Chuvirus-Derived Endogenous Viral Elements Contribute to Nymphal Development Through Modulating the IIS/TOR - 20E...

Area of Science:

• Genomics
• Molecular Biology
• Insect Science

Background:

• Non-retroviral endogenous viral elements (nrEVEs) are integrated viral sequences in host genomes.
• The functions of Chuvirus-derived nrEVEs (ChuEVEs) in insects are largely unknown.
• Rice insect vectors like planthoppers are significant agricultural pests.

Purpose of the Study:

• To investigate the biological roles of ChuEVEs in rice insect vectors.
• To elucidate the molecular mechanisms by which ChuEVEs affect insect development.
• To explore the potential functional domestication of viral elements in insect adaptation.

Main Methods:

• Identification and characterization of ChuEVEs in Sogatella furcifera and Laodelphax striatellus genomes.
• Transcriptional analysis of ChuEVEs across developmental stages and tissues.
• RNA interference (RNAi) mediated knockdown of ChuEVEs and pathway gene silencing.
• Hormonal treatment (20-hydroxyecdysone) to assess pathway rescue.

Main Results:

• Homologous ChuEVEs (SfChuEVE and LsChuEVE) were identified and found to be transcriptionally active, particularly in salivary glands.
• Knockdown of ChuEVEs prolonged nymphal development and altered expression of genes in the 20-hydroxyecdysone (20E) and insulin/insulin-like signalling/target of rapamycin (IIS/TOR) pathways.
• Silencing IIS/TOR components affected 20E pathway genes, but not ChuEVE transcription.
• Exogenous 20E partially rescued 20E pathway gene expression but not IIS/TOR gene expression after ChuEVE knockdown.

Conclusions:

• ChuEVEs play a crucial role in regulating nymphal development in rice planthoppers via an IIS/TOR-20E signaling axis.
• Virus-derived genomic elements can acquire novel developmental functions after endogenization.
• This study expands understanding of endogenous viral element domestication and its contribution to insect adaptation.