Submitted to: American Society of Plant Biologists Annual Meeting
Publication Type: Abstract only
Publication Acceptance Date: 2/2/2002
Publication Date: 3/25/2002
Citation: PAPOYAN, A., PENCE, N., KOCHIAN, L.V. INVESTIGATING THE MOLECULAR AND PHYSIOLOGICAL BASIS FOR CD TOLERANCE IN THEHEAVY METAL HYPERACCUMULATING PLANT SPECIES, THLASPI CAERULESCENS. AMERICAN SOCIETY OF PLANT BIOLOGISTS ANNUAL MEETING. 2002. Interpretive Summary:
Technical Abstract: Thlaspi caerulescens is a Zn/Cd-hyperaccumulating plant species that can accumulate and tolerate up to 30,000 ppm Zn and 3,000 ppm Cd in their shoots without exhibiting toxicity symptoms. As part of an overall program aimed at elucidating the molecular and physiological mechanisms of heavy hyperaccumulation in T. caerulescens, the research described here is focused on identification of genes responsible for Cd tolerance, as well a a physiological characterization of Cd hyperaccumulation in T. caerulescens seedlings. The molecular component is based on yeast functional complementation. We have found that 100 iM Cd in the growth medium is lethal for our wild type yeast strains. We have complemented this yeast strain with a T. caerulescens cDNA library in the yeast expression vector, pFL61, and have identified a number of colonies of transformed yeast that grow well on this restrictive level of Cd. We are currently isolating the plasmids harboring the T. caerulescens cDNAs for sequencing and further molecular characterization. The physiological work is based on our recent observations that when T. caerulescens is grown on very high levels of Zn (500 iM) which down-regulate Zn uptake, we were surprised to find that Cd transport and accumulation were stimulated. This response will be examined in more detail, based on quantification of the concentration dependent kinetics of 109Cd2+ influx in roots of T. caerulescens seedlings grown on adequate (1 iM) and high (500 iM) levels of Zn. These studies will enable us to begin to investigate whether growth on very high levels of Zn induces a stimulated level of Cd tolerance and accumulation.