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  • 1
    Electronic Resource
    Electronic Resource
    Unexpected DNA content in the endosperm of Cupressus dupreziana A. Camus seeds and its implications in the reproductive process (1998)
    Springer
    Sexual plant reproduction 11 (1998), S. 148-152 
    Details
    ISSN: 1432-2145
    Keywords: Key words Cupressus dupreziana ; DNA content ; Endosperm ; Reproduction ; Flow cytometry ; Gymnosperm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Nuclear DNA content of embryo and endosperm from mature and immature Cupressus dupreziana A. Camus seeds was estimated using laser flow cytometry. Relative DNA content of endosperm nuclei corresponded to four ploidy levels: 2C, 4C, 6C and 8C. The embryo nuclei invariably exhibited a diploid pattern. In all endosperm tissue analyzed no haploid nucleus was found. This is problematic since, in gymnosperms, endosperm and female gametes originate from one functional haploid megaspore produced by meiosis. The possible origin and derivation of C. dupreziana endosperm are discussed in light of previous results concerning the two other Mediterranean cypresses, C. sempervirens and C. atlantica.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004970050132
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Unreduced diploid nuclei in Cupressus dupreziana A. Camus pollen (2000)
    Springer
    Theoretical and applied genetics 101 (2000), S. 574-579 
    Details
    ISSN: 1432-2242
    Keywords: Key words 2n pollen ; Cupressus dupreziana ; Gymnosperms ; Flow cytometry ; Reproduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Size and DNA content of pollen of Cupressus dupreziana A. Camus, a highly endangered Mediterranean conifer, were assessed by cytomorphological observations and flow cytometric analyses and then compared to C. sempervirens L. pollen. Mature C. dupreziana pollen was composed of two uninucleated types of pollen grains differing in size. Around 35% of the grains exhibited a size similar to C. sempervirens pollen, while 65% exhibited a larger diameter. However only one peak of fluorescence was detected by flow cytometry. DNA content of C. dupreziana pollen was twice the DNA content of C. sempervirens pollen. Comparison of DNA contents of mature and germinating pollen revealed that mature pollen of both species were arrested in the G2 phase. Comparison with the DNA content of somatic tissue (2C) provided evidence for the production of unreduced pollen in C. dupreziana. This unexpected feature in gymnosperms is discussed in terms of reproductive strategy of this species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220051518
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Flow cytometric evidence for multiple ploidy levels in the endosperm of some gymnosperm species (1997)
    Springer
    Theoretical and applied genetics 94 (1997), S. 865-870 
    Details
    ISSN: 1432-2242
    Keywords: Key words Gymnosperms ; Ploidy ; Endosperm ; Embryo ; Flow cytometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Considered to be haploid tissue, the endosperm of coniferous trees has been extensively used by forest geneticists. Using laser flow cytometry, we show that endosperm ploidy level depends on the systematic position. The Abies, Cedrus and Pinus species tested exhibited uniform haploid endosperm compared to the diploid DNA content of the corresponding embryo. Endosperm of Cupressaceae contained multiple ploidy levels: Cupressus arizonica, Juniperus oxycedrus and Thuja orientalis endosperms exhibited a mixture of haploid–diploid nuclei, while C. atlantica and C. sempervirens endosperms contained six ploidy levels: 1C, 2C, 3C, 4C, 5C and 6C. Physiological and genetic implications of this original feature are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050488
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    Paper (German National Licenses)
    Fulltext
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