Expression profiles of flavonoid-related gene, 4 coumarate: coenzyme A ligase, and optimization of culturing conditions for the selected flavonoid production in Boesenbergia rotunda

Knowing 4-Coumarate: coenzyme A ligase (4CL) is one of the important enzymes in the biosynthetic pathway of phenylpropanoid, we studied the gene expression profiles of 4CL and determined the production of selected flavonoids in different parts of Boesenbergia rotunda. The optimal growth conditions for B. rotunda cells were also investigated. In this study, we found that the 4CL transcript was expressed in leaves, rhizomes, and roots with highest expression level found in roots. In contrast, HPLC results showed that the highest total flavonoid contents (pinostrobin, pinocembrin and panduratin A) were recorded in rhizome followed by root and leaf samples. Since rhizome has been found to be a suitable source of explants for in vitro propagation, thus, we initiated sprout from rhizome in order to establish cell suspension cultures. Our study showed that cells grown in full strength Murashige and Skoog basal medium (pH 5.8) containing 1 mg/l 1-napththylacetic acid, 1 mg/l 6-benzyladenine, and 3 % sucrose produced maximal cell biomass and total flavonoid contents. We also found that the 4CL transcript levels for 14- and 10-day old phenylalanine-treated cultures were up-regulated for 22- and 17-fold, respectively, compared to 0-day, indicating the promotive effect of phenylalanine in enhancing the 4CL gene expression. This study provides necessary baseline data for 4CL gene expression profiles and optimal cell culture conditions for the flavonoid production.