Abstract
Food-based exposure to arsenic is a human carcinogen and can severely impact human health resulting in many cancerous diseases and various neurological and vascular disorders. This project is a part of our attempts to develop new varieties of crops for avoiding arsenic contaminated foods. For this purpose, we have previously identified four key genes, and molecular functions of two of these, AtACR2 and AtPCS1, have been studied based on both in silico and in vivo experiments. In the present study, a T-DNA tagged mutant, (SALK_143282C with mutation in AtACR2 gene) of Arabidopsis thaliana was studied for further verification of the function of AtACR2 gene. Semi-quantitative RT-PCR analyses revealed that this mutant exhibits a significantly reduced expression of the AtACR2 gene. When exposed to 100 mu M of arsenate (AsV) for three weeks, the mutant plants accumulated arsenic approximately three times higher (778 mu g/g d. wt.) than that observed in the control plants (235 mu g/g d. wt.). In contrast, when the plants were exposed to 100 mu M of arsenite (AsIII), no significant difference in arsenic accumulation was observed between the control and the mutant plants (535 mu g/g d. wt. and 498 mu g/g d. wt., respectively). Also, when arsenate and arsenite was measured separately either in shoots or roots, significant differences in accumulation of these substances were observed between the mutant and the control plants. These results suggest that AtACR2 gene is involved not only in accumulation of arsenic in plants, but also in conversion of arsenate to arsenite inside the plant cells.