Molecular phylogeny and evolution of the Asian aconitum subgenus Aconitum (Ranunculaceae)

Classification of the genus Aconitum (Ranunculaceae) has long been considered quite difficult because its species show high levels of morphological and ecological variability. The molecular phylogeny of Asian aconites, Aconitum subgenus Aconitum was, therefore, studied based on RFLP and sequences of the intergenic spacer between the trnL (UAA) 3'exon and trnF (GAA), and of the trnL intron, of the chloroplast DNA. Using Aconitum subgenus Lycoctonum as an outgroup, we obtained a statistically reliable molecular tree composed of six clades branched radiatively at the very base. There are three clades of Japanese aconites, a single clade of the species of Yunnan and Himalayas, and two clades of Siberian plants. All the tetraploid taxa of Japan we studied did not show any difference based on the molecular characters analyzed, though they have been classified into many taxa. Evolution and phytogeography of the Asian aconites as well as the phylogeny are discussed.