Enantioselective effects of imazethapyr on the secondary metabolites and nutritional value of wheat seedlings Manxin Bao a , Jun Li a , Hui Chen b , Zunwei Chen c , Dongmei Xu d , Yuezhong Wen a, ⁎ a MOE Key Laboratory of Environmental Remediation & Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China b College of Science and Technology, Ningbo University, Ningbo 315211, China c Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843, United States d College of Biology and Environmental Engineering, Zhejiang Shuren University, Hangzhou 310015, China HIGHLIGHTS • IM caused enantioselective disturbances on the secondary metabolism and nutri- ents. • IM exposure activated phenylalanine pathway, which increased PAL enzyme activity. • R-IM raised antioxidant metabolites and trace elements but reduced DIMBOA and DF. • The decline in DIMBOA content may be a negative feedback regulation of excess Fe. • JA played a signal transduction role in the secondary metabolic disorders. GRAPHICAL ABSTRACT abstract article info Article history: Received 17 August 2020 Received in revised form 31 October 2020 Accepted 31 October 2020 Available online xxxx Editor: Shuzhen Zhang Keywords: Wheat Chiral pesticides Secondary metabolism Nutritional quality Bioactive substance The secondary metabolism of plants is key for mediating responses to environmental stress, but few studies have examined how the relationship between secondary metabolism and the stress response of plants is affected by exposure to chiral herbicides. Here, we studied the enantioselective disturbance of the chiral herbicide imazethapyr (IM) on the secondary metabolism and nutrient levels of wheat seedlings. The bioactive enantiomer R-IM significantly increased the contents of major secondary metabolites, including phenolic acids, flavonoids, and carotenoids but greatly inhibited the production of benzoxazine. The antioxidant system also responded strongly to R-IM; specifically, the activities of SOD, CAT, and GPX enzymes were all significantly induced, and the GSH content initially increased but then decreased. Furthermore, the nutrient levels of wheat seedlings were also affected; dietary fiber content decreased, while the contents of the microelements Fe, Mn, and Zn in- creased. In sum, this study provides new insight into the phytotoxic effects of IM and raises new questions on the role of secondary metabolites and nutrients in mediating enantioselective effects. © 2020 Elsevier B.V. All rights reserved. 1. Introduction Xenobiotic stress induced by environmental pollutants, such as pes- ticides, affects the dynamic homeostasis of endogenous substances, such as reactive oxygen species (ROS), and has adverse effects on plant growth. Plants transform these environmental stress signals into Science of the Total Environment xxx (xxxx) xxx Abbreviations: IM, imazethapyr; DF, dietary fiber; JA, jasmonic acid; PAL, phenylalanine aminolytic enzyme. ⁎ Corresponding author. E-mail address: wenyuezhong@zju.edu.cn (Y. Wen). STOTEN-143759; No of Pages 10 https://doi.org/10.1016/j.scitotenv.2020.143759 0048-9697/© 2020 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv Please cite this article as: M. Bao, J. Li, H. Chen, et al., Enantioselective effects of imazethapyr on the secondary metabolites and nutritional value of wheat ..., Science of the Total Environment, https://doi.org/10.1016/j.scitotenv.2020.143759