State Key Laboratory of Wheat and Maize Crop Science/College of Plant Protection, Henan Agricultural University, Zhengzhou, China.
Kaifeng Agricultural Technology Extension Station, Kaifeng, China.
Pest Manag Sci. 2021 Apr;77(4):2142-2150. doi: 10.1002/ps.6243. Epub 2021 Jan 29.
Extensive planting of transgenetic Bacillus thuringiensis crops has driven the evolution of pest resistance to Cry1Ac. Adjustment of cropping structures has promoted further outbreak of Helicoverpa armigera in China. To control this pest, a combination of pyramiding RNA interference (RNAi) and Cry2Ab is considered a promising strategy for countering cross-resistance and enhancing the toxicity of Cry2Ab to cotton bollworm. We explored the possibility of using calcineurin (CAN) as a target RNAi gene, because it is involved in cotton bollworm responses to the toxicity of Cry2Ab.
Cry2Ab treatment led to a significant increase in HaCAN mRNA level and HaCAN activity. Suppression of HaCAN activity due to RNAi-mediated knockdown of HaCAN increased the susceptibility of midgut cells to Cry2Ab. The increase in HaCAN activity shown by heterologous expression of HaCAN reduced the cytotoxicity of Cry2Ab to Sf9 cells. Moreover, ingestion of HaCAN-specific inhibitor FK506 increased the toxicity of Cry2Ab in larvae. Interestingly, HaCAN does not function as a Cry2Ab direct binding protein that participates in Cry2Ab toxicity.
The results in this study provide evidence that suppression of HaCAN not only affected the development of the cotton bollworm, but also enhanced the toxicity of Cry2Ab to the pest. HaCAN is therefore an important candidate gene in cotton bollworm that can be targeted for pest control when the pest infests RNAi+Cry2Ab crops. Meanwhile, the mechanism of action of HaCAN in Cry2Ab toxicity suggested that protein dephosphorylation was involved. © 2020 Society of Chemical Industry.
转 Bt 基因作物的广泛种植促使害虫对 Cry1Ac 的抗性进化。种植结构的调整进一步促进了棉铃虫在中国的爆发。为了控制这种害虫，将 RNA 干扰（RNAi）与 Cry2Ab 叠加被认为是一种有前途的策略，可以克服抗药性并增强 Cry2Ab 对棉铃虫的毒性。我们探讨了钙调神经磷酸酶（CAN）作为 RNAi 靶基因的可能性，因为它参与了棉铃虫对 Cry2Ab 毒性的反应。
Cry2Ab 处理导致 HaCAN mRNA 水平和 HaCAN 活性显著增加。由于 HaCAN 的 RNAi 介导的敲低导致 HaCAN 活性抑制，中肠细胞对 Cry2Ab 的敏感性增加。通过异源表达 HaCAN 增加 HaCAN 活性，降低了 Cry2Ab 对 Sf9 细胞的细胞毒性。此外，摄入 HaCAN 特异性抑制剂 FK506 增加了幼虫中 Cry2Ab 的毒性。有趣的是，HaCAN 不作为参与 Cry2Ab 毒性的 Cry2Ab 直接结合蛋白发挥作用。
本研究结果提供了证据，表明抑制 HaCAN 不仅影响棉铃虫的发育，而且增强了 Cry2Ab 对害虫的毒性。因此，HaCAN 是棉铃虫的一个重要候选基因，当害虫侵害 RNAi+Cry2Ab 作物时，可以将其作为害虫防治的靶标。同时，HaCAN 在 Cry2Ab 毒性中的作用机制表明涉及蛋白质去磷酸化。 © 2020 英国化学学会。
