Shahzad Muhammad Faisal, Idrees Atif, Afzal Ayesha, Iqbal Jamshaid, Qadir Ziyad Abdul, Khan Azhar Abbas, Ullah Ayat, Li Jun
Department of Entomology, Faculty of Agriculture, Gomal University, Dera Ismail Khan 29220, Pakistan.
College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
Insects. 2022 Aug 15;13(8):731. doi: 10.3390/insects13080731.
The physiological and biochemical characterization of the "Halloween" genes has fundamental importance in the biosynthesis pathway of ecdysteroids. These genes were found to catalyze the final phases of ecdysteroid biosynthesis from dietary cholesterol to the molting hormone 20-hydroxyecdysone. We report the characterization of the in a major insect pest in agriculture, the rice striped stem borer, (). A full-length transcript of was amplified with an open reading frame (ORF) of 478 amino acids through 5' and 3' RACE. shows five insect-conserved P450 motifs: Helix-C, Helix-I, Helix-K, PERF, and heme-binding motifs. Phylogenetic analysis clearly shows high similarity to Lepidoptera and evolutionary conservation in insects. The relative spatial and temporal transcript profile shows that is highly expressed in the prothoracic glands and appears throughout the larval development, but with low expression at the start of the larval instar. It seems to peak in 3-4 days and decreases again before the larvae molt. Double-stranded RNA (dsRNA) injection of Cs-Phm at the larval stage efficiently knocked down the target gene and decreased its expression level. The dsRNA-treated group showed significantly decreased ecdysteroid titers, which leads to delayed larval development and higher larval mortality. Negative effects of larval development were rescued by treating 20E in the dsRNA-treated group. Thus, in conclusion, our results suggest that is functionally conserved in and encodes functional CYP that contributes to the biogenesis of 20E.
“万圣节”基因的生理生化特性在蜕皮甾类生物合成途径中具有重要意义。这些基因被发现催化从膳食胆固醇到蜕皮激素20-羟基蜕皮酮的蜕皮甾类生物合成的最后阶段。我们报道了农业主要害虫水稻二化螟（Chilo suppressalis）中Cs-Phm的特性。通过5'和3' RACE扩增出一个具有478个氨基酸开放阅读框（ORF）的Cs-Phm全长转录本。Cs-Phm显示出五个昆虫保守的细胞色素P450基序：螺旋-C、螺旋-I、螺旋-K、PERF和血红素结合基序。系统发育分析清楚地表明其与鳞翅目具有高度相似性且在昆虫中具有进化保守性。相对时空转录谱显示Cs-Phm在前胸腺中高度表达且在整个幼虫发育过程中均有出现，但在幼虫龄期开始时表达较低。它似乎在3-4天达到峰值并在幼虫蜕皮前再次下降。在幼虫阶段注射双链RNA（dsRNA）的Cs-Phm能有效敲低靶基因并降低其表达水平。dsRNA处理组显示蜕皮甾类滴度显著降低，这导致幼虫发育延迟和幼虫死亡率升高。通过在dsRNA处理组中处理20E可挽救幼虫发育的负面影响。因此，总之，我们的结果表明Cs-Phm在水稻二化螟中功能保守，编码有助于20E生物合成的功能性细胞色素P450。
