2004 Volume 54 Issue 2 Pages 189-195
In order to gain a better understanding of the genetic basis of the wide differentiations observed in Japanese cultivated radish varieties, structural and sequence variations were studied in the 3′ region of mitochondrial atp6. Three hundred and ninety-four radish plants belonging to eight Chinese, one Korean and 27 Japanese varieties were used as materials, and total DNA was isolated from each plant. Using the DNA as a template, PCRs with three kinds of primer pairs specific to the sequence of normal type cytoplasm were conducted. The radish plants were classified into four types by the combination of amplification patterns based on the three PCRs. Seventy-five percent of the varieties were assigned to one of the four types, and 87 % of the plants were grouped into two types with similar proportions for each (44 and 43 %). Sequence analysis of the plants belonging to the two major types demonstrated that structural rearrangements of the mitochondrial genome had generated the differentiations in the region observed here. The variations in the atp6 3 ′ region corresponded to those of orfB, with a few exceptions. The results indicated the existence of a dual structure of the cytoplasm in Japanese radish cultivars. Additionally, the origin of polymorphic varieties consisting of two or three types was examined.
