Pollen–pistil interactions are an essential prelude to fertilization in angiosperms, and self-incompatibility (SI) is the best understood of these at a molecular level. Allen et al. review studies in the Asteraceae, and consider that recent cellular and molecular work in Senecio squalidus (Oxford ragwort) have challenged the belief that sporophytic SI and pollen–pistil interactions in Asteraceae and Brassicaceae are similar. The availability of a pool of pistil-specific genes for S. squalidus offers an opportunity to elucidate the molecular mechanisms of pollen–pistil interactions and SI in the Asteraceae.
