Phytochrome B and REVEILLE1/2-mediated signalling controls seed dormancy and germination in Arabidopsis.

Zhimin Jiang,Yanjun Jing,Weijiang Tang,Rongcheng Lin,Gang Xu

doi:10.1038/ncomms12377

Abstract

Seeds maintain a dormant state to withstand adverse conditions and germinate when conditions become favourable to give rise to a new generation of flowering plants. Seed dormancy and germination are tightly controlled by internal and external signals. Although phytochrome photoreceptors are proposed to regulate primary seed dormancy, the underlying molecular mechanism remains elusive. Here we show that the REVEILLE1 (RVE1) and RVE2 transcription factors promote primary seed dormancy and repress red/far-red-light-reversible germination downstream of phytochrome B (phyB) in Arabidopsis thaliana. RVE1 and RVE2 expression is downregulated after imbibition and by phyB. RVE1 directly binds to the promoter of GIBBERELLIN 3-OXIDASE 2, inhibits its transcription and thus suppresses the biosynthesis of bioactive gibberellins. In addition, DELAY OF GERMINATION 1 also acts downstream of phyB. This study identifies a signalling pathway that integrates environmental light input with internal factors to control both seed dormancy and germination.

Highlights

Seeds maintain a dormant state to withstand adverse conditions and germinate when conditions become favourable to give rise to a new generation of flowering plants
We identified RVE1 and RVE2 as activators of seed dormancy and further provided molecular and genetic evidence to show that RVE1 and RVE2 promote primary seed dormancy and repress red/far-red-light-mediated germination downstream of phytochrome B (phyB) in A. thaliana
We found that the transcription of RVE1, RVE2 and DELAY OF GERMINATION 1 (DOG1) is reduced by phyB-Pfr, the active form of phyB

Summary

Introduction

Seeds maintain a dormant state to withstand adverse conditions and germinate when conditions become favourable to give rise to a new generation of flowering plants. We show that the REVEILLE1 (RVE1) and RVE2 transcription factors promote primary seed dormancy and repress red/far-red-light-reversible germination downstream of phytochrome B (phyB) in Arabidopsis thaliana. This study identifies a signalling pathway that integrates environmental light input with internal factors to control both seed dormancy and germination. Light-activated phyB interacts with and promotes the degradation of a negative regulator, PHYTOCHROME-INTERACTING FACTOR 1 (PIF1, known as PIL5)[36,37]. We identified RVE1 and RVE2 as activators of seed dormancy and further provided molecular and genetic evidence to show that RVE1 and RVE2 promote primary seed dormancy and repress red/far-red-light-mediated germination downstream of phyB in A. thaliana. We reveal a genetic pathway that links light input with internal factors to control seed dormancy and germination that can potentially optimize seed adaptability to changing environments

Methods

Results

Conclusion