The Snapdragon Genomes Reveal the Evolutionary Dynamics of the S-Locus Supergene. (4th April 2023) - Zhu, Sihui
Abstract: The genus Antirrhinum has been used as a model to study self-incompatibility extensively. The multi-allelic S -locus, carrying a pistil S-RNase and dozens of S -locus F-box ( SLF ) genes, underlies the genetic control of self-incompatibility (SI) in Antirrhinum hispanicum . However, there have been limited studies on the genomic organization of the S -locus supergene due to a lack of high-quality genomic data. Here, we present the chromosome-level reference and haplotype-resolved genome assemblies of a self-incompatible A. hispanicum line, AhS7 S8 . For the first time, 2 complete A. hispanicum S -haplotypes spanning ∼1.2 Mb and containing a total of 32 SLFs were reconstructed, whereas most of the SLFs derived from retroelement-mediated proximal or tandem duplication ∼122 Mya. Back then, the S -RNase gene and incipient SLFs came into linkage to form the pro-type of type-1 S -locus in the common ancestor of eudicots. Furthermore, we detected a pleiotropic cis -transcription factor (TF) associated with regulating the expression of SLF s, and two miRNAs may control the expression of this TF. Interspecific S -locus and intraspecific S -haplotype comparisons revealed the dynamic nature and polymorphism of the S -locus supergene mediated by continuous gene duplication, segmental translocation or loss, and TE-mediated transposition events. Our data provide an excellent resource for future research on the evolutionary studies of the S-RNase -based self-incompatibility system.