TY - JOUR T1 - Patterns of polymorphism at the self-incompatibility locus in 1,083 <em>Arabidopsis thaliana</em> genomes JF - bioRxiv DO - 10.1101/098228 SP - 098228 AU - Takashi Tsuchimatsu AU - Pauline M. Goubet AU - Sophie Gallina AU - Anne-Catherine Holl AU - Isabelle Fobis-Loisy AU - Héléne Bergés AU - William Marande AU - Elisa Prat AU - Dazhe Meng AU - Quan Long AU - Alexander Platzer AU - Magnus Nordborg AU - Xavier Vekemans AU - Vincent Castric Y1 - 2017/01/01 UR - http://biorxiv.org/content/early/2017/01/04/098228.abstract N2 - Although the transition to selfing in the model plant Arabidopsis thaliana involved the loss of the self-incompatibility (SI) system, it clearly did not occur due to the fixation of a single inactivating mutation at the locus determining the specificities of SI (the S-locus). At least three groups of divergent haplotypes (haplogroups), corresponding to ancient functional S-alleles, have been maintained at this locus, and extensive functional studies have shown that all three carry distinct inactivating mutations. However, the historical process of loss of SI is not well understood, in particular its relation with the last glaciation. Here, we took advantage of recently published genomic re-sequencing data in 1,083 Arabidopsis thaliana accessions that we combined with BAC sequencing to obtain polymorphism information for the whole S-locus region at a species-wide scale. The accessions differed by several major rearrangements including large deletions and inter-haplogroup recombinations, forming a set of haplogroups that are widely distributed throughout the native range and largely overlap geographically. ‘Relict’ A. thaliana accessions that directly derive from glacial refugia are polymorphic at the S-locus, suggesting that the three haplogroups were already present when glacial refugia from the last Ice Age became isolated. Inter-haplogroup recombinant haplotypes were highly frequent, and detailed analysis of recombination breakpoints suggested multiple independent origins. These findings suggest that the complete loss of SI in A. thaliana involved independent self-compatible mutants that arose prior to the last Ice Age, and experienced further rearrangements during post-glacial colonization. ER -