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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
    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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  • 3
    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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  • 4
    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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  • 5
    Electronic Resource
    Electronic Resource
    Resistance to Brevicoryne brassicae in horticultural brassicas (1996)
    Springer
    Euphytica 88 (1996), S. 85-96 
    Details
    ISSN: 1573-5060
    Keywords: Brevicoryne brassicae ; cabbage aphid ; Brassica oleracea ; brassicas ; host plant resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A wide range of cultivated brassica accessions including broccoli, Brussels sprouts, Chinese cabbage, cauliflower, collard, kale and swede material was tested against the cabbage aphid, Brevicoryne brassicae, at HRI, Wellesbourne in the field and laboratory in both 1992 and 1993. In the field, B. brassicae attack was assessed as the proportion of infested plants and the numbers of aphid colonies present. In the laboratory, aphid performance was measured in terms of the pre-reproductive and reproductive period, population increase, and insect mortality. Interpretation of the data was facilitated by plotting sorted accession means against normal order statistics. This statistical approach indicated the spread of variation amongst the accessions and permitted identification of extremes. Partial levels of antixenosis resistance were discovered in red brassicas. Glossy accessions of cabbage and cauliflower possessed antixenosis and antibiosis resistance that lasted throughout the season of crop growth in the field. Other accessions were shown to withstand aphid attack and therefore possessed tolerance. The laboratory studies provided information on mechanisms of antibiosis resistance. The potential value of the different sources of resistance is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00032439
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  • 6
    Electronic Resource
    Electronic Resource
    The impact of some agronomic factors on the variability of potato tuber size distribution (1993)
    Springer
    Potato research 36 (1993), S. 237-245 
    Details
    ISSN: 1871-4528
    Keywords: coefficient of variation ; numbers of tubers ; uniformity ; Solanum tuberosum L
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Using data from a wide range of experiments, the effects of some agronomic factors on the variability of the tuber size distribution were calculated. The factors studied were nitrogen (N), phosphorus (P), potassium (K), seed-tuber planting density, physiological age, date of harvest, seed-tuber weight, irrigation, cultivar and site of production. There were significant effects of N, date of harvest, cultivar and site of production on the variability of the tuber size distribution measured as the coefficient of variation (CV) of tuber size. The CV increased with higher levels of aplied N and with later harvesting. The largest effect, but one that was unquantifiable, was that of site of production. These results demonstrate that the uniformity of tuber size distribution can vary and suggest that work to understand the reasons for this would be valuable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02360532
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  • 7
    Electronic Resource
    Electronic Resource
    The effect of some environmental factors on potato tuber numbers (1997)
    Springer
    Potato research 40 (1997), S. 297-306 
    Details
    ISSN: 1871-4528
    Keywords: light ; temperature ; stolon growth medium ; below ground nodes ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Five experiments studied the effects of shading, temperature and stolon growth medium on stolon and tuber formation. The lowest numbers of stolons and tubers were produced at the higher and lower nodes. Numbers of primary stolons and tubers were relatively stable across nodes and treatments and variation in total numbers was largely due to changes in numbers of lateral and branch stolons. In the field, 70% shading reduced numbers of stolons and tubers by reducing lateral and branch stolons, while in hydroponics, 45% shading and temperatures at initiation had no effect on tuber numbers. In both environments later planting tended to reduce numbers of stolons and tubers. There were large effects of the physical environment, with compost producing three times as many tubers as dry vermiculite. The potential number of tubers may be determined by the number of stolons and the environmental conditions affecting stolon formation and development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02358011
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