Temporal changes in allele frequencies in two European F2 flint maize populations under modified recurrent full-sib selection |
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Authors: | K C Falke C Flachenecker A E Melchinger H -P Piepho H P Maurer M Frisch |
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Institution: | (1) Institute of Plant Breeding, Seed Science, and Population Genetics, University of Hohenheim, 70593 Stuttgart, Germany;(2) Institute for Crop Production and Grassland Research, University of Hohenheim, 70593 Stuttgart, Germany |
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Abstract: | Selection and random genetic drift are the two main forces affecting the selection response of recurrent selection (RS) programs
by changes in allele frequencies. Therefore, detailed knowledge on allele frequency changes attributable to these forces is
of fundamental importance for assessing RS programs. The objectives of our study were to (1) estimate the number, position,
and genetic effect of quantitative trait loci (QTL) for selection index and its components in the base populations, (2) determine
changes in allele frequencies of QTL regions due to the effects of random genetic drift and selection, and (3) predict allele
frequency changes by using QTL results and compare these predictions with observed values. We performed QTL analyses, based
on restriction fragment length polymorphisms (RFLPs) and simple sequence repeats (SSRs), in 274 F2:3 lines of cross KW1265 × D146 (A × B) and 133 F3:4 lines of cross D145 × KW1292 (C × D) originating from two European flint maize populations. Four (A × B) and seven (C × D)
cycles of RS were analyzed with SSRs for significant allele frequency changes due to selection. Several QTL regions for selection
index were detected with simple and composite interval mapping. In some of them, flanking markers showed a significant allele
frequency change after the first and the final selection cycles. The correlation between observed and predicted allele frequencies
was significant only in A × B. We attribute these observations mainly to (1) the high dependence of the power of QTL detection
on the population size and (2) the occurrence of undetectable QTL in repulsion phase. Assessment of allele frequency changes
in RS programs can be used to detect marker alleles linked to QTL regions under selection pressure.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. |
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Keywords: | Allele frequency changes Random genetic drift Recurrent selection SSR Zea mays L |
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