ESTIMATION OF THE AVERAGE EFFECTS OF SPECIFIC ALLELES DETECTED BY THEPSEUDO-TESTCROSS QTL MAPPING STRATEGY

In a full-sib progeny of a mating between heterozygous parents, the an alysis of marker-trait associations using dominant RAPD (random amplif ied polymorphic DNA) markers allows the detection of specific quantita tive trait loci (QTL) for each parent of the cross. Here we develop a method aimed at estimating the breeding Value of such QTL alleles in t he population, for the incorporation of marker-assisted selection in o perational forest tree-breeding programs. The proposed methodology exp ands on the pseudo-testcross QTL mapping strategy which is based on th e selection of single dose markers present in one parent and absent in the other. It specifically exploits the fact that one of the parents of the full-sib family is double null for the RAPD markers bracketing the QTL so that, by looking at its half-sib family, 'band present' all ele frequencies of the two markers can be obtained at the population l evel. The half-sib family of the other parent, which is doubly heteroz ygous, is then used to estimate the average effect (ie, the additive e ffect) of the two QTL alleles.