Metabolic dynamics and physiological adaptation of Panax ginseng during development.

KEY MESSAGE: The dynamics of metabolites from leaves to roots of Panax ginseng during development has revealed the tissue-specific and year-specific metabolic networks. Being an essential Oriental medicinal plant, ginseng (Panax ginseng Meyer) is a slow-growing perennial herb-accumulating pharmaceutically active metabolites such as ginsenosides in roots during growth. However, little is known about how ginseng plants survive in the harsh environments such as winter cold and summer heat for a longer period and accumulates those active metabolites as the plant grows. To understand the metabolic kinetics in both source and sink organs such as leaves and roots of ginseng plant, respectively, and to assess the changes in ginsenosides biosynthesis during ginseng growth, we investigated the metabolic profiles from leaves and roots of 1-, 4-, and 6-year-old field-grown ginseng plants. Using an integrated non-targeted metabolomic approach, we identified in total 348 primary and secondary metabolites, which provided us for the first time a global metabolomic assessment of ginseng during growth, and morphogenesis. Strikingly, the osmoprotectants and oxidized chemicals were highly accumulated in 4- and 6-year-old ginseng leaves suggested that ginseng develop a wide range of metabolic strategies to adapt unfavorable conditions as they mature. In 6-year-old plants, ginsenosides were decreased in leaves but increased in roots up to 1.2- to sixfold, supporting the view that there is a long-distance transport of ginsenosides from leaves to roots as ginseng plants mature. Our findings provide insights into the metabolic kinetics during the development of ginseng plant and this could complement the pharmacological importance of ginseng and its compounds according to their age.

Phycicoccus ginsengisoli sp. nov., isolated from cultivated ginseng soil.

Ginseng-cultivated soil is an excellent habitat for soil-borne bacteria to proliferate. A novel strain, DCY87T, was isolated from ginseng-cultivated soil in Gochang County, Republic of Korea, and subsequently characterized by polyphasic approach. Cells were rod shaped, non-motile, aerobic, Gram-reaction-positive, oxidase-negative and catalase-positive. 16S rRNA gene sequence analysis showed that strain DCY87T shared the highest similarity to 'Phycicoccus ochangensis' L1b-b9 (98.7 %). Closely phylogenetic relatives of strain DCY87T were identified: Phycicoccus ginsenosidimutans BXN5-13T (97.9 %), Phycicoccus soli THG-a14T (97.8 %), Phycicoccus bigeumensis MSL-03T (97.3 %), Phycicoccus cremeus V2M29T (97.3 %), Phycicoccus aerophilus 5516T-20T (97.3 %), Phycicoccus dokdonensis DS-8T (97.3 %) and Phycicoccus jejuensis KSW2-15T (97.1 %). The major polar lipids were classified as phosphatidylinositol and diphosphatidylglycerol. The major cellular fatty acids were composed of iso-C15 : 0, anteiso-C15:0, C17 : 0 and C17 : 1ω8c. The menaquinone was resolved as MK-8(H4). Strain DCY87T contained meso-diaminopimelic acid as diamino acid in the cell-wall peptidoglycan and glucose, xylose and rhamnose in the whole-cell sugar. The genomic DNA G+C content was calculated to be 72.7 mol%. DNA-DNA hybridization value between strain DCY87T and 'P. ochangensis' L1b-b9 was estimated to be 50 %. However, DNA-DNA hybridization value obtained between strain DCY87T and P. ginsenosidimutans BXN5-13T, P. soli THG-a14T and P. bigeumensis MSL-03T was well below 17 %. In general, polyphasic taxonomy demonstrated that DCY87T strain represented a novel species within the genus Phycicoccus. Accordingly, we propose the name Phycicoccus ginsengisoli sp. nov. The type strain is DCY87T (=KCTC 39635T=JCM 31016T).

Development of interspecies hybrids to increase ginseng biomass and ginsenoside yield.

KEY MESSAGE: Interspecific hybrids between Panax ginseng and P. quinquefolius results in hybrid vigor and higher ginsenoside contents. Ginseng is one of the most important herbs with valued pharmaceutical effects contributing mainly by the presence of bioactive ginsenosides in the roots. However, ginseng industry is impeded largely by its biological properties, because ginseng plants are slow-growing perennial herbs with lower yield. To increase the ginseng yield and amounts of ginsenosides, we developed an effective ginseng production system using the F(1) progenies obtained from the interspecific reciprocal cross between two Panax species: P. ginseng and P. quinquefolius. Although hybrid plants show reduced male fertility, F(1) hybrids with the maternal origin either from P. ginseng or P. quinquefolius displayed heterosis; they had larger roots and higher contents of ginsenosides as compared with non-hybrid parental lines. Remarkably, the F(1) hybrids with the maternal origin of P. quinquefolius had much higher ginsenoside contents, especially ginsenoside Re and Rb1, than those with the maternal origin of P. ginseng. Additionally, non-targeted metabolomic profiling revealed a clear increase of a large number of primary and secondary metabolites including fatty acids, amino acids and ginsenosides in hybrid plants. To effectively identify the F(1) hybrids for the large-scale cultivation, we successfully developed a molecular marker detection system for discriminating F(1) reciprocal hybrids. In summary, this work provided a practical system for reciprocal hybrid ginseng production, which would facilitate the ginseng production in the future.

Investigation of ginsenosides in different tissues after elicitor treatment in Panax ginseng.

BACKGROUND: The effect of methyl jasmonate (MJ) on ginsenoside production in different organs of ginseng (Panax ginseng Meyer) was evaluated after the whole plant was dipped in an MJ-containing solution. MJ can induce the production of antioxidant defense genes and secondary metabolites in plants. In ginseng, MJ treatment in adventitious root resulted in the increase of dammarenediol synthase expression but a decrease of cycloartenol synthase expression, thereby enhancing ginsenoside biosynthesis. Although a previous study focused on the application of MJ to affect ginsenoside production in adventitious roots, we conducted our research on entire plants by evaluating the effect of exogenous MJ on ginsenoside production with the aim of obtaining new approaches to study ginsenoside biosynthesis response to MJ in vivo. METHODS: Different parts of MJ-treated ginseng plants were analyzed for ginsenoside contents (fine root, root body, epidermis, rhizome, stem, and leaf) by high-performance liquid chromatography. RESULTS: The total ginsenoside content of the ginseng root significantly increased after 2 d of MJ treatment compared with the control not subjected to MJ. Our results revealed that MJ treatment enhances ginsenoside production not in the epidermis but in the stele of the ginseng root, implying transportation of ginsenosides from the root vasculature to the epidermis. Application of MJ enhanced protopanaxadiol (PPD)-type ginsenosides, whereas chilling treatment induced protopanaxatriol (PPT)-type ginsenosides. CONCLUSION: These findings indicate that the production of PPD-type and PPT-type ginsenosides is differently affected by abiotic and biotic stresses in the ginseng plant, and they might play different defense mechanism roles.