Expression of a metallothionein A1 gene of pisum sativum in white poplar enhances tolerance and accumulation of zinc and copper

Metallothioneins (MTs) play an important role in heavy metal detoxification and homeostasis of intracellular metal ions. Transgenic white poplar constitutively expressing the PsMTA1 gene from Pisum sativum for a MT-like protein, revealed increased tolerance to heavy metal toxicity In this study the performance of two transgenic clones and the non transformed clone Villafranca (NT) were evaluated and compared to the selected high performing clone AL22, in presence of toxic concentrations of zinc and copper. metal translocation and accumulation in roots and leaves were examined as well the the ability to respond to oxidative damage by activating the enzymatic antioxidant defenses. The PsMTA1 over-expression in poplar might promote in the cell conditions that limited ROS accumulation and toxic ions damage when exposed to HM so allowing their accumulation. The results further support a role for MT as ROS scavenger whose action results in an increased tolerance and hyperaccumulation of Zn and Cu in transgenic plants over-expressing the gene.