Overexpression of a novel Arabidopsis gene related to putative zinc-transporter genes from animals can lead to enhanced zinc resistance and accumulation

We describe the isolation of an Arabidopsis gene that is closely related to the animal ZnT genes (Zn transporter). The protein encoded by the ZAT (Zn transporter of Arabidopsis thaliana) gene has 398 amino acid residues and i s predicted to have six membrane-spanning domains. To obtain evidence for t he postulated function of the Arabidopsis gene, transgenic plants with the ZAT coding sequence under control of the cauliflower mosaic virus 35S promo ter were analyzed. Plants obtained with ZAT in the sense orientation exhibi ted enhanced Zn resistance and strongly increased Zn content in the roots u nder high Zn exposure. Antisense mRNA-producing plants were viable, with a wild-type level of Zn resistance and content, like plants expressing a trun cated coding sequence lacking the C-terminal cytoplasmic domain of the prot ein. The availability of ZAT can lead to a better understanding of the mech anism of Zn homeostasis and resistance in plants.