Behavior and possible function of Arabidopsis BES1/BZR1 homolog 2 in brassinosteroid signaling

Two key transcription factors (TFs) in brassinosteroid (BR) signaling BRASSINOSTEROID INSENSITIVE 1-EMS-SUPPRESSOR 1 (BES1) and BRASSINAZOLE RESISTANT 1 (BZR1), belong to a small family with four BES1/BZR1 homologs (BEH1-4). To date, in contrast to the wealth of knowledge regarding BES1 and BZR1, little is known about BEH1-4. Here, we show that BEH2 was expressed preferentially in the roots and leaf margins including serrations, which was quite different from another member BEH4, and that BRs downregulated BEH2 through a module containing GSK3-like kinases and BES1/BZR1 TFs, among which BES1, rather than BZR1, contributed to this process. In addition, BEH2 consistently existed in the nucleus, suggesting that its subcellular localization is not under BR-dependent nuclear-cytoplasmic shuttling control. Furthermore, gene ontology analysis on RNA-seq data indicated that BEH2 may be implicated in stress response and photosynthesis. These findings might assist in the future elucidation of the molecular mechanisms underlying BR signaling.

Automated summary

The study found that BEH2 was highly expressed in the roots and leaf margins, which was significantly different from another member BEH4. BRs downregulated the expression of BEH2 through a module containing GSK3-like kinases and BES1 transcription factors, with BES1 playing a more important role in this process than BZR1. BEH2 consistently existed in the nucleus and its subcellular localization was not controlled by BR-dependent nuclear-cytoplasmic shuttling. Furthermore, gene ontology analysis suggested that BEH2 may be involved in stress response and photosynthesis.