title: Analysis of the transcriptome of Panax notoginseng root uncovers putative triterpene saponin-biosynthetic genes and genetic markers.
abstract: BACKGROUND
  Panax 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.
  
  
  RESULTS
  Using 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.
  
  
  CONCLUSIONS
  This 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.
authors.affiliation: The Key Laboratory of Bioactive Substances and Resources Utilization of Chinese Herbal Medicine, Ministry of Education, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193, PR China.
authors.forename: Hongmei
authors.initials: H
authors.lastname: Luo
authors.forename: Chao
authors.initials: C
authors.lastname: Sun
authors.forename: Yongzhen
authors.initials: Y
authors.lastname: Sun
authors.forename: Qiong
authors.initials: Q
authors.lastname: Wu
authors.forename: Ying
authors.initials: Y
authors.lastname: Li
authors.forename: Jingyuan
authors.initials: J
authors.lastname: Song
authors.forename: Yunyun
authors.initials: Y
authors.lastname: Niu
authors.forename: Xianglin
authors.initials: X
authors.lastname: Cheng
authors.forename: Hongxi
authors.initials: H
authors.lastname: Xu
authors.forename: Chuyuan
authors.initials: C
authors.lastname: Li
authors.forename: Juyan
authors.initials: J
authors.lastname: Liu
authors.forename: André
authors.initials: A
authors.lastname: Steinmetz
authors.forename: Shilin
authors.initials: S
authors.lastname: Chen
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D003577:Cytochrome P-450 Enzyme System / Q000145:classification / Q000235:genetics; D030541:Databases, Genetic; D020224:Expressed Sequence Tags; D005819:Genetic Markers / Q000235:genetics*; D016695:Glycosyltransferases / Q000145:classification / Q000235:genetics; D018895:Microsatellite Repeats; D008969:Molecular Sequence Data; D053723:Panax notoginseng / Q000235:genetics*; D010802:Phylogeny; D018517:Plant Roots / Q000235:genetics; D012503:Saponins / Q000096:biosynthesis / Q000235:genetics*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D059467:Transcriptome
chemical_list: D005819:Genetic Markers; D012503:Saponins; D003577:Cytochrome P-450 Enzyme System; D016695:Glycosyltransferases; D019883:Alkyl and Aryl Transferases; C514651:dammarenediol-II synthase, Panax ginseng