Functional predictions of bacterial communities associated with sorghum cultivars across different rhizocompartments

Abstract

The plant root microbiome played critical roles in nutrient acquisition and stress resilience, yet the impacts of host genotype on microbial functions remained poorly understood, particularly in economically important crops like sorghum. This study investigated how three genetically distinct sorghum cultivars ( Hongyingzi , Hongzhenzhu , and Jinza ) shaped microbial functional profiles across rhizocompartments (rhizosphere, rhizoplane, endosphere) and their contributions to soil nutrient dynamics. Using 16S rRNA sequencing combined with predictive functional profiling (PICRUSt2, FAPROTAX) and soil physicochemical analyses, we revealed compartment-specific functional stratification driven by cultivars. Results demonstrated pronounced genotype-dependent microbial functional adaptation: Jinza exhibited enhanced biofilm formation and aromatic compound utilization in the endosphere, while Hongyingzi prioritized broad metabolic versatility in the rhizoplane. Pathway enrichment analyses highlighted cultivar-specific strategies, with Hongzhenzhu showing heightened sulfur metabolism and nitrogen fixation in the rhizoplane, and Jinza displaying specialized nutrient transport pathways in the endosphere. Correlation networks further linked dominant taxa (e.g., Burkholderiales, Rhizobiales) to key metabolic processes, including pollutant degradation and stress response. Random forest models revealed increasing functional specialization from rhizosphere to endosphere, with microbial activities explaining 30% of total organic carbon variation and 28.7% of nitrogen availability in the endosphere. This compartmental gradient underscored host-mediated selection for microbial functions critical to nutrient cycling and plant performance. By disentangling genotype-driven functional adaptations in root microbiomes, this study advanced understanding of plant-microbe interactions beyond taxonomic composition, providing a framework for engineering microbiomes to enhance crop sustainability in diverse agroecosystems.

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