Functional characterization of the cis-regulatory region for the vitellogenin gene in Plutella xylostella

The vitellogenin gene promoter (VgP) is an essential cis-regulatory element that plays a significant role in transcription of the vitellogenin (Vg) gene, leading to the production of yolk protein in insects, including lepidopterans. However, the function of VgP is still not clear in Plutella xylostella. Here, we cloned a 5.1 kb DNA fragment of the cis-regulatory region adjacent to the 5 ' end of the Vg gene of P. xylostella (PxVg). We identified two promoter sites in that 5 ' upstream sequence of PxVg and performed in vitro analysis of two promoter sequences (PxVgP1, 4.9 kb, and PxVgP2, 2.9 kb) in the embryonic cell line of P. xylostella. PxVgP2 exhibited higher enhanced green fluorescent protein (EGFP) expression, so PxVgP2 was used for in vivo analysis. Strong EGFP fluorescence was observed in adult females and the fat body of females, with low expression in embryos. Our results suggest that PxVgP is an important stage-, tissue- and sex-specific endogenous cis-regulatory element in P. xylostella.