Abstract

The present work was designed to select hyperaccumulator plants by in vitro breeding from transversal thin cell layers. The thin layer explants of Brassica napus cv. Jumbo were cultivated directly in the presence of ZnSO₄ at different concentrations (0.1 to 1 mM). Regenerated shoots were transferred into pots, acclimatized, and cultured in the greenhouse. After 3 weeks, the regenerants were treated with 2 mM of ZnSO₄ during 7 days. Growth parameters, guaiacol peroxidase activity (GPOX), malondialdehyde (MDA), polyamines (PAs) and pigment contents were evaluated. ZnSO₄ applied during the regeneration process influenced significantly both physiological and biochemical characteristics of regenerated plants. Particularly, an increase of Zn level in the tissue culture induced an increase in MDA content and GPOX activity in the leaves and a decrease in pigment contents. Exposure to 2 mM Zn induced 112% increase in free polyamines in the leaves and roots, while this increase was as high as 399% for plants regenerated in the presence of the metal.

Key words: Phytoremediation, hyperaccumulator, in vitro, polyamines, malondialdehyde, guaiacol peroxidase, zinc stress.