Research on the self-incompatibility system in Brassicaceae has been largely carried out using the Brassica genus with species such as Brassica oleracea,Brassica campestris (syn.rapa) and Brassica napus. In this sporophytic homomorphic self-incompatibility system, the incompatible pollen grain is rapidly inhibited at the stigma surface. The recognition and rejection of the self-incompatible pollen is genetically controlled by a single multi-allelic S locus, and the phenotype of the haploid pollen is determined sporophytically by the diploid parent