摘要
Brassinosteroids(BRs)are plant-specific steroid hormones which regulate plant growth,development,and adaptation.Transcriptional regulation plays key roles in plant hormone signaling.A mediator can serve as a bridge between gene-specific transcription factors and the RNA polymerase machinery,functioning as an essential component in regulating the transcriptional process.However,whether a mediator is involved in BR signaling is unknown.Here,we discovered that Oryza sativa mediator subunit 25(Os MED25)is an important regulator of rice BR signaling.Phenotypic analyses showed that the Os MED25-RNAi and osmed25 mutant presented erect leaves,as observed in BR-deficient mutants.In addition,the Os MED25-RNAi and osmed25 mutant exhibited decreased BR sensitivity.Genetic analysis indicated that Os MED25-RNAi could suppress the enhanced BR signaling phenotype of Osbzr1-D.Further biochemical analysis showed that Os MED25 interacts with Os BZR1 in vivo,and Os MED25 is enriched on the promoter of Os BZR1 target genes.RNA sequencing analysis indicated that Os MED25 affects the expression of approximately 45%of Os BZR1-regulated genes and mainly functions as a corepressor of Os BZR1.Together,these findings revealed that Os MED25 regulates rice BR signaling by interacting with Os BZR1 and modulating the expression of Os BZR1 target genes,thus expanding our understanding of the roles of mediators in plant hormone signaling.
基金
National Natural Science Foundation of China(31671653,31801017,31871591)
National Transgenic Science and Technology Program(2018ZX0800102B)
National Key Research and Development Program of China(2017YFD0100501)
Natural Science Foundation of Heilongjiang Province(C2018064)。
