The Sex Determination Of The Brown Planthopper,Nilaparvata Lugens

The Brown planthopper(BPH),Nilaparvata lugens,is one of the most destructive pest for rice.At the same time,with the completion of genome and transcription sequencing.BPH has gradually become a model insect for studying gene function of Hemiptera and incompletely metamorphosed insects with its short aeneration,high fertility,simple feeding conditions and effective RNAi interference system.In the evolution of insect species,the mechanism of sex differentiation is an important subject in the basic science of model insects,however,the sex determination mechanism of Hemiptera insect species is still unknown.In this paper,based on the genome and transcriptome data of BPH,the sex determination mechanism of brown planthopper was studied by RNAi interference and other molecular biology techniques.The conclusions are listed as follows:1)Based on the functional and sequences conservation of the doublesex gene in sex determination pathway,we totally found four genes containing the DM domain in the genome and transcriptome of the brown planthopper,named Nldsx and Nldsx-like-1,2,3.And gene Nldsx-like-1 seemed to be more closely related to holometabolous species,Nldsx-like-2 and Nldsx-like-3 were gathered on a branch with mammalian species,and Nldsx appeared farther related to other dsx senes,moreover,only one gene-Nldsx is involved in sex determination.We also found that brown planthopper regulated its gender development through sex-specific expression of male-specific Nldsx-M.2)Gene Transformer-2 is involved in sex determination of Diptera and Hymenoptera,but it does not play a role in the sex determination pathway of Lepidoptera.In this paper,we found that NlTra-2 is involved in the sex determination of brown planthopper.However,unlike Tra-2,which regulates dsx sex-specific alternative splicing in Diptera and Hymenoptera female insects,NlTra-2 inhibits the production of Nldsx-M in female brown planthopper,but has no significant effect on the production of Nldsx-F.3)In this study,we found that there is a cross-talk between sex pathway and wing polyphenism pathway in the brown planthopper.After knocking down the expression level of NITra-2 in the embryonic stage through maternal interference,the female offsprings showed long-winged type,and the male offsprings had not been influenced in the winged form.And,we speculated that there is a female-specific embryonic gene involved in the cross-talk with gene NlTra-2,and gene NIAkt and NIFoxO in the wing pathway may be involved in the cross-talk4)We found a female determine factor-Nlfmd of brown planthopper,and regulated the sex-specific alternative splicing of Nldsx in female brown planthopper,and after maternal RNAi knockdown,the male embryos developed normally and the female embryos died.5)Through the study of this paper,we have drawn a model of BPH sex determination pathway,and we believe that the brown planthopper sex determination pathway is different with the reported insect sex determination pathway.