Abstract: Self-incompatibility (SI) is one of the most important mechanisms in flowering plants to prevent inbreeding and promoter outcrossing. In Brassica, the diploid varieties of Brassica oleracea (CC) and B. campestris (AA) were self-incompatibility, while the amphidiploid B. napus varieties (AACC) were usually self-compatible. In the SI response, SLG gene was one of the S-locus genes that supposed to contribute to receptor—ligand interactions and signal transduction. SLG gene shares a similarity of 85–98% with eSRK (SRK ectodomain) in the same S haplotype, while in different S haplotypes, the SLGs and SRKs behave dif-ferently. In order to make out whether the S-locus exist in B. napus, the SLG gene in the S-locus in several varieties of B. napus were cloned. By PCR analysis and sequences comparison, the class II SLG gene was found in all tested varieties of B. napus, while class I SLG genes were only found in 5 of the 10 tested varieties. Further studies indicated that the five varieties that had the class I SLG genes were probably derived from the same S haploid years ago. The results would provide scientific reference for further study and exploitation on the mechanistic studies of self-compatibility in Brassica napus L.

Key words: Brassica napus, Self-incompatibility, SLG gene, Homologous analysis