De novo transcriptome assembly of Angelica dahurica and characterization of coumarin biosynthesis pathway genes

Angelica dahurica (Hoffm.) Benth. & Hook.f. ex Franch. & Sav (A. dahurica) is a famous Chinese herb known for the production of coumarins, important secondary metabolites with wide-ranging pharmacological activities. In particular, the methoxylated coumarins like those produced by A. dahurica are known for their antiinflammatory, anti-cancer, and anti-oxidant pharmacological effects. However, the molecular mechanism of coumarin biosynthesis in A. dahurica has not been studied. Such investigation could help scientists harness the biosynthesis potential of methoxylated coumarins. Here we present, three transcriptomes corresponding to leaf, root, and stem tissues of A. dahurica. A total of 114,310 unigenes with an average length of 1118 bp were de novo assembled, and 81,404 (71.21%) of those unigenes were annotated. Then, 181 unigenes encoding the seven key enzymes involved were identified, for which COMT (Caffeic acid 3-O-methyltransferase) was spatially used in a phylogenetic analysis, and some of these key enzyme genes were verified by qRT-PCR. Differentially expressed genes and root-specific-expressed genes were identified, by comparing genes' profile activity between roots and other tissues. Furthermore, multiple genes encoding key enzymes or transcription factors related to coumarin biosynthesis were identified and analyzed. This study is the first to report comprehensive gene information of A. dahurica at the transcriptional level, and to distinguish candidate genes related to its biosynthesis of coumarin, thus laying a foundation for this pathway's further exploration in A. dahurica.