Transcription factor E93 regulates vitellogenesis via the vitelline membrane protein 26Ab gene in Chilo Suppressalis

Ecdysone-induced protein 93 F (E93, also known as Eip93F) plays a crucial role in the reproductive process of numerous insects. This study aims to delineate the function of E93 in Chilo suppressalis and elucidated the regulatory mechanism by which E93 influences the reproduction of C. suppressalis

The results of the bioinformatics analysis indicate that C. suppressalis E93 shows the highest homology with E93 from Bombyx mori. We used qPCR to evaluate the expression profile of CsE93 from different developmental stages and tissues, revealed that CsE93 had the highest expression levels in the head, which peaked during the prepupal stage. Silencing CsE93 resulted in a significant reduction in yolk deposition and abnormal ovarian development. Moreover, the transcriptional levels of vitellogenin (Vg) and E74A, which are related to vitellogenesis and the 20E pathway, were significantly down-regulated in dsE93-treated female pupae. In addition, we identified Vitelline membrane protein 26Ab (VMP26Ab), a downstream gene associated with the integrity of the inner eggshell. The knockdown of VMP26Ab resulted in a significant reduction in the number of eggs and abnormal ovarian development, similar to RNAi E93. Finally, we identified an active promoter fragment (containing GAGA-containing motif) of CsVMP26Ab and demonstrated that CsE93 can bind to it.

Our results indicate that CsE93 plays an important role in C. suppressalis reproduction. CsE93 modulates the CsVMP26Ab expression by acting on its promoter involve in the reproduction of C. suppressalis finally.