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  • 1
    Electronic Resource
    Electronic Resource
    Gibberellins regulate seed germination in tomato by endosperm weakening: a study with gibberellin-deficient mutants (1987)
    Springer
    Planta 171 (1987), S. 525-531 
    Details
    ISSN: 1432-2048
    Keywords: Endosperm weakening ; Germination (seed) ; Gibberellin and seed germination ; Lycopersicon (mutant, germination) ; Mutant (gibberellin deficient)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The germination of seeds of tomato [Lycopersicon esculentum (L.) Mill.] cv. Moneymaker has been compared with that of seeds of the gibberellin-deficient dwarf-mutant line ga-1, induced in the same genetic background. Germination of tomato seeds was absolutely dependent on the presence of either endogenous or exogenous gibberellins (GAs). Gibberellin A4+7 was 1000-fold more active than commercial gibberellic acid in inducing germination of the ga-1 seeds. Red light, a preincubation at 2°C, and ethylene did not stimulate germination of ga-1 seeds in the absence of GA4+7; however, fusicoccin did stimulate germination independently. Removal of the endosperm and testa layers opposite the radicle tip caused germination of ga-1 seeds in water. The seedlings and plants that develop from the detipped ga-1 seeds exhibited the extreme dwarfy phenotype that is normal to this genotype. Measurements of the mechanical resistance of the surrounding layers showed that the major action of GAs was directed to the weakening of the endosperm cells around the radicle tip. In wild-type seeds this weakening occurred in water before radicle protrusion. In ga-1 seeds a similar event was dependent on GA4+7, while fusicoccin also had some activity. Simultaneous incubation of de-embryonated endosperms and isolated axes showed that wild-type embryos contain and endosperm-weakening factor that is absent in ga-1 axes and is probably a GA. Thus, an endogenous GA facilitates germination in tomato seeds by weakening the mechanical restraint of the endosperm cells to permit radicle protrusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392302
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  • 2
    Electronic Resource
    Electronic Resource
    The genetic control of the enzyme UDP-glucose: 3-0-flavonoïd-glucosyltransferase in flowers of Petunia hybrida (1983)
    Springer
    Theoretical and applied genetics 65 (1983), S. 349-352 
    Details
    ISSN: 1432-2242
    Keywords: Flavonoïds ; Glucosyltransferase ; Genetic control ; Petunia hybrida
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Four genes controlling the conversion of dihydroflavonols into anthocyanins have been investigated for their effect on UDP-Glucose: 3-0-flavonoïd glucosyltransferase activity, one of the enzymes involved in this conversion. An1 and An2 control the bulk of UFGT activity; a homozygous recessive for one of these genes shows an activity of 5–20% of the wildtype value. In a homozygous double recessive some 5% activity is still found while in mutants homozygous recessive for An6 or An9, UFGT activity is lower. In F2 progenies segregating for An6 or An9, however, no difference in UFGT activity was found between homozygous recessive and dominant plants. Mutants blocked in a biosynthesis step preceding the formation of dihydroflavonols show normal UFGT activity levels, indicating that no anthocyanidins are needed for UFGT induction. In addition to delphinidin, myricetin was used as a substrate. The results obtained indicate the probability that both substrates can be glucosylated by the same UFGT enzyme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00276576
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  • 3
    Electronic Resource
    Electronic Resource
    Polyploidization in embryogenic microspore cultures ofBrassica napus L. cv. Topas enables the generation of doubled haploid clones by somatic embryogenesis (1999)
    Springer
    Protoplasma 208 (1999), S. 240-247 
    Details
    ISSN: 1615-6102
    Keywords: Androgenesis ; Brassica napus ; Ploidy ; Pollen ; Rapeseed ; Somatic embryogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Embryogenic microspore and pollen culture followed by subculture of microspore-derived plantlets enabled the production of clones ofBrassica napus cv. Topas. Flow-cytometric analysis revealed that most microspore- and pollen-derived embryos (pEMs) were haploid initially. Spontaneous diploidization occurred at the globular stage of the pEMs, and was expressed as the relative increase of the 2C and 4C nuclear DNA content. Diploidization occurred throughout various organs of the pEMs and resulted in the formation of haploid and doubled haploid chimerics. In some embryos, nearly all cells were doubled haploid. From early cotyledon stage onward, pure haploid embryos were not observed anymore. At late cotyledon and germination stages, pure doubled haploid embryos and plantlets increased in number. Tetraploid pEMs were found occasionally. A culture regime was established to induce somatic embryos on the pEM-derived young plantlets. The ploidy of the somatic embryos varied highly and tended to be the same as that of the tissue at the initiation site on the pEM-plant. The results show that during the embryogenic development ofB. napus microspores, spontaneous diploidization occurs at globular stage, and increases progressively, resulting in the formation of chimerical haploid and doubled haploid plants as well as pure doubled haploid plants; ploidy neither affects pEM development at embryo developmental stages nor somatic embryogenesis, that starts on young pEM-derived plantlets; doubled haploid somatic embryos can be cloned from single pEM-derived plantlets; and doubled haploid embryos develop to fertile plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279095
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  • 4
    Electronic Resource
    Electronic Resource
    The relationship between powdery mildew (Sphaerotheca fuliginea) resistance and leaf chlorosis sensitivity in cucumber (Cucumis sativus) studied in single seed descent lines (1995)
    Springer
    Euphytica 81 (1995), S. 193-198 
    Details
    ISSN: 1573-5060
    Keywords: cucumber ; Cucumis sativus ; leaf chlorosis ; powdery mildew ; single seed descent ; Sphaerotheca fuliginea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The genetic relation between powdery mildew resistance and sensitivity for leaf chlorosis of glasshouse cucumber was investigated. The powdery mildew resistant, leaf chlorosis sensitive hybrid variety ‘Profito’ was crossed with the powdery mildew susceptible, non chlorosis sensitive hybrid variety ‘Corona’. Forty four F6 inbred lines of this cross, produced by single seed descent, were tested for powdery mildew resistance (PMR) and leaf chlorosis sensitivity (LCS). PMR and LCS were positively correlated (r=0.59). One or more of the PMR genes probably causes LCS as a pleiotropic effect or is closely linked to LCS, but also other factors, not genetically linked to PMR can cause LCS. Five F6 lines combined a significantly higher level of PMR than ‘Corona’ with a significantly lower LCS than ‘Profito’. Three of these lines could hardly be distinguished from ‘Corona’ for the level of LCS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00025433
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    Paper (German National Licenses)
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