Differentiation of the Cytoplasm of Japanese Cultivated Radishes (Raphanus sativus) into Four Types in the 3' Region of Mitochondrial Atp6

Abstract

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.

Inter‐ and intraspecific sequence variations of the chloroplast genome in wild and cultivated Raphanus

“…Among the plant materials, four wild and four cultivated radishes (‘RS15‐1’, ‘Hamasaka‐1’, ‘Kakizaki‐1’, ‘Shirahama‐1’, ‘Daibaika’, ‘Sobaika‐Kansaito’, ‘MS‐Gensuke’ and ‘Sabaka’) are known to have Ogura male‐sterile cytoplasm from our previous experiments, whereas the other 51 plants possess normal cytoplasm. The seed sources of the radish materials used here were same as those described in our previous papers (Yamagishi and Terachi 2003, Yamagishi 2004, Yamagishi and Sasaki 2004).…”

“…In the course of the above studies, nucleotide sequence variations in orf138 of the Ogura cytoplasm, and structural and sequence variations in various mt genes of normal cytoplasm were discovered (Terachi et al. 2001, Yamagishi and Terachi 2001, 2003, Yamagishi and Sasaki 2004). Based on the investigations of the mt genome, relationships between wild and cultivated radishes and the origins of cultivated species were defined (Yamagishi and Terachi 2003, Yamagishi 2004).…”