scholarly journals Ultrastructural development of the softwood cell wall during pyrolysis

Holzforschung ◽  
2009 ◽  
Vol 63 (2) ◽  
Author(s):  
Cordt Zollfrank ◽  
Jörg Fromm
Keyword(s):  
Cell Wall ◽  
Elemental Composition ◽  
Cellulose Microfibril ◽  
Middle Lamella ◽  
Cellulose Microfibrils ◽  
Local Orientation ◽  
Transmission Electron ◽  
Cellulose Microfibril Orientation ◽  
Novel Method ◽  
Early Degradation

Abstract The pyrolytic conversion of pine wood at mild temperatures between 200°C and 300°C was investigated by transmission electron microscopy (TEM). Based on TEM imaging and image analysis, a novel method was developed for determining the local orientation of the cellulose microfibrils in the secondary wall S2 which gives a measure for the progression of pyrolytic conversion of the cell wall. Elemental composition of pyrolysed specimens was determined up to 600°C. TEM imaging together with the evaluation of the elemental composition shows that first the polyoses are degraded, while the cellulose microfibril orientation is still visible up to 225°C. The cellulose microfibrils could not be observed at temperatures higher than 250°C, while lignin containing compound middle lamella (CML) was still visible. After a gradual decrease of the CML up to 275°C, the cell wall became entirely isotropic beginning at 300°C. Based on the presented results, we propose an early degradation of the supramolecular structure of the cell wall.

scholarly journals A novel rice fragile culm 24 mutant encodes a UDP-glucose epimerase that affects cell wall properties and photosynthesis

2020 ◽  
Vol 71 (10) ◽  
pp. 2956-2969 ◽  
Author(s):  
Ran Zhang ◽  
Huizhen Hu ◽  
Youmei Wang ◽  
Zhen Hu ◽  
Shuangfeng Ren ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cellulose Microfibril ◽  
Cellulose Microfibrils ◽  
Cell Wall Assembly ◽  
Cellulose Microfibril Orientation ◽  
Plant Photosynthesis ◽  
Altered Cell ◽  
Wall Assembly ◽  
Cell Wall Deposition ◽  
Cell Wall Properties

Abstract UDP-glucose epimerases (UGEs) are essential enzymes for catalysing the conversion of UDP-glucose (UDP-Glc) into UDP-galactose (UDP-Gal). Although UDP-Gal has been well studied as the substrate for the biosynthesis of carbohydrates, glycolipids, and glycoproteins, much remains unknown about the biological function of UGEs in plants. In this study, we selected a novel rice fragile culm 24 (Osfc24) mutant and identified it as a nonsense mutation of the FC24/OsUGE2 gene. The Osfc24 mutant shows a brittleness phenotype with significantly altered cell wall composition and disrupted orientation of the cellulose microfibrils. We found significantly reduced accumulation of arabinogalactan proteins in the cell walls of the mutant, which may consequently affect plant growth and cell wall deposition, and be responsible for the altered cellulose microfibril orientation. The mutant exhibits dwarfism and paler leaves with significantly decreased contents of galactolipids and chlorophyll, resulting in defects in plant photosynthesis. Based on our results, we propose a model for how OsUGE2 participates in two distinct metabolic pathways to co-modulate cellulose biosynthesis and cell wall assembly by dynamically providing UDP-Gal and UDP-Glc substrates.

scholarly journals Ultrastructure of Cells and Microanalysis in Malus domestica Borkh. ‘Szampion’ Fruit in Relation to Varied Calcium Foliar Feeding

Molecules ◽  
2020 ◽  
Vol 25 (20) ◽  
pp. 4622
Author(s):  
Piotr Kowalik ◽  
Tomasz Lipa ◽  
Zenia Michałojć ◽  
Mirosława Chwil
Keyword(s):  
Cell Wall ◽  
Malus Domestica ◽  
Cell Structure ◽  
Middle Lamella ◽  
Apple Fruit ◽  
Malus Domestica Borkh ◽  
X Ray ◽  
Transmission Electron ◽  
Cytoplasmic Membranes

Calcium is one of the most poorly reutilized nutrients. Its deficiencies cause various physiological disturbances and, consequently, reduce the quantity and quality of yields. Reduced content of Ca2+ ions in cells leads to development of, e.g., bitter pit in apples. Efficient and instantaneous mitigation of Ca2+ deficiencies is provided by foliar feeding. There are no detailed data on the effect of foliar feeding with various calcium forms on the cell structure or on the microanalysis and mapping of this element in apple fruit cells. Therefore, we carried out comparative studies of the ultrastructure of epidermis and hypodermis cells, to assess the content and distribution of calcium in the cell wall, cytoplasmic membrane, cytoplasm, and precipitates of Malus domestica Borkh. ‘Szampion’ fruit exposed to four Ca treatments, including the control with no additional Ca supplementation (I) and foliar applications of Ca(NO3)2 (II), CaCl2 (III), and Ca chelated with EDTA (IV). Light and transmission electron microscopy and an X-ray microanalyzer were used and showed a beneficial effect of calcium preparations on the ultrastructure of fruit epidermis and hypodermis cells, manifested in the presence of a normally developed cell wall with a regular middle lamella, preserved continuity of cytoplasmic membranes, and stabilized cell structure. In the selected elements of apical epidermis cells, the highest level of Ca2+ ions was detected in the middle lamella, cell wall, plasmalemma, and cytoplasm. The highest increase in the Ca2+ content in these cell constituents was recorded in treatment IV, whereas the lowest value of the parameters was noted in variant III.

scholarly journals Xyloglucan Is Not Essential for the Formation and Integrity of the Cellulose Network in the Primary Cell Wall Regenerated from Arabidopsis Protoplasts

Plants ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 629 ◽  
Author(s):  
Hiroaki Kuki ◽  
Ryusuke Yokoyama ◽  
Takeshi Kuroha ◽  
Kazuhiko Nishitani
Keyword(s):  
Cell Wall ◽  
Cellulose Microfibril ◽  
Mechanical Stability ◽  
Molecular Model ◽  
Primary Cell ◽  
Cellulose Microfibrils ◽  
Primary Cell Wall ◽  
Imaging Analysis ◽  
Cellulose Deposition ◽  
Initial Assembly

The notion that xyloglucans (XG) play a pivotal role in tethering cellulose microfibrils in the primary cell wall of plants can be traced back to the first molecular model of the cell wall proposed in 1973, which was reinforced in the 1990s by the identification of Xyloglucan Endotransglucosylase/Hydrolase (XTH) enzymes that cleave and reconnect xyloglucan crosslinks in the cell wall. However, this tethered network model has been seriously challenged since 2008 by the identification of the Arabidopsis thaliana xyloglucan-deficient mutant (xxt1 xxt2), which exhibits functional cell walls. Thus, the molecular mechanism underlying the physical integration of cellulose microfibrils into the cell wall remains controversial. To resolve this dilemma, we investigated the cell wall regeneration process using mesophyll protoplasts derived from xxt1 xxt2 mutant leaves. Imaging analysis revealed only a slight difference in the structure of cellulose microfibril network between xxt1 xxt2 and wild-type (WT) protoplasts. Additionally, exogenous xyloglucan application did not alter the cellulose deposition patterns or mechanical stability of xxt1 xxt2 mutant protoplasts. These results indicate that xyloglucan is not essential for the initial assembly of the cellulose network, and the cellulose network formed in the absence of xyloglucan provides sufficient tensile strength to the primary cell wall regenerated from protoplasts.

Interspecific comparison of elutable cell wall extensin precursors by transmission electron microscopy

1986 ◽  
Vol 44 ◽  
pp. 284-285
Author(s):  
J. W. Heckman ◽  
M. J. Kielszewski ◽  
D. T. A. Lamport ◽  
E. P. Muldoon ◽  
B. T. Terhune ◽  
...  
Keyword(s):  
Cell Wall ◽  
Higher Plants ◽  
Gel Filtration ◽  
Cellulose Microfibrils ◽  
Primary Cell Wall ◽  
Wall Model ◽  
Intact Cells ◽  
Transmission Electron ◽  
Macromolecular Network ◽  
Covalently Linked

In addition to cellulose microfibrils, the primary cell wall of many higher plants contains extensin, a class of hydroxyproline-rich glycoprotein (HRGP). Despite its predominately hydrophilic amino acid composition, most cell wall HRGP remains insoluble even after complete deglycosylation with anhydrous HF, suggesting a covalently linked macromolecular network. This led to the development of the "warp-weft" cell wall model, based on an extensin network ("weft") penetrated by cellulose microfibrils (the "warp")(FIG. 1). Extensin precursors elute rapidly from intact cells and cell wall preparations of tomato, carrot, and cucumber, with mild salt solutions. Tomato precursors, at least, are block copolymers of a few repeating sequences. Gel filtration data and immuno-crossreactivity suggest that tomato P2 and cucumber callus precursor are similar. TEM confirms the rod-like structure and the lengths of these molecules.

Microtubules and cell wall development in differentiating protophloem sieve elements of Triticum aestivum L

1987 ◽  
Vol 87 (4) ◽  
pp. 595-607
Author(s):  
E. P. ELEFTHERIOU
Keyword(s):  
Cell Wall ◽  
Triticum Aestivum L ◽  
Cellulose Microfibrils ◽  
Wall Material ◽  
Wall Thickening ◽  
Sieve Elements ◽  
Material Deposition ◽  
Cellulose Microfibril Orientation ◽  
Cell Wall Development ◽  
Developing Area

The densities of microtubules (MTs) along the lateral walls of developing sieve elements in root protophloem of wheat have been investigated by electron microscopy. They increase gradually in the very young sieve elements to reach a maximum just before the initiation of wall thickening. During wall increment MTs remain at high densities (more than 10 MTs μm−1), but their number declines abruptly when wall material deposition ceases. Cell wall thickening is not uniform: broad ridges alternate with narrow depressions, the latter occupied by plasmodesmata. During wall material deposition MTs overlie the thickenings only, being entirely absent from the non-thickened areas. The orientation of MTs reflects that of the currently deposited cellulose microfibrils in the cell wall, all being perpendicular to the direction of cell expansion. Numerous vesicles, apparently of Golgi apparatus origin, are encountered amongst the cortical arrays of MTs. Though the least spacing between the contiguous MTs is much smaller than the diameter of even the smallest vesicles, the latter were seen amongst the MTs, indicating that MTs do not prevent the vesicles from passing between them towards the developing area. All results favour the suggestion that MTs in sieve elements are involved in cell wall pattern development, cellulose microfibril orientation, and presumably in cell elongation.

scholarly journals Swelling of Valonia cellulose microfibrils in amine oxide systems

2008 ◽  
Vol 86 (6) ◽  
pp. 520-524 ◽  
Author(s):  
Pierre Noé ◽  
Henri Chanzy
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Electron Diffraction ◽  
Amine Oxide ◽  
Cellulose Microfibrils ◽  
Electron Diffraction Analysis ◽  
Oxide Systems ◽  
Transmission Electron ◽  
Valonia Ventricosa

Cellulose microfibrils from Valonia ventricosa cell-wall fragments were immersed into molten N-methylmorpholine-N-oxide monohydrate (NMMO·H2O), stabilized with n-propyl gallate and kept at 80 °C. The resulting ultrastructural modifications, which were followed by transmission electron microscopy and electron diffraction analysis, showed that within minutes the solvent slowly penetrated inside the crystalline microfibrils and progressed as a wedge in between the cellulose chains without cutting them. Prior to dissolution, a longitudinal subfibrillation of the initial microfibrils occurred, leading to the observation of highly swollen microfibrils, which could reach diameters up to three times larger than those of the initial samples. This mode of swelling is compared with those occurring in other systems, where the intracrystalline swelling of cellulose has been described at the ultrastructural level.Key words: cellulose swelling, Valonia cellulose, N-methylmorpholine-N-oxide.

Cellulose microfibril orientation in Oocystis solitaria: proof that microtubules control the alignment of the terminal complexes

1986 ◽  
Vol 83 (1) ◽  
pp. 223-234
Author(s):  
H. Quader
Keyword(s):  
Cellulose Microfibril ◽  
Drug Application ◽  
Freeze Fracture ◽  
Cellulose Microfibrils ◽  
Cortical Microtubules ◽  
Terminal Complex ◽  
Experimental Proof ◽  
Cellulose Deposition ◽  
Cellulose Microfibril Orientation ◽  
Terminal Complexes

In the green alga Oocystis solitaria microtubules control the regular deposition of cellulose microfibrils. Although it has frequently been suggested that the influence of the cortical microtubules is mediated through the alignment of structures in the plasma membrane, e.g. the cellulose-synthesizing enzymes, experimental proof is lacking. In Oocystis the putative cellulose-synthesizing units, the so-called terminal complexes, can be visualized following freeze-fracture. With respect to the synthesis of a given layer of microfibrils two distinct situations are observable: terminal complex doublets occur before the start of cellulose formation, but are subsequently separated into single terminal complexes by pressure exerted by the crystallizing microfibrils. In order to investigate the effect of anti-microtubular substances on the orientation of the terminal complexes, the state of cellulose deposition at the time of drug application was marked by short (15–30 min) treatment with Congo Red, which causes a morphological change in the terminal complexes. The characteristic alignment of the terminal complexes, both doublets and fragmented single ones, is severely disturbed in cells treated with the herbicide amiprophosmethyl, which is known to interfere with the action of microtubules. The results provide strong evidence that microtubules control the alignment of the putative cellulose-forming units in Oocystis. The observed pattern of interference indicates that the microtubules most probably achieve their control by imposing fluidity channels on the membrane and not via direct links with the terminal complexes.

ABNORMAL LIGNIN DISTRIBUTION IN WOOD FROM SEVERELY DROUGHT STRESSED PINUS RADIATA TREES

IAWA Journal ◽  
2002 ◽  
Vol 23 (2) ◽  
pp. 161-178 ◽  
Author(s):  
Lloyd A. Donaldson
Keyword(s):  
Cell Wall ◽  
Secondary Wall ◽  
Sand Dunes ◽  
Middle Lamella ◽  
Wood Properties ◽  
Radiata Pine ◽  
Growth Environment ◽  
Lignin Distribution ◽  
Transmission Electron ◽  
Cell Wall Development

Radiata pine logs exhibiting concentric shelling were examined for abnormal wood anatomy and cell wall characteristics. The trees from which the logs originated were growing on coastal sand dunes with a shallow impermeable iron pan subsoil, and the abnormal wood properties are assumed to be the result of frequent water stress and possible associated nutritional stress. The wood showed numerous false growth rings alternating with bands of poorly lignified tracheids. Examination of lignin distribution by confocal fluorescence microscopy and transmission electron microscopy revealed abnormal cell wall development associated with a poorly lignified middle lamella and outer secondary cell wall. Affected tracheids showed poor adhesion with development of intercellular checking, particularly on radial cell walls. Some tracheids showed concentric lamellation associated with areas of high and low lignification within the secondary wall. In many cases, the S3 layer was thicker and more heavily lignified than normal. Tracheids with the greatest reduction in lignification of the secondary wall showed evidence of collapse. The shelling behaviour of the wood was thus explained by poor or negligible adhesion between tracheids due to reduced lignification of middle lamellae. This investigation provides some insight into the effect of growth environment on lignification.

scholarly journals Anatomy and cell wall ultrastructure of sunflower stalk rind

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Lizhen Wang ◽  
Hao Ren ◽  
Shengcheng Zhai ◽  
Huamin Zhai
Keyword(s):  
Cell Wall ◽  
Middle Lamella ◽  
Transmission Electron ◽  
Vessel Elements ◽  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
Phloem Fibers ◽  
Ray Parenchyma Cells ◽  
Xylem Fibers ◽  
Anatomy And Ultrastructure

AbstractThe anatomy and ultrastructure of sunflower stalk rind are closely related to its conversion and utilization. We studied systematically the anatomy and ultrastructure of the stalk rind using light, scanning electron, transmission electron and fluorescence microscopy. The results showed that the stalk rind consisted of phloem fibers (PF), xylem fibers (XF), vessel elements (V), ground parenchyma cells (GPC), axial parenchyma cells (APC), xylem ray parenchyma cells (XRPC), and pith ray parenchyma cells (PRPC). These cell walls were divided into the middle lamella, primary wall, and secondary wall (S). It was found that the S of PF, XF and V was further divided into three layers (S1–S3), while the S of APC, GPC, XRPC and PRPC showed a non-layered cell wall organization or differentiated two (S1, S2) to seven layers (S1–S7). Our research revealed the plasmodesmata characteristics in the pit membranes (PMs) between parenchyma cells (inter-GPCs, inter-XRPCs, and inter-PRPCs). The morphology of the plasmodesmata varied with the types of parenchyma cells. The thickness and diameter of PMs between the cells (inter-Vs, V–XF, V–APC, and V–XRPC) were greater than that of PMs between parenchyma cells. The cell corners among parenchyma cells were intercellular space. The lignification degree of vessels was higher than that of parenchyma cells and fibers. The results will provide useful insights into the biological structure, conversion and utilization of sunflower stalk rind.

Transmission Electron Microscopy, Fluorescence Microscopy, and Confocal Raman Microscopic Analysis of Ultrastructural and Compositional Heterogeneity of Cornus alba L. Wood Cell Wall

2013 ◽  
Vol 19 (1) ◽  
pp. 243-253 ◽  
Author(s):  
Jianfeng Ma ◽  
Zhe Ji ◽  
Xia Zhou ◽  
Zhiheng Zhang ◽  
Feng Xu
Keyword(s):  
Cell Wall ◽  
Fluorescence Microscopy ◽  
Cell Walls ◽  
Middle Lamella ◽  
Plant Cell Walls ◽  
Cornus Alba ◽  
Transmission Electron ◽  
Pit Membrane ◽  
Ray Parenchyma

AbstractTransmission electron microscopy (TEM), fluorescence microscopy, and confocal Raman microscopy can be used to characterize ultrastructural and compositional heterogeneity of plant cell walls. In this study, TEM observations revealed the ultrastructural characterization of Cornus alba L. fiber, vessel, axial parenchyma, ray parenchyma, and pit membrane between cells, notably with the ray parenchyma consisting of two well-defined layers. Fluorescence microscopy evidenced that cell corner middle lamella was more lignified than adjacent compound middle lamella and secondary wall with variation in lignification level from cell to cell. In situ Raman images showed that the inhomogeneity in cell wall components (cellulose and lignin) among different cells and within morphologically distinct cell wall layers. As the significant precursors of lignin biosynthesis, the pattern of coniferyl alcohol and aldehyde (joint abbreviation Lignin-CAA for both structures) distribution in fiber cell wall was also identified by Raman images, with higher concentration occurring in the fiber secondary wall where there was the highest cellulose concentration. Moreover, noteworthy was the observation that higher concentration of lignin and very minor amounts of cellulose were visualized in the pit membrane areas. These complementary microanalytical methods provide more accurate and complete information with regard to ultrastructural and compositional characterization of plant cell walls.

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