Proteasome Subunits Regulate Reproduction in Nilaparvata lugens and the Transovarial Transmission of Its Yeast-like Symbionts.

The brown planthopper, Nilaparvata lugens, a major rice pest, harbors yeast-like symbionts (YLSs) that form mutualistic relationships with the host, significantly influencing its development and reproduction. As proteasome subunits play major roles in the assembly and functional maintenance of the proteasome, but their regulation on the YLSs in N. lugens are unclear. In this study, we analyzed the spatiotemporal and temporal expression patterns of five N. lugens proteasome subunits (NlPSMA2, NlPSMB5, NlPSMC4, NlPSMD10, NlPSMD13), and further verified their functions on the transovarial transmission of YLSs, in addition to the reproduction of N. lugens, based on RNA interference (RNAi). The results showed that NlPSMA2, NlPSMB5, NlPSMC4, NlPSMD10, and NlPSMD13 were highly expressed in ovarian follicular cells of N. lugens upon sexual maturation. After suppressing the expression of these genes by RNAi, N. lugens exhibited a shortened lifespan, abnormal pear-shaped follicles, and impaired oviposition capacity, but the number of YLSs in the whole body and the oocyte of N. lugens were significantly increased. These results indicate that the proteasome subunits play crucial roles in the reproduction of N. lugens and the transovarial transmission of its YLSs.