Tree peony (Paeonia sp.) is a popular traditional ornamental plant in China. Among the nine wild species, Paeonia rockii displays wide-ranging, deep purple variegation at the base of the petals, whereas Paeonia ostii exhibits purely white petals. Overall, the posttranscriptional regulation involved in tree peony flower opening and pigmentation remains unclear. To identify potential microRNAs (miRNAs) involved in flower variegation, six small RNA libraries of P. ostii and P. rockii petals at three different opening stages were constructed and sequenced. Using Illumina-based sequencing, 22 conserved miRNAs and 27 novel miRNAs were identified in P. rockii and P. ostii petals. Seventeen miRNAs were differentially expressed during flower development, and several putative target genes of these miRNAs belonged to transcription factor families, such as Myb domain (MYB), and basic helix-loop-helix (bHLH) transcription factors. Furthermore, an integrative analysis of the expression profiles of miRNAs and their corresponding target genes revealed that variegation formation might be regulated by miR159c, miR168, miR396a, and novel_miR_05, which target the MYB transcription factors, chalcone synthase (CHS), and ABC transporter. Our preliminary study is the first report of miRNAs involved in Paeonia flower pigmentation. It provides insight regarding the molecular mechanisms underlying the regulation of flower pigmentation in tree peony.
This work was supported by the Natural Science Foundation of China (31800599), Natural Science Foundation of Shannxi Province, China (2017JQ3024), General Financial Grant from the China Postdoctoral Science Foundation (2017M623267), the Special Fund for Scientific Research in the Public Welfare (201404701), the Scientific Startup Foundation for Doctors of Northwest A&F University (Z109021611), and Fundamental Research Funds for the Central Universities (Z109021606).
Qianqian Shi and Xiaoxiao Zhang performed the experiments and data analysis and wrote the manuscript. Xiang Li performed some experiments. Xiaoning Luo, Jianrang Luo, and Lixia He helped prepare the plant material. Yanlong Zhang and Long Li designed this research study. All of the authors read and approved the final manuscript.
These authors contributed equally to this work and should be considered co-first authors.
Corresponding authors. Email: email@example.com or firstname.lastname@example.org.
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