Lead tolerance in plants: strategies for phytoremediation

Abstract

Lead (Pb) is naturally occurring element whose distribution in the environment occurs because of its extensive use in paints, petrol, explosives, sludge, and industrial wastes. In plants, Pb uptake and translocation occurs, causing toxic effects resulting in decrease of biomass production. Commonly plants may prevent the toxic effect of heavy metals by induction of various celular mechanisms such as adsorption to the cell wall, compartmentation in vacuoles, enhancement of the active efflux, or induction of higher levels of metal chelates like a protein complex (metallothioneins and phytochelatins), organic (citrates), and inorganic (sulphides) complexes. Phyotochelains (PC) are synthesized from glutathione (GSH) and such synthesis is due to transpeptidation of γ-glutamyl cysteinyl dipeptides from GSH by the action of a constitutively present enzyme, PC synthase. Phytochelatin binds to Pb ions leading to sequestration of Pb ions in plants and thus serves as an important component of the detoxification mechanism in plants. At cellular level, Pb induces accumulation of reactive oxygen species (ROS), as a result of imbalanced ROS production and ROS scavenging processes by imposing oxidative stress. ROS include superoxide radical (O2(.-)), hydrogen peroxide (H2O2) and hydroxyl radical ((·)OH), which are necessary for the correct functioning of plants; however, in excess they caused damage to biomolecules, such as membrane lipids, proteins, and nucleic acids among others. To limit the detrimental impact of Pb, efficient strategies like phytoremediation are required. In this review, it will discuss recent advancement and potential application of plants for lead removal from the environment.

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

“…Considering the low Pb concentrations in the solution, there was different growth of the species in response to the applied doses (Figure 1), confirming the fact that plant species respond differently to the exposure to Pb (Huang & Cunhingham, 1996;Alves et al, 2008;Zhivotovsky et al, 2011;Gupta et al, 2013).…”

“…The Pb toxicity observed in the present study is due to its action on plants, causing physiological, biochemical and structural disorders, such as disequilibrium in water and hormone balance, nutritional disorders, loss of membrane permeability, reduction of enzymatic activity, inhibition of respiration and photosynthesis, among others (Yadav, 2010;Gupta et al, 2013).…”

“…(Kabata-Pendias, 2010;Kacálková et al, 2014). Soil contamination with Pb can result in a series of environmental problems, including loss of vegetation, contamination of surface waters and aquifers, besides direct toxicity to microorganisms, animals and humans (Huang & Cunningham, 1996;Gupta et al, 2013). Thus, the rehabilitation of soils contaminated with this element is of great importance, due to its strong pressure on the equilibrium and quality of the ecosystems.…”

Effect of biochar amendments on As and Pb mobility and phytoavailability in contaminated mine technosols phytoremediated by Salix

“…This confinement to the roots could make it possible to avoid PTE toxicity (Gupta et al, 2013). It has been proposed that the exclusion mechanisms of willows can protect the plant photosynthesis apparatus (Borišev et al, 2008).…”

The ways to increase efficiency of soil bioremediation

“…They are major sulfur-containing classes of metal chelating ligands identified in plants and they play a significant role in plant metal tolerance [59,60]. According to Sriprang and Murooka [59], metal binding to proteins is site specific and it has been reported that hard metals preferentially bind to Asp and Glu rich proteins [61], while soft metals tend to bind to Cys and His rich proteins [62].…”