Lateral root initiation pathway

The lateral root initiation pathway is a fundamental biological process in plants responsible for the formation of secondary roots from the pericycle layer of the primary root (8, 12). It is primarily regulated by the phytohormone auxin, which creates local maxima to trigger asymmetric anticlinal cell divisions and subsequent organogenesis (5, 13). Key molecular components include TIR1/AFB receptors, Aux/IAA repressor proteins, and Auxin Response Factors (ARFs) such as ARF7 and ARF19, which activate downstream targets like LBD16 and GATA23 (7, 12). While this pathway is not a therapeutic target for human disease, it is of significant interest in agriculture for optimizing root architecture and nutrient uptake efficiency (3). Pathogenic organisms, such as the fungus Ustilago maydis, have been shown to hijack this pathway to induce galls in host tissues (2). Chemical intervention typically involves the use of auxin analogs or transport inhibitors, such as NPA and TIBA, to modulate root branching and development (11).

Other names

Auxin-mediated lateral root initiationLateral root formation pathwayLR initiationLateral root development pathway

The pathway is activated by auxin binding to the TIR1/AFB F-box proteins within the SCF E3 ubiquitin ligase complex, which triggers the degradation of Aux/IAA transcriptional repressors (5, 8). This releases ARF transcription factors (e.g., ARF7, ARF19) to promote the expression of genes such as LBD16 and GATA23, which are essential for the first formative cell divisions in the xylem-pole pericycle (7, 12).