Anhui Province Key Laboratory of Crop Integrated Pest Management, Anhui Province Engineering Laboratory for Green Pesticide Development and Application, School of Plant Protection, Anhui Agricultural University, Hefei, 230036, China.
Anhui Province Key Laboratory of Crop Integrated Pest Management, Anhui Province Engineering Laboratory for Green Pesticide Development and Application, School of Plant Protection, Anhui Agricultural University, Hefei, 230036, China.
Pestic Biochem Physiol. 2023 Feb;190:105321. doi: 10.1016/j.pestbp.2022.105321. Epub 2022 Dec 20.
As a multigene superfamily of Phase II detoxification enzymes, uridine diphosphate (UDP)-glycosyltransferases (UGTs) play important roles in the metabolism of xenobiotics including insecticides. In this study, 5-nitrouracil, an inhibitor of UGT enzyme activity, effectively increased the toxicity of chlorpyrifos to the chlorpyrifos-resistant strain of Nilaparvata lugens, one of the most resistant rice pests. The enzyme content of UGT in the resistant strain was significantly higher than that in the susceptible strain. Among 20 identified UGT genes, UGT386H2, UGT386J2, UGT386N2 and UGT386P1 were found significantly overexpressed in the resistant strain and can be effectively induced by chlorpyrifos. These four UGT genes were most highly expressed in the midgut and/or fat body, two main insect detoxification tissues. Amino acid sequence alignments revealed that these four UGTs contained a variable N-terminal substrate-binding domain and a conserved C-terminal sugar donor-binding domain. Furthermore, homology modeling and molecular docking analyses showed that these UGTs could stably bind to chlorpyrifos and chlorpyrifos oxon, with the binding free energies from -19.4 to -110.62 kcal mol. Knockdown of UGT386H2 or UGT386P1 by RNA interference dramatically increased the susceptibility of the resistant strain to chlorpyrifos. These findings suggest that overexpression of these two UGT genes contributes to chlorpyrifos resistance in N. lugens.
作为 II 相解毒酶的一个多基因超家族，尿苷二磷酸（UDP）-糖基转移酶（UGTs）在包括杀虫剂在内的外源化学物的代谢中发挥着重要作用。在本研究中，5-硝基尿嘧啶，一种 UGT 酶活性抑制剂，能有效提高毒死蜱对褐飞虱抗药性品系的毒性，褐飞虱是最具抗药性的水稻害虫之一。抗性品系的 UGT 酶含量明显高于敏感品系。在鉴定出的 20 个 UGT 基因中，UGT386H2、UGT386J2、UGT386N2 和 UGT386P1 在抗性品系中显著过表达，并且可以被毒死蜱有效诱导。这四个 UGT 基因在中肠和/或脂肪体中表达最高，这是两个主要的昆虫解毒组织。氨基酸序列比对表明，这四个 UGT 含有可变的 N 端底物结合域和保守的 C 端糖供体结合域。此外，同源建模和分子对接分析表明，这些 UGT 可以稳定地结合到毒死蜱和毒死蜱氧肟酸上，结合自由能从-19.4 到-110.62 kcal/mol。通过 RNA 干扰敲低 UGT386H2 或 UGT386P1 可显著增加抗性品系对毒死蜱的敏感性。这些发现表明，这两个 UGT 基因的过表达有助于褐飞虱对毒死蜱的抗性。
