Figure 6.

Interactions between auxin and the MAX pathway. Regulatory signals represented in blue were investigated in this study. Step 1, Auxin traveling in the PATS promotes MAX3 and MAX4 expression in an AXR1-dependent manner, prevented if IAA12 is stabilized. Step 2, Auxin-promoted MAX3 and MAX4 transcript levels lead to increased strigolactone production, which leads to reduced bud outgrowth and reduced auxin export from buds into the PATS. Step 3, If strigolactones are low, branching is increased and auxin level increases, feedback up-regulating MAX3 and MAX4 to increase strigolactone levels as in step 1. Step 4, Strigolactone signaling may feedback down-regulate transcript levels independent of auxin; the dashed line indicates weak/putative interaction. Step 5, Auxin also down-regulates cytokinin synthesis, and cytokinin promotes branching. The environment/genotype/developmental program may influence each of these regulatory stages tissue specifically. [See online article for color version of this figure.]