Characterization of the genetic basis for yield and its component traits of rice revealed by doubled haploid population.

Main-effect QTL, epistatic effects and their interactions with environment are important genetic components of quantitative traits. In this study, we analyzed the QTLs, epistatic effects and QTL by environment interactions (QE) underlying nine traits of yield and yield-component, using a doubled-haploid (DH) population consisted of 190 lines from the cross between an indica parent Zhenshan 97 and a japonica parent WYJ 2, and tested in two-year replicated field trials. A genetic linkage map with 179 SSR (simple sequence repeat) marker loci was constructed. A mixed linear model approach was applied to detect QTLs, digenic interactions and QEs for the nine traits. In total, 57 QTLs of main effects, 41 digenic interactions, eight QEs and seven interactions of epistasis by environment were detected. Each of the main-effect QTLs individually explained 1.3 % to 25.8% of the phenotypic variations. And they collectively explained 11.5% to 66.8% of the phenotypic variations for these traits. Most of the traits (except seed setting) had the QTLs simultaneously detected in two years. Many of the traits shared same QTLs with each other, which is consistent with their significant phenotypic correlations. The pleiotropism or tight linkage of QTLs for different traits might be the important genetic base for trait correlations. The environmental influences on the stability of the trait performance were also discussed.