Dual functions of PsmiR172b-PsTOE3 module in dormancy release and flowering in tree peony (Paeonia suffruticosa)

Abstract

MicroRNAs (miRNAs) are non-coding RNAs that interact with target genes and are involved in many physiological processes in plants. miR172-AP2 mainly plays a role in the regulation of flowering time and floral organ differentiation. Bud dormancy release is necessary for forcing culture of tree peony in winter, but the mechanism of dormancy regulation is unclear. In this study, we found that a miR172 family member, PsmiR172b, was downregulated during chilling-induced bud dormancy release in tree peony, exhibiting a trend opposite to that of PsTOE3. RNA ligase-mediated (RLM) 5'-RACE (rapid amplification of cDNA ends) confirmed that miR172b targeted PsTOE3, and the cleavage site was between bases 12 (T) and 13 (C) within the complementary site to miR172b. The functions of miR172b and PsTOE3 were detected by virus-induced gene silencing (VIGS) and their overexpression in tree peony buds. PsmiR172b negatively regulated bud dormancy release, but PsTOE3 promoted bud dormancy release, and the genes associated with bud dormancy release, including PsEBB1, PsEBB3, PsCYCD, and PsBG6, were upregulated. Further analysis indicated that PsTOE3 directly regulated PsEBB1 by binding to its promoter, and the specific binding site was a C-repeat (ACCGAC). Ectopic expression in Arabidopsis revealed that the PsmiR172b- PsTOE3 module displayed conservative function in regulating flowering. In conclusion, our results provided a novel insight into the functions of PsmiR172-PsTOE3 and possible molecular mechanism underlying bud dormancy release in tree peony.

Acknowledgements

This work was supported by grants from National Natural Science Foundation of China (31872145 and 31972452) and the National Key R&D Program of China (2018YFD1000403). The funding bodies had no role in the design of the study, the collection, analysis, and interpretation of data, or in writing the manuscript. The authors would like to thank MJEditor (www.mjeditor.com) for providing English editing services during the preparation of this manuscript.

Author contributions

G.S. and Z.Y. conceived and designed the experimental plan. W.Y., G.L., and N.D conducted the experiments. Z.Y., Y.Y. and Z.X. analyzed the data. Z.Y., L.C., and G.S. prepared and revised the manuscript. All authors have reviewed and approved the final manuscript.

Data availability

The sequence data that support the findings of this study are available in the NCBI and TAIR databases with the following accession numbers: PsTOE3 (KJ777535), PsEBB1 (OP095871), PsEBB3 (OP095872), PsCYCD (OP095873), PsBG6 (OP095874), AtCYCD1;1 (AT1G70210.1),AtCYCD2;1 (AT2G22490.2),AtCYCD3;1 (AT4G34160.1), AtCYCD3;3 (AT3G50070.1), AtCYCD4;1 (AT5G65420.3), AtCYCD7;1 (AT5G02110.1), AtSOC1 (AT2G45660.1), AtFT (AT1G65480.2), AtLFY (AT5G61850.2).

Conflict of interest

The authors declare no competing interests.

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