College of Environment, Zhejiang University of Technology, Hangzhou 310014, PR China.
College of Environment, Zhejiang University of Technology, Hangzhou 310014, PR China; Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, PR China.
Sci Total Environ. 2019 Nov 20;692:723-731. doi: 10.1016/j.scitotenv.2019.07.333. Epub 2019 Jul 22.
The enantioselective effects of imazethapyr (IM) enantiomers on wheat seedlings in a hydroponic medium were studied. R-IM at 0.05mg/L exerted a stronger inhibitory effect on shoot weight and root weight than 0.05mg/L S-IM, suggesting that R-IM more severely inhibited growth. Oxidative damage, based on the anthocyanin content, malondialdehyde (MDA) content, antioxidant enzyme activities and transcript levels of antioxidant enzyme genes, were studied together with the cellular ultrastructure of wheat leaves. The anthocyanin and MDA contents in the R-IM treatment group were significantly increased compared with those in the control group, but no significant changes were observed in the S-IM treatment group. The antioxidant enzyme activities of CAT and SOD were inhibited by 0.32- and 0.73-fold, respectively, in the 14day R-IM treatment group compared to those in the control. However, the transcript levels of antioxidant enzyme genes, including CuZnSOD, POD and CAT, were downregulated in the 14day R-IM exposure group, but those of DHAR were not. The number and size of starch granules increased and chloroplast swelling was observed in wheat leaf cells after R-IM exposure, which showed that photosynthetic functions were potentially disturbed. These results directly or indirectly imply that R-IM exposure causes more oxidative stress and exerts a stronger negative effect on wheat than S-IM. A metabolomics approach revealed that the tricarboxylic acid cycle was heavily suppressed by R-IM treatment. Some amino acids (proline, threonine, lysine, valine) were increased by only the R-IM treatment, indicating the activation of antioxidant pathways. The decrease in a series of fatty acids implied that the cell membrane composition changed in response to R-IM. These results provide a deeper understanding of the enantioselective effects of IM enantiomers on the molecular and metabolic responses in wheat seedlings.
我们研究了咪草烟（IM）对映体在水培介质中对小麦幼苗的对映体选择性效应。浓度为 0.05mg/L 的 R-IM 对地上部鲜重和根鲜重的抑制作用强于浓度为 0.05mg/L 的 S-IM，表明 R-IM 更严重地抑制了生长。我们还研究了基于花色素苷含量、丙二醛（MDA）含量、抗氧化酶活性和抗氧化酶基因转录水平的氧化损伤，以及小麦叶片的细胞超微结构。与对照组相比，R-IM 处理组的花色素苷和 MDA 含量显著增加，但 S-IM 处理组没有显著变化。与对照组相比，14 天 R-IM 处理组 CAT 和 SOD 抗氧化酶活性分别抑制了 0.32 倍和 0.73 倍。然而，在 14 天 R-IM 暴露组中，抗氧化酶基因（CuZnSOD、POD 和 CAT）的转录水平下调，但 DHAR 的转录水平没有下调。暴露于 R-IM 后，小麦叶片细胞中的淀粉粒数量和大小增加，叶绿体肿胀，表明光合作用功能可能受到干扰。这些结果直接或间接表明，与 S-IM 相比，R-IM 暴露对小麦造成的氧化应激更大，负面影响更强。代谢组学方法表明，三羧酸循环被 R-IM 处理严重抑制。只有 R-IM 处理增加了一些氨基酸（脯氨酸、苏氨酸、赖氨酸、缬氨酸），表明抗氧化途径被激活。一系列脂肪酸的减少表明，细胞膜组成因 R-IM 而发生变化。这些结果为深入了解 IM 对映体在小麦幼苗中的分子和代谢反应的对映体选择性效应提供了依据。
