Temperature and Force as Modulators of AUXIN RESPONSE FACTOR Condensation and Stability

Abstract

The hormone auxin is a singular molecule which massively influences plant growth and development and must be tightly regulated. Plants utilize a swath of auxin signaling proteins to maintain proper auxin regulation. This work delves into the role of two transcription factors in the auxin signaling pathway, AUXIN RESPONSE FACTOR 7 and AUXIN RESPONSE FACTOR 19. First we investigate the relationship between elevated temperatures and the ARFs to describe a new mechanism by which ARF proteins integrate temperature signals into a physiological response. This work highlights the role of both condensation and protein stability in this response. Then, we describe how natural variation within Arabidopsis thaliana can be harnessed to better understand this ARF thermal stability and uncover a potential role of the protein DANGEROUS MIX 1 on this response. Finally, we explore factors which influence ARF condensation under non-equilibrium conditions. Observations in this work are used as inspiration for new biophysical modeling which provide an in vivo proof of concept of motility influenced phase separation, generally. This work thus advances our understanding of the auxin response pathway by describing new roles of temperature and active force on AUXIN RESPONSE FACTOR condensation and stability.