The origin of wild populations of Toxicodendron succedaneum on mainland Japan revealed by genetic variation in chloroplast and nuclear DNA

Toxicodendron succedaneum: (L.) Kuntze is a tree cultivated for the production of sumac wax, which is extracted from the mesocarp. There are several hypotheses regarding the origin of T. succedaneum on mainland Japan. In this study, the geographical distribution of genetic variation in 13 wild populations on Honshu, Shikoku, Kyushu, and Ryukyu Islands, Japan was investigated and compared with that of individuals from continental Asia. Seven chloroplast DNA haplotypes of T. succedaneum were observed in Japan and could be divided into three lineages based on relatedness between haplotypes. One of these lineages was also observed in continental Asia, and the others were genetically distant from the haplotypes that originated on the continent, with one considered to have originated on the Ryukyu Islands, and the other on mainland Japan. The genetic diversity of both chloroplast and nuclear DNA was lower in populations from Ryukyu Islands than in populations from mainland Japan. Bayesian clustering based on nuclear genotypes showed a clear difference between the groups from Ryukyu Islands and mainland Japan. Based on approximate Bayesian computation analysis of polymorphic data for both genomes, it was inferred that wild populations of T. succedaneum on mainland Japan consist of both lineages with natural distribution on mainland Japan and those introduced from Ryukyu Islands and continental Asia.