Millet potential to tolerate phenanthrene toxicity: Evaluation of the enzymatic and non-enzymatic responses

Phenanthrene is a well-known compound belonging to the group of polycyclic aromatic hydrocarbons (PAHs). This compound has three rings with a molecular weight of ۱۷۸.۲۲ g.mol-۱ and considers as a low molecular weight PAH. One of the common ways for phenanthrene to enter the human body is to breathe polluted air and eat plants infected with this compound. In fact, plants, as the first link in the food chain, are able to uptake, transport or transform these compounds and play a key role in their remediation. However, little is known about the physiological and biochemical effects of PAHs on plants, and in particular on how plants respond. Therefore, in the present work, the toxic effects of phenanthrene on biochemical responses, including the study of the activity of enzymatic and non-enzymatic antioxidant compounds of Panicum miliaceum were studied. For this purpose, the seeds of this plant were hydroponically planted under different concentrations of phenanthrene (۰, ۵۰۰, ۱۰۰۰, ۱۵۰۰, and ۲۰۰۰ ppm) and then the studies were performed. Based on the results of the present study, the activity of antioxidant enzymes increased (catalase, peroxidase, superoxide dismutase and ascorbate peroxidase). At higher concentrations (۲۰۰۰ and ۱۵۰۰ ppm), H۲O۲ content increased despite a decrease in MDA content. Moreover, phenanthrene had no effect on the phenol content of the root and flavonoids of the aerial parts, as well as the protein content of the aerial and root organs (except for the reduction in the protein content of the aerial parts at ۲۰۰۰ ppm). Overall, phenanthrene caused concentration-dependent oxidative stress, meaning that only higher concentrations of phenanthrene caused oxidative stress. In conclusion, phenanthrene is not a very toxic compound to millet, in fact, the antioxidant system of the plant is probably strong enough that even counteract reactive oxygen species production (ROS) in higher concentrations of phenanthrene.

کلیدواژه ها:

Oxidative stress ، Antioxidant response ، Polycyclic aromatic hydrocarbons ، Crop plant