Phylogeographic Analyses of Angelica dahurica (Apiaceae) in Japan and Korea: Insights into the Indigenous Status of Japanese Wild Populations

Abstract

The population genetic structure and diversity of Angelica dahurica were investigated in wild populations from Japan and Korea, as well as in Japanese cultivars, using genome-wide SNPs. Phylogenetic network and population structure analyses identified three distinct geographic groups: Honshu, Kyushu, and Korea. Most Japanese cultivars maintained in medicinal plant gardens and nurseries were assigned to one of these three groups, although one strain could not be definitively classified. Genetic diversity within populations did not significantly differ between wild populations in Japan and Korea; however, average genetic diversity at the geographic group level tended to be higher in Korea than in Japan. These findings suggest that A. dahurica populations in Japan are likely indigenous, contrary to some views that they originated from cultivated individuals used for medicinal purposes, although this possibility cannot be entirely ruled out. The population genetic structure and diversity of this species were likely influenced by distributional changes during Pleistocene climate oscillations, as observed in many temperate plant species in Japan. Further field surveys of wild populations in Japan and Korea are needed to better understand the lower genetic diversity at the geographic group level in Japan.