Objective Vitellogenin (Vg) and its receptor (VgR) play key roles in insect reproduction by mediating nutrient transport during oocyte vitellogenesis.This study aimed to clone Vg and VgR from the Thalassodes immissaria, a notorious defoliator in lichee, and analyzed their bioinformatics characteristics and expression patterns across developmental stages to infer their roles in reproductive regulation.

Method Using transcriptome data of T.immissaria, the full-length cDNA sequences of TiVg and TiVgR were cloned via PCR.Bioinformatics tools, such as ORF Finder, SignalP 5.0, ProtParam, SMART, TMHMM 2.0, and MEGA v5.05, were used for sequence analysis.Expression profiles of TiVg and TiVgR across different developmental stages and different tissues were quantified using transcriptomic TPM values and qRT-PCR.

Result The open reading frames (ORFs) of TiVg and TiVgR span 5 343 and 5 250 bp respectively, encoding polypeptides of 1 780 and 1 749 amino acids, with predicted molecular weights of 202.403 and 196.248 kDa.Both TiVg and TiVgR are water-soluble, exhibiting hydropathicity index of-0.681 and-0.329, respectively.The N-termini of TiVg and TiVgR contain signal peptide regions composed of 16 and 14 amino acid residues, respectively.The phylogenetic analysis suggested that TiVg clusters within the Operophtera brumata ObVg clade, while TiVgR aligns closely with Helicoverpa armigera HaVgR orthologs.The expression pattern results with TPM value showed that TiVg expression initiated at the pupal stage and peaked in adult females, whereas TiVgR exhibited maximal expression in adult females with minimal levels detected in eggs.Tissue expression pattern suggested that TiVg was highly expressed in fat body of adult females and TiVgR was highly expressed in ovary of adult females, respectively.

Conclusion The study successfully cloned Vg and VgR from T.immissaria.The conserved motifs and the expression patterns in both developmental stage and tissues suggest their potential roles in reproductive regulation.These findings provide a foundation for understanding reproductive mechanisms in T.immissaria.