Microbial communities of Schisandra sphenanthera Rehd. et Wils. and the correlations between microbial community and the active secondary metabolites

Abstract

Background: Schisandra sphenanthera Rehd. et Wils. is a plant used in traditional Chinese medicine (TCM). However, great differences exist in the content of active secondary metabolites in various parts of S. sphenanthera. Do microorganisms critically influence the accumulation of active components in different parts of S. sphenanthera?

Methods: In this study, 16S/ITS amplicon sequencing analysis was applied to unravel microbial communities in rhizospheric soil and different parts of wild S. sphenanthera. At the same time, the active secondary metabolites in different parts were detected, and the correlation between the secondary metabolites and microorganisms was analyzed.

Results: The major components identified in the essential oils were sesquiterpene and oxygenated sesquiterpenes. The contents of essential oil components in fruit were much higher than that in stem and leaf, and the dominant essential oil components were different in these parts. The dominant components of the three parts were γ-muurolene, δ-cadinol, and trans farnesol (stem); α-cadinol and neoisolongifolene-8-ol (leaf); isosapathulenol, α-santalol, cedrenol, and longiverbenone (fruit). The microbial amplicon sequences were taxonomically grouped into eight (bacteria) and seven (fungi) different phyla. Community diversity and composition analyses showed that different parts of S. sphenanthera had similar and unique microbial communities, and functional prediction analysis showed that the main functions of microorganisms were related to metabolism. Moreover, the accumulation of secondary metabolites in S. sphenanthera was closely related to the microbial community composition, especially bacteria. In endophytic bacteria, Staphylococcus and Hypomicrobium had negative effects on five secondary metabolites, among which γ-muurolene and trans farnesol were the dominant components in the stem. That is, the dominant components in stems were greatly affected by microorganisms. Our results provided a new opportunity to further understand the effects of microorganisms on the active secondary metabolites and provided a basis for further research on the sustainable utilization of S. sphenanthera.

Keywords: Active secondary metabolites; Endophytes; Plant microbiome; Rhizospheric soil microorganism; Schisandra sphenanthera Rehd. et Wils..

Figure 1. Stack diagram at the level of the phylum of the sample.

(A) Bacteria. (B) Fungi. Rh.soil, Rhizosphere soil.

Figure 2. The differences in the abundance of the common genus of microbial in rhizosphere soil and different parts of S. sphenanthera (m ± sd).

(A) Bacteria. (B) Fungal. Different lowercase letters (a–c) indicate significant differences (p < 0.05) of the same genera between rhizosphere soil and different parts of S. sphenanthera, one-way ANOVA, Tukey test.

Figure 3. Horizontal clustering tree-stacking diagram of microbial function annotation (A: bacteria, B: fungal) and trophic mode of fungal (c) in rhizosphere soil and different parts of S. sphenanthera.

RF, Rhizosphere soil; R, Root; S, Stem; L, Leaf; and F, Fruit.

Figure 4. Common chemical compositions (sesquiterpenes and oxygenated sesquiterpenes) identified in the volatile oils of different parts of S. sphenanthera.

Figure 5. Pearson correlations between genera of microbial and common chemical compositions of S. sphenanthera.

Asterisks (*, **, ***) indicate significant correlation estimates at the level of 0.05, 0.01, and 0.001, respectively.