Synthetic bacterial community colonizes wheat roots grown in soil and mimics the assembly pattern of a field community in a cultivar dependent manner

TL;DR

A synthetic bacterial community was developed to mimic the natural wheat root microbiome, showing similar growth and assembly patterns in one wheat variety but not another.

Contribution

A SynCom was created that mimics field microbiome assembly in a cultivar-specific manner when inoculated into soil.

Findings

The SynCom grew comparably to a natural community in winter wheat over 4 weeks.

Most SynCom strains mirrored the abundance dynamics of their genera in field-grown wheat of the same cultivar.

The SynCom's effects were not observed in a different wheat cultivar, highlighting plant genotype specificity.

Abstract

The root microbiome is important for plant development. The impact of the root microbiome is the result of multiple complex interactions among microorganisms, the plant and the environment. This complexity can be reduced by designing synthetic bacterial communities (SynComs) consisting of bacteria isolated from the roots, making it possible to study these interactions. However, the translational power from SynCom experiments to explain field observations is still very low, which demonstrates the need for development of SynComs that colonize plants comparable to what is observed in the field. Hence, we developed a SynCom consisting of 13 different strains from 13 genera with varying phenotypes originating from the roots of winter wheat (Triticum aestivum cv. Sheriff). The SynCom was inoculated into gamma-irradiated soil prior to sowing and community assembly was determined over 4 weeks using 16S rRNA amplicon sequencing. Winter wheat plants inoculated with the developed SynCom grew comparably to plants inoculated with a natural community (NatCom) obtained from a soil solution over the 4-week period. Furthermore, the temporal dynamics of the majority of the SynCom strains mimicked the development in relative abundance of their respective genera in field grown winter wheat of the same cultivar. However, this could not be translated to a different cultivar (Heerup). Our results demonstrate how SynComs inoculated into gamma-irradiated soil can provide a promising framework to study root microbiome assembly and relate the findings to field observations. At the same time, it highlights the plant-genotype specific impact on community assembly.

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