The Annotation of De Novo Genome Assembly of the Silkworm, Bombyx mori Linn., Strain Nang Tui as Thai reference genome

Thailand is one of the most famous silk production regions, where silkworms (Bombyx mori Linn.) have been reared for sericulture for a long time. Thai silk holds the cultural importance. Several strains of silkworm have been bred and preserved by the Queen Sirikit Department of Sericulture, national administration responsible for maintaining silkworm strains in Thailand. Their efforts aim to improve the silkworm strains with desired traits and breed these traits into future generations. Therefore, the production of genetic database of silkworm reference genome, including genome annotation is crucial. This study aimed to present and annotate the polyvoltine silkworm reference genome through de novo genome sequencing of strain Nang Tui which exhibits high silk productivity and tolerance to high temperature. The estimated size of draft de novo genome assembly of strain Nang Tui was 701,413,529 bp containing 21,421 contigs. The completeness of genome assembly of Nang Tui was validated using BUSCO analysis, which revealed 90.10% single-copy BUSCOs. For gene prediction, this genome assembly harbors 337 protein-coding genes and 65 transposable elements, as predicted using the B. mori gene annotation from NCBI. Moreover, 4 rRNA and 18 tRNA-related genes were identified. The most enriched gene ontology (GO) term was plasma membrane (GO:0005886). The signaling pathway had the highest number of gene enrichments based on KEGG pathway analysis. The mononucleotide repeats were the most abundant type, with the A/T motif being the most frequent in this assembly. Moreover, genes encoding fibroin and sericin which are the main components of silk were identified. Furthermore, genes encoding serine protease inhibitors which are reported to have antimicrobial activity, were also found. Accordingly, the draft de novo genome assembly of strain Nang Tui demonstrated the high completeness and comprehensive annotation, which could serve as the novel polyvoltine silkworm reference genome and make it a valuable resource for studying the genetic diversity of various silkworm species and strains in Thailand. Furthermore, it could accelerate the understanding of molecular mechanisms for superior silk production in the future.