Dynamic shifts in rhizosphere bacterial microbiota mediated by soil nutrient limitations across developmental stages in potato

Soil fertility critically influences plant growth and development and governs the dynamic shifts of rhizosphere microbial communities. To clarify the influence of soil fertility on the microbial aggregation in the rhizosphere of potatoes, we predicted the composition and functional changes of the rhizosphere microbial community by high-throughput sequencing of 16S rRNA in potato rhizosphere samples at different fertility levels and three growth stages. Here, we demonstrate that potato growth traits varied depending on soil fertility levels, with higher fertility improving plant growth and tuber yield. Amplicon sequencing of potato rhizosphere samples across different soil fertility levels and three growth stages revealed that α-diversity and β-diversity were primarily driven by soil fertility rather than plant developmental stage. The assembly process of rhizosphere microbial community was dominated by stochastic processes. Furthermore, increasing soil fertility enhanced the complexity of microbial interactions, as indicated by co-occurrence network analyses. We further identified Sphingobium , Mucilaginibacter , Sphingomonas , and Streptomyces as conserved biomarker genera distinguishing the three fertility treatments. Additionally, soil total organic carbon (TOC), total nitrogen (TN), available nitrogen (AN), and total phosphorus (TP) showed significant positive correlations with Mucilaginibacter abundance but negative correlations with Sphingobium . The growth promoting effects of Sphingobium on potato plants were also tested. These findings provide crucial insights into the regulatory mechanisms of soil fertility on plant–microbe interactions and offer a scientific basis for optimizing crop production and soil health through fertility management strategies.