scholarly journals Cell wall thickening in developing tension wood of artificially bent poplar trees

IAWA Journal ◽  
2015 ◽  
Vol 36 (1) ◽  
pp. 44-57 ◽  
Author(s):  
Raoufeh Abedini ◽  
Bruno Clair ◽  
Kambiz Pourtahmasi ◽  
Françoise Laurans ◽  
Olivier Arnould
Keyword(s):  
Tensile Stress ◽  
Tension Wood ◽  
Secondary Wall ◽  
Low Cost ◽  
Growing Season ◽  
Progressive Increase ◽  
Wall Layer ◽  
Wall Thickening ◽  
Normal Wood ◽  
Wood Fibres

Trees can control their shape and resist gravity thanks to their ability to produce wood under tensile stress. This stress is known to be produced during the maturation of wood fibres but the mechanism of its generation remains unclear. This study focuses on the formation of the secondary wall in tension wood produced in artificially tilted poplar saplings. Thickness of secondary wall layer (SL) and gelatinous layer (GL) were measured from cambium to mature wood in several trees sampled at different times after tilting. Measurements on wood fibres produced before tilting show the progressive increase of secondary wall thickness during the growing season. After the tilting date, SL thickness decreased markedly from normal wood to tension wood while the total thickness increased compared to normal wood, with the development of a thick GL. However, even after GL formation, SL thickness continues to increase during the growing season. GL thickening was observed to be faster than SL thickening. The development of the unlignified GL is proposed to be a low cost, efficient strategy for a fast generation of tensile stress in broadleaved trees.

The nature of reaction wood. IV. Variations in cell wall organization of tension wood fibres

1955 ◽  
Vol 3 (2) ◽  
pp. 177 ◽  
Author(s):  
AB Wardrop ◽  
HE Dadswell
Keyword(s):  
Cell Wall ◽  
Tension Wood ◽  
Secondary Wall ◽  
Degree Of Crystallinity ◽  
Tropical Species ◽  
Normal Wood ◽  
Reaction Wood ◽  
Gelatinous Layer ◽  
Wood Fibres ◽  
Cell Wall Organization

The cell wall organization, the cell wall texture, and the degree of lignification of tension wood fibres have been investigated in a wide variety of temperate and tropical species. Following earlier work describing the cell wall structure of tension wood fibres, two additional types of cell wall organization have been observed. In one of these, the inner thick "gelatinous" layer which is typical of tension wood fibres exists in addition to the normal three-layered structure of the secondary wall; in the other only the outer layer of the secondary wall and the thick gelatinous layer are present. In all the tension wood examined the micellar orientation in the inner gelatinous layer has been shown to be nearly axial and the cellulose of this layer found to be in a highly crystalline state. A general argument is presented as to the meaning of differences in the degree, of crystallinity of cellulose. The high degree of crystallinity of cellulose in tension wood as compared with normal wood is attributed to a greater degree of lateral order in the crystalline regions of tension wood, whereas the paracrystalline phase is similar in both cases. The degree of lignification in tension wood fibres has been shown to be extremely variable. However, where the degree of tension wood development is marked as revealed by the thickness of the gelatinous layer the lack of lignification is also most marked. Severity of tension wood formation and lack of lignification have also been correlated with the incidence of irreversible collapse in tension wood. Such collapse can occur even when no whole fibres are present, e.g. in thin cross sections. Microscopic examination of collapsed samples of tension wood has led to the conclusion that the appearance of collapse in specimens containing tendon wood can often be attributed in part to excessive shrinkage associated with the development of fissures between cells, although true collapse does also occur. Possible explanations of the irreversible shrinkage and collapse of tension wood fibres are advanced.

Microfibril Angle Distribution of Poplar Tension Wood

IAWA Journal ◽  
2012 ◽  
Vol 33 (4) ◽  
pp. 431-439 ◽  
Author(s):  
Silke Lautner ◽  
Cordt Zollfrank ◽  
Jörg Fromm
Keyword(s):  
Electron Microscopy ◽  
Tension Wood ◽  
Microfibril Angle ◽  
Cellulose Microfibrils ◽  
Normal Wood ◽  
Angle Distribution ◽  
Transmission Electron ◽  
Wood Fibres ◽  
Characteristic Features ◽  
Fibril Angle

Tension wood of poplar (Populus nigra) branches was studied by lightand electron microscopy. The characteristic features of tension wood such as wider growth rings, reduced vessel density and higher gross density were confirmed by our results. Based on a novel combination of transmission electron microscopy (TEM) imaging and image analysis, involving Fourier transformation, the orientation of cellulose microfibrils in the S2- and G-layer was determined. Within the G-layer microfibril angle (MFA) was parallel to the growth axis (0°). However, in the S2 it was 13° in tension wood fibres and 4° in normal wood fibres. With the exception of the relatively low fibril angle in the S2 of tension wood fibres (13°) the results are in good agreement with those of the literature.

In situ detection of laccase activity and immunolocalisation of a compression-wood-specific laccase (CoLac1) in differentiating xylem of Chamaecyparis obtusa

2016 ◽  
Vol 43 (6) ◽  
pp. 542 ◽  
Author(s):  
Hideto Hiraide ◽  
Masato Yoshida ◽  
Saori Sato ◽  
Hiroyuki Yamamoto
Keyword(s):  
Cell Wall ◽  
Secondary Wall ◽  
Compression Wood ◽  
Laccase Activity ◽  
Outer Part ◽  
Chamaecyparis Obtusa ◽  
Wall Layer ◽  
Wall Thickening ◽  
Lignin Concentration

The secondary cell wall of compression wood tracheids has a highly lignified region (S2 L) in its outermost portion. To better understand the mechanism of S2 L formation, we focussed on the activity of laccase (a monolignol oxidase) and performed in situ studies of this enzyme in differentiating compression wood. Staining of differentiating compression wood demonstrated that laccase activity began in all cell wall layers before the onset of lignification. We detected no activity of peroxidase (another monolignol oxidase) in any cell wall layer. Thus, laccase likely plays the major role in monolignol oxidisation during compression wood differentiation. Laccase activity was higher in the S2 L region than in other secondary wall regions, suggesting that this enzyme was responsible for the high lignin concentration in this region of the cell wall. Immunolabelling demonstrated the expression of a compression-wood-specific laccase (CoLac1) immediately following the onset of secondary wall thickening, this enzyme was localised to the S2 L region, whereas much less abundant in the S1 layer or inner S2 layer. Thus, the CoLac1 protein is most likely localised to the outer part of S2 and responsible for the high lignin concentration in the S2 L region.

Zeitliche Einordnung der G-Schicht-Auflagerung in den Prozess der Zellwandbildung bei Zugholzfasern in Zitterpappeln | On the chronology of g-layer formation during cell wall differentiation in tension wood fibres of poplars

2004 ◽  
Vol 155 (12) ◽  
pp. 523-527 ◽  
Author(s):  
Daniel Keunecke ◽  
Sebastian Baum
Keyword(s):  
Cell Wall ◽  
Tension Wood ◽  
Early Stage ◽  
Wall Layer ◽  
Deciduous Trees ◽  
Layer Formation ◽  
Cell Wall Layer ◽  
Wood Fibres ◽  
Additional Cell ◽  
Secondary Wall Formation

The tension wood of some deciduous trees is characterised by fibres that form an additional cell wall layer, the so-called «gelatinous layer» (g-layer). The chronology of g-layer formation in the process of cell wall differentiation and lignification was investigated using two-year old poplars (Populus tremula L.). For this purpose the pinning-method was applied. The results show that the g-layer formation probably takes place at an early stage of secondary wall formation.

scholarly journals Diversity in the organisation and lignification of tension wood fibre walls – A review

IAWA Journal ◽  
2017 ◽  
Vol 38 (2) ◽  
pp. 245-265 ◽  
Author(s):  
Barbara Ghislain ◽  
Bruno Clair
Keyword(s):  
Cell Wall ◽  
Tensile Stress ◽  
Cell Walls ◽  
Tension Wood ◽  
Anatomical Structure ◽  
Wood Fibre ◽  
Tropical Species ◽  
Wood Fibres ◽  
Staining Techniques

Tension wood, a tissue developed by angiosperm trees to actively recover their verticality, has long been defined by the presence of an unlignified cellulosic inner layer in the cell wall of fibres, called the G-layer. Although it was known that some species have no G-layer, the definition was appropriate since it enabled easy detection of tension wood zones using various staining techniques for either cellulose or lignin. For several years now, irrespective of its anatomical structure, tension wood has been defined by its high mechanical internal tensile stress. This definition enables screening of the diversity of cell walls in tension wood fibres. Recent results obtained in tropical species with tension wood with a delay in the lignification of the G-layer opened our eyes to the effective presence of large amounts of lignin in the G-layer of some species. This led us to review older literature mentioning the presence of lignin deposits in the G-layer and give them credit. Advances in the knowledge of tension wood fibres allow us to reconsider some previous classifications of the diversity in the organisation of the fibre walls of the tension wood.

scholarly journals Mechanical characterisation of the developing cell wall layers of tension wood fibres by Atomic Force Microscopy

2021 ◽  
Author(s):  
O. Arnould ◽  
M. Capron ◽  
M. Ramonda ◽  
F. Laurans ◽  
T. Alméras ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Cell Wall ◽  
Tension Wood ◽  
Wall Thickening ◽  
Final Thickness ◽  
Force Microscopy ◽  
Atomic Force ◽  
Wood Fibres ◽  
Key Factor ◽  
Kinetics Of

AbstractTrees can generate large mechanical stresses at the stem periphery to control the orientation of their axes. This key factor in the biomechanical design of trees, named “maturation stress”, occurs in wood fibres during cellular maturation when their secondary cell wall thickens. In this study, the spatial and temporal stiffening kinetics of the different cell wall layers were recorded during fibre maturation on a sample of poplar tension wood using atomic force microscopy. The thickening of the different layers was also recorded. The stiffening of the CML, S1 and S2-layers was initially synchronous with the thickening of the S2 layer and continued a little after the S2-layer reached its final thickness as the G-layer begins to develop. In contrast, the global stiffness of the G-layer, which initially increased with its thickening, was almost stable long before it reached its final maximum thickness. A limited radial gradient of stiffness was observed in the G-layer, but it decreased sharply on the lumen side, where the new sub-layers are deposited during cell wall thickening. Although very similar at the ultrastructural and biochemical levels, the stiffening kinetics of the poplar G-layer appears to be very different from that described in maturing bast fibres.HighlightNew insights into the changes in mechanical properties within the cell wall of poplar tension wood fibres during maturation have been obtained using atomic force microscopy.

Molecular mechanism of AtGA3OX1 and AtGA3OX2 genes affecting secondary wall thickening in stems in Arabidopsis

2013 ◽  
Vol 35 (5) ◽  
pp. 655-665 ◽  
Author(s):  
Zeng-Guang WANG ◽  
Guo-Hua CHAI ◽  
Zhi-Yao WANG ◽  
Xian-Feng TANG ◽  
Chang-Jiang SUN ◽  
...  
Keyword(s):  
Molecular Mechanism ◽  
Secondary Wall ◽  
Wall Thickening ◽  
Secondary Wall Thickening

scholarly journals How Can We Manage Gallbladder Lesions by Transabdominal Ultrasound?

Diagnostics ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 784
Author(s):  
Shinji Okaniwa
Keyword(s):  
High Frequency ◽  
Layer Structure ◽  
Wall Layer ◽  
Pancreaticobiliary Maljunction ◽  
Doppler Imaging ◽  
Wall Thickening ◽  
Contrast Enhanced ◽  
Postural Changes ◽  
Venous Phase

The most important role of ultrasound (US) in the management of gallbladder (GB) lesions is to detect lesions earlier and differentiate them from GB carcinoma (GBC). To avoid overlooking lesions, postural changes and high-frequency transducers with magnified images should be employed. GB lesions are divided into polypoid lesions (GPLs) and wall thickening (GWT). For GPLs, classification into pedunculated and sessile types should be done first. This classification is useful not only for the differential diagnosis but also for the depth diagnosis, as pedunculated carcinomas are confined to the mucosa. Both rapid GB wall blood flow (GWBF) and the irregularity of color signal patterns on Doppler imaging, and heterogeneous enhancement in the venous phase on contrast-enhanced ultrasound (CEUS) suggest GBC. Since GWT occurs in various conditions, subdividing into diffuse and focal forms is important. Unlike diffuse GWT, focal GWT is specific for GB and has a higher incidence of GBC. The discontinuity and irregularity of the innermost hyperechoic layer and irregular or disrupted GB wall layer structure suggest GBC. Rapid GWBF is also useful for the diagnosis of wall-thickened type GBC and pancreaticobiliary maljunction. Detailed B-mode evaluation using high-frequency transducers, combined with Doppler imaging and CEUS, enables a more accurate diagnosis.

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