Transcript Pattern of Cytochrome P450, Antioxidant and Ginsenoside Biosynthetic Pathway Genes Under Heavy Metal Stress in Panax ginseng Meyer

Abstract

The differential transcript patterns of five antioxidant genes, four genes related to the ginsenoside pathway and five P450 genes related to defense mechanism were investigated in in vitro adventitious roots of Panax ginseng after exposure to two different concentrations of heavy metals for 7 days. PgSOD-1 and PgCAT transcription increased in a dose-dependent manner during the exposure to CuCl(2), NiCl(2), and CdCl(2), while all other tested scavenging enzymes didn't show significant increase during heavy metal exposure. Conversely, the mRNA transcripts of PgSQE, PgDDS were highly responsive to CuCl(2) compared to NiCl(2) exposure. However, the transcript profile of Pgβ-AS was highly induced upon NiCl(2) treatment compared to CuCl(2) and CdCl(2) exposure. The expressions of PgCYP716A42, PgCYP71A50U, and PgCYP82C22 were regulated in similar manners, and all showed the highest transcript profile at 100 μM of CuCl(2), CdCl(2), and NiCl(2) except PgCYP71D184, which showed the highest transcript level when subjected to 10 μM CuCl(2) and NiCl(2). Thus it may suggest that in P. ginseng heavy metal interaction on cell membrane induced expression of various defense related genes via jasmonic acid pathway and also possesses cross talk networks with other defense related pathways.

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 .…”

Cellular stress response mechanisms as therapeutic targets of ginsenosides

“…The content of ginsenosides was higher in the storage roots of American ginseng plants in draughty condition compared with controls well supplied with water, implying that drought stress may induce the synthesis of ginsenosides . Various ginsenoside biosynthetic pathway‐related genes (e.g., PgSQE , PgDDS , and Pgβ‐AS ) were highly responsive to heavy metal stress in Panax ginseng …”

“…32 Various ginsenoside biosynthetic pathwayrelated genes (e.g., PgSQE, PgDDS, and Pg -AS) were highly responsive to heavy metal stress in Panax ginseng. 33 Ginsenosides have been found to play a crucial defense role against biotic factors, such as insects and microorganisms. It has been observed that pests rarely feed on the stems and leaves of wild ginseng, which is highly associated with the content of ginsenosides.…”

“…Among them, Rg1 gained attention due to its four trans-ring rigid steroid skeleton similar to steroid hormones and amphiphilic nature. 6 A previous study demonstrated that Rg1 is a functional ligand of GR with a K d value of 1-10 M. 94 Recent studies demonstrated that Rg1 exhibited the function of promoting GR entry into the nucleus, while it inhibited NF-B pathway in LPS-induced RAW264.7 cells, 57 primary cultured cortical neurons after A [25][26][27][28][29][30][31][32][33][34][35] exposure, 53 and a mouse model of alcoholic hepatic injury. 95 Moreover, Rg1 interfered with the nuclear translocation of NF-B p65 in a GR or ER -dependent manner.…”

“…194 However, HIF-1 expression is downregulated by Rg3 in several cancer cell lines, including human ovarian cancer cells (e.g., SKOV3 and 3AO, 195 bone marrow stromal cells isolated from acute leukemia patients, 196 and human esophageal carcinoma cells [i.e., EC109, TE1, and KYSE170]) 197 and two tumor mice models, including Lewis lung cancer cell xenografted mice 198 and SKOV3 cells xenografted into nude mice. 195 Rg1 was also shown to decrease HIF-1 levels in A [25][26][27][28][29][30][31][32][33][34][35] -injured human endothelial EA.hy926 cells. 199 Vascular endothelial growth factor (VEGF) as the main downstream gene of HIF-1 was found to be upregulated by Rg1 192,193 and downregulated by Rg3.…”