Xylem Anatomy and Cell Wall Ultrastructure of Nicotiana Tabacum After Lignin Genetic Modification Through Transcriptional Activator EgMYB2

The transcriptional activator EgMYB2, which belongs to the large R2R3 MYB transcription factor family, plays a major role in the coordinated control of genes in the lignin biosynthetic pathway. Given that lignin genetic modification can lead to xylem alterations compromising vascular functionality, we characterised wood anatomical properties of two transgenic tobacco lines over-expressing EgMYB2, using light, fluorescence, confocal, transmission electron microscopy, immunocytochemical labelling and digital image analysis. Transgenic wood, compared with wild type, was characterised by both reduced frequency of larger vessels and lower vessel grouping; these traits are known to have physiological implications in terms of water transport efficiency and safety against embolism. Transgenic wood also appeared denser due to the occurrence of thicker cell walls and higher incidence of fibres than wild type. Increased lignin content was accompanied by a concomitant increase in cellulose and xylan, but no alterations in the usual distribution of guaiacyl and syringyl units in secondary cell walls were observed. Altogether, these results show that EgMYB2 is a master regulator controlling the synthesis of the three major polymers of the secondary cell wall and that its overexpression has significant influence on quantitative anatomical traits of wood which affect its functional properties.

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Distribution of wood polymers within the cell wall of transgenic aspen imaged by Raman microscopy

Holzforschung ◽

10.1515/hf-2011-0126 ◽

2012 ◽

Vol 66 (6) ◽

pp. 717-725 ◽

Cited By ~ 10

Author(s):

Laszlo Horvath ◽

Ilona Peszlen ◽

Notburga Gierlinger ◽

Perry Peralta ◽

Steve Kelley ◽

...

Keyword(s):

Cell Wall ◽

Genetic Modification ◽

Lignin Content ◽

Middle Lamella ◽

Raman Microscopy ◽

Confocal Raman Microscopy ◽

Wild Type ◽

Transgenic Aspen ◽

Composition And Structure ◽

G Ratio

Abstract Little is known about the effect of genetic modification on the chemical composition and structure of wood, which could have a significant effect on reactivity during chemical and enzymatic processing. In this study, information was collected by confocal Raman microscopy (CRM) on the spatial distribution of lignin and polysaccharides in the cell wall of young transgenic aspen with reduced lignin content, increased syringyl/guaiacyl (S/G) ratio, and simultaneously reduced lignin content and increased S/G ratio. CRM revealed that the lignin content of the cell wall and compound middle lamella was reduced by the genetic modification. A higher volume of water was also found in the cell wall of transgenic aspen compared with wild-type aspen, indicating an increase in the hydrophilicity of the cell wall.

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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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Hypolignification: A Decisive Factor in the Development of Hyperhydricity

Plants ◽

10.3390/plants10122625 ◽

2021 ◽

Vol 10 (12) ◽

pp. 2625

Author(s):

Nurashikin Kemat ◽

Richard G. F. Visser ◽

Frans A. Krens

Keyword(s):

Cell Wall ◽

Lignin Content ◽

Coumaric Acid ◽

Wild Type ◽

Higher Plant ◽

Gene Coding ◽

Phenylpropanoid Biosynthesis ◽

Total Lignin ◽

Total Lignin Content

One of the characteristics of hyperhydric plants is the reduction of cell wall lignification (hypolignification), but how this is related to the observed abnormalities of hyperhydricity (HH), is still unclear. Lignin is hydrophobic, and we speculate that a reduction in lignin levels leads to more capillary action of the cell wall and consequently to more water in the apoplast. p-coumaric acid is the hydroxyl derivative of cinnamic acid and a precursor for lignin and flavonoids in higher plant. In the present study, we examined the role of lignin in the development of HH in Arabidopsis thaliana by checking the wild-types (Ler and Col-0) and mutants affected in phenylpropanoid biosynthesis, in the gene coding for cinnamate 4-hydroxylase, C4H (ref3-1 and ref3-3). Exogenously applied p-coumaric acid decreased the symptoms of HH in both wild-type and less-lignin mutants. Moreover, the results revealed that exogenously applied p-coumaric acid inhibited root growth and increased the total lignin content in both wild-type and less-lignin mutants. These effects appeared to diminish the symptoms of HH and suggest an important role for lignin in HH.

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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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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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The unusual cell wall of the Lyme disease spirochaete Borrelia burgdorferi is shaped by a tick sugar

Nature Microbiology ◽

10.1038/s41564-021-01003-w ◽

2021 ◽

Vol 6 (12) ◽

pp. 1583-1592

Author(s):

Tanner G. DeHart ◽

Mara R. Kushelman ◽

Sherry B. Hildreth ◽

Richard F. Helm ◽

Brandon L. Jutras

Keyword(s):

Cell Wall ◽

Lyme Disease ◽

Borrelia Burgdorferi ◽

Cell Walls ◽

Structural Strength ◽

Cell Envelope ◽

Wild Type ◽

Tick Vector ◽

Cell Wall Alteration ◽

Main Component

AbstractPeptidoglycan—a mesh sac of glycans that are linked by peptides—is the main component of bacterial cell walls. Peptidoglycan provides structural strength, protects cells from osmotic pressure and contributes to shape. All bacterial glycans are repeating disaccharides of N-acetylglucosamine (GlcNAc) β-(1–4)-linked to N-acetylmuramic acid (MurNAc). Borrelia burgdorferi, the tick-borne Lyme disease pathogen, produces glycan chains in which MurNAc is occasionally replaced with an unknown sugar. Nuclear magnetic resonance, liquid chromatography–mass spectroscopy and genetic analyses show that B. burgdorferi produces glycans that contain GlcNAc–GlcNAc. This unusual disaccharide is chitobiose, a component of its chitinous tick vector. Mutant bacteria that are auxotrophic for chitobiose have altered morphology, reduced motility and cell envelope defects that probably result from producing peptidoglycan that is stiffer than that in wild-type bacteria. We propose that the peptidoglycan of B. burgdorferi probably evolved by adaptation to obligate parasitization of a tick vector, resulting in a biophysical cell-wall alteration to withstand the atypical torque associated with twisting motility.

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An R2R3-MYB Transcription Factor PgFLP Directly Activates PgPIN10 to Regulate the GSA of Adventitious Root in Pomegranate

10.21203/rs.3.rs-123516/v1 ◽

2020 ◽

Author(s):

Zenghui Wang ◽

Jialin Li ◽

Xuemei Yang ◽

Haixia Tang ◽

Lijuan Feng ◽

...

Keyword(s):

Transcription Factor ◽

Adventitious Root ◽

Molecular Mechanisms ◽

Lateral Roots ◽

Myb Transcription Factor ◽

Wild Type ◽

Set Point ◽

Root Gravitropism ◽

Gravity Signal ◽

R2r3 Myb

Abstract Background: The self-rooted seedling is widely used in pomegranate planting industry currently; However, the root system of self-rooted seedling is shallow and poor cold resistance. Therefore, the study of the molecular mechanisms of pomegranate adventitious root gravitropism is very important for developing deep-rooted pomegranate cultivars.Results: We report the pomegranate FOUR LIPS (PgFLP) that play an key role in regulating the gravitropic set-point angle of pomegranate adventitious root in response to gravity signal. In our study, PgFLP directly regulates the transcriptional expression of PgPIN10 by binding to its promoter, thus regulating the GSA of adventitious root in pomegranate. Additionally, the 35S::PgFLP show stronger gravitational response than wild-type, leading to a smaller GSA in Arabidopsis lateral roots, indicating that PgFLP participates in regulating the GSA of adventitious root via PgPIN10 in pomegranate. Conclusion: Our results confirm that the transcriptional regulation of PgPIN10 by R2R3-MYB transcription factor PgFLP in setting the gravitropic set-point angle of pomegranate adventitious root in response to gravity signal.

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Cytokinesis in fra2 Arabidopsis thaliana p60-katanin Mutant: Defects in Cell Plate/Daughter Wall Formation

10.20944/preprints202101.0226.v1 ◽

2021 ◽

Author(s):

Emmanuel Panteris ◽

Anna Kouskouveli ◽

Dimitris Pappas ◽

Ioannis-Dimosthenis S. Adamakis

Keyword(s):

Arabidopsis Thaliana ◽

Cell Wall ◽

Cell Walls ◽

Higher Plants ◽

Cell Plate ◽

Wild Type ◽

Microtubule Organization ◽

Root Cells ◽

Wall Formation ◽

In The Wild

Cytokinesis is accomplished in higher plants by the phragmoplast, creating and conducting the cell plate, to separate daughter nuclei by a new cell wall. The microtubule-severing enzyme p60-katanin plays an important role in the centrifugal expansion and timely disappearance of phragmoplast microtubules. Consequently, aberrant structure and delayed expansion rate of the phragmoplast occur in p60-katanin mutants. Here, the consequences of p60-katanin malfunction in cell plate/daughter wall formation were investigated by transmission electron microscopy (TEM), while deviations in the chemical composition of cell plate/new cell wall were identified by immunolabeling and confocal microscopy, in root cells of the fra2 Arabidopsis thaliana mutant. It was found that, apart from defective phragmoplast microtubule organization, cell plates/new cell walls appeared also faulty in structure, being unevenly thick and perforated by large gaps. In addition, demethylesterified homogalacturonans were prematurely present in fra2 cell plates, while callose content was significantly lower than in the wild-type. Furthermore, KNOLLE syntaxin disappeared from newly formed cell walls in fra2 earlier than in the wild-type. Taken together, these observations indicate that delayed cytokinesis, due to faulty phragmoplast organization and expansion, results in a loss of synchronization between cell plate growth and its chemical maturation.

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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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