The diamondback moth (DBM), Plutella xylostella (L.), has evolved resistance to multiple insecticides including Bacillus thuringiensis (Bt). ATP-binding cassette (ABC) transporters are a class of transmembrane protein families, involved in multiple physiological processes and pesticide resistances in insects. However, the role and regulatory mechanism of ABC transporter in mediating the response to Bt Cry1Ac toxin remain unclear. Here, we characterized a MAPK signaling pathway-enriched ABCG subfamily gene PxABCG20 from DBM, and found it was differentially expressed in the Cry1Ac-resistant and Cry1Ac-susceptible strains. RNAi knockdown of PxABCG20 increased the tolerance of DBM to Cry1Ac protoxin. To explore the regulatory mechanism of PxABCG20 expression, we predicted the potential miRNAs targeting PxABCG20 using two target prediction algorithms. Luciferase reporter assay confirmed that novel-miR-310 was able to down-regulate PxABCG20 expression in HEK293T cells. Furthermore, injection of novel-miR-310 agomir markedly inhibited PxABCG20 expression, resulting in increased tolerance to Cry1Ac protoxin in susceptible strain, while injection of novel-miR-310 antagomir markedly induced the expression of PxABCG20, leading to decreased tolerance to Cry1Ac protoxin. Our work provides theoretical basis for exploring novel targets for the DBM response to Cry1Ac toxin and expands the understanding of miRNA role in mediating the susceptibility of insect pest to Cry1Ac toxin.

小菜蛾 (DBM)小菜蛾(L.) 已进化出对多种杀虫剂的抗性，包括苏云金芽孢杆菌(Bt)。ATP结合盒（ABC）转运蛋白是一类跨膜蛋白家族，参与昆虫的多种生理过程和农药抗性。然而，ABC转运蛋白在介导Bt Cry1Ac毒素反应中的作用和调控机制仍不清楚。在这里，我们从 DBM 中表征了一个富含 MAPK 信号通路的 ABCG 亚家族基因PxABCG20，发现它在 Cry1Ac 抗性和 Cry1Ac 易感菌株中差异表达。PxABCG20的 RNAi 敲低增加 DBM 对 Cry1Ac 原毒素的耐受性。为了探索PxABCG20表达的调控机制，我们使用两种目标预测算法预测了靶向PxABCG20的潜在 miRNA 。萤光素酶报告基因检测证实新型 miR-310 能够下调HEK293T 细胞中PxABCG20的表达。此外，注射novel-miR-310 agomir显着抑制PxABCG20的表达，导致敏感菌株对Cry1Ac原毒素的耐受性增加，而注射novel-miR-310 antagomir显着诱导PxABCG20的表达，导致对 Cry1Ac 原毒素的耐受性降低。我们的工作为探索 DBM 对 Cry1Ac 毒素反应的新靶点提供了理论基础，并扩大了对 miRNA 在介导害虫对 Cry1Ac 毒素易感性中的作用的理解。