Host Genotype Shapes Rhizosphere Microbiome Assembly and Function to Modulate Cadmium Translocation in Rice

Aims Cadmium (Cd) contamination in rice ( Oryza sativa L. ) threatens food safety and human health. Developing low-Cd-accumulating cultivars and understanding their interaction mechanisms with the environmental microbiome has become a key task for ensuring food security. This study explores the role of host genotype (plant variety) in shaping the rhizosphere microbiome and its functional implications for modulating Cd translocation. Methods We compared a high-Cd-accumulating control (CK, Tianyou) with two low-Cd cultivars, SX (Shaoxiang) and QL (Qinglian). Both SX and QL significantly reduced grain Cd content, primarily through restricting Cd translocation from roots to aerial tissues. Results Integrated metagenomic and correlation analyses revealed that the host genotype shaped the assembly of functionally distinct rhizosphere microbiomes. The SX cultivar assembled a sulfur-cycling anaerobic microbiota, enriched with methanogenic archaea (e.g., Methanothrix ) and the sulfate-reducing bacterium Desulfovibrio -forming a consortium implicated in reducing Cd bioavailability. In contrast, the QL cultivar enriched a heterotrophic, carbon-metabolizing microbiota, characterized by organic matter-degrading bacteria (e.g., Labilithrix ), suggesting a role in Cd complexation. Beta-diversity analysis confirmed that varietal differences were a key factor shaping microbial community structure. Co-occurrence network analysis linked these community shifts to Cd distribution, identifying specific taxa (e.g., Betaproteobacteria and Chloroflexota ) with opposing correlations to aerial tissue Cd content. Conclusions Together, these results demonstrate that host genotype shapes rhizosphere Microbiome assembly to modulate cadmium translocation in rice. This establishes a genotype-microbiota-function link, where host genotype shapes microbiome assembly, and the recruited microbial consortia, in turn, modulate Cd dynamics and translocation in rice.