Abstract: 【Aim】To identify microRNAs (miRNAs) in the small brown planthopper, Laodelphax striatellus infected with Wolbachia, a symbiotic bacterium that regulates host fecundity.【Methods】Small RNA sequencing technique was used to identify miRNAs in the ovaries of the 3-day-old female adults of L. striatellus infected and uninfected with Wolbachia, so as to screen the differentially expressed miRNAs, which were subsequently aligned to the L. striatellus genome to ascertain the small RNAs matched to the reference sequence. miRanda and RNAhybrid were used to predict the target genes of differentially expressed miRNAs. The expression levels of these differentially expressed miRNAs and their target genes in the ovaries of female adults of L. striatellus infected and uninfected with Wolbachia were detected using qRT-PCR. 【Results】 Seven differentially expressed miRNAs (novel_47, novel_48, novel_60, novel_76, novel_88, novel_160 and novel_184) were identified in the ovaries of female adults of L. striatellus infected and uninfected with Wolbachia. The expression level of novel_47 in the ovaries of female adults of L. striatellus uninfected with Wolbachia was significantly higher than that in the ovaries of female adults of L. striatellus infected with Wolbachia. Conversely, the expression level of novel_184 in the ovaries of female adults of L. striatellus infected with Wolbachia was significantly higher than that in the ovaries of female adults of L. striatellus uninfected with Wolbachia. The remaining miRNAs (novel_48, novel_60, novel_76, novel_88 and novel_160) showed extremely significantly higher expression levels in the ovaries of female adults of L. striatellus infected with Wolbachia than in the ovaries of female adults of L. striatellus uninfected with Wolbachia. The expression level of LsJHE (a target gene of novel_47) in the ovaries of female adults of L. striatellus infected with Wolbachia was significantly higher than that in the ovaries of female adults of L. striatellus uninfected with Wolbachia. The target genes of novel_48, novel_160 and novel_184 (LsMFS, LsCarE25 and LsTreT, respectively) in the ovaries of female adults of L. striatellus uninfected with Wolbachia exhibited significantly elevated expression levels as compared to those in the ovaries of female adults of L. striatellus infected with Wolbachia. The target genes of novel_60, novel_76 and novel_88 (LsCYP315A1, LsPOD and LsJHAMT, respectively) in the ovaries of female adults of L. striatellus uninfected with Wolbachia demonstrated extremely significantly elevated expression levels as compared to those in the ovaries of female adults of L. striatellus infected with Wolbachia. 【Conclusion】This study successfully identified seven differentially expressed miRNAs and their potential target genes in the ovaries of female adults of L. striatellus infected and uninfected with Wolbachia. These findings provide valuable candidate genes for exploring the regulatory mechanisms of miRNAs in Wolbachia-mediated fecundity enhancement in L. striatellus females. Furthermore, the results also provide potential molecular targets for the applications of these miRNAs and Wolbachia in developing novel control strategies against L. striatellus.

Key words: Laodelphax striatellus, Wolbachia, microRNA, target gene, reproduction, small RNA sequencing