Priority effects of heritable seed-borne bacteria drive early assembly of the wheat rhizosphere microbiome

Microbial communities play a critical role in supporting plant health and productivity, making the ability to obtain reproducible plant-associated microbiomes an essential asset for experimentally testing hypotheses related to microbiome manipulation and fundamental principles governing community dynamics. We used a sequential propagation strategy to generate a complex and reproducible wheat rhizosphere microbiome (RhizCom) that was shaped by host selection and periodic habitat resetting. Heritable seed-borne rhizosphere bacteria (SbRB) emerged as the dominant microbiome source after coalescing with the soil community, driven by priority effects and efficient niche exploitation during early habitat development. Functional analyses revealed that niche partitioning through the ability of SbRB to degrade specific saccharides and niche facilitation contributed to the assembly of the RhizCom. Our results advance our understanding of the principles governing microbial community dynamics in early plant development and provide strategies for future microbiome manipulation aimed at improving crop productivity and health.