De novo Transcriptome Assembly and Characterization of Medicinally Important Swertia japonica

Swertia japonica, one of the important member of traditional Japanese medicine, possess unique medicinal properties. Metabolite extracts from this plant have been described to possess a characteristic bitter taste, and have potential applications for febrifuge and anthelmintic, tonic, anti-periodic, cathartic, stomachic, asthma, leucorrhoea, analeptic, mitigate inflammation, and relaxing the pregnant uterus. Despite of such diverse medicinal potential, little is known about its molecular basis due to the lack of genomic and transcriptomic resources. Here, we present deep-transcriptome sequencing for the aerial tissues and the roots of S. japonica. S. japonica de novo transcriptome assembly was obtained by using a combined approach of three popular transcriptome assemblers, yielding 81,729 unigenes having an average length of 884 bps and N50 value of 1452 bps, of which 46,963 unigenes were annotated based on the sequence similarity against NCBI-nr protein database. Transcript abundance analysis, gene ontology enrichment analysis, and KEGG pathway enrichment analysis revealed metabolic processes being up-regulated in the aerial tissues with respect to the roots of S. japonica. Being the first report of transcriptome assembly and annotation for any of the Swertia species, this study will be a valuable resource for future investigations on the biosynthetic pathways of therapeutic metabolites and their regulations.

Rai A¹, Nakamura M¹, Takahashi H², Suzuki H³, Saito K¹ and Yamazaki M¹

¹Graduate School of Pharmaceutical Sciences, Chiba University, Inohana 1-8-1, Chuo-ku, Chiba, 260-8675, Japan.

²Medical Mycology Research Center, Chiba University, Chiba, Japan.

³Department of Research and Development, Kazusa DNA Research Institute, Chiba, Japan.