miR-PC-3p-241582_34 Contributes to the Infection of <i>Athetis lepigone</i> by Regulating the Expression of <i>HSWP4</i> in <i>Nosema bombycis</i>

<i>Athetis lepigone</i> is a recurring pest in the maize seedling stage under the wheat-maize no-tillage direct seeding system in China's summer maize region. Our previous research identified a highly pathogenic <i>Nosema bombycis</i> to <i>A. lepigone</i>, which spore wall protein plays an important role in the infection process. However, the regulatory mechanism of this spore wall protein is still unclear. In this study, we explored the regulatory mechanism of miRNAs on spore wall proteins. Transcriptome sequencing results showed that expression of the spore wall protein, <i>HSWP4</i>, significantly increased in the germination group compared to dormancy group. Silencing of <i>HSWP4</i> reduced the number of microsporidian spores breaking through the midgut wall cells of <i>A. lepigone</i>. Association analysis of small RNA and mRNA revealed that the targeting site of miR-PC-3p-241582_34 on <i>HSWP4</i> was located in the CDS region, and miR-PC-3p-241582_34 had a significant negative regulatory relationship with <i>HSWP4</i>. The dual luciferase reporter assay demonstrated that miR-PC-3p-241582_34 significantly affected the luciferase activity of the <i>HSWP4</i>-3'UTR expression vector (<i>P</i> < 0.05). Delivery of miRNA mimics decreased the expression of <i>HSWP4</i> and inhibited the behavior of microsporidian spores breaking through the midgut wall of <i>A. lepigone</i>. On the other hand, delivery of inhibitors produced opposite results, indicating that the miR-<i>HSWP4</i> pathway plays an important role in microsporidian infection of <i>A. lepigone</i>. This study provides a new theoretical basis for understanding the pathogenic mechanism and gene regulation of microsporidia, as well as for the green control of <i>A. lepigone</i>.