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  • 1
    Electronic Resource
    Electronic Resource
    Germination and early tube development in vitro of Lycopersicum peruvianum pollen: Ultrastructural features (1977)
    Springer
    Planta 136 (1977), S. 239-247 
    Details
    ISSN: 1432-2048
    Keywords: Early tube development ; In vitro germination ; Lycopersicum ; Pollen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Morphologic changes occurring during pollen grain activation and ultrastructural features of Lycopersicum peruvianum Mill. pollen tube during the first stages of growth in vitro have been studied. The more evident morphologic changes during activation, in comparison to those already described for mature inactive pollen, concern dictyosomes, rough endoplasmic reticulum (RER), and ribosomes. The dictyosomes are very abundant and produce “large” and “small” vesicles. Near the germinative pores both types of vesicles are present, while all along the remaining cell wall only the large type is observed. These latter react weakly to Thiéry's test and probably contain a callose precursor necessary for the deposition of a callosic layer lining at first only the inner side of the functioning pore and occasionally the other two pores, and subsequently the entire inner surface of the cell wall. The small vesicles, highly positive to Thiéry's test, are present only near the pores and could be involved in the formation of the pectocellulosic layer of the tube wall. The setting free of RER cisterns, which in the mature inactive pollen were aggregated in stacks, coinciding with polysome formation and resumption of protein synthesis, is in accord with the hypothesized role of RER cistern stacks as a reserve of synthesizing machinery. The pollen tube reaches a definitive spatial arrangement soon after the generative cell and vegetative nucleus have moved into it. At this stage four different zones that reflect a functional specialization are present. In the apical and subapical zone two types of dictysosome-originated vesicles, similar to those found in the activated pollen grain, are present. Their role in the formation of the callosic and pectocellulosic wall layers seems to be the same as in the activated pollen grain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00385991
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  • 2
    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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  • 3
    Electronic Resource
    Electronic Resource
    Ultrastructural aspects of pollen tube growth inhibition after gamma irradiation in Lycopersicum peruvianum (1977)
    Springer
    Theoretical and applied genetics 49 (1977), S. 297-303 
    Details
    ISSN: 1432-2242
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Gamma ray treatments at various doses were applied to flowers after cross-compatible pollinations (S1S4 × S12S13) and self-incompatible pollinations (S1S4 × S1S4). After 200 kR treatment (highest dose) a high percentage of pollen became non-viable, and tube growth of all the germinated pollen was inhibited at the first third, or just before half the length of the style. Observations on the ultrastructural aspects revealed that the pollen tubes were destroyed by a precise degradation process which led to the disappearance of the inner wall, lysis of the tube, accumulation of several bipartite particles and alteration of endoplasmic reticulum into a whorl of concentric circles. These results indicated that the high dose of gamma rays probably interferes with protein synthesis. The ultrastructural aspects of compatible pollen tubes after gamma irradiation were similar to those of self-incompatible tubes and therefore it is suggested that cessation of protein synthesis might also be a result of incompatibility. Electron microscopy observations after treatment with 200 kR gamma rays on flowers after self-incompatible pollination (S1S4 × S1S4) showed that gamma irradiation affects the self-incompatibility reaction; but the results obtained so far are difficult to explain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00275137
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  • 4
    Electronic Resource
    Electronic Resource
    Ultrastructure of transmitting tissue of Lycopersicon peruvianum style: Development and histochemistry (1976)
    Springer
    Planta 132 (1976), S. 305-312 
    Details
    ISSN: 1432-2048
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The development of the transmitting tissue of the style of Lycopersicon peruvianum goes, after the completion of cell division and cell wall formation, through two distinct phases. During the first phase, the cells enlarge and the main part of the intercellular substance, consisting of pectins, is formed. During the second phase, the cells form an extensive rough endoplasmic reticulum (RER) and proteins are incorporated in the intercellular substance. A possible role of these proteins in the incompatibility reaction is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00399731
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  • 5
    Electronic Resource
    Electronic Resource
    Callose deposition and plug formation in Petunia pollen tubes in situ (1976)
    Springer
    Planta 133 (1976), S. 35-40 
    Details
    ISSN: 1432-2048
    Keywords: Pollen tube ; Style ; Callose ; Petunia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In Petunia pollen tubes growing in the style there appear to be two ways of callose deposition. The first one is callose deposition outside the plasma membrane as a distinct layer closely appressed to the cell wall. The second one is callose deposition within the cytoplasm as distinct callose grains, leading to the formation of callose plugs. This second way is accompanied by a characteristic ultrastructure of the cytoplasm, namely strong electron-density of the plasma matrix, partial absence of the plasma membrane and the absence of plastids and dictyosomes. For both ways of callose deposition a mechanism is proposed and the function of callose plugs is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00386003
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  • 6
    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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  • 7
    Electronic Resource
    Electronic Resource
    Viral particles in developing pollen grains of Olea europaea (1977)
    Springer
    Planta 137 (1977), S. 1-4 
    Details
    ISSN: 1432-2048
    Keywords: Olea ; Pollen ; Viral particles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Double-walled tubules containing rows of isodiametric virus particles were observed in developing pollen grains of Olea europaea L. cultivar Correggiolo. Sometimes the tubules are contained in another double-walled tubular structure or in a tubular endoplasmic reticulum cistern. The viruses are present in the cytoplasm from the microspore mother cell stage up to the microspore stage but just before the first haploid mitosis they are to be found only in the pores, inside the evaginations formed by the plasmalemma. During the last phase of pollen grain development, after the germinative pores are completed, the viruses disappear.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00394426
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  • 8
    Electronic Resource
    Electronic Resource
    The secretory stigma inLycopersicum peruvianum Mill.: Ontogenesis and glandular activity (1978)
    Springer
    Protoplasma 96 (1978), S. 173-187 
    Details
    ISSN: 1615-6102
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The aim of the present study has been to elucidate the cytology of the glandular stigma inLycopersicum peruvianum Mill. and the mechanism of the secretory process during the stigma development. The glandular stigma (papillae and superficial stigmatic tissue) has been studied by light and electron microscopy (S.E.M. and T.E.M.). At anthesis, the longitudinal intercellular spaces are filled with exudate in the form of heterogeneous droplets and form an intercommunicating system which allows transmitting tissue to communicate with superficial papillae. The presence of cytoplasmic droplets similar in appearance to the exudate has been noted in the developing stigmatic tissue. Cytoplasmic events which may be related to their production include transitory vacuolar accumulations, modifications of the morphology of plastids and development of smooth endoplasmic reticulum. At anthesis, observations possibly related to the origin of these droplets include their contiguity with endoplasmic reticulum cisternae and their relationship to the Golgi apparatus. Some observations suggest that cytoplasmic droplets are extruded by a process of exocytotic secretion. In addition, the cytoplasmic transport of secretory products in a non-visible form may explain the involvement of several cell compartments and the heterogeneity of the secretory products.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279584
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