Plant Triterpenoids Regulate Endophyte Community to Promote Medicinal Plant Schisandra sphenanthera Growth and Metabolites Accumulation.

Chuan You,Baohong Yu,Jieru Xu,Wenyi Lan,Yumeng Wang,Yehong Li,Jinyan Dong,Yajun Peng,Dan Qin

doi:10.3390/jof7100788

Abstract

Beneficial interactions between endophytes and plants are critical for plant growth and metabolite accumulation. Nevertheless, the secondary metabolites controlling the feedback between the host plant and the endophytic microbial community remain elusive in medicinal plants. In this report, we demonstrate that plant-derived triterpenoids predominantly promote the growth of endophytic bacteria and fungi, which in turn promote host plant growth and secondary metabolite productions. From culturable bacterial and fungal microbial strains isolated from the medicinal plant Schisandra sphenanthera, through triterpenoid-mediated screens, we constructed six synthetic communities (SynComs). By using a binary interaction method in plates, we revealed that triterpenoid-promoted bacterial and fungal strains (TPB and TPF) played more positive roles in the microbial community. The functional screening of representative strains suggested that TPB and TPF provide more beneficial abilities to the host. Moreover, pot experiments in a sterilized system further demonstrated that TPB and TPF play important roles in host growth and metabolite accumulation. In summary, these experiments revealed a role of triterpenoids in endophytic microbiome assembly and indicated a strategy for constructing SynComs on the basis of the screening of secondary metabolites, in which bacteria and fungi join forces to promote plant health. These findings may open new avenues towards the breeding of high yielding and high metabolite-accumulating medicinal plants by exploiting their interaction with beneficial endophytes.

Highlights

Endophytes colonize the tissue or intercellular spaces of various plant organs, live in healthy plants, at least at a certain stage or even during the whole life cycle, and do not cause obvious plant diseases [1]
We isolated endophytic bacteria and fungi from the plant organs of S. sphenanthera, which were assayed by the purified triterpenoids and filtered to construct synthetic communities (SynComs) on the basis of triterpenoid screening
Our work suggests that triterpenoids, other than their wide biological activity, may play a role in the assembly and stabilization of the plant’s endophytic microbiome

Summary

Introduction

Endophytes (fungi and bacteria) colonize the tissue or intercellular spaces of various plant organs, live in healthy plants, at least at a certain stage or even during the whole life cycle, and do not cause obvious plant diseases [1]. The endophytic microbiome plays an important role in different functions such as plant growth, development, signal network, gene expression, metabolic pathways and response to biological stress [2,3,4]. Plants actively recruit and nurture a collection of microbes from the soil to live in the vicinity, on the surface and inside their tissues [1]. Endophytic microbes provide various essential nutrients (i.e., nitrogen and phosphorous) to the host species, which promote plant growth and increase environmental tolerance and phytopathogenic resistance. The plant partners offer stable niches and photosynthetic productions to the endophytes [6]. Few studies have reported on the secondary metabolites that influence the assemblies of the endophytic microbiome in plants

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Discussion

Conclusion