Quantitative dynamics of auxin signaling proteins in Marchantia polymorpha
Auxin is one of the most important hormones for growth and development of plants. This hormone is perceived by a receptor protein present in the nucleus of plant cells. Auxin perception by its receptor triggers activation of plant growth-related genes by a family of transcription factor proteins called AUXIN RESPONSE FACTORS (ARFs). At low auxin concentrations in cell, activation of growth-related genes is prevented by a repressor protein that prevent ARF function.
In my research, I quantified the natural concentration of auxin receptor, ARF transcription factor and the repressor protein of auxin signaling in the liverwort plant Marchantia polymorpha. I found a dynamic regulation of protein concentration during different stages of plant growth. I also observed that ARF proteins are naturally degraded when they are monomeric while in the dimeric ARFs are protected from degradation. This selective degradation of ARF monomers is required for optimal auxin response and plant growth.