Stress-induced plasma membrane remodeling in Arabidopsis thaliana roots

Plant roots are constantly exposed to fluctuating soil environments, such as the presence of pathogens or suboptimal growth conditions like nutrient deficiency. Tuning the trade-off between growth and defence is key to survival. At the cellular level, sensors embedded in the plasma membrane (PM) survey changes in their surroundings. Thus, the PM forms the first active cell barrier in multicellular organisms - the site where external signals are perceived and transduced into the cell. This is enabled by the fascinating molecular organization of billions of PM components in an asymmetric lipid bilayer with integral and associated proteins organized into co-existing membrane domains. However, the roles of individual molecules, their interplay with other lipids and proteins, nanodomain formation and persistence are understudied. This PhD research investigates how membrane domains evolve during stress signalling in Arabidopsis thaliana roots, using the interaction between the endogenous peptide family of Plant Elicitor Peptides (PEPs) and their receptors PEPR1 and PEPR2 as a model system. The PEP-PEPR system is a well-characterized danger-triggered pathway in Arabidopsis, linking stress detection with damage repair. But little is known about whether and how the receptor interacts with other PM components to uncouple and finely coordinate different PEP-induced responses, namely defence amplification, root hair formation and primary root growth inhibition. Intriguingly, the questions that come to mind are: Is the specificity of PEP-induced output dependent on PEPR-nanodomain formation in the PM? If so, what is the composition of the PEPR nanodomain and how does it reorganize perceiving danger signals? And what is the physiological consequence of altering the PEPR nanodomain and its associated components? In this PhD thesis, I will study the spatiotemporal alterations in the plasma membrane during endogenous stress perception and its functional relevance in roots using a combination of proteomics, lipidomics, high-resolution live-cell imaging and computational biology. Coupled with future studies about analogous pathways in commercially important crops, such as tomatoes, it is a stepping-stone to uncover strategies to engineer immune responses in roots without compromising crop yield. Understanding plant stress resilience is essential to secure food by making crops more adaptable to severe environmental conditions.