Sulfur-responsive promoter of sulfate transporter gene is potentially useful to detect and quantify selenate and chromate

Plant-based assays for monitoring contaminated environments provide inexpensive and nontechnical means of environmental analysis. Here we report a model system for monitoring selenium and chromium, which are highly toxic heavy metals for living organisms. The major forms of selenium and chromium in nature are selenate and chromate. As toxic analogs of sulfate, they cause sulfur deficiency in plants by inhibiting the uptake of sulfate from the environment. We used a fusion gene construct consisting of a sulfur-responsive promoter region of the high-affinity sulfate transporter SULTR1;2 from Arabidopsis and green fluorescent protein (GFP; P_SULTR1;2-GFP) to quantify the levels of selenate and chromate by GFP accumulation. The P_SULTR1;2-GFP transgenic Arabidopsis plants showed drastic increases in GFP with the addition of selenate or chromate to the medium. The increase in GFP was concentration-dependent relative to the amounts of contaminants in the medium, suggesting the potential of P_SULTR1;2-GFP plants as indicators in quantifying environmental selenate and chromate.