Transgenic maize plants expressing dsRNA targeting western corn rootworm (WCR, Diabrotica virgifera virgifera) DvSSJ1 mRNA, a Drosophila snakeskin (ssk) ortholog, show insecticidal activity and significant plant protection from WCR damage. The gene encodes a membrane protein associated with the smooth sepate junction (SSJ) which is required for intestinal barrier function. To understand the active RNA form that leads to the mortality of WCR larvae by DvSSJ1 RNA interference (RNAi), we characterized transgenic plants expressing DvSSJ1 RNA transcripts targeting WCR DvSSJ1 mRNA. The expression of the silencing cassette results in the full-length transcript of 901 nucleotides containing a 210 bp inverted fragment of the DvSSJ1 gene, the formation of a double-stranded RNA (dsRNA) transcript and siRNAs in transgenic plants. Our artificial diet-feeding study indicates that dsRNAs greater than or equal to approximately 60 base-pairs (bp) are required for DvSSJ1 insecticidal activity. Impact of specificity of dsRNA targeting DvSSJ1 mRNA on insecticidal activities was also evaluated in diet bioassay, which showed a single nucleotide mutation can have a significant impact or abolish diet activities against WCR. These results provide insights as to the functional forms of plant-delivered dsRNA for the protection of transgenic maize from WCR feeding damage and information contributing to the risk assessment of transgenic maize expressing insecticidal dsRNA.

转基因玉米植物表达dsRNA针对西部玉米根虫（WCR，叶甲幼芽根叶甲）DvSSJ1表达，一个果蝇蛇皮（SSK）同源物，具有杀虫活性和WCR损害显著植物保护。该基因编码与肠屏障功能所需的平滑分离连接（SSJ）相关的膜蛋白。为了了解导致DvSSJ1 RNA干扰（RNAi）导致WCR幼虫死亡的活性RNA形式，我们鉴定了表达针对WCR DvSSJ1的DvSSJ1 RNA转录本的转基因植物mRNA。沉默盒的表达导致包含DvSSJ1基因的210 bp反向片段的901个核苷酸的全长转录本，在转基因植物中形成双链RNA（dsRNA）转录本和siRNA。我们的人工饮食喂养研究表明，DvSSJ1杀虫活性需要大于或等于约60个碱基对（bp）的dsRNA。靶向DvSSJ1的dsRNA特异性的影响在饮食生物测定法中还评估了mRNA对杀虫活性的影响，结果表明单核苷酸突变可对WCR产生显着影响或取消饮食活动。这些结果提供了关于植物递送的dsRNA用于保护转基因玉米免受WCR饲喂损害的功能形式的见识，以及有助于表达表达杀虫dsRNA的转基因玉米的风险评估的信息。