In plants, the hormone auxin can trigger fast cellular responses. These respones are evolutionary conserved, yet little is known about how they are generated. This project will compare fast auxin responses in distinct plant species using genetics and biochemistry to identify the key components that generate these responses.
The hormone auxin regulates almost every aspect of plant life. Many auxin responses are transcriptional, while several other auxin responses occur too rapid for transcription to be involved. Importantly, auxin responses must have deep (>700 Million years) evolutionary origins, given that even algae respond to auxin. However, components of known auxin response pathways are lacking in algae. Likewise, no known pathway can account for rapid non-transcriptional responses observed across the plant kingdom.
Aim of the project
In this project, I will address these two problems. I will caplitalise upon recent discoveries from our team, to mechanistically dissect a novel, ancient auxin response pathway. Through comparative phospho-proteomics across algae and land plants, our team recently discovered a deeply conserved and rapid protein phosphorylation response. Interestingly, this response occurs independently of the receptors for gene expression responses, indicating that the auxin signal is perceived by an unknown receptor and represents a novel pathway.
We identified a family of MAP kinases (named MARKs) that are critical for auxin-dependent phosphorylation in two distant plant species, Marchantia polymorpha and Arabidopsis thaliana. MARK kinases have a polymerisation domain and localise to protein condensates (puncta). I hypothesise that MARK associates with auxin receptors and cellular effectors to relay rapid, non-transcriptional responses.
I will merge my expertise in genetic, molecular and biochemical analysis of auxin action with the host’s expertise in comparative evolutionary biology and proteomics cell to:
- Identify the proteins that interact with MARK
- Identify the auxin receptors that are responsible for MARK-pathway activation
- Identify direct targets of MARK phosphorylation and establish the physiological relevance of the pathway
I expect to uncover an entirely novel mechanism underlying evolutionary consereved auxin responses. Studying this overlooked system will open up an entirely new area in plant hormone biology and reveal what is likely the ancestral auxin response system.
Do you have a question about the evolution of auxin-triggered protein phosphorylation, or would you like to join us as a student researcher? Please contact us.