Microbial community restructuring and transcriptional responses to acute stress in duckweed enhance lead phytoremediation

Lead (Pb) contamination in aquatic ecosystems poses a persistent threat to environmental quality and human health. Duckweed-mediated phytoremediation serves as a valuable model for exploring the short-term physiological endurance of aquatic macrophytes under extreme Pb stress in highly contaminated aqueous environments. However, the integrated mechanisms underlying Pb hyperaccumulation in this system remain insufficiently understood. In this study, we employed a combined physiological, microbiomic, and transcriptomic approach to investigate the acute stress responses of the hyperaccumulating duckweed Landoltia punctata . Non-invasive micro-test technology (NMT) demonstrated that this hyperaccumulation was driven by enhanced, root-specific Pb²⁺ uptake, with the Pb-hyperaccumulating genotype exhibiting a 36.08% higher net influx than the non-hyperaccumulating genotype. Meanwhile, Pb exposure induced pronounced kingdom-specific restructuring in the root-associated microbiome, characterized by bacterial specialization for potential detoxification and fungal transitions toward opportunistic saprotrophy. Transcriptomic profiling further revealed a transcriptional shift favoring defense pathways in the host, marked by the upregulation of core stress signaling and the repression of energy-intensive lipid metabolism to sustain essential structural barriers. Collectively, our findings indicate that this short-term physiological endurance involves a complex host-microbiome response, with causal relationships requiring further functional validation. These results provide mechanistic insights and a theoretical framework for future optimization of phytoremediation systems.