Cis-mediated down-regulation of a trypsin gene associated with Bt resistance in cotton bollworm

文献类型： 外文期刊

第一作者： Xiao, Yutao

作者： Xiao, Yutao;Wu, Kongming;Li, Xianchun;Tabashnik, Bruce E.;Oppert, Brenda

作者机构：

期刊名称：SCIENTIFIC REPORTS （ 影响因子：4.379； 五年影响因子：5.133 ）

ISSN： 2045-2322

年卷期： 2014 年 4 卷

页码：

收录情况： SCI

摘要： Transgenic plants producing insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) are useful for pest control, but their efficacy is reduced when pests evolve resistance. Here we examined the mechanism of resistance to Bt toxin Cry1Ac in the laboratory-selected LF5 strain of the cotton bollworm, Helicoverpa armigera. This strain had 110-fold resistance to Cry1Ac protoxin and 39-fold resistance to Cry1Ac activated toxin. Evaluation of five trypsin genes revealed 99% reduced transcription of one trypsin gene (HaTryR) was associated with resistance. Silencing of this gene with RNA interference in susceptible larvae increased their survival on diets containing Cry1Ac. Bioassays of progeny from crosses revealed that resistance to Cry1Ac was genetically linked with HaTryR. We identified mutations in the promoter region of HaTryR in the resistant strain. In transfected insect cell lines, transcription was lower when driven by the resistant promoter compared with the susceptible promoter, implicating cis-mediated down-regulation of HaTryR transcription as a mechanism of resistance. The results suggest that H. armigera can adapt to Bt toxin Cry1Ac by decreased expression of trypsin. Because trypsin activation of protoxin is a critical step in toxicity, transgenic plants with activated toxins rather than protoxins might increase the durability of Bt crops.

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