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

•Graphene oxide (GO) enhanced the accumulation of Cd in duckweed under Cd stress, which could be applied in phytoremediation of Cd in aquatic system.•GO reduced the Cd toxicity to duckweed growth, and enhanced Cd2+ flux in the fronds and roots, suggesting a new function of GO in Cd tolerance and accumulation in duckweed.•4471 genes were up-regulated and 3230 genes were down-regulated significantly as duckweed treated with GO under Cd treatment.•Scanning electron microscope (SEM) observation showed that GO and Cd were attached on the fronds and root surface of 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.