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  • 1
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR-In recent months, controversy has arisen internationally over the conservation and availability of plant genetic resources, the genetic diversity of primitive varieties of crop plants and related wild species upon which future crop improvement programmes will depend. Much of the controversy ...
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Plant systematics and evolution 137 (1981), S. 57-61 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Chenopodiaceae ; Spinacia ; S. turkestanica ; S. tetrandra ; Reproduction ; multigermicity ; seedball ; dioecy ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The presence of multigerm seedballs in the chenopodiacious genusSpinacia is noted. In the wild, colonising, and “weedy” dioecious species,S. turkestanica andS. tetrandra, the distribution of a multigerm seedball could effectively overcome the problem posed by isolation of the sexes. The hypothesis is tested assessing the extent of intra-seedball progeny hybridisations and seed production in the two wild species. The success in seed production by intra-seedball progeny crosses suggests that the distribution of such seedball progeny groups permits not only a percentage survival under isolation of these dioecious plants, but also the colonisation of areas outside that of the parent populations.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Genetic resources and crop evolution 44 (1997), S. 523-532 
    ISSN: 1573-5109
    Keywords: Brassica rapa ; Brassica napus ; electrophoresis ; genetic diversity ; isozyme analysis ; regenerationprocedure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This investigation was conducted to assess changes in the genetic structure of two varieties of two species of annual Brassica. Seeds of B. napus cv. “Topas” and B. rapa “Broccoletto” were sent to nine research institutes in different geographical areas of Europe for regeneration. The multiplied material was sent back after one year of regeneration and analysed electrophoretically. The original populations of each species and their multiplied samples were stained for 12 different enzymes, of which 4 were found to be polymorphic (DIA, SKD, GPI and PER). It was possible to detect considerable differences in isozyme patterns in B. napus and allelic frequencies in B. rapa, both within and between populations. When the original population was compared with the regenerated samples, the Chi-square homogeneity test for all pairwise comparisons revealed distinctness with a 99% probability for B. napus and 95% probability for B. rapa with one or more of the enzyme systems examined. Furthermore, the average of gene diversity analysis (Nei, 1973) revealed that some regenerated populations have less while others have increased genetic variation compared with the original population. These observations indicated that the frequencies were non-random and considerable shifts in genetic diversity have occurred during multiplication. In addition, different regeneration procedures have caused the fixation of certain alleles.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 28 (1979), S. 685-696 
    ISSN: 1573-5060
    Keywords: Solanum sucrense ; taxonomy ; crossability ; field studies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Two theories for the origin of the Bolivian weed potato species Solanum sucrense Hawkes have been tested. The first was that it had an allopolyploid origin as a hybrid of the cultivated tetraploid S. tuberosum ssp. andigena (Juz. et Buk.) Hawkes with the wild/weed tetraploid cytotype of S. oplocense Hawkes. The second hypothesis postulated that it was a cross of the weed diploid species S. sparsipilum (Bitt.) Juz. et Buk. with S. oplocense. Synthetic hybrids of S. tuberosum ssp. andigena x S. oplocense and of S. sparsipilum x S. oplocense have been compared morphologically with S. sucrense accessions. Their crossability has also been investigated. The crossability and morphological studies strongly suggested that the former hypothesis was the more likely. This was borne out by observations made on the 1974 University of Birmingham Expedition when segregating populations of S. sucrense and S. oplocense were collected growing with feral S. tuberosum ssp. andigena. The evidence from this study indicates that the S. tuberosum ssp. andigena x S. oplocense hybrid has formed the basis of the S. sucrense gene pool. It is suggested that this hybridogenic taxon be maintained under the name Solanum x sucrense. The clarification of the taxonomic relationships of these three species will be of interest to Globodera resistance breeders, in view of the fact that these taxa are resistant to various pathotypes of the golden nematode.
    Type of Medium: Electronic Resource
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