Probability of a recombinant inbred diploid plant for two linked genes

Abstract

For some discreet traits, breeders may need to break genetic linkage between a desirable trait and an undesirable trait. Breeders need to be able to determine the minimum number of plants to grow to have a specified probability of identifying at least one plant that is recombinant between two linked loci. Since 1931, recurrence equations have been available to determine the genotypic frequencies of each genotype when two loci are linked as the level of inbreeding changes. However, these genotypic frequencies have not been published in a tabular form that would be helpful to the applied plant breeder. The objectives are to: (1) provide genotypic proportions as the intensity of linkage and the level of inbreeding increases; (2) determine the most efficient method of identifying a homozygous recombinant genotype as the level of inbreeding and linkage intensity are varied. Numerical examples and formula are provided to determine the number of plants that must be grown to have a given probability of success of identifying a specified number of recombinant types. For close linkage, the number of plants that must be genotyped is greatly decreased by waiting until the population is highly inbred.