Regulatory Genes Control a Key Morphological and Ecological Trait Transferred Between Species

TLDR

Hybridization between species can lead to introgression of genes, providing a mechanism for preserving and recombining key traits during evolution. The study analyzes a natural flower‑head polymorphism in Senecio to determine the molecular basis of such gene transfer. The authors examined this polymorphism and found that the RAY regulatory gene cluster, expressed in the peripheral inflorescence meristem, promotes flower asymmetry and increases outcrossing. The polymorphism arose from introgression of the RAY gene cluster from S.

Abstract

Hybridization between species can lead to introgression of genes from one species to another, providing a potential mechanism for preserving and recombining key traits during evolution. To determine the molecular basis of such transfers, we analyzed a natural polymorphism for flower-head development in Senecio. We show that the polymorphism arose by introgression of a cluster of regulatory genes, the RAY locus, from the diploid species S. squalidus into the tetraploid S. vulgaris. The RAY genes are expressed in the peripheral regions of the inflorescence meristem, where they promote flower asymmetry and lead to an increase in the rate of outcrossing. Our results highlight how key morphological and ecological traits controlled by regulatory genes may be gained, lost, and regained during evolution.