LAUSR

Abstract As essential source for human consumption, plants of wheat and rice are highly sensitive to ozone (O3), resulting in significant agricultural losses under O3 pollution. According to our results, photosynthesis and shoot biomass of wheat and rice were significantly reduced under elevated O3. The activities of SOD, POD and CAT were responsive to O3 pollution in two crops. However, little is known about the effects of elevated O3 concentration on their metabolite profiling. The response of metabolites to elevated ozone was investigated in model cultivars of wheat and rice. A total of 172 compounds significantly changed in seedlings of wheat (103) and rice (89) under O3 pollution. The strong up-regulation of phospholipids and markedly declined of fatty acids were detected in wheat and rice under elevated O3. Methylerythritol 4-phosphate pathway was altered in both crops with reduced accumulation of carbon compound terpene under O3 stress. Meanwhile, O3 treatment led to the high levels of aspartate-derived asparagine or aspartate, which regulated carbon and nitrogen metabolism. Additionally, O3 suppressed the generation of environmental stress-related flavonoids and cinnamic acids via shikimate pathway in the two crops. Moreover, the biosynthesis of sterols was suppressed and isocitrate was not changed under ozone fumigation in wheat, while both of them were increased in rice. The metabolic results reveal the involvement of O3-related metabolites in photosynthesis, oxidative stress and carbon/nitrogen balance. Our findings provide valuable information for understanding of ozone's effects on the physiology and metabolite profiling of crop plants, boosting efforts to screen genetic resources for valuable traits to adapt to O3 pollution.