Mechanisms underlying arsenic tolerance and hyperaccumulation in the fern Pteris vittata

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Arsenic is a naturally occurring, toxic metalloid that is known to cause cancers if consumed. Arsenic contamination of soils and water is an environmental problem in many regions of the world, including the US. This research focuses on the fern Pteris vittata, which is remarkable because it and its close relatives are the only known multicellular organisms that are able to tolerate and accumulate very high levels of arsenic. The goals of this research are to understand how this plant is able to take up and store this toxin without succumbing to its deadly effects. Two genes isolated from this plant are hypothesized to be involved in this process. One is an arsenate reductase, which reduces the arsenate, which is taken up from the soil by the root, to arsenite. The other is an arsenite effluxer that is hypothesized to move arsenite into the vacuole of the cell where it is safely sequestered. One goal of this research is to express these genes in another arsenic-sensitive plant (Arabidopsis thaliana) to see if they are able to confer arsenic tolerance to other plants. A second goal is to localize the proteins produced by these genes at the tissue, cellular and subcellular levels in P. vittata. The final goal is to develop basic genomic tools for P. vittata that ultimately will allow us to identify other genes that are involved in arsenic tolerance and hyperaccumulation in this plant. This research has broader impacts in that it will identify a mechanism of arsenic tolerance and accumulation that may be of practical value in the remediation of arsenic contaminated soils. This research also will provide undergraduate and graduate students, including underrepresented minorities, interdisciplinary training in biochemistry, microscopy, genetics and molecular biology.