GC-MS Metabolomic Analysis to Reveal the Metabolites and Biological Pathways Involved in the Developmental Stages and Tissue Response of Panax ginseng.

Jia Liu,Ann Abozeid,Yang Liu,Yu Wang,Zhong-Hua Tang,Xiao-Ning Zhang,Yuan-Gang Zu

doi:10.3390/molecules22030496

Abstract

Ginsenosides, the major compounds present in ginseng, are known to have numerous physiological and pharmacological effects. The physiological processes, enzymes and genes involved in ginsenoside synthesis in P. ginseng have been well characterized. However, relatively little information is known about the dynamic metabolic changes that occur during ginsenoside accumulation in ginseng. To explore this topic, we isolated metabolites from different tissues at different growth stages, and identified and characterized them by using gas chromatography coupled with mass spectrometry (GC-MS). The results showed that a total of 30, 16, 20, 36 and 31 metabolites were identified and involved in different developmental stages in leaf, stem, petiole, lateral root and main root, respectively. To investigate the contribution of tissue to the biosynthesis of ginsenosides, we examined the metabolic changes of leaf, stem, petiole, lateral root and main root during five development stages: 1-, 2-, 3-, 4- and 5-years. The score plots of partial least squares-discriminate analysis (PLS-DA) showed clear discrimination between growth stages and tissue samples. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis in the same tissue at different growth stages indicated profound biochemical changes in several pathways, including carbohydrate metabolism and pentose phosphate metabolism, in addition, the tissues displayed significant variations in amino acid metabolism, sugar metabolism and energy metabolism. These results should facilitate further dissection of the metabolic flux regulation of ginsenoside accumulation in different developmental stages or different tissues of ginseng.

Highlights

The metabolic network in plants is by far more extensive than those found in most other organisms.Apart from producing primary metabolites (PMs) plants synthesize a vast range of secondary metabolites (SMs) [1]
Rd, Rb1, Rb2, Rf, Rh, Rh2, Rc (Table this study the total content including of these ten in different tissues during different developmental stages showed the total content of these ten ginsenosides in different tissues during different developmental (Figure 1)
There was a sharp increase in petiole content during the first three years, followed by a gradually decrease during the fourth and fifth year. These results indicated that the correlation between the developmental stage and ginsenoside content in the same tissue is complex, and may be regulated by the synthesis of other metabolites

Summary

Introduction

The metabolic network in plants is by far more extensive than those found in most other organisms.Apart from producing primary metabolites (PMs) plants synthesize a vast range of secondary (or specialized) metabolites (SMs) [1]. The major SM classes produced by plants can be divided into three main groups: phenolic compounds, terpenoids/isopreoids, and nitrogen. The tight link between metabolic fluxes of PMs and the accumulation of SMs renders the engineering of the latter compounds quite complex as it demands the consideration of the entire metabolic network in order to redirect PM resources into SMs without interfering with plant fitness [6,7]. For example the content of metabolically linked carbon and nitrogen compounds, has a major quantitative impact on the extent of production of SMs in plants [8,9]. Taking all of the above into consideration, metabolic engineering to stimulate the levels of these active molecules in plants is nowadays a major challenge for plant biotechnology

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Discussion

Conclusion