The genotypically conserved core microbiota modulates nutrient turnover in soybean rhizosphere.

Microbiota-mediated nutrient turnover in the rhizosphere determines nutrient bioavailability, thereby enhancing nutrient uptake, utilization, and ultimately crop productivity. Consequently, elucidating the functional core microbiota in rhizosphere nutrient turnover is of critical importance. In this study, we leveraged soybean germplasm core collections to investigate the tripartite relationship among host genotype, core microbiota and nutrient availability, with a focus on delineating the pivotal role of core microbiota in nutrient turnover. Our results suggest that phylogenetic variation significantly shape root-associated microbial communities and rhizosphere nutrient availability, explaining 11.75 % and 2.07 % of total variances, respectively. Core microbiota analysis identified 29 phylogenetic conserved core amplicon sequence variants (ASVs), the majority of which exhibited significant correlated with nutrient availability. Notably, three key core ASVs-ASV13, ASV14 and ASV12, positively correlated with alkali-hydrolyzed nitrogen, available phosphorus, and soil organic matter, respectively. These taxa were subsequently incorporated into a Bradyrhizobium-based synthetic bacterial community (SynCom) to validate their functional roles. Further experiments confirmed that core microbiota-driven nutrient turnover directly facilitates host plant, as evidenced by SynCom inoculation assays. Collectively, this study establishes that phylogenetically conserved core microbiota critically regulate nutrient turnover and acquisition efficiency in the rhizosphere. These insights advance our understanding the ecological function of core microbiota in the rhizosphere and provide a framework for harnessing the beneficial traits in sustainable agriculture.