TY - JOUR A1 - Cuong Nguyen Huu, A1 - Kappel, Christian A1 - Keller, Barbara A1 - Sicard, Adrien A1 - Takebayashi, Yumiko A1 - Breuninger, Holger A1 - Nowak, Michael D. A1 - Bäurle, Isabel A1 - Himmelbach, Axel A1 - Burkart, Michael A1 - Ebbing-Lohaus, Thomas A1 - Sakakibara, Hitoshi A1 - Altschmied, Lothar A1 - Conti, Elena A1 - Lenhard, Michael T1 - Presence versus absence of CYP734A50 underlies the style-length dimorphism in primroses JF - eLife N2 - Heterostyly is a wide-spread floral adaptation to promote outbreeding, yet its genetic basis and evolutionary origin remain poorly understood. In Primula (primroses), heterostyly is controlled by the S-locus supergene that determines the reciprocal arrangement of reproductive organs and incompatibility between the two morphs. However, the identities of the component genes remain unknown. Here, we identify the Primula CYP734A50 gene, encoding a putative brassinosteroid-degrading enzyme, as the G locus that determines the style-length dimorphism. CYP734A50 is only present on the short-styled S-morph haplotype, it is specifically expressed in S-morph styles, and its loss or inactivation leads to long styles. The gene arose by a duplication specific to the Primulaceae lineage and shows an accelerated rate of molecular evolution. Thus, our results provide a mechanistic explanation for the Primula style-length dimorphism and begin to shed light on the evolution of the S-locus as a prime model for a complex plant supergene. Y1 - 2016 U6 - https://doi.org/10.7554/eLife.17956 SN - 2050-084X VL - 5 PB - eLife Sciences Publications CY - Cambridge ER -