Push-pull strategy in the regulation of postembryonic root development

•Multiple local regulators maintain the integrity of root stem cell niche.•Mobile signals from the stem cell niche affect transit-amplifying cells and beyond.•Top-down signals through vascular system regulate the meristem activity.•Bottom-up and top-down signals coordinate the postembryonic root growth.

Unlike animals, plants continue to grow throughout their lives. The stem cell niche, protected in meristems of shoots and roots, enables this process. In the root, stem cells produce precursors for highly organized cell types via asymmetric cell divisions. These precursors, which are “transit-amplifying cells,” actively divide for several rounds before entering into differentiation programs. In this review, we highlight positive feedback regulation between shoot- and root-ward signals during the postembryonic root growth, which is reminiscent of a “push-pull strategy” in business parlance. This property of molecular networks underlies the regulation of stem cells and their organizer, the “quiescent center,” as well as of the signaling between stem cell niche, transit-amplifying cells, and beyond.