Complexity Reduction and Sustaining Plant Growth Promotion in a Beneficial Sorghum SynCom

The inherent complexity and functional redundancy of natural plant microbiomes present a formidable barrier to elucidating the manifold biological interactions. Synthetic microbial communities (SynComs) offer a tractable experimental system to decouple these complex interactions. Beyond their usefulness as tools for basic science, SynComs may be used as tools for crop improvement. This study outlines a top-down strategy to simplify a beneficial, SynCom, originally derived from Sorghum, while preserving significant plant growth promotion. We assessed colonization and plant growth promotion of four different community compositions representing diverse complexity reduction strategies. This process resulted in a significantly simplified community, SRC2v4, which retains substantial, though reduced, plant growth promotion efficacy compared to the original consortium. The resulting reduced consortium is highly stable, soil-independent, and provides a proof-of-concept for the rational design of microbial products. Characterization of longitudinal plant transcriptional responses to SRC2v4 revealed a spatiotemporal dynamic transduction of SynCom perception defined by flavonoid production and regulation of hormone modulation machinery. Our findings offer a framework for the development of next-generation microbial products for sustainable agriculture.