Engineering tolerance and hyperaccumulation of arsenic in plants by combining arsenate reductase and gamma-glutamylcysteine synthetase expression.
We have developed a genetics-based phytoremediation strategy for arsenic in which the oxyanion arsenate is transported aboveground, reduced to arsenite, and sequestered in thiol-peptide complexes. The Escherichia coli arsC gene encodes arsenate reductase (ArsC), which catalyzes the glutathione (GSH)-coupled electrochemical reduction of arsenate to the more toxic arsenite. Arabidopsis thaliana plants transformed with the arsC gene expressed from a light-induced soybean rubisco promoter (SRS1p) strongly express ArsC protein in leaves, but not roots, and were consequently hypersensitive to arsenate. Arabidopsis plants expressing the E. coli gene encoding gamma-glutamylcysteine synthetase (gamma-ECS) from a strong constitutive actin promoter (ACT2p) were moderately tolerant to arsenic compared with wild type. However, plants expressing SRS1p/ArsC and ACT2p/gamma-ECS together showed substantially greater arsenic tolerance than gamma-ECS or wild-type plants. When grown on arsenic, these plants accumulated 4- to 17-fold greater fresh shoot weight and accumulated 2- to 3-fold more arsenic per gram of tissue than wild type or plants expressing gamma-ECS or ArsC alone. This arsenic remediation strategy should be applicable to a wide variety of plant species.
D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism*; D001149:Arsenates / Q000378:metabolism; D001151:Arsenic / Q000378:metabolism*; D053501:Arsenite Transporting ATPases; D001673:Biodegradation, Environmental; D004151:Dipeptides / Q000235:genetics / Q000378:metabolism*; D004361:Drug Tolerance / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D005818:Genetic Engineering / Q000379:methods; D016623:Ion Pumps / Q000235:genetics / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012016:Reference Values; D012037:Refuse Disposal / Q000379:methods; D012989:Soil Pollutants / Q000378:metabolism; D013045:Species Specificity; D014170:Transformation, Genetic; D014874:Water Pollutants, Chemical / Q000378:metabolism
D001149:Arsenates; D004151:Dipeptides; D016623:Ion Pumps; D009097:Multienzyme Complexes; D011994:Recombinant Proteins; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; D053501:Arsenite Transporting ATPases; C017341:gamma-glutamylcysteine; D001151:Arsenic; C025657:arsenic acid