Figure 8.

Schematic model for self-pollen recognition in Brassica species. Male and female S determinant genes, SP11 and SRK, are located at the S locus. SP11 is predominantly expressed in the tapetum cells of anther locules, and accumulates on the pollen surface during pollen maturation. On self-pollination, SP11 molecules penetrate into the papilla cell wall, and interact with SRK in an S-allele-specific manner. Phosphorylated SRK interacts with MLPK. After the subsequent signal transduction, which has not yet been determined, rejection of the self-pollen occurs.