Regulation of the nuclear activities of brassinosteroid signaling

Brassinosteroids (BRs) are important plant growth hormones that largely rely on transcription factors (TFs) to regulate a variety of plant physiological/developmental processes. Past genetic and biochemical studies have identified two key TFs and interacting partners that play major roles in regulating many BR-responsive genes, while genome-wide microarray experiments have discovered at least 50 BR-regulated TFs. However, little is known how these TFs function or whether additional TFs are involved in BR signaling. In the past few years, genetic studies and yeast one/two-hybrid screens coupled with microarray and chromatin immunoprecipitation experiments not only revealed new roles of the key regulatory TFs but also implicated additional TFs and other nuclear proteins in regulating the nuclear activities of BR signaling in Arabidopsis and rice.

Research highlights▶ New roles of BES1 and BIM1 in pollen/anther development and embryogenesis. ▶ Potential functions of ARF2, BRX, and DRN in the auxin–BR crosstalk. ▶ Regulatory roles of atypical and non-canonical bHLH proteins. ▶ Involvement of members of the GRAS, MADS, and MYB families in BR signaling. ▶ BES1-mediated recruitment of other nuclear proteins to regulate plant growth.