A chromosome-level genome assembly of wild silkmoth, Bombyx mandarina.

The wild silk moth, Bombyx mandarina, is the closest relative of the domesticated silk moth, Bombyx mori. National BioResource Project of Japan (NBRP) maintains a B. mandarina strain derived from individuals captured at Sakado (Saitama, Japan) in 1982. Now, NBRP has developed chromosome replacement strains of B. mori. In each strain, one autosome of B. mori was replaced with the corresponding chromosome of B. mandarina. To facilitate the use of chromosome replacement strains and B. mandarina itself, we constructed a chromosome-level genome assembly of B. mandarina. Furthermore, we performed functional annotations of the genome assembly, i.e., transcriptome-based gene prediction, Assay for Transposase-Accessible Chromatin (ATAC)-seq, and PIWI-interacting RNA (piRNA)-targeted small RNA-seq. The assembly harbors 14,859 protein-coding genes and 628 piRNA clusters across three tissues: ovaries, testis, and embryos. ATAC-seq data comprehensively detected open chromosome regions, which will benefit when CRISPR/Cas9-mediated genome editing is conducted.