EFFECT OF CADMIUM AND OR REMOVAL OF KERNELS OR SHOOTS ON THE LEVELS OF CYSTEINE, GAMMA-GLUTAMYL-CYSTEINE, GLUTATHIONE, AND TCA-SOLUBLE THIOLS IN MAIZE SEEDLINGS

Six day old maize seedlings (Zea mays L.) were exposed as intact plant s (A), after the removal of kernels (B) or shoots (C) or after the rem oval of kernels and transfer into the dark (D) to 0 or 50 micromolar c admium for 2 days. The roots were analyzed for fresh weight, total TCA -soluble thiols (including phytochelatins), glutathione, and its precu rsor compounds cysteine and gamma-glutamyl-cysteine. With all treatmen ts, cadmium caused an increase in the contents of cysteine, gamma-glut amyl-cysteine and total TCA-soluble thiols and a decrease in glutathio ne content. Our data indicate that the roots are at least in part auto nomous to provide the thiols required for phytochelatin synthesis.