Microbial Community Restructuring and Functional Response in Giant Duckweed (Spirodela polyrhiza) Fronds Driven by...

As a typical heavy metal pollutant, cadmium (Cd) poses significant threats to ecosystems and human health. Giant duckweed (Spirodela polyrhiza), a small aquatic plant characterized by rapid growth and efficient heavy metal accumulation, holds great promise for phytoremediation. However, the mechanisms by which S. polyrhiza enriches Cd-particularly the contributions of its surface-associated microbiota-remain poorly understood. In this study, S. polyrhiza fronds were exposed to 0, 1, and 10 μM Cd, and we observed a concentration-dependent increase in the abundance of epiphytic microorganisms on the frond surfaces. High-throughput 16S rRNA gene sequencing revealed that Cd stress significantly altered the diversity of the frond-epiphytic bacterial community. Notably, the relative abundances of the genera Herbaspirillum, Enterobacter, and Pantoea increased significantly with rising Cd concentrations. Functional prediction using PICRUSt2 indicated enrichment under Cd stress of specific traits-such as the nitrate/nitrite transporter NarK, signal transduction mechanisms, and ion channel proteins-suggesting these taxa may actively participate in Cd uptake and tolerance. Together, our results reveal a synergistic S. polyrhiza-microbiome response to Cd and identify taxa/functions as targets and biomarkers for microbe-augmented remediation.