Figure 2.

Selected components of axillary bud outgrowth regulation. Red light (R) promotes branching through phyB and SPL9/15 that regulate BRC1 (note FR is far-red light). Light quality also reduces ABA level, and increases sugar content, which suppresses BRC1 expression. Nutrient availability positively regulates CK content but negatively regulates SL production. SLs are transported at least partly by PDR1 and are perceived by the DAD2-MAX2-D53 complex. The degradation of D53 triggers BRC1 expression that inhibits axillary bud outgrowth. There are likely BRC1 independent pathways that involve T6P and SL and CK signaling. The arrows and blunt lines represent positive and negative regulation respectively.