Doubled haploids for locating polygenes

1983 ◽  
Vol 25 (5) ◽  
pp. 425-429 ◽  
Author(s):  
T. M. Choo
Keyword(s):  
Doubled Haploid ◽  
Quantitative Trait ◽  
Doubled Haploids ◽  
Marker Gene ◽  
Marker Genes ◽  
Doubled Haploid Population ◽  
Crossing Over ◽  
Marker Loci ◽  
Haploid Population ◽  
Map Distance

A biometrical method, making use of one or two marker genes, was proposed for use in doubled-haploid populations to locate polygenes. A polygene, if located between two closely linked marker loci, can be detected in a doubled-haploid population derived from a cross of two diploid inbred parents. In addition, the presence of additive epistasis can be detected. If the map distance between the two marker loci is so close that the frequency of double crossing-over can be neglected, then the recombination values between the polygene and either marker gene can be estimated, and the additive effect of the polygene can be determined in the absence of pleiotropy. Further, the contribution of the polygene to the quantitative trait relative to all other polygenes can be measured from the experiment if double crossing-over and epistasis are absent. Note that the proposed method can be used as an adjunct to haploid breeding routines and other genetical experiments.

THE EFFICIENCY OF USING DOUBLED HAPLOIDS IN A RECURRENT SELECTION PROGRAM IN A DIPLOID, CROSS-FERTILIZED SPECIES

1978 ◽  
Vol 20 (4) ◽  
pp. 505-511 ◽  
Author(s):  
T. M. Choo ◽  
L. W. Kannenberg
Keyword(s):  
Doubled Haploid ◽  
Recurrent Selection ◽  
Doubled Haploids ◽  
Additive Genetic Variance ◽  
Significant Loss ◽  
Doubled Haploid Population ◽  
Mass Selection ◽  
Complete Dominance ◽  
Haploid Population ◽  
Selection Intensities

Mass selection in both doubled haploid and diploid populations was simulated for a 30-year period under additive and complete dominance models. The response to S1 selection was also included for the purpose of comparison. All selection programs were conducted at two selection intensities, 5% and 25%, under 0.2 heritability with a constant population size of 400. S1 lines were evaluated in 10-plant plots with four replications; use of a winter nursery was assumed. The character under selection was controlled by 20 major (A = 2) genes and 20 minor (A = 1) genes. The initial frequency of ten of the major genes and ten of the minor genes was 0.5; that of the remaining ten of each type was 0.1. The response to mass selection with doubled haploids was about 1.4 times faster than diploid mass selection and equal to S1 selection in terms of gain per year. If replicated trials were used to evaluate the doubled haploids, the rate of gain was faster than in S1 selection. The greater efficiency of using doubled haploids was due to doubling of the additive genetic variance and the elimination of dominance variance. However, significant loss of desirable genes occurred in the mass selected doubled haploid population under both the 5% and 25% selection intensities in the additive and complete dominance models.

Quantitative trait locus analysis of late maturity a-amylase in wheat using the doubled haploid population Cranbrook Halberd

2001 ◽  
Vol 52 (12) ◽  
pp. 1267 ◽  
Author(s):  
K. Mrva ◽  
D. J. Mares
Keyword(s):  
Quantitative Trait Locus ◽  
Doubled Haploid ◽  
Quantitative Trait ◽  
Triticum Aestivum L ◽  
Temperature Treatment ◽  
Doubled Haploid Population ◽  
Cool Temperature ◽  
Haploid Population ◽  
Late Maturity ◽  
Trait Locus

Mapping of the late maturity α-amylase (LMA) gene using quantitative trait locus (QTL) analysis represents an important step in identification of potential molecular markers that would greatly improve efficiency and accuracy of screening for LMA. QTL controlling the expression of LMA in wheat were detected in a doubled haploid (DH) cross/population derived from wheat (Triticum aestivum L. em. Thell) cultivars Cranbrook (LMA source) and Halberd (non-LMA). The DH population and parents were sown in replicated trials at Narrabri with sowing times differing by 2 weeks. Cool temperature treatment of detached tillers was used to induce expression of LMA in lines carrying the defect. The number of grains in ripe, treated tillers that contained high pI (malt, germination type) α-amylase isozymes was measured using an ELISA antibody kit highly specific for high pI isozymes. QTL analyses were conducted separately for each sowing, but results from both sowings were consistent and indicated that there was a highly significant (P < 0.001) QTL on the long arm of chromosome 7B (accounting for 31% of the variation in the first experiment), with Cranbrook contributing the higher value allele. A second QTL that accounted for 13% of the variation was found close to the centromere on chromosome 3B. Although it was less important than the QTL on 7B it was nevertheless still significant (P < 0.05).

Localisation of quantitative trait loci for quality attributes in a doubled haploid population of wheat (Triticum aestivum L.)

Genome ◽  
2009 ◽  
Vol 52 (8) ◽  
pp. 701-715 ◽  
Author(s):  
R. Raman ◽  
H. Allen ◽  
S. Diffey ◽  
H. Raman ◽  
P. Martin ◽  
...  
Keyword(s):  
Doubled Haploid ◽  
Quantitative Trait ◽  
Development Time ◽  
Doubled Haploid Population ◽  
Whole Genome ◽  
Quality Traits ◽  
Dough Strength ◽  
Haploid Population ◽  
Dough Extensibility ◽  
Dough Development Time

Selection of wheat germplasm for a range of quality traits has been a challenging exercise because of the cost of testing, the variation within testing data, and a poor understanding of the underlying genetics. The objective of this study was to identify quantitative trait loci (QTLs) underlying quality traits in wheat. A doubled haploid population comprising 190 lines from Chara/WW2449 was grown in two different environments and evaluated for various quality traits. A molecular map comprising 362 markers based upon simple sequence repeat, sequence tagged microsatellite, glutenin, and DArT loci was constructed and subsequently exploited to identify QTLs using a whole-genome approach. Fifteen QTLs that were consistent in the two different environments were identified for thousand kernel mass, grain protein content, milling yield, flour protein content, flour colour, flour water absorption, dough development time, dough strength (extensograph height and resistance at 5 cm), and dough extensibility (extensograph length) using the whole genome average interval mapping approach. The amount of genetic variation explained by individual QTLs ranged from 3% to 49%. A number of QTLs associated with dough strength, dough extensibility, dough development time, and flour water absorption were located close to the glutenin Glu-B1 locus on chromosome 1B. Identification of the chromosomal location and effect of the QTLs influencing wheat quality may hasten the development of superior wheats for target markets via marker-assisted selection.

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