Identification of miRNA responsive to early flowering in tree peony (Paeonia ostii) by high-throughput sequencing

MicroRNA (miRNA) belongs to a class of non-coding small RNAs that post-transcriptionally regulate gene expression. In this study, we employed transcriptome, small RNA, and degradome sequencing to systematically investigate the miRNAs in Paeonia ostii. In total, 113 novel miRNA hairpin precursors were predicted, and 123 novel potential miRNAs were identified. Among them, five novel miRNAs and 23 known miRNAs were verified. Expression analyses further reveal that the levels of Pos-miR121, Pos-miR156, and Pos-miR 393 were negatively correlated with the age of Paeonia ostii in leaves, whereas those of Pos-miR159, Pos-miR165, Pos-miR166, Pos-miR172, and Pos-miR319 were gradually increased with age, implying that these miRNAs may play important roles in the acquisition of the floral competence in Paeonia ostii. Taken together, our results provide an important resource for further studies of the molecular basis of floral transition in Paeonia ostii.