ARS | Publication request: EXPRESSION AND LOCALIZATION OF THE HEAVY METAL TRANSPORTER ZNT1 IN THLASPI CAERULESCENS, A ZINC HYPERACCUMULATOR

Submitted to: American Society of Plant Physiologists Meeting
Publication Type: Abstract Only
Publication Acceptance Date: July 1, 1999
Publication Date: N/A

Technical Abstract: The development of phytoremediation as an effective technology for contaminated soil clean up will benefit from the characterization of plant species that can tolerate and accumulate toxic metals and metalloids in the soil, such as zinc, cadmium, selenium, boron, and lead. Thlaspi caerulescens tolerates and accumulates tremendously high concentrations (up pto 40,000 ug/g) of Zn in its shoots. Previous physiological investigations in our lab have shown that a number of Zn transport sites are stimulated or altered in this hyperaccumulator species (e.g. root Zn influx, compartmentation in the root vacuole, loading into the xylem, and leaf Zn absorption). To begin a molecular characterization of the Zn transport and hyperaccumulation in T. caerulescens, the gene ZNT1 was recently cloned in our lab by complementation of a Zn uptake-deficient yeast mutant. Transport studies of ZNT1 in yeast showed it was a high affinity Zn transporter. ZNT1 1and a family of iron and Zn transporters from yeast and Arabidopsis were found to have significant sequence similarity. Northern analysis showed there is high transcript abundance in T. caerulescens versus low abundance of its homolog in a related non-accumulator, T. arvense. The next steps to demonstrating the links between ZNT1 expression and Zn uptake in both hyperaccumulating and non-hyperaccumulating plants are to study ZNT1 RNA and protein localization and abundance. Current research is underway to investigate in what cells ZNT1 is expressed and the subcellular location of the transport protein utilizing in situ hybridization and immunolocalization techniques. Our laboratory is also pursuing the cloning of additional ZNT1 homologs in both T. caerulescens and T. arvense.