Fig. 2

Key cellular and morphological changes during lateral root initiation and development. The first visible step in lateral root morphogenesis involves the asymmetric expansion of lateral root founder cells (LRFCs) and the migration of their nuclei toward the common cell wall. This is followed by an asymmetric anticlinal division, resulting in the formation of a stage I lateral root primordium (LRP). Auxin signalling within the LRFCs and endodermis, along with localized rearrangements of cortical microtubules (CMTs) and actin microfilaments, play crucial roles in facilitating the asymmetric radial expansion and division of LRFCs. The establishment of the quiescent center occurs during the developmental phase transition of the LRP at stage IV, coinciding with the transition from a flat-topped to a dome-shaped primordium as it crosses the endodermis. LRP finally breaks through the overlying cortex and epidermis cells to emerge from the main root