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BackgroundPanax notoginseng (Burk) F.H. Chen is important medicinal plant of the Araliacease family. Triterpene saponins are the bioactive constituents in P. notoginseng. However, available genomic information regarding this plant is limited. Moreover, details of triterpene saponin biosynthesis in the Panax species are largely unknown.ResultsUsing the 454 pyrosequencing technology, a one-quarter GS FLX titanium run resulted in 188,185 reads with an average length of 410 bases for P. notoginseng root. These reads were processed and assembled by 454 GS De Novo Assembler software into 30,852 unique sequences. A total of 70.2% of unique sequences were annotated by Basic Local Alignment Search Tool (BLAST) similarity searches against public sequence databases. The Kyoto Encyclopedia of Genes and Genomes (KEGG) assignment discovered 41 unique sequences representing 11 genes involved in triterpene saponin backbone biosynthesis in the 454-EST dataset. In particular, the transcript encoding dammarenediol synthase (DS), which is the first committed enzyme in the biosynthetic pathway of major triterpene saponins, is highly expressed in the root of four-year-old P. notoginseng. It is worth emphasizing that the candidate cytochrome P450 (Pn02132 and Pn00158) and UDP-glycosyltransferase (Pn00082) gene most likely to be involved in hydroxylation or glycosylation of aglycones for triterpene saponin biosynthesis were discovered from 174 cytochrome P450s and 242 glycosyltransferases by phylogenetic analysis, respectively. Putative transcription factors were detected in 906 unique sequences, including Myb, homeobox, WRKY, basic helix-loop-helix (bHLH), and other family proteins. Additionally, a total of 2,772 simple sequence repeat (SSR) were identified from 2,361 unique sequences, of which, di-nucleotide motifs were the most abundant motif.ConclusionThis study is the first to present a large-scale EST dataset for P. notoginseng root acquired by next-generation sequencing (NGS) technology. The candidate genes involved in triterpene saponin biosynthesis, including the putative CYP450s and UGTs, were obtained in this study. Additionally, the identification of SSRs provided plenty of genetic makers for molecular breeding and genetics applications in this species. These data will provide information on gene discovery, transcriptional regulation and marker-assisted selection for P. notoginseng. The dataset establishes an important foundation for the study with the purpose of ensuring adequate drug resources for this species.

Salvia miltiorrhiza is a Chinese herb with significant pharmacologic effects because of the bioactive compounds of tanshinones and phenolic acids. Methyl jasmonate (MeJA) has been used as an effective elicitor to enhance the production of these compounds. However, the molecular mechanism of MeJA-mediated tanshinone and salvianolic acid biosynthesis remains unclear. The transcriptional profiles of S. miltiorrhiza leaves at 12 h (T12) after MeJA elicitation and mock-treated leaves (T0) were generated using the Illumina deep RNA sequencing (RNA-seq) strategy to detect the changes in gene expression in response to MeJA. In total, 37 647 unique sequences were obtained from about 21 million reads, and 25 641 (71.53%) of these sequences were annotated based on the blast searches against the public databases. A total of 5287 unique sequences were expressed differentially between the samples of T0 and T12, which covered almost all the known genes involved in tanshinone and phenolic acid biosynthesis in S. miltiorrhiza. Many of the transcription factors (e.g. MYB, bHLH and WRKY) and genes involved in plant hormone biosynthesis and signal transduction were expressed differentially in response to the MeJA induction. Importantly, three and four candidate cytochrome P450s (P450s) that could be involved in the tanshinone and phenolic acid biosynthesis, respectively, were selected from the RNA-seq data based on co-expressed pattern analysis with SmCPS1/SmKSL1 and SmRAS, which are the key genes responsible for biosynthesis. This comprehensive investigation of MeJA-induced gene expression profiles can shed light on the molecular mechanisms of the MeJA-mediated bioactive compound biosynthesis and regulation in S. miltiorrhiza.

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