Genetics. Published Articles Ahead of Print: June 18, 2008, Copyright © 2008
doi:10.1534/genetics.108.089680


A more recent version of this article appeared on July 1, 2008.

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Genetic analysis of heterosis for yield and yield components in rapeseed (Brassica napus L.) by QTL mapping

Mladen Radoev 1, Heiko C. Becker 1 and Wolfgang Ecke 1*

1 Georg-August-University Göttingen

* To whom correspondence should be addressed. E-mail: wecke{at}gwdg.de.

Submitted on March 28, 2008
Revised on April 21, 2008
Accepted on 21 April 2008


Abstract

The main objective in this research was the genetic analysis of heterosis in rapeseed at QTL level. A linkage map comprising 235 SSR and 144 AFLP markers covering 2045 cM was constructed in a doubled haploid population from a cross between the cultivar "Express: and the resynthesized line "R53." In field experiments at four locations in Germany 250 DH lines and their corresponding testcrosses with "Express" were evaluated for grain yield and three yield components. The heterosis ranged from 30% for grain yield to 0.7% for kernel weight. QTL were mapped using three different datasets allowing the estimation of additive and dominance effects as well as digenic epistatic interactions. In total, 33 QTL were detected of which 10 showed significant dominance effects. For grain yield, mainly complete dominance or overdominance was observed, whereas the other traits showed mainly partial dominance. A large number of epistatic interactions was detected. It was concluded that epistasis together with all levels of dominance from partial to overdominance is responsible for the expression of heterosis in rapeseed.

Key Words: Dominance ratio, Heterosis, Quantitative trait loci, Rapeseed, Simple Sequence Repeats