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  • 1
    Electronic Resource
    Electronic Resource
    Polyploidy and Aneuploidy in the Tamarillo, Cyphomandra betacea (Cav.) Sendt. (Solanaceae). (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 108 (1992), S. 0 
    Details
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The occurrence of spontaneous polyploidy was quantified in the tamarillo (Cyphomandra betacea [Cav.] Sendt.), a diploid (2n = 2x = 24) solanaceous fruit crop cultivated in New Zealand. Polyploids of this species were recognized by their small, almost seedless fruit, these types occurring at a frequency of 0.24 % in seedling orchards. Parallel spindles were seen on rare occasions during meiotic anaphase II in diploid tamarillos and were the probable cause of spontaneous polyploidy in this crop. Pollen volume and viability, seed number per fruit, seed weight, fruit size, stomatal length and guard cell chloroplast number were measured in diploids and polyploids. The polyploids typically showed the manifestation of the gigas effect, with thicker leaves and larger flowers. Pollen volume, stomatal length and guard cell chloroplast number also increased with higher ploidy. Pollen viability was markedly lower in the polyploids compared to the diploids and in combination with post-zygotic abnormalities caused a reduction in seed set and hence fruit size. Improvements in fertility and thus fruit size would be needed if the polyploids were to have commercial potential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1439-0523.1992.tb00112.x
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  • 2
    Electronic Resource
    Electronic Resource
    Light and electron microscope studies on pollen development in barley (Hordeum vulgare L.) grown under copper-sufficient and deficient conditions (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 11 (1988), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. Pollen development in copper-deficient barley plants is highly irregular resulting in low and variable pollen fertility. The main cause of this sterility was found to be the abnormal development of the tapetum which becomes expansionary and invasive as the pollen develops. The ultrastructure of both tapetum and microspores is different from that of control material with irregularities of exine deposition, endopolyploidy of tapetal nuclei and an alteration of organelle composition being correlated with low fertility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1988.tb01146.x
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  • 3
    Electronic Resource
    Electronic Resource
    Polyploidy and Flavonoid Synthesis in Briza media L. (1973)
    [s.l.] : Nature Publishing Group
    Nature 243 (1973), S. 87-88 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Fig. 1 Structures of flavonoids found in polyploids of B. media. I, vitexin, R1 = glucose, R2 = H; isovitexin, R1 = H, R2 = glucose. II, Orientin, R1= glucose, R2 = H; iso-orientin, R1 = H, R2 = glucose. Here we report on the leaf flavonoid patterns of artificially produced polyploids, differences ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/243087a0
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  • 4
    Electronic Resource
    Electronic Resource
    The cytology of the genus Briza L. (Gramineae) (1976)
    Springer
    Chromosoma 59 (1976), S. 73-81 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract B chromosomes have been found in populations of Briza spicata, B. elatior and both diploid and tetraploid races of B. media. In B. media the B chromosomes show non-Mendelian inheritance with an accumulation mechanism on the male side. At meiosis B chromosomes have no apparent effect on chiasma frequency in either B. media or B. elatior. F1 hybrids of B. media and B. elatior, in the absence of B chromosomes, have high chiasma frequencies but with the addition of B chromosomes there is a considerable reduction in the chiasma frequency of these plants. In the F1 hybrids there is a very marked dosage effect of B chromosome number on chiasma frequency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00327710
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  • 5
    Electronic Resource
    Electronic Resource
    The cytology of the genus Briza L. (Gramineae) (1975)
    Springer
    Chromosoma 49 (1975), S. 299-308 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Chromosome numbers have been determined and karyotypes studied in several species of the genus Briza L. Nuclear DNA amounts have also been determined for some of the species and show a considerable variation between the species. The evolution of the karyotypes, particularly that of B. minor, is discussed and an attempt made to relate nuclear DNA content to karyotypes, breeding systems and habit in the different species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00361072
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  • 6
    Electronic Resource
    Electronic Resource
    The cytology of the genus Briza L. (Gramineae) (1976)
    Springer
    Chromosoma 57 (1976), S. 81-93 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Meiosis has been studied in five European and four South American species of Briza. The various species have different chiasma frequencies and different patterns of chiasma localisation. Population studies show that there are significant differences in mean plant chiasma frequency between populations of B. maxima whereas B. media and B. spicata do not show interpopulation differences. B. media is shown to have diploid and autotetraploid races and the distribution of these chromosome races in Europe has been plotted. The South American species studied are all bivalent forming tetraploids and would therefore appear to have an allopolyploid origin. Interchange heterozygosity has been found in B. media and B. elatior, different populations of B. media have been shown to be heterozygous for different interchanges. These topics are discussed in relation to the regulation of recombination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00292951
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  • 7
    Electronic Resource
    Electronic Resource
    Studies on heteromorphic self-incompatibility systems: Physiological aspects of the incompatibility system of Primula obconica (1982)
    Springer
    Theoretical and applied genetics 61 (1982), S. 245-256 
    Details
    ISSN: 1432-2242
    Keywords: Primula obconica ; Heteromorphic self-incompatibility ; Pollen tube growth ; Pollen germination ; Pollen-stigma interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In Primula obconica, a species with a heteromorphic self-incompatibility system, the distinction between compatible and incompatible pollen tubes takes place on the stigma surface in thrum flowers, self tubes growing randomly over the papillar cells. No differences were seen between self and cross tube behaviour on the pin stigma surface, but self tubes were inhibited within the stigmatic tissue with differences in tube length evident after 24 h. The stigma surface bears a proteinaceous pellicle and binds the lectin Concanavalin A. Removal of the stigma removes the incompatibility barrier in mature gynoecia. Bud pollination shows that pollen tubes cannot grow in a normal manner on immature stigmas; the random growth of tubes over the stigma surface resembles that of mature thrum selfs. Fewer compatible tubes reach the style base of young gynoecia and smaller numbers of seeds are set than in mature flowers. Pin and thrum pollen grains germinate and grow in aqueous media, thrum tubes growing longer than pin. The presence of H3BO4 and CaCl2 in the growth medium promotes tube elongation and lengths equivalent to compatible styles can be obtained. The pollen grains have proteinaceous materials in their walls which diffuse out on moistening. Prolonged washing in aqueous media removes these materials but the incompatibility reaction remains unchanged. Thus the incompatibility reaction is between pollen tubes and stigmatic tissue and differs from the homomorphic, sporophytic system where pollen wall proteins elicit the incompatibility response.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00273782
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  • 8
    Electronic Resource
    Electronic Resource
    In situ hybridization in Actinidia using repeat DNA and genomic probes (1997)
    Springer
    Theoretical and applied genetics 94 (1997), S. 507-513 
    Details
    ISSN: 1432-2242
    Keywords: Key words Actinidia ; Kiwifruit ; Repeat sequence ; In situ hybridization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  In situ hybridization has been used to probe chromosome spreads of hexaploid Actinidia deliciosa (kiwifruit; 2n=6x=174) and tetraploid A. chinensis (2n=4x=116). When a species-specific repeat sequence, pKIWI516, was used, six hybridization sites were observed in some accessions of tetraploid A. chinensis and all of A. deliciosa. Southern analysis with the pKIWI516 probe revealed that there are two types of tetraploid A. chinensis. Genomic probes from diploid A. chinensis (2n=2x=58) did not differentiate the genomes of hexaploid A. deliciosa and tetraploid A. chinensis, irrespective of the presence or absence of blocking DNA. The results indicate that the genomes of polyploid Actinidia species are similar but not identical. The origin of A. deliciosa is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050444
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  • 9
    Electronic Resource
    Electronic Resource
    Quantitative analysis of diploid translocation heterozygotes: test of models and equations (1986)
    Springer
    Theoretical and applied genetics 71 (1986), S. 600-606 
    Details
    ISSN: 1432-2242
    Keywords: Translocation heterozygote ; Chromosome pairing models ; Equations ; Quantitative analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Equations have been derived for two different models of chromosome pairing and chiasmata distribution. The first model represents the normal condition and assumes complete synapsis of homologous bivalents and the arms of interchange quadrivalents. This is followed by a nonrandom distribution of chiasmata among bivalents and multivalents such that each bivalent or bivalent-equivalent always has at least one chiasma. Univalents occur only as part of a III, I configuration at diakinesis or metaphase I. The second model assumes that a hologenomic mutation is present in which all chromosomes of a genome are equally affected. Two different assumptions can be made for such a mutation, and both give the same results: (1) homologous or homoeologous chromosome arms may be randomly paired or unpaired, but synapsis always leads to a crossover; (2) homologous or homoeologous arms always pair, but chiasmata are randomly distributed among the arms. The meiotic configurations at diakinesis or metaphase I are the same for both assumptions. Meiotic configurations of normal diploid interchange heterozygotes show good agreement with numbers predicted by the equations for nonrandom chiasmata distribution among configurations. Inter-specific hybrids with supernumerary chromosomes produced meiotic configurations frequencies in agreement with predictions of equations for random chiasmata distribution, but a hybrid without supernumeraries fitted the nonrandom expectations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00264263
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  • 10
    Electronic Resource
    Electronic Resource
    Colchicine induced quadrivalent formation in Helianthus: evidence of ancient polyploidy (1983)
    Springer
    Theoretical and applied genetics 64 (1983), S. 219-222 
    Details
    ISSN: 1432-2242
    Keywords: Helianthus ; Colchicine ; Induced quadrivalents ; Cryptic polyploidy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The premeiotic treatment of microsporocytes of Helianthus annuus and H. laciniatus (x= 17) results in the formation of multivalent chromosome configurations at meiosis in these ‘diploid’ species. This is interpreted to mean that colchicine has disrupted the normal attachment of genomes to the nuclear membrane and allowed synapsis of the ancestral genomes, indicating the polyploid origin of these ‘diploid’ species. This technique should be of importance in generating intergenomal recombination in classical allopolyploid agronomic species because it could produce new genotypic combinations normally impossible to obtain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00303768
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