A meta-analysis of elevated O3 effects on herbaceous plants antioxidant oxidase activity

Increases in near-surface ozone (O 3 ) concentrations is a global environmental problem. High-concentration O 3 induces stress in plants, which can lead to visible damage to plants, reduced photosynthesis, accelerated aging, inhibited growth, and can even plant death. However, its impact has not been comprehensively evaluated because of the response differences between individual plant species, environmental O 3 concentration, and duration of O 3 stress in plants. We used a meta-analysis approach based on 31 studies 343 observations) to examine the effects of elevated O 3 on malondialdehyde (MDA), superoxide dismutase (SOD), and peroxidase (POD) activities in herbaceous plants. Globally, important as they constitute the majority of the world’s food crops. We partitioned the variation in effect size found in the meta-analysis according to the presence of plant species (ornamental herb, rice, and wheat), O 3 concentration, and duration of O 3 stress in plants. Our results showed that the effects of elevated O 3 on plant membrane lipid peroxidation depending on plant species, O 3 concentration, and duration of O 3 stress in plants. The wheat SOD and POD activity was significantly lower compared to the herbs and rice ( P<0 . 01 ). The SOD activity of all herbaceous plants increased by 34.6%, 10.5%, and 26.3% for exposure times to elevated O 3 environments of 1–12, 13–30, and 31–60 days, respectively. When the exposure time was more than 60 days, SOD activity did not increase but significantly decreased by 12.1%. However, the POD activity of herbaceous plants increased by 30.4%, 57.3%, 21.9% and 5.81%, respectively, when exposure time of herbaceous plants in elevated O 3 environment was 1–12, 13–30, 31–60 and more than 60 days. Our meta-analysis revealed that (1) rice is more resistant to elevated O 3 than wheat and ornamental herbs likely because of the higher activity of antioxidant components (e.g., POD) in the symplasts, (2) exposure to elevated O 3 concentrations for >60 days, may result in antioxidant SOD ...