Genome-wide high-resolution mapping by recurrent intermating using Arabidopsis thaliana as a model

We demonstrate a method for developing populations suitable for genome- wide high-resolution genetic linkage mapping, by recurrent intermating among F₂ individuals derived from crosses between homozygous parents. Comparison of intermated progenies to F₂ an 'recombinant inbred' (RI) populations from the same pedigree corroborate theoretical expectations that progenies intermated for four generations harbor about threefold more information for estimating recombination fraction between closely linked markers than either RI-selfed or F₂ individuals (which are, in fact, equivalent in this regard). Although intermated populations are heterozygous, homozygous 'intermated recombinant inbred' (RI) populations can readily be generated, combining additional information afforded by intermating with the permanence of RI populations. Intermated populations permit fine-mapping of genetic markers throughout a genome, helping to bridge the gap between genetic map resolution and the DNA-carrying capacity of modern cloning vectors, thus facilitating merger of genetic and physical maps. Intermating can also facilitate high- resolution mapping of genes and QTLs, accelerating map-based cloning. Finally, intermated populations will facilitate investigation of other fundamental genetic questions requiring a genome-wide high-resolution analysis, such as comparative mapping of distantly related species, and the genetic basis of heterosis.