Phylogenetic analysis of Japanese Rosaspecies using DNA sequences of nuclear ribosomal internal transcribed spacers (ITS)

Abstract

SummaryThe internal transcribed spacers (ITS) region of 18-26S nuclear ribosomal DNA was sequenced in each of the 15 Japanese Rosa taxa, 14 other Asian taxa and one American taxon to analyse their phylogenetic relationships. Alignment of all ITS region sequence positions including 5.8S rDNA resulted in a matrix of 638 base pairs. The length of the entire ITS region varied among the DNAs from 624 to 629bp. ITS1 ranged from 253 to 255 bp, while ITS2 ranged from 207 to 211 bp. All 13 tested taxa in the section Synstylae formed one clade. This indicates that the section Synstylae, with the common connate styles exserting from hypanthium, is probably monophyletic. Furthermore, three species in this section, R. moschata, R. henryi and R. sambucina, formed an inner clade which is consistent with their common morphological traits. In contrast, the section Rosa was separated into several different clades: two clones of R. acicularis allied with two taxa (R. roxburghii var. normalis and R. roxburghii var. hirtula) in the subgenus Platyrhodon and R. laevigata in the section Laevigatae into one clade, R. marretii and R. rugosa into another one, while R. acicularis var. nipponensis was separated from its mother species and failed to form a clade with any of the species. Sections Indicae and Banksianae each formed a single clade. These results suggest that the traditional subgenus Rosa and the relationship between the subgenus Rosa and the subgenus Platyrhodon should be reexamined. Further studies are needed to verify our results.