The lateral root cap acts as an auxin sink that controls meristem size (Curr Biol)

During root growth, cellular activities need to be coordinated across tissues. Mambro et al. have identified molecular mechanisms involved in root apical meristem maintenance by auxin homeostasis regulation in lateral root cap (LRC) cells. The cytokinin response regulator ARR1 regulates expression of the auxin transporter PIN5 and an auxin conjugating amidoacyl transferase, GH3-17, in LRC. PIN5 maintains auxin levels by exporting auxin in to the endoplasmic reticulum, and GH3-17 possibly conjugates IAA with glutamate. Altering the expression of PIN5 and GH3-17 alters root meristem size.  Thus the authors have shown the significance of auxin homeostasis by cytokinin signaling in LRC for root meristem size and root development. (Summary by Suresh Damodaran) Curr. Biol. 10.1016/j.cub.2019.02.022.