Petunia inflata utilizes self-incompatibility (SI) to prevent self-fertilization and consequent inbreeding. S-Locus F-box (SLF) proteins control pollen function in SI. Each SLF is part of the SCFSLF complex that contains either PiCUL1-P, or PiCUL1-B, as the CUL subunit. I found that the level of a GFP-fused SLF protein in mutants with both CUL1 genes knocked out was extremely low, suggesting that the integrity of the SCFSLF complex is essential for the stability of SLF proteins.