Abstract
Auxin regulates a bewildering array of processes during plant growth and development. This complexity is belied by the apparent simplicity of the auxin-signaling pathway. Auxin regulates transcription via the TIR1/AFB-Aux/IAA-ARF pathway. The hormone directly promotes Aux/IAA degradation through the action of SCFTIR1/AFB thus permitting ARF-dependent transcription. In the case of the TIR1/AFB proteins, recent results indicate that different members of the family have distinct activities both with respect to auxin binding and Aux/IAA interaction. We are currently exploring the possibility that these differences contribute to the complexity of auxin response. We are also studying the evolutionary history of auxin signaling. Our results indicate that the mechanism of auxin signaling is conserved in land plants.
