Effects of Air Pollution on Morphological, Biochemical, DNA, and Tolerance Ability of Roadside Plant Species

Air pollution is a severe problem in the modern world. Urbanization, industrialization, and traffic emit air pollutants such as carbon monoxide (CO), nitrous oxides (NOx), hydrocarbons (HCs), and particulate matter into the environment. Plants can absorb air pollutants through stomata. They adversely affect the various metabolic and physiological processes of plant species. This review describes the impact of air pollution on plant health, morphologically, physiologically, and genetically, and the tolerance ability of plants located along roadside areas. Many morphological effects, like chlorosis, necrosis, leaf area, stomatal clogging, plant productivity, leaf falling, and reduction in flower yield, are observed due to the influence of air pollution. Air pollutants also damage the DNA and affect the biochemicals of the plants, as well as pH, relative water content (RWC), simple sugar, ascorbic acid (AA), total chlorophyll content (TCH), proline, and polyamines. Some plants located under pollution stress can mitigate air pollution. Plants with higher APTI values are more tolerant of air pollution, while those with the lowest APTI values can be used as an indicator of the rate of air pollution. There is much morphological, biochemical, and DNA damage noted in this review. Different strategies can be used to diagnose the effects of air pollution in the future and develop green belts to mitigate air pollution in pollution-stressed areas.