FINE STRUCTURE OF GUARD-CELL WALLS IN AVENA COLEOPTILE

1957 ◽  
Vol 35 (5) ◽  
pp. 791-793 ◽  
Author(s):  
George Setterfield

not available


Science ◽  
1984 ◽  
Vol 225 (4662) ◽  
pp. 621-623 ◽  
Author(s):  
E. L. SMOOT ◽  
T. N. TAYLOR


CONVERSAZIONES were held this year on 9 May and 27 June. At the first conversazione twenty-seven exhibits and two films were shown. The fine structure of plant roots in relation to transport of nutrient ions and water was demonstrated by Dr D. T. Clarkson of the A.R.C. Letcombe Laboratory, Wantage and Dr A. W. Robards of the Department of Biology, University of York. Two major pathways by which nutrients and water move radially across the cortex towards the central vascular tissue have been distinguished by the use of tracer studies of adsorption by different zones of intact root systems, microautoradiography and electron microscopy. Movement can be apoplastic through cell walls, or symplastic between cells joined by plasmodesmata. As the root ages, structural changes in the endodermis reduce movement in the former pathway but the symplast is not interrupted by the elaboration of endodermal walls because plasmodesmatal connexions remain intact. These observations help explain the contrasting extent to which different ions and water reach the shoot from young and mature parts of root systems.



1976 ◽  
Vol 22 (8) ◽  
pp. 1102-1112 ◽  
Author(s):  
D. H. Ellis ◽  
D. A. Griffiths

Torula thermophila produced typical chlamydospores either as intercalary chains within prostrate hyphae or as terminal swellings on short, lateral, hyphal branches. Mature chlamydospores were spherical, dark brown, smooth-surfaced structures with thick, single-layered cell walls (= secondary wall layer) usually differentiated into an outer electron-dense zone and an inner electron-transparent zone. Disarticulation and spore release occurred after the disintegration of the original hyphal wall.The thallospores of T. thermophila arise in a manner different from the blastospores produced by other species of Torula and are structurally more closely related to the spores produced by Humicola insolens. However until further work has been completed on spore development in the Torulu-Humicola complex of fungi the name T. thermophila is retained.



1966 ◽  
Vol 44 (3) ◽  
pp. 331-340 ◽  
Author(s):  
Shimon Klein ◽  
Yehuda Ben-Shaul

Changes in cell fine structure were studied in axes of green lima bean seeds soaked in water for 1–48 hours. At the beginning of the imbibition period the cortical and pith cells and to a smaller degree the cells of the future conductive tissues contain several vacuoles filled with an amorphous substance. Almost all of the cells contain lipid droplets arranged exclusively along cell walls. The endoplasmic reticulum appears in the form of long tubules, predominantly occupying the peripheral parts of the cell, surrounding the nucleus. A large concentration of ribosomes, mostly unattached, can be found in the cytoplasm. Similar particles make up the bulk of the nucleolus, but could not be found in plastids, which frequently contained starch, but were devoid of internal membranes. Only very few Golgi bodies occur. No changes in fine structure seem to occur during the first 4 hours of imbibition, but after 24 hours the lipid droplets and the vacuolar content have disappeared, the endoplasmic reticulum is more evenly distributed throughout the cells, and a large number of Golgi bodies can be seen.



1972 ◽  
Vol 50 (6) ◽  
pp. 1405-1413 ◽  
Author(s):  
W. G. Allaway ◽  
George Setterfield

Stomata of Vicia faba and Allium porrum were examined in thin section with the electron microscope. Guard cells contained numerous mitochondria, few plastids, and relatively small vacuoles traversed by many strands of cytoplasm. Spherosomes were often observed but were variable in occurrence. Endoplasmic reticulum and dictyosomes were present, although not well developed. Scattered microtubules were present at the periphery of the cells. Microbodies were very rarely observed in guard cells and no plasmodesmata were ever seen in the guard cell walls. Plastids were small and irregular in outline in guard cells of both species. Guard cell plastids of V. faba contained abundant large starch granules. In both species thylakoids were few and grana were small in comparison with mesophyll plastids. The inner of the two bounding membranes of guard cell chloroplasts was extensively invaginated, forming a peripheral reticulum. This was not observed in mesophyll plastids of these species. Small groups of microtubule-like structures were often observed in V. faba guard cell plastids; microtubule-like structures were less frequent in A. porrum plastids, and were not in groups. The structures described are compared with those of other epidermal cells and mesophyll cells, and are discussed in relation to guard cell physiology.



1965 ◽  
Vol 43 (3) ◽  
pp. 339-343
Author(s):  
J. Ross Colvin

A small fraction of individual cellulose microfibrils in plant cell walls show appreciable bending along a portion of their length in a plane tangential to the cell surface. Segments of such curved microfibrils from transverse sections of Avena coleoptile epidermal or parenchyma cells do not straighten when they are freed from the constraints imposed by adjacent microfibrils, amorphous cell wall constituents, or the embedding medium. The curvature of these segments is not affected by immersion in cold water for 30 minutes, in hot water for 10 minutes, or in steam at 100° for 10 minutes. The results indicate that there is no elastic deformation of bent cellulose microfibrils in dried plant cell walls. The curvature of the microfibrils in the absence of elastic deformation suggests either (a) that cellulose microfibrils may be synthesized in a bent strain-free condition or (b) that cellulose microfibrils are synthesized in a straight form, followed by elastic deformation with subsequent release of strain by recrystallization on drying.



Planta ◽  
1965 ◽  
Vol 66 (2) ◽  
pp. 126-134 ◽  
Author(s):  
Alfred C. Olson ◽  
James Bonner ◽  
D. James Morr�






2003 ◽  
Vol 67 (18) ◽  
pp. 3299-3311 ◽  
Author(s):  
M.I. Boyanov ◽  
S.D. Kelly ◽  
K.M. Kemner ◽  
B.A. Bunker ◽  
J.B. Fein ◽  
...  


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