Dissecting the role of rapid auxin responses in plant morphogenesis

Introduction

Plant cells, living in their cell walls, are immobile and thus tightly control growth to shape their organs and bodies. Mechanical properties of the cell wall are modulated by pH, which is governed by the activity of plasma membrane proton ATPases. The central regulator of plant growth, phytohormone auxin, regulates gene transcription.

Recent Discoveries

My team and I have significantly contributed to recent discoveries of additional auxin signaling pathways that act rapidly, in a non-genomic manner. Surprisingly, all auxin signaling pathways converge on the regulation of ion fluxes and cell wall pH.

Central Hypothesis

The central hypothesis of the MORpH project is that the rapid regulation of cell wall pH by auxin plays a fundamental role in plant development. I propose that rapid auxin responses controlled by the TIR1/AFB auxin receptors participate in the morphogenesis of the above-ground plant body and that these receptors also drive rapid responses in grasses.

Project Goals

In this project, I will:

1. Reveal the identity of molecular components of the AFB1-driven cytoplasmic auxin pathway using a forward genetic screen and protein proximity labeling approaches, exploiting the unique genetic material of my team.
2. Address the role of the rapid cytoplasmic auxin responses in the development of above-ground organs of the Arabidopsis model plant.
3. Embrace a new model system relevant to cereals, Brachypodium distachyon, to elucidate the significance of rapid auxin responses in grasses.
4. Analyze and manipulate cell wall pH dynamics during key plant morphogenetic events using a combination of live-cell imaging, proteomics, and genetics, and discover the regulatory mechanisms underlying cell wall acidification.

Conclusion

The MORpH project will uncover novel fundamental roles of rapid auxin signaling in morphogenesis, and at the same time will expand my research toward plant models relevant to cereal crops.