Abstract
Heavy metal pollution is not only a hazard to living organisms but also an important worldwide environmental concern. Experiments were performed to investigate the physiological mechanisms of magnetic (Fe3O4) nanoparticles (nano-Fe3O4) mitigation of the toxicity of heavy metals (Pb, Zn, Cd and Cu) in wheat seedlings. All the Petri dishes with germinating seedlings (1d) were covered, sealed with parafilm, and placed in a dark growth chamber. All parameters (seedling growth inhibition, heavy metal accumulation, enzymatic activities, and reducing effects of nano-Fe3O4 on heavy metal toxicity) were analyzed only after five days. The results showed that the tested heavy metals significantly affected the growth of wheat seedling by decreasing root length, shoot length and even death at 10 mM concentration in the case of Cd and Cu. Heavy metals exposure also showed that superoxide dismutase (SOD) and peroxidases (POD) activities decreased significantly when the malondialdehyde (MDA) content was significantly higher in wheat seedlings. Addition of magnetic (Fe3O4) nanoparticles (2000 mg/L) in each heavy metal solution (1 mM) significantly decreased the growth inhibition and activated protective mechanisms to reduce oxidative stress induced by heavy metals in the wheat seedlings. The reducing effects of nano-Fe3O4 against heavy metals stress could be dependent on the increase in the enzyme activity (SOD and POD). Their protective role was confirmed by the decrease in MDA content. The alleviating effect of nano-Fe3O4 is associated with their adsorption capacity of heavy metals.
Highlights
Heavy metal pollution is a hazard to living organisms and an important worldwide environmental concern [1,2,3,4]
Our findings suggest that the tested heavy metal toxicity induced growth inhibition and oxidative stress in wheat seedlings
The addition of nano-Fe3O4 significantly decreased root growth inhibition, and reduced and alleviated oxidative stress induced by the heavy metals tested in the wheat seedlings
Summary
Heavy metal pollution is a hazard to living organisms and an important worldwide environmental concern [1,2,3,4]. We hypothesized that different heavy metal (Pb, Zn, Cd and Cu) treatments may cause inhibition in root growth, and induce oxidative stress in the wheat seedlings. Under this stress, the inhibitory effects of the selected heavy metals would be reduced and the antioxidant mechanisms activated with the addition of magnetic (Fe3O4) nanoparticles (6 nm). To better understand the effects of nanoparticles on reducing the phytotoxicity of heavy metals, we conducted study with magnetic (Fe3O4) nanoparticles on the toxicity and oxidative stress induced by four heavy metals (Pb, Zn, Cd and Cu) to early seedling growth of wheat (Triticum aestivum L.).
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