# Role of Melatonin to Enhance Phytoremediation Capacity
## 3 Metals as a Severe Abiotic Stress and Effects Induced by Melatonin in Plants
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Stress Type** & **Plant Species** & **Melatonin Treatment (uM)** & **Effects Observed** & **Reference** \\ \hline Cd & Alkal & 10-20 & \(\uparrow\) tolerance, growth, phosphorus, CL transformers, \(\uparrow\) Cd roots, ROS & [7] \\ Cd & Rice & MOE * & \(\uparrow\) tolerance, growth, photosynthesis, redox balance, panicle number, grain yield & [58, 59] \\ Cd & Tomato & 25-500 & \(\uparrow\) CL tolerance, phosphodechates, ATPase activity & [60] \\ Cd & Tomato & MOE & \(\uparrow\) CL tolerance, heat-shock factor Als, induced by melatonin & [61] \\ Cd & Tomato & 25 & \(\uparrow\) CL tolerance, nucleation biosynthesis, I Cd leaf & [62] \\ Cd & Tomato & 100 & \(\uparrow\) CL tolerance, melatonin biosynthesis, spatula, S assimilation, antioxidant enzymes, & [63] \\ Cd & Wheat & 100 & \(\uparrow\) tolerance, antioxidant enzymes, ASA, CSH, I ROS & [64] \\ Cd & Wheat & 50-100 & \(\uparrow\) tolerance, plant growth, Chls, PSII & [65] \\ \hline \multirow{2}{*}{_Makelium quantitative and Calinesgrat performa_} & \multirow{2}{*}{100–200} & \multirow{2}{*}{\(\uparrow\) tolerance, biomass, Chls, antioxidant enzymes, Cd shoots concentration dependent} & [54] \\  & & & & \(\uparrow\) plant growth, Cd leaves, shoots, stenosis, antioxidant enzymes & [55] \\ Cd & _Cyphanium betrace_ & 50-150 & \(\uparrow\) not show biomass, Chls, antioxidant enzymes, soluble protein, Cd root and shoot & [66] \\  & _Finite patterns_ & 100-200 & \(\uparrow\) growth, photosynthesis, electrolyte leakage, phytocholatins, GSH, I ROS, Cd leaf & [66] \\ CdSe & Tomato & MOE & \(\uparrow\) growth, photosynthesis, electrolyte leakage, phytocholatins, GSH, I ROS, Cd leaf & [66] \\ Cd/Zn & Valerian and & 1000 & \(\uparrow\) Tolerance, plant growth, antioxidant enzymes & [67] \\  & Lemen balm & & & \(\uparrow\) formation, growth, 1 membrane peroxidation & [68] \\ Cu & Rat cabbage & 1-100 & \(\uparrow\) tolerance, growth, Cu- sequestration, TCA, ATP, GSH, I ROS & [69] \\ Cu & Caucumber & 0.01 & \(\uparrow\) plant survival & [53] \\ Cu & Pca & 5 & \(\uparrow\) plant survival & [53] \\ Zn & Wheat & 1000 & \(\uparrow\) tolerance, Chls, photosynthesis, Rubisco, ATPase & [70] \\ Al & Soybean & 0.1-1 & \(\uparrow\) tolerance, root growth, antioxidant enzymes, compression, \(\downarrow\) ROS & [71] \\ Al & _Arallopsis_ & 1-10 & \(\uparrow\) tolerance, root growth, cell division & [72] \\ Pb & Maize & 50-100 & \(\uparrow\) tolerance, growth, photosynthesis, Chls, RWC, K Ca levels, I ROS, MDA & [73] \\ Pb & Bermudagrass & 20-100 & \(\uparrow\) tolerance, biomass, Chls, RWC, AsA, CSH, antioxidant enzymes, I ROS, lipid & [74] \\  & & & & \(\uparrow\) percentage, proportional & \\ V & Watermelon & 0.1 & \(\uparrow\) tolerance, growth, photosynthesis, antioxidant enzymes, \(\downarrow\) I level, V transport, ROS, MDA & [75] \\ Boron & Pepper & 1 & \(\uparrow\)\(\uparrow\) tolerance, growth, photosynthesis, antioxidant enzymes, carotenoids, I B in leaf and fruit, Georgia, ROS, MDA & [76] \\ Boron & Spinach & 100–300 & \(\uparrow\) tolerance, growth, photosynthesis, RWC, CO uptake, sugars, carotenoids, redox balance, I ROS, MDA & [77] \\  & & & & \(\uparrow\) tolerance, growth, antioxidant enzymes, protein, proline, ASA, CSH, antioxidant enzymes, genomic metabolite stability, I ROS, and death, lipid peroxidation, lipase activity, DNA polymorphism & [78] \\ Alkalinity & Apple & 5 & \(\uparrow\) tolerance, root system, redox balance, polyamines & [79] \\ Alkalinity & Tomato & 0.25–1 & \(\uparrow\) seedling growth, photosynthesis, ion homeostasis, Na\({}^{+}\) identification, dehydration resistance, ROS homeostasis, \(DRE21\) and \(IA/AS\) transcription factors & [80, 81] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Studies of responses to melatonin treatments in the presence of several metals (or others) by different plant species.