title: Genetic architecture and evolution of the S locus supergene in Primula vulgaris.
abstract: Darwin's studies on heterostyly in Primula described two floral morphs, pin and thrum, with reciprocal anther and stigma heights that promote insect-mediated cross-pollination. This key innovation evolved independently in several angiosperm families. Subsequent studies on heterostyly in Primula contributed to the foundation of modern genetic theory and the neo-Darwinian synthesis. The established genetic model for Primula heterostyly involves a diallelic S locus comprising several genes, with rare recombination events that result in self-fertile homostyle flowers with anthers and stigma at the same height. Here we reveal the S locus supergene as a tightly linked cluster of thrum-specific genes that are absent in pins. We show that thrums are hemizygous not heterozygous for the S locus, which suggests that homostyles do not arise by recombination between S locus haplotypes as previously proposed. Duplication of a floral homeotic gene 51.7 million years (Myr) ago, followed by its neofunctionalization, created the current S locus assemblage which led to floral heteromorphy in Primula. Our findings provide new insights into the structure, function and evolution of this archetypal supergene.
authors.affiliation: School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.|John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
authors.forename: Jinhong
authors.initials: J
authors.lastname: Li
authors.affiliation: School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.|John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Cocker
authors.affiliation: The Earlham Institute, Norwich Research Park, Norwich NR4 7UH, UK.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Wright
authors.affiliation: School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.|John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Webster
authors.affiliation: The Earlham Institute, Norwich Research Park, Norwich NR4 7UH, UK.
authors.forename: Mark
authors.identifier: 0000-0002-0711-5666
authors.initials: M
authors.lastname: McMullan
authors.affiliation: The Earlham Institute, Norwich Research Park, Norwich NR4 7UH, UK.
authors.forename: Sarah
authors.initials: S
authors.lastname: Dyer
authors.affiliation: The Earlham Institute, Norwich Research Park, Norwich NR4 7UH, UK.
authors.forename: David
authors.initials: D
authors.lastname: Swarbreck
authors.affiliation: The Earlham Institute, Norwich Research Park, Norwich NR4 7UH, UK.
authors.forename: Mario
authors.initials: M
authors.lastname: Caccamo
authors.affiliation: School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.
authors.forename: Cock van
authors.initials: CV
authors.lastname: Oosterhout
authors.affiliation: School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.|John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
authors.forename: Philip M
authors.initials: PM
authors.lastname: Gilmartin
mesh_terms: D019143:Evolution, Molecular; D035264:Flowers / Q000033:anatomy & histology / Q000235:genetics*; D017343:Genes, Plant; D031825:Primula / Q000033:anatomy & histology / Q000235:genetics*