This paper describes how the plant hormone auxin regulates the degradation of AUX/IAA proteins through the SCF(TIR1) ubiquitin ligase complex. The study shows that auxin promotes the degradation of AUX/IAA proteins by enhancing their interaction with SCF(TIR1). This interaction is mediated by domain II of the AUX/IAA proteins, and mutations in this domain prevent the interaction, leading to increased protein stability. The study also demonstrates that the stability of AUX/IAA proteins is affected by mutations in the SCF(TIR1) complex, with recessive mutations increasing protein stability and dominant mutations decreasing it. Auxin treatment leads to the degradation of AUX/IAA proteins, which is blocked by proteasome inhibitors. The study further shows that the stability of AUX/IAA proteins is regulated by the ubiquitin-proteasome pathway, with the SCF(TIR1) complex playing a key role in their degradation. The findings suggest that auxin promotes the degradation of AUX/IAA proteins, leading to the derepression of auxin response pathways. The study also highlights the importance of domain II in the interaction between AUX/IAA proteins and SCF(TIR1), and how this interaction is regulated by auxin. The results provide a mechanistic understanding of how auxin regulates plant development through the degradation of AUX/IAA proteins.This paper describes how the plant hormone auxin regulates the degradation of AUX/IAA proteins through the SCF(TIR1) ubiquitin ligase complex. The study shows that auxin promotes the degradation of AUX/IAA proteins by enhancing their interaction with SCF(TIR1). This interaction is mediated by domain II of the AUX/IAA proteins, and mutations in this domain prevent the interaction, leading to increased protein stability. The study also demonstrates that the stability of AUX/IAA proteins is affected by mutations in the SCF(TIR1) complex, with recessive mutations increasing protein stability and dominant mutations decreasing it. Auxin treatment leads to the degradation of AUX/IAA proteins, which is blocked by proteasome inhibitors. The study further shows that the stability of AUX/IAA proteins is regulated by the ubiquitin-proteasome pathway, with the SCF(TIR1) complex playing a key role in their degradation. The findings suggest that auxin promotes the degradation of AUX/IAA proteins, leading to the derepression of auxin response pathways. The study also highlights the importance of domain II in the interaction between AUX/IAA proteins and SCF(TIR1), and how this interaction is regulated by auxin. The results provide a mechanistic understanding of how auxin regulates plant development through the degradation of AUX/IAA proteins.