De Novo Long-Read Genome Assembly and Annotation of the Luna Moth (Actias luna) Fully Resolves Repeat-Rich Silk Genes

Abstract

We present the first long-read de-novo ­assembly and annotation of the luna moth (Actias luna) and provide the full characterization of heavy chain fibroin (h-fibroin)­­, a long and highly repetitive gene (>20 Kbp) essential in silk fiber production. There are more than 160,000 described species of moths and butterflies (Lepidoptera), but only within the last five years have we begun to recover high-quality annotated whole genomes across the order which capture h-fibroin. Using PacBio HiFi reads, we produce the first high-quality long-read reference genome for this species. The assembled genome has a length of 532 Mbp, a contig N50 of 16.8 Mbp, an L50 of 14 contigs, and 99.4% completeness (BUSCO). Our annotation using Bombyx mori protein and A.luna RNAseq evidence captured a total of 20,866 genes at 98.9% completeness with 10,267 functionally annotated proteins and a full-length h-fibroin annotation of 2,679 amino acid residues.