Superfund Research Program
A Novel Strategy for Arsenic Phytoremediation
Project Leaders: Om Parkash Dhankher, Venkataraman Dhandapani, Jason C. White, Baoshan Xing
Grant Number: R01ES032686
Funding Period: 2021-2025
Arsenic (As) contamination in the food chain is a global health problem and causes damage to most human organs. A significant need exists to develop approaches for addressing environmental arsenic. The long-term goal is to develop a plant-based phytoremediation approach for contaminated land that is cost-effective and ecologically friendly as an alternative to conventional remediation methods. The team aims to develop a genetics-based phytoremediation strategy for arsenic uptake, translocation, detoxification, and hyperaccumulation into the fast-growing, high biomass, non-food crop Crambe abyssinica.
The researchers will use nanosulfur to modulate the bioavailability and phytoextraction of As from soil and to increase the storage capacity via enhanced sulfur assimilation. The engineered Crambe will be evaluated for removing arsenic from the soil in laboratory, greenhouse, and field conditions. The central hypothesis of this project is that organ-specific expression of genes, which control the transport, oxidation state, and binding of As, can be tuned to yield efficient extraction and hyperaccumulation into above-ground plant tissues.
To test their hypothesis, the researchers will:
- Genetically engineer Crambe abyssinica lines for co-expressing the bacterial genes ArsC, gECS, and AtABCC1 and RNA interference suppression of endogenous arsenate reductase (CaACR2Ri).
- Evaluate the engineered Crambe lines for metalloids tolerance and accumulation.
- Synthesize and apply nanosulfur to modulate the bioavailability, phytoextraction, and accumulation of toxic metalloids.
- Conduct a pilot field study of engineered Crambe lines for phytoextraction on a contaminated site.
After initial screening in tissue culture media supplemented with metals, the best performing quadruple gene stacked (ArcS+gECS+AtABCC1+CaACR2Ri) Crambe lines with wild type controls will be tested using contaminated soils with arsenic as well as co-contaminants in greenhouse. A pilot field-scale study will then be carried out at a site contaminated with arsenic. The soil will be extensively characterized, and analysis for metal content and arsenic speciation will be determined using inductively coupled plasma mass spectrometry, chromatographic separation mass spectrometry, and X-ray Absorption Near-Edge Spectroscopy. Last, soil amendments with engineered nanosulfur will be used to evaluate the impacts on soil structure and contaminant availability and phytoextraction. Nanosulfur will also be foliarly applied to plants to increase the metal storage capacity via enhanced sulfur assimilation.
The expected outcome of this project is a mechanistic understanding of the biogeochemical and plant processes of arsenic remediation that connects key soil characteristics with the efficiency of phytoextraction and hyperaccumulation of arsenic. Insights from this study will enable efficient and effective phytoremediation approaches to minimize or remove arsenic contamination in the food chain and enhance public health.