Assessment of the congruity of genetic relationships and variation revealed by individual- and bulked-samples-based approaches using RAPD and ISSR markers in Japanese turnip (Brassica rapa ssp. rapa) cultivars

摘要

To find out an efficient and accurate way to estimate the genetic relationship among cultivars having within-variety genetic variation by using different types of approaches, we compared among-varieties genetic similarity estimated based on individual samples and also on bulked population samples of six Japanese turnip (Brassica rapa ssp. rapa) cultivars using RAPD and ISSR markers. In both individual- and bulked-samples-based approaches, 37 individuals were sampled from each cultivar, amplified individually and also as bulked DNA, respectively. Genetic similarity matrices among six cultivars were estimated based on four similarity measures estimated with 125 or 124 polymorphic bands scored in the individual- or bulked-samples-based approach, respectively, and the correlations between the similarity matrices were calculated to evaluate the degree of agreement between matrices. Correlations between similarity matrices calculated based on individuals on the one hand and those calculated based on bulked samples on the other were also high and significant in all combinations of the four similarity measures. Use of computational analysis indicated that 6 to 8 individuals per cultivar were enough to accurately estimate similarity with the individual-based approach.