part than in the outer part of the wall. In the cortical parenchyma cells, acidic pectins are restricted to the cell junctions and the wall areas in contact with the air-spaces, whereas methylesterified pectins are evenly distributed all over the wall. In addition, the pyroantimonate precipitation method reveals a clear difference in the Ca2+ distribution in the epidermal wall, suggesting that this cation is more tightly bound to acidic pectins in the outer part than in the inner part of that wall. Our findings show that the distribution of pectic polysaccharides and the nature of their linkages differ not only between tissues, but also within a single wall of a given cell in flax hypocotyls. The differential distribution of pectins and Ca2+ in the external epidermal wall suggests a specific control of the demethylation of pectins and a central role for Ca2+ in this regulation.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01282126

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