Self-incompatibility and evolution of mating systems in the Brassicaceae

Abstract

Genetically determined self-incompatibility (SI) systems ensure high rates of out-crossing because they allow the pistil to recognise and reject genetically identical pollen. As such, SI systems are thought to be advantageous because populations with high levels of polymorphism have the genetic variability required for withstanding a wide range of environmental challenges. Nevertheless, SI has repeatedly been lost in plant lineages, and it has been noted that the most frequently travelled path in plant evolution is the path from out-crossing to self-fertility. In this chapter, we focus on the self-incompatibility system of the Brassicaceae and discuss results related to the diversification of the SI recognition repertoire and the various paths that underlie switches to self-fertility in the family.