Molecular biology of self-incompatibility in Brassica species

Many angiosperm plants express self- incompatibility (SI), through which they can recognize selfpollen and restrict fertilization to non-self-pollen. In species of Brassica, SI is sporophytically expressed, regulated by a single locus, S, with multiple alleles. Two stigma- specific genes, SLG and SRK, both of which locate at the S locus, are believed to play a role in the recognition reaction on the stigma side. Reviewed here are findings about SLG and SRK genes, the molecular characterization of Smultigene family, the genomic structure of S locus, and some aspects on signal transfer by the proteins encoded by these genes.