ARS | Publication request: CLONING AND CHARACTERIZATION OF A HEAVY METAL TRANSPORTER IN THLASPI CAERULESCENS

Submitted to: American Society of Plant Physiologists Meeting
Publication Type: Abstract Only
Publication Acceptance Date: September 1, 1998
Publication Date: N/A

Technical Abstract: We have been conducting an integrated molecular and physiological investigation of heavy metal transport in the Zn/Cd hyperaccumulator, Thlaspi caerulescens, in order to elucidate mechanisms of metal hyperaccumulation and tolerance in plants. A Zn transport cDNA was cloned via functional complementation of a yeast mutant defective in Zn uptake. A Thlaspi caerulescens cDNA library was constructed in the yeast expression vector, pFL61, and 300,000 yeast transformants were screened for growth on low Zn media. This approach allowed us to clone a 1.2 kb Zn transport cDNA, ZNT1, from Thlaspi caerulescens. Sequence analysis of ZNT1 revealed that it shares significant homology both with IRT1, a putative Fe transporter from Arabidopsis, and ZRT1, a yeast high affinity Zn transporter. Initial characterization of the concentration-dependent kinetics of heavy metal transport via ZNT1 has shown that this system mediates both saturable Zn uptake and non-saturating Cd transport. We are currently investigating the relationship between plant micronutrient status, ZNT1 expression, and heavy metal hyperaccumulation.