Lead induced changes in glutathione and phytochelatin in Hydrilla verticillata (l. f.) Royle

Effects of lead were studied on cysteine, acid-soluble thiol, glutathione contents and synthesis of phytochelatins (PCs) in a submerged aquatic macrophyte, Hydrilia verticillata grown under cultural conditions. All concentrations of Pb ranging from 0.5–10.0 μM enhanced cysteine content and accumulation of acid-soluble thiols inside plant tissue and synthesis of phytochelatins. Isolated fractions of the Pb-binding complex indicated involvement of phytochelatins in Pb detoxification. The synthesis of these peptides was concomitant with a decline in total glutathione content. Buthionine sulfoximine, an inhibitor of glutathione synthesis, reduced accumulation of acid soluble thiols and total glutathione content. However, the protein synthesis inhibitor cycloheximide did not affect initial accumulation of acid soluble -SH. Results indicated that PC synthesis was induced under lead stress utilizing glutathione as a substrate.