Leptosia nina genome

In interactions between plants and herbivorous insects, the insects often evolve key traits that enable them to overcome chemical defenses of their host plants. A prominent example of such adaptive key innovations in herbivorous insects are nitrile-specifier proteins (NSPs) that enabled Pierinae butterflies to colonize Brassicales host plants that employ the glucosinolate-myrosinase defense system. Although the evolutionary aspects of NSP encoding genes have been studied in some Pierinae taxa (especially among Pieris butterflies), the ancestral evolutionary state of NSPs is unclear due to the limited genomic information available for species within Pierinae. Here, we generate a high-quality genome assembly and annotation of Leptosia nina, a member of a small, ancestral tribe, Leptosiaini, within Pierinae. L. nina uses as its main host Capparaceae plants, one of the ancestral hosts within Pierinae. By using ~90 fold coverage of Oxford Nanopore long reads and Illumina short reads for subsequent polishing and error correction, we constructed a final genome assembly that consisted of 286 contigs with a total of 225.8 Mb and an N50 of 10.7 Mb. Genome annotation with transcriptome hints predicted 16,577 genes and covered 98.3% of BUSCO genes. A typical NSP gene is composed of three tandem domains found in Pierinae butterflies; unexpectedly, we identified a new NSP-like gene composed of only two tandem domains. This newly discovered NSP-like gene in L. nina provides important insights into the evolutionary dynamics of domain and gene duplication events relating to host-plant adaptation in Pierinae butterflies.