PacBio-based de novo transcriptomics of the coconut rhinoceros beetle Oryctes rhinoceros identifies physiologically important full-length genes and sheds insights into the molecular relationship (chitin synthase) between Scarabaeidae (Coleoptera) and Hymenoptera.

Abstract

The sparser molecular data in non-model insects such as Oryctes rhinoceros prompted us to investigate and identify its physiologically important genes using the novel PacBio Iso-Seq Sequel II platform with single-molecule real-time (SMRT) technology. SMRT library was prepared from various tissues and sequenced. In total, 16,916,297 subreads clustered into 17,547 contigs which collapsed to form 8708 full-length sequences out of which 4352 functionally annotated transcripts were identified. Genes involved in innate immunity, growth and development, hormonal regulation, cellular process, peritrophic membrane, melanogenesis, integument, circulation, cuticle formation, glycan metabolism, etc., were identified. The transcripts' orthologues were identified predominantly in Coleoptera and Hymenoptera in which chitin synthase (CHS), toll, haemocytin, serine protease/limulus clotting factor c, vitellogenin and trehalose transporter exhibited significant molecular relationships between these two insect orders. Chitin synthase 8 (CHS-8) found in ant has been identified for the first time in the order Coleoptera. (O. rhinoceros) at the translational level and projected a potential to explore evolution (horizontal gene transfer) of CHS in insects. The findings will bridge the molecular data between the genome and transcriptome of O. rhinoceros, thus helping develop molecular targets for its control and management.

Supplementary information: The online version contains supplementary material available at 10.1007/s13205-025-04348-9.