Arabis paniculata has been reported as a hyperaccumulator and functions in cadmium (Cd) tolerance and accumulation. However, the genes involved in Cd stress resistance in A. paniculata are still unknown. In this work, genes of the natural resistanceassociated macrophage proteins (NRAMPs) were characterized in A. paniculata, and their evolutionary relationship and expression patterns were analysed. Expression profiles indicated that ApNRAMPs showed large differences in response to Cd stress. It was highly induced by Cd in root and shoot tissues. To investigate the function of ApNRAMP4 under Cd stress, ApNRAMP4 was cloned and expressed in yeast and Arabidopsis. The results indicated that yeast and Arabidopsis expressing ApNRAMP4 showed normal growth under Cd stress. In addition, transgenic yeast and Arabidopsis showed the ability to concentrate Cd. Under 20 μM CdCl₂, Cd concentrations in wild type (WT) and transgenic yeast were 3.11 and 5.92 mg/kg, respectively. Cd concentrations in root tissues of WTand transgenic Arabidopsis were 0.18 and0.54 mg/kg, respectively. In shoot tissues of WT and transgenic Arabidopsis, Cd concentrations were 0.13 and 0.49 mg/kg, respectively. This report provides genomic information on hyperaccumulator A. paniculata. In addition, the present work identified key NRAMP genes that may serve as resources for heavy metal phytoremediation.

Cadmium (Cd) is a common hazardous element that shows potential chronic toxicity in plants and animals. Arabis paniculata functioning as a hyperaccumulator has been found in the Yunnan–Guizhou plateau in China. This study characterizes the function of ApHIPP3 in A. paniculata to Cd stress, showing that the expression of ApHIPP3 was highly induced by Cd stress. Arabidopsis thaliana overexpressing ApHIPP3 showed stronger growth potential than wild type (WT). Cd accumulation capacity was significantly higher intransgenic A. thaliana than in WT. In addition, transgenic A. thaliana showed the ability to inhibit electrolyte leakage and eliminate reactive oxygen species (ROS). A strong interaction of ApHIPP3 with the clathrin heavy chain ApCHC1, which is known to play an important role in biotic and abiotic stresses, could be detected by a yeast two-hybrid assay. This was further confirmed by pull-down and co-immunoprecipitation (Co-IP) assays. Overall, these results demonstrate the function of ApHIPP3 to Cd stress and suggest a regulatory mechanism in response to Cd stress.