Sequence evolution in a chromosomal region of Arabidopsis thaliana

Sammanfattning: Recently there has been a lot of interest in the use of liknage disequilibrium (LD) in genome wide scans for new genes, so called association mapping. Of crucial importance to a genome wide scan for associations between genetic markers and the trait of interest is the extent of LD, as it determines both how closely a trait can be mapped and also how many markers is needed to map it. Most outbreeding organisms such as Drosophila melanogaster and maize have too little LD to be useful for association mapping. As LD breaks down much more slowly in predominantly self-fertilising organisms, they can, however, be expected to have much higher levels of LD. It is shown here that the self-fertilising model plant Arabidopsis thaliana holds a lot of promise of being a suitable organism for LD-mapping. Around the flowering time locus FRI, the levels of LD were suitable for LD-mapping. Some of the problems with LD-mapping is also addressed as allelic heterogeneity had a major impact on LD in the region studied. Also some of the basic population genetic parameters for the region are discussed as is geographical subdivision among Arabidopsis thaliana and possible history of the different FRI alleles.