Lateral Root Initiation and Development

Lateral root primordia originate from the mature pericycle of the parent root. One of the first events is a periclinal division that generates a double layer of pericycle-derived cells. Cells of the primordia begin to differentiate almost immediately after initiation, as evidenced by differential gene expression in the inner and outer layers.

Lateral root primordia develop through a characteristic program of cell divisions and expansions to create a fully patterned structure that resembles the primary root tip.

After the lateral root primordium is formed, it becomes a mature lateral root by a two stage process. First, the primodium emerges through the overlaying tissues by cell expansion. The increase in cell size is particularly apparent in cells near the base of the primordium, while cell number remains relatively unchanged. Second, the new lateral root begins to elongate, and cell numbers increase at the root tip. This is characteristic of mature root elongation via division of cells in the root apical meristem.

-- Relevent Publication --
Organization and cell differentiation in lateral roots of Arabidopsis thaliana.
Malamy JE and Benfey PN.
Development. 1997 Jan;124(1):33-44. link | pdf