摘要：AbstractSelf-incompatibility (SI), which has recurred during the evolution of plants, is one of the most important cross-pollination mating systems. ThreeS-loci have been reported in Brassicaceae, namely,Arabidopsis lyrata(Al),Brassica(Br), andLeavenworthia alabamica(La)S-loci. Here, through multi-genomic comparative analysis of 20 species, we revealed that the most ancientS-locus was formed prior to the divergence of Brassicaceae lineage I and II. It was retained and inherited byArabidopsis,as theAl S-locus in Brassicaceae lineage I. Furthermore, we found that theBr S-locus, which has been widely used in the breeding ofBrassicacrops to generate hybrid seeds, was formed through segmental translocation (ST) in the hexaploid ancestor ofBrassicain Brassicaceae lineage II. TheBr S-locus was evolved through a ST from one of the triplicated ancestralS-locus paralogs in theBrassicahexaploidy ancestor, while the other twoS-locus paralogs were lost. Together with the previous discovery that theLa S-locus was formed through a secondary origin in Brassicaceae lineage I, we conclude the monophyletic origin ofAlandBr S-loci and clarify the evolutionary route ofS-loci in the Brassicaceae family. Our findings will contribute to evolutionary studies and breeding applications of theS-locus in Brassicaceae.
