The nature of surface growth in plant cells

1956 ◽  
Vol 4 (3) ◽  
pp. 193 ◽  
Author(s):  
AB Wardrop

Autoradiographs have been prepared from parenchyma isolated from Avena coleoptile segments grown in a medium containing labelled glucose. The autoradiographs show that there is no concentration of radioactive material at the cell tips and labelled cellulose appears to be uniformly distributed in the cell wall. Electron micrographs of similar material show that the cellulose microfibrils are almost transversely oriented on the inner surface of the cell wall but are considerably dispersed from this direction on the outer surface. From this evidence it is concluded that growth in coleoptile parenchyma is not of the "bipolar" or "mosaic" types previously suggested, but corresponds to the "multi-net growth" of Roelofsen and Houwink. In addition a study has been made of the relation of microfibril orientation to cell form in parenchyma of onion root and in roots after treatment with colchicine, from which it is concluded that the final microfibril orientation on the outer wall surface is determined by the extent and polarity of its surface growth.

1957 ◽  
Vol 3 (2) ◽  
pp. 171-182 ◽  
Author(s):  
S. T. Bayley ◽  
J. R. Colvin ◽  
F. P. Cooper ◽  
Cecily A. Martin-Smith

The primary walls of epidermal cells in Avena coleoptiles ranging in length from 2 to 40 mm. have been studied in the electron and polarizing microscopes and by the low-angle scattering of x-rays. The outer walls of these cells are composed of multiple layers of cellulose microfibrils oriented longitudinally; initially the number of layers is between 10 and 15 but this increases to about 25 in older tissue. Where epidermal cells touch, these multiple layers fuse gradually into a primary wall of the normal type between cells. In these radial walls, the microfibrils are oriented transversely. Possible mechanisms for the growth of the multilayered outer wall during cell elongation are discussed.


1969 ◽  
Vol 17 (2) ◽  
pp. 229 ◽  
Author(s):  
AB Wardrop

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.


Holzforschung ◽  
2000 ◽  
Vol 54 (5) ◽  
pp. 469-473 ◽  
Author(s):  
Masato Yoshida ◽  
Yoshihiro Hosoo ◽  
Takashi Okuyama

Summary Field emission scanning electron microscopy and energy-dispersive X-ray microanalysis were used to investigate the generation of growth stress in connection with the deposition of cell wall materials along the innermost surface of radial walls during secondary wall formation of differentiating tracheids of Cryptomeria japonica. Samples were collected when the turgor pressure of the tree was low (16:00 h), and when the pressure was high (6:00 h). In samples collected at 16:00 h, cellulose microfibrils deposited on the innermost surface of radial walls were clearly evident and amorphous material was rarely found. Conversely, in samples collected at 6:00 h, cellulose microfibrils were rarely observed and the amorphous material was prevalent. Cellulose microfibrils were evident, however, after removing the amorphous material with chlorite. The concentration of potassium on the inner surface of radial walls was greater at 6:00 h than at 16:00 h. After chlorite treatment, the concentration of potassium measured in the samples collected at 6:00 h decreased to a level equivalent to that in samples collected at 16:00 h and thus potassium was found to be associated with the amorphous material on the cellulose microfibrils. The amorphous material is probably a matrix of hemicellulose and monolignol, material that is abundant on the inner surface of developing cell walls, especially during expansion (as a result of high turgor pressure) of differentiating tracheids. A matrix of hemicellulose and lignin deposited in the expanded gaps between cellulose microfibrils and daily expansion of the gaps probably produces an isotropic compressive stress (growth stress). This paper demonstrates periodicity in cell wall formation as a result of the cycles of compressive growth in the differentiating cell wall.


1963 ◽  
Vol 19 (1) ◽  
pp. 239-250 ◽  
Author(s):  
M. C. Ledbetter ◽  
K. R. Porter

This paper reports an electron microscope examination of the cortices of some plant cells engaged in wall formation. Previous studies of similar material fixed in OSO4 alone have disclosed discontinuities in the plasma membrane and other evidence of inadequate fixation. After glutaraldehyde, used as a fixative in this present study, the general preservation of cortical fine structure is greatly improved. This is shown, for example, by the first evidence of slender tubules, 230 to 270 A in diameter and of indeterminate length, in plant cells of this type. They have been found in the cortical regions of cells of two angiosperms and one gymnosperm, representing all the material so far studied following this method of fixation. The tubules are identical in morphology to those also observed here in the mitotic spindles of plant cells, except that the latter have a somewhat smaller diameter. It is noted that the cortical tubules are in a favored position to govern cytoplasmic streaming and to exert an influence over the disposition of cell wall materials. In this regard it may be of some significance that the tubules just beneath the surface of the protoplast mirror the orientation of the cellulose microfibrils of the adjacent cell walls.


1967 ◽  
Vol 35 (3) ◽  
pp. 659-674 ◽  
Author(s):  
Peter M. Ray

Segments cut from growing oat coleoptiles and pea stems were fed glucose-3H in presence and absence of the growth hormone indoleacetic acid (IAA). By means of electron microscope radioautography it was demonstrated that new cell wall material is deposited both at the wall surface (apposition) and within the preexisting wall structure (internally). Quantitative profiles for the distribution of incorporation with position through the thickness of the wall were obtained for the thick outer wall of epidermal cells. With both oat coleoptile and pea stem epidermal outer walls, it was found that a larger proportion of the newly synthesized wall material appeared to become incorporated within the wall in the presence of IAA. Extraction experiments on coleoptile tissue showed that activity that had been incorporated into the cell wall interior represented noncellulosic constituents, mainly hemicelluloses, whereas cellulose was deposited largely or entirely by apposition. It seems possible that internal incorporation of hemicelluloses plays a role in the cell wall expansion process that is involved in cell growth.


1993 ◽  
Vol 3 (5) ◽  
pp. 637-646 ◽  
Author(s):  
Jian-Kang Zhu ◽  
Jun Shi ◽  
Utpal Singh ◽  
Sarah E. Wyatt ◽  
Ray A. Bressan ◽  
...  

1959 ◽  
Vol 12 (4) ◽  
pp. 395 ◽  
Author(s):  
J Dainty ◽  
AB Hope

Measurements of ion exchange were made between isolated cell walls of Ohara australis and an external solution. Comparison between intact cells and cell walls showed that nearly all the easily exchangeable cations are located in the cell wall. The wall is hown to consist of "water free space" (W.F.S.) and "Donnan free space" (D.F.S.); the concentration of in diffusible anions in the D.F.S. is about O� 6 equivjl. This finding is contrary to past suggestions that the D.F.S. is in the cytoplasm of plant cells.


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