Dynamic response of ginsenosides in American ginseng to root fungal pathogens

Abstract

The existence of a complex relationship between soil microbes and ginsenoside contents in their host plants has been reported by previous studies. Here, we analyzed the interaction between the root pathogens and the ginsenoside content in the roots of American ginseng. Two fungal pathogen species were isolated from diseased American ginseng roots, and identified as Fusarium oxysporum (isolate C1) and Fusarium solani (isolate F19) by molecular sequencing analysis. To determine the effect of Fusarium-mediated infection of American ginseng roots, the contents of three ginsenosides, ginsenosides Rb 1 , ginsenosides Re and ginsenosides Rg 1 , were monitored over a time course of 120 h post infection using high performance liquid chromatography (HPLC). We found that the level of Rb 1 was rapidly upregulated upon fungal infection, whereas the contents of Re or Rg 1 were not altered significantly. Furthermore, the presence of Rb 1 , but not Re or Rg 1 , significantly inhibited conidium germination of both Fusarium species. Thus, Rb 1 is likely the disease-resistance compound produced by American ginseng roots in response to the pathogenic fungi. Our study is the first to report the three ginsenosides with different chemical structure respond differently to soilborne pathogen infection.

Ginsenosides in root exudates of Panax notoginseng drive the change of soil microbiota through carbon source different utilization

“…Ginsenosides, the main bioactive ingredients of Panax plants, can be secreted into the rhizosphere soil by roots, exerting autotoxicity or promoting the growth of root pathogens (Jiao et al 2010;Lei et al 2010;Nicol et al 2003;Yang et al 2015). Here, we found that both exogenous root exudates of P. notoginseng and a mixture of Rg 1 , Rb 1 and Rd ginsenosides at the corresponding concentrations found in root exudates could drive a similar change in soil microbiota.…”

“…Many studies have shown that triterpenoid saponins can act as phytoalexins by providing a chemical defense against fungal infections in oats and tomatoes (Turner 1956;Osbourn 1996). Like other saponins, ginsenosides can also serve as chemical defenses against the infection of pathogen at high concentrations (Jiao et al 2010). Moreover, ginsenosides could inhibit the growth of Trichoderma hamatum (Nicol et al 2003) and other non-host pathogens (Yang et al 2018b).…”

Autotoxic Ginsenosides in the Rhizosphere Contribute to the Replant Failure of Panax notoginseng

“…Ginsenosides are primary components of ginseng and play a multi-purpose ecological role. Like other saponins, ginsenosides are fungitoxic in plants and act as a host for chemical defenses at high concentrations [ 43 ]. In the rhizosphere, ginsenosides not only exert autotoxic effects on Sanqi ginseng plants, resulting in poor defense and growth, but also stimulate the growth of soil-borne pathogens.…”

Cellular stress response mechanisms as therapeutic targets of ginsenosides

“…The crude ginseng saponin fraction isolated from American ginseng exhibited antifungal activity and ginsenosides isolated from African Combretaceae exerted antimicrobial activity . Rb1, but not Re or Rg1, rapidly accumulated in the roots of American ginseng upon infection with two fungi, Fusarium oxysporum and Fusarium solani , and effectively inhibited conidium germination of both Fusarium species; this implies that Rb1 functions as a chemical defense mechanism in American ginseng roots against pathogenic fungi …”

“…39 Rb1, but not Re or Rg1, rapidly accumulated in the roots of American ginseng upon infection with two fungi, Fusarium oxysporum and Fusarium solani, and effectively inhibited conidium germination of both Fusarium species; this implies that Rb1 functions as a chemical defense mechanism in American ginseng roots against pathogenic fungi. 40 Ginsenosides may also interrupt the life cycle of insects by binding to the ecdysteroid receptor due to the structural similarities between ginsenosides and ecdysteroids, which are the insect molting and metamorphosis hormones. 41,42…”