Figure 1 .
Scheme of model differences for self-incompatible species with a S-Z system. Model I: any different allele at either S or Z in the pollen different from S or Z on the pistil makes pollen is compatible. Model II: any S-Z allele combination present in the pollen grain that matches the pistil makes pollen incompatible.
Aguirre et al. BMC Bioinformatics 2012 13:125 doi:10.1186/1471-2105-13-125