Dissecting mechanisms in root growth from the transition zone perspective

The root of the plant Arabidopsis thaliana is a dynamic structure where cells continuously divide and differentiate to sustain its postembryonic undetermined growth. Cells at different developmental stages are organized in distinguished zone whose position and activities are maintained constant during root growth. In this review, we will discuss latest discoveries on the regulatory networks involved in root zonation and, in particular, in the mechanisms involved in maintaining the position of the transition zone, a root developmental boundary. Developmental boundaries physically divide cells with different functions and identities. The transition zone separates dividing from differentiating cells in two functional domains, preserving their identity during root growth, thus controlling root development.