Deciphering RLP44-linked LRR-receptor dynamics and signalling specificity at the plasma membrane

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To integrate external cues with intrinsic developmental programs, plants rely on an expanded contingent of cell surface receptors. The largest and best characterized group of these receptors is formed by the leucine-rich-repeat receptor-like kinases (LRR-RLK), which perceive a wide variety of developmental and pathogen defence-related cues. LRR-RLKs form an extensive interaction network, which raises the central question of how distinct signalling responses can be achieved. Spatial organisation of the plasma membrane, modification and regulated trafficking of receptor proteins, as well as cell wall association have all been proposed to be involved in controlling signalling. However, it is unclear how these processes intersect to spatially and temporally modulate plasma membrane receptor dynamics and signalling outputs. Recently, we have revealed that the cell wall-binding protein RLP44 is able to interact with two different LRR-RLK receptor complexes and modulate their respective signalling activities. Thus, the complex interplay of RLP44-linked signalling pathways represents an ideal system to unravel how specificity is achieved within the LRR-RLK interaction network. In this project, we aim to decipher the spatial and temporal coordination of RLP44-associated pathways. To this end, we will quantify dynamics of RLP44 and its ligand-binding interaction partners in the plasma membrane using super-resolution microscopy and unravel the role of posttranslational modification and membrane trafficking in controlling RLP44-associated signalling. In particular, we are interested in the relevance of cell wall binding in controlling internalization of RLP44 as well as in determining the interactions it engages in. We expect from this project novel insight into the integration and coordination of the multitude of signalling pathways within the LRR-RLK network.