Molecular Mechanism of Heavy Metal Toxicity and Tolerance in Plants: Central Role of Glutathione in Detoxification of Reactive Oxygen Species and Methylglyoxal and in Heavy Metal Chelation

Abstract

<jats:p>Heavy metal (HM) toxicity is one of the major abiotic stresses leading to hazardous effects in plants. A common consequence of HM toxicity is the excessive accumulation of reactive oxygen species (ROS) and methylglyoxal (MG), both of which can cause peroxidation of lipids, oxidation of protein, inactivation of enzymes, DNA damage and/or interact with other vital constituents of plant cells. Higher plants have evolved a sophisticated antioxidant defense system and a glyoxalase system to scavenge ROS and MG. In addition, HMs that enter the cell may be sequestered by amino acids, organic acids, glutathione (GSH), or by specific metal-binding ligands. Being a central molecule of both the antioxidant defense system and the glyoxalase system, GSH is involved in both direct and indirect control of ROS and MG and their reaction products in plant cells, thus protecting the plant from HM-induced oxidative damage. Recent plant molecular studies have shown that GSH by itself and its metabolizing enzymes—notably glutathione<jats:italic>S</jats:italic>-transferase, glutathione peroxidase, dehydroascorbate reductase, glutathione reductase, glyoxalase I and glyoxalase II—act additively and coordinately for efficient protection against ROS- and MG-induced damage in addition to detoxification, complexation, chelation and compartmentation of HMs. The aim of this review is to integrate a recent understanding of physiological and biochemical mechanisms of HM-induced plant stress response and tolerance based on the findings of current plant molecular biology research.</jats:p>

Potential of sunflower, castor bean, common buckwheat and vetiver as lead phytoaccumulators

“…The compartmentalization in subcellular structures, the decrease in transport through the membrane and formation of chelating peptides rich in proteins, such as phytochelatins, are some of these mechanisms that help, directly or indirectly, plants tolerate the accumulation of Pb and other heavy metals (Yadav, 2010;Hossain et al, 2012;Gupta et al, 2013).…”

Study of interaction effect between triacontanol and nitric oxide on alleviating of oxidative stress arsenic toxicity in coriander seedlings

“…In addition, HMs may be sequestered by organic acids, glutathione (GSH) or by specific metal-binding ligands in cells. GSH as a central molecule of antioxidant defense systems is involved in either direct or indirect control of ROS and MG and their reaction products in plant cells, thus protecting the plant from HM-induced oxidative damage (Hossain et al 2012). Cells have evolved an elaborate system of enzymatic and non-enzymatic antioxidants which help to scavenge these indigenously generated ROS.…”

Heavy metal toxicity in rice and soybean plants cultivated in contaminated soil

“…These include restricting transport from the root to the leaf, accumulation in trichomes, exudates that can complex the heavy metals, type of link between the element and the cell wall component, intracellular production of compounds with chelating properties and active pumping to the vacuoles. These mechanisms can occur individually or simultaneously, conferring increased tolerance to stress caused by the presence of heavy metals (Yadav, 2010;Hossain et al, 2012).…”