Abstract
In higher plants, the development of a root system depends on the ability to produce new lateral roots (LRs) and adventitious roots. Molecular genetic studies using Arabidopsis mutants have revealed that auxin signaling mediated by two families of transcriptional regulators, Aux/IAAs and Auxin Response Factors (ARFs), is necessary for LR formation. Our previous analysis of the mutants defective in LR formation (solitary-root/iaa14, crane/iaa18 and arf7 arf19 mutants) indicated that several Aux/IAAs and ARF7/19 regulate LR initiation via activation of several auxin-inducible LBD (LATERAL ORGAN BOUNDARIES-DOMAIN)/ASL (ASYMMETRIC LEAVES2-LIKE) genes (LBD16/ASL18, LBD29/ASL16), encoding nuclear proteins. To understand the molecular mechanisms that regulate auxin-mediated LR formation in Arabidopsis, we are now analyzing the downstream genes of LBD16/ASL18. In this symposium, our auxin signaling pathway model for LR formation will be discussed.
