Knockdown of the chromatin remodeling ATPase gene Brahma impairs the reproductive potential of the brown planthopper, Nilaparvata lugens

The brown planthopper (BPH), Nilaparvata lugens (Stål), is one of the most destructive pests in rice-growing regions of Asia. Extensive studies have suggested that SWI/SNF chromatin remodeling ATPase Brahma (BRM) plays multiple roles in the insect model Drosophila. Yet much less is known about the physiological properties for NlBRM. In the present study, the cloned full-length cDNA of NlBRM was 5637 bp and contained an ORF of 5292 bp encoding a 194.53 kD protein. The spatiotemporal dynamics of NlBRM was investigated by qPCR, which showed that it was abundantly expressed in the egg and ovary. Then significant downregulation of NlBRM by dsRNA injection had a relatively greater impact on female survival than male. Moreover, the number of oviposition marks of the NlBRM-RNAi females were declined by 61.11% - 73.33% compared with the controls during the subsequent 5 days after dsRNA injection. Meanwhile, the number of newly hatched BPH nymphs also decreased correspondingly by 93.56% - 100%. Phenotypic analysis revealed that none of normally banana-shaped eggs were discernable in the ovaries of NlBRM-deficient females, where mRNA expression of N. lugens vitellogenin gene was also reduced. Our results demonstrated that NlBRM played a crucial role in ovarian development and fecundity of BPH, likely by regulating the vitellogenin gene in vivo, which could be as a promising target for parental RNAi-based control of this serious rice pest.