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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 76 (1989), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The relation between root differentiation and accumulation of biocidal thiophenes was studied in stem calli of two Tagetes species. Disorganized tissues of T. erecta were low in thiophene production. A sharp rise in thiophene content coincided with the emergence of roots on the calli. Root regeneration and the amount of thiophenes produced were found to be quantitatively related. Callus tissues of T. minuta did not differentiate into organs. Nevertheless, they accumulated thiophenes throughout the incubation period. Light at 12 W m- stimulated thiophene production in T. erecta without having an apparent effect on root regeneration. In T. minuta even low irradiance levels (2 W m∼2) strongly inhibited thiophene accumulation. Under favorable conditions thiophene concentrations in calli of both species were comparable to or somewhat lower than the levels in roots on the plants and in excised, cultured roots of T. erecta. We conclude that in calli of T. erecta thiophene accumulation is coupled to root regeneration whereas a different control mechanism allowing for accumulation in disorganized tissues is operative in T. minuta.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 74 (1988), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Benzyladenine (BA) was found to regulate the number of flower buds regenerated in vitro from pedicel tissue of tobacco. Flower bud induction was particularly sensitive to BA levels in the range of 0.45 to 1.0 μM, where a two-fold increase in concentration caused a threefold rise in the number of buds. When tissues were fed radioactive BA for 24h, only 9–12% of the counts were recovered in the original compound. The rest was present in metabolites, tentatively identified as the mono-, di- and triribotides, 7- and 9-glucosides and 9-riboside of BA. The amount of growth regulator taken up and the quantities of BA and its metabolites in the explants were all linearly related to the concentration of the medium. The internal BA concentration was ca 60% of the level in the medium after 24 h. When the concentration in the medium was raised, relatively more BA remained in the non-conjugated form. However, this change in the equilibrium between BA and the conjugates is too small to account for the steep rise in the curve representing concentration vs effect between 0.45 and 1.0 μM.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: To study the role of translocation of gibberellin (GA) intermediates or bioactive GAs from other plant parts to buds during early flower development in tomato (Solanum lycopersicon), the effect of grafting and paclobutrazol (PAC) treatment on the expression of tgas100 and tgas118, two GA-regulated mRNAs, was analysed. Both mRNAs accumulated in a dose-dependent fashion. Application of 0.5 ng GA3 per bud to developmentally arrested flower buds of a GA-deficient mutant of tomato (gib-1) induced tgas100 expression, while the tgas118 abundance increased. For obtaining normal flower development through anthesis in the mutant, a single GA3 treatment was required of at least 5 ng GA3 per bud. In wild-type flower buds, PAC decreased the abundance of tgas100 and tgas118 mRNAs either when PAC was sprayed on whole plants or directly applied to buds. When only the wild-type buds were treated with PAC, the expression profiles characteristic for untreated buds were not restored by translocation of endogenous GAs. Grafting of gib-1 scions onto wild-type donor plants did not result in normal flower development or expression profiles like in wild-type buds. We conclude that the role of GA transport in early flower development of tomato is negligible and that the GAs required for development have to be synthesized in the flower bud itself.
    Type of Medium: Electronic Resource
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  • 4
    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
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  • 5
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In this paper the effects of indole-3-acetic acid (IAA) on growth of Tagetes patula hairy root cultures and secondary product formation are presented. The biosynthesis of thiophenes, sulfurous compounds with nematicidal activity, was inhibited by IAA application, as was evident from a decrease of [35S] sulfur incorporation. The inhibition only occurred after the roots had developed numerous laterals as a result of auxin action. However, in roots cultured in the absence of IAA, there was no significant correlation between branching and thiophene accumulation. Therefore, development of lateral roots is not a sufficient condition for a low capacity to synthesize thiophenes. The highest rate of thiophene accumulation in the roots culture is at its maximum. Hence, growth and the production of thiophenes appear to be compatible in T. Patula hair roots.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 296 (1982), S. 72-74 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Protoplasts, isolated from leaves of aseptically grown N. tabacum SRi shoots, were cultured in K3 medium supplemented with phytohormones8 (see Table 1 legend). Normally, they form a new cell wall, divide and generate cell colonies (calli) which will eventually give rise to shoot-regenerating calli. ...
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 277 (1979), S. 129-131 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Fig. 1 Electropherogram of the products present in the reaction mixture prepared to detect LpDH activity in extracts of different transformed'calli and shoots. The enzyme activity was assayed according to Otten14. a Channels, reaction mixture at f = 0; b channels, reaction mixture at t = 60 min; l, ...
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell reports 15 (1995), S. 133-137 
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Thiophenes are polyacetylene-related heterocyclic metabolites. Some of these compounds are phototoxic, but the bithiophenes occurring inTagetes mainly accumulate in the root where photo-activation is not likely to occur. A cell-free extract from the fungusFusarium oxysporum induced biosynthesis of hydrophilic thiophenes in root cultures and roots of seedlings ofTagetes patula. The thiophenes formed were partially excreted into the culture medium. The excreted thiophenes inhibited fungal growth in the absence of light and thus may play a role in the biochemical defense against pathogens.
    Type of Medium: Electronic Resource
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  • 9
    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
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  • 10
    ISSN: 1432-2048
    Keywords: Agrobacterium ; Auxin and thiophene in roots ; Root culture ; Root morphology ; Tagetes ; Thiophene ; Transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Roots of marigold (Tagetes patula L.) accumulate thiophenes, heterocyclic sulfurous compounds with strong biocidal activity. In detached roots cultured in vitro, the thiophene content was 5 μmol·(g fresh weight)-1 which is 25-times higher than in roots attached to the plant. In roots derived from tissues transformed by Agrobacterium tumefaciens and A. rhizogenes, the morphology and thiophene content varied with the bacterial strain used. Transformation stimulated the elongation of the root tips and the formation of lateral roots but lowered the thiophene level to 20–50% relative to the concentration in untransformed detached roots. A negative correlation was found between the number of laterals in a root system and the thiophene content. Extensive branching and a decrease in thiophene accumulation was evoked in untransformed roots by indole-3-acetic acid (1–10 μmol·l-1) added to the medium. Within the roots, the highest thiophene concentrations were found in the tips. The results indicate that auxin directly or indirectly plays a role in the regulation of the thiophene level in root tips.
    Type of Medium: Electronic Resource
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