Poster: Regulation of gene expression

Abs # 740: Designing Plants that Accumulate Mercury Aboveground Using an Engineered Root-Specific Expression System

Presenter:	Kim, Tehryung , trkim@phygen.co.kr
Authors	Kim, Tehryung  (A)   Balish, Rebecca S (A)   Heaton, Andrew  (A)   McKinney, Elizabeth  (A)   Dhankher, Om Parkash  (A)   Meagher, Richard B (A)
Affiliations:	(A): University Of Georgia

We have been exploring various scenarios using engineered plants to clean environmental pollutants from soil and water. One strategy for the phytoremediation of mercury species involves the electrochemical reduction in roots of Hg(II) to soluble gas Hg(0). Hg(0) will move up the transpiration stream followed by reoxidation and trapping of Hg(II) in leaves for later harvest. This hyperaccumulation strategy requires that the bacterial mercuric ion reductase gene merA be strongly expressed from all root tissues but not in above ground organs. We have engineered an actin promoter vector, A2pot, to contain bacterial lac operator sequences. Linked to a GUS reporter A2pot::GUS is strongly expressed in all vegetative Arabidopsis organs and tissues. In contrast, the constitutive expression of the A2pot:GUS reporter is restricted primarily to all root tissues, when a modified bacterial repressor lacIn with plant nuclear localization signals is expressed from the light-induced rubisco small subunit promoter vector, S1pt:lacIn. Root GUS activity was 100 fold greater than leaf activity for numerous independent T2 generation plants. A merA gene construct, A2pot::merA, is also expressed significantly higher in roots than in transgenic leaves in the presence of S1pt:lacIn. These merA plants are highly resistant to mercury This engineered root specific expression system has applications to many areas of plant biotechnology. We plan to construct mercury hyperaccumulator species for field use and phytoremediation .