RNAi-Mediated Silencing of Putative Halloween Gene Phantom Affects the Performance of Rice Striped Stem Borer, Chilo suppressalis

Abstract

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 Cs-Phm in a major insect pest in agriculture, the rice striped stem borer, Chilo suppressalis (C. suppressalis). A full-length transcript of Cs-Phm was amplified with an open reading frame (ORF) of 478 amino acids through 5′ and 3′ RACE. Cs-Phm 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 Cs-Phm 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 Cs-Phm is functionally conserved in C. suppressalis and encodes functional CYP that contributes to the biogenesis of 20E.

Lethal, Sub-Lethal and Trans-Generational Effects of Chlorantraniliprole on Biological Parameters, Demographic Traits, and Fitness Costs of Spodoptera frugiperda (Lepidoptera: Noctuidae)

“…Various control measures for the management of arthropod pests are now being developed by researchers. These tactics are aimed to be less harmful to humans, the environment, and predators [ 54 , 55 , 56 , 57 , 58 ]. However, synthetic insecticides are still among the best options available.…”

Comparative transcriptomics uncovers apoptosis in brain impairment in newly pupated honeybee worker under cold stress

“…Silencing the CYP306A1 gene expression in third instar larvae of Chilo suppressalis resulted in a signi cant decrease in pupation rate and pupal weight [56]. The CYP307B1 enzyme is also important for ecdysone biosynthesis [57,58], catalyzing the conversion of 2-deoxydecanone to 3-deoxydecanone [59]. In this study, the downregulated genes CYP306A1 (phm) and CYP307B1 (spookiest) were enriched in the KEGG signalling pathway of insect hormone biosynthesis (P = 0.027 Q = 0.484).…”

Silenciamento gênico de >i<Diatraea saccharalis>/i< utilizando a técnica de RNA de interferência (RNAi)

“…Os níveis de 20E de ninfas tratadas com dsSPO foram geralmente baixos, sugerindo que a perturbação dos níveis de 20E causou as anormalidades de desenvolvimento citadas (Sugahara et al, 2017). A injeção de RNA de fita dupla referente ao gene phantom no estágio larval de Chilo suppressalis diminuiu eficientemente seu nível de expressão (Shahzad et al, 2022). O grupo de insetos tratados com dsRNA mostrou concentrações de ecdisteróides significativamente diminuídos, ocasionado atraso no desenvolvimento larval e maior Figura 12.…”

“…mortalidade larval (Shahzad et al, 2022). Resultados semelhantes foram documentados para outras espécies de lepidópteros como Bombyx mori e Plutella xylostella, demonstrando que a regulação negativa de genes Halloween pode resultar em maior duração do desenvolvimento, menor pupação, defeitos fenotípicos, bem como mortalidade (Peng et al, 2019;Niwa et al, 2010).…”