Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 78 (1990), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The effect of ethytene on in vitro flower bud formation in thin-layer explants from tobacco pendicels (Nicotiana tabacum L. cv. Samsun) was studied Endogenous ethylene production was stimulated by l-minocyclopropanc-l-carhoxylic acid (ACT), and inhibited by aminoethoxyviny lglycine (AVG). resulting in higher and lower ethylene accumulation. respectively. In the presence of an elevated ethylene concentration, the number of flower buds formed after 7 days of culture in explants was increased, compared with the control. Treatment with AVG or with AgNO3 which blocks ethylene action resulted in decreased bud numbers after 7 days of culture. A different effect of ethylene was visible after 14 days of culture, when regeneration was complete. Treatment with AgNO3 led to more bud regeneration, and increasing ethylene concentrations to lower bud numbers. The endogenous production of ethylene was enhanced by high concentrations of 1-naphthaleneacetic acid (NAA).The inhibitory effect of applied ethylene was almost 100% in explants cultured at low concentrations of NAA (below 1 μM). but hardly visible at high concentrations (4.5 μM). As a consequence, the optimal NAA concentration shifted to a higher value in the presence of ethylene. These results are interpreted as a reduction in tissue sensitivity to auxin and in regenerative capability by ethylene. The effect of ethylene on auxin action is not exerted at the level of hormone concentration. Neither NAA uptake nor conversion to conjugates was effected by ethylene.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1432-2145
    Keywords: In situ hybridization ; Pollen-specific gene expression ; mRNA ; Confocal laser scanning microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The application of confocal laser scanning microscopy together with in situ hybridization experiments in tobacco pollen enabled a detailed localization of a pollen-specific mRNA. The three-dimensional distribution of this specific mRNA over the whole pollen grain was reconstructed by means of optical sections of one specimen.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1432-2048
    Keywords: Pollen (development) ; Lilium (pollen development) ; mRNA expression (pollen development) ; Microgametophyte ; Microspore ; Nicotiana (pollen development)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Homogeneous populations of developing microspores and pollen from anthers of lily (Lilium longiflorum Thumb.) and tobacco (Nicotiana tabacum L.) show a continuous production of biomass, reaching a maximum in young pollen. The rate of RNA synthesis was 460 fg · h−1 in young binucleate cells, 138 fg · h−1 in late binucleate cells and 56 fg · h−1 in microspores. The mRNA population in developing pollen can be separated into three groups. In the first group, certain types of mRNAs are present at a constant level during all stages of development. A second group is characteristic of young pollen and increases quantitatively until anthesis. A third group is seen transiently; to this belong mRNAs present only before mitosis or at a distinct cell stage after mitosis. Some of the translation products of this latter group of mRNAs showed similarities between lily and tobacco on two-dimensional gels in respect of molecular weight and isolectric point, indicating that those mRNAs and proteins play a role in the regulation of pollen development.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1432-2048
    Keywords: Auxin (flower bud, dose) ; Cell culture (flower bud formation) ; Flower bud formation ; Nicotiana (flower bud formation)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Short-term applications of very high concentrations of 1-naphthaleneacetic acid (NAA) to expiants from flower stalks of tobacco (Nicotiana tabacum L. cv. Samsun) induced flower-bud regeneration to the same extent as longer or continuous incubation on lower concentrations. The maximum number of flower buds per explant after 15 d of culture was obtained not only by continuous culturing at 1 μmol·l−1 NAA but also by 12 h of culturing at 22 μmol·l−1 or 0.5 h at 220 μmol· l−1, followed by incubation on medium without auxin for the remaining period. Continuous application of such high concentrations resulted in callus formation or caused the death of the explanted tissue. In all experiments in which auxin concentration and time of application were independently varied, the product of concentration and time determined the number of buds formed. Most, but not all, of the NAA taken up by the tissues was converted into conjugates. In expiants which had received a dose which was optimal for regeneration, the internal concentration of free NAA remaining beyond the pulse period was between 1.7 and 6.2 μmol·l−1. Suboptimal applications led to lower values, supraoptimal treatments to much higher internal concentrations. The physiological effect, which depends on the internal hormone concentration, thus manifested itself as dose-dependent with regard to applied hormone.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1432-2048
    Keywords: Auxin (flower bud, dose) ; Cell culture (flower bud formation) ; Flower bud formation ; Nicotiana (flower bud formation)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Short-term applications of very high concentrations of 1-naphthaleneacetic acid (NAA) to expiants from flower stalks of tobacco (Nicotiana tabacum L. cv. Samsun) induced flower-bud regeneration to the same extent as longer or continuous incubation on lower concentrations. The maximum number of flower buds per explant after 15 d of culture was obtained not only by continuous culturing at 1 μmol·l−1 NAA but also by 12 h of culturing at 22 μmol·l−1 or 0.5 h at 220 μmol· l−1, followed by incubation on medium without auxin for the remaining period. Continuous application of such high concentrations resulted in callus formation or caused the death of the explanted tissue. In all experiments in which auxin concentration and time of application were independently varied, the product of concentration and time determined the number of buds formed. Most, but not all, of the NAA taken up by the tissues was converted into conjugates. In expiants which had received a dose which was optimal for regeneration, the internal concentration of free NAA remaining beyond the pulse period was between 1.7 and 6.2 μmol·l−1. Suboptimal applications led to lower values, supraoptimal treatments to much higher internal concentrations. The physiological effect, which depends on the internal hormone concentration, thus manifested itself as dose-dependent with regard to applied hormone.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 79 (1990), S. 143-144 
    ISSN: 1432-2242
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 83 (1992), S. 400-402 
    ISSN: 1432-2242
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 82 (1991), S. 662-663 
    ISSN: 1432-2242
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1432-2145
    Keywords: Microsporogenesis ; In-vitro pollen maturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Immature pollen grains of Nicotiana tabacum L., cv ‘Petit Havana’ were isolated at the mid-binucleate stage and cultured in vitro. During the first 66 h of in-vitro culture the pollen developed the same ability to set seed and germinate as pollen matured in vivo. No fertile pollen was produced when protein synthesis was inhibited temporarily at an early stage of development. In the case of inhibition at day 2 of development a delay in the total time necessary for maturation was observed that was equal to the length of time the inhibitor was applied. Hybridization experiments with a pollen-specific cDNA probe showed that the pattern of gene expression in vitro was similar to that in vivo. However, the model system differs from natural pollen development with respect to the dehydration period, which is absent in the model system, and the synthesis of proteins. Protein synthesis of in-vitro cultured pollen differed significantly from that of pollen developing in vivo, even though pollen maturation in vitro proceeded in the same time as in vivo, and led to fully matured fertile pollen. Pollen development in vitro is thus an ideal model system for studying gene expression in relation to fertility and for experimental manipulation of microsporogenesis.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of plant growth regulation 10 (1991), S. 79-83 
    ISSN: 1435-8107
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Flower stalk explants of tobacco cultured on a medium with an auxin and cytokinin regenerate flower buds within 14 days. The optimal medium concentrations of dihydrozeatin (DHZ) and benzyladenine (BA) were both 1 μM. The presence of DHZ in the culture medium was only essential during an initiation period of 7 days, whereas BA was needed only during the first 4 days. The difference in length of the initiation period is neither explained by the unequal uptake rates of the cytokinins nor by differences in their conjugation. At the medium concentration optimal for bud formation, the internal concentration of DHZ was two to three times the internal concentration of BA, which could be attributed to faster uptake of DHZ. It is concluded from the combined data that DHZ is less active in inducing flower bud formation than BA and that the exogenous cytokinins play only a role during the initiation phase of bud regeneration.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...