scholarly journals A Generalization of the Mixture Model in the Mapping of Quantitative Trait Loci for Progeny From a Biparental Cross of Inbred Lines

Genetics ◽  
1996 ◽  
Vol 143 (1) ◽  
pp. 571-577
Author(s):  
R D Fisch ◽  
M Ragot ◽  
G Gay
Keyword(s):  
Molecular Markers ◽  
Quantitative Trait Loci ◽  
Molecular Marker ◽  
Mixture Model ◽  
Quantitative Trait ◽  
Doubled Haploids ◽  
Inbred Lines ◽  
Quantitative Inheritance ◽  
Trait Loci ◽  
Biometrical Models

Abstract The recent advent of molecular markers has created a great potential for the understanding of quantitative inheritance. In parallel to rapid developments and improvements in molecular marker technologies, biometrical models have been constructed, refined and generalized for the mapping of quantitative trait loci (QTL). However, current models present restricitions in terms of breeding designs to which they apply. In this paper, we develop an approach for the generalization of the mixture model for progeny from a single bi-parental cross of inbred lines. Detailed derivations are given for genetic designs involving populations developed by selfing, i.e., where marker genotypes are obtained from Fx (x ≤ 2) individuals and where phenotypes are measured on Fy (y ≥ x) individuals or families. Extensions to designs involving doubled-haploids, backcrossderived individuals and random matings are outlined. The derivations presented here can easily be combined with current QTL mapping approaches.

scholarly journals A general mixture model approach for mapping quantitative trait loci from diverse cross designs involving multiple inbred lines

2000 ◽  
Vol 75 (3) ◽  
pp. 345-355 ◽  
Author(s):  
YUEFU LIU ◽  
ZHAO-BANG ZENG
Keyword(s):  
Quantitative Trait Loci ◽  
Statistical Method ◽  
Mixture Model ◽  
Quantitative Trait ◽  
Genetic Model ◽  
General Procedure ◽  
Inbred Lines ◽  
Design Matrix ◽  
Trait Loci ◽  
Parental Lines

Most current statistical methods developed for mapping quantitative trait loci (QTL) based on inbred line designs apply to crosses from two inbred lines. Analysis of QTL in these crosses is restricted by the parental genetic differences between lines. Crosses from multiple inbred lines or multiple families are common in plant and animal breeding programmes, and can be used to increase the efficiency of a QTL mapping study. A general statistical method using mixture model procedures and the EM algorithm is developed for mapping QTL from various cross designs of multiple inbred lines. The general procedure features three cross design matrices, W, that define the contribution of parental lines to a particular cross and a genetic design matrix, D, that specifies the genetic model used in multiple line crosses. By appropriately specifying W matrices, the statistical method can be applied to various cross designs, such as diallel, factorial, cyclic, parallel or arbitrary-pattern cross designs with two or multiple parental lines. Also, with appropriate specification for the D matrix, the method can be used to analyse different kinds of cross populations, such as F2 backcross, four-way cross and mixed crosses (e.g. combining backcross and F2). Simulation studies were conducted to explore the properties of the method, and confirmed its applicability to diverse experimental designs.

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 Quantitative trait loci for lifespan of mated Drosophila melanogaster affect both sexes

2002 ◽  
Vol 80 (3) ◽  
pp. 225-230 ◽  
Author(s):  
SARAH G. REIWITCH ◽  
SERGEY V. NUZHDIN
Keyword(s):  
Quantitative Trait Loci ◽  
Quantitative Trait ◽  
Recombinant Inbred Lines ◽  
Inbred Lines ◽  
Specific Effects ◽  
Genome Wide ◽  
Evolution Of Life ◽  
Trait Loci ◽  
Males And Females ◽  
Qtls Mapping

The properties of alleles at quantitative trait loci (QTLs) contributing to variation in lifespan should be described to determine the mechanisms of evolution of life length and to predict its future changes. Previously, we and others conducted genome-wide screens for QTLs that segregate among one panel of recombinant inbred lines (RILs) using a dense molecular marker map. In non-stressful conditions, QTLs effecting the lifespans of virgin females and males were frequently sex specific. In an unrelated panel of RILs, the effects of QTLs in flies maintained in cages with mixed sexes were similar in both sexes. Here, we re-measured the lifespans of the former panel of RILs in cages with mixed sex cohorts. Lifespan declined owing to mating. The amount of decline correlated between sexes within lines. QTLs mapping to the intervals 15A–19C, 50B–57C, 63A–65A, and 96F–99B had similar effects on the lifespans of both males and females. These QTLs have previously been detected in virgin flies surveys and had sex- and/or environment-specific effects.

Sign in / Sign up

Export Citation Format

Share Document