Genetic diversity of Chinese and Japanese rapeseed (Brassica napus L.) varieties detected by RAPD markers

Random amplified polymorphic DNA (RAPD) techniques were employed to estimate the genetic diversity within 13 varieties of Chinese, 26 varieties of Japanese and 11 varieties of Korean, European and Canadian B. napus, A similarity matrix was calculated from 181 polymorphic bands that were amplified with 21 strictly selected PCR primers. Based on the matrix, a phenogram was drawn using the neighbor-joining method, and principal component analysis (PCA) was also carried out with the data of the polymorphic bands. These two analyses enabled to identify a correlation among the varieties and 43 out of 50 varieties were clustered into three major groups. Most of the Japanese and four out of the 13 Chinese cultivars were clustered into one of the three major groups whereas most of the Chinese varieties were not included in the three major groups. European spring and winter types were clustered into two different groups and some of the Asian varieties were included in the groups. Our results also indicate that most of the Chinese and Japanese B. napus varieties in this study showed a unique genetic background that separated them from European varieties.