Biochemical and physiological responses of Pinus eldarica and Platanus orientalis leaves to air pollution in Tehran

Air pollution has advers impacts on human beings, animals and plants. Leves and flowers are the most sensetive part of plants which are used as bioindicator under air pollution stress. Reactive Oxygen Species (ROS) increases in stress conditions, subsequently, plants have various changes in their physiological and biochemical properties in response to air pollution. The present study was conducted to investigate the effects of air pollution on superoxide dismutase (SOD), ascorbate  peroxidase (APX), and guaiacol peroxidase (GPX) activities as well as chlorophyll and carotenoid contents of Pinus eldarica and Platanus orientalis leaves in Tehran. Results showed that SOD activity of Pinus eldarica in unpolluted area was less than that in polluted area, and also this value for Platanus orientalis in unpolluted area was less than that in polluted area. The highest and lowest APX activity was found in Pinus eldarica of polluted area  and Platanus orientalis of unpolluted area, respectively. In addition, GPX activity of Pinus eldarica was more than that of Platanus orientalis and this value in polluted area was more than unpollluted area for both species so that its maximum and minimum was respectively found in Pinus eldarica of polluted area and Platanus orientalis of unpolluted area. chlorophyll a, total chlorophyll, and carotenoid in polluted area was more than that in unpolluted area, while this value was not statistically significant for chlorophyll b. In general, free radicals are increased under stress conditions. Hence, the activity of antioxidants has significan impacts on alleviating the damages of ROS. Enzyme activity was increased, while chlorophyll and carotenoid content were decreased in both spices under pollurtion stress. It can be concluded that Tehran has high concentration of pollutants which can change biochemical and physiological properties of tree leaves.