QTL ANALYSIS - A SIMPLE MARKER-REGRESSION APPROACH

A method to locate quantitative trait loci (QTL) on a chromosome and t o estimate their additive and dominance effects is described. It appli es to generations derived from an F-1 by selfing or backcrossing and t o doubled haploid lines, given that marker genotype information (RFLP, RAPD, etc.) and quantitative trait data are available. The method inv olves regressing the additive difference between marker genotype means at a locus against a function of the recombination frequency between that locus and a putative QTL. A QTL is located, as by other regressio n methods, at that point where the residual mean square is minimised. The estimates of location and gene effects are consistent and as relia ble as conventional flanking-marker methods. Further applications incl ude the ability to test for the presence of two, or more, linked QTL a nd to compare different crosses for the presence of common QTL. Furthe rmore, the technique is straightforward and may be programmed using st andard pc-based statistical software.