Submitted to: American Society of Plant Biologists Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 8/3/2002
Publication Date: 8/3/2002
Citation: KLEIN, M.A., PENCE, N.S., KOCHIAN, L.V. CHARACTERIZATION OF ZINC TOLERANCE GENES IN THE ZINC/CADMIUM HYPERACCUMULATOR, THLASPI CAERULESCENS. AMERICAN SOCIETY OF PLANT BIOLOGISTS ANNUAL MEETING. 2002. Interpretive Summary:
Technical Abstract: Thlaspi caerulescens, a heavy metal hyperaccumulating plant species, accumulates up to 30,000 ppm zinc in the above ground biomass without exhibiting toxicity symptoms. Previous work in our lab has shown that altered regulation of micronutrient uptake, transport and sequestration in this species plays a key role in the hyperaccumulation phenotype. Thus, T. caerulescens is an excellent model system to study mechanisms of micronutrient homeostasis and extreme metal tolerance. Additionally, as a member of the Brassicaceae, the rich genomic resources of Arabidopsis thaliana are readily accessible for comparative studies. For these reasons, our lab is examining the mechanisms of zinc uptake and tolerance in T. caerulescens to further provide insights into plant mineral nutrition and the use of plants in phytoremediation efforts. While previous research has shown increased uptake and transport of zinc from the roots to foliar tissue in T. caerulescens relative to non-accumulating species, the mechanism of sequestration and tolerance of these elevated metal concentrations within the plant are still unknown. We are examining the molecular basis for this metal tolerance through a screen based on functional complementation in yeast. Yeast were transformed with a T. caerulescens expression library, screened for growth on high levels of zinc, and putative zinc tolerance genes were isolated and identified. From the genes identified in the screen, we have narrowed our focus to four putative zinc tolerance genes including a 14-3-3 protein, a putative protein kinase, a vesicle related protein and a putative DNA binding protein. Current research efforts are focused on characterizing their activity both in T. caerulescens and A. thaliana. Supported by NSF Grant # IBN-0129844.