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Detected QTL (detected + qtl)
Selected AbstractsNatural selection for salt tolerance quantitative trait loci (QTLs) in wild sunflower hybrids: Implications for the origin of Helianthus paradoxus, a diploid hybrid speciesMOLECULAR ECOLOGY, Issue 5 2003C. Lexer Abstract For a new diploid or homoploid hybrid species to become established, it must diverge ecologically from parental genotypes. Otherwise the hybrid neospecies will be overcome by gene flow or competition. We initiated a series of experiments designed to understand how the homoploid hybrid species, Helianthus paradoxus, was able to colonize salt marsh habitats, when both of its parental species (H. annuus×H. petiolaris) are salt sensitive. Here, we report on the results of a quantitative trait locus (QTL) analysis of mineral ion uptake traits and survivorship in 172 BC2 hybrids between H. annuus and H. petiolaris that were planted in H. paradoxus salt marsh habitat in New Mexico. A total of 14 QTLs were detected for mineral ion uptake traits and three for survivorship. Several mineral ion QTLs mapped to the same position as the survivorship QTLs, confirming previous studies, which indicated that salt tolerance in Helianthus is achieved through increased Ca uptake, coupled with greater exclusion of Na and related mineral ions. Of greater general significance was the observation that QTLs with effects in opposing directions were found for survivorship and for all mineral ion uptake traits with more than one detected QTL. This genetic architecture provides an ideal substrate for rapid ecological divergence in hybrid neospecies and offers a simple explanation for the colonization of salt marsh habitats by H. paradoxus. Finally, selection coefficients of +0.126, ,0.084 and ,0.094 for the three survivorship QTLs, respectively, are sufficiently large to account for establishment of new, homoploid hybrid species. [source] Quantitative resistance to Plum pox virus in Prunus davidiana P1908 linked to components of the eukaryotic translation initiation complexPLANT PATHOLOGY, Issue 3 2009G. Marandel A complex, polygenic resistance to Plum pox virus (PPV) was previously described in a wild peach-related species, Prunus davidiana clone P1908. In the current study, an analysis of quantitative trait loci (QTL) was performed on an F2 population comprising 99 individuals obtained by selfing the F1 individual #40 of an interspecific cross between susceptible nectarine cv. Summergrand and the resistant P. davidiana clone P1908. Six QTL were identified using both parametric and non-parametric methods of detection, individually explaining 5,28% of the phenotypic variance. The total phenotypic variation explained ranged from 29 to 58%. Alignment of the genetic map of the F2 cross with the P. davidiana parent map showed consistency of QTL over generations, with three of the six QTL co-localizing at the 1-LOD interval and another one at the 2-LOD interval. Two of the QTL were mapped onto linkage group one, where resistance to PPV was previously mapped in apricot. Development and mapping of new microsatellite markers linked to candidate genes revealed a striking co-localization of three of the detected QTL with gene copies coding for eukaryotic translation initiation factors eIF4E and eIF(iso)4G. As co-localization of one QTL with candidate gene eIF(iso)4E was previously reported in the F1 population, the results reported here strongly reinforce the idea that components of the eukaryotic translation initiation complex are correlated with resistance to PPV in P. davidiana P1908. [source] Whole genome scan to detect quantitative trait loci for bovine milk protein compositionANIMAL GENETICS, Issue 4 2009G. C. B. Schopen Summary The objective of this study was to perform a whole genome scan to detect quantitative trait loci (QTL) for milk protein composition in 849 Holstein,Friesian cows originating from seven sires. One morning milk sample was analysed for the major milk proteins using capillary zone electrophoresis. A genetic map was constructed with 1341 single nucleotide polymorphisms, covering 2829 centimorgans (cM) and 95% of the cattle genome. The chromosomal regions most significantly related to milk protein composition (Pgenome < 0.05) were found on Bos taurus autosomes (BTA) 6, 11 and 14. The QTL on BTA6 was found at about 80 cM, and affected ,S1 -casein, ,S2 -casein, ,-casein and ,-casein. The QTL on BTA11 was found at 124 cM, and affected ,-lactoglobulin, and the QTL on BTA14 was found at 0 cM, and affected protein percentage. The proportion of phenotypic variance explained by the QTL was 3.6% for ,-casein and 7.9% for ,-casein on BTA6, 28.3% for ,-lactoglobulin on BTA11, and 8.6% for protein percentage on BTA14. The QTL affecting ,S2 -casein on BTA6 and 17 showed a significant interaction. We investigated the extent to which the detected QTL affecting milk protein composition could be explained by known polymorphisms in ,-casein, , -casein, ,-lactoglobulin and DGAT1 genes. Correction for these polymorphisms decreased the proportion of phenotypic variance explained by the QTL previously found on BTA6, 11 and 14. Thus, several significant QTL affecting milk protein composition were found, of which some QTL could partially be explained by polymorphisms in milk protein genes. [source] Identification of quantitative trait loci for growth and carcass composition in cattle,ANIMAL GENETICS, Issue 1 2004E. Casas Summary A genomic screening to detect quantitative trait loci (QTL) affecting growth, carcass composition and meat quality traits was pursued. Two hundred nineteen microsatellite markers were genotyped on 176 of 620 (28%) progeny from a Brahman × Angus sire mated to mostly MARC III dams. Selective genotyping, based on retail product yield (%) and fat yield (%), was used to select individuals to be genotyped. Traits included in the study were birth weight (kg), hot carcass weight (kg), retail product yield, fat yield, marbling score (400 = slight00 and 500 = small00), USDA yield grade, and estimated kidney, heart and pelvic fat (%). The QTL were classified as significant when the expected number of false positives (ENFP) was less than 0.05 (F -statistic greater than 17.3), and suggestive when the ENFP was <1 (F -statistic between 10.2 and 17.3). A significant QTL (F = 19; ENFP = 0.02) was detected for marbling score at centimorgan (cM) 54 on chromosome 2. Suggestive QTL were detected for fat yield at 50 cM, for retail product yield at 53 cM, and for USDA yield grade at 63 cM on chromosome 1, for marbling score at 56 cM, for retail product yield at 70 cM, and for estimated kidney, heart and pelvic fat at 79 cM on chromosome 3, for marbling score at 44 cM, for hot carcass weight at 49 cM, and for estimated kidney, heart and pelvic fat at 62 cM on chromosome 16, and for fat yield at 35 cM on chromosome 17. Two suggestive QTL for birth weight were identified, one at 12 cM on chromosome 20 and the other at 56 cM on chromosome 21. An additional suggestive QTL was detected for retail product yield, for fat yield, and for USDA yield grade at 26 cM on chromosome 26. Results presented here represent the initial search for quantitative trait loci in this family. Validation of detected QTL in other populations will be necessary. [source] | ||||||||||