Figure 1. Development of the Arabidopsis root epidermis.

Low-magnification images of root tips from Arabidopsis seedling roots showing the series of developmental events that occur from undifferentiated cells (bottom) to mature cells (top). Left: The three major zones of developmental activities are indicated. Scale bar: 100 µm. Right: A root expressing the non-hair cell marker GL2::GUS illustrates the file-specific pattern of developing hair cell files (unstained; indicated as “H”) and non-hair cell files (blue-stained cells). Major epidermal differentiation events are indicated, together with a list of genes known to be involved in each event. Scale bar: 50 µm.