Poster: Heavy metals & phytoremediation

Abs # 56: Further characterization of zinc tolerance genes from the zinc/cadmium hyperaccumulator Thlaspi caerulescens

Presenter:	Klein, Melinda , mak44@cornell.edu
Authors	Klein, Melinda  (A)   Kochian, Leon  (B)
Affiliations:	(A): Department of Plant Biology, Cornell University (B): US Plant Soil and Nutrition Laboratory, USDA-ARS, Cornell University

The uptake of plant micronutrients requires a well-honed regulatory system that can accumulate adequate levels of these scarce metals for growth yet avoids accumulation to toxic concentrations. In hyperaccumulating plant species, this micronutrient homeostasis is altered resulting in plants that can accumulate metals far in excess of normal concentrations. One such species is Thlaspi caerulescens, a zinc/cadmium hyperaccumulator, that can accumulate up to 30,000 ppm zinc in the shoots without exhibiting any toxicity symptoms. Earlier studies have shown that this metal accumulating phenotype is due to modifications in uptake, transport and sequestration processes. T. caerulescens is considered an excellent model system to study mechanisms of micronutrient homeostasis and extreme metal tolerance because of these physiological alterations compared with non-hyperaccumulating species and because of its inclusion in the Brassicaceae (allowing for comparative genetic work in Arabidopsis thaliana). We are continuing work initially started as a functional complementation screen in Saccharomyces cerevisiae to identify T. caerulescens genes involved in zinc tolerance. From this screen we identified a 14-3-3 protein, a vesicle-related protein, a putative DNA binding protein and a SOS2-like protein kinase. These genes have been studied both in the heterologous yeast system and through altered regulation in A. thaliana. Current experimental results from both systems will be presented. This research is supported by NSF Integrative Plant Biology Grant #IBN-0129844.