m 6 A-dependent mevalonate kinase in juvenile hormone synthesis pathway regulates the diapause process of bivoltine silkworm ( Bombyx mori )

Background Research has shown that epigenetic modification are involved the regulation of diapause in bivoltine silkworms ( Bombyx mori ), but it remains unclear how epigenetic modification in response to environmental signals precisely to regulate the diapause processing of bivoltine B. mori . Methods and results In this study, the diapause terminated eggs of bivoltine B. mori , Qiufeng (QF) were divided into two groups: a QFHT group incubated at 25 °C with a natural day/night cycle to produce diapause eggs, and a QFLT group incubated at 16.5 °C in darkness to produce non-diapause eggs. On the 3rd day of the pupal stage, the total RNAs of the eggs were extracted and their N6-adenosine methylation (m 6 A) abundances were analyzed to explore the effects of m 6 A methylation on diapause in the silkworm. The results showed that 1984 m 6 A peaks are shared, 1563 in QFLT and 659 in QFHT. The m 6 A methylation level of the QFLT group was higher than that of the QFHT one in various signaling pathways. The m 6 A methylation rate of mevalonate kinase ( MK ) in the insect hormone synthesis pathway was significantly different between the two groups. The knockdown of MK by RNA interference in the pupae of QFLT resulted in females laying diapause eggs rather than non-diapause eggs after mating. Conclusions m 6 A methylation involves in the diapause regulation of bivoltine B. mori by changing the expression levels of MK . This result provides a clearer image of the environmental signals on the regulation of diapause in bivoltine silkworms.