MOE Key Laboratory of Environmental Remediation & Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University , Hangzhou 310058, China.
Department of Veterinary Integrative Bioscience, Texas A&M University , College Station, Texas 77843, United States.
Environ Sci Technol. 2017 Oct 17;51(20):12007-12015. doi: 10.1021/acs.est.7b04252. Epub 2017 Sep 27.
The ecotoxicology effects of chiral herbicides have long been recognized and have drawn increasing attention. The toxic mechanisms of herbicides in plants are involved in production of reactive oxygen species (ROS) and cause damage to target enzymes, but the relationship between these two factors in the enantioselectivity of chiral herbicides has rarely been investigated. Furthermore, even though cytochromes P450 enzymes (CYP450s) have been related to the phytotoxicity of herbicides, their roles in the enantioselectivity of chiral herbicides have yet to be explored. To solve this puzzle, the CYP450s suicide inhibitor 1-aminobenzotriazole (ABT) was added to an exposure system made from dichlorprop (DCPP) enantiomers in the model plant Arabidopsis thaliana. The results indicated that different phytotoxicities of DCPP enantiomers by causing oxidative stress and acetyl-CoA carboxylase (ACCase) damage were observed in the presence and the absence of ABT. The addition of ABT decreased the toxicity of (R)-DCPP but was not significantly affected that of (S)-DCPP, resulting in smaller differences between enantiomers. Furthermore, profound differences were also observed in Fe uptake and distribution, exhibiting different distribution patterns in A. thaliana leaves exposed to DCPP and ABT, which helped bridge the relationship between ROS production and target enzyme ACCase damage through the function of CYP450s. These results offer an opportunity for a more-comprehensive understanding of chiral herbicide action mechanism and provide basic evidence for risk assessments of chiral herbicides in the environment.
手性除草剂的生态毒理学效应早已被认识到，并引起了越来越多的关注。除草剂在植物中的毒性机制涉及活性氧（ROS）的产生，并对靶酶造成损害，但在手性除草剂的对映体选择性中，这两个因素之间的关系很少被研究。此外，尽管细胞色素 P450 酶（CYP450s）与除草剂的植物毒性有关，但它们在手性除草剂对映体选择性中的作用尚未得到探索。为了解决这个难题，将细胞色素 P450 酶自杀抑制剂 1-氨基苯并三唑（ABT）添加到拟南芥模型植物中二氯丙酸（DCPP）对映体的暴露系统中。结果表明，在存在和不存在 ABT 的情况下，DCPP 对映体通过引起氧化应激和乙酰辅酶 A 羧化酶（ACCase）损伤表现出不同的植物毒性。添加 ABT 降低了（R）-DCPP 的毒性，但对（S）-DCPP 的毒性没有显著影响，导致对映体之间的差异更小。此外，铁的吸收和分布也存在明显差异，在暴露于 DCPP 和 ABT 的拟南芥叶片中表现出不同的分布模式，这有助于通过 CYP450s 的功能将 ROS 产生与靶酶 ACCase 损伤联系起来。这些结果为更全面地了解手性除草剂的作用机制提供了机会，并为环境中手性除草剂的风险评估提供了基础证据。
