Heavy Metal Uptake and Transport in Plants

Abstract

Plants have developed different biochemical systems to overcome the heavy metalinduced stresses. An increase in the metal ion concentration in soil, metallothioneins, stress proteins, etc. results into reactive oxygen species (ROS) production that ultimately leads to programmed cell death. To deal with such problems, plants have developed certain defense mechanisms or adaptation strategies including restriction of metal ion uptake, metal export from the plant, chelation and compartmentalization, etc. These processes involve metal transporters, i.e., copper transporter family, ZIP (ZRT-IRT-like protein) family, NRAMP (natural resistance-associated macrophage protein) family of transporters, MATE (multidrug and toxic compound extrusion) protein transporters, HMA (heavy metal ATPase) transporters, oligopeptide transporters, ABC (ATP-binding cassette) family of transporters, and cation-diffusion facilitator family of transporters. These transporters act through a series of signaling events like phosphorylation cascades, hormones, mitogen-activated protein kinases, and calcium-calmodulin systems, ultimately leading to the balance of nutrients in the plant necessary for its survival.Trace quantities of some heavy metals are essential for plant metabolism; however, at higher concentration they are potentially toxic to plants and soil ecosystem (Nagajyoti et al. 2010). Applying inorganic fertilizers leads to the buildup of metals in soils (Li et al. 2010b). Soil and sediments obtained from

A Comprehensive Review on the Heavy Metal Toxicity and Sequestration in Plants

“…Along with the ABC transporters, involvement of other transporters including multidrug and toxic compound extrusion (MATE) family proteins [ 189 , 190 ], zinc-iron permease ( ZIP) , iron-regulated transporters ( IRT1 ) [ 190 ], natural resistance-associated macrophage proteins (NRAMP), copper transporters (Ctr/COPT), and heavy metal ATPase (HMA) transporters [ 191 ] has also been highlighted in tolerance to HM toxicity. These metal transporters are involved in mediating metal intake and translocation in plants [ 192 ]. For instance, IRT1 (a Fe transporter gene) that belongs to the ZIP family has been identified in Arabidopsis that leads to high-affinity Fe uptake under Fe-deficient conditions [ 193 ] along with uptake of other heavy metals such as Cd and Zn [ 194 ].…”

Arbuscular Mycorrhizal Fungi Are an Influential Factor in Improving the Phytoremediation of Arsenic, Cadmium, Lead, and Chromium

“…Cr(VI), as a strong oxidizing with redox potential between 1.33 to 1.38, causes rapid production of reactive oxygen species (ROS) such as superoxide and hydroxyl radicals [188], and its negative effects on plants include changes in membrane structure and root damage, carbon uptake, antioxidant defence activity, nutrient uptake, DNA damage, ion transport imbalance, reduced photosynthesis and growth, and eventually plant death [39,186,189,190]. Plants have different mechanisms for combating the toxicity of Cr, and the most important of which is the chemical reduction of Cr(VI) to Cr(III), which can be carried out enzymatically and non-enzymatically [191]. The addition of salts containing Fe(III), animal manure, or organic acids to the culture medium helps the plants in this direction [9].…”

Comparative transcriptome analysis reveals key cadmium transport-related genes in roots of two pak choi (Brassica rapa L. ssp. chinensis) cultivars

“…The translocation of Cd in plants is mediated by transporters. Cd generally enters root cells through the transporters of Zn 2+ , Mn 2+ , Cu 2+ and Fe 2+ [ 7 , 35 ]. Several genes encoding Cd-related transporters have been identified from Arabidopsis [ 12 , 36 , 37 ], rice [ 38 ], wheat [ 39 ] and tobaccos [ 40 ].…”