The recombination landscape in Arabidopsis thaliana F2 populations

Recombination during meiosis shapes the complement of alleles segregating in the progeny of hybrids, and has important consequences for phenotypic variation. We examined allele frequencies as well as crossover locations and frequencies in over 7000 plants from 17 F2 populations derived from crosses between 18 Arabidopsis thaliana accessions. We observe segregation distortion between parental alleles in over half of our populations. The potential causes of distortion include variation in seed dormancy and lethal epistatic interactions. Such a high occurrence of distortion was only detected here because of the large sample size of each population, and the number of populations characterized. Most plants carry only one or two crossovers per chromosome pair, and therefore inherit very large, non-recombined genomic fragments from each parent. Recombination frequencies vary between populations but consistently increase adjacent to the centromeres. Importantly, recombination rates do not corre...