The relation between loss of glutathione due to metal-induced phytochelatin synthesis and oxidative stress was studied in the roots of copper-sensitive and tolerant Silene cucubalus (L.) Wib., resistant to 1 and 40 micromolar Cu, respectively. The amount of nonprotein sulfhydryl compounds other than glutathione was taken as a measure of phytochelatins. At a supply of 20 micromolar Cu, which is ...

Phytochelatins are the principal heavy metal-detoxifying components in plants. To investigate phytochelatin (PHC) production and the importance of these compounds for heavy metal tolerance, sunflower (Helianthus annuus) was exposed to cadmium. The leaves and roots of sunflower plants cultivated in the presence of 15, 25 and 50 M Cd(NO3)2 for 3 and 9 days showed increased tolerance to cadmium an...

Cell suspension cultures of tomato, Lycopersicon esculentum Mill. cv VFNT-Cherry, produce phytochelatins (poly[gamma-glutamylcysteinyl]glycines) when exposed to cadmium. The synthesis of these peptides is accompanied by a decline in cellular levels of glutathione. Buthionine sulfoximine, an inhibitor of glutathione synthesis, inhibits the sustained production of phytochelatins. However, phytoch...

We modeled dissolved phytochelatin concentrations by studying its exudation from phytoplankton and its removal from seawater. Exudation rates were obtained from experiments in which a marine diatom, Thalassiosira pseudonana, was grown in Cd-containing medium. Dissolved phytochelatin in the culture medium was measured as a function of time, and a first-order model was fit to the data to derive e...

Cadmium (Cd) toxicity and production of different thiols (phytochelatins, glutathione, gamma-Glu-Cys and cysteine) were studied in the microalga Chlamydomonas moewusii exposed to different concentrations of this metal (1, 2, 4, 6, 8, and 10 mg/L) for 96 h. The inhibitory effect of Cd on growth was demonstrated. The value of EC50 (metal concentration which reduces the population growth to 50% of...

Arsenate tolerance is conferred by suppression of the high-affinity phosphate/arsenate uptake system, which greatly reduces arsenate influx in a number of higher plant species. Despite this suppressed uptake, arsenate-tolerant plants can still accumulate high levels of As over their lifetime, suggesting that constitutive detoxification mechanisms may be required. Phytochelatins are thiol-rich p...

Phytochelatins, a class of posttranslationally synthesized peptides, play a pivotal role in heavy metal, primarily Cd2+, tolerance in plants and fungi by chelating these substances and decreasing their free concentrations. Derived from glutathione and related thiols by the action of gamma-glutamylcysteine dipeptidyl transpeptidases (phytochelatin synthases; EC 2.3.2.15), phytochelatins consist ...