Xu Q-Y, Meng Q-W, Deng P, Fu K-Y, Guo W-C, Li G-Q
Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
Department of Plant Protection, Xinjiang Academy of Agricultural Sciences, Urumqi 830091, China.
Bull Entomol Res. 2019 Oct;109(5):659-668. doi: 10.1017/S0007485318001050. Epub 2019 Feb 1.
Dietary delivery of bacterially expressed double-stranded RNA (dsRNA) has a great potential for management of Leptinotarsa decemlineata. An important first step is to discover possible RNA-interference (RNAi)-target genes effective against larvae, especially the old larvae. In the present paper, five putative Broad-Complex (BrC) cDNAs (Z1-Z4, and Z6) were identified in L. decemlineata. The expression of the five LdBrC isoforms was suppressed by juvenile hormone signaling, whereas the transcription was upregulated by 20-hydroxyecdysone signaling at the fourth (final) instar larval stage. Feeding of bacterially expressed dsBrC (derived from a common fragment of the five LdBrC variants) in the third- and fourth-instar larvae successfully knocked down the target mRNAs. For the fourth-instar LdBrC RNAi hypomorphs, they had a higher larval mortality compared with the controls. Moreover, most dsBrC-fed beetles did not pupate normally. After removal of the apolysed larval cuticle, a miniature adult was found. The adult head, compound eyes, prothorax, mesothorax, metathorax were found on the dorsal view. Distinct adult cuticle pigmentation was seen on the prothorax. The mouthparts, forelegs, midlegs, and hindlegs could be observed on the ventral view of the miniature adults. For the third-instar LdBrC RNAi specimens, around 20% moribund beetles remained as prepupae and finally died. Therefore, LdBrC is among the most attractive candidate genes for RNAi to control the fourth-instar larvae in L. decemlineata.
通过饮食递送细菌表达的双链RNA（dsRNA）在治理马铃薯甲虫方面具有巨大潜力。重要的第一步是发现可能对幼虫尤其是老龄幼虫有效的RNA干扰（RNAi）靶基因。在本文中，在马铃薯甲虫中鉴定出了五个假定的广谱复合体（BrC）cDNA（Z1 - Z4和Z6）。这五种LdBrC亚型的表达受到保幼激素信号的抑制，而在四龄（末龄）幼虫阶段，转录受到20 - 羟基蜕皮激素信号的上调。在三龄和四龄幼虫中喂食细菌表达的dsBrC（源自五个LdBrC变体的共同片段）成功敲低了靶标mRNA。对于四龄LdBrC RNAi低表达型，它们的幼虫死亡率高于对照组。此外，大多数喂食dsBrC的甲虫不能正常化蛹。去除蜕去表皮的幼虫表皮后，发现了一个微型成虫。在背面可以看到成虫的头部、复眼、前胸、中胸、后胸。在前胸上可以看到明显的成虫表皮色素沉着。在微型成虫的腹面可以观察到口器、前腿、中腿和后腿。对于三龄LdBrC RNAi标本，约20%濒死的甲虫保持为预蛹状态并最终死亡。因此，LdBrC是通过RNAi控制马铃薯甲虫四龄幼虫最具吸引力的候选基因之一。
