Effects of Changes in Biopolymer Composition on Moisture in Acetylated Wood

To investigate the effects of changes in biopolymer composition on moisture in acetylated poplar wood (Populus euramericana Cv.), the acetylation of control wood was compared to the acetylation of wood with reduced hemicellulose or lignin content (about 9% reduction of total specimen dry weight in both cases). Time-domain nuclear magnetic resonance relaxometry of water-saturated wood gave spin–spin relaxation times (T2) of water populations, while deuteration in a sorption balance was used to characterize the hydroxyl accessibility of the wood cell walls. As expected, the acetylation of pyridine-swelled wood reduced hydroxyl accessibility and made the cell wall less accessible to water, resulting in a reduction of cell wall moisture content by about 24% compared with control wood. Hemicellulose loss per se increased the spin–spin relaxation time of cell wall water, while delignification had the opposite effect. The combined effect of hemicellulose removal and acetylation caused more than a 30% decrease of cell wall moisture content when compared with control wood. The acetylated and partially delignified wood cell walls contained higher cell wall moisture content than acetylated wood. An approximate theoretical calculation of hydroxyl accessibility for acetylated wood was in the low range, but it agreed rather well with the measured accessibility, while acetylated and partially hemicellulose-depleted and partially delignified wood for unknown reasons resulted in substantially lower hydroxyl accessibilities than the theoretical estimate.

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Silicification of wood-cell walls

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100169870 ◽

1994 ◽

Vol 52 ◽

pp. 428-429

Author(s):

S. E. Keckler ◽

D. M. Dabbs ◽

N. Yao ◽

I. A. Aksay

Keyword(s):

Electron Microscopy ◽

Cell Wall ◽

Cell Walls ◽

Lignin Content ◽

Resin Composite ◽

Middle Lamella ◽

Cellulose Fibers ◽

Complex Structures ◽

Rich Region ◽

Inorganic Precursors

Cellular organic structures such as wood can be used as scaffolds for the synthesis of complex structures of organic/ceramic nanocomposites. The wood cell is a fiber-reinforced resin composite of cellulose fibers in a lignin matrix. A single cell wall, containing several layers of different fiber orientations and lignin content, is separated from its neighboring wall by the middle lamella, a lignin-rich region. In order to achieve total mineralization, deposition on and in the cell wall must be achieved. Geological fossilization of wood occurs as permineralization (filling the void spaces with mineral) and petrifaction (mineralizing the cell wall as the organic component decays) through infiltration of wood with inorganics after growth. Conversely, living plants can incorporate inorganics into their cells and in some cases into the cell walls during growth. In a recent study, we mimicked geological fossilization by infiltrating inorganic precursors into wood cells in order to enhance the properties of wood. In the current work, we use electron microscopy to examine the structure of silica formed in the cell walls after infiltration of tetraethoxysilane (TEOS).

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The effects of thermal treatment on the nanomechanical behavior of bamboo (Phyllostachys pubescens Mazel ex H. de Lehaie) cell walls observed by nanoindentation, XRD, and wet chemistry

Holzforschung ◽

10.1515/hf-2016-0124 ◽

2017 ◽

Vol 71 (2) ◽

pp. 129-135 ◽

Cited By ~ 15

Author(s):

Yanjun Li ◽

Chengjian Huang ◽

Li Wang ◽

Siqun Wang ◽

Xinzhou Wang

Keyword(s):

Cell Wall ◽

Thermal Treatment ◽

Cell Walls ◽

Treatment Time ◽

Lignin Content ◽

Phyllostachys Pubescens ◽

X Ray Diffraction ◽

Wet Chemistry ◽

X Ray ◽

Wet Chemical

Abstract The effects of thermal treatment of bamboo at 130, 150, 170, and 190°C for 2, 4, and 6 h were investigated in terms of changes in chemical composition, cellulose crystallinity, and mechanical behavior of the cell-wall level by means of wet chemical analysis, X-ray diffraction (XRD), and nanoindentation (NI). Particularly, the reduced elastic modulus (Er), hardness (H), and creep behavior were in focus. Both the temperature and treatment time showed significant effects. Expectedly, the hemicelluloses were degraded and the relative lignin content was elevated, while the crystallinity of the cellulose moiety was increased upon thermal treatment. The Er and H data of the cell wall were increased after 6 h treatment at 190°C, from 18.4 to 22.0 GPa and from 0.45 to 0.65 GPa, respectively. The thermal treatment led to a decrease of the creep ratio (CIT) under the same conditions by ca. 28%. The indentation strain state (εi) also decreased significantly after thermal treatment during the load-holding stage.

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Lignification of spruce tracheid secondary cell walls related to longitudinal hardness and modulus of elasticity using nano-indentation

Canadian Journal of Botany ◽

10.1139/b02-091 ◽

2002 ◽

Vol 80 (10) ◽

pp. 1029-1033 ◽

Cited By ~ 41

Author(s):

W Gindl ◽

H S Gupta ◽

C Grünwald

Keyword(s):

Cell Wall ◽

Modulus Of Elasticity ◽

Cell Walls ◽

Secondary Cell Wall ◽

Lignin Content ◽

Wood Formation ◽

Nano Indentation ◽

Secondary Cell Walls ◽

Cell Wall Development ◽

The One

The lignin content and the mechanical properties of lignifying and fully lignified spruce tracheid secondary cell walls were determined using UV microscopy and nano-indentation, respectively. The average lignin content of developing tracheids was 0.10 g·g1, as compared with 0.21 g·g1 in mature tracheids. The modulus of elasticity of developing cells was on average 22% lower than the one measured in mature, fully lignified cells. For the longitudinal hardness, a larger difference of 26% was observed. As lignifying cells in the cambial zone are undergoing cell wall development, spaces in the cellulosehemicellulose structure are filled with lignin and the density of the cell wall is believed to increase. It is therefore suggested that the observed difference in modulus of elasticity between developing and fully lignified cell walls is due to the filling of spaces with lignin and an increase of the packing density of the cell wall during lignification. Although remarkably less stiff than the composite polysaccharide structure in the secondary cell wall, lignin may be considered equally hard. Therefore, the observed increase in lignin content may contribute directly to the measured increase of hardness.Key words: secondary cell wall, hardness, lignin, modulus of elasticity, wood formation.

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Effects of desiccation on temperate recalcitrant seeds: differential scanning calorimetry, gas chromatography, electron microscopy, and moisture studies on Quercusnigra and Quercusalba

Canadian Journal of Forest Research ◽

10.1139/x26-206 ◽

1996 ◽

Vol 26 (10) ◽

pp. 1813-1821 ◽

Cited By ~ 9

Author(s):

K.F. Connor ◽

F.T. Bonner ◽

J.A. Vozzo

Keyword(s):

Electron Microscopy ◽

Differential Scanning Calorimetry ◽

Cell Wall ◽

Fatty Acid ◽

Moisture Content ◽

Fatty Acid Content ◽

Heat Content ◽

Dry Weight ◽

Scanning Calorimetry ◽

Seed Moisture

Investigations into the nature of desiccation-sensitive, or recalcitant, seed behavior have as yet failed to identify exact causes of this phenomenon. Experiments with Quercusnigra L. and Quercusalba L. were conducted to examine physiological and biochemical changes brought about by seed desiccation and to determine if there were predictable changes in seed moisture content, in enthalpy (heat content) of seed moisture, in the lipid fraction, or in seed ultrastructure as viability declined. Quercusnigra intact acorn moisture contents at 50% and 5% viability were 15% and less than 14%, respectively; those of intact Q. alba at 50% and 0% viability were much higher, 32% and 22%, respectively. Generally, it was found that as the seeds of both species dried, the moisture content of the axes remained high (26–27%), even after 9 days of drying. In Q. nigra acorns, there was little difference in average percent moisture lost per day among axes, proximal cotyledon tissue, and distal cotyledon tissue. Quercusalba acorns, however, lost moisture more rapidly from the axes than from the cotyledons. This was probably caused by the longitudinal splitting of the pericarp during the drying process. Lipids composed 28.4% of the dry weight of Q. nigra and 5.7% of Q. alba dry weight. Neither individual fatty acids nor total fatty acid content exhibited definite patterns of change over the course of the experiment. The most prevalent saturated fatty acid in both species was palmitic acid, and the most common unsaturated fatty acid was generally oleic acid. Electron microscopy studies of Q. nigra showed cell wall trauma after 3 days of drying (moisture content 23%); by day 7, when moisture content had dropped to 15.6%, there was a definite dissolution of cytoplasmic density and a reduction of spherosome concentration. Quercusalba exhibited similar responses to drying, but cell wall integrity was maintained. Differential scanning calorimetry studies revealed strong relationships between onset and enthalpy values of all acorn tissues and percent germination, as did regressions involving moisture content and seed germination.

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The fate of acetyl groups and sugar components during the digestion of grass cell walls in sheep

The Journal of Agricultural Science ◽

10.1017/s0021859600028252 ◽

1977 ◽

Vol 89 (2) ◽

pp. 327-340 ◽

Cited By ~ 55

Author(s):

E. Jane Morris ◽

J. S. D. Bacon

Keyword(s):

Cell Wall ◽

Cell Walls ◽

Lignin Content ◽

Sodium Ethoxide ◽

Mesophyll Cell ◽

Cell Types ◽

Gas Liquid Chromatography ◽

Cell Wall Preparation ◽

The Relationship ◽

Isolated Cell

SummaryThe digestibilities of grass cell wall constituents determined in a digestion trial were compared with those obtained by suspending various isolated cell wall preparations in nylon bags in the rumen of a sheep. Particular attention was paid to acetyl groups and to individual sugars, which were determined in both cases by gas liquid chromatography.For dried grass and hay in the digestion trial the cell wall constituents showed digestibilities decreasing in the following order: arabinose, galactose, glucose, xylose, acetyl, lignin.For a leaf cell wall preparation derived from all cell types except mesophyll, the nylon bag technique allowed the same order of digestibilities; rhamnose and uronic acids were also measured and found to be rapidly digested. Mesophyll cell walls placed in nylon bags were more readily digested than non-mesophyll. All the sugars, and also acetyl groups, were digested to the same extent.In a grass cell wall preparation isolated from sheep faeces, tested similarly, xylose and glucose were digested to the same extent, but acetyl groups were less digested.Removal of acetyl groups, using sodium ethoxide, which left the sugar composition and lignin content unchanged, increased the digestibility particularly of the cell walls from faeces.The results are discussed with reference to the relationship between cell wall composition and digestibility.

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Overexpression of the rice BAHD acyltransferase AT10 increases xylan-bound p-coumarate and reduces lignin in Sorghum bicolor

Biotechnology for Biofuels ◽

10.1186/s13068-021-02068-9 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Yang Tian ◽

Chien-Yuan Lin ◽

Joon-Hyun Park ◽

Chuan-Yin Wu ◽

Ramu Kakumanu ◽

...

Keyword(s):

Cell Wall ◽

Sorghum Bicolor ◽

Cell Walls ◽

Lignin Content ◽

Complex Structure ◽

Enzymatic Saccharification ◽

Cellulose Microfibrils ◽

Biomass Composition ◽

Bioenergy Crops ◽

Transgenic Lines

Abstract Background The development of bioenergy crops with reduced recalcitrance to enzymatic degradation represents an important challenge to enable the sustainable production of advanced biofuels and bioproducts. Biomass recalcitrance is partly attributed to the complex structure of plant cell walls inside which cellulose microfibrils are protected by a network of hemicellulosic xylan chains that crosslink with each other or with lignin via ferulate (FA) bridges. Overexpression of the rice acyltransferase OsAT10 is an effective bioengineering strategy to lower the amount of FA involved in the formation of cell wall crosslinks and thereby reduce cell wall recalcitrance. The annual crop sorghum represents an attractive feedstock for bioenergy purposes considering its high biomass yields and low input requirements. Although we previously validated the OsAT10 engineering approach in the perennial bioenergy crop switchgrass, the effect of OsAT10 expression on biomass composition and digestibility in sorghum remains to be explored. Results We obtained eight independent sorghum (Sorghum bicolor (L.) Moench) transgenic lines with a single copy of a construct designed for OsAT10 expression. Consistent with the proposed role of OsAT10 in acylating arabinosyl residues on xylan with p-coumarate (pCA), a higher amount of p-coumaroyl-arabinose was released from the cell walls of these lines upon hydrolysis with trifluoroacetic acid. However, no major changes were observed regarding the total amount of pCA or FA esters released from cell walls upon mild alkaline hydrolysis. Certain diferulate (diFA) isomers identified in alkaline hydrolysates were increased in some transgenic lines. The amount of the main cell wall monosaccharides glucose, xylose, and arabinose was unaffected. The transgenic lines showed reduced lignin content and their biomass released higher yields of sugars after ionic liquid pretreatment followed by enzymatic saccharification. Conclusions Expression of OsAT10 in sorghum leads to an increase of xylan-bound pCA without reducing the overall content of cell wall FA esters. Nevertheless, the amount of total cell wall pCA remains unchanged indicating that most pCA is ester-linked to lignin. Unlike other engineered plants overexpressing OsAT10 or a phylogenetically related acyltransferase with similar putative function, the improvements of biomass saccharification efficiency in sorghum OsAT10 lines are likely the result of lignin reductions rather than reductions of cell wall-bound FA. These results also suggest a relationship between xylan-bound pCA and lignification in cell walls.

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Isolation and partial characterization of apiogalacturonans from the cell wall of Lemna minor

Biochemical Journal ◽

10.1042/bj1160569 ◽

1970 ◽

Vol 116 (4) ◽

pp. 569-579 ◽

Cited By ~ 76

Author(s):

David A. Hart ◽

Paul K. Kindel

Keyword(s):

Cell Wall ◽

Sodium Chloride ◽

Cell Walls ◽

Lemna Minor ◽

Extraction Procedure ◽

Ammonium Oxalate ◽

Periodate Oxidation ◽

Dry Weight ◽

Weight Basis ◽

Sephadex Column

1. A mild, reproducible extraction procedure, using 0.5% ammonium oxalate, was developed for the isolation of polysaccharides containing d-apiose from the cell wall of Lemna minor. On a dry-weight basis the polysaccharide fractions extracted with ammonium oxalate made up 14% of the material designated cell walls and contained 20% of the d-apiose originally present in the cell walls. The cell walls, as isolated, contained 83% of the d-apiose present in L. minor. 2. After extraction with ammonium oxalate, purified polysaccharides were obtained by DEAE-Sephadex column chromatography and by fractional precipitation with sodium chloride. With these procedures the material extracted at 22°C could be separated into at least five polysaccharides. On a dry-weight basis two of these polysaccharides made up more than 50% of the material extracted at 22°C. There was a direct relationship between the d-apiose content of the polysaccharides and their solubility in sodium chloride solutions; those of highest d-apiose content were most soluble. 3. All the polysaccharides isolated appeared to be of one general type, namely galacturonans to which were attached side chains containing d-apiose. The d-apiose content of the apiogalacturonans varied from 7.9 to 38.1%. The content of esterified d-galacturonic acid residues in all apiogalacturonans was low, being in the range 1.0–3.5%. Hydrolysis of a representative apiogalacturonan with dilute acid resulted in the complete removal of the d-apiose with little or no degradation of the galacturonan portion. 4. Treatment of polysaccharide fractions with pectinase established that those of high d-apiose content and soluble in m-sodium chloride were not degraded, whereas those of low d-apiose content and insoluble in m-sodium chloride were extensively degraded. When the d-apiose was removed from a typical pectinase-resistant polysaccharide, the remainder of the polysaccharide was readily degraded by this enzyme. 5. Periodate oxidation of representative polysaccharide fractions and apiogalacturonans and determination of the formaldehyde released showed that about 50% of the d-apiose molecules were substituted at either the 3- or the 3′-position.

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Unique lignin modifications pattern the nucleation of silica in sorghum endodermis

Journal of Experimental Botany ◽

10.1093/jxb/eraa127 ◽

2020 ◽

Vol 71 (21) ◽

pp. 6818-6829 ◽

Cited By ~ 3

Author(s):

Nerya Zexer ◽

Rivka Elbaum

Keyword(s):

Cell Wall ◽

Silicic Acid ◽

Cell Walls ◽

Dry Weight ◽

Cell Wall Chemistry ◽

Modified Lignin ◽

Trace Concentrations ◽

High Degree ◽

Micrometer Scale ◽

The Impact

Abstract Silicon dioxide in the form of hydrated silica is a component of plant tissues that can constitute several percent by dry weight in certain taxa. Nonetheless, the mechanism of plant silica formation is mostly unknown. Silicon (Si) is taken up from the soil by roots in the form of monosilicic acid molecules. The silicic acid is carried in the xylem and subsequently polymerizes in target sites to silica. In roots of sorghum (Sorghum bicolor), silica aggregates form in an orderly pattern along the inner tangential cell walls of endodermis cells. Using Raman microspectroscopy, autofluorescence, and scanning electron microscopy, we investigated the structure and composition of developing aggregates in roots of sorghum seedlings. Putative silica aggregation loci were identified in roots grown under Si starvation. These micrometer-scale spots were constructed of tightly packed modified lignin, and nucleated trace concentrations of silicic acid. Substantial variation in cell wall autofluorescence between Si+ and Si– roots demonstrated the impact of Si on cell wall chemistry. We propose that in Si– roots, the modified lignin cross-linked into the cell wall and lost its ability to nucleate silica. In Si+ roots, silica polymerized on the modified lignin and altered its structure. Our work demonstrates a high degree of control over lignin and silica deposition in cell walls.

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UDP-GLYCOSYLTRANSFERASE 72E3 Plays a Role in Lignification of Secondary Cell Walls in Arabidopsis

International Journal of Molecular Sciences ◽

10.3390/ijms21176094 ◽

2020 ◽

Vol 21 (17) ◽

pp. 6094

Author(s):

Fabien Baldacci-Cresp ◽

Julien Le Roy ◽

Brigitte Huss ◽

Cédric Lion ◽

Anne Créach ◽

...

Keyword(s):

Cell Wall ◽

Cell Walls ◽

Lignin Content ◽

Mutant Cell ◽

Subsequent Investigation ◽

Secondary Cell Walls ◽

Chemical Determination ◽

Safranin O

Lignin is present in plant secondary cell walls and is among the most abundant biological polymers on Earth. In this work we investigated the potential role of the UGT72E gene family in regulating lignification in Arabidopsis. Chemical determination of floral stem lignin contents in ugt72e1, ugt72e2, and ugt72e3 mutants revealed no significant differences compared to WT plants. In contrast, the use of a novel safranin O ratiometric imaging technique indicated a significant increase in the cell wall lignin content of both interfascicular fibers and xylem from young regions of ugt72e3 mutant floral stems. These results were globally confirmed in interfascicular fibers by Raman microspectroscopy. Subsequent investigation using a bioorthogonal triple labelling strategy suggested that the augmentation in lignification was associated with an increased capacity of mutant cell walls to incorporate H-, G-, and S-monolignol reporters. Expression analysis showed that this increase was associated with an up-regulation of LAC17 and PRX71, which play a key role in lignin polymerization. Altogether, these results suggest that UGT72E3 can influence the kinetics of lignin deposition by regulating monolignol flow to the cell wall as well as the potential of this compartment to incorporate monomers into the growing lignin polymer.

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Leachability and Decay Resistance of Wood Polyesterified with Sorbitol and Citric Acid

Forests ◽

10.3390/f11060650 ◽

2020 ◽

Vol 11 (6) ◽

pp. 650 ◽

Cited By ~ 2

Author(s):

Greeley Beck

Keyword(s):

Cell Wall ◽

Citric Acid ◽

Moisture Content ◽

Brown Rot ◽

Decay Resistance ◽

White Rot ◽

Modification System ◽

Sorption Behaviour ◽

Wood Modification ◽

Water Saturated

Research Highlights: Polyesterification of wood with sorbitol and citric acid (SCA) increases decay resistance against brown-rot and white-rot fungi without reducing cell wall moisture content but the SCA polymer is susceptible to hydrolysis. Background and Objectives: SCA polyesterification is a low-cost, bio-based chemical wood modification system with potential for commercialisation. Materials and Methods: This study investigates moisture-related properties and decay resistance in SCA-modified wood. Scots pine sapwood was polyesterified at 140 °C with various SCA solution concentrations ranging from 14–56% w/w. Dimensional stability was assessed and leachates were analysed with high-performance liquid chromatography (HPLC). Chemical changes were characterized with attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) and spectra were quantitatively compared with peak ratios. Low-field nuclear magnetic resonance (LFNMR) relaxometry was used to assess water saturated samples and decay resistance was determined with a modified EN113 test. Results: Anti-swelling efficiency (ASE) ranged from 23–43% and decreased at higher weight percentage gains (WPG). Reduced ASE at higher WPG resulted from increased water saturated volumes for higher treatment levels. HPLC analysis of leachates showed detectable citric acid levels even after an EN84 leaching procedure. ATR-FTIR analysis indicated increased ester content in the SCA-modified samples and decreased hydroxyl content compared to controls. Cell wall water assessed by non-freezing moisture content determined with LFNMR was found to increase because of the modification. SCA-modified samples resisted brown-rot and white-rot decay, with a potential decay threshold of 50% WPG. Sterile reference samples incubated without fungi revealed substantial mass loss due to leaching of the samples in a high humidity environment. The susceptibility of the SCA polymer to hydrolysis was confirmed by analysing the sorption behaviour of the pure polymer in a dynamic vapour sorption apparatus. Conclusions: SCA wood modification is an effective means for imparting decay resistance but, using the curing parameters in the current study, prolonged low-level leaching due to hydrolysis of the SCA polymer remains a problem.

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