THE ROLE OF PHYTOCHELATIN OVERPRODUCTION AND OF THE PUTATIVE VACUOLAR TRANSPORTER MRP3 IN CD TOLERANCE OF ARABIDOPSIS AND TOBACCO PLANTS

Phytochelatins (PCs) are metal binding peptides, enzymatically synthesized from gluthatione by PC synthase (PCS1). PCs are able to form specific complexes with Cd and other heavy metals in the cytosol, that are sequestered into the vacuoles by specific membrane transport proteins where metals are not harmful for the cell. We previously demonstrated that in tobacco seedlings PCS1 overexpression, leading to PC overproduction, increases Cd tolerance (1). In Arabidopsis thaliana Cd tolerance of PCS1 overexpressing seedlings is strongly dependent on growth conditions, possibly because PC content is 5 fold higher in wt arabidopsis compared to wt tobacco seedlings (Brunetti et al. manuscript in preparation).