Abstract: 【Aim】 This study aims to identify microRNA (miRNA) and possible target genes involved in the gonadal development of Bombyx mori through miRNA microarray and transcriptome analyses of the testis and ovary of the 5th instar larvae of B. mori. 【Methods】 A new generation of highthroughput sequencing platform was used to perform miRNA microarray analysis and transcriptome sequencing of the testis and ovary (defined as test and control, respectively) of the 5th instar larvae of B. mori. According to the criteria of P<0.05 and log₂(fold change, FC)≥2, the differentially expressed miRNAs of test vs control were screened. According to the criteria of q≤0.05 and ［log₂ (fold change)］≥1, the differentially expressed genes (DEGs) of test vs control were screened by comparative analysis. Eight up-regulated and 12 down-regulated differentially expressed miRNAs were randomly selected,and their expression and their predicted five target genes were verified by qRT-PCR. The DEGs and target genes of the differentially expressed miRNAs were enriched by KEGG pathway analysis. 【Results】 Sixty-eight differentially expressed miRNAs and 3 991 DEGs were identified from the testis and ovary (test vs control). Among them, 36 and 32 miRNAs were up-regulated and down-regulated, respectively, and 2 033 and 1 958 DEGs were up-regulated and down-regulated, respectively. qRT-PCR verification results of differentially expressed miRNAs were consistent with the microarray data. KEGG pathway enrichment analysis showed that the DEGs were significantly enriched in the signal pathways involved in metabolism and ribosome. The possible target genes of differentially expressed miRNAs in the DEGs were predicted. Four groups of miRNAs and their target genes showing the opposite expression trend were found, including bmo-miR-2774a and LOC101745556, bmo-miR-92b and LOC101735954, bmo-miR-3266 and LOC733130 and LOC778467, respectively. One group of miRNA and its target gene showing the consistent expression trend was bmo-miR-3321 and LOC101744895. The results of qRT-PCR of five target genes were consistent with the results of transcriptome sequencing. 【Conclusion】 In this study, the transcriptome and miRNA microarray data of the testis and ovary of the 5th instar larvae of B. mori have been obtained, and four groups of miRNAs and their target genes showing the opposite expression trend and one group of miRNA and its target gene showing the consistent expression trend screened and verified, laying a foundation for exploring the development differences between the testis and ovary of B. mori.

Key words: Bombyx mori, testis, ovary, miRNA, miRNA microarray, transcriptome