Abstract
We have demonstrated that Cd is detoxified in the Cd hyperaccumulating ecotype of Thlaspi caerulescens, Ganges by sequestering Cd into the vacuoles. However, transporters involved in this process have not been identified. Here, we functionally characterized a P-type ATPase, HMA3, which showed higher expression in Ganges than in Prayon, a non-Cd accumulating ecotype based on a cross-species microarray analysis. HMA3 from Ganges and Prayon shared 99% identity and both of them showed transport activity for Cd, but not for Zn in yeast expression system. TcHMA3 was expressed in both the roots and shoots and the expression level was not altered by high Zn or Cd exposure in both ecotypes. However, the expression was constitutively 4-times higher in Ganges than in Prayon. Transient expression of GFP fusion protein and western-blot analysis showed that TcHMA3 was localized on the tonoplast. These results suggest that TcHMA3 is involved in Cd transport into vacuoles.
