The importance of peptide signaling for intercellular communication in plants is a fairly recent discovery. Nonetheless, we now know that signaling peptides are involved in numerous developmental processes. The GOLVEN (GLV)/ROOT GROWTH FACTOR (RGF)/CLE-LIKE (CLEL) peptide family has been shown to control different aspects of root development, including lateral root (LR) formation. One of the GLV genes, GLV6, is already expressed in LR founder cells at the onset of the very first asymmetric cell division (ACD) required for correct primordium organogenesis. Furthermore, GLV6 overexpression abolishes the asymmetry of this division, thereby inhibiting the development of LRs. The recent identification of two putative GLV6 receptors constitutes an important step towards the dissection of this signaling pathway. As for most signaling peptides, the intermediate steps between GLV6 perception and the downstream physiological responses remain unknown. To understand how GLV6 regulates the patterning of the first LR founder cell divisions, we propose two complementary approaches. A phosphoproteomics experiment to unravel the rapid posttranslational changes that occur upon GLV6 perception, followed by a transcriptomics experiment to characterize the downstream responses. Combining the data obtained throughout this project will result in a better understanding of GLV6 signaling as well as peptide signaling in general, and will yield new insights in the regulation of LR development and ACDs.