Effects of Cadmium Stress on Root Exudates and Soil Rhizosphere Microorganisms of Rice (Oryza sativa L.) and Its Ecological Regulatory Mechanisms

Rice, one of the global staple food crops, is significantly affected in its growth by cadmium (Cd) contamination in soil. This study comprehensively investigated the impact of Cd stress on the root exudates and rhizospheric soil microorganisms of rice through non-targeted metabolomics and high-throughput 16S rRNA sequencing technologies, as well as the ecological regulatory mechanisms between them. Root exudates reflect proactive plant defenses and enhance these capabilities by attracting beneficial microorganisms, which play a pivotal role in plant detoxification. There were significant changes in root exudates under Cd stress, their chelation and rejection of Cd ions diminished the bioavailability within the plant system, thereby mitigating the phytotoxic effects of heavy metal stress and safeguarding the overall health of plants. Moreover, Proteobacteria (Lysobacter, Pseudaminobacter, and Sphingomonas) were recruited by the root exudates from rice as potential participants in plant tolerance and detoxification processes. These findings offer novel insights into the ecological adaptability mechanisms of rice under heavy metal stress and provide potential biomarkers and microbial resources for agricultural environmental regulation.