The opening and shedding mechanism of the female cones of Pinus radiata

1964 ◽  
Vol 12 (2) ◽  
pp. 125 ◽  
Author(s):  
R Allen ◽  
AB Wardrop
Keyword(s):  
Pinus Radiata ◽  
Radial Growth ◽  
Secondary Wall ◽  
Vascular Tissue ◽  
Middle Layer ◽  
Cell Axis ◽  
Vascular Connection ◽  
Differential Shrinkage ◽  
Longitudinal Cell ◽  
Cone Scale

The opening of the female cones of P. radiata has been shown to result from differential shrinkage between the adaxial vascular tissue and the abaxial sclerenchyma of the cone scale. The organization of the secondary wall of the tracheids typically consists of three helically organized concentric layers. In the outer and inner layers the microfibrillar orientation is approximately transverse, and in the middle layer the helix makes an angle of c. 40° with the longitudinal cell axis. In the sclerenchyma the secondary wall consists of wide layers in which the microfibrils of the lamellae are almost transverse to the longitudinal cell axis, alternating with narrow layers in which the microfibrils of the lamellae are almost parallel to the cell axis. Opening is preceded by a severance of the vascular connection between the cone and the stem or branch by the occlusion of the lurnina of the tracheids of the peduncle with resin. As radial growth of the stem proceeds, small fissures develop between the xylem of the stem or branch and that of the cone peduncle. The fissures become filled with resin and there is a progressive erosion of the tracheids of the peduncle until ultimately the xylem of the peduncle is separated from that of the stem or branch.

Review — The Orientation of Cellulose Microfibrils in the cell walls of Tracheids in Conifers

IAWA Journal ◽  
2005 ◽  
Vol 26 (2) ◽  
pp. 161-174 ◽  
Author(s):  
Hisashi Abe ◽  
Ryo Funada
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Outer Layer ◽  
Cell Walls ◽  
Secondary Wall ◽  
Middle Layer ◽  
Cellulose Microfibrils ◽  
Conifer Species ◽  
Predominant Orientation ◽  
Scanning Electron

We examined the orientation of cellulose microfibrils (Mfs) in the cell walls of tracheids in some conifer species by field emission-scanning electron microscopy (FE-SEM) and developed a model on the basis of our observations. Mfs depositing on the primary walls in differentiating tracheids were not well-ordered. The predominant orientation of the Mfs changed from longitudinal to transverse, as the differentiation of tracheids proceeded. The first Mfs to be deposited in the outer layer of the secondary wall (S1 layer) were arranged as an S-helix. Then the orientation of Mfs changed gradually, with rotation in the clockwise direction as viewed from the lumen side of tracheids, from the outermost to the innermost S1 layer. Mfs in the middle layer of the secondary wall (S2 layer) were oriented in a steep Z-helix with a deviation of less than 15° within the layer. The orientation of Mfs in the inner layer of the secondary wall (S3 layer) changed, with rotation in a counterclockwise direction as viewed from the lumen side, from the outermost to the innermost S3 layer. The angle of orientation of Mfs that were deposited on the innermost S3 layer varied among tracheids from 40° in a Z-helix to 20° in an S-helix.

scholarly journals The Cell Wall Structure of Xylem Parenchyma

1952 ◽  
Vol 5 (2) ◽  
pp. 223 ◽  
Author(s):  
AB Wardrop ◽  
HE Dadswell
Keyword(s):  
Cell Wall ◽  
Fine Structure ◽  
Secondary Cell Wall ◽  
Primary Cell Wall ◽  
Wall Structure ◽  
Xylem Parenchyma ◽  
Cell Axis ◽  
X Ray ◽  
Ray Methods ◽  
Longitudinal Cell

The fine structure of the cell wall of both ray and vertical parenchyma has been investigated. In all species examined secondary thickening had occurred. In the primary cell wall the micellar orientation was approximately trans"erse to the longitudiJ)aI cell axis. Using optical and X-ray methods the secondary cell wall was shown to possess a helical micellar organization, the micelles being inclined between 30� and 60� to the longitudinal cell axis.

Nanostructural assembly of cellulose, hemicellulose, and lignin in the middle layer of secondary wall of ginkgo tracheid

2009 ◽  
Vol 55 (6) ◽  
pp. 409-416 ◽  
Author(s):  
Noritsugu Terashima ◽  
Kohei Kitano ◽  
Miho Kojima ◽  
Masato Yoshida ◽  
Hiroyuki Yamamoto ◽  
...  
Keyword(s):  
Secondary Wall ◽  
Middle Layer

scholarly journals Mapping thermal conductivity across bamboo cell walls with scanning thermal microscopy

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Darshil U. Shah ◽  
Johannes Konnerth ◽  
Michael H. Ramage ◽  
Claudia Gusenbauer
Keyword(s):  
Thermal Conductivity ◽  
Cell Walls ◽  
Vascular Tissue ◽  
Thin Layers ◽  
Cellulose Microfibrils ◽  
Natural Material ◽  
Scanning Thermal Microscopy ◽  
Cell Axis ◽  
Thermal Microscopy ◽  
Fibre Cell

Abstract Scanning thermal microscopy is a powerful tool for investigating biological materials and structures like bamboo and its cell walls. Alongside nanoscale topographical information, the technique reveals local variations in thermal conductivity of this elegant natural material. We observe that at the tissue scale, fibre cells in the scattered vascular tissue would offer preferential pathways for heat transport due to their higher conductivities in both anatomical directions, in comparison to parenchymatic cells in ground tissue. In addition, the transverse orientation offers more resistance to heat flow. Furthermore, we observe each fibre cell to compose of up to ten layers, with alternating thick and thin lamellae in the secondary wall. Notably, we find the thin lamellae to have relatively lower conductivity than the thick lamellae in the fibre direction. This is due to the distinct orientation of cellulose microfibrils within the cell wall layers, and that cellulose microfibrils are highly anisotropic and have higher conductivity along their lengths. Microfibrils in the thick lamellae are oriented almost parallel to the fibre cell axis, while microfibrils in the thin lamellae are oriented almost perpendicular to the cell axis. Bamboo grasses have evolved to rapidly deposit this combination of thick and thin layers, like a polymer composite laminate or cross-laminated timber, for combination of axial and transverse stiffness and strength. However, this architecture is found to have interesting implications on thermal transport in bamboo, which is relevant for the application of engineered bamboo in buildings. We further conclude that scanning thermal microscopy may be a useful technique in plant science research, including for phenotyping studies.

Ovule and seed development in Pinus radiata: postmeiotic development, fertilization, and embryogeny

1976 ◽  
Vol 54 (18) ◽  
pp. 2141-2154 ◽  
Author(s):  
Barbara S. Lill
Keyword(s):  
Seed Development ◽  
Pinus Radiata ◽  
Vascular Tissue ◽  
Small Cells ◽  
Dense Cytoplasm ◽  
Procambial Strand ◽  
Embryo Maturity

Development of ovule tissues in Pinus radiata after meiosis, fertilization, and embryogeny is comparable with that of other pines, but P. radiata takes longer to develop. Fertilization occurs 15 months after pollination and morphological embryo maturity is reached 5 months later. In ovules harvested in spring after meiosis, a curved band of small cells with dense cytoplasm extends from the chalazal end of the ovule to the vascular tissue of the ovuliferous scale. It is interpreted as a procambial strand, which in the next year, differentiates basipetally into elongated, thick-walled cells with degenerated nuclei.

The structure of the cell wall in lignifield collenchyma of Eryngium sp. (Umbelliferae)

1969 ◽  
Vol 17 (2) ◽  
pp. 229 ◽  
Author(s):  
AB Wardrop
Keyword(s):  
Cell Wall ◽  
Cell Division ◽  
Cell Differentiation ◽  
Secondary Wall ◽  
Indoleacetic Acid ◽  
Cellulose Microfibrils ◽  
Cell Axis ◽  
Wall Formation ◽  
Microfibril Orientation ◽  
Secondary Wall Formation

In Eryngium vesiculosum and E. rostratum, the leaf collenchyma is characterized by the development of a lignified secondary wall in the final stages of cell differentiation. The collenchyma wall is rich in pectic substances which are distributed uniformly. In the outer limiting region of the collenchyma wall the microfibril orientation is random and this structure is considered to be the wall formed at cell division. The collenchyma wall consists of six to eight layers in which the microfibrils are alternately transversely and longitudinally oriented. Each layer consists of a number of lamellae of microfibrils. In the secondary lignified wall the cellulose microfibrils are arranged helically, the direction of their orientation making an angle of 40-45° to the cell axis. Excised leaf segments showed greatest elongation in solutions of glucose and 3-indoleacetic acid, when the collenchyma walls were thin, and no elongation occurred in segments in which secondary wall formation had commenced. In radial sections layers of transversely oriented microfibrils could not be seen distant from the lumen although discontinuities in wall texture were apparent. Layers of transversely oriented microfibrils could be seen adjacent to the lumen. It is suggested that reorientation of layers of initially transversely oriented microfibrils takes place during elongation of the cells.

Phenology and radial stem growth periodicity in evergreen subtropical rainforest trees

IAWA Journal ◽  
2010 ◽  
Vol 31 (3) ◽  
pp. 293-307 ◽  
Author(s):  
Laura Yáñez-Espinosa ◽  
Teresa Terrazas ◽  
Lauro López-Mata
Keyword(s):  
Radial Growth ◽  
Vascular Tissue ◽  
Stem Growth ◽  
Tissue Differentiation ◽  
Vascular Cambium ◽  
Evergreen Species ◽  
Leaf Initiation ◽  
Close Relationship ◽  
Cambium Activity ◽  
Phenological Event

A close relationship between leafing, flowering, fruiting and radial growth has been conjectured to occur in tropical and subtropical rainforest trees. Radial stem growth, in particular, has been associated with the activity of the two secondary meristems, the vascular cambium and, to a lesser degree, the phellogen. In tropical trees vascular cambium activity may occur either virtually year-round, or it may be restricted to a short season. Phellogen and vascular cambium activities may or may not correspond to each other. In subtropical environments, even evergreens may demonstrate seasonal phenology in leaf initiation, flowering and seed set. In the present study, phenological events were analyzed in the evergreen species Aphananthe monoica, Pleuranthodendron lindenii and Psychotria costivenia. A correlation analysis showed that more than half of the variation is shared by phenological event variables (leafing, flowering and fruiting) and radial growth variables (vascular cambium and phellogen activity, and vascular tissue differentiation). Leaf initiation, flowering and vascular cambium activation were the most closely-related simultaneous events during the summer; whereas fruiting, phellogen activity and vascular tissue differentiation were the most closely-related simultaneous events during the summer and fall. This could explain why the leaf initiation and expansion stages, which produce growth regulators, are directly involved in radial growth.

scholarly journals Escherichia coliDnaA forms helical structures along the longitudinal cell axis distinct from MreB filaments

2009 ◽  
Vol 72 (3) ◽  
pp. 645-657 ◽  
Author(s):  
Kelly Boeneman ◽  
Solveig Fossum ◽  
Yanhua Yang ◽  
Nicholas Fingland ◽  
Kirsten Skarstad ◽  
...  
Keyword(s):  
Helical Structures ◽  
Cell Axis ◽  
Longitudinal Cell

True dichotomies in seedlings of Pinus radiata

1976 ◽  
Vol 54 (9) ◽  
pp. 1020-1022
Author(s):  
Richard T. Riding
Keyword(s):  
Shoot Apex ◽  
Pinus Radiata ◽  
Vascular Tissue

Histological observations of bifurcating seedlings of Pinus radiata revealed that this phenomenon resulted from a dichotomy of the shoot apex into two meristems. Vascular tissue passed equally into the two branches of the dichotomy.

Localization of actin filaments and cortical microtubules in wood-forming tissues of conifers

IAWA Journal ◽  
2019 ◽  
Vol 40 (4) ◽  
pp. 703-720 ◽  
Author(s):  
Shahanara Begum ◽  
Osamu Furusawa ◽  
Masaki Shibagaki ◽  
Satoshi Nakaba ◽  
Yusuke Yamagishi ◽  
...  
Keyword(s):  
Final Stage ◽  
Actin Filaments ◽  
Secondary Wall ◽  
Cortical Microtubules ◽  
Cell Axis ◽  
Wall Formation ◽  
Bordered Pits ◽  
Secondary Wall Formation ◽  
Cambial Cells ◽  
Helical Thickenings

ABSTRACT The aim of the present study was to investigate the orientation and localization of actin filaments and cortical microtubules in wood-forming tissues in conifers to understand wood formation. Small blocks were collected from the main stems of Abies firma, Pinus densiflora, and Taxus cuspidata during active seasons of the cambium. Bundles of actin filaments were oriented axially or longitudinally relative to the cell axis in fusiform and ray cambial cells. In differentiating tracheids, actin filaments were oriented longitudinally relative to the cell axis during primary and secondary wall formation. In contrast, the orientation of well-ordered cortical microtubules in tracheids changed from transverse to longitudinal during secondary wall formation. There was no clear relationship between the orientation of actin filaments and cortical microtubules in cambial cells and cambial derivatives. Aggregates of actin filaments and a circular band of cortical microtubules were localized around bordered pits and cross-field pits in differentiating tracheids. In addition, rope-like bands of actin filaments were observed during the formation of helical thickenings at the final stage of formation of secondary walls in tracheids. Actin filaments might not play a major role in changes in the orientation of cortical microtubules in wood-forming tissues. However, since actin filaments were co-localized with cortical microtubules during the formation of bordered pits, cross-field pits and helical thickenings at the final stage of formation of the secondary wall in tracheids, it seems plausible that actin filaments might be closely related to the localization of cortical microtubules during the development of these modifications of wood structure.

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