Functional dissection of transcription factor phase separation in plant hormone response.

The phytohormone auxin plays an important role in virtually every developmental process that comprise the plant life cycle. Auxin Response Factors (ARFs) regulate transcription of auxin responsive genes and are therefore essential components of the auxin signalling pathway. ARFs are subdivided into three classes, A, B, and C each with distinct functional characteristics. Class A ARFs are generally viewed as transcriptional activators of auxin responsive genes, whereas class B and C ARFs repress these genes. Class A and B ARFs act antagonistically, by competing for the same DNA binding sites. Their relative abundance and stoichiometry are therefore important determinants of auxin-mediated transcriptional output. During this project we investigate how class A and B ARF concentrations are controlled in planta, using the model organism Marchantia polymorpha. We dive into the phenomena of condensate formation (high local protein concetrations) due to Liquid-Liquid phase separation, which is exhibite by ARFs in vivo, and protein degradation. Ultimately, we aim to obtain a better understanding of how ARF levels are regulated.