Minimum sample size and optimal positioning of flanking markers in marker-assisted backcrossing for transfer of a target gene

In recurrent backcrossing designed for introgression of a target allele fro m a donor into the genetic background of a recurrent parent (RP), molecular markers can accelerate recovery of the recurrent parent genome (RPG). The objectives of this study were to determine in marker-assisted backcrossing (MAB) (i) the optimum distances (d(1), d(2)) between the Banking markers an d the target locus and (ii) the minimum number of individuals (n) required far obtaining with a certain probability a given number of individuals that carry the donor allele at the target locus and have a minimum proportion o f donor genome on the carrier chromosome. Analytical solutions and tabulate d results are given for relevant parameters (d(1), d(2), n) required to obt ain, with a specified probability of success, at least one desired individu al, They depend on the length of the carrier chromosome, the chromosomal po sition of the target locus, its distance to the flanking marker loci, and t he number of individuals evaluated. Our approach can increase the efficienc y of MAB by reducing the number of individuals and marker data points requi red.