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Platycodon grandiflorum is a herbal flowering perennial plant belongs to Campanulaceae family. The saponins derived from P. grandiflorum were termed platycosides and platycodin D, which is the most abundant saponin in the plant and pharmacologically active component, was intensively studied. Platycodin D is synthesized from triterpenoids by several enzymes including cytochrome P450. Cytochrome P450 is known to exist in superfamily in plant kingdom and essential roles in saponin biosynthetic pathway by hydroxylation or oxidation of triterpene skeletons. However, the key genes of P450 involved in biosynthesis of saponin was not identified because of its low conservation rate in amino acid sequence level among plant species and gene superfamilies. Recently, next generation sequencing (NGS) technology is rapidly developed as a method to discover target genes. In this study, we tried to identify P450 genes involved in saponin biosynthetic pathway from the various tissues of P. grandiflorum using RNA-seq analysis. The sequencing was performed using Illumina Hi-Seq platform after cDNA library preparation. The produced reads were assembled using CLC Genomics Workbench software (CLC Bio, Inc.). We obteined 122,663 contigs and found out 191 putative P450 genes. The phylogenetic relationship was analyzed and putative genes related to platicoside biosysthesis were selected and cloned for further analysis.
