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  • 1990-1994  (2)
  • 1985-1989  (2)
  • Microspore  (2)
  • Nicotiana tabacum  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Sexual plant reproduction 2 (1989), S. 137-141 
    ISSN: 1432-2145
    Keywords: Humidity ; Temperature stress ; Nicotiana tabacum ; Pollen germination ; Pollen membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The prolonged exposure of pollen Nicotiana tabacum to high humidity at both room temperature and 38° C did not affect membrane integrity as revealed by the fluorochromatic reaction (FCR) test, but did affect pollen vigour. At room temperature germination was not affected, although tube growth was reduced; at 38° C, there was both a reduction in tube growth and delayed germination. When the pollen was subjected to 1 h hydration followed by 1 h desiccation (up to a maximum of four cycles) at room temperature, a reduction in the FCR, germination and tube length after each desiccation treatment was observed. Subsequent hydration fully restored the FCR, but only partially restored germination and tube growth. At 38° C, however, FCR, germination, and tube growth were drastically reduced. The implications of these results on the relationship between FCR and germinability, the responses of pollen exposed to humidity and temperature stress in the field, and on pollen storage are discussed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Sexual plant reproduction 4 (1991), S. 104-109 
    ISSN: 1432-2145
    Keywords: High humidity and temperature stress ; Nicotiana tabacum ; Tobacco ; Pollen viability ; Vigour ; Semi-vivo technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Responses of pollen grains of Nicotiana tabacum to high humidity (95% RH, 4 h) and temperature (38°/45° C, 4 h) stresses were investigated. Pollen grains were subjected to only RH or only temperature, or to both of these stresses. Their viability was assessed on the basis of the fluorochromatic reaction (FCR) test, and vigour was assessed on the basis of the time taken for in vitro germination as well as on the emergence of pollen tubes through the cut end of semi-vivo implanted styles. None of the stress conditions affected pollen viability and high RH or high temperature stress did not individually affect pollen vigour. However, pollen vigour was markedly affected when both the stresses were given together. Pollen grains subjected to high RH at 38° C took a longer time to germinate in vitro and the pollen tubes emerged later from the cut end of the semi-vivo styles; division of the generative cell was also delayed. Pollen grains subjected to high RH at 45° C failed to germinate in vitro, but did germinate on the stigma. Many pollen tubes subjected to this treatment showed abnormalities, and the growth of pollen tubes in the pistil was much slower than that observed in other treatments. Pollen samples subjected to all of the stress conditions were able to induce fruit and seed set. The implications of these results on the relationship between the FCR test and viability, and between viability and vigour, especially in stressed pollen, are discussed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 158 (1990), S. 26-32 
    ISSN: 1615-6102
    Keywords: Secale ; Microspore ; Pollen wall ingrowths ; Transfer cells ; Plasmatubules ; Pollen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In the mature microspore ofSecale cereale, a set of wall ingrowths deposited as the first (outer) intine layer between exine and the microspore plasma membrane, are revealed by electron microscopy. The wall ingrowths form a girdle in the vicinity of the apertural region at the external pole of microspore which is in contact with the tapetum, so the microspore can be considered as a transfer cell which is polarized. After microspore division the second (inner) intine layer is deposited by the vegetative cell and forms a labyrinth of branched wall ingrowths. As a result, the periphery of a vegetative cell is also irregular and appears as very thin plasmatubules or evaginations delimited by plasma membrane and penetrating the pollen wall. The possible functions of the microspore as a transfer cell and the wall-membrane system of the vegetative cell are discussed.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 148 (1989), S. 1-7 
    ISSN: 1615-6102
    Keywords: Microspore mother cell ; Microspore ; Impatiens sultani ; Cytoplasm ; Organelles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary From early prophase stage until probaculae formation within the tetrad stage considerable cytoplasmic changes occur. The changes merely concern the ribosome population, the plasma matrix and, the endomembrane system formed by endoplasmic reticulum, dictyosomes and dictyosome-vesicles. The ultrastructure and morphology of mitochondria and plastids remain fairly unchanged, apart from the mobilization of starch during primexine formation. During meiotic prophase there is an increase in ribosome number, accompanied by the presence of nucleoloids in the cytoplasm. Simultaneously the electron density of the cytoplasm strongly increases, indicating a fair increase in protein content. Nucleoloids are also observed in the cytoplasm after primexine formation, accompanied by localized accumulation of ribosomes. Up to the individualization of the microspores the dictyosomes are in an inactive state. After that, they become very active, especially during primexine formation when numerous large dictyosome-vesicles are present. The endoplasmic reticulum (ER), initially in a plate-like configuration, disappears from the cytoplasm during primexine formation. Abundant, smooth and tubular ER is present when probaculum formation starts.
    Type of Medium: Electronic Resource
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