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Molecular Study of the Genus Caulokaempferia (Zingiberaceae) Distributed along the Mekong
River of Northeastern Thailand and Central Laos
†
Akapoom Chaiyoot*, Suchada Sukrong , Chayan Picheansoonthon*, ‡
*Pharmaceutical Botany and Pharmacognosy Research Unit, Faculty of Pharmaceutical Sciences, Khon Kaen Uni-
versity, Khon Kaen 40002, Thailand
† Department of Pharmacognosy, Pharmaceutical Sciences, Chulalongkorn University, Khet Phayathai, Bangkok
10330, Thailand
‡ Academy of Science, The Royal Institute of Thailand, Sanam Suea Pa, Sri Ayuthaya Rd., Khet Dusit 10300,
Thailand

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.
Key words: molecular study, ribosomal DNA, ITS1-ITS2 region, genus Caulokaempferia, Mekong River in
Thailand and Laos