ITS sequences of some Acer species and phylogenetic implication

Abstract

Sequences of internal transcribed spacers (ITS) of nuclear ribosomal DNA were determined to study phylogenetic relationships among selected sections of the genus Acer. The size of ITS 1 ranged from 230 to 237 bp, and ITS 2 from 227 to 239 bp. The 5.8S was 164 bp. The G+C contents of ITS 1 and 2 were 60.4-64.0% and 60.3-63.8%, respectively and 55.5% for 5.8S. The value of nucleotide divergences was 0-11.50% at intra-sectional level and 3.27-16.51% at intersectional level. The molecular phylogeny based on ITS sequences was considerably different from ones proposed by previous authors on the basis of morphological and chemical features. Section Platanoidea was separated from other sections at the base of the phylogenetic tree and then sect. Macrantha was placed at the base among the remains. Sections Negundo and Caudata constituted a clade, serving as a sister group of 'Ginnala'-Oblonga-Palmata' clade. Section Ginnala was placed as the sister group of 'Oblonga-Palmata' clade. I!