Wolbachia-induced cytoplasmic incompatibility triggers intergenerational dysregulation of the small RNA regulatory network in offspring

The intracellular symbiont <i>Wolbachia</i>, which is widespread among insects, may induce cytoplasmic incompatibility (CI) between hosts with different infection statuses. Increasing evidence indicates that symbiotic bacteria can influence host reproduction, metabolism, and other biological processes by modulating non-coding small RNAs. However, it is still unclear how <i>Wolbachia</i>-induced CI affects the offspring reproduction. In this study, using <i>Drosophila melanogaster</i> as a model system, small RNA and transcriptome sequencing were conducted on the reproductive systems of the offspring resulting from crosses between <i>Wolbachia</i>-infected males and uninfected females. By comparing F1 males and females to their respective paternal or maternal lines, we identified distinct intergenerational discrepancies. The male offspring of the CI cross showed a significant upregulation of immune-related genes and a notable downregulation of reproductive-related genes. Moreover, the microRNA regulatory network in the testes of the offspring was significantly disrupted, with the target genes directly involved in embryonic development, energy metabolism, immune regulation, and reproductive behavior. Additionally, increased transposable element (TE) expression and piRNA dysregulation were observed in the testes of male offspring. Overall, this study offered new insights into the intergenerational regulatory effects of <i>Wolbachia</i>-induced CI and its potential mechanisms.