The molecular mechanism underlying cadmium resistance in NHX1 transgenic Lemna turonifera was studied by comparative transcriptome analysis

Abstract

Cadmium (Cd) is one of the most toxic heavy metals, which poses a serious threat to the environment. Our previous studies revealed that transgenic Lemna turonifera (hereafter mentioned as Transgenic) over expressing Na+/H+ Antiporter (AtNHX1) gene was more tolerant to Cd2+ stress than the Wild type plants (WT). To further explore the molecular mechanism underlying cadmium resistance, comprehensive transcriptome analysis and comparison were performed. For RNA-Seq, the trannsgenic and WT were treated with 50 μM CdCl2 for 24 h. In total, 2247 differentially expressed unigenes (DEGs) including 1195 upregulated and 1052 downregulated ones were discovered between Transgenic and WT samples. The downregulated genes associated with the adventitious root (AR), lateral root (LR) and root hair (RH) initiation might have prevented the root from abscission. Calcium signaling and ROS accumulation were regulated in response to cadmium stress. Moreover, the activation of genes involved in the production of trehalose and R-S glutathione increased the cadmium resistance of duckweed. Downregulation of genes involved in the transport of Cd2+ and upregulation of genes involved in vacuolar sequestration might have resulted in increased tolerance of Transgenic over WT. These findings might provide new ideas for improving plant cadmium resistance and phytoremediation. Comparative transcriptome analysis was applied to study the involvement of NHX1 in Cadmium detoxification. The genes associated with root, calcium signal and cadmium transports were regulated in transgenic duckweed.