Rice domestication influences the composition and function of the rhizosphere bacterial chemotaxis systems

Aims: Specific soil bacteria can sense and respond to the selective rhizosphere recruitment of root exudates using unique systems of chemotaxis that mediate plant-microbe and microbe-microbe interactions. This study investigates how the bacterial chemotaxis systems have been impacted by selection during the domestication of rice (Oryza species). Methods: Shotgun metagenomic sequencing and 16S rRNA gene amplicon sequencing were performed to investigate the bacterial chemotaxis systems and chemotactic bacteria in the rhizospheres of wild and cultivated rice. Metabolomics analysis was performed to examine the root metabolites of different accessions of rice. Results: The bacterial chemotaxis genes exhibited a higher abundance in the rhizospheres of wild rice than cultivated rice, and that the compositional profile of chemotaxis genes was distinctly different between types of rice. Differential selection of chemotaxis systems was at least partially driven by changes in the metabolite profiles of rice roots that were affected by domestication. A core group of chemotactic bacteria was also identified, and specific chemotactic bacteria were found to function as hub taxa in the rhizosphere bacterial community. Conclusion: The present study provides novel insights into the composition and function of the bacterial chemotaxis systems in the rhizospheres of wild and domesticated rice. It also provides a new perspective on the impact of rice domestication on the assembly of rhizomicrobiome.