LEAD-INDUCED CHANGES IN GLUTATHIONE AND PHYTOCHELATIN IN HYDRILLA-VERTICILLATA (IF) ROYLE

Effects of lead were studied on cysteine, acid-soluble thiol, glutathi one contents and synthesis of phytochelatins (PCs) In a submerged aqua tic macrophyte, Hydrilla verticillata grown under cultural conditions. All concentrations of Pb ranging from 0.5-10.0 mu M enhanced cysteine content and accumulation of acid-soluble thiols inside plant tissue a nd synthesis of phytochelatins. Isolated fractions of the Pb-binding c omplex indicated involvement of phytochelatins in Pb detoxification. T he synthesis of these peptides was concomitant with a decline in total glutathione content. Buthionine sulfoximine, an inhibitor of glutathi one synthesis, reduced accumulation of acid soluble thiols and total g lutathione content. However, the protein synthesis inhibitor cyclohexi mide did not affect initial accumulation of acid soluble;SH. Results i ndicated that PC synthesis was induced under lead stress utilizing glu tathione as a substrate.