Atrazine and Mesotrione-Induced Oxidative Stress and Impact on Antioxidant Enzymes and Chlorophyll Contents in Bermudagrass

ABSTRACT: The effect of atrazine, mesotrione, and joint activity of atrazine plus mesotrione on pigment, lipid peroxidation, and antioxidant enzyme activity was studied. Atrazine and mesotrione treatments significantly reduced chlorophyll a (Chl a), chlorophyll b (Chl b), carotenoid concentrations, and protein content in bermudagrass (Cynodon dactylon L.) plants, whereas they significantly enhanced lipid peroxidation. The treatment of atrazine plus mesotrione caused greater phototoxic effect on bermudagrass than either herbicide alone, which was evident from the significantly decreased membrane stability noted as a function of the enhanced singlet oxygen and malondialdehyde (MDA) contents, as well as from the greater reduction in Chl a, Chl b, and carotenoid contents. Although bermudagrass activated the antioxidant enzymes catalase (CAT), peroxidase (POD), and glutathione S-transferase (GST), it was significantly injured after the herbicide treatments. Thus, results suggested that the enzymatic and non-enzymatic antioxidants of bermudagrass was overloaded after the treatment of atrazine plus mesotrione, and the reactive oxygen species (ROS) subsequently caused lipid peroxidation, pigment and protein degradation, as well as other cellular constituent damage.

摘要：本研究探讨了莠去津（atrazine）、硝磺草酮（mesotrione）及其复配使用对狗牙根（Cynodon dactylon L.）植株色素含量、脂质过氧化水平及抗氧化酶活性的影响。单独施用莠去津或硝磺草酮均会显著降低狗牙根的叶绿素a（Chl a）、叶绿素b（Chl b）、类胡萝卜素含量与蛋白质含量，同时显著提升脂质过氧化程度。莠去津与硝磺草酮复配处理对狗牙根的光毒性效应显著高于单一除草剂处理，该效应可通过以下证据得以体现：其一，膜稳定性显著下降，这与单线态氧与丙二醛（MDA）含量升高密切相关；其二，叶绿素a、叶绿素b及类胡萝卜素的含量降幅更为显著。尽管狗牙根可激活过氧化氢酶（CAT）、过氧化物酶（POD）与谷胱甘肽S-转移酶（GST）等抗氧化酶，但除草剂处理仍使其受到显著损伤。综上，研究结果表明，经莠去津与硝磺草酮复配处理后，狗牙根的酶促与非酶促抗氧化系统过载，活性氧（ROS）继而引发脂质过氧化、色素与蛋白质降解，以及其他细胞组分损伤。