Abstract:

The establishment of plant-beneficial bacterial inoculants in the rhizosphere remains inconsistent under field conditions, largely due to competition with resident microorganisms. Heritable, seed-borne bacteria arrive first to this niche and likely drive early rhizosphere microbiome assembly through priority effects. However, the metabolic interactions between seed and soil bacteria remain largely unexplored and could greatly impact new strategies for enhancing the establishment of plant-beneficial inoculants. We constructed genome-scale metabolic models for approximately 40 bacterial isolates obtained from wheat seeds, the wheat rhizosphere, and soil, to identify potential competition, niche partitioning, and facilitative metabolic interactions among early- and late-arriving bacteria. We are experimentally validating carbon utilization profiles and constructing different synthetic communities (SynComs) to study how seed-borne bacteria influence community assembly. By manipulating the arrival order of seed bacteria and performing drop-out experiments, we aim to determine whether seed bacteria act as major drivers of wheat rhizosphere microbiome assembly through priority effects. This framework will also allow us to test how plant-beneficial inoculants establish within communities shaped by inherited bacteria, providing ecological principles to improve inoculant integration into the rhizosphere microbiome.