Submission Type
Oral Presentation
Abstract
Various Coleoptera (beetles) and Lepidoptera (moths) insects are known to produce highly active antifreeze peptides (AFPs), an adaptive trait that enabled them to avoid freezing and survive severe winters. These include the grain pest Tenebrio molitor (yellow mealworm), pine-boring Rhagium beetles, the fire-colored Dendroides beetles, a stag beetle, and the Choristoneura spruce budworms (moths). Insect AFPs are small peptides of ~8 to 15 kDa, consisting of several tandem 13-amino acid repeats of similar sequences, each ending with a conserved tripeptide Thr-Cys/aa-Thr motif, found to be important for ice binding. Except for the eastern spruce budworm, the evolutionary origin/s and process/es of these novel AFPs are currently unknown. We conducted comparative genomic analyses of three select beetle species - T. molitor and its congener T. obscurus (Tenebrionidae), and the distant D. canadensis (Pyrochroidae) to test the hypothesis that similar AFPs in divergent insects evolved convergently. We sequenced the three species by PacBio HiFi long-read sequencing and assembled the genomes to high contiguity. We annotated the AFP gene family and characterized the AFP genomic locus and neighboring regions in each species. The AFP family of T. molitor and T. obscurus contains 43 and 53 AFP copies, respectively, spanning ~1Mbp and mapping to a single orthologous genomic region. In contrast, D. canadensis AFP family (21 copies) is dispersed in six large contigs. Broader scale synteny analyses show the genomic neighborhood of the AFP loci of the two Tenebrio is distinct from those of the six AFP loci of D. canadensis. The disparate genomic organization and the lack of shared microsynteny of the AFP loci between the Tenebrio species and D. canadensis are inconsistent with a common origin of the AFP gene, but strongly support convergent evolution of very similar antifreeze protein sequences in these two distant insect lineages.
Included in
Convergent evolution of antifreeze proteins in two insect families supported by whole genome and gene family loci analyses
Various Coleoptera (beetles) and Lepidoptera (moths) insects are known to produce highly active antifreeze peptides (AFPs), an adaptive trait that enabled them to avoid freezing and survive severe winters. These include the grain pest Tenebrio molitor (yellow mealworm), pine-boring Rhagium beetles, the fire-colored Dendroides beetles, a stag beetle, and the Choristoneura spruce budworms (moths). Insect AFPs are small peptides of ~8 to 15 kDa, consisting of several tandem 13-amino acid repeats of similar sequences, each ending with a conserved tripeptide Thr-Cys/aa-Thr motif, found to be important for ice binding. Except for the eastern spruce budworm, the evolutionary origin/s and process/es of these novel AFPs are currently unknown. We conducted comparative genomic analyses of three select beetle species - T. molitor and its congener T. obscurus (Tenebrionidae), and the distant D. canadensis (Pyrochroidae) to test the hypothesis that similar AFPs in divergent insects evolved convergently. We sequenced the three species by PacBio HiFi long-read sequencing and assembled the genomes to high contiguity. We annotated the AFP gene family and characterized the AFP genomic locus and neighboring regions in each species. The AFP family of T. molitor and T. obscurus contains 43 and 53 AFP copies, respectively, spanning ~1Mbp and mapping to a single orthologous genomic region. In contrast, D. canadensis AFP family (21 copies) is dispersed in six large contigs. Broader scale synteny analyses show the genomic neighborhood of the AFP loci of the two Tenebrio is distinct from those of the six AFP loci of D. canadensis. The disparate genomic organization and the lack of shared microsynteny of the AFP loci between the Tenebrio species and D. canadensis are inconsistent with a common origin of the AFP gene, but strongly support convergent evolution of very similar antifreeze protein sequences in these two distant insect lineages.
Comments
Pomona Carrington-Hoekstra, University of Illinois at Urbana-Champaign
C-H. Christina Cheng, University of Illinois at Urbana-Champaign