耐受型玉米与多抗性水苋菜对 S-甲草氯解毒的代谢途径不同。
Metabolic Pathways for S-Metolachlor Detoxification Differ Between Tolerant Corn and Multiple-Resistant Waterhemp.
机构信息
Department of Crop Sciences, University of Illinois, Urbana, IL 61801, USA.
Jealott's Hill International Research Centre, Syngenta UK Ltd, Bracknell, Berkshire RG42, UK.
出版信息
Plant Cell Physiol. 2021 Dec 10;62(11):1770-1785. doi: 10.1093/pcp/pcab132.
Herbicide resistance in weeds can be conferred by target-site and/or non-target-site mechanisms, such as rapid metabolic detoxification. Resistance to the very-long-chain fatty acid-inhibiting herbicide, S-metolachlor, in multiple herbicide-resistant populations (CHR and SIR) of waterhemp (Amaranthus tuberculatus) is conferred by rapid metabolism compared with sensitive populations. However, enzymatic pathways for S-metolachlor metabolism in waterhemp are unknown. Enzyme assays using S-metolachlor were developed to determine the specific activities of glutathione S-transferases (GSTs) and cytochrome P450 monooxygenases (P450s) from CHR and SIR seedlings to compare with tolerant corn and sensitive waterhemp (WUS). GST activities were greater (∼2-fold) in CHR and SIR compared to WUS but much less than corn. In contrast, P450s in microsomal extracts from CHR and SIR formed O-demethylated S-metolachlor, and their NADPH-dependent specific activities were greater (>20-fold) than corn or WUS. Metabolite profiles of S-metolachlor generated via untargeted and targeted liquid chromatography-mass spectrometry from CHR and SIR differed from WUS, with greater relative abundances of O-demethylated S-metolachlor and O-demethylated S-metolachlor-glutathione conjugates formed by CHR and SIR. In summary, our results demonstrate that S-metolachlor metabolism in resistant waterhemp involves Phase I and Phase II metabolic activities acting in concert, but the initial O-demethylation reaction confers resistance.
杂草的除草剂抗性可以通过靶标和/或非靶标机制赋予，例如快速代谢解毒。与敏感种群相比，水花生（Amaranthus tuberculatus）的多个除草剂抗性种群（CHR 和 SIR）中对非常长链脂肪酸抑制型除草剂 S-甲草氯的抗性是通过快速代谢赋予的。然而，水花生中 S-甲草氯代谢的酶途径尚不清楚。使用 S-甲草氯开发了酶测定法，以确定 CHR 和 SIR 幼苗中谷胱甘肽 S-转移酶（GSTs）和细胞色素 P450 单加氧酶（P450s）的比活性，以与耐受玉米和敏感水花生（WUS）进行比较。与 WUS 相比，CHR 和 SIR 的 GST 活性更高（约 2 倍），但远低于玉米。相比之下，CHR 和 SIR 中微粒体提取物中的 P450s 形成 O-脱甲基 S-甲草氯，其 NADPH 依赖性比活性大于玉米或 WUS（>20 倍）。通过 CHR 和 SIR 进行的非靶向和靶向液相色谱-质谱分析生成的 S-甲草氯代谢产物与 WUS 不同，其中 O-脱甲基 S-甲草氯和由 CHR 和 SIR 形成的 O-脱甲基 S-甲草氯-谷胱甘肽缀合物的相对丰度更高。总之，我们的结果表明，抗性水花生中 S-甲草氯的代谢涉及协同作用的 I 相和 II 相代谢活性，但最初的 O-脱甲基反应赋予了抗性。
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