Cd and Cu accumulation, translocation and tolerance in Populus alba clone (Villafranca) in autotrophic in vitro screening

The present study investigated accumulation, translocation and tolerance of autotrophic Populus alba clone "Villafranca" in response to excess concentrations of cadmium (Cd) and copper (Cu) provided to the plants. For this purpose, increasing concentrations of Cd (0, 5, 50 and 250 mu M) and Cu (0, 5, 50, 250 and 500 mu M) were administered to the growth medium in which micropropagated poplar plantlets were exposed to metal treatments for 15 days. Filter bags, instead of the conventional in vitro screening, were applied to improve the experimental design. Results showed that Cd and Cu increased in shoots and roots at increasing metal concentration in the medium. The highest Cd content was found in leaves, while the highest Cu content was found in roots. In "Villafranca", Cu showed toxic effects on the development of the seedlings, especially at the highest concentrations, reducing plant dry mass. However, the tolerance index (Ti) indicated good tolerance in this clone under exposure to excess metal concentrations, whereas plants had higher translocation factor (Tf). We recommend in vitro selection of tolerant genotypes, aimed at providing early indication on accumulation potentiality and tolerance capability in research on plant sensitivity to excess heavy metal concentrations.