Morphological effects of zinc and its accumulation in micropropagated plants of Paulownia tomentosa (Thunb.) Steud.

In vitro essay of Paulownia tomentosa (Thunb.) Steud. was undertaken to determine the capacity of this medicinal plant to accumulate heavy metal in its tissues. In this case, the nodal explants were placed on Murashige and Skoog’s medium (1962), added with 1.0 mg l-1 indole-3-butyric acid (IBA). The ZnSO4 was supplemented to the culture medium at various concentrations 200, 400, 600, 800 and 1000 μM. The MS medium free of Zn was served as control. The height of plantlets, the number of nodes, the number and length of roots and the biomass of the in vitro plants were determined. The Zn content in plant tissues was measured by an inductively coupled plasma-optical emission spectrometer (ICP-OES, OPTIMA 2000 DV, PerkinElmer, USA). Results showed that highest Zn level (1000 μM) induced a significant reduction in shoot height, (18.86%) and root number (84.9%) of plantlets in comparison to the control. The highest Zn concentration in the culture medium caused also an important decrease in fresh and dry biomass by 22.8% and 50.5%, respectively compared to the control. Furthermore, a high Zn accumulation in the plantlet tissues which varied from 121μg/g dry matter (DM) in the control to 2580 μg/g (DM) in the presence of 1000 μM Zn was noticed. Consequently, Paulownia tomentosa could be considered as a bio-indicator and Zn accumulator medicinal plant.