AUTHOR=Zhang Jing , Zhang Zhenyu , Zhang Rui , Zhang Wenfei , Li Haozhe , Li Tianran , Zhang Hongyu , Zheng Weiwei 

TITLE=Identification of COP9 Signalosome Subunit Genes in Bactrocera dorsalis and Functional Analysis of csn3 in Female Fecundity

JOURNAL=Frontiers in Physiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2019.00162

DOI=10.3389/fphys.2019.00162

ISSN=1664-042X

ABSTRACT=<p>The COP9 signalosome (CSN) is an evolutionarily conserved multi-subunit complex that plays crucial roles in regulating various biological processes in plants, mammals, and the model insect <italic>Drosophila</italic>. However, it is poorly studied in non-model insects, whereas its role in fecundity remains unclear. In this study, all nine CSN subunits were identified and characterized in <italic>Bactrocera dorsali</italic>s, a major invasive agricultural tephritid pest. Each subunit gene, except for <italic>csn9x1</italic>, encoded a protein containing a PCI/PINT or MPN domain. Phylogenetic analysis revealed that all CSN subunits were individually clustered into a specific branch with their counterparts from other species. All CSN subunit genes were expressed in all detected developmental stages and tissues. Most subunits, except for <italic>csn8</italic> and <italic>csn9x1</italic>, showed the highest expression level in the eggs. Notably, <italic>csn</italic>3 and <italic>csn</italic>5 were significantly enriched in mature female adults. Further analysis of <italic>csn3</italic> revealed that it was enriched in the ovary and that its ovarian expression level gradually increased with the reproductive development process. RNAi-based knockdown of <italic>csn3</italic> in female adults significantly reduced the number of laid eggs. The expression level of <italic>EcRB1</italic> and <italic>USP</italic>, which encode the heterodimer receptors of 20E, and vitellogenin transcripts (<italic>Vg1</italic> and <italic>Vg2</italic>) was suppressed in the fat body of female adults injected with <italic>csn3</italic>dsRNA. Decreased level of Vg1 protein was confirmed by means of Western blots. These data indicate that <italic>csn3</italic> is involved in female reproduction by regulating 20E signaling and Vg synthesis. Overall, our study may facilitate the development of new strategies for controlling <italic>B. dorsali</italic>s since it provides insights into the evolution and expression patterns of all CSN subunit genes as well as the critical roles of <italic>csn3</italic> in female fecundity.</p>