Genome of selfing Siberian Arabidopsis lyrata explains establishment of allopolyploid Arabidopsis kamchatica

Abstract

AbstractIn outcrossing plants a lack of mating partners at range edges or resulting from karyotypic changes can be alleviated by a transition to self-compatibility. Here we determine the genetics of this transition in diploid Siberian Arabidopsis lyrata and allotetraploid A. kamchatica. We first provide chromosome-level genome assemblies for one Siberian and one North American selfing A. lyrata accession, and then give the structure of a fully assembled S-locus in the Siberian accession. We then reconstruct the events leading to the loss of self-incompatibility in Siberian A. lyrata and date it to ∼140 Kya, showing it was an independent transition to selfing from that of North American A. lyrata. Moreover, using both A. lyrata genomes we detect segregating structural variants up to ∼2.4 Mb in size. Finally, we show that this selfing Siberian A. lyrata lineage is parental to allotetraploid A. kamchatica and explain the selfing of the latter by the dominant loss-of-function mutation in the S-locus inherited from A. lyrata. This suggests that transition to self-compatibility in one of the parental lineages promoted the establishment of the new allotetraploid A. kamchatica.