scholarly journals Efficient marker-based recurrent selection for multiple quantitative trait loci

2000 ◽  
Vol 75 (3) ◽  
pp. 357-368 ◽  
Author(s):  
F. HOSPITAL ◽  
I. GOLDRINGER ◽  
S. OPENSHAW
Keyword(s):  
Molecular Markers ◽  
Quantitative Trait Loci ◽  
Population Size ◽  
Quantitative Trait ◽  
Recurrent Selection ◽  
Selection Procedures ◽  
Mean Frequency ◽  
Trait Loci ◽  
The Mean ◽  
Selection For

We studied the efficiency of recurrent selection based solely on marker genotypes (marker-based selection), in order to increase favourable allele frequency at 50 previously detected quantitative trait loci (QTLs). Two selection procedures were investigated, using computer simulations: (1) Truncation Selection (MTS), in which individuals are ranked based on marker score, and best individuals are selected for recombination; and (2) QTL Complementation Selection (QCS), in which individuals are selected such that their QTL composition complements those individuals already selected. Provided QTL locations are accurate, marker-based selection with a population size of 200 was very effective in rapidly increasing frequencies of favourable QTL alleles. QCS methods were more effective than MTS for improving the mean frequency and fixation of favourable QTL alleles. Marker-based selection was not very sensitive to a reduction in population size, and appears valuable to optimize the use of molecular markers in recurrent selection programmes.

The construction of a substitution library of recombinant backcross lines in Brassica oleracea for the precision mapping of quantitative trait loci

Genome ◽  
1996 ◽  
Vol 39 (3) ◽  
pp. 558-567 ◽  
Author(s):  
L. D. Ramsay ◽  
D. E. Jennings ◽  
M. J. Kearsey ◽  
D. F. Marshall ◽  
E. J. R. Bohuon ◽  
...  
Keyword(s):  
Molecular Markers ◽  
Quantitative Trait Loci ◽  
Brassica Oleracea ◽  
Quantitative Trait ◽  
Near Isogenic Lines ◽  
Substitution Lines ◽  
Trait Loci ◽  
Donor Chromosome ◽  
Selection For ◽  
Very High

The currently available methods for locating quantitative trait loci (QTLs) and measuring their effects in segregating populations lack precision unless individual QTLs have very high heritabilities. The use of recombinant backcross lines containing short regions of donor chromosome introgressed into a constant recipient background permits QTLs to be located with greater precision. The present paper describes the use of molecular markers to introgress defined short regions of chromosome from a donor doubled haploid calabrese line of Brassica oleracea (var. italica) into a recipient short generation variety (Brassica oleracea var. alboglabra). We demonstrate that in just two or three generations of backcrossing, combined with selection for mapped molecular markers, the generation of a library of recombinant backcross lines is feasible. The possible use and refinement of these lines are discussed. Key words : backcrossing, Brassica oleracea, introgression, molecular markers, near-isogenic lines, QTL mapping, recombinant backcross lines, substitution lines.

scholarly journals Bayesian Model Selection for Genome-Wide Epistatic Quantitative Trait Loci Analysis

Genetics ◽  
2005 ◽  
Vol 170 (3) ◽  
pp. 1333-1344 ◽  
Author(s):  
Nengjun Yi ◽  
Brian S. Yandell ◽  
Gary A. Churchill ◽  
David B. Allison ◽  
Eugene J. Eisen ◽  
...  
Keyword(s):  
Quantitative Trait Loci ◽  
Model Selection ◽  
Quantitative Trait ◽  
Bayesian Model ◽  
Bayesian Model Selection ◽  
Genome Wide ◽  
Trait Loci ◽  
Selection For

Investigating temperament traits in cattle for quantitative trait loci (QTL) identification

2002 ◽  
Vol 2002 ◽  
pp. 66-66
Author(s):  
N. Ball ◽  
M.J. Haskell ◽  
J.L. Williams ◽  
J.M. Deag
Keyword(s):  
Quantitative Trait Loci ◽  
Quantitative Trait ◽  
Farm Animals ◽  
Behavioural Responses ◽  
Trait Loci ◽  
Breeding Programmes ◽  
Behavioural Phenotypes ◽  
Selection For ◽  
Temperament Traits ◽  
Behavioural Tests

Farm animals show individual variation in their behavioural responses to handling and management systems on farms. These behavioural responses are presumed to reflect underlying temperament traits such as fear or aggression. Information about the location of genes that influence temperament traits could be used in selective breeding programmes to improve animal welfare, as selection for desirable behavioural responses would increase the ability of animals to cope with stressors encountered on farms. The aims of this study were to obtain reliable temperament measurements in cattle using behavioural tests, and to use this data to localise the genes (quantitative trait loci) that are involved in such traits.Behavioural data obtained in temperament tests must be shown to reflect underlying traits by demonstrating intra-animal repeatability, inter-animal variability and validity. The objectives of this experiment were i) to carry out four behaviour tests on a group of heifers, and examine the repeatability, variability and validity of the results obtained; ii) to correlate the behavioural data with genotyping data from a large number of heifers to look for associations between behavioural phenotypes and genetic markers. Associations localise quantitative trait loci (QTLs), or regions of the genome, that are involved in these traits.

scholarly journals Mapping Quantitative Trait Loci for Resistance to Fall Armyworm (Lepidoptera: Noctuidae) Leaf-Feeding Damage in Maize Inbred Mp705

2020 ◽  
Vol 113 (2) ◽  
pp. 956-963 ◽  
Author(s):  
E D Womack ◽  
W P Williams ◽  
J S Smith ◽  
M L Warburton ◽  
D Bhattramakki
Keyword(s):  
Molecular Markers ◽  
Quantitative Trait Loci ◽  
Quantitative Trait ◽  
Fall Armyworm ◽  
Phenotypic Variance ◽  
Feeding Damage ◽  
Artificial Infestation ◽  
Lepidopteran Insects ◽  
Trait Loci ◽  
Important Pest

Abstract The fall armyworm, Spodoptera frugiperda (J. E. Smith), is an agronomically important pest that severely limits maize (Zea mays (Linnaeus) [Poales: Poaceae]) production. This migrant insect devastates maize plants in many countries threatening the livelihood of millions. Quantitative trait loci (QTL) were mapped to identify chromosomal regions that control resistance to fall armyworm leaf-feeding and to identify molecular markers linked to the target loci for use in marker-assisted selection (MAS). A bi-parental mapping population, comprising 243 F2:3 families from the cross Mp705 (resistant) × Mp719 (susceptible), was evaluated for fall armyworm leaf-feeding damage under artificial infestation over 3 yr. A linkage map comprised of 1,276 single-nucleotide polymorphism and simple sequence repeat molecular markers was constructed. Quantitative trait loci analyses identified two major QTL in bins 4.06 and 9.03 that when combined, explained 35.7% of the phenotypic variance over all environments. Mp705 was responsible for the leaf-feeding damage reducing alleles for both large effect QTL and most of the small effect QTL identified in this study. The QTL identified in bin 9.03 co-locates with a previously identified QTL that controls resistance to leaf-feeding damage in maize by fall armyworm and other lepidopteran insects. The QTL in bin 4.06 is a new source of resistance identified in this study. Beneficial alleles derived from Mp705 for the application of an integrated QTL-MAS approach could accelerate breeding efforts to minimize fall armyworm leaf-feeding in maize.

scholarly journals Chromosomal segments underlying quantitative trait loci for mohair production in Angora goats

2009 ◽  
Vol 45 ◽  
pp. 107-112 ◽  
Author(s):  
E.M. Cano ◽  
S. Debenedetti ◽  
M. Abad ◽  
D. Allain ◽  
H.R. Taddeo ◽  
...  
Keyword(s):  
Molecular Markers ◽  
Quantitative Trait Loci ◽  
Quantitative Trait ◽  
Fibre Diameter ◽  
Average Fibre Diameter ◽  
A Genome ◽  
Argentinean Patagonia ◽  
Trait Loci ◽  
Average Fibre ◽  
Angora Goats

SummaryThis study reports the results obtained in the search of chromosomal regions affecting fleece traits in a population of Angora goats in the Argentinean Patagonia. Six hundred thirty-four offspring from 14 parental half-sib families were used. Nine phenotypic fleece traits were recorded at 4 and 11 months of age. A genome examination using 85 informative molecular markers was conducted. A linkage analysis was performed using a regression interval analysis. Our study identified 10 genomic regions affecting the average fibre diameter, coefficient of variation of the average fibre diameter, percentage of fibres with diameters over 30 µm, greasy fleece weight, staple length, average curvature of fibres, percentage of continuous medullated fibres and percentage of kemp fibres located on five goat chromosomes (1, 2, 5, 13 and 19). These results show that the average size of the quantitative trait loci effect was 1.6 phenotypic standard deviations for different traits and families. The aims of quantitative trait loci detection is the potential use of these molecular markers to increase accuracy in predicting the genetic merit of breeding and its implementation in animal breeding schemes through marker-assisted selection.

scholarly journals Quantitative trait loci sequencing–derived molecular markers for selection of stem rot resistance in peanut

Crop Science ◽  
2020 ◽  
Vol 60 (4) ◽  
pp. 2008-2018
Author(s):  
Renjie Cui ◽  
Josh Clevenger ◽  
Ye Chu ◽  
Timothy Brenneman ◽  
Thomas G. Isleib ◽  
...  
Keyword(s):  
Molecular Markers ◽  
Quantitative Trait Loci ◽  
Quantitative Trait ◽  
Stem Rot ◽  
Trait Loci ◽  
Selection Of
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