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BIOLOGICAL SCIENCES / ENVIRONMENTAL SCIENCES
Hyperaccumulation of arsenic in the shoots of Arabidopsis silenced for arsenate reductase (ACR2)
*Department of Genetics, University of Georgia, Athens, GA 30602-7223; and Department of Biochemistry and Molecular Biology, Wayne State University, Detroit, MI 48201
Communicated by Jeffrey L. Bennetzen, University of Georgia, Athens, GA, November 9, 2005 (received for review April 25, 2005)
Endogenous plant arsenate reductase (ACR) activity converts arsenate to arsenite in roots, immobilizing arsenic below ground. By blocking this activity, we hoped to construct plants that would mobilize more arsenate aboveground. We have identified a single gene in the Arabidopsis thaliana genome, ACR2, with moderate sequence homology to yeast arsenate reductase. Expression of ACR2 cDNA in Escherichia coli complemented the arsenate-resistant and arsenate-sensitive phenotypes of various bacterial ars operon mutants. RNA interference reduced ACR2 protein expression in Arabidopsis to as low as 2% of wild-type levels. The various knockdown plant lines were more sensitive to high concentrations of arsenate, but not arsenite, than wild type. The knockdown lines accumulated 10- to 16-fold more arsenic in shoots (350–500 ppm) and retained less arsenic in roots than wild type, when grown on arsenate medium with <8 ppm arsenic. Reducing expression of ACR2 homologs in tree, shrub, and grass species should play a vital role in the phytoremediation of environmental arsenic contamination.
Escherichia coli ArsC | drinking water | CDC25 | toxicant | arsenic pollution
Present address: Department of Plant, Soil, and Insect Sciences, University of Massachusetts, Amherst, MA 01002. Author contributions: O.P.D. and R.B.M. designed research; O.P.D. and E.C.M. performed research; B.P.R. contributed new reagents/analytic tools; and O.P.D. and R.B.M. wrote the paper.
Conflict of interest statement: No conflicts declared.
Data deposition: The sequence reported in this paper has been deposited in the GenBank database (accession no. NM_120425 and Arabidopsis thaliana chromosome V locus At5g03455).
To whom correspondence should be addressed. E-mail: meagher{at}uga.edu
© 2006 by The National Academy of Sciences of the USA
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