Longping Branch, Graduate School of Hunan University, Changsha, China.
Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China.
Appl Environ Microbiol. 2021 Jun 11;87(13):e0046621. doi: 10.1128/AEM.00466-21.
Deciphering the molecular mechanisms underlying insect resistance to Cry toxins produced by Bacillus thuringiensis (Bt) is pivotal for the sustainable utilization of Bt biopesticides and transgenic Bt crops. Previously, we identified that mitogen-activated protein kinase (MAPK)-mediated reduced expression of the gene is associated with Bt Cry1Ac resistance in the diamondback moth, Plutella xylostella (L.). However, the underlying transcriptional regulation mechanism remains enigmatic. Here, the promoter in Cry1Ac-susceptible and Cry1Ac-resistant strains was cloned and analyzed and found to contain a putative Jun binding site (JBS). A dual-luciferase reporter assay and yeast one-hybrid assay demonstrated that the transcription factor PxJun repressed expression by interacting with this JBS. The expression levels of were increased in the midguts of all resistant strains compared to the susceptible strain. Silencing of expression significantly elevated expression and Cry1Ac susceptibility in the resistant NIL-R strain, and silencing of expression decreased expression and also increased expression. These results indicate that MAPK-activated PxJun suppresses expression to confer Cry1Ac resistance in , deepening our understanding of the transcriptional regulation of midgut Cry receptor genes and the molecular basis of insect resistance to Bt Cry toxins. The transcriptional regulation mechanisms underlying reduced expression of Bt toxin receptor genes in Bt-resistant insects remain elusive. This study unveils that a transcription factor PxJun activated by the MAPK signaling pathway represses expression and confers Cry1Ac resistance in . Our results provide new insights into the transcriptional regulation mechanisms of midgut Cry receptor genes and deepen our understanding of the molecular basis of insect resistance to Bt Cry toxins. To our knowledge, this study identified the first transcription factor that can be involved in the transcriptional regulation mechanisms of midgut Cry receptor genes in Bt-resistant insects.
解析昆虫对苏云金芽孢杆菌（Bt）产生的 Cry 毒素产生抗性的分子机制对于可持续利用 Bt 生物农药和转 Bt 作物至关重要。此前，我们发现丝裂原活化蛋白激酶（MAPK）介导的 基因表达降低与小菜蛾对 Bt Cry1Ac 的抗性有关。然而，其潜在的转录调控机制仍然难以捉摸。在这里，我们克隆并分析了 Cry1Ac 敏感和 Cry1Ac 抗性 菌株中的 启动子，发现其含有一个假定的 Jun 结合位点（JBS）。双荧光素酶报告基因检测和酵母单杂交实验表明，转录因子 PxJun 通过与该 JBS 相互作用来抑制 基因的表达。与敏感株相比，所有抗性株的中肠中 的表达水平均升高。在抗性 NIL-R 株中沉默 表达水平显著提高了 表达和 Cry1Ac 敏感性，而沉默 表达水平降低了 表达水平，同时也提高了 表达水平。这些结果表明，MAPK 激活的 PxJun 抑制 表达从而赋予小菜蛾对 Cry1Ac 的抗性，加深了我们对中肠 Cry 受体基因转录调控和昆虫对 Bt Cry 毒素抗性的分子基础的理解。Bt 抗性昆虫中 Bt 毒素受体基因表达降低的转录调控机制仍不清楚。本研究揭示了一种由 MAPK 信号通路激活的转录因子 PxJun 抑制 表达并赋予小菜蛾对 Cry1Ac 的抗性。我们的研究结果为中肠 Cry 受体基因的转录调控机制提供了新的见解，并加深了我们对昆虫对 Bt Cry 毒素抗性的分子基础的理解。据我们所知，本研究首次鉴定出一种可以参与 Bt 抗性昆虫中肠 Cry 受体基因转录调控机制的转录因子。
