Objective: Air pollution is one of the most severe environmental problems of developing cities which adversely affects both plant and human life. However, roadside plants in the urban locations help in reducing the pollution level from the air through foliar surface and act as pollution sink. In this work, an attempt was made to understand the impact of air pollution on urban roadside plants which act as bio indicator.
Methods:A study was conducted to check the impact of urbanization on air pollution by analyzing anatomical and biochemical aspects of Thevetia peruviana L. For anatomical analysis, the transverse sections of leaves were observed under a microscope; whereas for biochemical analysis, the estimation of chlorophyll, carotenoid and protein were determined by spectrophotometric methods. On the other hand, antioxidant enzyme assays, as well as specific activity staining, were performed to study the antioxidant potential. To investigate the antioxidant activity of the leaf extracts, an assay for catalase (CAT), guaiacol peroxidase (GPX) and superoxide dismutase (SOD) were performed. Isoforms of CAT, GPX and SOD were separated using native polyacrylamide gel electrophoresis (PAGE) and their activities were analyzed.Results: Analysis of data revealed that the anatomical disturbances significantly occurred in exposed plants of various sites. Among biochemical parameters, photosynthetic pigments such as chlorophyll a, chlorophyll b, total chlorophyll and carotenoid content were found to be decreased. A maximum (7.65±0.51, 3.78±0.56,11.43±0.91, 5.63±0.55 mg/g, respectively) decrement was noticed in leaves of the Pokhariput plant in comparison to Khorda NH5 (19.44±1.08, 10.12±1.03, 29.56±2.32, 10.22±1.21 mg/g, respectively) which is taken as control one. To determine the effect of air pollution on proteins, leaf extracts were analyzed by the Lowry method and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The substantial decrement of total protein and alteration in polypeptides were noticed in polluted sites. Meanwhile, the enhancement of antioxidant enzyme activities such as CAT, GPX and SOD were also detected.
Conclusion:The increment of antioxidant enzymes and alteration of proteins, suggesting the activation of defensive mechanisms in selected plants under air pollution stress and also the plants made physiological and biochemical adjustments to overcome the oxidative damage.