A RAPD analysis of shoot cadmium accumulating characteristic and tolerance of vegetable cultivars from Brassica genus

13 cultivars of Brassica Chinensis and 11 of B. oleracea were analyzed using Random Amplified Polymorphic DNA (RAPD) markers to investigate the pattern of genetic variation related to Cd accumulation and tolerance of shoot under Cd stress. 31 well-amplified and highly reproductive polymorphic bands by 5 of total 8 random primers were scored, with length between 100～2000bp. Two polygenic trees, of B. Chinensis and B. oleracea, respectively, computed using micro-evolution method show that the cultivars with high shoot Cd accumulation present tight clustering tendence, and it is of highly significant linear regression between the shoot Cd content and their correspondingly genetic distance. The genetic diversity is found higher in subgroup of high shoot Cd content than that in subgroup of low shoot Cd content. Analysis of Molecular Variance (AMOVA) of the RAPD markers give highly statistical significance to the subgroupings of populations according to the shoot Cd content, indicating that RAPD markers detect a polymorphism related to the Cd accumulation. Finally, two RAPD bands, one for B. chinensis (350bp), another for B. oleracea (410bp), presented in high shoot Cd content subgroup, but exclusive to the low one are identified.