Seymour, D.K. et al. Proc. Natl. Acad. Sci. USA advance online publication (27 February 2012).

For traits that are difficult to map, such as quantitative trait loci that exert small phenotypic effects, geneticists often rely on recombinant inbred lines. Each line is a snapshot of the genomic reshuffling caused by meiotic recombination from a parental cross; inbred progeny are homozygous at nearly all loci so that the makeup of each line does not change in subsequent generations. Unfortunately, inbreeding to fixation takes many generations. Seymour et al. now apply centromere-mediated genome elimination in Arabidopsis thaliana to generate a similar outcome in only two generations. Crossing F1 plants to a centromeric histone mutant produces haploid plants from gametes, which spontaneously develop fertile doubled-haploid offspring. The group showed that the doubled-haploid lines are very similar to recombinant inbred ones and used them to map genes that control flowering time.