Novel tools for remediation of heavy metal-contaminated soil and water using transgenic plants. CALS Impact Statement

Heavy detoxification in cells is contingent of chelation of heavy metals within the cytosol by specific cellular ligands and transport of ligand-metal complexes, either across plasma membrane (elimination) or across intracellular membranes (sequestration and compartmentation). We aim to identify the transport proteins in the model plant Arabidopsis thaliana that are responsible for the sequestration of heavy metals and their chelates into a specific subcellular compartment, the vacuole. Identified proteins will be used for generating transgenic plants for remediation of polluted with heavy metals soils and water. The major goal of this integrative project is to generate transgenic plants and to improve the existing remediation methods.

This project is stimulated by the fact although the adverse health effects of heavy metals (e.g. cadmium [Cd2+] and lead [Pb2+]) have been known for a long time, exposure to heavy metals continues and even increases in some areas due to the boost in their production and emission into the environment. As a result, hundreds of Superfund Sites in the United States, including sites in New York, which are agricultural soils, are on the National Priority List (NPL), (http://www.epa.gov/superfund) and are waiting for the clean-up. Physical soil and water remediation methods are expensive, impractical on the scale that is needed, and environmentally destructive. Phytoremediation is an alternative, cost-effective, and environmentally friendly approach that uses the ability of higher plants to extract and accumulate pollutants in a specific plant cell compartment (the vacuole), and/or convert them to less toxic forms. This project will contribute to developing novel phytoremediation tools for clean-up of polluted with heavy metals soils and water.

One of the first steps for generating transgenic plants for phytoremediation applications is to identify plant transport proteins that are involved in sequestration of metals into vacuoles. We have made significant progress towards this goal.
First: we have developed a rapid, double stranded (ds)RNA interference-based (RNAi) approach for targeted inactivation of genes using Arabidopsis protoplasts. This approach will be adapted to high-throughput screens for transport proteins involved in heavy metals detoxification. In addition, development of a rapid reverse-genetic approach for targeted inactivation of plant genes is timely and necessary for systematic analyzes of plants genes function. Initially designed for high-throughput screens for plant transport proteins that are involved in detoxification of environmental pollutants (e.g. heavy metals and xenobiotics), this approach could be extended to functional analyses of other genes, and thus, will become a valuable tool for the plant research community both, in academia and industry.
Second: We have already identified a transport protein, which activity is essential for cadmium detoxification. Currently we seek to determine the molecular mechanisms of its contribution to heavy metal detoxification.
Third: we established the procedure for growing plants in hydroponic cultures. Hydroponically-grown transgenic plants will be used for analyses of their heavy metal extracting and hyperaccumulating capacities.

There are at least two major outcomes from this project: First: This project will contribute to generating transgenic plants that will be used for cost-effective phytoremediation approaches for cleaning-up polluted with heavy metals sites. Generation of these transgenic plants, and their application to soil and ground water polluted with heavy metals in NYS, relates our project directly to CSREES National Goals, such as enhancing protection and safety of the nation’s agriculture and food supply, and protecting and enhancing the nation’s natural resource base and environment. Second: Development of RNAi in protoplasts as a rapid reverse-genetic approach for targeted inactivation of plant genes is timely and necessary for systematic analyzes of plants genes function. The genome sequence of Arabidopsis has been available for more than seven years, but only about 17% of genes have ascribed functions. The impeding step in their functional analyses is the availability of suitable reverse genetic tools. Commonly used approaches are limited by the time and space required to generate, isolate and maintain multiple mutant plant lines, and are not practical for rapid screens. RNAi in protoplasts, developed in the lab, allows rapid and high-throughput analyses of genes function that are time, space, and cost-efficient. This approach will become a valuable tool for the plant research community both, in academia and industry.

Hatch
Hatch Grant is not sufficient to cover expenses for this project. Therefore, this project is also partially covered by CALS Start-Up Grant

Overview