Genetic diversity of Amomum xanthioides and its related species from Southeast Asia and China

Amomum Semen, the seed mass of Amomum xanthioides, has been imported from Southeast Asia and China and used for the treatment of gastric and intestinal disorders. A. xanthioides has been treated as a synonym of A. villosum var. xanthioides. Furthermore, A. villosum var. villosum, A. villosum var. xanthioides, or A. longiligulare have been described as the botanical origin of Amomi Fructus, which is a similar crude drug in Chinese Pharmacopoeia. Under these circumstances, the botanical origin of Amomum Semen was changed to A. villosum var. xanthioides, A. villosum var. villosum, or A. longiligulare in Supplement II to the 17th edition of the Japanese Pharmacopoeia. To develop an objective identification method for Amomum Semen and to confirm the phylogenetic relationship among Amomum taxa, the nucleotide sequences of the nuclear ribosomal DNA internal transcribed spacer region and chloroplast DNA partial matK-trnK and trnH-psbA intergenic spacer regions were determined in specimens collected from Southeast Asia and China, including those from the type localities of each taxon. Six taxa were divided into four groups. A. xanthioides from Myanmar belonging to group 1 was discriminated from A. villosum var. xanthioides from China of group 2. A. villosum and its varieties were divided into two groups: group 2 included those from China, and group 3 consisted of A. villosum from Laos. A. longiligulare from China and Laos and A. uliginosum from Laos belonged to group 3 and group 4, respectively. These findings illustrate the phylogenetic basis for the need for taxonomical reorganization among the Amomum species.