Transcriptome-wide N6-methyladenosine methylome profiling of Bombyx mori reveals a potential mechanism of epigenetic regulation on diapause

Abstract Background Epigenetic regulation may be one of the potential determinants of diapause, which is a strategy for insects to cope with adverse environments and evolution. Epigenetic regulation is multi-dimensional and synergistic, how this combination responds to diapause induced environmental signals and how epigenetic regulation induced by environmental signals precisely regulates insect diapause ware still remain unknown. m6A methylation is one of the most common internal modifications of mRNA, but its regulation on diapause is rarely reported. Results In this study, based on fluorescence immunoassay technology, the m6A abundance of total RNA in the pupal stage of bivoltine silkworm (Bombyx mori) QiuFeng, QFHT (incubated at a normal temperature after HCl acid treatment to produce diapause eggs) and QFLT (incubated at 16.5℃,a low temperature after HCl acid treatment to produce non-diapause eggs) were detected to explore the effects of m6A methylation modification on the diapause traits of the silkworm. The results showed that there were 1563 m6A peaks in QFLT and 659 m6A peaks in QFHT, and together 1,984 m6A peaks. The distribution and enrichment of m6A peak in gene functional elements were significantly different between the two groups. In each signaling pathway of QFLT, the gene transcripts with m6A modification were more diverse, and the methylation level was higher than that of QFHT. The period of epigenetic response to diapause-induced environmental signals was much earlier than the period of diapause phenotype formation, and the epigenetic signals undergo multiple accumulation, transmission and transformation, which may be accompanied by the metamorphosis development and transgenerational regulation of B. mori. Conclusions m6A methylation modification may be one of the molecular markers of diapause regulation or developmental decision, and its specific role in diapause regulation is of great importance for understanding of insect diapause mechanism.