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Major QTL (major + qtl)
Selected AbstractsIdentification of genetic determinants of IGF-1 levels and longevity among mouse inbred strainsAGING CELL, Issue 5 2010Magalie S. Leduc Summary The IGF-1 signaling pathway plays an important role in regulating longevity. To identify the genetic loci and genes that regulate plasma IGF-1 levels, we intercrossed MRL/MpJ and SM/J, inbred mouse strains that differ in IGF-1 levels. Quantitative trait loci (QTL) analysis of IGF-1 levels of these F2 mice detected four QTL on chromosomes (Chrs) 9 (48 Mb), 10 (86 Mb), 15 (18 Mb), and 17 (85 Mb). Haplotype association mapping of IGF-1 levels in 28 domesticated inbred strains identified three suggestive loci in females on Chrs 2 (13 Mb), 10 (88 Mb), and 17 (28 Mb) and in four males on Chrs 1 (159 Mb), 3 (52 and 58 Mb), and 16 (74 Mb). Except for the QTL on Chr 9 and 16, all loci co-localized with IGF-1 QTL previously identified in other mouse crosses. The most significant locus was the QTL on Chr 10, which contains the Igf1 gene and which had a LOD score of 31.8. Haplotype analysis among 28 domesticated inbred strains revealed a major QTL on Chr 10 overlapping with the QTL identified in the F2 mice. This locus showed three major haplotypes; strains with haplotype 1 had significantly lower plasma IGF-1 and extended longevity (P < 0.05) than strains with haplotype 2 or 3. Bioinformatic analysis, combined with sequencing and expression studies, showed that Igf1 is the most likely QTL gene, but that other genes may also play a role in this strong QTL. [source] Histopathology and PR-protein markers provide insight into adult plant resistance to stripe rust of wheatMOLECULAR PLANT PATHOLOGY, Issue 2 2008JENNIFER MOLDENHAUER SUMMARY Stripe rust, caused by Puccinia striiformis f. sp. tritici, is a serious disease of wheat. The spring wheat cultivar Kariega expresses complete adult plant resistance to stripe rust, whereas Avocet S is susceptible. In former studies, quantitative trait loci (QTL) analysis of doubled haploid lines derived from a Kariega × Avocet S cross revealed two major QTL (QYr.sgi-7D and QYr.sgi-2B.1) and two minor QTL (QYr.sgi-1A and QYr.sgi-4A.1) responsible for the adult resistance of Kariega in the field. Avocet S contains none of these QTL. In the present study, stripe rust development was compared, by means of fluorescence and confocal laser scanning microscopy, in flag leaves of Kariega, Avocet S and six doubled haploid (DH) lines, containing all four, none or one QTL. Depending on the QTL present, the infection types of the DH lines ranged from resistant to fully susceptible. No differences in fungal growth were observed during the first 5 days post inoculation (dpi), whereas the mean length of the fungal colonies started to differ at 6 dpi. Interestingly, MP 51 carrying QYr.sgi-7D responded with lignification to the fungal growth without restricting it, whereas MP 35 containing QYr.sgi-2B.1 did not show lignified host tissue, but fungal growth was restricted. RT PCR experiments with sequences of pathogenesis-related (PR) proteins resulted in a slightly stronger induction of PR 1, 2 and 5, known markers for the hypersensitive reaction, and peroxidases in MP 51, whereas a second band for chitinases was detected in MP 35 only. [source] Quantitative trait loci analysis of mineral element concentrations in an Arabidopsis halleri × Arabidopsis lyrata petraea F2 progeny grown on cadmium-contaminated soilNEW PHYTOLOGIST, Issue 2 2010Glenda Willems Summary ,This study describes the quantitative trait locus (QTL) analysis of cadmium (Cd), zinc (Zn), iron (Fe), potassium (K), magnesium (Mg) and calcium (Ca) accumulation in the pseudometallophyte Arabidopsis halleri under conditions of Cd excess using an interspecific A. halleri × Arabidopsis lyrata F2 population. ,Our data provide evidence for the implication of one major QTL in Cd hyperaccumulation in A. halleri, and suggests that Cd tolerance and accumulation are not independent in A. halleri. Moreover, the major loci responsible for Zn hyperaccumulation in the absence of Cd appear to be the same when Cd is present at high concentrations. ,More than twofold higher Fe concentrations were measured in A. halleri shoots than in A. lyrata, suggesting a different regulation of Fe accumulation in the hyperaccumulator. ,With the exception of Ca, the accumulation of Cd was significantly correlated with the accumulation of all elements measured in the F2 progeny, suggesting pleiotropic gene action. However, QTL analysis identified pleiotropic QTLs only for Cd, Zn and Fe. Mg accumulation was negatively correlated with Cd accumulation, as well as with dry shoot biomass, suggesting that it might indicate cellular damage. [source] A major QTL for resistance of rice to the parasitic plant Striga hermonthica is not dependent on genetic backgroundPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 5 2009Philip J Swarbrick Abstract BACKGROUND: The use of Striga -resistant germplasm is likely to be a cost-effective control strategy for preventing loss of yield owing to Striga. Previously, the authors identified quantitative trait loci (QTL) for resistance in rice to Striga hermonthica (Del.) Benth. in backcross inbred lines (BILs) derived from a cross between two cultivars Nipponbare and Kasalath. It is essential to validate QTL in different environments and/or genetic backgrounds to develop molecular markers linked to resistance QTL for use in marker-assisted selection (MAS) programmes. This study aimed to establish whether a large-effect Kasalath-derived resistance QTL allele on chromosome 4 of rice also conferred resistance in a different mapping population derived from a cross between Koshihikari and Kasalath, and to identify any further Striga resistance QTL. RESULTS: Three Striga resistance QTL were detected in Koshihikari,Kasalath BILs, two of which were derived from the Kasalath allele and one from the Koshihkari allele. The largest QTL (Kasalath allele) explained 16% of the variation in the mapping population and was located on chromosome 4. Comparison between these data and those of the authors' previous analysis revealed that the confidence intervals of the chromosome-4 QTL in the Nipponbare,Kasalath cross and the Kasalath,Koshihikari cross overlapped between 6.5 Mbp and 8 Mbp on the physical rice genome assembly. CONCLUSION: This study has both verified and narrowed down the position of a Striga resistance QTL of major effect, and demonstrated that it may be a tractable target for MAS. Copyright © 2009 Society of Chemical Industry [source] Genetic analysis and QTL mapping of stalk digestibility and kernel composition in a high-oil maize mutant (Zea mays L.)PLANT BREEDING, Issue 3 2010H.-W. Wang With 1 figure and 5 tables Abstract A high-oil maize inbred line Ce03005 derived from ethylmethane-sulphonate mutagenesis was used to study the genetic basis of stalk digestibility and kernel chemical compositions, and evaluate the genetic relationship between traits. Quantitative trait loci (QTL) mapping employed 211 lines of F3 and F4 generations derived from Ce03005 × B73. Nuclear magnetic resonance and near-infrared reflectance spectrometry were used to analyse the following phenotypic traits: stalk digestibility and related traits including in vitro dry matter digestibility (IVDMD), in vitro cell wall digestibility (IVNDFD), neutral detergent fibre (NDF), acid detergent fibre (ADF), water soluble carbohydrate (WSC), and kernel composition including kernel oil content (KOC), kernel protein content (KPC) and kernel starch content (KSC). Correlation analysis indicated that IVDMD, IVNDFD and WSC were significantly (P = 0.01) positively correlated with KOC, while ADF and NDF were negatively correlated with KOC. Six QTL for IVDMD, five for IVNDFD, six for NDF, eight for ADF, three for WSC, eight for KOC, seven for KPC and 10 for KSC were detected in F3 and F4 generations. Five major QTL (R2 > 10) of qIVDMD6, qIVNDFD6, qNDF6, qADF6, qWSC6 andOlicm6 shared the same confidence interval on chromosome 6. The results suggested that KOC may be closely related or share the same QTL for stalk quality traits, and its change may have influences to the stalk components. [source] Detection of QTLs for bread-making quality in wheat using a recombinant inbred line populationPLANT BREEDING, Issue 3 2009Y. Li Abstract Whereas gluten fraction accounts for 30,60% of the variation in wheat bread-making quality, there remains substantial variation determined by non-gluten factors. The objective of this study was to detect new loci for wheat quality. The genetics of sodium dodecyl sulphate-sedimentation volume (Ssd), grain hardness (GH), grain protein content, wet gluten content (WGC) and water absorption (Abs) in a set of 198 recombinant inbred lines derived from two commercial varieties was studied by quantitative trait loci (QTL) analysis. A genetic map based on 255 marker loci, consisting of 250 simple sequence repeat markers and five glutenin loci, Glu-A1, Glu-B1, Glu-D1, Glu-B3 and Glu-D3, was constructed. A total of 73 QTLs were detected for all traits. A major QTL for GH was detected on chromosome 1B and its relative contribution to phenotypic variation was 27.7%. A major QTL for Abs on chromosome 5D explained more than 30% of the phenotypic variation. Variations in Ssd were explained by four kinds of genes. Some QTLs for correlated traits mapped to the same regions forming QTL clusters or indicated pleiotropic effects. [source] Development of STS markers and QTL validation for common bacterial blight resistance in common beanPLANT BREEDING, Issue 1 2008S. Liu Abstract Common bacterial blight (CBB) of common bean (Phaseolus vulgaris L.), is one of the major diseases that decrease yield and quality. A major quantitative trait locus (QTL) for CBB resistance from line XAN 159 was transferred into two bean lines, HR45 and HR67. Previous studies identified that two markers are linked to this QTL but the chromosome location was not consistent. To identify more tightly linked markers and to verify the chromosome location, 65 additional markers were mapped using 81 recombinant inbred lines (RILs) derived from a cross HR67 × OAC95-4. The QTL was mapped to a 13 cM region on chromosome 1 and defined by eight molecular markers that explained 25,52% of the phenotypic variation. Six tightly linked amplified fragment length polymorphism markers (0.6,9.7 cM from the QTL peak) were converted into seven sequence tagged site markers, three of which were mapped to this QTL. Five tightly linked markers were used to screen 907 F2 plants derived from a cross HR45 × ,OAC Rex' and four of them were linked to each other within 4.2 cM. These markers may be useful in marker-assisted selection and map-based cloning of this major QTL. [source] | ||||||||||