Effects of Heavy Metals on Assimilatory Sulfate Reduction in Pea Roots

The high content of cysteine in the heavy metal sequestring phytochelatins (ɣ-Glu-Cys)n Gly (n =2-11) led to the prediction that plants cultivated with heavy metals should contain increased levels of the enzymes involved in cysteine formation. Indeed, root sections of pea seedlings grown with Cd2+ contained adenosine 5'-phosphosulfate sulfotransferase activity that was up to almost 20 fold higher than in controls. There was a parallel increase in glutathione synthetase, indicating that glutathione (ɣ-Glu-Cys-Gly) is involved in phytochelatin synthesis