Abstract
Mapping of quantitative trait loci (QTLs) in plants was performed using the data of marker genotypes and phenotypic values of a quantitative trait in a segregating generation such as F2 and BC1 derived from the crossing of two pure lines. A Iarge sample must be examined to map QTLs with small effects. However genotyping of many markers for a large number of individuals is costly. For mapping QTLs using a F2 population, useful information is included in the derived F3 Iines. Phenotypic measurements of F3 Iines can be obtained at a relatively low cost. Therefore, by utilizing tlhe phenotypic measurements of F3 in addition to F2 data, the detection of QTLs could be improved even when only a small number of F2 individuals are genotyped. In this paper a model for mapping QTLs is proposed, where the data of both F2 mdividuals and F3 Iines are jointly analyzed. The effectiveness of this method is evaluated theoretically and numerically and it is shown that the ability of detecting QTL can be remarkably enhanced, especially when the heritability of the trait is low.
