Abstract:Cotton plants produce gossypol as a major secondary metabolite to resist insect herbivores and pathogens. Helicoverpa armigera may employ multigene families of detoxification enzymes to deal with this metabolite. So far, the strength of the transcriptional response to gossypol detoxification in the cotton bollworms remains poorly understood. Here, we investigated the genomewide transcriptional changes that occur in cotton bollworm larvae after one generation feeding on various host plants (cotton, corn, soybea… Show more
“…P450s, GSTs, UGTs, and CarEs are four insect detoxification enzyme superfamilies that metabolize both phytochemicals and synthetic insecticides. , Cheng et al sequenced the genome of S. litura and investigated the transcriptomic changes after exposure to xanthotoxin, ricin or imidacloprid by using RNA-Seq . The transcriptomic results showed that a fairly large number of detoxification genes were induced when larvae were exposed to xanthotoxin and that a great amount of them are also upregulated by flavone. , This indicates that the metabolic detoxification mechanisms of λ-cyhalothrin tolerance after xanthotoxin ingestion can be inferred from the study of flavone-induced detoxification genes.…”
Section: Discussionmentioning
confidence: 99%
“…The induction of metabolic detoxification enzyme systems following exposure to phytochemicals has helped herbivorous insects to detoxify synthetic insecticides . Cytochrome P450 monooxygenases (P450s), uridine diphosphate (UDP)-glycosyltransferases (UGTs), carboxylesterases (CarEs), and glutathione S-transferases (GSTs) are among the detoxification enzymes used by insects in response to both phytochemicals and insecticides. , Phytochemical-inducible detoxification enzymes with “broad-spectrum” substrates can help herbivorous insects tolerate synthetic insecticides. The detoxification genes are induced after exposure to phytochemicals or even constitutively overexpressed after host plant adaptation.…”
Adaptation
to phytochemicals in herbivorous insects can influence
tolerance to insecticides. However, it is unclear how insects use
phytochemicals as cues to activate their metabolic detoxification
systems. In this study, we found that dietary exposure to xanthotoxin
enhanced tolerance of Spodoptera litura larvae to
λ-cyhalothrin. Xanthotoxin ingestion significantly elevated
the mRNA levels of 35 detoxification genes as well as the transcription
factors Cap ‘n’ collar isoform-C (CncC) and its binding factor small muscle aponeurosis fibromatosis isoform-K
(MafK). Additionally, xanthotoxin exposure increased
the levels of reactive oxygen species (ROS), while ROS inhibitor N-acetylcysteine
(NAC) treatment blocked xanthotoxin-induced expression of CncC, MafK, and detoxification genes and
also prevented xanthotoxin-enhanced larval tolerance to λ-cyhalothrin.
The 20-hydroxyecdysone (20E) signaling pathway was effectively activated
by xanthotoxin, while blocking of 20E signaling transduction prevented
xanthotoxin-enhanced larval tolerance to λ-cyhalothrin. Application
of 20E induced the expression of multiple xanthotoxin-induced detoxification
genes and enhanced λ-cyhalothrin tolerance in S. litura. NAC treatment blocked xanthotoxin-induced 20E synthesis, while
the CncC agonist curcumin activated the 20E signaling pathway. These
results indicate that the ROS/CncC pathway controls the induction
of metabolic detoxification upon exposure to xanthotoxin, at least
in part, through its regulation of the 20E signaling pathway.
“…P450s, GSTs, UGTs, and CarEs are four insect detoxification enzyme superfamilies that metabolize both phytochemicals and synthetic insecticides. , Cheng et al sequenced the genome of S. litura and investigated the transcriptomic changes after exposure to xanthotoxin, ricin or imidacloprid by using RNA-Seq . The transcriptomic results showed that a fairly large number of detoxification genes were induced when larvae were exposed to xanthotoxin and that a great amount of them are also upregulated by flavone. , This indicates that the metabolic detoxification mechanisms of λ-cyhalothrin tolerance after xanthotoxin ingestion can be inferred from the study of flavone-induced detoxification genes.…”
Section: Discussionmentioning
confidence: 99%
“…The induction of metabolic detoxification enzyme systems following exposure to phytochemicals has helped herbivorous insects to detoxify synthetic insecticides . Cytochrome P450 monooxygenases (P450s), uridine diphosphate (UDP)-glycosyltransferases (UGTs), carboxylesterases (CarEs), and glutathione S-transferases (GSTs) are among the detoxification enzymes used by insects in response to both phytochemicals and insecticides. , Phytochemical-inducible detoxification enzymes with “broad-spectrum” substrates can help herbivorous insects tolerate synthetic insecticides. The detoxification genes are induced after exposure to phytochemicals or even constitutively overexpressed after host plant adaptation.…”
Adaptation
to phytochemicals in herbivorous insects can influence
tolerance to insecticides. However, it is unclear how insects use
phytochemicals as cues to activate their metabolic detoxification
systems. In this study, we found that dietary exposure to xanthotoxin
enhanced tolerance of Spodoptera litura larvae to
λ-cyhalothrin. Xanthotoxin ingestion significantly elevated
the mRNA levels of 35 detoxification genes as well as the transcription
factors Cap ‘n’ collar isoform-C (CncC) and its binding factor small muscle aponeurosis fibromatosis isoform-K
(MafK). Additionally, xanthotoxin exposure increased
the levels of reactive oxygen species (ROS), while ROS inhibitor N-acetylcysteine
(NAC) treatment blocked xanthotoxin-induced expression of CncC, MafK, and detoxification genes and
also prevented xanthotoxin-enhanced larval tolerance to λ-cyhalothrin.
The 20-hydroxyecdysone (20E) signaling pathway was effectively activated
by xanthotoxin, while blocking of 20E signaling transduction prevented
xanthotoxin-enhanced larval tolerance to λ-cyhalothrin. Application
of 20E induced the expression of multiple xanthotoxin-induced detoxification
genes and enhanced λ-cyhalothrin tolerance in S. litura. NAC treatment blocked xanthotoxin-induced 20E synthesis, while
the CncC agonist curcumin activated the 20E signaling pathway. These
results indicate that the ROS/CncC pathway controls the induction
of metabolic detoxification upon exposure to xanthotoxin, at least
in part, through its regulation of the 20E signaling pathway.
“…It has been demonstrated that insecticide tolerance in herbivorous insects could arise from utilizing existing detoxification enzymes that evolved to metabolize phytochemicals . The coevolution of herbivorous insects and their host plants has resulted in sophisticated insect detoxification enzyme systems, including cytochrome P450 monooxygenases (P450s), glutathione S -transferases (GSTs), carboxylesterases (CarEs), and uridine diphosphate (UDP)-glycosyltransferases (UGTs). , Up to now, a large number of insect detoxification enzymes that could be induced and metabolize a broad spectrum of phytochemicals, as well as synthetic insecticides, have been identified . For instance, the cotton bollworm, Helicoverpa armigera, maintained on the primary defensive phytochemical gossypol showed elevated tolerance to deltamethrin, and gossypol-induced P450 gene pool contributed to larval tolerance to the pyrethroid insecticide .…”
Tolerance to chemical insecticides can be driven by the necessity of herbivorous insects to defend against host plantproduced phytochemicals. However, how the phytochemicals are sensed and further transduced into a defense response associated with insecticide tolerance is poorly understood. Herein, we show that pre-exposure to flavone, a flavonoid phytochemical, effectively enhanced larval tolerance to multiple synthetic insecticides and elevated detoxification enzyme activities in Spodoptera litura. RNA-Seq analysis revealed that flavone induced a spectrum of genes spanning phase I and II detoxification enzyme families, as well as two transcription factors Cap "n" collar isoform C (CncC) and its partner small muscle aponeurosis fibromatosis (MafK). Knocking down of CncC by RNA interference suppressed flavone-induced detoxification gene expression and rendered the larvae more sensitive to the insecticides. Flavone exposure elicited a reactive oxygen species (ROS) burst, while scavenging of ROS inhibited CncC-mediated detoxification gene expression and suppressed flavone-induced detoxification enzyme activation. Metabolome analysis showed that the ingested flavone was mainly converted into three flavonoid metabolites, and only 3-hydroxyflavone was found to affect the ROS/CncC pathway-mediated metabolic detoxification. These results indicate that the ROS/CncC pathway is an important route driving detoxification gene expression responsible for insecticide tolerance after exposure to the phytochemical flavone.
“…The transcriptomic analysis after larvae were allowed to feed on corn, cotton, and tobacco showed that three expanded P450 gene clusters were significantly induced (Fig. 2 B), suggesting a link between the expansion of P450 gene clusters and increased tolerance to plant toxins [ 13 , 23 ]. Fig.…”
Background
The black cutworm, Agrotis ipsilon, is a serious global underground pest. Its distinct phenotypic traits, especially its polyphagy and ability to migrate long distances, contribute to its widening distribution and increasing difficulty of control. However, knowledge about these traits is still limited.
Results
We generated a high-quality chromosome-level assembly of A. ipsilon using PacBio and Hi-C technology with a contig N50 length of ~ 6.7 Mb. Comparative genomic and transcriptomic analyses showed that detoxification-associated gene families were highly expanded and induced after insects fed on specific host plants. Knockout of genes that encoded two induced ABC transporters using CRISPR/Cas9 significantly reduced larval growth rate, consistent with their contribution to host adaptation. A comparative transcriptomic analysis between tethered-flight moths and migrating moths showed expression changes in the circadian rhythm gene AiCry2 involved in sensing photoperiod variations and may receipt magnetic fields accompanied by MagR and in genes that regulate the juvenile hormone pathway and energy metabolism, all involved in migration processes.
Conclusions
This study provides valuable genomic resources for elucidating the mechanisms involved in moth migration and developing innovative control strategies.
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