Deciphering the key soil microbial taxa that contribute to saponin accumulation in a geo-authentic Sanqi ginseng production area: Evidence from four different varieties

Abstract

Sanqi ginseng (Panax notoginseng) is a typical geo-authentic medicinal herb and the accumulation of saponins heavily relies on its growing environment. However, the effects of soil factors on saponin accumulation are still not well characterized. In this study, four different varieties (improved varieties: KZ, HD and PK; common variety: PT) and two typical soils (geo-authentic soil: QB; non-geo-authentic soil: SL) were selected for pot experiments, and the root biomass and saponin content, as well as the soil microbiome were investigated after one-year of cultivation. Results showed that soil, rather than variety, was the determinant of the root development and saponin accumulation of Sanqi ginseng. Sanqi ginseng cultivated in the QB soil had better root morphology (with long and dense fibrous roots) and higher saponin accumulation. Compared to the physicochemical properties, the soil microbiome exhibited a higher explanatory power (24.68 %) for the biomass and saponin of Sanqi ginseng, and its α-diversity and β-diversity were strongly related to biomass, saponin content and saponin accumulation. Random forest regression analysis further revealed that those having high and positive contributions to biomass and saponin accumulation, such as bacterial genera Arthrobacter, Gaiella, Granulicella, Bradyrhizobium, Rhizomicrobium, Rhizobium and Streptomyces, and fungal genera Fusarium, Plenodomus, Setophoma and Trichoderma, were significantly enriched in QB soil. This study revealed that soil is one of the key factors for producing geo-authentic Sanqi ginseng and highlighted the importance of key soil microbial taxa in the saponin accumulation of Sanqi ginseng, thus providing a theoretical basis for quality improvement through microbiome regulation.