Fig. 6.

A proposed model for the effect of ABA on BR signaling outputs. For BR signaling pathway, BR binding to BRI1 activates BRI1 complex via releasing plasma membrane association of BKI1, association with BAK1, and phosphorylation of BSKs. Activated BRI1 complex likely inhibits BIN2 kinase through yet an unknown mechanism, leading to the dephosphorylation of BES1, which actively regulates BR-responsive gene expression. ABA could regulates unknown components downstream of BRI1, but upstream of BIN2 in the BR signaling, which then lead to the activation of BIN2 through an undiscovered mechanism. Gain-of-function mutation of ABI1 and ABI2 in the ABA early signaling can inhibit the effect of ABA on BR signaling.