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  • 1
    Electronic Resource
    Electronic Resource
    Ultrastructure of and plasmodesmatal frequency in mature leaves of sugarcane (1991)
    Springer
    Planta 184 (1991), S. 291-306 
    Details
    ISSN: 1432-2048
    Keywords: C4 plant ; Leaf ultrastucture ; Mestome ; sheath ; Phloem loading ; Plasmodesma ; Saccharum (plasmodesmata) ; Vascular bundle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Vascular bundles and contiguous tissues of leaf blades of sugarcane (Saccharum interspecific hybrid L62–96) were examined with light and transmission electron microscopes to determine their cellular composition and the frequency of plasmodesmata between the various cell combinations. The large vascular bundles typically are surrounded by two bundle sheaths, an outer chlorenchymatous bundle sheath and an inner mestome sheath. In addition to a chlorenchymatous bundle sheath, a partial mestome sheath borders the phloem of the intermediate vascular bundles, and at least some mestome-sheath cells border the phloem of the small vascular bundles. Both the walls of the chlorenchymatous bundlesheath cells and of the mestome-sheath cells possess suberin lamellae. The phloem of all small and intermediate vascular bundles contains both thick- and thin-walled sieve tubes. Only the thin-walled sieve tubes have companion cells, with which they are united symplastically by pore-plasmodesmata connections. Plasmodesmata are abundant at the Kranz mesophyll-cell-bundlesheath-cell interface associated with all sized bundles. Plasmodesmata are also abundant at the bundle-sheathcell-vascular-parenchyma-cell, vascular-parenchyma-cellvascular-parenchyma-cell, and mestome-sheath-cell-vascular-parenchyma-cell interfaces in small and intermediate bundles. The thin-walled sieve tubes and companion cells of the large vascular bundles are symplastically isolated from all other cell types of the leaf. The same condition is essentially present in the sieve-tube-companion-cell complexes of the small and intermediate vascular bundles. Although few plasmodesmata connect either the thin-walled sieve tubes or their companion cells to the mestome sheath of small and intermediate bundles, plasmodesmata are somewhat more numerous between the companion cells and vascular-parenchyma cells. The thick-walled sieve tubes are united with vascular-parenchyma cells by pore-plasmodesmata connections. The vascular-parenchyma cells, in turn, have numerous plasmodesmatal connections with the bundle-sheath cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00195330
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  • 2
    Electronic Resource
    Electronic Resource
    Fine structure of plasmodesmata in mature leaves of sugarcane (1991)
    Springer
    Planta 184 (1991), S. 307-318 
    Details
    ISSN: 1432-2048
    Keywords: C4 plant ; Intercellular communication ; Phloem ; Plasmodesma ; Saccharum (plasmodesmata) ; Vascular bundle ; Xylem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The fine structure of plasmodesmata in vascular bundles and contiguous tissues of mature leaf blades of sugarcane (Saccharum interspecific hybrid L62–96) was studied with the transmission electron microscope. Tissues were fixed in glutaraldehyde, with and without the addition of tannic acid, and postfixed in OsO4. The results indicate that the fine structure of plasmodesmata in sugarcane differs among various cell combinations in a cell-specific manner, but that three basic structural variations can be recognized among plasmodesmata in the mature leaf: 1) Plasmodesmata between mesophyll cells. These plasmodesmata possess amorphous, electron-opaque structures, termed sphincters, that extend from plasma membrane to desmotubule near the orifices of the plasmodesmata. The cytoplasmic sleeve is filled by the sphincters where they occur; elsewhere it is open and entirely free of particulate or spokelike components. The desmotubule is tightly constricted and has no lumen within the sphincters, but between the sphincters it is a convoluted tubule with an open lumen. 2) Plasmodesmata that traverse the walls of chlorenchymatous bundle-sheath cells and mestome-sheath cells. In addition to the presence of sphincters, these plasmodesmata are modified by the presence of suberin lamellae in the walls. Although the plasmodesmata are quite narrow and the lumens of the desmotubules are constricted where they traverse the suberin lamellae, the cytoplasmic sleeves are still discernible and appear to contain substructural components there. 3) Plasmodesmata between parenchymatous cells of the vascular bundles. These plasmodesmata strongly resemble those found in the roots of Azolla, in that their desmotubules are closed for their entire length and their cytoplasmic sleeves appear to contain substructural components for their entire length. The structural variations exhibited by the plasmodesmata of the sugarcane leaf are compared with those proposed for a widely-adopted model of plasmodesmatal structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00195331
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    Paper (German National Licenses)
    Fulltext
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