PgMYB2, a MeJA-Responsive Transcription Factor, Positively Regulates the Dammarenediol Synthase Gene Expression in Panax Ginseng

Abstract

The MYB transcription factor family members have been reported to play different roles in plant growth regulation, defense response, and secondary metabolism. However, MYB gene expression has not been reported in Panax ginseng. In this study, we isolated a gene from ginseng adventitious root, PgMYB2, which encodes an R2R3-MYB protein. Subcellular localization revealed that PgMYB2 protein was exclusively detected in the nucleus of Allium cepa epidermis. The highest expression level of PgMYB2 was found in ginseng root and it was significantly induced by plant hormones methyl jasmonate (MeJA). Furthermore, the binding interaction between PgMYB2 protein and the promoter of dammarenediol synthase (DDS) was found in the yeast strain Y1H Gold. Moreover, the electrophoretic mobility shift assay (EMSA) identified the binding site of the interaction and the results of transiently overexpressing PgMYB2 in plants also illustrated that it may positively regulate the expression of PgDDS. Based on the key role of PgDDS gene in ginsenoside synthesis, it is reasonable to believe that this report will be helpful for the future studies on the MYB family in P. ginseng and ultimately improving the ginsenoside production through genetic and metabolic engineering.

MYB Transcription Factors as Regulators of Secondary Metabolism in Plants

“…Heterologous expression of Dendrobium officinale DoMYB75 in A. thaliana can significantly increase seed water-soluble polysaccharide content [20]. Panax Ginseng PgMYB2, a nucleus localization protein, may play a key regulatory role in ginsenoside synthesis [48].…”

Methyl jasmonate promote protostane triterpenes accumulation by up-regulating the expression of squalene epoxidases in Alisma orientale

“…The expression levels of WsMYC2 was enhanced and the contents of withanolides in the plants also increased significantly in Withania somnifera (L.) Dunal after MeJA treatment 54 . In P. ginseng , PgMYB2 could up-regulate the expression of dammarenediol synthase after MeJA treatment 55 . Moreover, the increase in membrane permeability by MeJA application can facilitate the combination of substrate and enzyme, and increase the rate of secondary metabolite synthesis 56 .…”

Ectopic Expression of Production of Anthocyanin Pigment 1 (PAP1) Improves the Antioxidant and Anti-Melanogenic Properties of Ginseng (Panax ginseng C.A. Meyer) Hairy Roots

“…Furthermore, PgMYB2 ( P. ginseng MYB2), a homolog of AtMYB6 ( Arabidopsis R2R3-MYB transcription factor), has been suggested to be a major factor for the enhancement of ginsenoside production via the induction of PgDDS transcription [ 43 ]. These results indicate that the production of ginsenosides is likely controlled by several transcription factors, and the reduction of some ginsenoside levels by PAP1-overexpression might be attributed to secondary metabolite imbalances.…”