scholarly journals High resolution of quantitative traits into multiple loci via interval mapping.

Genetics ◽  
1994 ◽  
Vol 136 (4) ◽  
pp. 1447-1455 ◽  
Author(s):  
R C Jansen ◽  
P Stam
Keyword(s):  
Recombinant Inbred Lines ◽  
Interval Mapping ◽  
Maximum Likelihood Estimates ◽  
Model Parameters ◽  
Multiple Loci ◽  
F1 Progeny ◽  
F2 Generation ◽  
F2 Progeny ◽  
General Method ◽  
Qtl Effects

Abstract A very general method is described for multiple linear regression of a quantitative phenotype on genotype [putative quantitative trait loci (QTLs) and markers] in segregating generations obtained from line crosses. The method exploits two features, (a) the use of additional parental and F1 data, which fixes the joint QTL effects and the environmental error, and (b) the use of markers as cofactors, which reduces the genetic background noise. As a result, a significant increase of QTL detection power is achieved in comparison with conventional QTL mapping. The core of the method is the completion of any missing genotypic (QTL and marker) observations, which is embedded in a general and simple expectation maximization (EM) algorithm to obtain maximum likelihood estimates of the model parameters. The method is described in detail for the analysis of an F2 generation. Because of the generality of the approach, it is easily applicable to other generations, such as backcross progenies and recombinant inbred lines. An example is presented in which multiple QTLs for plant height in tomato are mapped in an F2 progeny, using additional data from the parents and their F1 progeny.

scholarly journals Integration and Modularity of Quantitative Trait Locus Effects on Geometric Shape in the Mouse Mandible

Genetics ◽  
2004 ◽  
Vol 166 (4) ◽  
pp. 1909-1921
Author(s):  
Christian Peter Klingenberg ◽  
Larry J Leamy ◽  
James M Cheverud
Keyword(s):  
Quantitative Trait ◽  
Parametric Bootstrap ◽  
Interval Mapping ◽  
Procrustes Analysis ◽  
Bootstrap Test ◽  
Mandible Shape ◽  
Trait Locus ◽  
F2 Generation ◽  
Analysis Interval ◽  
Qtl Effects

Abstract The mouse mandible has long served as a model system for complex morphological structures. Here we use new methodology based on geometric morphometrics to test the hypothesis that the mandible consists of two main modules, the alveolar region and the ascending ramus, and that this modularity is reflected in the effects of quantitative trait loci (QTL). The shape of each mandible was analyzed by the positions of 16 morphological landmarks and these data were analyzed using Procrustes analysis. Interval mapping in the F2 generation from intercrosses of the LG/J and SM/J strains revealed 33 QTL affecting mandible shape. The QTL effects corresponded to a variety of shape changes, but ordination or a parametric bootstrap test of clustering did not reveal any distinct groups of QTL that would affect primarily one module or the other. The correlations of landmark positions between the two modules tended to be lower than the correlations between arbitrary subsets of landmarks, indicating that the modules were relatively independent of each other and confirming the hypothesized location of the boundary between them. While these results are in agreement with the hypothesis of modularity, they also underscore that modularity is a question of the relative degrees to which QTL contribute to different traits, rather than a question of discrete sets of QTL contributing to discrete sets of traits.

scholarly journals Analysis of Quantitative Trait Locus Effects on the Size and Shape of Mandibular Molars in Mice

Genetics ◽  
2002 ◽  
Vol 160 (4) ◽  
pp. 1573-1586 ◽  
Author(s):  
Michael Scott Workman ◽  
Larry J Leamy ◽  
Eric J Routman ◽  
James M Cheverud
Keyword(s):  
Interval Mapping ◽  
Size And Shape ◽  
Mandibular Molar ◽  
Shape Effects ◽  
Mandible Shape ◽  
Components Analysis ◽  
Trait Locus ◽  
F2 Progeny ◽  
Shape Data ◽  
Qtl Effects

AbstractWhile >50 genes have been found to influence the development of teeth in mice, we still know very little about the genetic basis for the adaptive characteristics of teeth, such as size and shape. We applied interval mapping procedures to Procrustes size and shape data obtained from 10 morphological landmarks on the mandibular molar row of the F2 progeny from a cross between the LG/J and SM/J strains of mice. This revealed many more QTL for molar shape (18) than for molar centroid size (3), although levels of dominance effects were comparable among QTL for size and shape. Comparisons of patterns of Procrustes additive and dominance shape effects and ordination of QTL effects by principal components analysis suggested that the effects of the shape QTL were dispersed among the three molars and thus that none of these molars represents a genetically distinct developmental structure. The results of an analysis of co-occurrence of QTL for molar shape, mandible shape, and cranial dimensions in these mice suggested that many of the QTL for molar shape may be the same as those affecting these other sets of characters, although in some cases this could be due to effects of closely linked genes.

Marker-Assisted Introgression of Favorable Alleles at Quantitative Trait Loci Between Maize Elite Lines

Genetics ◽  
2002 ◽  
Vol 162 (4) ◽  
pp. 1945-1959
Author(s):  
Agnès Bouchez ◽  
Frédéric Hospital ◽  
Mathilde Causse ◽  
André Gallais ◽  
Alain Charcosset
Keyword(s):  
Quantitative Trait Loci ◽  
Quantitative Trait ◽  
Recombinant Inbred Lines ◽  
Interval Mapping ◽  
Linkage Drag ◽  
Favorable Alleles ◽  
Genotype By Environment ◽  
Trait Loci ◽  
Qtl Effects ◽  
Good Agreement

Abstract This article reports the marker-assisted introgression of favorable alleles at three quantitative trait loci (QTL) for earliness and grain yield among maize elite lines. The QTL were originally detected in 1992 by means of ANOVA in a population of 96 recombinant inbred lines (RILs). Introgression started from a selected RIL, which was crossed three times to one of the original parents and then self-fertilized, leading to BC3S1 progenies. Markers were used to assist both foreground and background selection at each generation. At the end of the program, the effect of introgression was assessed phenotypically in agronomic trials, and QTL detection was performed by composite interval mapping among BC3S1 progenies. The marker-assisted introgression proved successful at the genotypic level, as analyzed by precision graphical genotypes, although no emphasis was put on the reduction of linkage drag around QTL. Also, QTL positions were generally sustained in the introgression background. For earliness, the magnitude and sign of the QTL effects were in good agreement with those expected from initial RIL analyses. Conversely, for yield, important discrepancies were observed in the magnitude and sign of the QTL effects observed after introgression, when compared to those expected from initial RIL analyses. These discrepancies are probably due to important genotype-by-environment interactions.

Quantitative Trait Loci for the Monoamine-Related Traits Heart Rate and Headless Behavior inDrosophila melanogaster

Genetics ◽  
2001 ◽  
Vol 157 (1) ◽  
pp. 283-294 ◽  
Author(s):  
Kristie Ashton ◽  
Ana Patricia Wagoner ◽  
Roland Carrillo ◽  
Greg Gibson
Keyword(s):  
Heart Rate ◽  
Genetic Variation ◽  
Recombinant Inbred Lines ◽  
Model Organism ◽  
Interval Mapping ◽  
Activity Levels ◽  
Environmental Variance ◽  
Genome Wide ◽  
A Genome ◽  
Monoamine Receptors

AbstractDrosophila melanogaster appears to be well suited as a model organism for quantitative pharmacogenetic analysis. A genome-wide deficiency screen for haploinsufficient effects on prepupal heart rate identified nine regions of the genome that significantly reduce (five deficiencies) or increase (four deficiencies) heart rate across a range of genetic backgrounds. Candidate genes include several neurotransmitter receptor loci, particularly monoamine receptors, consistent with results of prior pharmacological manipulations of heart rate, as well as genes associated with paralytic phenotypes. Significant genetic variation is also shown to exist for a suite of four autonomic behaviors that are exhibited spontaneously upon decapitation, namely, grooming, grasping, righting, and quivering. Overall activity levels are increased by application of particular concentrations of the drugs octopamine and nicotine, but due to high environmental variance both within and among replicate vials, the significance of genetic variation among wild-type lines for response to the drugs is difficult to establish. An interval mapping design was also used to map two or three QTL for each behavioral trait in a set of recombinant inbred lines derived from the laboratory stocks Oregon-R and 2b.

scholarly journals A Family of Loss Distributions with an Application to the Vehicle Insurance Loss Data

2019 ◽  
pp. 731-744 ◽  
Author(s):  
Zubair Ahmad Ahmad ◽  
Eisa Mahmoudi Mahmoudi ◽  
G. G. Hamedani
Keyword(s):  
Maximum Likelihood ◽  
Financial Risk ◽  
Maximum Likelihood Estimates ◽  
Model Parameters ◽  
Data Set ◽  
Loss Model ◽  
New Class ◽  
Proposed Model ◽  
Loss Distributions ◽  
Loss Data

Actuaries are often in search of nding an adequate loss model in the scenario of actuarial and financial risk management problems. In this work, we propose a new approach to obtain a new class of loss distributions. A special sub-model of the proposed family, called the Weibull-loss model isconsidered in detail. Some mathematical properties are derived and maximum likelihood estimates of the model parameters are obtained. Certain characterizations of the proposed family are also provided. A simulation study is done to evaluate the performance of the maximum likelihood estimators. Finally, an application of the proposed model to the vehicle insurance loss data set is presented.

scholarly journals Seleksi Berbasis Marka Molekuler pada Padi Generasi F2 Guna Merakit Galur Padi Harapan Tahan Wereng Coklat

Agrikultura ◽  
2016 ◽  
Vol 27 (1) ◽  
Author(s):  
Nono Carsono ◽  
Gigih Ibnu Prayoga ◽  
Neni Rostini ◽  
Danar Dono
Keyword(s):  
Ssr Markers ◽  
Simple Sequence Repeat ◽  
Yield Loss ◽  
Insect Pest ◽  
Brown Planthopper ◽  
F2 Population ◽  
Significant Yield ◽  
F2 Generation ◽  
F2 Progeny ◽  
Simple Sequence

ABSTRACTMolecular Marker-based Selection on F2 Progeny for Development of Promising Rice Lines Resistant to Brown PlanthopperBrown planthopper (BPH) is the major insect pest of rice and accounts for significant yield loss. This experiment was aimed to develop BC1F1 and F3 brown planthopper resistant rice lines. Selection on the basis of SSR markers can be done by using two polymorphic SSR markers, i.e., RM586 dan RM8213, which screened from eight SSR markers for BPH resistant. Sixty-three F2 genotypes from IP-1 (derived from IR-64 x PTB-33) population and twenty F2 genotypes from PP-11 (derived from Pandan Wangi x PTB-33) population were selected and will be used for further research by selfed and backcrossed to recipient parents. Chi-squares test for segregation of DNA bands in F2 generation showed that RM8213 fitted with 1:2:1 Mendelian ratio for controlling photosynthetic rates and trichomes length in IP-1 population. This information could be used in programs to develop a durable brown planthopper resistant rice cultivar.Keywords: BPH, F2 population, Moleculer marker, SSRABSTRAKWereng coklat merupakan salah satu hama utama pada tanaman padi yang mampu menurunkan produksi padi secara nyata. Penelitian ini bertujuan untuk memperoleh galur-galur padi F2 yang memiliki marka-marka yang berasosisasi dengan ketahanannya terhadap wereng coklat. Seleksi pada galur padi F2 hasil persilangan telah dilakukan melalui teknik marka molekuler Simple Sequence Repeat (SSR) menggunakan dua marka SSR yang menunjukkan polimorphisme yaitu RM586 dan RM8213 dari delapan marka yang diskrining. Sebanyak 63 genotip dari populasi IP-1 (hasil persilangan IR-64 x PTB-33) dan 20 genotip dari populasi PP-11 (hasil persilangan Pandan Wangi x PTB-33) untuk disilangkan sendiri maupun disilang balik dengan tetua recipient. Selain itu, hasil analisis Chi-Kuadrat untuk segregasi pita DNA menunjukkan bahwa primer RM8213 memiliki rasio 1:2:1 (dominasi tidak sempurna) dalam mengontrol karakter laju fotosintesis dan panjang trikoma terhadap wereng coklat pada populasi IP-1. Informasi yang diperoleh dari penelitian ini nantinya dapat digunakan untuk program perakitan kultivar padi tahan wereng coklat yang durable.Kata Kunci: Marka molekuler, Populasi F2, SSR, Wereng coklat

scholarly journals The Weibull Birnbaum-Saunders Distribution And Its Applications

2020 ◽  
Vol 9 (1) ◽  
pp. 61-81
Author(s):  
Lazhar BENKHELIFA
Keyword(s):  
Maximum Likelihood ◽  
Estimation Method ◽  
Likelihood Estimation ◽  
Real Data ◽  
Reliability Estimation ◽  
Maximum Likelihood Estimates ◽  
Model Parameters ◽  
Data Sets ◽  
Proposed Model ◽  
Modeling Data

A new lifetime model, with four positive parameters, called the Weibull Birnbaum-Saunders distribution is proposed. The proposed model extends the Birnbaum-Saunders distribution and provides great flexibility in modeling data in practice. Some mathematical properties of the new distribution are obtained including expansions for the cumulative and density functions, moments, generating function, mean deviations, order statistics and reliability. Estimation of the model parameters is carried out by the maximum likelihood estimation method. A simulation study is presented to show the performance of the maximum likelihood estimates of the model parameters. The flexibility of the new model is examined by applying it to two real data sets.

scholarly journals Identification of quantitative trait loci for leaf traits in rice

Genetika ◽  
2016 ◽  
Vol 48 (2) ◽  
pp. 643-652 ◽  
Author(s):  
Baoyan Jia ◽  
Xinhua Zhao ◽  
Yang Qin ◽  
Muhammad Irfan ◽  
Tae-Heon Kim ◽  
...  
Keyword(s):  
Recombinant Inbred Lines ◽  
Leaf Traits ◽  
Rice Cultivar ◽  
Interval Mapping ◽  
Mapping Method ◽  
Japonica Rice ◽  
Phenotypic Variance ◽  
Simple Sequence ◽  
Variance Explained ◽  
Map Distance

A recombinant inbred lines (RILs) population of 90 lines were developed from a subspecies cross between an indica type cultivar, ?Cheongcheong?, and a japonica rice cultivar, ?Nagdong? was evaluated for leaf traits in 2009. A genetic linkage map consisting of 154 simple sequence repeat (SSR) markers was constructed, covering 1973.6 cM of 12 chromosomes with an average map distance of 13.9 cM between markers. By composite interval mapping method a total of 19 QTLs were identified for the leaf traits on 5 chromosomes (Chr.1, Chr.3, Chr.6, Chr.8 and Chr.11). The percentage of phenotypic variance explained by each QTL varied from 8.1% to 29.4%. Five pleiotropic effects loci were identified on chromosomes 1,6.

Mapping QTLs for 100-seed weight in an interspecific soybean cross of Williams 82 (Glycine max) and PI 366121 (Glycine soja)

2017 ◽  
Vol 68 (2) ◽  
pp. 148 ◽  
Author(s):  
Krishnanand P. Kulkarni ◽  
Sovetgul Asekova ◽  
Dong-Ho Lee ◽  
Kristin Bilyeu ◽  
Jong Tae Song ◽  
...  
Keyword(s):  
Seed Weight ◽  
Glycine Soja ◽  
Recombinant Inbred Lines ◽  
Molecular Genetic ◽  
Interval Mapping ◽  
Major Influence ◽  
Environment Interaction ◽  
Molecular Genetic Basis ◽  
The Individual ◽  
100 Seed Weight

Seed weight can be an important component for soybean quality and yield. The objective of the present study was to identify quantitative trait loci (QTLs) for 100-seed weight by using 169 recombinant inbred lines (RILs) derived from the cross Williams 82 × PI 366121. The parental lines and RILs were grown for four consecutive years (2012–15) in the field. The seeds were harvested after maturity, dried and used to measure 100-seed weight. Analysis of variance indicated significant differences among the RILs for 100-seed weight. The environment had significant effect on seed-weight expression as indicated by the genotype × environment interaction. QTL analysis employing inclusive composite interval mapping of additive QTLs implemented in QTL IciMapping (Version 4.1) identified nine QTLs (LOD >3) on chromosomes 1, 2, 6, 8, 13, 14, 17 and 20. The individual QTLs explained phenotypic variation in the range 6.1–12.4%. The QTLs were detected in one or two environments, indicating major influence of the growing environment on seed-weight expression. Four QTLs identified in this study, qSW-02_1, qSW-06_1, qSW-13_1 and qSW-14_1, were found to be new QTLs. The findings of the study may be helpful to reveal the molecular genetic basis of the seed-weight trait in soybean.

scholarly journals Characterizing and Mapping Resistance in Synthetic-Derived Wheat to Rhizoctonia Root Rot in a Green Bridge Environment

2016 ◽  
Vol 106 (10) ◽  
pp. 1170-1176 ◽  
Author(s):  
A. K. Mahoney ◽  
E. M. Babiker ◽  
T. C. Paulitz ◽  
D. See ◽  
P. A. Okubara ◽  
...  
Keyword(s):  
Pacific Northwest ◽  
Root Rot ◽  
Recombinant Inbred Lines ◽  
Genetic Resistance ◽  
Genotyping By Sequencing ◽  
Interval Mapping ◽  
Environmentally Sustainable ◽  
Soilborne Disease ◽  
Rhizoctonia Root Rot ◽  
Green Bridge

Root rot caused by Rhizoctonia spp. is an economically important soilborne disease of spring-planted wheat in growing regions of the Pacific Northwest (PNW). The main method of controlling the disease currently is through tillage, which deters farmers from adopting the benefits of minimal tillage. Genetic resistance to this disease would provide an economic and environmentally sustainable resource for farmers. In this study, a collection of synthetic-derived genotypes was screened in high-inoculum and low-inoculum field environments. Six genotypes were found to have varying levels of resistance and tolerance to Rhizoctonia root rot. One of the lines, SPBC-3104 (‘Vorobey’), exhibited good tolerance in the field and was crossed to susceptible PNW-adapted ‘Louise’ to examine the inheritance of the trait. A population of 190 BC1-derived recombinant inbred lines was assessed in two field green bridge environments and in soils artificially infested with Rhizoctonia solani AG8. Genotyping by sequencing and composite interval mapping identified three quantitative trait loci (QTL) controlling tolerance. Beneficial alleles of all three QTL were contributed by the synthetic-derived genotype SPCB-3104.

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