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【目的】明确与谷胱甘肽S-转移酶(GST)相关联的棉铃虫Helicoverpa armigera(Hübner)对甲氧虫酰肼的抗性分子机制,更有效地开展棉铃虫抗药性的快速监测。【方法】用LC40甲氧虫酰肼处理棉铃虫3龄初幼虫,测定处理前、后抗性种群GST的活性及5种GST基因的表达量变化,并比较一种Delta基因GSTd1的编码区序列。【结果】经测序、比对,抗甲氧虫酰肼种群(R-methoxyfenozide)和同源对照种群(S-methoxyfenozide)GSTd1基因编码区序列相同,表明其编码的酶结构没有发生改变。甲氧虫酰肼处理前,R-methoxyfenozide种群的GST比活力显著高于Smethoxyfenozide种群;而药剂处理后,两种群的GST比活力均降低,但R-methoxyfenozide种群的活性可以快速回升。药剂处理前,R-methoxyfenozide种群的GST基因表达量显著高于S-methoxyfenozide种群。药剂处理对不同抗性种群GST基因表达量的影响差异较大。除了GSTs1,S-methoxyfenozide种群GST基因表达量均降低,其中GSTd2和GSTe2可以缓慢回升。GSTs1表达量在36 h内没有明显变化,但在48 h显著升高。R-methoxyfenozide种群的GST基因表达量均先降低,然后迅速恢复,除GSTe2基因外,R-methoxyfenozide种群的基因初始表达量和药剂处理后的最终表达量均显著高于S-methoxyfenozide种群。【结论】棉铃虫对甲氧虫酰肼的抗性与GST比活力增强有关,而GST比活力的增强主要源于多个GST基因的过量表达。
【Objective】 The molecular mechanism of resistance to methoxyfenozide in Helicoverpa armigera (Hübner) associated with glutathione S-transferase (GST) was clarified to monitor the resistance of H. armigera more effectively. 【Method】 The 3rd-instar larvae of cotton bollworm (Helicoverpa armigera) were treated with methoxyfenozide LC40, the activities of GST and the expression of five GST genes in the resistant population were determined before and after treatment, and the coding region of GSTd1 was compared . 【Result】 The sequence of the coding region of GSTd1 gene of R-methoxyfenozide and S-methoxyfenozide was the same after sequencing and comparison, indicating that the structure of its encoded enzyme did not change. Before methoxyfenozide treatment, the GST specific activity of R-methoxyfenozide population was significantly higher than that of Smethoxyfenozide population. However, the GST specific activity of R-methoxyfenozide population was decreased after treatment with methoxyfenozide, but the activity of R-methoxyfenozide population recovered quickly. Before treatment, the expression level of GST gene in R-methoxyfenozide population was significantly higher than that in S-methoxyfenozide population. The effect of the agent on GST gene expression in different resistant populations varied greatly. Except for GSTs1, GST gene expression in S-methoxyfenozide population was decreased, of which GSTd2 and GSTe2 could slowly rise. GSTs1 expression in 36 h did not change significantly, but significantly increased at 48 h. The expression of GST gene in R-methoxyfenozide population first decreased and then rapidly recovered. The initial gene expression level and the final expression level of R-methoxyfenozide population except GSTe2 gene were significantly higher than that of S-methoxyfenozide population. 【Conclusion】 The resistance of cotton bollworm to methoxyfenozide is related to the enhancement of specific activity of GST, while the enhancement of specific activity of GST is mainly due to the overexpression of multiple GST genes.