Analysis Of Potential Targets For RNAi-based Control—two Female-specific Genes From Nilaparvata Lugens

The brown planthopper (BPH, Nilaparvata lugens) is the primary pests of rice in China and many other Southeast Asian countries. The BPH has a strong reproductive capacity and can rapidly increase its population to damage rice. The females play an important role in population expendings. Therefore, understanding the BPH female genes related to reproductive functions, may provide important theoretical basis for BPH control.In this study, we chose two female-specific genes Nl17034 and N100460 from the Nilaparvata lugens genome and transcriptome. Nl17034 open reading frame (ORF) is 528bp in length, which is potential to encode a predicted 44.21kDa protein containing 175 amino acid residues; N100460 open reading frame (ORF) is 813bp in length, which is potential to encode a predicted 73.03kDa protein containing 270 amino acid residues. The alignment of amino acid sequence showed that Nl17034 is homologous to follicle cell protein 3C (Fcp3C) of Drosophila melanogaster, Blattella germanic, Diploptera punctate and other insects; Nl00460 has no homologous genes with known function. Our results showed that Nl17034 and N100460 are female-specific genes in this species. The expression level of Nl17034 and N100460 gradually increased at the 48th hour after emergence, and peaked at the 60th hour after emergence. qRT-PCR analysis showed that Nl17034 and N100460 are mainly expressed in oocytes. A different localization from the Fcp3C of Drosophila melanogaster which is expressed in follicle cells. Ribonucleic acid interference (RNAi) of Nl17034 and N100460 didn’t lead to death directly, but accelerated the death rate, shorten adult longevity and reduced the expression of NlVg. When Nl17034 was silenced, the oocyte became bleak, short and thick, fat body became loose, and resulted in undeveloped ovaries, the number of eggs was significantly reduced, most of the reproductive ability was lost; When N100460 was silenced, the development of oocyte became slow, the number of eggs and hatching rate were significantly decreased. We hypothesized that the functions of Nl17034 and NL00460 in female BPH are related to the nutrition and development of the oocyte. Nl17034 has the most significant effects on the reproduction of BPH.Our results laid a basis for the further study of Fcp3C and other female-specific genes functions in insect reproduction and RNAi-based control of this rice pest.