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  • 1
    Electronic Resource
    Electronic Resource
    Constraints on mutability in a multiallelic gene family (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 732-740 
    Details
    ISSN: 1432-1432
    Keywords: Mutation ; Nearest ; neighbor effects ; DNA structure ; Brassica incompatibility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A highly variable family of related DNA sequences was examined in order to determine the effect of local sequence environment on substitution mutation; 29 sequences from the Brassica self-incompatibility gene family, which possess a high level of nonsynonymous mutations, were aligned and grouped according to their similarity and function. The level and distribution of substitution mutations were calculated. A nonrandom distribution of sequence variation was observed along the sequences. The effect of neighbor biases and structural and thermodynamic measures were then compared in the absence of strong codon conservation. Biases were observed in the rates of substitution of the same base pair in different local sequence environments. The effect of the 5′ neighbor was such that nucleotide A or C was associated with more mutations than G or T. There were significant interactions of certain dinucleotides with the frequency of mutation. Sequence-dependent measures of helical stability, intrinsic curvature, components of curvature, and stacking interactions were calculated for each sequence. Decreased helical stability was found to be associated with increased mutation. The compound measure of curvature, calculated according to the “wedge” model, showed little association with mutation. However, the components of increased wedge angle and decreased twist both showed an association with increased mutation. A small effect of A-type DNA stacking was found to be associated with mutated bases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00173153
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  • 2
    Electronic Resource
    Electronic Resource
    Relationships between water-use traits and photosynthesis in Brassica oleracea resolved by quantitative genetic analysis (2005)
    Berlin, Germany : Blackwell Verlag GmbH
    Plant breeding 124 (2005), S. 0 
    Details
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The genetic control of water-use and photosynthetic traits in Brassica oleracea is resolved by genetic analysis of quantitative trait loci (QTL). Variations in leaf conductance, photosynthetic assimilation rate, leaf thickness and leaf nitrogen content were assessed in a segregating population of F1-derived doubled haploid (DH) B. oleracea lines. In addition, stable carbon isotope ratios in leaf organic material were used as a surrogate measure of plant water-use efficiency. Analysis of an existing linkage map for the population revealed significant QTL on seven linkage groups. Single significant QTL explained between 3.4% and 36.6% of the phenotypic variance in each of the traits measured. The locations of QTL for several traits were found to coincide in a physiologically meaningful way; stable carbon isotope discrimination had QTL co-locating with leaf level water-use efficiency, photosynthetic capacity with leaf thickness and nitrogen content and stomatal density with leaf thickness. Taken together, these results suggest that single genes or clusters of genes at these loci may have an influence on the expression of physiologically related traits controlling water-use and photosynthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1439-0523.2005.01164.x
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  • 3
    Electronic Resource
    Electronic Resource
    Ultrastructural Observations on the Platelets of the Arabian Tahr (Hemitragus jayakari) (2002)
    Berlin, Germany : Blackwell Verlag GmbH
    Anatomia, histologia, embryologia 31 (2002), S. 0 
    Details
    ISSN: 1439-0264
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The ultrastructure of platelets was studied in specimens of peripheral blood from 18 healthy adult Arabian tahrs (Hemitragus jayakari). The platelets were characterized by their extreme polymorphism. The number of alpha granules, typically one to six per cell, was considerably less than that reported for most animal platelets. Similar to humans, the platelets of the Arabian tahr had nucleoids within the alpha granules. However, nucleoids were not a consistent finding. One or more electron-dense granules, most commonly contained within clear vesicles, was commonly observed. A unique feature was the lack of an open canalicular system, which is considered a hallmark feature of this cell type in most mammalian and reptilian platelets.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1439-0264.2002.00379.x
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  • 4
    Electronic Resource
    Electronic Resource
    RFLP and RAPD markers linked to the rosy leaf curling aphid resistance gene (Sd1) in apple (1997)
    Springer
    Theoretical and applied genetics 94 (1997), S. 528-533 
    Details
    ISSN: 1432-2242
    Keywords: Key words Apple ; Dysaphis devecta ; Insect resistance ; Marker-assisted selection ; Molecular markers ; Plant breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Sd 1 is a dominant gene for resistance to biotypes 1 and 2 of the rosy leaf curling aphid, Dysaphis devecta Wlk., which can cause economic damage to apple trees. This report describes the identification of three RFLP and four RAPD markers linked to Sd 1 in a cross between the D. devecta susceptible variety ‘Prima’ (sd 1 sd 1) and the resistant variety ‘Fiesta’ (Sd 1 sd 1). Potted trees were artificially infested in the glasshouse, and the ratio of resistant:susceptible plants supported the hypothesis that the resistance was under the control of a single dominant gene. The position of the gene was mapped to a single locus on a ‘Fiesta’ chromosome, within 2 cM of three tightly linked RFLP markers (MC064a, 2B12a and MC029b); the four RAPD markers were located further away (between 13 and 46 cM). This is the first report of molecular markers for an aphid resistance gene in tree fruit crops. The potential application of these markers in a marker-assisted resistance breeding programme is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050447
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  • 5
    Electronic Resource
    Electronic Resource
    Aligning male and female linkage maps of apple (Malus pumila Mill.) using multi-allelic markers (1998)
    Springer
    Theoretical and applied genetics 97 (1998), S. 60-73 
    Details
    ISSN: 1432-2242
    Keywords: Key wordsMalus pumila Mill ; Molecular linkagemap ; Marker-assisted selection ; Fruit tree breeding ; Outbred progeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Linkage maps for the apple cultivars ‘Prima’ and ‘Fiesta’ were constructed using RFLP, RAPD, isozyme, AFLP, SCAR and microsatellite markers in a ‘Prima’בFiesta’ progeny of 152 individuals. Seventeen linkage groups, putatively corresponding to the seventeen haploid apple chromosomes, were obtained for each parent. These maps were aligned using 67 multi-allelic markers that were heterozygous in both parents. A large number of duplicate RFLP loci was observed and, in several instances, linked RFLP markers in one linkage group showed corresponding linkage in another linkage group. Distorted segregation was observed mainly in two regions of the genome, especially in the male parent alleles. Map positions were provided for resistance genes to scab and rosy leaf curling aphid (Vf and Sd 1, respectively) for the fruit acidity gene Ma and for the self-incompatibility locus S. The high marker density and large number of mapped codominant RFLPs and some microsatellite markers make this map an ideal reference map for use in other progenies also and a valuable tool for the mapping of quantitative trait loci.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050867
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  • 6
    Electronic Resource
    Electronic Resource
    Introgression of the Vf source of scab resistance and distribution of linked marker alleles within the Malus gene pool (1999)
    Springer
    Theoretical and applied genetics 99 (1999), S. 1039-1046 
    Details
    ISSN: 1432-2242
    Keywords: Key words Apple ; Scab resistance ; Introgression ; Vf gene ; DNA markers ; Linkage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A chromosomal region originating from Malus floribunda 821 confers Vf scab resistance to many isolates of Venturia inaequalis. Twelve DNA markers located in this region were used to scan the equivalent of 31 cM in 98 Malus accessions. This allowed a molecular diagnosis of a source of resistance in apple germplasm with the aid of pedigree information, and in the context of a limited marker survey representing other chromosomes. At least five marker alleles were present in all scab-resistant breeding selections or varieties arising from M. floribunda. The validity of findings based on RAPD markers was confirmed with SCAR assays and Southern-hybridisation experiments. The order of markers determined in previous mapping studies was confirmed and sets of recombinants identified that establish reliable fine-mapping orders within 0.7 cM of the resistance locus. None of the marker alleles were present in the accessions that are either susceptible or possess weak polygenic resistance to scab. The presence of some alleles corresponding to those present at least 5.3 cM from Vf in M. floribunda was detected in some accessions. Other major sources of scab resistance do not appear to possess alleles in common with the Vf region, which will simplify future allelism tests. The results are discussed in the context of the introgression of resistance loci together with marker-assisted selection. The use of breeding pedigrees to assist in fine-scale mapping and map-based cloning is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220051412
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  • 7
    Electronic Resource
    Electronic Resource
    Multiple field and glasshouse assessments increase the reliability of linkage mapping of the Vf source of scab resistance in apple (1998)
    Springer
    Theoretical and applied genetics 96 (1998), S. 699-708 
    Details
    ISSN: 1432-2242
    Keywords: Key words Malus ; Apple ; Venturia ; Scab resistance ; Linkage mapping ; Cluster analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Apple scab, caused by the fungus Venturia inaequalis (Cke.) Wint., is an important disease in commercial apple production. A mapping population of 155 individuals, derived from a cross between the apple varieties ‘Prima’ (resistant)בFiesta’ (susceptible), was scored for response to the disease in replicated field and glasshouse trials throughout Europe. Twenty data sets were selected and cluster analysis was used to form a consensus score for the population fitting a 1 : 1 segregation ratio of resistance:susceptibility. The progeny were scored with molecular markers. A detailed map covering 54 cM of the ‘Prima’ linkage group containing the Vf gene for scab resistance was constructed using 24 molecular markers linked to the resistance gene. One isoenzyme marker (Pgm-1), six RFLP markers and 17 RAPD markers formed a linkage group with the consensus measure of resistance to scab. Four marker bridges were established with the corresponding ‘Fiesta’ linkage group with additional markers (one isozyme, one RFLP, three RAPD and one AFLP). A low chi-square value indicated a good fit of the marker ordering, which was in close agreement with previously reported linkage positions for some of the markers and Vf. Differences were observed in the ability of different scoring methods to resolve susceptible and resistant classes. The results obtained for the consensus classification of resistance to scab for the population may suggest the presence of virulent inocula at some sites, which could overcome the Vf gene for resistance. The consequences of relying on individual scoring occasions for studying Vf scab resistance are discussed in the context of linkage analysis, conventional breeding selection, and marker-assisted selection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050791
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  • 8
    Electronic Resource
    Electronic Resource
    An integrated AFLP and RFLP Brassica oleracea linkage map from two morphologically distinct doubled-haploid mapping populations (2000)
    Springer
    Theoretical and applied genetics 100 (2000), S. 75-81 
    Details
    ISSN: 1432-2242
    Keywords: Key words Brassica oleracea ; Integrated map ; Molecular markers ; Doubled-haploid ; Comparative mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Genetical maps of molecular markers in two very different F1-derived doubled-haploid populations of Brassica oleracea are compared and the first integrated map described. The F1 crosses were: Chinese kale×calabrese (var. alboglabra×var. italica) and cauliflower×Brussels sprout (var. botrytis×var. gemmifera). Integration of the two component maps using Joinmap v.2.0 was based on 105 common loci including RFLPs, AFLPs and microsatellites. This provided an effective method of producing a high-density consensus linkage map of the B. oleracea genome. Based on 547 markers mapping to nine linkage groups, the integrated map covers a total map length of 893 cM, with an average locus interval of 2.6 cM. Comparisons back to the component linkage maps revealed similar sequences of common markers, although significant differences in recombination frequency were observed between some pairs of homologous markers. Map integration resulted in an increased locus density and effective population size, providing a stronger framework for subsequent physical mapping and for precision mapping of QTLs using substitution lines.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050011
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  • 9
    Electronic Resource
    Electronic Resource
    A molecular approach to the identification of S-alleles in Brassica oleracea (1994)
    Springer
    Sexual plant reproduction 7 (1994), S. 203-208 
    Details
    ISSN: 1432-2145
    Keywords: Brassica oleracea ; Self-incompatibility ; S alleles ; PCR identification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A molecular technique for the identification of S-alleles involved in self-incompatibility has been used to analyse the S-allele reference collection of Brassica oleracea. The reference collection contains nearly 50 different lines each with a different S-allele present in the homozygous state. The technique consists of amplifying by the polymerase chain reaction (PCR) sequences belonging to the S multigene sequence family using a single pair of conserved primers. PCR products are then analysed further by digestion with six restriction enzymes followed by gel electrophoresis of the digestion products. A simple method of estimating the band sizes of the digestion products is described. The S-locus-related sequences can be distinguished from S-locus glycoprotein and S-receptor kinase genes by the restriction patterns. Furthermore, with any one restriction enzyme, several alleles showed the same restriction pattern. Alleles could therefore be grouped together. With two exceptions, each member of the S-allele reference collection showed a unique set of restriction patterns. Investigation of the exceptions using pollen tube growth tests showed that these accessions represented duplications within the collection. This technique therefore provides a simple and useful method for identifying different S-alleles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00232738
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  • 10
    Electronic Resource
    Electronic Resource
    Quantitative genetic analysis and comparison of physical and sensory descriptors relating to fruit flesh firmness in apple (Malus pumila Mill.) (2000)
    Springer
    Theoretical and applied genetics 100 (2000), S. 1074-1084 
    Details
    ISSN: 1432-2242
    Keywords: Key words Apple ; Fruit ; Firmness ; Texture ; QTL analysis ; Genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Texture is a major component of consumer preference for eating-quality in apple. A quantitative genetic analysis of traits associated with fruit-flesh firmness was carried out. This was based on segregation in an unselected mapping population replicated at six sites and harvested over 2 years. Different methods of assessment were compared, and a principal components analysis carried out. Instrumental measures used were Magness-Taylor penetrometer readings, stiffness by acoustic resonance, and a range of sensory descriptors assessed by a trained panel. There were good correlations between some measures, although stiffness was poorly correlated. Whilst genotype by environment effects were large, significant effects were attributable to the genotype, and these were used to detect QTLs. Significant QTLs were detected on seven linkage groups, with large effects on linkage groups L01, L10 and L16. Whilst there was a poor correlation between acoustic stiffness and other measures, the significant and suggestive QTL detected for stiffness on linkage group L10 did represent a subset of significant QTLs detected for the penetrometer measure. The use of sensory assessment proved valuable in detecting QTLs representing different attributes of fruit texture. The possibility of interaction between significant QTLs for fruit texture and other strongly selected traits such as scab resistance and fruit acidity is addressed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220051389
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