ITS SEQUENCES AND SPECIATION ON FAR-EASTERN INDIGOFERA (LEGUMINOSAE)

The internal transcribed spacer (ITS) regions of 18-26S nuclear riboso mal DNA was sequenced to address phylogenetic relationships and to mea sure the extent of differentiation among six species of the Far Easter n Indigofera. ITS 1 had 230-240 base pairs (bp) long while ITS 2 had 2 11-213 bp long. The 5.8S rRNA coding region was 161 bp long. Sequence divergence calculated by Kimura's two parameter method between species ranged from 0.00 to 13.49%. A single most parsimonious tree was produ ced from 77 variable nucleotide sites, which had a consistency index o f 0.97 and a retention index of 0.83. ITS sequence data suggested that the continental species of I. kirilowii (2n=16) is diverged from the common ancestor of other species at first, and then the island species of I. decora (2n=48) and I. venulosa and the Korean Peninsular specie s of I. grandiflora (2n=16) and I. koreana (2n=32) are diverged from t he ancestor. The molecular data supports that the speciation in the Fa r Eastern Indigofera occurred with polyploidization from continental a ncestor to peripheral peninsular and island species.