Emissions of Biogenic Volatile Organic Compounds from Plants: Impacts of Air Pollutants and Environmental Variables

Purpose of Review: Biogenic volatile organic compounds (BVOCs) are essential for ecosystem functioning and climate. In natural environments, plants are exposed to a complex mixture of pollutants and environmental stressors, and combined exposure to these factors can produce effects that differ significantly from those of individual influences. However, comprehensive reviews on BVOC emission resulting from exposure to air pollution and its interactions with environmental variables remain limited. Recent Findings: Rapid industrialization has exacerbated air pollution, characterized by increased levels of ozone (O₃) and carbon dioxide (CO₂) in the atmosphere, along with extreme climatic events such as heat waves and droughts. These stresses induced by air pollution and environmental factors may trigger plant defense mechanisms, leading to adjustments in metabolism and respiration or may damage plant cells, ultimately affecting the composition and intensity of BVOC emissions. Summary: This review highlights that O₃ generally stimulates BVOC emissions, with a relatively smaller effect on isoprene but notable sensitivity in sesquiterpenes. In contrast, elevated CO₂ levels can suppress emissions across the three BVOC types investigated. Warming significantly boosts emissions, while drought has little effect on isoprene but substantially enhances sesquiterpene emissions. These analyses are limited by substantial uncertainties due to data scarcity. Additionally, the combined effects of air pollutants and environmental variables vary by plant species, VOC types, and stressor intensities. This review also summarizes current methodologies for investigating BVOC emissions, explores plant-pollutant-stressor interactions, identifies research gaps, and offers insights for advancing the understanding of stress-induced BVOC emissions in a changing environment and climate.