Marker-QTL linkage detection in self-families of outbred populations

In forest trees which are normally outcrossing, inbreeding by self-fertilis ation (selfing) generally has deleterious effects including reduced seed se t, poor seed germination, and slow seedling growth. Inbreeding depression ( ID) is mainly caused by deleterious alleles that will be almost never expre ssed under panmixis. Until the advent of molecular markers, there has been no way to track most of the individual genes causing ID. In this study, the theory for a single-marker ANOVA method was developed to find the linkage between a marker locus and a gene causing ID in growth traits in self-famil ies of outbred populations. The power of linkage detection, which was at th e lower limit because of single-marker method, was calculated for a wide ra nge of progeny sizes and genetic parameters at the quantitative trait locus (QTL). The magnitude of the gene effect was found to have an enormous effe ct on the power. The situations where the QTL detected in a self-family can be considered as those expressed in normal course of outbreeding are also discussed.