Classification and characterization of putative cytochrome P450 genes from Panax ginseng C. A. Meyer

Abstract

In plants heme containing cytochrome P450 (P450) is a superfamily of monooxygenases that catalyze the addition of one oxygen atom from O2 into a substrate, with a substantial reduction of the other atom to water. The function of P450 families is attributed to chemical defense mechanism under terrestrial environmental conditions; several are involved in secondary and hormone metabolism. However, the evolutionary relationships of P450 genes in Panax ginseng remain largely unknown. In the present study, data mining methods were implemented and 116 novel putative P450 genes were identified from Expressed Sequence Tags (ESTs) of a ginseng database. These genes were classified into four clans and 22 families by sequence similarity conducted at amino acid level. The representative putative P450 sequences of P. ginseng and known P450 family from other plants were used to construct a phylogenetic tree. By comparing with other genomes, we found that most of the P450 genes from P. ginseng can be found in other dicot species. Depending on P450 family functions, seven P450 genes were selected, and for that organ specific expression, abiotic, and biotic studies were performed by quantitative reverse transcriptase-polymerase chain reaction. Different genes were found to be expressed differently in different organs. Biotic stress and abiotic stress transcript level was regulated diversely, and upregulation of P450 genes indicated the involvement of certain genes under stress conditions. The upregulation of the P450 genes under methyl jasmonate and fungal stress justifies the involvement of specific genes in secondary metabolite biosynthesis. Our results provide a foundation for further elucidating the actual function and role of P450 involved in various biochemical pathways in P. ginseng.

De novo transcriptome sequencing and digital gene expression analysis predict biosynthetic pathway of rhynchophylline and isorhynchophylline from Uncaria rhynchophylla, a non-model plant with potent anti-alzheimer’s properties

“…CYP450 is one of the oldest protein families, has catalytic oxidation function of carbon-carbon bond, alkyl hydroxylation and hydroxyl oxidation, and plays an important role in plant secondary metabolites synthesis process [54–57]. Oxidoreductases involved in RIN and IRN synthesis are therefore likely to come from the CYP450 family.…”

Biosynthesis and biotechnological production of ginsenosides

“…In ginseng plants, among reported ginseng CYP genes (Balusamy et al, 2013;Devi et al, 2011), three CYP genes are involved in ginsenoside biosynthesis, CYP716A47 acts as protopanaxadiol synthase (PPDS) hydroxylating dammarenediol-II at the C-12 position, yielding PPD ; two additional CYP716A subfamily members: CYP716A53v2 as the protopanaxadiol 6-hydroxylase (or called protopanaxatriol synthase, PPTS), catalyzing the generation of PPT from PPD for the synthesis of dammarene-type ginsenosides in P. ginseng , CYP716A52v2 (oleanolic acid synthase, OAS) acting as a β-amyrin 28-oxidase modifying β-amyrin into oleanolic acid for the synthesis of an oleanane-type saponin in P. ginseng (Han et al, 2013). PPDS and PPTS express ubiquitously in all ginseng organs, and the expression of PPDS is promoted by MJ in adventitious roots, but neither for PPTS and OAS .…”

Production of ginseng saponins: elicitation strategy and signal transductions

“…Two molecules of farnesyl diphosphate along with squalene synthase (SS) produce squalene, to which an epoxide group of squalene epoxidase (SE) subsequently gives rise to 2,3-oxidosqualene. Ginsenosides are synthesized from the 2,3-oxidosqualene (a common precursor of sterols), which undergoes additional cyclization, hydroxylation, and glycosylation by dammarenediol synthase (DDS), cytochrome P450, and glycosyltransferase (GT) enzymes, respectively (Han et al 2006;Devi et al 2011;Khorolragchaa et al 2014). Three different groups of ginsenosides have been isolated and identified based on their aglycones: protopanaxadiol-type (PPD) saponins such as ginsenosides Rb1, Rb2, Rc, and Rd; protopanaxatriol-type (PPT) saponins such as ginsenosides Re, Rg1, Rg2, and Rf; and the oleanane group with a pentacyclic structure, and only one ginsenoside, Ro, was identified.…”