Pteris vittata, the first arsenic hyper-accumulator identified, has very strong ability to absorb the arsenic, so it is widely used in phytoremediation of arsenic contaminated soil. In addition to enhanced uptake, Pteris vittata also exhibit efficient arsenic translocation from roots to fronds. Arsenate reductase PvACR2 has been identified which played an important role in arsenate reduction process. However, the molecular mechanism of arsenate reduction and key arsenate reductase enzyme in fronds of Pteris vittata is still unclear.

Currently, we cloned two HAC (High Arsenic Content) homologous genes, PvHAC1 and PvHAC2, in Pteris vittata. PvHAC1 and PvHAC2 were predominantly expressed in fronds. PvHAC1 transcripts were strongly induced response to AsV exposure, no significant altered under AsIII treatment. Furthermore, we heterologous expressed PvHAC1 in ∆arsC E. coli mutant, which lacking the endogenous arsenate reductase. Under different concentrations of arsenate stress, heterologous expressing of PvHAC1 could complement the growth of mutants and significantly enhance the tolerance of the transformants to arsenate. The concentration of arsenite in the medium was also significantly higher than that of the control. Though prokaryotic expression system, the purified HAC1 protein has been shown to have arsenic reductase activity. PvHAC1-eGFP was localized in the nucleus and the cytoplasm.

In summary, PvHAC1 is an AsV reductase that is critical for AsV detoxification in Pteris vittata fronds. The functional identification of PvHAC1 provided an insight into enhancing plant arsenic tolerance and decreasing arsenic accumulation by genetic engineering in future.