Reference Transcriptome Data in Silkworm Bombyx mori

SIMPLE SUMMARY: The silkworm Bombyx mori is a lepidopteran model insect with biological and industrial importance. Its high-quality genome sequence has recently become available and the utilization of this information, in combination with extensive transcriptomic analyses, is expected to provide an elaborate gene model. It will also be possible to clarify the gene expression in detail using this approach. In the present study, we established reference transcriptome data for the silkworm and performed a detailed examination of the gene expression in silkworm tissues. The results obtained will contribute to our understanding of silkworm biology and further promote the industrial application of the silkworm and other insects. ABSTRACT: Herein, we performed RNA-seq analysis of ten major tissues/subparts of silkworm larvae. The sequences were mapped onto the reference genome assembly and the reference transcriptome data were successfully constructed. The reference data provided a nearly complete sequence for sericin-1, a major silk gene with a complex structure. We also markedly improved the gene model for other genes. The transcriptomic expression was investigated in each tissue and a number of transcripts were identified that were exclusively expressed in tissues such as the testis. Transcripts strongly expressed in the midgut formed tight genomic clusters, suggesting that they originated from tandem gene duplication. Transcriptional factor genes expressed in specific tissues or the silk gland subparts were also identified. We successfully constructed reference transcriptome data in the silkworm and found that a number of transcripts showed unique expression profiles. These results will facilitate basic studies on the silkworm and accelerate its applications, which will contribute to further advances in lepidopteran and entomological research as well as the practical use of these insects.