Abstract: 【Aim】To explore the role of 3-hydroxy-3-methylglutaryl coenzyme A reductase gene (HMGR), a key gene of juvenile hormone (JH) biosynthesis, in the reproduction of the white-backed planthopper, Sogatella furcifera.【Methods】Based on the published genome and transcriptome data of S. furcifera, the full-length cDNA sequence of SfHMGR was obtained by RT-PCR. The expression profiles of SfHMGR in different developmental stages (1st-5th instar nymph and female adult) and different tissues (head, gut, fat body, ovaries and integument) of female adults of S. furcifera were detected by RT-qPCR. After targeted silencing of SfHMGR by RNAi technology, the ovarian development of female adults was observed, the number of eggs laid by per female adult of S. furcifera was counted, and the transcription levels of downstream genes of JH biosynthesis (SfJHAMT and SfFAMeT), JH signal transduction related genes (SfMet and SfKr-h1), and the key genes of ovarian development (SfVg and SfVgR) were determined by RT-qPCR. 【Results】The full-length cDNA sequence of SfHMGR (GenBank accession number: MW883397) of S. furcifera was cloned, with an open reading frame of 2 724 bp in length, encoding 907 amino acids. The predicted molecular weight of the protein is 98.96 kD, and the theoretical isoelectric point is 6.15. Sequence analysis showed that SfHMGR contains typical HMG-CoA reductase conserved domain, three HMG-CoA binding sites at the C-terminus and seven transmembrane domains at the N-terminus. Phylogenetic analysis showed that SfHMGR has the closest genetic relationship with HMGR of Laodelphax striatellus and Nilaparvata lugens, showing 92.40% and 89.25% amino acid sequence identities with them, respectively. The developmental expression profiles showed that SfHMGR was highly expressed in the middle of various developmental stages and newly emerged female adults. The tissue expression profiles showed that SfHMGR was expressed in various tissues of female adults, and had the highest transcription level in gut. After the inhibition of SfHMGR expression by microinjection of dsRNA, the number of eggs laid by per female and ovarian development of female adults, and the transcription levels of SfJHAMT, SfFAMeT, SfKr-h1, SfVg and SfVgR were significantly inhibited. 【Conclusion】SfHMGR regulates the transcription level of SfVg by affecting the JH biosynthesis process and JH signal transduction, and then affects the ovarian development and the fecundity of female adults of S. furcifera.

Key words: Sogatella furcifera, 3-hydroxy-3-methylglutaryl coenzyme A reductase, juvenile hormone, reproduction, ovarian development