Division of Plant Sciences, University of Missouri, Columbia, MO, USA.
USDA-ARS, Columbia, MO, Columbia, MO, USA.
Sci Rep. 2019 Mar 20;9(1):4896. doi: 10.1038/s41598-019-41067-7.
Diabrotica virgifera virgifera LeConte, the western corn rootworm (WCR) is one of the most destructive pests in the U.S. Corn Belt. Transgenic maize lines expressing various Cry toxins from Bacillus thuringiensis have been adopted as a management strategy. However, resistance to many Bt toxins has occurred. To investigate the mechanisms of Bt resistance we carried out RNA-seq using Illumina sequencing technology on resistant, eCry3.1Ab-selected and susceptible, unselected, whole WCR neonates which fed on seedling maize with and without eCry3.1Ab for 12 and 24 hours. In a parallel experiment RNA-seq experiments were conducted when only the midgut of neonate WCR was evaluated from the same treatments. After de novo transcriptome assembly we identified differentially expressed genes (DEGs). Results from the assemblies and annotation indicate that WCR neonates from the eCry3.1Ab-selected resistant colony expressed a small number of up and down-regulated genes following Bt intoxication. In contrast, unselected susceptible WCR neonates expressed a large number of up and down-regulated transcripts in response to intoxication. Annotation and pathway analysis of DEGs between susceptible and resistant whole WCR and their midgut tissue revealed genes associated with cell membrane, immune response, detoxification, and potential Bt receptors which are likely related to eCry3.1Ab resistance. This research provides a framework to study the toxicology of Bt toxins and mechanism of resistance in WCR, an economically important coleopteran pest species.
玉米根萤叶甲（Diabrotica virgifera virgifera LeConte），又称西部玉米根虫，是美国玉米带中最具破坏性的害虫之一。转 Bt 基因玉米的应用是其防治策略之一，这些玉米表达了来自苏云金芽孢杆菌的各种 Cry 毒素。然而，玉米根萤叶甲对许多 Bt 毒素已经产生了抗性。为了研究 Bt 抗性的机制，我们使用 Illumina 测序技术对来自抗性、经 eCry3.1Ab 选择的和敏感、未经选择的整个玉米根萤叶甲幼虫进行了 RNA-seq 分析，这些幼虫在喂食含或不含 eCry3.1Ab 的玉米幼苗 12 小时和 24 小时后进行了研究。在一个平行实验中，当仅评价来自相同处理的幼虫的中肠时，我们进行了 RNA-seq 实验。在从头组装转录组后，我们鉴定了差异表达基因（DEGs）。组装和注释的结果表明，来自 eCry3.1Ab 选择的抗性品系的玉米根萤叶甲幼虫在 Bt 中毒后表达了少数上调和下调的基因。相比之下，敏感的玉米根萤叶甲幼虫在受到中毒后表达了大量的上调和下调的转录本。对敏感和抗性的整个玉米根萤叶甲及其中肠组织的 DEGs 的注释和途径分析揭示了与细胞膜、免疫反应、解毒和潜在的 Bt 受体相关的基因，这些基因可能与 eCry3.1Ab 抗性有关。这项研究为研究 Bt 毒素的毒理学和玉米根萤叶甲的抗性机制提供了一个框架，玉米根萤叶甲是一种具有经济重要性的鞘翅目害虫。
