Detoxification and Accumulation of Cadmium and Arsenic in Plants : : Implications for Phytoremediation and Limiting Accumulation in Foods

Many of the metals and metalloids commonly used by our modern society are extremely toxic and can pose a significant health risk if consumed. However, unlike animals, some plants are often extremely tolerant to the toxic effects of these metals and can accumulate large amounts in various tissues. Because some plants can bioaccumulate toxic metals, a number of bioremediation strategies using plants have been proposed. However, accumulation of toxic metals in agronomic crops is not desirable. In fact, interest is growing within the plant breeding community to reduce the accumulation of toxic metals in key crops. Whether we are interested in increasing accumulation for remediation, or reducing accumulation for human consumption, understanding the molecular and genetic mechanisms underlying toxic metal sensing, uptake, detoxification, and storage are paramount for success. This dissertation outlines the systematic approaches we have taken to understand many of these processes. In the first part of this dissertation, the cloning and screening of cadmium/arsenic-inducible promoter elements using a genome-wide yeast one-hybrid approach along with microarray analyses of known mutants are presented. This is a continuation of the work presented in Appendix 1, which focuses on developing a cadmium/arsenic-inducible reporter line and screening, identifying, and characterizing new mutants in the glutathione biosynthesis pathway. Appendix 2 is a review article highlighting recent advances in the field of toxic metal tolerance and presents key gaps in our knowledg