ABSTRACT
A quantitative trait loci (QTL) is a statistical description of the phenotypic effects of a genetic locus or closely linked group of loci in a defined population and environment. Mathematical approach — using models that attempt to simultaneously estimate locations and effects of multiple QTLs rather than independently estimate individual locations of single QTLs, might improve the precision of QTL mapping. “Substitution mapping” — by screening large populations of progeny, one can determine the QTL genotype of individuals that contain recombination events near a QTL. In principle, early implementations of interval mapping acknowledged that additional QTLs might be resolved, or better resolution of existing QTLs obtained, by simultaneous mapping of multiple QTLs. A modified mathematical model, which removed the phenotypic effects of the Ma-1 locus from the “error” term, revealed two additional QTLs that met stringent statistical thresholds. Phenotypic evaluation of numerous progeny from each recombinant is necessary to accurately determine the QTL genotype of each recombinant.
