Presence versus absence of CYP734A50 underlies the style-length dimorphism in primroses

• Published in: eLife Vol. 5
• Main Authors: Huu, Cuong Nguyen, Kappel, Christian, Keller, Barbara, Sicard, Adrien, Takebayashi, Yumiko, Breuninger, Holger, Nowak, Michael D, Bäurle, Isabel, Himmelbach, Axel, Burkart, Michael, Ebbing-Lohaus, Thomas, Sakakibara, Hitoshi, Altschmied, Lothar, Conti, Elena, Lenhard, Michael
• Format: Journal Article
• Language: English
• Published: England eLife Science Publications, Ltd 06.09.2016; eLife Sciences Publications Ltd; eLife Sciences Publications, Ltd
• Subjects: brassinosteroids; Cytochrome P-450 Enzyme System - genetics; Cytochrome P-450 Enzyme System - metabolism; Dimorphism; Dimorphism (Biology); Evolution, Molecular; Flowers & plants; Flowers - anatomy & histology; Gene Duplication; Gene Expression Profiling; Gene Silencing; Genes; Genes and Chromosomes; Haplotypes; heterostyly; Molecular evolution; Mutation; Observations; Outbreeding; Physiological aspects; Plant Biology; Plant Proteins - metabolism; Primroses; Primula; Primula - anatomy & histology; Primula - enzymology; Primula - genetics; Primulaceae; Reproductive organs; S-locus; Short Report; supergene; Primula; S-locus; supergene; brassinosteroids; genes; chromosomes; plant biology; heterostyly
• ISSN: 2050-084X; 2050-084X
• DOI: 10.7554/elife.17956

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.