Department of Genetics, University of Delhi - South Campus, Benito Juarez Road, New Delhi 110021, India.
J Biosci. 2020;45.
The cotton bollworm, , is a highly polyphagous pest, causing enormous losses to various economically important crops. The identification and functional validation of target genes of a pest is a prerequisite to combat pest via host-mediated RNA interference (RNAi). In the present study, six hormonal biosynthesis genes of were chosen and evaluated by feeding insect larvae with dsRNAs corresponding to each target gene, viz., juvenile hormone acid methyltransferase , prothoracicotropic hormone (HaPTTH), pheromone biosynthesis-activating peptide , molt regulating transcription factor (HaHR3), activated protein 4 and eclosion hormone precursor (HaEHP). The loss of function phenotypes for these hormonal genes were observed by releasing second instar larvae on to artificial diet containing target gene-specific dsRNAs. Ingestion of dsRNAs resulted in mortality ranging from 60% to 90%, reduced larval weight, phenotypic deformities and delayed pupation. The quantitative real-time PCR (qRT-PCR) analysis showed that the target gene transcript levels were decreased drastically (31% to 77%) as compared to control or unrelated control (-dsRNA), and correlated well with the mortality and developmental defects of larvae. Also, a comparison of the silencing efficacy of un-diced long -dsRNAwith RNase III diced -dsRNA (siRNAs) revealed that long dsRNAs were more efficient in silencing the target gene. These results indicated that the hormonal biosynthesis genes have varied sensitivity towards RNAi and could be the vital targets for insect resistance in crop plants like cotton which are infested by .
棉铃虫是一种高度多食性害虫，对各种重要经济作物造成巨大损失。鉴定和功能验证害虫的靶标基因是通过宿主介导的 RNA 干扰（RNAi）防治害虫的前提。在本研究中，选择了棉铃虫的 6 个激素生物合成基因，并通过用对应于每个靶基因的 dsRNA 喂养幼虫来评估这些基因，即保幼激素酸甲基转移酶、前胸腺激素（HaPTTH）、信息素生物合成激活肽、蜕皮激素调节转录因子（HaHR3）、激活蛋白 4 和蜕皮激素前体（HaEHP）。通过将第二龄幼虫释放到含有靶基因特异性 dsRNA 的人工饲料上，观察到这些激素基因的功能丧失表型。dsRNA 的摄入导致死亡率从 60%到 90%不等，幼虫体重减轻，出现表型畸形，并延迟化蛹。定量实时 PCR（qRT-PCR）分析显示，与对照或不相关的对照（-dsRNA）相比，靶基因的转录水平急剧下降（31%至 77%），与幼虫的死亡率和发育缺陷密切相关。此外，未切割的长 dsRNA 与 RNase III 切割的 dsRNA（siRNAs）的沉默效果比较表明，长 dsRNA 更有效地沉默靶基因。这些结果表明，激素生物合成基因对 RNAi 的敏感性不同，可能是棉花等受侵害的作物中昆虫抗性的重要靶标。
