Shoot branching involves the coordinated regulation of the activity of meristems established in the axils of leaves along the stem (Mcsteen and Leyser, 2005). Once established, such axillary meristems often arrest as a dormant bud after the production of a few leaves. The hormone auxin, produced in the shoot apex, plays a central role in this process by moving downward in the stem and maintaining these axillary meristems in an inactive state, a process termed apical dominance (Morris, 1977, Snow, 1925, 1929). Since auxin does not itself enter the buds, the auxin transport canalisation model for bud regulation was postulated (Li and Bangerth, 1999; Bennett et al. 2006). According to this model, each bud, acting as an auxin source, must establish canalised auxin export in order to grow. The hormone self-reinforces its transport through positive feedback between flux and auxin transporter accumulation on the membrane of cells in the direction of flux (Sachs, 1969; Mitchison, 1980, 1981). Auxin largely relies on a series of active transporters, including of the PIN-FORMED (PIN) family for its directional cell-cell movement (Gälweiler et al., 1998; Bennett et al., 2014). Depending on the relative strengths of auxin sink in the stem and sources in the buds, and the level of feedback between auxin flux and transporter accumulation, some axillary buds might be able to activate while others would not (Prusinkiewicz et al., 2009).

 第一段 

（p.s. 本文属于Letter，主要的发现是拟南芥花序伴细胞中胼胝质的积累会影响腋芽生长，但是具体机制并不清楚。）