sRNA Sequencing of Dahlia Bicolor Petals Revealed the Post-Transcriptional Regulation of Anthocyanin Biosynthetic Pathway

Garden dahlias (Dahlia pinnata) are popular for their rich flower color variations that have produced many typical bicolor cultivars. Previous studies on the anthocyanin biosynthetic pathway (ABP) observed that the miR156-SPL9 module contributes to the formation of white tips on dahlia petals by repressing the MYB-bHLH-WDR complex. In this study, we further detected the potential post-transcriptional regulation involved in the bicolor petal formation by the small RNA sequencing of red bases and white tips. Compared with red bases, 89 differentially expressed miRNAs and 6349 target genes were identified. And 78 up-regulated miRNAs with their 249 down-regulated target genes were involved in the formation process of white petal tips. The target genes of differentially expressed miRNAs significantly enriched in the ABPs and miRNAs of six conserved families (MIR 156, 164, 167, 169, 482 and 6114) targeted to four transcription factor families (ARF, HD-ZIP, SBP and NAC) were involved in the post-transcriptional gene silencing (PTGS) of the ABP. Transcription sequencing and quantitative reverse transcription PCR analysis demonstrated that the MIR167-ARF8 module and the MIR6114-ANL2 module were the candidate regulators of the inactive ABP in the white tips by depressing the transcription of multiple structure genes. The findings gave new insights into the post-transcriptional regulation of the ABP and would be valuable for further studies of the PTGS mechanisms of bicolor petal formation.