2019 Volume 84 Issue 2 Pages 119-126
Random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR) variation among 24 cultivars of four Brassica species (B. rapa, B. juncea, B. napus, and B. oleracea) was examined using individual- and bulked-samples-based approaches. In both the approaches, eight plants were sampled for each cultivar, and were amplified individually and as bulked DNA, respectively. In total, 305 and 422 bands were scored in the individual- and bulked-samples-based approaches, respectively, and almost all the bands (99.8–100%) were polymorphic. Based on the individual-samples dataset, the within cultivar variation was smaller than the among cultivars variation, leading to a distribution reflecting genome compositions of each cultivar with principal coordinates analysis (PCoA) and unweighted pair-group method with arithmetic average (UPGMA) analysis. Although PCoA and UPGMA analysis based on bulked-samples data clustered the cultivars into groups with more emphasized variance among species than the results obtained by the individual-based approach, both PCoA plots and dendrograms of the individual- and bulked-samples-based approaches, respectively, were highly correlated with each other. These findings indicate that the number of individuals used to profile each cultivar can be reduced to eight per cultivar for analysis of the genetic variability in Brassica using RAPD and ISSR polymorphism, and the bulked-samples-based approach can be used to describe the genetic relationship among Brassica cultivars.
