Affiliation:
1. Shaanxi Key Laboratory of Qinling Ecological Intelligent Monitoring and Protection, School of Ecology and Environment Northwestern Polytechnical University Xi'an 710129 China
2. Research & Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518057 China
3. Shaanxi Fundamental Science Research Project for Chemistry & Biology the College of Life Sciences, Northwest University Xi'an 710127 China
Abstract
Summary
Abscisic acid (ABA) and gibberellins (GA) antagonistically mediate several biological processes, including seed germination, but the molecular mechanisms underlying ABA/GA antagonism need further investigation, particularly any role mediated by a transcription factors module.
Here, we report that the DELLA protein RGL2, a repressor of GA signaling, specifically interacts with ABI4, an ABA signaling enhancer, to act as a transcription factor complex to mediate ABA/GA antagonism.
The rgl2, abi3, abi4 and abi5 mutants rescue the non‐germination phenotype of the ga1‐t. Further, we demonstrate that RGL2 specifically interacts with ABI4 to form a heterodimer. RGL2 and ABI4 stabilize one another, and GA increases the ABI4‐RGL2 module turnover, whereas ABA decreases it. At the transcriptional level, ABI4 enhances the RGL2 expression by directly binding to its promoter via the CCAC cis‐element, and RGL2 significantly upregulates the transcriptional activation ability of ABI4 toward its target genes, including ABI5 and RGL2. Abscisic acid promotes whereas GA inhibits the ability of ABI4‐RGL2 module to activate transcription, and ultimately ABA and GA antagonize each other. Genetic analysis demonstrated that both ABI4 and RGL2 are essential for the activity of this transcription factor module.
These results suggest that the ABI4‐RGL2 module mediates ABA/GA antagonism by functioning as a double agent.
Funder
National Natural Science Foundation of China
China Postdoctoral Science Foundation
Basic and Applied Basic Research Foundation of Guangdong Province