Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 6/1/2003
Publication Date: 11/7/2005
Citation: Letham, D.L., Pence, N.S., Lasat, M.M., Kochian, L.V. 2005. Molecular and physiological investigations of thlaspi caerulescens, a zn/cd hyperaccumulator. In: Roots and Soil Management: Interactions between Roots and the Soil, Agronomy Monograhph no 48. Book Chapter. p. 95-106. Interpretive Summary:
Technical Abstract: Certain plant species have evolved specialized mechanisms that allow them to grow and thrive on metalliferous soils and accumulate high levels of heavy metals in the shoots that are toxic to normal plants. One such plant species is Thlaspi caerulescens, a Zn and Cd hyperaccumulator, and its metal hyperaccumulation phenotype appears to involve both enhanced metal transport and metal tolerance, presumably mediated by metal chelation and sequestration. Hyperaccumulator plants are defined as plants that exhibit the ability to accumulate 100 fold higher levels of specific micronutrients and/or heavy metals compared with normal, non-accumulator species. Physiological and molecular investigations of T. caerulescens have shown that a number of Zn/Cd transport sites within the plant are enhanced or upregulated, leading to the hyperaccumulation phenotype. T. caerulescens Zn and Cd transporters have been isolated and characterized and the findings from these studies suggest that normal micronutrient homeostasis is altered in T. caerulescens. That is, the regulation of expression of micronutrient transporters by plant Zn status is altered, and this contributes to the extreme metal accumulation. Currently, work is underway to identify the genes/proteins as well as the regulatory networks involved in these processes. One goal of this research is to identify the hyperaccumulation genes in T. caerulescens so they can be utilized for engineering plants better suited for the phytoremediation of soils contaminated with toxic heavy metals. Furthermore, as T. caerulescens hyperaccumulates an essential micronutrient (Zn), these studies are providing us with a better understanding of the molecular regulation of micronutrient homeostasis and nutrition.