The Nature of Reaction Wood II. The Cell Wall Organization of Compression Wood Tracheids

Optical and X-ray methQds have been used in the examinatiQn Qf the secQndarycell wall Qf cQmpressiQn WQQd tracheids from a number Qf species QfgymnDsperms.By these methQds it has been shQwn that the cell wall Qf CQmpressiQn WQQd tracheidscDnsists Qf two. layers. In the Quter layer the micelles are inclined at a large angle 'to. the lQngitudinal axis Qf the tracheid, while in the inner layer the micelles areinclined at a relatively smaller angle. In the inner Df the two. layers there exist radialdiscQntinuities in the spiral micellar structure, which are visible as IQngitudinal striatiQnsin the cell wall. These discQntinuities also. aCCQunt for the radial distributiQn Qflignin which is observed in transverse sectiQns Qf cQmpressiQn WQQd tracheids. Bydetermining the average tracheid length Qf the last-fDrmed late WQod in the variQusgrowth rings Df several eccentric stems Qf Pinus radiata D.DQn it has been shDwn thatthe tracheids Qf cQmpressiQn WQQd are appreciably shQrter than WQuld be the case ifno. cQmpressiQn WQQd were present. A study Qf the change in micellar QrientatiQn withchange in tracheid length has indicated that the angle Qf micellar QrientatiQn in CQmpressiQnWQQd tracheids dQes nQt differ signific(mtly frQm that existing in nQrmalWQQd tracheids Qf similar length. In so. far as the prQperties Qf WQQd are determinedby cell wall QrganizatiQn, it is cQncluded that cQmparisQns between cQmpressiQn WQDdand normal WQQd shQuld be made Qn material Qf the same tracheid length and spiralQrganizatiDn. It is suggested that bQth the reductiQn in tracheid length and eccentricradial growth in stems cQntaining cQmpressiQn WQQd are to. be attributed to. an increasein the number Df bDth transverse and tangential lQngitudinal divisiQns Qf thefusifQrm initials Qf the cambium.

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The Nature of Reaction Wood III. Cell Division and Cell Wall Formation in Conifer Stems

Australian Journal of Biological Sciences ◽

10.1071/bi9520385 ◽

1952 ◽

Vol 5 (4) ◽

pp. 385 ◽

Cited By ~ 12

Author(s):

ABW Ardrop ◽

HE Dadswell

Keyword(s):

Cell Wall ◽

Cell Division ◽

Secondary Wall ◽

Compression Wood ◽

Normal Wood ◽

Reaction Wood ◽

Primary Wall ◽

Wall Formation ◽

Tracheid Length ◽

Secondary Wall Formation

Cell division, the nature of extra-cambial readjustment, and the development of the secondary wall in the tracheids of conifer stems have been investigated in both compression wood and normal wood. It has been shown that the reduction in tracheid length, accompanying the development of compression wood and, in normal wood, increased radial growth after suppression, result from an increase in the number of anticlinal divisions in the cambium. From observations of bifurcated and otherwise distorted cell tips in mature tracheids, of small but distinct terminal canals connecting the lumen to the primary wall in the tips of mature tracheids, and of the presence of only primary wall at the tips of partly differentiated tracheids, and from the failure to observe remnants of the parent primary walls at the ends of differentiating tracheids, it has been concluded that extra-cambial readjustment of developing cells proceeds by tip or intrusive growth. It has been further concluded that the development of the secondary wall is progressive towards the cell tips, on the bases of direct observation of secondary wall formation in developing tracheids and of the increase found in the number of turns of the micellar helix per cell with increasing cell length. The significance of this in relation to the submicroscopic organization of the cell wall has been discussed. Results of X-ray examinations and of measurements of� tracheid length in successive narrow tangential zones from the cambium into the xylem have indicated that secondary wall formation begins before the dimensional changes of differentiation are complete.

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

Australian Journal of Botany ◽

10.1071/bt9550177 ◽

1955 ◽

Vol 3 (2) ◽

pp. 177 ◽

Cited By ~ 53

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.

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The nature of reaction wood. VIII. The structure and differentiation of compression wood

Australian Journal of Botany ◽

10.1071/bt9640024 ◽

1964 ◽

Vol 12 (1) ◽

pp. 24 ◽

Cited By ~ 49

Author(s):

AB Wardrop ◽

GW Davies

Keyword(s):

Compression Wood ◽

Early Stage ◽

Wood Formation ◽

Ground Substance ◽

Reaction Wood ◽

Intercellular Spaces ◽

Chemically Induced ◽

Cell Wall Organization ◽

Cytoplasmic Organization ◽

Cytoplasmic Ground Substance

The cell wall organization of tracheids of natural and chemically induced compression wood of Pinus radiata and Actinostrobus pyramidalis has been shown to be the same, and is similar to that established in previous studies of natural compression wood. In the secondary wall only two layers were present. In the second of these there was a well-developed system of helical cavities, separating ribs of cellulose. The ribs of cellulose were parallel to the direction of microfibril orientation; were complex in form; and the cellulose lamellae lay parallel with the wall surface. A well-developed wart structure was present. During the differentiation of compression wood tracheids, the intercellular spaces were formed during the phase of surface enlargement of the differentiating tracheids. At an early stage the intercellular spaces appeared to contain cytoplasmic ground substance. During the development of the layer S1 the cytoplasmic organization was similar to that of normal tracheids, the cells containing a large vacuole with a well-developed tonoplast and plasmalemma. During the development of the layer S2 the cytoplasm contained numerous small vesicles with no large vacuoles, and in many instances the plasmalemma was absent. At the conclusion of the differentiation of the cell the plasmalemma was again present and penetrated the helical cavities of the wall. Compression wood induced by 3-indoleacetic acid (IAA) alone, gibberellic acid (GA) alone, or IAA and GA in combination was identical with that formed under natural conditions. The localized lateral application of IAA to vertical stems caused conspicuous bending of the stem as well as compression wood formation.

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Lignin distribution in mild compression wood of Pinus radiata

Canadian Journal of Botany ◽

10.1139/b98-190 ◽

1999 ◽

Vol 77 (1) ◽

pp. 41-50 ◽

Cited By ~ 12

Author(s):

Lloyd A Donaldson ◽

Adya P Singh ◽

Arata Yoshinaga ◽

Keiji Takabe

Keyword(s):

Cell Wall ◽

Fluorescence Microscopy ◽

Pinus Radiata ◽

Compression Wood ◽

Middle Lamella ◽

Confocal Fluorescence Microscopy ◽

Interference Microscopy ◽

Normal Wood ◽

Lignin Distribution ◽

Confocal Fluorescence

Lignin distribution in the tracheid cell wall of mild compression wood in Pinus radiata D. Don was examined by interference microscopy, confocal fluorescence microscopy, and ultraviolet (UV) microscopy. Two anatomically different samples of mild compression wood were compared with a sample of normal wood using quantitative interference microscopy and microdensitometry combined with confocal fluorescence microscopy to estimate the quantitative or semiquantitative lignin distribution in the S2 and S2L regions of the secondary cell wall and of the cell corner middle lamella (CCML). One of these samples was briefly examined by UV microscopy for comparison. Quantitative interference microscopy provided information on lignin concentration in different regions of the cell wall with values of 26, 46, and 57%, respectively, for the S2, S2L, and CCML regions of sample 1 and 20, 29, and 46%, respectively, for the same regions of sample 2. Microdensitometry of confocal fluorescence images provided semiquantitative information on the relative lignin distribution based on lignin autofluorescence. Comparison between the two compression wood samples using autofluorescence gave results that were in partial agreement with interference microscopy with respect to the relative lignification levels in the S2, S2L, and CCML regions. Some improvement was achieved by using calibration values for hemicellulose rather than holocellulose for interference data in the S2L region. Results for UV microscopy performed on sample 1 indicated that the lignification of the CCML region was comparable with that of the S2L region in this sample but with some variation among cells. All three techniques indicated significant variation in lignification levels of the S2L and CCML regions among adjacent cells and a significant reduction in the lignification of the CCML region compared to normal wood.Key words: lignin distribution, interference microscopy; confocal fluorescence microscopy, UV microscopy, mild compression wood, Pinus radiata D. Don.

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Critical review on the mechanisms of maturation stress generation in trees

Journal of The Royal Society Interface ◽

10.1098/rsif.2016.0550 ◽

2016 ◽

Vol 13 (122) ◽

pp. 20160550 ◽

Cited By ~ 30

Author(s):

Tancrède Alméras ◽

Bruno Clair

Keyword(s):

Cell Wall ◽

Tension Wood ◽

Compression Wood ◽

Current Knowledge ◽

Stress Generation ◽

Plant Science ◽

Reaction Wood ◽

Wood Structure ◽

Structure State ◽

Cell Organization

Trees control their posture by generating asymmetric mechanical stress around the periphery of the trunk or branches. This stress is produced in wood during the maturation of the cell wall. When the need for reaction is high, it is accompanied by strong changes in cell organization and composition called reaction wood, namely compression wood in gymnosperms and tension wood in angiosperms. The process by which stress is generated in the cell wall during its formation is not yet known, and various hypothetical mechanisms have been proposed in the literature. Here we aim at discriminating between these models. First, we summarize current knowledge about reaction wood structure, state and behaviour relevant to the understanding of maturation stress generation. Then, the mechanisms proposed in the literature are listed and discussed in order to identify which can be rejected based on their inconsistency with current knowledge at the frontier between plant science and mechanical engineering.

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Histochemistry of reaction wood differentiation in Pinus radiata D. Don

Australian Journal of Botany ◽

10.1071/bt9670377 ◽

1967 ◽

Vol 15 (3) ◽

pp. 377 ◽

Cited By ~ 10

Author(s):

G Scurfield

Keyword(s):

Pinus Radiata ◽

Cell Walls ◽

Compression Wood ◽

Reaction Wood ◽

Chemical Changes ◽

Wood Compression ◽

Histochemical Tests

Histochemical tests have been applied to a study of the differentiation of the cell walls in reaction wood (compression wood) formed in the stems of horizontally grown seedlings of Pinus radiata. The results are discussed on the basis of the chemical specificity of the tests and the information they provide as to the chemical changes which occur in the cell walls.

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An Electron Microscopic Investigation of the Cell Wall Organization of Conifer Tracheids and Conifer Cambium

Australian Journal of Biological Sciences ◽

10.1071/bi9500265 ◽

1950 ◽

Vol 3 (3) ◽

pp. 265 ◽

Cited By ~ 6

Author(s):

AJ Hodge ◽

AB Wardrop

Keyword(s):

Cell Wall ◽

Microscopic Investigation ◽

Electron Microscopic Investigation ◽

Electron Micrograph ◽

Electron Microscopic ◽

X Ray ◽

Inner Surface ◽

Cell Wall Organization ◽

Optical Evidence

An electron micrograph of a replica of the inner surface of the secondarycell wall of a conifer tracheid, demonstrating the almost transverse orientationof the microfibrils in this layer, is presented. This evidence provides confirmationof the type of cell wall organization of conifer tracheids proposed inother investigations on the basis of X-ray and optical evidence and of microscopicexamination. The existence of fibrils of 50-100 A in diameter has beendemonstrated in cell wall fragments obtained by the disintegration of cambiuminitials and of conifer tracheids. It is suggested that these microfibrilsmay correspond to the "micelles" or "crystalline regions" inferred from X-rayexamination.

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Compression Wood does not Form in the Roots of Pinus Radiata

IAWA Journal ◽

10.1163/22941932-90000136 ◽

2006 ◽

Vol 27 (1) ◽

pp. 45-54 ◽

Cited By ~ 2

Author(s):

Linda C.Y. Hsu ◽

John C.F. Walker ◽

Brian G. Butterfield ◽

Sandra L. Jackson

Keyword(s):

Mechanical Stress ◽

Pinus Radiata ◽

Compression Wood ◽

Lateral Roots ◽

Compressive Load ◽

Radiata Pine ◽

Wood Formation ◽

Wall Layer ◽

Reaction Wood ◽

Wood Compression

We investigated the potential for the roots of Pinus radiata D. Don to form compression wood. Compression wood was not observed in either the tap or any lateral roots further than 300 mm from the base of the stem. This suggests that either the roots do not experience the stresses required to induce compression wood formation, or that they lack the ability to form it. Roots artificially subjected to mechanical stress also failed to develop compression wood. It is therefore unlikely that an absence of a compressive load on buried roots can account for the lack of compression wood. Application of auxin to the cambia of lateral roots was similarly ineffective at inducing the formation of compression wood. These observations suggest that the buried roots of radiata pine lack the ability to develop compression wood. We also report the formation of an atypical S3 wall layer in the mechanically-stressed and auxin-treated tracheids and suggest that a reaction wood that is different to compression wood may well form in roots.

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Cell Wall Organization and the Properties of the Xylem 1. Cell Wall Organization and the Variation of Breaking Load in Tension of the Xylem in Conifer Stems

Australian Journal of Biological Sciences ◽

10.1071/bi9510391 ◽

1951 ◽

Vol 4 (4) ◽

pp. 391 ◽

Cited By ~ 9

Author(s):

ABW Ardrop

Keyword(s):

Cell Wall ◽

Basic Density ◽

Breaking Load ◽

Cellulose Content ◽

Micellar System ◽

Growth Rings ◽

Cell Axis ◽

Tracheid Length ◽

Cell Wall Organization ◽

Longitudinal Cell

The variation of breaking load in tension of tangential longitudinal sections of wood, taken from successive growth rings of each of six conifer stems, has been studied. An increase in this property was observed in successive growth rings from the stem centre of each specimen. This was paralleled by an increase in tracheid length, basic density, and cellulose content. The inclination to the longitudinal cell axis of the spiral micellar system of the cell wall decreased with increasing tracheid length.

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