Metabolite-Mediated Rhizosphere-Endosphere Microbiome Shapes Genotype-Dependent Cadmium Accumulation via Coupled Chemical Immobilization and Microbial Detoxification.

Abstract

Cadmium (Cd) contamination threatens food safety, yet genotype-dependent Cd accumulation at the soil-root interface remains poorly understood. We integrated physiological profiling, metabolomics, density functional theory (DFT), and 16S rRNA sequencing to compare two amaranth cultivars, Quanhong (QH, low-Cd) and Liuye (LY, high-Cd). QH showed greater shoot biomass (6.84 g/plant) and stronger Cd exclusion (root/shoot Cd: 0.12/0.08 mg/kg), whereas LY developed a larger root system (1.42 vs 0.71 g/plant) and accumulated more Cd (0.26/0.16 mg/kg). QH promoted conversion of exchangeable Cd into stable residual fractions and enriched humic-like dissolved organic matter and 9-Oxo-ODE, which showed strong predicted Cd2+ binding (-22.34 kcal/mol), supporting its potential role in Cd immobilization. QH showed stronger host-associated microbial selection, enriching Bacillus and Streptomyces associated with sulfur metabolism and thiol-mediated metal sequestration, together with greater diversity and stability of root endophytes. These findings indicate coordinated chemical and microbial regulation contributing to the low-Cd phenotype of QH.

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