Cry protein toxins produced by Bacillus thuringiensis (Bt) are now widely used in sprays and transgenic crops to control insect pests. Most recently, ATP-binding cassette transporter proteins (ABC transporter), including ABCC2, ABCC3, ABCG1, ABCA2 and ABCB1, were reported as putative receptors for different Cry toxins. However, little is known about the regulatory mechanism involved in the expression of these ABC transporter genes. In the present study, a conserved target site of miR-998-3p was identified from the coding sequence (CDS) of ABCC2 in diverse lepidopteran insects. Luciferase reporter assays demonstrated that miR-998-3p could bind to the CDS of ABCC2 and down-regulate its expression through a conserved site and several non-conserved sites in three representative lepidopteran pests, including Helicoverpa armigera, Spodoptera exigua and Plutella xylostella. Injection of miR-998-3p agomir significantly reduced the abundance of ABCC2, accompanied by increased tolerance to Cry1Ac toxin in H. armigera, S. exigua and P. xylostella (Cry-S) larvae, while injection of miR-998-3p antagomir increased the abundance of ABCC2 dramatically, and thereby reduced the Cry1Ac resistance in a Cry1Ac resistant population of P. xylostella (GX-R). These results give a better understanding of the mechanisms of post-transcriptional regulation of ABCC2, and will be helpful for further studies on the role of miRNAs in the regulation of Cry1Ac resistance in lepidopteran pests.

中文翻译：

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MicroRNA-998-3p通过靶向鳞翅目昆虫中的ABCC2来增强Cry1Ac抗性。

苏云金芽孢杆菌（Btillus thuringiensis）（Bt）产生的Cry蛋白毒素现已广泛用于喷雾剂和转基因作物中，以控制害虫。最近，据报道，包括ABCC2，ABCC3，ABCG1，ABCA2和ABCB1在内的ATP结合盒转运蛋白（ABC转运蛋白）是不同Cry毒素的推定受体。但是，关于这些ABC转运蛋白基因的表达所涉及的调节机制知之甚少。在本研究中，从各种鳞翅目昆虫的ABCC2的编码序列（CDS）中确定了miR-998-3p的保守靶位点。萤光素酶报告基因检测表明，miR-998-3p可以与ABCC2的CDS结合，并通过三个代表性鳞翅目害虫（包括棉铃虫）中的一个保守位点和几个非保守位点下调其表达。斜纹夜蛾和小菜蛾。注射miR-998-3pagomir可以显着降低ABCC2的丰度，同时增加对棉铃虫，S。exigua和X.ostostella（Cry-S）幼虫对Cry1Ac毒素的耐受性，而注射miR-998-3p antagomir大大增加了ABCC2的丰度，从而降低了小菜蛾（GX-R）对Cry1Ac的抗性群体中对Cry1Ac的抗性。这些结果使人们对ABCC2的转录后调控机制有了更好的了解，并将有助于进一步研究miRNA在鳞翅目害虫中对Cry1Ac抗性的调控中的作用。而注射miR-998-3p antagomir则显着增加了ABCC2的丰度，从而降低了小菜蛾（CX1R）的Cry1Ac耐药人群的Cry1Ac耐药性。这些结果使人们对ABCC2的转录后调控机制有了更好的了解，并将有助于进一步研究miRNA在鳞翅目害虫中对Cry1Ac抗性的调控中的作用。而注射miR-998-3p antagomir则显着增加了ABCC2的丰度，从而降低了小菜蛾（CX1R）的Cry1Ac耐药人群的Cry1Ac耐药性。这些结果使人们对ABCC2的转录后调控机制有了更好的了解，并将有助于进一步研究miRNA在鳞翅目害虫中对Cry1Ac抗性的调控中的作用。