Induction of glutathione S-transferase activity in Norway spruce by xenobiotics and herbicide safeners

The conjugation of CDNB, DCNB, and CH₃I with glutathione is significant in protein extracts of Norway spruce (Picea abies L. Karst.) needles and can be attributed to the activity of glutathione S-transferases (GST, E.C. 2.5.1.18). The GST mediated conjugation of the mentioned substrates can be significantly enhanced by donation of xenobiotics and herbicide safeners in concentrations as low as 50 μM. Inductive effects appear to be coupled to the de-novo synthesis of proteins and may be different for GST isozymes. The conjugation of CDNB was stimulated by donations of CDNB, benoxacor or fluxofenim but the conjugation of DCNB was increased by benoxacor, fenclorim and fluxofenim, whereas CDNB was a potent inhibitor of DCNB-GST. Inductions of DCNB conjugation of 800 % above controls were obtained with fluxofenim.