PT  - JOURNAL ARTICLE
AU  - Juanita Gutiérrez-Valencia
AU  - Marco Fracassetti
AU  - Emma L. Berdan
AU  - Ignas Bunikis
AU  - Lucile Soler
AU  - Jacques Dainat
AU  - Verena E. Kutschera
AU  - Aleksandra Losvik
AU  - Aurélie Désamoré
AU  - P. William Hughes
AU  - Alireza Foroozani
AU  - Benjamin Laenen
AU  - Edouard Pesquet
AU  - Mohamed Abdelaziz
AU  - Olga Vinnere Pettersson
AU  - Björn Nystedt
AU  - Adrian Brennan
AU  - Juan Arroyo
AU  - Tanja Slotte
TI  - Genomic analyses of the <em>Linum</em> distyly supergene reveal convergent evolution at the molecular level
AID  - 10.1101/2022.05.27.493681
DP  - 2022 Jan 01
TA  - bioRxiv
PG  - 2022.05.27.493681
4099  - http://biorxiv.org/content/early/2022/05/29/2022.05.27.493681.short
4100  - http://biorxiv.org/content/early/2022/05/29/2022.05.27.493681.full
AB  - Supergenes govern balanced polymorphisms in a wide range of systems. The reciprocal placement of stigmas and anthers in pin and thrum floral morphs of distylous species constitutes an iconic example of a balanced polymorphism governed by a supergene, the distyly S-locus. Recent studies have shown that the Primula and Turnera distyly supergenes are both hemizygous in thrums, but it remains unknown if hemizygosity is pervasive among distyly S-loci. Here we have characterized the genetic architecture and evolution of the distyly supergene in Linum by generating a chromosome-level genome assembly of Linum tenue, followed by the identification of the S-locus using population genomic data. We show that hemizygosity and thrum-specific expression of S-linked genes, including a pistil-expressed candidate gene for style length, are major features of the Linum S-locus. Structural variation is likely instrumental for recombination suppression, and although the non-recombining dominant haplotype has accumulated transposable elements, S-linked genes are not under relaxed purifying selection. Our findings reveal remarkable convergence in the genetic architecture and evolution of independently derived distyly supergenes. The chromosome-level genome assembly and detailed characterization of the distyly S-locus in L. tenue will facilitate elucidation of molecular mechanisms underlying the different forms of flowers described by Darwin.Competing Interest StatementThe authors have declared no competing interest.