关键词: 豌豆蚜, 孤雌生殖, 翅型分化, miRNA, 靶基因, 表达谱

Abstract: 【Aim】 Previous studies revealed that many microRNAs (miRNAs) showed differential expression in the winged and wingless individuals of Sitobion avenae. This study aims to further clarify the exact stage, during which these miRNAs play roles, and to study the functions of miRNAs in the wing dimorphism of the parthenogenetic pea aphid, Acyrthosiphon pisum. 【Methods】 Five miRNAs (Let-7, miR-92a, miR-92b, miR-92a-1-p5 and miR-277) with significantly differential expression levels between winged and wingless individuals of S. avenae and their target genes related to ecdysone, insulin signaling pathway and wing development were selected, and the expression profiles of the miRNAs and their target genes in the 3rd-4th instar nymphs and adults of A. pisum as well as in winged and wingless individuals were detected by qPCR. The above target genes of miRNAs were also verified by dual luciferase activity assay. 【Results】 The expression profiling results indicated that the expression levels of the five miRNAs in adults of A. pisum were higher than those in nymphs, but the expression levels of the predicted target genes in the 4th instar nymphs were higher than those in adults, suggesting that miRNAs might play regulatory roles on their target genes in the adult stage. The expression levels of five miRNAs in winged individuals were higher than those in wingless ones of adults, especially for the miR-277, whose expression level in winged individuals was 7.5 times as high as that in wingless individuals of adults, then followed by Let-7 with threefold expression difference. Moreover, the expression difference of Let-7 between winged and wingless individuals of the 3rd instar nymphs was the most significant, its expression level in the winged individuals being 37.8 times as high as that in wingless ones, then followed by miR-277 with 7.6-fold expression difference. The expression patterns of predicted target genes abrupt and Foxo in the 3rd-4th instar nymphs and winged and wingless individuals of adults of A. pisum were opposite to those of miRNA Let-7 and miR-92b, respectively. Luciferase activity assay results showed that the target gene of Let-7 was abrupt, and the luciferase activity was extremely significantly decreased by 53% compared to the control after co-transfection with the mimics of Let-7. The interaction of other miRNAs with their target genes was not obvious. 【Conclusion】 We first found that the regulation of miRNAs on genes related to wing-morph differentiation of parthenogenetic A. pisum might occur during the adult stage. Let-7 may participate in the wing-morph differentiation of parthenogenetic aphids by regulating abrupt gene. This study lays a foundation for further exploring the mechanism of miRNAs participating in the wing dimorphism of parthenogenetic aphids.

Key words: Acyrthosiphon pisum, parthenogernesis, wing differentiation, miRNA, target gene; expression profile