Ethylenediurea (EDU) pretreatment alleviated the adverse effects of elevated O3 on Populus alba ‘Berolinensis’ in an urban area

Authors: XU, SHENG - Chinese Academy Of Sciences; HE, XINGYUAN - Chinese Academy Of Sciences; Burkey, Kent; CHEN, WEI - Chinese Academy Of Sciences; LI, PIN - Chinese Academy Of Sciences; LI, YAN - Chinese Academy Of Sciences; LI, BO - Chinese Academy Of Sciences

Submitted to: Journal of Environmental Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/17/2019
Publication Date: 4/25/2019
Citation: Xu, S., He, X., Burkey, K.O., Chen, W., Li, P., Li, Y., Li, B. 2019. Ethylenediurea (EDU) pretreatment alleviated the adverse effects of elevated O3 on Populus alba ‘Berolinensis’ in an urban area. Journal of Environmental Science. 84:42-50.

Interpretive Summary: Ozone is an air pollutant that is toxic to plants, causing visible injury to foliage leading to reductions in the growth and yield of many agricultural, forestry and native species. Ground level ozone is formed from sunlight catalyzed reactions between oxygen in the air, volatile hydrocarbons and the nitrogen oxides produced during the burning of fossil fuels. Ozone is a regional problem because weather systems transport the pollutants to areas far beyond the site of origin. There are few strategies for adapting plants to ozone stress. Selecting for ozone tolerance is one option. Treating high-value plants with protective chemicals is another approach. In this study, a team of researchers from China and USDA-ARS conducted open-top chamber studies in Shenyang City in the northeast of China to test the effectiveness of ethylenediurea in protecting young hybrid poplar trees from ozone stress. Treatment of plants with ethylenediurea prior to exposure to moderate ozone levels prevented ozone-induced foliar injury and protected photosynthesis, demonstrating that protective chemicals are an effective approach for alleviating ozone stress.

Technical Abstract: Ethylenediurea (EDU) has been used as a chemical protectant of plants against ozone (O3). However, its protective effect and physiological mechanisms are still uncertain. The present study aimed to investigate the changes of foliar visible injury, physiological characteristics and volatile organic compounds (VOCs) emission rate in one-year-old Populus alba ‘Berolinensis’ seedlings with EDU pretreatments exposed to elevated O3 (EO, 120 micrograms m-3). The results showed that foliar visible injuries under EO were significantly alleviated in plants with EDU application (P < 0.05). Under EO, net photosynthetic rate, the maximum photochemical efficiency of PSII, and the actual photochemical efficiency of PSII with 300 and 600 mg L-1 EDU significantly increased compared to that without EDU pretreatment (P < 0.05), respectively. Malondialdehyde (MDA) content under EO without EDU pretreatment showed a highest level but decreased significantly by 14.9% and 21.3% with 300 and 600 mg L-1 EDU pretreatment, respectively. EO with 300 and 600 mg L-1 EDU pretreatment significantly increased superoxide dismutase (SOD) activity by 88.4% and 37.5%, respectively (P < 0.05). Abscisic acid (ABA) content under EO with EDU pretreatments was significantly higher than that without EDU pretreatment (P < 0.05). VOCs emission rate was higher up to 1.9 times and 95.5% under EO with 300 and 600 mg L-1 EDU pretreatment than that without EDU, respectively. These findings provided significant evidence that EDU exerted a beneficial effect and protection on the tested plants against O3 stress. Nevertheless, it may exert a potential risk of O3 precursor production.