Regulation of lateral root formation by auxin signaling in Arabidopsis

Abstract

In higher plants, lateral root (LR) formation is a major contributor to root architecture in the soil. Although it is well known that auxin promotes LR formation, the molecular mechanisms that regulate auxin-mediated LR formation are still largely unknown. Recent molecular genetic studies using Arabidopsis mutants have shown that normal auxin signaling mediated by two families of transcriptional regulators, Aux/IAAs (Auxin/Indole-3-Acetic Acid; repressors of auxin-responsive transcription) and ARFs (Auxin Response Factor; activators or repressors of auxin-responsive transcription), is necessary for LR formation. Auxin-responsive transcription mediated by SLR/IAA14 and ARF7/ARF19 in the root pericycle is particularly important for LR initiation. This review summarizes what is known about the auxin signaling that regulates LR formation in Arabidopsis, and discusses the role of Aux/IAAs and ARFs for LR initiation and subsequent primordial development.