Abstract: 【Objective】In order to investigate the Genetic diversity and genetic basis of rapeseed (B. napus L.) in China, 【Method】Total 130 accessions developed in different years since 1949 were analyzed using SRAP (sequence-related amplified polymorphism) markers. 【Result】A total of 509 amplified fragments and 123 polymorphic fragments were detected by applying 25 SRAP primer combinations. The polymorphic fragment percentage was 24%. The number of amplified fragments and polymorphic fragments per primer combination were 20.4 and 4.9, respectively. 130 B. napus accessions were divided into four groups of A, B, C and D at genetic distance of 0.12. About 78.5% of total accessions were classified into group C. Group C could also be divided into I, II, III, IV and V sub-groups at genetic distance of 0.10. About 58.5% of total accessions were classified into sub-group I, indicating the genetic diversity of 58.5% accessions of total was poor. The results demonstrated that the genetic basis of B. napus L. accessions released before 1980 was the narrowest while those released in 1980s reached the widest. In 1990s, the genetic distances of B. napus L. accessions declined again. The genetic basis of B. napus L. accessions narrowed further after 2000. Though the difference of mean genetic distance between accessions bred in 1990s and after 2000 did not reach a significant level, the difference in mean genetic distance in different periods was at 0.01 or 0.05 significant level. The difference in mean genetic distance between accessions bred in China and introduced from abroad reached a significant level at 0.01. 【Conclusion】All these results showed that SRAP markers were economic, effective, and reliable.

Key words: B. napus L., SRAP, Genetic diversity, Genetic basis