# Phtyromediation of Toxic Metals: A Sustainable Green Solution for Clean Environment
## 6 Molecular Adaptation Mechanisms of Toxic Metals in Higher Plants  
Toxic metals such as Cd, Cu, and Fe harm plant cells because of their transitional nature, undermining oxidative potential and decreasing different biomolecules (e.g., GSH) [159; 160; 161; 162; 163]. The reaction of such biomolecules and other transition metals with harmful metals could improve the plant cell's redox state. Furthermore, some hazardous metals can directly divide genetic materials (e.g., RNAs and DNAs) and plant protein linkages. The poisonous natures of toxic metals that cause physical damage to plants are avoided by maintaining a minimal concentration of free metal ions in the plant cell [164]. Metal accumulations and translocation into the cell, followed by protein interactions with the metals and the formation of organic ligands, are some of the steps that regulate this ionic state optimization [161; 162]. Some transporter protein maintains the first two processes, metal accumulations, their translocation into the cell, and protein connections with \begin{table}
\begin{tabular}{c c c c} \hline
**Process** & **Plant Species** & **Metals** & **References** \\ \hline Phytodegradation & _Armoracia rusticana_ & As, Cu & [140] \\  & _Canadian wateraveed_ & Zn, Cu, Cd & [141] \\  & _Cypenus alternifolia_ & Fe, Pd, Cr, Cu & [142] \\  & _Cynodon acetylation_ & Mn, Cu, Fe, Pb & [143] \\  & _Giant duckced_ & Fe, Cr, Cu, Cd & [144] \\ Phytostabilization & _Agrostis capillaris_ & Cu, Pb & [145] \\  & _Arundo donax_ & Ni, Cd & [146] \\  & _Ascolepis_ sp. & Co, Cu & [137] \\  & _Brassica juncena_ & Pb, Cu, Zn & [147] \\  & _Epilojumid alomaei_ & Cu, Zn, Pb & [146] \\  & _Ergrostis_ sp. & Cr, Cd, Pb & [148] \\  & _Gladilous_ sp. & Cd, Pb & [137] \\  & _Haumminastrum_ sp. & Cu, Co, Ni & [137] \\  & _Iris sibrica_ & Ni, Co, Pb & [149] \\  & _Nicotiana tabacum_ & Cd, Cu & [142] \\  & _Nicotiana nustica_ & Cd, Cu & [150] \\  & _Silene vulgaris_ & Zn, Cu, Cd & [140] \\  & _Prragmites australis_ & Cu, Zn, Cr & [150] \\  & _Rose plant_ & Cr, Zn, Hg & [149] \\  & _Suada maritime_ & Cu, Zn & [112] \\  & _Satum alfredii_ & Zn, Cd & [151] \\  & _Sesvicum_ & Cd, Ni & [112] \\  & _Zamnchellia peltata_ & Cd, Ni & [145] \\ Phytovolitization & _Arabidopsis thaliana_ & Cd, Zn & [130] \\  & _Astragalus bisulcatus_ & Se, Pb & [112] \\  & _Brassica junca_ & Pb, Cu, Zn & [138] \\  & _Brassica napus_ & Cr, Cu, Pb & [130] \\  & _Cassia lora_ & Fe, Zn, Cu, Pb & [131] \\  & _Chura Canescens_ & Cr, Pb & [133] \\  & _Lriodendron tulipifera_ & Hg, Ni & [126] \\  & _Nicotiana tabacum_ & Pb, Cd, Cu & [128] \\  & _Pteris vittata_ & As, Cd & [139] \\  & _Stanley pinnata_ & Cr, As, Pb, Cu & [33] \\ Phytofiltration & _Eichhornaisses_ & Pb, Zn, Hg, Ni, Cd & [93] \\  & _Fontinalis antiprotein_ & Co, Cr, Cu, As & [151] \\  & _Helianths annuus_ & Cd, Ni, Zn & [152] \\  & _Limmodaris flava_ & Cu, Fe, Mn & [153,154] \\  & _Micranthemum_ & As, Cd & [143] \\  & _umbrosum_ & & \\  & _Phragmites australis_ & Cu, Cr, Ni, Fe & [155] \\  & _Pistia stratrices_ & Hg, Ag, Pb, Mn & [156] \\  & _Salix matsudana_ & Cu, Cd & [157; 158; 159] \\  & _Spirodela punctata_ & Cd, Cu, Zn & [153] \\ \hline \end{tabular}
\end{table} 
Table 3: \(Cont.\)the metals [165]. Zn and Fe regulated transport proteins (ZIP), toxic metal ATPase genes such as HMA2, HMA3, and HMA4, metal-binding proteins such as Cu-chaperone ATX1 proteins, metallothioneeins (MTs), and phytochelatins (PCs) are the most important transporter proteins [165; 166]. ZIPs have a critical role in the uptake and transport of divalent metal ions, which helps maintain homeostasis and equilibrium [167]. In the phytoremediation process, toxic metal ATPase genes are involved in metal uptake, translocation, and sequestration [168]. When combined with protein molecules, Cu binding domains are thought to aid in Cu intracellular homeostasis due to their Cu-chelating capabilities [169]. Furthermore, antioxidant proteins such as ATX1 and ATX2 have a high degree of sequence homology [169].