Auxin Response Factor Proteolysis

The signaling molecule auxin controls nearly all aspects of plant development, largely through transcriptional networks. Central to these networks are Auxin Response Factor (ARF) proteins. These transcription factors tune the expression of auxin responsive gene sets. Through the work presented in this thesis we discovered that post translational stability of certain ARF proteins of the liverwort Marchantia polymorpha are regulated by degradation through the 26S proteasome. Based on this observation, we retraced the evolutionary origins of this instability, mapped the molecular mechanisms required for degradation, and assessed its functional and developmental relevance. We show that ARF degradation by the proteasome is ancient, deeply conserved, and crucially important for protein function and plant development.