Exploring miRNA-target modules in Paeonia lactiflora stamen petalization through integrated miRNAome, transcriptome, and degradome analysis

Variation in floral organ number in plants is triggered by extremely complex transcriptional and posttranscriptional regulatory processes. MicroRNAs (miRNAs) play a pivotal role in the post-transcriptional regulation of floral organs. Paeonia lactiflora Pall., originating from China, is a precious herbaceous plant with ornamental, medicinal, and oil properties. Building on previous transcriptional studies, this work examined posttranscriptional regulation of peony stamen petalization using critical-stage flower buds. Using high-throughput small RNA sequencing, a miRNA expression profile was constructed. This was used to identify 10 known, 334 conserved, and 255 novel miRNAs, 155, 151, and 44 of which were differentially expressed at three developmental stages (stamen primordium, stamen primordium partly petaloid, and stamen primordium completely petaloid). Degradome analysis identified 55 miRNAs and 127 potential target genes. A miRNA-target network suggested that miR172- PlRAP2 , miR160- PlARF , miR396- PlGRF , miR319- PlTCP4 , and miR384\394- PlFBOX modules are key regulators of peony stamen petalization. The regulation of miR319 and PlTCP4 during peony flower development was validated through transient expression in tobacco. This study provides insight into miRNA-mediated regulation of petalized stamen formation in herbaceous peony and refines the posttranscriptional network at critical stages of this process.