Investigation on the Phylogenetic Relationship between 'Sugukina' and Turnip (Brassica campestris L.) by RAPD Analysis

Abstract

RAPD (random amplified polymorphic DNA) analysis was applied to strains of 'Sugukina' and turnip varieties (Brassica campestris L.), to clarify the phylogenetic relationship between the two. 'Sugukina' is cultivated traditionally in Kyoto district. DNA fragment patterns of the nine 'Sugukina' strains and the twelve turnip varieties were compared and their relationships were estimated by cluster analysis.
Total DNA was isolated from a leaf of each of the twelve plantlets of the respective strains and varieties, and used as a template of the polymerase chain reactions (PCR). For the PCRs, four kinds of decamer primers were used. Sixty-nine DNA fragments showed the definitive polymorphisms among the 252 plants analyzed, of which 50 bands were selected for comparison. More than 50% of the plants in at least one strain or variety possessed the 50 bands, whereas less than 50% of the plants in another strain or variety had the same bands.
Similarity ratios of the DNA fragment patterns of each 'Sugukina' strain with the other eight strains ranged from 0.40 to 0.56, the average being 0.49. On the other hand, the average similarity ratio value of the 'Sugukina' with the turnip varieties was 0.30. By cluster analysis, all nine 'Sugukina' strains formed a cluster clearly isolating them from another cluster containing all the turnip varieties. In the cluster of the 'Sugukina', seven out of the nine strains were included in two subclusters, but the other two strains possessed the different positions from them.
These results indicate that the 'Sugukina' is a unique group of vegetables, containing large genetic variations and having different genetic characteristics from the turnip varieties growing in Japan.