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  • 1
    Electronic Resource
    Electronic Resource
    Ultrastructure and histochemistry of Citrus limon (L.) stigma (1982)
    Springer
    Planta 156 (1982), S. 1-9 
    Details
    ISSN: 1432-2048
    Keywords: Citrus ; Development (stigma) ; Exudate (stigmatic) ; Stigma (histochemistry, ultrastructure)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Citrus limon has a “wet” stigma which can be divided in two zones: a glandular superficial one formed by papillae, and a non-glandular one formed by parenchymatic cells. The stigmatic exudate is produced by the papillae after the latter have reached their ultimate size. The papillae of the mature pistil are of varying size and composition. Both the unicellular and multicellular ones are present. The cells at the base of the papillae are rich in cytoplasm, whereas the tip cells are vacuolated. Histochemical analysis has shown that the exudate of Citrus is composed of lipids, polysaccharides, and proteins. Our results indicate that the lipidic component is produced and secreted first, followed by production and secretion of the polysaccharidic component. The lipidic component of the exudate is produced in the basal papillae cells and accumulates as droplets in dilated parts of the smooth endoplasmic reticulum (SER). Subsequently the lipid droplets are transported to the plasma membrane, and transferred by the latter into the cell walls. Then the exudate component is accumulated in the intercellular spaces and in the middle lamellar regions of the walls. Subsequently, the polysaccharidic component of the exudate is produced and secreted by the tip cells of the papillae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393436
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Ultrastructural investigations on Lycopersicum peruvianum pollen activation and pollen tube organization after self-and cross-pollination (1980)
    Springer
    Planta 150 (1980), S. 211-217 
    Details
    ISSN: 1432-2048
    Keywords: Lycopersicum ; Pollen activation ; Pollen tube ; Self-incompatibility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract No differences have been observed “in vivo” between Lycopersicum peruvianum compatible and incompatible pollen during activation and pollen tube emission and organization, that is until 4 h and 30 min after pollination. During pollen activation the main events are the setting free of rough endoplasmic reticulum (RER) cisterns which were “stacked” in the mature pollen, the increase in the number of polysomes, and a great activity of the dictyosomes. Immediately after germination of the vegetative nucleus and the generative cell move into the tube, the generative cell diviting to form the male gametes; the tube then becomes organized in four zones. This series of changes is similar to what has already been observed “in vitro” except that in vitro the generative cell remains undivided and the whole process from seeding to tube organization takes 3 h instead of 4 h and 30 min after pollination, as it does in vivo. Our findings are compatible with the main models of the tube inhibition mechanism proposed till now.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00390828
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    In vitro double fertilization in Nicotiana tabacum (L.): fusion behavior and gamete interaction traced by video-enhanced microscopy (2000)
    Springer
    Sexual plant reproduction 12 (2000), S. 267-275 
    Details
    ISSN: 1432-2145
    Keywords: Key words Nicotiana tabacum ; In vitro fertilization ; Gamete interaction ; Cytology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  In vitro double fertilization in tobacco was carried out with attention to fusion behavior and gamete interaction. Structural and cytological events indicating possible reaction to the fusion of sperm-egg and especially sperm-central cell were recorded by video-enhanced microscopy. Generative cells were fused with the egg cell or central cell as a control system to better understand gamete interaction. As early as adherence of the male cell, the female cell showed response by means of cytoplasm strand formation. After gamete fusion, cytoplasm activation in the egg cell was observed as long distance movement of organelles. In fertilized central cells, however, fusion did not result in notable cytological change within 30 min. Male nuclear movement recorded in the female cell illustrated two different patterns of movement which showed similarity to organelle movement. The dynamics of male and female nuclear fusion after in vitro fertilization was also recorded in the central cell. It revealed that the fusion process requires only a few seconds and is similar to that of gamete fusion in vitro. This may offer a new clue for understanding how female and male nuclei attract, adhere and finally fuse each other.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004970050194
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  • 4
    Electronic Resource
    Electronic Resource
    In vitro double fertilization in Nicotiana tabacum (L.): polygamy compared with selected single pair somatic protoplast and chloroplast fusions (2000)
    Springer
    Sexual plant reproduction 13 (2000), S. 113-117 
    Details
    ISSN: 1432-2145
    Keywords: Key words Cell fusion ; Gamete interaction ; In vitro polygamy ; Nicotiana tabacum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  In vitro polygamy was studied mainly by using isolated sperm and central cells of tobacco in order to elucidate the mechanism that might be involved in preventing in vivo polygamy. In 17.5% 4000 M.W. polyethylene glycol, only when two sperm cells were made close enough to each other and adhered to a female cell simultaneously was polygamy possible. If one sperm cell fused with the egg or central cell, within 30 min another sperm cell could not fuse with the same egg or central cell. Similar phenomena were found in selected single somatic cell fusion. When more than two protoplasts adhered to each other simultaneously, fusion was always successful; after two protoplasts fused, within 30 min the fusion products could not fuse with another protoplast under the same conditions. This comparative study revealed this characteristic to be shared by both sexual and somatic cell fusion. However, after cytoplasm reorganization was complete in the fusion product, it was possible for the fusion product to fuse with the third protoplast. This indicates that the obstruction to additional fusion was present only during a certain period after the preceding fusion under certain condition. The possible reason for the effect is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004970000044
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    Paper (German National Licenses)
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