Cullin1 is a component of the SCF-ubiquitin ligase, however previous studies were not able to pinpoint which paralog(s) of Cullin1 participate(s) in SCFSLF, the pollen-S machinery in S-RNase-based self-incompatibility (SI). Kubo et al (on pp.2403-2416) identified five Cullin1s, and showed that CUL1-P is the essential component of SCFSLF in Petunia (Solanaceae) by in vitro and in vivo protein-interaction assays and amiRNA-mediated knockdown experiments. Further, the absence of a CUL1-P ortholog in Rosaceae suggests that SI machineries have been acquired independently in Solanaceae and Rosaceae, despite both families sharing the S-RNase-based SI system.