Abstract
In most dicots, lateral roots (LRs) are initiated from the root pericycle cells and their formation is regulated by intrinsic hormones and environmental factors. In Arabidopsis, several Aux/IAAs and two Auxin Response Factors (ARF7 and ARF19) regulate LR formation through controlling auxin signaling. We have shown that Lateral Organ Boundaries-domain 16/Asymmetric Leaves2-like 18 (LBD16/ASL18) and LBD29/ASL16 genes act for LR formation as direct targets of ARF7/19 (Okushima et al., 2007). Arabidopsis genome has 42 LBD/ASL family members that encode putative transcription factors. No obvious phenotypes of the knockout mutant of LBD16, lbd16-1, suggested functional redundancy of auxin-inducible LBD/ASL members for LR formation. In this study, we focused on the auxin-inducible LBD/ASL proteins and analyzed multiple mutants of them to reveal the molecular mechanisms of auxin-regulated LR formation.
