Brassinosteroid perception in the epidermis controls root meristem size.

This work provides further insights into poorly understood mechanisms that coordinate growth between cell layers and tissues in plants. Many lines of evidence (e.g. periclinal chimeras) indicate that the contribution of specific cell lineages to the developing plant is remarkably plastic, suggesting the existence of non-cell autonomous mechanisms to coordinate growth between cell layers. In a recent series of experiments, Hacham et al. provide further evidence for one such mechanism, in which the perception of brassinosteroid in the epidermis regulates the growth of more internal layers.