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  • 1
    Electronic Resource
    Electronic Resource
    Parental genomes are separated throughout the cell cycle in a plant hybrid (1991)
    Springer
    Chromosoma 101 (1991), S. 206-213 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The positions of the genomes originating from each parent were analysed in root-tip nuclei of the mature, sexual F1 hybrid plant Hordeum vulgare (barley) x Secale africanum (a wild rye). The two genomes of the hybrid were identified in both spread and sectioned material by non-radioactive DNA:DNA in situ hybridization using labelled total genomic DNA from one parent as a proble and unlabelled total genomic DNA from the other parent to block non-specific hybridization. Complete three-dimensional reconstructions of sets of labelled sections enabled detailed analysis of the position of the genomes at interphase. The parental genomes lay in various non-intermixed configurations, including lateral and concentric arrangements. On spread preparations, the two parental genomes were found to be spatially separated throughout the cell cycle; the genome originating from H. vulgare tended to be located more centrally than that from S. africanum. This results show that the nucleus is spatially organized above the level of the DNA and chromosome at the genome level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00365152
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  • 2
    Electronic Resource
    Electronic Resource
    Early post-pollination events in hexaploid wheat × maize crosses (1990)
    Springer
    Sexual plant reproduction 3 (1990), S. 70-76 
    Details
    ISSN: 1432-2145
    Keywords: Wheat ; Maize ; Hybridization ; Fertilization ; Karyogamy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cytological events in the first 12 h after pollination were studied in crosses between the hexaploid wheat genotype Chinese Spring and the maize genotype Seneca 60. A pollen tube was first observed in the embryo sac 4 h after pollination, and maize sperm nuclei were first observed in the embryo sac after 5 h. On 29 occasions two, and on 1 occasion three, pollen tubes penetrated the embryo sac. Four categories of aberration limiting the frequency of fertilization were identified: (1) in 20% of florets no pollen tube reached the embryo sac; (2) in at least 1.9% the pollen tube severely damaged the wheat egg cell and polar nuclei; (3) in 33% the maize sperm nuclei were not released from the pollen tube; and (4) in 16% the sperm nuclei were released into the embryo sac but failed to move to either of the wheat gametes. In the remaining 29% sperm nuclei were more often found in the egg cell than at the polar nuclei. The results suggest that karyogamy occurs with very high efficiency when a sperm nucleus reaches the egg cell, but with only about 50% efficiency when a sperm nucleus reaches the polar nuclei.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00189954
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  • 3
    Electronic Resource
    Electronic Resource
    Comparative responses of tetraploid wheats pollinated with Zea mays L. and Hordeum bulbosum L. (1994)
    Springer
    Theoretical and applied genetics 87 (1994), S. 673-680 
    Details
    ISSN: 1432-2242
    Keywords: Triticum turgidum ssp. durum ; Durum wheat x maize ; Durum wheat x H. bulbosum ; Pollen tubes ; Haploids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ten different tetraploid wheat (Triticum turgidum) genotypes were pollinated with maize (Zea mays). Fertilization was achieved in all ten genotypes and no significant difference in fertilization frequency between the tetraploid wheat genotypes was detected. A mean of 41.1% of pollinated ovaries contained an embryo. All these crosses were characterized by the elimination of the maize chromosomes, and the resulting embryos were haploids. Six of the tetraploid wheat genotypes were also pollinated with Hordeum bulbosum. Fertilization frequencies with H. bulbosum were much lower (mean=13.4%), and significant differences between the tetraploid wheat genotypes were detected. Observation of pollen tube growth revealed that part of the incompatibility reaction between tetraploid wheats and H. bulbosum was due to an effect similar to that of the Kr genes, namely pollen tube growth inhibition. These results indicate that pollinations with maize may have potential as a broad spectrum haploid production system for tetraploid wheats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222892
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  • 4
    Electronic Resource
    Electronic Resource
    Discrimination between closely related Triticeae species using genomic DNA as a probe (1990)
    Springer
    Theoretical and applied genetics 79 (1990), S. 721-728 
    Details
    ISSN: 1432-2242
    Keywords: Genomic probe ; Blocking DNA ; Chemiluminescence ; Species identification ; Cereals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Labelled total genomic DNA was used as a probe in combination with blocking DNA to discriminate between taxonomically closely related species in the genera Hordeum and Secale. Discrimination was possible both by Southern hybridization to size-fractionated restriction enzyme digests of genomic DNA and by in situ hybridization to chromosome preparations. To distinguish between two species (e.g. H. vulgare and H. bulbosum), genomic DNA from one species was used as the labelled probe, while unlabelled DNA from the other species was applied at a much higher concentration as a block. The blocking DNA presumably hybridized to sequences in common between the block and the labelled probe, and between the block and DNA sequences on the membrane or chromosomes in situ. If so, mainly species-specific sequences would remain as sites for probe hybridization. These species-specific sequences are dispersed and represent a substantial proportion of the genome (unlike many cloned, species-specific sequences). Consequently, rapid nonradioactive methods detected probe hybridization sites satisfactorily. The method was able to confirm the parentage of hybrid plants. It has potentially wide application in plant breeding for the detection of alien DNA transfer, and it can be easily adapted to many species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224236
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  • 5
    Electronic Resource
    Electronic Resource
    Durum wheat haploid production using maize wide-crossing (1994)
    Springer
    Theoretical and applied genetics 89 (1994), S. 559-566 
    Details
    ISSN: 1432-2242
    Keywords: Haploids ; Wide hybridization ; Durum wheat ; Maize ; Embryo culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract While anther culture or pollinations with Hordeum bulbosum have provided suitable methods for haploid production in bread wheat, they have been largely unsuccessful in durum wheat. Pollinations with maize were used in an attempt to produce haploid seedlings and, from these, fertile doubled haploids of durum wheats. Moreover, the effect of various concentrations and combinations of a synthetic auxin, 2, 4-dichlorophenoxyacetic acid (2,4-D), kinetin, and an ethylene inhibitor, silver nitrate (AgNO3), on embryo recovery were also investigated. Haploid seedlings were recovered from Triticum turgidum ssp. turgidum cv ‘Rampton Rivet’ pollinated with maize following in-vivo treatment of ovaries with 2,4-D for 2 weeks and subsequent embryo culture. The recovery of haploid seedlings from T. turgidum ssp. durum cv. ‘Wakona’ pollinated with maize necessitated the addition of AgNO3, to the 2,4-D treatment. Overall, haploid seedlings were produced in 1.7% and 3.3% of pollinated florets for “Rampton Rivet” and “Wakona” respectively. The success of the present work represents a significant breakthrough for haploid production in durum wheats. Wide hybridization with maize followed by in-vivo treatment of ovaries with 2,4-D alone, or in combination with AgNO3, may provide a widely-applicable method of haploid production in tetraploid wheats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222448
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  • 6
    Electronic Resource
    Electronic Resource
    The fate of recombinant chromosomes and genome interaction in Nicotiana asymmetric somatic hybrids and their sexual progeny (1994)
    Springer
    Theoretical and applied genetics 89 (1994), S. 488-497 
    Details
    ISSN: 1432-2242
    Keywords: Nicotiana plumbaginifolia ; N. sylvestris Asymmetric somatic hybrids ; Meiosis ; Sexual progeny Intergenomic translocations ; In-situ hybridization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Genomic in-situ hybridization (GISH) was used to monitor the behaviour of parental genomes, and the fate of intergenomic chromosome translocations, through meiosis of plants regenerated from asymmetric somatic hybrids between Nicotiana sylvestris and N. plumbaginifolia. Meiotic pairing in the regenerants was exclusively between chromosomes or chromosome segments derived from the same species. Translocation (recombinant) chromosomes contained chromosome segments from both parental species, and were detected at all stages of meiosis. They occasionally paired with respectively homologous segments of N. sylvestris or N. plumbaginifolia chromosomes. Within hybrid nuclei, the meiotic division of N. plumbaginifolia lagged behind that of N. sylvestris. However, normal and recombinant chromosomes were eventually incorporated into dyads and tetrads, and the regenerants were partially pollen fertile. Recombinant chromosomes were transmitted through either male or female gametes, and were detected by GISH in sexual progeny obtained on selfing or backcrossing the regenerants to N. sylvestris. A new recombinant chromosome in one plant of the first backcross generation provided evidence of further chromosome rearrangements occurring at, or following, meiosis in the original regenerants. This study demonstrates the stable incorporation of chromosome segments from one parental genome of an asymmetric somatic hybrid into another, via intergenomic translocation, and reveals their transmission to subsequent sexual progeny.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225385
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  • 7
    Electronic Resource
    Electronic Resource
    Cytotaxonomic studies of Eastern MediterraneanVicia species (Leguminosae) (1991)
    Springer
    Plant systematics and evolution 177 (1991), S. 221-234 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; Leguminosae ; Papilionoideae ; Vicieae ; Vicia ; Vetch ; chromosome number ; DNA amount ; microdensitometry ; cytotaxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Collected material of rare and newVicia spp. was investigated from a cytotaxonomic point of view. Nineteen species were examined in total. The study includes 14 novel chromosome counts and measurements of DNA amount, as well as a comparison of chromosome morphology between species. The results of the cytological study support to an extent a recent taxonomical revision of subgenusVicia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00937959
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  • 8
    Electronic Resource
    Electronic Resource
    Parental genome separation and asynchronous centromere division in interspecific F1 hybrids inLathyrus (1994)
    Springer
    Chromosome research 2 (1994), S. 383-397 
    Details
    ISSN: 1573-6849
    Keywords: centromeres ; genome separation ; hybrids ; Lathyrus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chromosomes were studied in root-tip metaphase cells of several F1 interspecificLathyrus hybrids including:L. hirsutus × L. cassius (H × C),L. cassius × L. hirsutus (C × H),L. cassius × L. odoratus (C × O), and their parents, all with 2n = 2x = 14. Two types of morphologically distinct centromeres were identified in the hybrids on the basis of the degree of contraction of the primary constriction. At least 12 well-defined centromeres were seen in all cells ofL. hirsutus, L. cassius andL. odoratus, and about 80% of cells had 14. The hybrids were more variable than the species. H × O contained between six and 14 welldefined centromeres, while cells of H × C, C × H and C × O all had seven well-defined and seven weakly defined centromeres. These were used as markers to plot their spatial disposition in two dimensions on metaphase spreads. In H × C, C × H and C × O the two types of centromeres showed a significant tendency to occupy two spatially distinct and concentrically arranged domains on the metaphase plate (P 〈 0.005). Owing to shortage of material subsequent work was restricted to H × C and C × H. Six or seven chromosomes of one parental genome were selectively labelled byin situ hybridization using biotinylated total genomic DNA from either parent as a probe. Moreover, there was a very strong correlation between centromere type and genomic origin (P 〈 0.001). Clearly the tendency for spatial segregation of parental genomes into concentrically arranged domains previously noted in several F1 interspecific sexual hybrids between grasses can occur strongly in dicots. The present work onLathyrus also included the first comparative study of the spatial arrangement of parental genomes in reciprocal hybrids. Significantly,L. cassius chromosomes tended to surroundL. hirsutus chromosomes in both H × C and C × H. Thus, the polarity of concentric parental genome separation was not determined as a maternal effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01552798
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