Abstract
Lateral root (LR) formation is one of the auxin-mediated developmental processes in vascular plants. Physiological and genetic studies using Arabidopsis thaliana and other plant species have revealed the role of auxin biosynthesis, transport and signaling in LR initiation and primordium development. These studies have shown that auxin-regulated transcription through Auxin/Indole-3-Acetic Acid (Aux/IAA) and AUXIN RESPONSE FACTOR (ARF) protein families is important for the developmental steps during LR formation : 1) the IAA28-ARFs module regulates LR founder cell specification, 2) the SOLITARY-ROOT(SLR)/IAA14-ARF7-ARF19 module regulates nuclear migration and asymmetric cell divisions of the LR founder cells for LR initiation, 3) the BODENLOS/IAA12-MONOPTEROS/ARF5 module also regulates LR initiation and organogenesis, and 4) the SHY2/IAA3-ARFs module regulates LR primordium development and LR emergence. This review summarizes recent findings on auxin-mediated LR formation, focusing on the molecular mechanisms of SLR/IAA14-ARF7-ARF19 module-dependent LR initiation.
