It is well known that the apical part of the stem inhibits axillary bud outgrowth during the vegetative growth period. This phe- nomenon is mostly interpreted in terms of apical dominance (Dun et al., 2006). After apical dominance release, apical axillary buds generally break (Ferguson and Beveridge, 2009). It is well estab- lished that three classes of phytohormones (auxins, cytokinins and strigolactones) are implicated in the activity of axillary buds (see Domagalska and Leyser, 2011 for a recent review). Even if the mechanism is still a matter of debate, it is understood that auxin synthesized in the growing apex moves basipetally in the polar auxin transport stream and inhibits axillary bud outgrowth.