Brassinosteroids (BRs) signal through plasma membrane-localized receptor BRI1 and other components including negatively acting BIN2 kinase to regulate BES1/BZR1 family transcription factors, which controls the expression of thousands of genes for various BR responses. Recent studies demonstrated that BR regulation of gene expression involves histone-modifying enzymes and changes of chromatin structure. Genomic experiments identified a few thousand BES1/BZR1 target genes, many of which are involved in plant growth and various signaling pathways. Moreover, BES1/BZR1 interact with many transcription factors to integrate BR and other signaling pathways. Finally, in addition to regulating BES1/BZR1, BIN2 can phosphorylate and regulate the activities of more transcription factors and signaling components, providing additional inputs of BR signaling to the BR transcriptional network and points of crosstalk with different pathways.
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