Molecular Study of the Genus Caulokaempferia (Zingiberaceae) Distributed along the Mekong River of Northeastern Thailand and Central Laos

Abstract

Caulokaempferia is a genus of the ginger family (Zingiberaceae). Some taxa of this genus distributed along the Mekong River of northeastern Thailand and central Laos are used medicinally by forest monks. This study was aimed at demonstrating molecular information as a character, apart from morphological
characters, to confirm species distinction between the five morphologically closely related Caulokaempferia taxa native to the Mekong River basin in northeastern Thailand and Laos: C. bracteata K. Larsen & S.S. Larsen, C. jirawongsei Picheans & Mokkamul), C. phulangkaensis Picheans., C. phutokensis Picheans., and C. phuwoaensis Picheans. & Koonterm. The phylogenetic tree based on the nucleotide sequences of the ITS1-ITS2 region of the ribosomal DNA from all five species was constructed, with C. saxicola K. larsen (AF478732) as an out group, and their corresponding base sequences were compared. The result clearly indicates that these five species are closely related, but distinct. This molecular information complies with the morphological and biogeographical characters of these five species.