Downregulation of lncRNA PpL-T31511 and Pp-miRn182 Promotes Hydrogen Cyanamide-Induced Endodormancy Release through the PP2C-H2O2 Pathway in Pear (Pyrus pyrifolia).

Liang Li,Jinhang Liu,Chao Wang,Yongyu Li,Qin Liang,Yu Feng,Shaohua Wu

doi:10.3390/ijms222111842

Abstract

Bud endodormancy is an important, complex process subject to both genetic and epigenetic control, the mechanism of which is still unclear. The endogenous hormone abscisic acid (ABA) and its signaling pathway play important roles in the endodormancy process, in which the type 2C protein phosphatases (PP2Cs) is key to the ABA signal pathway. Due to its excellent effect on endodormancy release, hydrogen cyanamide (HC) treatment is considered an effective measure to study the mechanism of endodormancy release. In this study, RNA-Seq analysis was conducted on endodormant floral buds of pear (Pyrus pyrifolia) with HC treatment, and the HC-induced PP2C gene PpPP2C1 was identified. Next, software prediction, expression tests and transient assays revealed that lncRNA PpL-T31511-derived Pp-miRn182 targets PpPP2C1. The expression analysis showed that HC treatment upregulated the expression of PpPP2C1 and downregulated the expression of PpL-T31511 and Pp-miRn182. Moreover, HC treatment inhibited the accumulation of ABA signaling pathway-related genes and hydrogen peroxide (H2O2). Furthermore, overexpression of Pp-miRn182 reduced the inhibitory effect of PpPP2C1 on the H2O2 content. In summary, our study suggests that downregulation of PpL-T31511-derived Pp-miRn182 promotes HC-induced endodormancy release in pear plants through the PP2C-H2O2 pathway.

Highlights

To cope with cyclic periods of environmental stress such as cold winters, perennial deciduous trees developed a strategy of going dormant during evolution [1]
The results showed that hydrogen cyanamide (HC) treatment effectively stimulated endodormancy release and floral bud breakage in pear plants (Figure 1b)
It was noted in the experiment that some pear floral buds began to expand, and even proceeded to burst, under HC treatment after 9 days

Summary

Introduction

To cope with cyclic periods of environmental stress such as cold winters, perennial deciduous trees developed a strategy of going dormant during evolution [1]. Perennial deciduous trees shed leaves, and the buds enter endodormancy, which is induced by cold temperatures, short photoperiods or both [3,4]. The release of buds from endodormancy is a temperature-dependent process, where a genetically determined amount of accumulative chilling is required to break endodormancy [6]. The endodormant buds cannot break endodormancy under insufficient chilling accumulation during winter, which leads to unsuccessful flowering and reduced fruit production [7]. When this chilling requirement is met, pear buds shift to ecodormancy. Identifying the molecular mechanism regulating endodormancy may provide the basis for solving this key problem in agriculture

Methods

Results

Discussion

Conclusion