Abstract
In higher plants, the development of a root system depends on both the maintenance of the root meristem activity and the ability to produce new lateral roots (LRs) and adventitious roots. Molecular genetic studies using Arabidopsis mutants have revealed that 1) SHORT-ROOT and SCARECROW genes regulate the radial patterning of ground tissues in the root meristem, and that 2) auxin signaling mediated by two families of transcriptional regulators, Aux/IAAs and ARFs (Auxin Response Factors) is necessary for LR formation. Analysis of the mutants defective in LR formation (solitary-root and arf7 arf19 mutants) indicated that SLR/IAA14, ARF7, and ARF19 regulate LR initiation via activation of several LBD (LATERAL ORGAN BOUNDARIES-DOMAIN)/ASL (ASYMMETRIC LEAVES2-LIKE) genes, encoding nuclear proteins. In addition, PICKLE-mediated chromatin remodeling is involved in auxin-mediated LR formation. I will introduce the recent model of LR formation in higher plants, particularly in Arabidopsis.
