Different Age-Induced Changes in Rhizosphere Microbial Composition and Function of Panax ginseng in Transplantation Mode

Transplantation is a cultivation mode widely applied in perennial plant growing. This method might be an effective way to alleviate problems associated with continuous cultivation (4-6 years) in ginseng production, but the alleviating mechanism and effects on soil microbial community is unclear. To study this issue, non-transplanted 2-year-old, and 5-year-old (transplantation mode: 2 + 3) and 9-year-old (transplantation mode: 3 + 3 + 3) ginseng rhizosphere soils were analyzed via MiSeq sequencing. The results showed that 9-year-old ginseng rhizosphere soil had lower available nitrogen and the lowest pH, available phosphorus, observed species and community diversity and richness (Chao1, and ACE) among all samples (p < 0.05). The abundances of some bacterial classes (Thermoleophilia, Bacilli, and Nitrospira) and fungal genera (Mortierella, Epicoccum, and Penicillium spp.) and functional richness associated with nutrient element cycles and antifungal activity decreased, while abundances of some fungal genera (Ilyonectria, Tetracladium, and Leptodontidium spp.) increased with increasing age of ginseng plants (p < 0.05 or p < 0.01). However, there was greater similarity between soil samples of 2-year-old and transplanted 5-year-old ginseng plants and the increase in cultivation time from 2 to 5 years did not significantly influence the microbial community, suggesting that transplantation is a viable strategy for suppressing soil-borne diseases in Panax ginseng plants over long growth periods.

Comparative phenolic compound profiles and antioxidative activity of the fruit, leaves, and roots of Korean ginseng (Panax ginseng Meyer) according to cultivation years

Background

The study of phenolic compounds profiles and antioxidative activity in ginseng fruit, leaves, and roots with respect to cultivation years, and has been little reported to date. Hence, this study examined the phenolic compounds profiles and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free-radical-scavenging activities in the fruit, leaves, and roots of Korean ginseng (Panax ginseng Meyer) as a function of cultivation year.

Methods

Profiling of 23 phenolic compounds in ginseng fruit, leaves, and roots was investigated using ultra-high performance liquid chromatography with the external calibration method. Antioxidative activity of ginseng fruit, leaves, and roots were evaluated using the method of DPPH free-radical-scavenging activity.

Results

The total phenol content in ginseng fruit and leaves was higher than in ginseng roots (p < 0.05), and the phenol content in the ginseng samples was significantly correlated to the DPPH free-radical-scavenging activity (r = 0.928****). In particular, p-coumaric acid (r = 0.847****) and ferulic acid (r = 0.742****) greatly affected the DPPH activity. Among the 23 phenolic compounds studied, phenolic acids were more abundant in ginseng fruit, leaves, and roots than the flavonoids and other compounds (p < 0.05). In particular, chlorogenic acid, gentisic acid, p- and m-coumaric acid, and rutin were the major phenolic compounds in 3–6-yr-old ginseng fruit, leaves, and roots.

Conclusion

This study provides basic information about the antioxidative activity and phenolic compounds profiles in fruit, leaves, and roots of Korean ginseng with cultivation years. This information is potentially useful to ginseng growers and industries involved in the production of high-quality and nutritional ginseng products.