Rising tropospheric ozone concentrations ([O₃]) can lead to considerable damage to agricultural crops. The phytotoxicity of O₃ comes from its high oxidative capacity through the induction of reactive oxygen species (ROS) in exposed plant tissue. The ascorbate-glutathione (AsA-GSH) cycle has an important function in eliminating H₂O₂, and the metabolism of the AsA-GSH cycle can be stimulated in plants by moderating stress conditions to scavenge ROS. 

Rice (Oryza sativa L.) is one of the most important food crops in the world. An O₃-free-air controlled enrichment (O₃-FACE) platform developed by the research group led by Prof. ZHU Jianguo provides more natural field conditions than pots, and plants are continuously exposed to elevated O₃ concentration [O₃] that fluctuates in accordance with ambient [O₃]. Previous O₃-FACE studies have reported that O₃ impacts the growth, yield, grain quality and photosynthetic characteristics of rice cultivars. The results suggest  relatively sensitive to O₃ and exhibit a significant yield loss, whereas inbred cultivars do not. In the present study, two rice cultivars with different responses to O₃ were studied to investigate the ROS metabolic system and AsA-GSH cycle using O₃-FACE technology. 

The results suggested that ROS detoxification by the AsA-GSH cycle under long-term exposure to an O₃-enriched atmosphere plays a more important role in an O₃-tolerant rice cultivar than in an O₃-sensitive rice cultivar and that a better understanding of antioxidant system mechanisms is essential to the assessment of different rice cultivars’ responses to future tropospheric [O₃].