To compare differences in metabolic profiles of wild and cultivated Panax ginseng by habitat, I conducted metabolite analysis using high performance liquid chromatography-diode array detector mass spectrometry (HPLC-DAD-MS) and gas chromatography-mass spectrometry (GC-MS) in addition to terminal restriction fragment length polymorphism (T-RFLP) analysis for soil rhizosphere bacterial community. Ginsnengs and rhizosphere soils were collected in summer and autumn 2015 and spring 2016 at three sites: a wild Panax ginseng habitats (WH) located in a mountain area, Seosan-si and two Panax ginseng cultivating habitats (CH1 and CH2) located in Nonsan-si and in Imsil-gun, respectively. Principal component analysis (PCA) results showed differences in metabolic profiles between leaves and roots for cultivated ginsengs. The PCA scores based on GC-MS profiles of P. ginseng root samples (epidermis part and cortex part) showed seasonal differences between summer and autumn. PCA results using epidermis and cortex showed that wild ginseng had different metabolic profiles from cultivated ones. The PCA scores also showed clear differences among habitats in soil rhizosphere bacterial community compositions on ginseng roots. PCA scores revealed that metabolic profiles of ginseng epidermis showed more similar patterns than cortex when compared with PCA results on rhizosphere bacterial communities. These results might indicate that epidermis could play a role as a bridge between plant root and soil.
To examine interactions between ginseng roots and soil bacterial communities further, a growth experiment was conducted using soils from the studied sites in a growth chamber for 12 weeks. The PCA results showed that metabolic profiles of root epidermis were not different among different soils (WH, CH1 and CH2). On the contrary, the PCA results on metabolic profiles of root epidermis with sterilized soils (SWH, SCH1 and SCH2) showed clear differences. The PCA results on soil rhizosphere bacterial communities showed similar patterns. In terms of ginsenoside content, ratios of ginsenoside protopanaxadiol group (PPD) to ginsenoside protopanaxatriol group (PPT) was different between ginsengs grown unsterilized and ones grown sterilized soils. Ratios of PPD of ginseng grown in unsterilized soils (WH, CH1 and CH2) was higher than ratios of PPD of ones grown sterilized soils (SWH, SCH1 and SCH2). These differences for ginseng metabolites between unsterilized and sterilized soils suggest that ginseng metabolomes interact with soil rhizosphere bacterial communities.