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  • 1
    Electronic Resource
    Electronic Resource
    Extracellular proteins and early embryo development in Citrus nucellar cell cultures (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 82 (1991), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Highly efficient synchronous embryogenesis was induced in suspension cultures of sour orange (Citrus aurantium L.) by a change in the carbon source of the growth medium from sucrose to glycerol. In liquid culture the embryos developed into globular structures during a three week period. Embryo development showed an absolute requirement for the continued presence of glycerol. The embryo cell cultures turned green in the light, but light did not affect the course of development. The profiles of soluble cellular protein extracts of embryo and proembryogenic (PEM) cells were very similar as judged by two-dimensional polyacrylamide gel electrophoresis. However, major differences were detected in the profiles of extracellular proteins. PEM cells accumulated extracellular glycoproteins of 53–57 kDa mass. Upon subculture in glycerol containing medium, the accumulation of these proteins ceased within two days. Developing embryos accumulated at least 4 new extracellular polypeptides of 41–42 kDa mass. In addition to these polypeptides, stage specific peroxidases and proteases were found. The relatively extended duration and synchrony in which these early developmental events take place make Citrus cultures an especially useful system for the study of early events in plant embryogenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1991.tb02954.x
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  • 2
    Electronic Resource
    Electronic Resource
    The effect of B chromosomes on meiotic and pre-meiotic spindles and chromosome pairing in Triticum/Aegilops hybrids (1972)
    Springer
    Chromosoma 38 (1972), S. 367-385 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Diploid populations of Aegilops mutica and Aegilops speltoides containing B chromosomes have been used as male parents in crosses with aneuploid genotypes of Triticum aestivum to investigate the effect of B chromosomes on meiotic homologous and homoeologous chromosome pairing. F1 hybrids of T. aestivum/Ae. mutica and T. aestivum/Ae. speltoides segregated into four classes with regard to the degree of meiotic chromosome pairing, irrespective of the presence of B chromosomes. The B chromosomes do not introduce factors altering the level of pairing other than that due to the natural allelic and gene variation occurring in the diploids. Similarly no reduction in pairing of homologous chromosomes was observed in genotypes in which pairs of homologues co-existed with B chromosomes. However, a significant drop in chiasma frequency was observed in F1 hybrids of T. aestivum × Ae. mutica with B chromosomes and T. aestivum × Ae. mutica nullisomic for wheat chromosome 5D with B chromosomes, in temperature regimes of 12° C. No asynapsis occurred in similar hybrids in the absence of Mutica B chromosomes at low temperatures. The low-temperature sensitive phase lies early in the pre-meiotic interphase. In this instance the Mutica B chromosomes are interacting with specific gene loci of the A chromosomes. Synaptic pairing has been observed between A and B chromosomes in Ae. mutica. A high frequency of pollen mother cells with twice the number of chromosomes was observed in hybrids in the presence of Mutica B chromosomes due to failure of spindle formation at the last pre-meiotic mitosis. Meiotic spindle irregularities occurred in hybrids containing Speltoides B chromosomes. Hybrids of Ae. speltoides + B's X Ae. mutica + B's displayed the mitotic and meiotic spindle abnormalities introduced by the presence of the B chromosomes of each parent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00320157
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  • 3
    Electronic Resource
    Electronic Resource
    A protoplast-to-tree system in Microcitrus based on protoplasts derived from a sustained embryogenic callus (1986)
    Springer
    Plant cell reports 5 (1986), S. 412-414 
    Details
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Adventitious embryos derived from a zygotic embryo in an in vitro cultured ovule of Microcitrus were transferred several times on solidified medium containing benzyladenine and 3-indoleacetyl-L-alanine to induce embryogenic callus. This callus was maintained for several years on medium devoid of growth regulators without losing its embryogenic capacity. Exposure of this callus to maceration enzymes led to protoplast suspensions. Purified protoplasts were plated in solid medium devoid of growth regulators. Somatic embryos were derived efficiently from individual protoplasts and most of these could be regenerated into mature trees bearing normal flowers and typical fruits. This system differs from the Citrus protoplast-to-tree system. In the latter embryogenic callus was derived from the nucellus of polyembryonic species while Microcitrus is monoembryonic and required hormone-induced callus formation from proliferating zygotic embryos.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00269629
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  • 4
    Electronic Resource
    Electronic Resource
    Suppression of somatic embryogenesis in Citrus cell cultures by extracellular proteins (1992)
    Springer
    Planta 186 (1992), S. 511-517 
    Details
    ISSN: 1432-2048
    Keywords: Cell culture (embryogenesis) ; Citrus (embryogenesis) ; Protein, extracellular ; Glycoprotein ; Somatic embryogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nucellar-derived cell cultures of sour orange (Citrus aurantium L.) proliferate as proembryogenic masses. By a change in the carbon source of the medium from sucrose to glycerol they are induced to undergo synchronous embryogenesis forming embryo initials that develop into globular embryos. The proembryogenic masses released glycoproteins to the medium. Exogenous addition of the glycoproteins to cells in glycerol-containing medium modified the course of embryo development in a dose-dependent manner. Addition of 20 μg · ml−1 of glycoproteins blocked embryogenesis and resulted in an accumulation of embryo initials. When glycoproteins were added to cultures containing advanced globularstage embryos further development was suppressed. The inhibitory component of the glycoproteins was found to be a family of polypeptides with apparent molecular masses of 53–57 kDa. While these proteins normally accumulated only in cultures of proembryogenic masses, they could be induced to accumulate in glycerol-containing medium by the addition of the glycoproteins. Thus, their accumulation was not a direct consequence of the type of growth medium used or the developmental state of the cultures. The results indicate that the 53-to 57 kDa glycoproteins could play a regulatory role in in-vitro embryogenesis in sour orange. The normal progression of embryo development appears to depend, in an obligatory manner, on the absence of these glycosylated extracellular proteins from the medium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00198030
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  • 5
    Electronic Resource
    Electronic Resource
    Production of flavanone-neohesperidosides in Citrus embryos (1989)
    Springer
    Plant cell reports 8 (1989), S. 391-394 
    Details
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Grapefruit (Citrus paradisi) tissue cultures were examined for qualitative and quantitative changes in flavanone-neohesperidoside content during somatic embryogenesis. Embryos cultured in vitro contain naringin and a rhamnosyl-transferase activity which is capable of rhamnosylating position 2 on the flavanone glucosides. Rhamnosylation is carried out only in embryos cultivated on solid medium but not in embryos grown in suspension cell cultures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00270076
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  • 6
    Electronic Resource
    Electronic Resource
    Transfer of stem rust seedling resistance from wild diploid einkorn to tetraploid durum wheat by means of a triploid hybrid bridge (1971)
    Springer
    Euphytica 20 (1971), S. 281-285 
    Details
    ISSN: 1573-5060
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Transfer of stem rust resistance from diploid wild einkorn, Triticum boeoticum, to susceptible Mindum and Spelmar, varieties of cultivated T. durum, was achieved by means of a triploid hybrid bridge and subsequent backcrossing to the tetraploid parent. Seedlings of the second hybrid generation segregated for resistance to race 14 of Puccinia graminis f.sp. tritici which was used as test race in this investigation. The F3 and F4 progenies included segregants which displayed seedling resistance also to races 17, 19, 21, 40, 53, 194, 222, 315 and 322. Since these were the same races which proved avirulent to the T. boeoticum donor but virulent to the T. durum recipients, it was concluded that the full pattern of resistance determined in the wild diploid parent of this cross was transferred to the tetraploid durum-like hybrid derivatives.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00056088
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