Epidermal pattern formation in the root and shoot of Arabidopsis.

Root hair formation, stomata development on hypocotyls and trichome formation on leaves in Arabidopsis represent three model systems for epidermal patterning in plants that involve a common set of genes or corresponding homologues. The resulting pattern and the developmental readout are, however, strikingly different. Trichomes become regularly spaced on the leaf surface. Root hairs and stomata-bearing cells are formed in rows at specific locations with reference to the underlying cortex cells. In this review, we summarize the mechanistic similarities and discuss differences that might account for the different outcome of patterning in each system.