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

The brown planthopper, <i>Nilaparvata lugens</i>, 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 <i>N. lugens</i> are unclear. In this study, we analyzed the spatiotemporal and temporal expression patterns of five <i>N. lugens</i> proteasome subunits (<i>NlPSMA2</i>, <i>NlPSMB5</i>, <i>NlPSMC4</i>, <i>NlPSMD10</i>, <i>NlPSMD13</i>), and further verified their functions on the transovarial transmission of YLSs, in addition to the reproduction of <i>N. lugens</i>, based on RNA interference (RNAi). The results showed that <i>NlPSMA2</i>, <i>NlPSMB5</i>, <i>NlPSMC4</i>, <i>NlPSMD10</i>, and <i>NlPSMD13</i> were highly expressed in ovarian follicular cells of <i>N. lugens</i> upon sexual maturation. After suppressing the expression of these genes by RNAi, <i>N. lugens</i> 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 <i>N. lugens</i> were significantly increased. These results indicate that the proteasome subunits play crucial roles in the reproduction of <i>N. lugens</i> and the transovarial transmission of its YLSs.