Interplay between REVEILLE1 and RGA-LIKE2 regulates seed dormancy and germination in Arabidopsis

Abstract

Environmental light signal and GAs synergistically regulate seed dormancy and germination. The phytochrome B (phyB) photoreceptor regulates expression of the REVEILLE1 (RVE1) transcription factor, which directly inhibits GIBBERELLIN 3-OXIDASE2 transcription, suppressing GA biosynthesis. However, whether phyB-RVE1 coordinates with GA signaling in controlling seed dormancy and germination remains unknown. Here, we demonstrate that RVE1 regulation of seed dormancy and germination requires a DELLA repressor, REPRESSOR OF GA-LIKE2 (RGL2), in Arabidopsis thaliana. RVE1 interacts with both RGL2 and its E3 ubiquitin ligase SLEEPY1 (SLY1) and promotes RGL2 stability by restraining the RGL2–SLY1 interaction. Furthermore, RVE1 and RGL2 synergistically regulate global transcriptome changes; RGL2 enhances the DNA-binding capacity and transcriptional activity of RVE1 in regulating downstream gene expression. Moreover, RGL2 expression is repressed by phyB. Our study reveals a novel regulatory mechanism in which the RVE1–RGL2 module coordinately controls seed dormancy and germination by integrating light perception, GA metabolism and GA signaling pathways.