Université du Québec à Montréal, Department of Biological Sciences, GRIL - TOXEN, Ecotoxicology of Aquatic Microorganisms Laboratory, Succ. Centre-Ville, H3C 3P8, Montréal, Québec, Canada.
Environ Pollut. 2016 Nov;218:402-409. doi: 10.1016/j.envpol.2016.07.019. Epub 2016 Jul 18.
We investigated the physiological responses of Lemna minor plants exposed to glyphosate. The deleterious effects of this herbicide on photosynthesis, respiration, and pigment concentrations were related to glyphosate-induced oxidative stress through hydrogen peroxide (HO) accumulation. By using photosynthetic and respiratory electron transport chain (ETC) inhibitors we located the primary site of reactive oxygen species (ROS) production in plants exposed to 500 mg glyphosate l. Inhibition of mitochondrial ETC Complex I by rotenone reduced HO concentrations in glyphosate-treated plants. Complex III activity was very sensitive to glyphosate which appears to act much like antimycin A (an inhibitor of mitochondrial ETC Complex III) by shunting electrons from semiquinone to oxygen, with resulting ROS formation. Confocal evaluations for ROS localization showed that ROS are initially produced outside of the chloroplasts upon initial glyphosate exposure. Our results indicate that in addition to interfering with the shikimate pathway, glyphosate can induce oxidative stress in plants through HO formation by targeting the mitochondrial ETC, which would explain its observed effects on non-target organisms.
我们研究了暴露在草甘膦中的浮萍植物的生理反应。这种除草剂对光合作用、呼吸作用和色素浓度的有害影响与草甘膦诱导的氧化应激有关，通过过氧化氢（HO）积累。通过使用光合作用和呼吸电子传递链（ETC）抑制剂，我们定位了在 500mg 草甘膦/L 暴露下植物中产生活性氧（ROS）的主要部位。鱼藤酮抑制线粒体 ETC 复合物 I 减少了草甘膦处理植物中的 HO 浓度。复合物 III 对草甘膦非常敏感，它似乎通过将电子从半醌转移到氧上来发挥作用，类似于抗霉素 A（一种线粒体 ETC 复合物 III 的抑制剂），从而形成 ROS。ROS 定位的共焦评估表明，ROS 在最初接触草甘膦时首先在叶绿体之外产生。我们的结果表明，草甘膦除了干扰莽草酸途径外，还可以通过靶向线粒体 ETC 形成 HO 诱导植物中的氧化应激，这可以解释其对非靶标生物的观察到的影响。
