DGAT1-mediated lipid metabolism is essential for female reproduction in the silkworm, Bombyx mori.

Lipid metabolism plays a critical role in maintaining energy homeostasis during various physiological processes in insects. Diacylglycerol O-acyltransferase-1 (DGAT1) is associated with the synthesis of triacylglycerol (TAG), a process that is necessary for the absorption of dietary fats and the storage of fat in mammals. However, the biological roles of DGAT1 in insects remain largely unknown. In this study, we identified and characterized the DGAT1 gene in Bombyx mori. Temporal and spatial expression profiles showed that BmDGAT1 was broadly expressed in all examined tissues and had higher expression in the midgut and gonads. BmDGAT1 mutants were obtained by a binary transgenic CRISPR/Cas9. Disruption of BmDGAT1 resulted in a significant decrease in the body weight of larvae and pupae, and reduced the content of TAG. In addition, deletion of BmDGAT1 hindered ovarian development and completely inhibited the formation of mature eggs in female adults. Meanwhile, a dramatic reduction in the TAG content was observed in the ovaries of BmDGAT1 mutants. Furthermore, the RNA-sequencing and quantitative real-time polymerase chain reaction (qRT-PCR) analyses revealed that knockout of BmDGAT1 affected the expression of genes associated with female reproduction in the mutants. Altogether, DGAT1-mediated lipid metabolism plays a key role in regulating silkworm female reproduction, which is a potential target for controlling lepidopteran pests.