REKSARD: Receptor-like Kinase Signalling in Arabidopsis thaliana Root Development

The past decade researchers have mainly focused on the analyses of phytohormone gradients and mobile transcription factors to explain patterning. In Arabidopsis, model processes like primary and lateral root development are well understood on the level of transcriptional changes and hormonal control, but very little attention has been given to an alternative way of cell-cell communication using ligand-receptor-like kinase systems (De Smet et al., 2009, Nat Cell Biol, in press). Lately a number of receptor-like kinases and potential ligands have been described in root development (De Smet et al., 2008, Science 322:494-497; Müller et al., 2008, Plant Cell 20:934-946; Stahl et al., 2009, Curr Biol 19:909-14), making it a perfect time to start investigating how these receptor-like kinases and their respective ligands control the different developmental processes and what their targets are. More and more tools become available to study difficult membrane proteins on the level of 3D structure, phosphoproteomics, and in silico ligand identification. In brief, I will use different and interdisciplinary strategies, based on state of the art transcriptomics, proteomics, interactomics, associomics and more in depth analysis on the single gene/protein/ligand level to describe ligand-receptor-mediated cell-cell communication during root development, and, more specifically, to identify key components in ACR4-dependent signalling. The aspects this project plans to address would contribute extensively to the knowledge of membrane associated receptors-like kinases in general, have rarely been covered focusing on one receptor-like kinase, and will allow elucidating the mechanisms and structural aspects behind this crucial ACF4-dependent signaling pathway, such as: (1) identification of downstream genome-wide transcriptional changes, (2) identification of substrates on a proteome-wide scale, and (3) identification and physical interaction of ligands with the receptor domain.