Global transcriptome profiling and functional analysis reveal that tissue-specific constitutive overexpression of cytochrome P450s confers tolerance to imidacloprid in palm weevils in date palm fields

Abstract

Background Cytochrome P450-dependent monooxygenases (P450s), constituting one of the largest and oldest gene superfamilies found in many organisms from bacteria to humans, play a vital role in the detoxification and inactivation of endogenous toxic compounds. The use of various insecticides has increased over the last two decades, and insects have developed resistance to most of these compounds through the detoxifying function of P450s. In this study, we focused on the red palm weevil (RPW), Rhynchophorus ferrugineus, the most devastating pest of palm trees worldwide, and demonstrated through functional analysis that upregulation of P450 gene expression has evolved as an adaptation to insecticide stress arising from exposure to the neonicotinoid-class systematic insecticide imidacloprid. Results Based on the RPW global transcriptome analysis, we identified 101 putative P450 genes, including 77 likely encoding protein coding genes with ubiquitous expression. A phylogenetic analysis revealed extensive functional and species-specific diversification of RPW P450s, indicating that multiple CYPs actively participated in the detoxification process. We identified highly conserved paralogs of insect P450s that likely play a role in the development of resistance to imidacloprid: Drosophila Cyp6g1 ( CYP6345J1 ) and Bemisia tabaci CYP4C64 ( CYP4LE1 ). We performed a toxicity bioassay and evaluated the induction of P450s, followed by the identification of overexpressed P450s, including CYP9Z82 , CYP6fra5, CYP6NR1 , CYP6345J1 and CYP4BD4 , which confer cross-resistance to imidacloprid. In addition, under imidacloprid insecticide stress in a date palm field, we observed increased expression of various P450 genes, with CYP9Z82 , CYP4BD4, CYP6NR1 and CYP6345J1 being the most upregulated detoxification genes in RPWs. Expression profiling and cluster analysis revealed P450 genes with multiple patterns of induction and differential expression. Furthermore, we used RNA interference to knock down the overexpressed P450s, after which a toxicity bioassay and quantitative expression analysis revealed likely candidates involved in metabolic resistance against imidacloprid in RPW. Ingestion of double-stranded RNA (dsRNA) successfully knocked down the expression of CYP9Z82, CYP6NR1 and CYP345J1 and demonstrated that silencing of CYP345J1 and CYP6NR1 significantly decreased the survival rate of adult RPWs treated with imidacloprid, indicating that overexpression of these two P450s may play an important role in developing tolerance to imidacloprid in a date palm field. ...

Haplotype-resolved genome assembly enables gene discovery in the red palm weevil Rhynchophorus ferrugineus

“…Second, we compared our BRAKER genome annotation against curated sets of RPW genes that are potentially relevant for pest mitigation strategies 9, 11, 48 . Transcript identifiers for chemosensory genes were obtained from Antony et al 9 and parsed from their transcriptome assembly (GDKA01000000).…”

“…Transcript identifiers for chemosensory genes were obtained from Antony et al 9 and parsed from their transcriptome assembly (GDKA01000000). Transcripts for cytochrome P450 monooxygenases were obtained from Antony et al 48 . Transcripts for neuropeptides and their G-protein coupled receptors (GPCRs) were obtained from Zhang et al 11 (MK751489–MK751534, MK751535–MK751576).…”

High-throughput profiling of diapause regulated genes from Trichogramma dendrolimi, an important egg parasitoid

“…In fact, many studies have used RNAsequencing (RNA-Seq) to solve a wide variety of problems. Some studies focused on insect resistance to insecticide [30][31][32][33] , some on insect adaptability to extreme environments [34,35] , and others on selected genes, like chemosensory genes [36] . But there have been few studies on insect diapause using RNA-Seq.…”

High-throughput profiling of diapause regulated genes from Trichogramma dendrolimi, an important egg parasitoid

“…In fact, many studies have used RNA-sequencing (RNA-Seq) to solve a wide variety of problems. Some studies focused on insect resistance to insecticide [28][29][30][31] , some on insect adaptability to extreme environments [32,33] , and others on selected genes, like chemosensory genes [34] . But there have been few studies on insect diapause using RNA-Seq.…”