Abstract: 【Aim】 Ecdysteroid receptor (EcR) was a superfamily nuclear receptor, and it can form a heterodimeric complex EcR/USP with ultraspiracle (USP) protein to adjust the biological activity of 20-hydroxy molting ketone (20E) and regulate the developmental, abnormal and reproductive processes in insect lifecycle. This study aims to clone the full-length cDNA of EcR gene from Ectropis obliqua Prout, and to understand the characteristics of its encoding protein and its expression patterns. 【Methods】 The complete cDNA was cloned from E. obliqua by RT-PCR and RACE technologies. The bioinformatics analysis was carried out by bioinformatics software and editing on online website. The mRNA levels of EcR in different developmental stages and different tissues of the 6th instar larvae were investigated by real-time quantitative PCR (qRT-PCR). 【Results】 The EcR cDNA was cloned successfully from E. obliqua and named Eo-EcR (GenBank accession no. KP869130.1). Its complete length cDNA is 2 268 bp, including a 1 728 bp open reading frame (ORF), which encodes 576 amino acids. Phylogenetic treeanalysis and alignment of amino acid sequences showed that Eo-EcR is highly conserved among insects, especially in Lepidoptera. The results from tertiary structure and function domain prediction indicated that Eo-EcR has three classic structure models and the alpha helix is the dominant structure. It also contains a single functional site with a uni-C₄ type zinc finger structure. qRT-PCR results showed that the expression level of Eo-EcR was higher in the 5th and 6th instar larval stage and adult stage compared to other stages. Tissue expression profiling showed that the expression level of Eo-EcR was the highest in prothoracic gland while lowest in hemolymph. 【Conclusion】 The sequence of nucleotide and characteristics of the encoded amino acid sequence of Eo-EcR were clarified. These results provide a foundation for further researches on the molecular function of Eo-EcR, and bring a new insight for the design of target insecticide to better control E. obliqua.

Key words: Ectropis obliqua, ecdysteroid receptor, clone, bioinformatics, temporal expression, insecticide