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Mei Hong - One of the best experts on this subject based on the ideXlab platform.
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Multidimensional solid-state NMR spectroscopy of plant Cell Walls
Solid State Nuclear Magnetic Resonance, 2016Co-Authors: Tuo Wang, Pyae Phyo, Mei HongAbstract:Plant biomass has become an important source of bio-renewable energy in modern society. The molecular structure of plant Cell Walls is difficult to characterize by most atomic-resolution techniques due to the insoluble and disordered nature of the Cell wall. Solid-state NMR (SSNMR) spectroscopy is uniquely suited for studying native hydrated plant Cell Walls at the molecular level with chemical resolution. Significant progress has been made in the last five years to elucidate the molecular structures and interactions of Cellulose and matrix polysaccharides in plant Cell Walls. These studies have focused on primary Cell Walls of growing plants in both the dicotyledonous and grass families, as represented by the model plants Arabidopsis thaliana, Brachypodium distachyon, and Zea mays. To date, these SSNMR results have shown that 1) Cellulose, hemiCellulose, and pectins form a single network in the primary Cell wall; 2) in dicot Cell Walls, the protein expansin targets the hemiCellulose-enriched region of the Cellulose microfibril for its wall-loosening function; and 3) primary wall Cellulose has polymorphic structures that are distinct from the microbial Cellulose structures. This article summarizes these key findings, and points out future directions of investigation to advance our fundamental understanding of plant Cell wall structure and function.
Michael C. Jarvis - One of the best experts on this subject based on the ideXlab platform.
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comparative structure and biomechanics of plant primary and secondary Cell Walls
Frontiers in Plant Science, 2012Co-Authors: Daniel Cosgrove Cosgrove, Michael C. JarvisAbstract:Recent insights into the physical biology of plant Cell Walls are reviewed, summarizing the essential differences between primary and secondary Cell Walls and identifying crucial gaps in our knowledge of their structure and biomechanics. Unexpected parallels are identified between the mechanism of expansion of primary Cell Walls during growth and the mechanisms by which hydrated wood deforms under external tension. There is a particular need to revise current “cartoons” of plant Cell Walls to be more consistent with data from diverse approaches and to go beyond summarizing limited aspects of Cell Walls, serving instead as guides for future experiments and for the application of new techniques.
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Polymer mobility in Cell Walls of cucumber hypocotyls.
Phytochemistry, 1999Co-Authors: K. M. Fenwick, David C. Apperley, Daniel J. Cosgrove, Michael C. JarvisAbstract:Abstract Cell Walls were prepared from the growing region of cucumber ( Cucumis sativus ) hypocotyls and examined by solid-state 13 C NMR spectroscopy in both enzymically active and inactivated states The rigidity of individual polymer segments within the hydrated Cell Walls was assessed from the proton magnetic relaxation parameter T 2 and from the kinetics of cross-polarisation from 1 H to 13 C The microfibrils including most of the xyloglucan in the Cell wall as well as Cellulose behaved as very rigid solids A minor xyloglucan fraction which may correspond to cross-links between microfibrils shared a lower level of rigidity with some of the pectic galacturonan Other pectins including most of the galactan side-chain residues of rhamnogalacturonan I were much more mobile and behaved in a manner intermediate between the solid and liquid states The only difference observed between the enzymically active and inactive Cell Walls was the loss of a highly mobile methyl-esterified galacturonan fraction as the result of pectinesterase activity © 1999 Elsevier Science Ltd All rights reserved
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Control of thickness of collenchyma Cell Walls by pectins
Planta, 1992Co-Authors: Michael C. JarvisAbstract:Near-isotropic stresses were generated within collenchyma Cell Walls of celery (Apium graveolens L.) by exchanging K+ for Ca2+ ions, varying the ionic strength and de-esterifying the pectic carboxyl groups, treatments that changed the free-charge density of the pectic polysaccharides. The collenchyma strands swelled radially with increasing free-charge density but there was very little longitudinal swelling. Depolymerising the pectins by β-elimination also induced much more radial than longitudinal swelling. Supported by earlier work on Nitella, these results indicate that pectins control the interlamellar spacing in Cell Walls and hold them together across their thickness, particularly against turgor stresses tending to delaminate the Walls at the Cell corners.
Philip J. Harris - One of the best experts on this subject based on the ideXlab platform.
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The distribution of ester-linked ferulic acid in the Cell Walls of angiosperms
Phytochemistry Reviews, 2010Co-Authors: Philip J. Harris, Jason A. K. TretheweyAbstract:Ester-linked ferulic acid occurs in the Cell Walls of two major groups of angiosperms, the commelinid monocotyledons and the ‘core’ Caryophyllales, at concentrations >3.5 mg g^−1 Cell Walls, and has been detected in primary Cell Walls by its autofluorescence using ultraviolet fluorescence microscopy. Both of these groups are resolved as monophyletic clades in phylogenetic trees constructed using gene sequences. In the primary Cell Walls of the commelinid monocotyledons, including the grasses (family Poaceae), the ferulic acid is ester-linked to the non-Cellulosic polysaccharide glucuronoarabinoxylan. In contrast, in the ‘core’ Caryophyllales, the ferulic acid is ester-linked to the side chain arabinans and galactans of the pectic polysaccharide rhamnogalacturonan-1, at least in the family Amaranthaceae. In the Walls of both angiosperm groups, a range of dehydrodiferulates have also been found. These are formed oxidatively via radical coupling and result in the cross linking of the polysaccharides to which they are attached. Much lower concentrations of ester-linked ferulic acid have been found in Cell Walls isolated from other angiosperms, although physiological stress conditions may cause increases in these concentrations. The polysaccharides to which the ferulic acid is attached to in the Cell Walls of these other angiosperms is unknown.
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Atomic force microscopy of microfibrils in primary Cell Walls
Planta, 2003Co-Authors: Lynette M. Davies, Philip J. HarrisAbstract:Examination of angiosperm primary Cell Walls by transmission electron microscopy shows that they contain microfibrils that probably consist of Cellulose microfibrils surrounded by associated non-Cellulosic polysaccharides. Previous studies using solid-state 13C NMR spectroscopy have shown that the Cellulose is all crystalline with crystallites of cross-sectional dimensions of 2–3 nm. However, it is not known if each microfibril contains only one, or more than one crystallite because there is no agreement about the dimensions of the microfibrils. Partially hydrated primary Cell Walls isolated from onion (Allium cepa L.) and Arabidopsis thaliana (L.) Heynh. were examined by atomic force microscopy and the microfibril diameters determined. The Cell Walls of both species contained tightly interwoven microfibrils of uniform diameter: 4.4±0.13 nm in the onion and 5.8±0.17 nm in A. thaliana. The effect was also examined of extracting the A. thaliana Cell Walls to remove pectic polysaccharides. The microfibrils in the extracted Cell Walls of A. thaliana were significantly narrower (3.2±0.13 nm) than those in untreated Walls. The results are consistent with the microfibrils containing only one Cellulose crystallite.
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The polysaccharide composition of Poales Cell Walls: Poaceae Cell Walls are not unique
Biochemical Systematics and Ecology, 1999Co-Authors: Bronwen G Smith, Philip J. HarrisAbstract:Abstract Monocotyledon families can be divided into two groups depending on the presence (Group A) or absence (Group B) of ferulic acid ester-linked to their unlignified Cell Walls. The two groups also differ in the major types of non-Cellulosic polysaccharides in their unlignified Cell Walls: in Group A they are glucuronoarabinoxylans (GAXs), and in Group B they are pectic polysaccharides. Previous studies suggested that among the Group A families, the Poaceae (grasses and cereals) was the only family with unlignified Cell Walls containing (1→3,1→4)- β - d -glucans. Moreover, the unlignified Cell Walls of the Poaceae contain a smaller proportion of pectic rhamnogalacturonans than those of the other Group A families. However, these studies did not include other families in the order Poales. We examined the polysaccharide compositions of unlignified Cell Walls from species of six Poales families: Anarthriaceae, Centrolepidaceae, Ecdeiocoleaceae, Flagellariaceae, Poaceae, and Restionaceae. The Cell Walls of all the species examined contained (1→3,1→4)- β -glucans with the exception of two Restionaceae species; these Cell Walls also contained similar, small proportions of pectic rhamnogalacturonans. Glucuronoarabinoxylans were a major component of these Cell Walls and smaller amounts of xyloglucans and glucomannans or galactoglucomannans were also present. We found the polysaccharide compositions of the lignified Cell Walls were similar and differed in similar ways from the polysaccharide compositions of unlignified Cell Walls from the same species. Our results are discussed in relation to the possible evolution of Poales families.
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polysaccharide composition of unlignified Cell Walls of pineapple ananas comosus l merr fruit
Plant Physiology, 1995Co-Authors: Bronwen G Smith, Philip J. HarrisAbstract:The polysaccharides of Cell Walls isolated from the fleshy, edible part of the fruit of the monocotyledon pineapple [Ananas comosus (L.) Merr.] (family Bromeliaceae) were analyzed chemically. These Cell Walls were derived mostly from parenchyma Cells and were shown histochemically to be unlignified, but they contained esterlinked ferulic acid. The analyses indicated that the nonCellulosic polysaccharide composition of the Cell Walls was intermediate between that of unlignified Cell Walls of species of the monocotyledon family Poaceae (grasses and cereals) and that of unlignified Cell Walls of dicotyledons. Glucuronoarabinoxylans were the major non-Cellulosic polysaccharides in the pineapple Cell Walls. Xyloglucans were also present, together with small amounts of pectic polysaccharides and glucomannans (or galactoglucomannans). The large amounts of glucuronoarabinoxylans and small amounts of pectic polysaccharides resemble the nonCellulosic polysaccharide composition of the unlignified Cell Walls of the Poaceae. However, the absence of (1 ->3,1 ->4)-[beta]-glucans, the presence of relatively large amounts of xyloglucans, and the possible structure of the xyloglucans resemble the nonCellulosic polysaccharide composition of the unlignified Cell Walls of dicotyledons.
Jean Marc Brillouet - One of the best experts on this subject based on the ideXlab platform.
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Interactions of condensed tannins with Saccharomyces cerevisiae yeast Cells and Cell Walls: tannin location by microscopy
Journal of Agricultural and Food Chemistry, 2015Co-Authors: Julie Mekoue Nguela, Aude Vernhet, Nathalie Sieczkowski, Jean Marc BrillouetAbstract:Interactions between grape tannins/red wine polyphenols and yeast Cells/Cell Walls was previously studied within the framework of red wine aging and the use of yeast-derived products as an alternative to aging on lees. Results evidenced a quite different behavior between whole Cells (biomass grown to elaborate yeast-derived products, inactivated yeast, and yeast inactivated after autolysis) and yeast Cell Walls (obtained from mechanical disruption of the biomass). Briefly, whole Cells exhibited a high capacity to irreversibly adsorb grape and wine tannins, whereas only weak interactions were observed for Cell Walls. This last point was quite unexpected considering the literature and called into question the real role of Cell Walls in yeasts' ability to fix tannins. In the present work, tannin location after interactions between grape and wine tannins and yeast Cells and Cell Walls was studied by means of transmission electron microscopy, light epifluorescence, and confocal microscopy. Microscopy observations evidenced that if tannins interact with Cell Walls, and especially Cell wall mannoproteins, they also diffuse freely through the Walls of dead Cells to interact with their plasma membrane and cytoplasmic components.
Tuo Wang - One of the best experts on this subject based on the ideXlab platform.
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Multidimensional solid-state NMR spectroscopy of plant Cell Walls
Solid State Nuclear Magnetic Resonance, 2016Co-Authors: Tuo Wang, Pyae Phyo, Mei HongAbstract:Plant biomass has become an important source of bio-renewable energy in modern society. The molecular structure of plant Cell Walls is difficult to characterize by most atomic-resolution techniques due to the insoluble and disordered nature of the Cell wall. Solid-state NMR (SSNMR) spectroscopy is uniquely suited for studying native hydrated plant Cell Walls at the molecular level with chemical resolution. Significant progress has been made in the last five years to elucidate the molecular structures and interactions of Cellulose and matrix polysaccharides in plant Cell Walls. These studies have focused on primary Cell Walls of growing plants in both the dicotyledonous and grass families, as represented by the model plants Arabidopsis thaliana, Brachypodium distachyon, and Zea mays. To date, these SSNMR results have shown that 1) Cellulose, hemiCellulose, and pectins form a single network in the primary Cell wall; 2) in dicot Cell Walls, the protein expansin targets the hemiCellulose-enriched region of the Cellulose microfibril for its wall-loosening function; and 3) primary wall Cellulose has polymorphic structures that are distinct from the microbial Cellulose structures. This article summarizes these key findings, and points out future directions of investigation to advance our fundamental understanding of plant Cell wall structure and function.