Panax japonicus C.A.Mey, the traditional medicinal herb in the Araliaceae family, has been used as a tonic, anti-inflammatory and haemostatic agent in China for more than thousand years. Its clinical effects are mainly due to the presence of triterpenoid saponins. However, little is known at the genetic level about how saponins are biosynthesized in this plant. We have therefore performed the de novo transcriptome assembly and high throughput RNA-seq analysis for P. japonicus. 66,403 unigenes were assembled from 19.6 Gbp raw data, and 34,639 unigenes were annotated. After annotation, 29 unigen...