Analysis of expressed sequence tags from Centella asiatica (L.) Urban hairy roots elicited by methyl jasmonate to discover genes related to cytochrome P450s and glucosyltransferases

Centella asiatica (L.) Urban, which is a perennial plant in the family Umbelliferae, is commercially utilized as a wound-healing agent, due to its potent anti-inflammatory effects. Despite the medicinal importance of C. asiatica, little genomic or transcriptomic data are available from the public databases. To identify the genes involved in biosynthesis of these materials, an expressed sequence tag (EST) analysis was performed from C. asiatica hairy roots after methyl jasmonate (MJ) treatment as an elicitor. Sequencing of 4,896 cDNA clones generated 4,381 5'-end high-quality ESTs (GenBank Accession Number JK513929-JK518371, average length 625.8 bp), of which 2,837 (376 contigs and 2,461 singletons) were revealed to be unique by sequence comparison, and 978 (34.4 % of total clusters) had a putative ATG start codon. A total of 2,420 unique sequences were annotated by a BLAST similarity search. Asiatic acid and madecassic acid, as precursors of asiaticoside and madecassoside, respectively, were biosynthesized from alpha-amyrin by cytochrome P450 hydroxylase and carboxylase (P450). Two centellosides were catalyzed from asiatic acid and madecassic acid by UDP-glucosyltransferases (UGTs). We identified 24 P450 and 13 UGT candidates from the database. Finally, 3 of the P450s and 1 UGT were selected as candidates most likely to be involved in centelloside biosynthesis in a MJ inducibility experiment based on a real-time reverse transcription-polymerase chain reaction assay. This is the first report on the use of EST analysis to study the gene expression profiles in C. asiatica hairy roots elicited by MJ.