Enhanced Cd accumulation by Graphene oxide (GO) under Cd stress in duckweed

Effective phytoremediation by aquatic plant such as duckweed could be applied to solve Cd pollution. In the present study, the impact of Graphene oxide (GO) on the accumulation of Cd in duckweed has been studied. The response of duckweed was also investigated, concluding growth, Cd²⁺ flux, and gene expression response. Results showed that GO promoted the accumulation of Cd in duckweed. After 6 h of Cd enrichment in duckweed, Cd content was about 1.4 times that of the control group at fronds and 1.25 times that of the control group at roots, meanwhile, Cd content in the water system was 0.67 times that of the control group. The Cd²⁺ influx increased significantly. 4471 genes were up-regulated and 3230 genes were down-regulated significantly as duckweed treated with GO under Cd treatment. Moreover, phagosome pathway was downregulated, some key proteins: Stx7, Rab7 and Tubastatin B (TUBB) were significantly downregulated with GO addition under Cd stress. Scanning electron microscope (SEM) observation showed that GO and Cd were attached on the cell surface of duckweed as white crystal. GO could be applied in phytoremediation by duckweed of Cd in aquatic system.