Herbicide safeners selectively protect crops from herbicide injury while maintaining the\nherbicidal effect on the target weed. To some extent, the detoxification of herbicides is related to the\neffect of herbicide safeners on the level and activity of herbicide target enzymes. In this work, the\nexpression of the detoxifying enzyme glutathione S-transferase (GST) and antioxidant enzyme\nactivities in maize seedlings were studied in the presence of three potential herbicide safeners: 3-\ndichloroacetyl oxazolidine and its two optical isomers. Further, the protective effect of chiral\nherbicide safeners on detoxifying chlorsulfuron in maize was evaluated. All safeners increased the\nexpression levels of herbicide detoxifying enzymes, including GST, catalase (CAT), and peroxidase\n(POD) to reduce sulfonylurea herbicide phytotoxicity in maize seedlings. Our results indicate that\nthe R-isomer of 3-(dichloroacetyl)-2,2,5-trimethyl-1,3-oxazolidine can induce glutathione (GSH)\nproduction, GST activity, and the ability of GST to react with the substrate 1-chloro-2,4-\ndinitrobenzene (CDNB) in maize, meaning that the R-isomer can protect maize from damage by\nchlorsulfuron. Information about antioxidative enzyme activity was obtained to determine the role\nof chiral safeners in overcoming the oxidative stress in maize attributed to herbicides. The\ninteraction of safeners and active target sites of acetolactate synthase (ALS) was demonstrated by\nmolecular docking modeling, which indicated that both isomers could form a good interaction with\nALS. Our findings suggest that the detoxification mechanism of chiral safeners might involve the\ninduction of the activity of herbicide detoxifying enzymes as well as the completion of the target\nactive site between the safener and chlorsulfuron.
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